Pulmonary

Any lesion that results in either increased pulmonary blood flow or pulmonary venous obstruction can cause increased pulmonary interstitial fluid with decreased pulmonary compliance and increased work of breathing.¹⁴ Patients with cyanotic heart disease have increased minute ventilation and maintain normocarbia.¹⁵ These patients have a normal ventilatory response to hypercapnia but a blunted response to hypoxemia that normalizes after corrective surgery and the establishment of normoxia.^16–18 End-tidal CO₂ underestimates arterial Paco₂ in cyanotic patients with decreased, normal, or even increased pulmonary blood flow.¹⁹

Although enlarged hypertensive pulmonary arteries or an enlarged left atrium can impinge on bronchi in children, this is rare in adults. Late-stage Eisenmenger syndrome can result in hemoptysis, and patients with Eisenmenger physiology and erythrocytosis can develop thrombosis of upper lobe pulmonary arteries.²⁰ Prior thoracic surgery could have injured the phrenic nerve with resultant diaphragmatic paresis or paralysis.

Scoliosis can occur in up to 19% of CHD patients, most commonly in cyanotic patients. It can also develop in adolescence, years after surgical resolution of cyanosis.²¹ The relative contributions of cyanosis and congenital cardiovascular defects versus early lateral thoracotomy remain unclear: Scoliosis occurs more commonly with open surgical versus interventional techniques but is nevertheless increased over the general population in children with coarctation or patent ductus who had percutaneous rather than open interventions.²² Scoliosis is rarely severe enough to impact respiratory function.

In an attempt to increase pulmonary blood flow, large collateral vessels originating from the aorta may have developed. These are sometimes embolized in the catheterization laboratory before thoracic surgery to prevent excessive intraoperative blood loss.

Hematologic

Hematologic manifestations of chronic CHD are primarily a consequence of longstanding cyanosis and incorporate abnormalities of both hemostasis and red cell regulation. Longstanding hypoxemia causes increased erythropoietin production in the kidney and resultant increased red cell mass. Because solely red cell production is affected, these patients are correctly referred to as erythrocytotic rather than polycythemic. There is, however, a fairly poor relation among oxygen saturation, red cell mass, and 2,3-diphosphoglycerate.²³ The oxygen-hemoglobin dissociation curve is normal or minimally shifted to the right. Most patients have established an equilibrium state at which they have a stable hematocrit and are iron replete. Some patients, however, develop excessive hematocrits and are iron deficient, causing a hyperviscous state. Iron-deficient red cells are less deformable and have been said to cause increased viscosity for the same hematocrit.²⁴ However, recently there is some conflicting evidence.²⁵ Symptoms of hyperviscosity are uncommon and typically develop only at hematocrits exceeding 65% provided the patient is iron replete. Iron deficiency also shifts the oxygen-hemoglobin dissociation curve to the right, decreasing oxygen affinity in the lungs.²⁶ Symptoms of hyperviscosity are listed in Box 20-3. Iron deficiency can be the result of misguided attempts to reduce the hematocrit by means of repeated phlebotomies.²⁷ The red cells in these patients may be hypochromic and microcytic despite the high hematocrit. Assessment of iron status is best done by measures of serum ferritin and transferrin rather than inferences from red cell indices.²⁷ Treatment with oral iron needs to be undertaken with care because rapid increases in hematocrit can result.

Symptomatic hyperviscosity is the indication for treatment to temporarily relieve symptoms. It is not indicated to treat otherwise asymptomatic increased hematocrits (generally hemoglobin > 20 and hematocrit > 65). Treatment is by means of a partial isovolumic exchange transfusion, and it is assumed that the increased hematocrit is not related to dehydration. Partial isovolumic exchange transfusion usually results in regression of symptoms within 24 hours. It is rare to require exchange of more than 1 unit of blood. Before surgery, phlebotomized blood can be banked for autologous perioperative retransfusion if required. Elective preoperative isovolumic exchange transfusion has decreased the incidence of hemorrhagic complications of surgery.^28,29

Hyperviscosity and erythrocytosis can cause cerebral venous thrombosis in younger children, but it is not a problem in adults, regardless of the hematocrit.²⁰ Protracted preoperative fasts need to be avoided in erythrocytotic patients because they can be accompanied by rapid increases in the hematocrit.

Bleeding dyscrasias have been described in up to 20% of patients. A variety of clotting abnormalities have been described in association with cyanotic CHD, although none uniformly.³⁰ Bleeding dyscrasias are uncommon until the hematocrit exceeds 65%, although excessive surgical bleeding can occur at lower hematocrits. Generally, higher hematocrits are associated with a greater bleeding diathesis. Abnormalities of a variety of factors in both the intrinsic and extrinsic coagulation pathways have been described inconsistently. Both cyanotic and acyanotic patients have been reported with deficiencies of the largest von Willebrand factor multimers, which have normalized after reparative surgery.³¹ Fibrinolytic pathways are normal.³²

The decreased plasma volume in erythrocytic blood can result in spuriously increased measures of the prothrombin and partial thromboplastin times, and the fixed amount of anticoagulant will be excessive because it presumes a normal plasma volume in the blood sample. Erythrocytic blood has more red cells and less plasma in the same volume. If informed in advance of a patient’s hematocrit, the clinical laboratory can provide an appropriate sample tube. Normalizing to a hematocrit of 45%, the amount of citrate added to the tube can be calculated as follows:

Platelet counts are typically normal or occasionally low, but bleeding is not due to thrombocytopenia. Platelets are reported per milliliter of blood, not milliliter of plasma. When corrected for the decreased plasma fraction in erythrocytic blood, the total plasma platelet count is closer to normal. That said, abnormalities in platelet function and life span have on occasion been reported.^33,34 Patients with low-pressure conduits (Fontan pathway) or synthetic vascular anastomoses are often maintained on antiplatelet drugs.

Cyanotic erythrocytotic patients have excessive hemoglobin turnover, and adults have an increased incidence of calcium bilirubinate gallstones. Biliary colic can develop years after cyanosis has been resolved by cardiac surgery.²⁰

A variety of mechanical factors can also affect excessive surgical bleeding in cyanotic CHD patients. These factors include increased tissue capillary density, increased systemic venous pressure, aortopulmonary and transpleural collaterals that have developed to increase pulmonary blood flow, and prior thoracic surgery. Aprotinin and ε-aminocaproic acid improve postoperative hemostasis in patients with cyanotic CHD.³⁵ The results with tranexamic acid have been mixed.³⁶

Renal

Some degree of renal insufficiency is not uncommon in adults with CHD, and the severity is a predictor of mortality. Moderate or severe renal dysfunction (estimated glomerular filtration rate < 60 mL/min/m²) carry a fivefold increased risk for death at 6-year follow-up compared with patients with normal glomerular filtration rate and a threefold increase over those with mild increases in glomerular filtration rate.³⁷ Renal dysfunction is particularly prevalent in cyanotic patients and those with poor cardiac function. Adult patients with cyanotic CHD can develop abnormal renal histology with hypercellular glomeruli and basement membrane thickening, focal interstitial fibrosis, tubular atrophy, and hyalinized afferent and efferent arterioles.³⁸ Cyanotic CHD is often accompanied by increases in plasma uric acid levels that are due to inappropriately low fractional uric acid excretion.³⁹ Decreased urate reabsorption is thought to result from renal hypoperfusion with a high filtration fraction. Despite the increased uric acid levels, urate stones and urate nephropathy are rare.⁴⁰ Although arthralgias are common, true gouty arthritis is less frequent than would be expected from the degree of hyperuricemia.³⁹ There appears to be an increased incidence of postcardiopulmonary bypass renal dysfunction in adults with longstanding cyanosis.⁴¹

Neurologic

Adults with persistent or potential intracardiac shunts remain at risk for paradoxic embolism. Paradoxical emboli can occur even through shunts that are predominantly left to right because during the cardiac cycle there can be small transient reversals of the shunt direction. It has been said that, unlike in children, adults with cyanotic CHD are not at risk for the development of cerebral thrombosis despite the hematocrit.^20,42 However, this assertion has been challenged by Ammash and Warnes,⁴³ who suggested an association of stroke not with red cell mass, but with iron deficiency and repeated venesection. Adults do, however, remain at risk for the development of brain abscess. A healed childhood brain abscess can provide the nidus for the development of seizures throughout life.

Prior thoracic surgery can result in permanent peripheral nerve damage. Surgery at the apices of the lungs is particularly associated with the risk for nerve damage. These operations would include Blalock–Taussig shunts, ligation of patent ductus arteriosus (PDA), banding of the pulmonary artery, and repair of aortic coarctation. Nerves that are susceptible to injury include the recurrent laryngeal nerve, the phrenic nerve, and the sympathetic chain. The incidence of migraine headaches is greater in adults with CHD compared with a control group with acquired heart disease (45% vs. 11%) and is increased in left-to-right, right-to-left, and no-shunt groups.⁴⁴

Vasculature

Vessel abnormalities can be congenital or iatrogenic. They can affect the suitability of vessels for cannulation by the anesthesiologist or measurement of correct pressures. These abnormalities are described in Table 20-3.

TABLE 20-3 Potential Vascular Access Issues

Pregnancy

The physiologic changes of pregnancy, labor, and delivery can significantly alter the physiologic status of women with CHD. Several texts are available that specifically discuss issues of the pregnant woman with CHD in more detail than is possible here,^45–47 and there has been a recent review of generic cardiac surgery in the parturient.⁴⁸ Management and clinical outcomes during pregnancy and delivery for several cardiac lesions are included under the later discussions of those lesions.

Although cardiac complications, spontaneous abortions, premature delivery, thrombotic complications, peripartum endocarditis, and poor fetal outcomes can occur,⁴⁹ successful pregnancy to term with vaginal delivery is possible for most patients with congenital defects.⁵⁰ High-risk factors for mother and fetus are shown in Box 20-4. Eisenmenger physiology is a particular risk factor. Up to 47% of cyanotic women have worsening of functional capacity during pregnancy.⁵¹ Hematocrits greater than 44% are associated with birth weights in less than the 50th percentile, and fetal death is about 90% or more with hemoglobin levels greater than 18 gm/dL or oxygen saturation less than 85%, with most losses in the first trimester. The increases in stroke volume and cardiac output during pregnancy can stress an already pressure-overloaded ventricle. The decrease in systemic vascular resistance that accompanies pregnancy is better tolerated by women with regurgitant lesions and typically offsets the added insult of pregnancy-related hypervolemia. The decrease in systemic vascular resistance can, however, increase right-to-left shunting. Hypervolemia can be problematic in patients with poor ventricular function. Maternal cyanosis is associated with increased incidences of prematurity and intrauterine growth retardation. Profound cyanosis is associated with a high rate of spontaneous abortion.⁵² Endocarditis prophylaxis is not currently recommended for vaginal deliveries.⁵³ The recurrence risk rate of any congenital cardiac defect in a newborn is 2.3% with one affected older sibling (any defect), 7.3% with two, 6.7% if the mother has a congenital cardiac defect, but only 2.1% if the father is affected.² However, it has become apparent that recurrence risk can be specific to the type of maternal defect and the underlying genetic basis. If possible, pregnancies in mothers with CHD should be managed in a high-risk obstetric center with cardiologists experienced with the care of adult CHD, and with early consultation with the obstetric anesthesia service. Women on long-term anticoagulation will likely need peripartum modifications, and postpartum thromboembolism is a potential significant problem.

Anesthesiologists will generally encounter pregnant patients well into the last trimester. Most of the major physiologic changes associated with pregnancy occur before the third trimester, and if the patients have maintained good functional status to this point, they will have declared themselves to be in a relatively low-risk group. Pregnancy is a stress test, and if they have successfully arrived at the mid-to-late third trimester, it is more likely that they will successfully tolerate delivery. Also, many high-risk women will have been counseled to avoid pregnancy. There is no a priori reason to favor an instrumented or Caesarean delivery over a vaginal one. This is an obstetric, not cardiologic decision. A functioning epidural makes uterine contractions easy to tolerate. Bearing down, associated with the second stage, requires close observation. The third stage can be accompanied by an autotransfusion of placental blood, or potentially with hypovolemia with uterine atony and hemorrhage Oxytocin will decrease systemic vascular resistance and increase heart rate and pulmonary vascular resistance. Methylergonovine will increase systemic vascular resistance. These rapid changes in loading conditions can be poorly tolerated in mothers with fixed cardiac output and pulmonary edema, or heart failure can develop.

Some mothers will be taking medications for their cardiac condition, including antiarrhythmics. In general, these are safe for the infant.⁵⁴ Exceptions include β-blockers that can interfere with fetal growth and the response of the fetus to the stress of labor, as well as amiodarone that can affect fetal thyroid function. Maternal cardioversion would appear to be safe for the fetus at all stages, because of the low intensity of the electrical field at the uterus. However, the fetus should be monitored throughout the procedure. Women with implanted internal defibrillators have carried successfully to term.⁵⁵ Should cardiopulmonary bypass (CPB) be required during pregnancy, it carries with it increased fetal risk, particularly if hypothermia is used.

Psychosocial

Teenagers with CHD are certainly no different from other teenagers in that issues of denial, a sense of immortality, and risk-taking behavior can affect optimal care for these youngsters. Bodies that carry scars from prior surgery and physical limitations can complicate the body-conscious teenage years. Although most adolescents and adults with CHD function well, adults with CHD are less likely to be married or cohabitating and are more likely to be living with their parents.⁵⁶ There are several series of adolescent and adult patients and psychosocial outcome, but there are no well-done controlled studies.^57–64 It has been suggested that depression is common and can exacerbate the clinical consequences of the cardiac defect.

Adolescent CHD patients have higher medical care expenses than the general population, and they can have difficulty in obtaining life and health insurance after they can no longer be covered under their parents’ policies.^65–67 Life insurance is somewhat more available to adult CHD patients than in the past; however, policies vary widely among insurers.⁶⁸

Aortic Stenosis

Most aortic stenosis in adults is due to a congenitally bicuspid valve that does not become problematic until late middle age or later, although endocarditis risk is lifelong. Congenital aortic stenosis can, on some occasions, however, become severe enough to warrant surgical correction in adolescence or young adulthood, in addition to those severely affected valves that present in infancy. Once symptoms (angina, syncope, near-syncope, heart failure) develop, survival is markedly shortened. Median survival is 5 years after the development of angina, 3 years after syncope, and 2 years after heart failure.⁷⁴ Anesthetic management of aortic stenosis does not vary whether the stenosis is congenital (most common) or acquired (see Chapter 19).

Most mothers with aortic stenosis can successfully carry pregnancies to term and have vaginal deliveries. Severe stenosis (valve area < 1.0 cm²) can result in clinical deterioration and maternal and fetal mortality. Hemodynamic monitoring during delivery with maintenance of adequate preload and avoidance of hypotension are critical. When surgical intervention is required during pregnancy, percutaneous balloon valvuloplasty appears to carry lower risk than open valvotomy.

Aortopulmonary Shunts

Depending on their age, adult patients may have had one or more of several aortopulmonary shunts to palliate cyanosis during childhood. These are shown in Figure 20-1. Although life saving, there were considerable shortcomings of these shunts in the long term. All were inherently inefficient, as some of the oxygenated blood returning through the pulmonary veins to the left atrium and ventricle would then return to the lungs through the shunt, thus volume loading the ventricle. It was difficult to quantify the size of the earlier shunts such as the Waterston (side-to-side ascending aorta to right pulmonary artery) and Potts (side-to-side descending aorta to left pulmonary artery). If too small, the patient was left excessively cyanotic; if too large, there was pulmonary overcirculation with the risk for development of pulmonary vascular disease. The Waterston, in fact, could, on occasion, stream blood flow unequally, resulting in a hyperperfused, hypertensive ipsilateral (right) pulmonary artery and a hypoperfused contralateral (left) pulmonary artery. There were also surgical issues when complete repair became possible. Takedown of Waterston shunts often required a pulmonary arterioplasty to correct deformity of the pulmonary artery at the site of the anastomosis, and the posteriorly located Potts anastomoses could not be taken down from a median sternotomy. Patients with a classic Blalock–Taussig shunt almost always lack palpable pulses on the side of the shunt. Even if there is a palpable pulse (from collateral flow around the shoulder), blood pressure obtained from that arm will be artifactually low. Even after a modified Blalock–Taussig shunt (using a piece of Gore-Tex tubing instead of an end-to-side anastomosis of the subclavian and pulmonary arteries), there can be a blood pressure disparity between the arms. Preoperative blood pressure should be measured in both arms to ensure a valid measurement (Box 20-5).

Figure 20-1 Various aortopulmonary anastomoses.

The illustrated heart is one with tetralogy of Fallot. The anastomoses are: 1, modified Blalock-Taussig; 2, classic Blalock-Taussig; 3, Waterston (Waterston-Cooley); and 4, Potts.

(From Baum VC: The adult with congenital heart disease. J Cardiothorac Vasc Anesth 10:261, 1996.)

Atrial Septal Defect and Partial Anomalous Pulmonary Venous Return

There are several anatomic types of ASD. The most common type, and if otherwise undefined the presumptive type, is the secundum type located in the midseptum. The primum type at the lower end of the atrial septum is a component of endocardial cushion defects, the most primitive of which is the common atrioventricular canal (see later). The sinus venosus type, high in the septum near the entry of the superior vena cava (SVC), is almost always associated with partial anomalous pulmonary venous return, most frequently drainage of the right upper pulmonary vein to the low SVC. An uncommon atrial septal–type defect is when blood passes from the left atrium to the right via an unroofed coronary sinus. For purposes of this section, only secundum defects are considered, although the natural histories of all of the defects are similar (Box 20-6).

Both the natural history and the postoperative outcome of ASDs and the physiologically related partial anomalous venous return are similar.^75–77 Because the symptoms and clinical findings of an ASD can be quite subtle and patients often remain asymptomatic until adulthood, ASDs represent approximately one third of all CHD discovered in adults. Although asymptomatic survival to adulthood is common, significant shunts (_p/_s > 1.5:1) will probably cause symptoms over time, and paradoxical emboli can occur through defects with smaller shunts. Surgical repair of restrictive lesions 5 mm or smaller in size does not impact the natural history. Thus, surgical closure of small lesions is not indicated in the absence of paradoxical emboli. Effort dyspnea occurs in 30% by the third decade, and atrial flutter or fibrillation in about 10% by age 40.⁷⁵ The avoidance of complications developing in adulthood provides the rationale for surgical repair of asymptomatic children. The mortality for a patient with an uncorrected ASD is 6% per year after 40 years of age, and essentially all patients older than 60 years are symptomatic.^75–77 Large, unrepaired defects can cause death from atrial tachyarrhythmias or right ventricular failure in 30- to 40-year-old patients.⁷⁸ With the decreased left ventricular diastolic compliance accompanying the systemic hypertension or coronary artery disease that is common with aging, left-to-right shunting increases with age. Pulmonary vascular disease typically does not develop until after the age of 40, unlike ventricular or ductal level shunts, which can lead to it in early childhood. Mitral insufficiency can be found in adult patients and is significant in about 15% of adult patients.⁷⁹ Paradoxical emboli remain a lifelong risk.

Late closure of the defect, after 5 years of age, has been associated with incomplete resolution of right ventricular dilation.⁸⁰ Left ventricular dysfunction has been reported in some patients having defect closure in adulthood, and closure, particularly in middle age, may not prevent the development of atrial tachyarrhythmias or stroke.^81–84 Survival of patients without pulmonary vascular disease has been reported to be best if operated on before 24 years of age, intermediate if operated on between 25 and 41 years of age, and worst if operated on thereafter.⁸⁴ However, more recent series have shown that even at ages older than 40, surgical repair provides an overall survival and complication-free benefit compared with medical management.⁸⁵ Surgical morbidity in these patients is primarily atrial fibrillation, atrial flutter, or junctional rhythm.⁸² Current practice is to close these defects in adults in the catheterization laboratory via transvascular devices if anatomically practical (Figure 20-2). For example, there needs to be an adequate rim of septum around the defect to which the device can attach. Device closure is inappropriate if the defect is associated with anomalous pulmonary venous drainage. The indications for closure with a transvascular device are the same as for surgical closure.⁸⁶

Figure 20-2 Closure of an atrial septal defect in an adult with use of a transvascular device (the Amplatzer septal occluder).

A, Radiograph. B, Transesophageal echocardiogram. The device is clearly visualized spanning and occluding the atrial septal defect. LA, left atrium; RA, right atrium.

(Courtesy of Dr. Scott Lim.)

An otherwise uncomplicated secundum ASD, unlike most congenital cardiac defects, is not associated with an increased endocarditis risk.⁸⁷ Presumably, this is because the shunt, although potentially large, is low pressure and unassociated with jet lesions of the endocardium.

Although some discussion is given to onset times with intravenous or inhalation induction agents, clinical differences are hard to notice with modern low-solubility volatile agents. Thermodilution cardiac output reflects pulmonary blood flow, which will be in excess of systemic blood flow. Pulmonary arterial catheters are not routinely indicated. Patients generally do tolerate any appropriate anesthetic; however, particular care should be taken in patients with pulmonary arterial hypertension or right-sided failure.

Most women with an ASD tolerate pregnancy well. However, the normal hypervolemia associated with pregnancy can result in heart failure in women with large defects. Hypovolemia accompanying delivery can result in right-to-left shunting through the defect, and there is a risk for pulmonary thromboembolism or paradoxical embolism.

Coarctation of the Aorta

Unrepaired coarctation of the aorta in the adult brings with it significant morbidity and mortality. Mortality rate is 25% by age 20, 50% by age 30, 75% by age 50, and 90% by age 60.^78,88–90 Left ventricular aneurysm, rupture of cerebral aneurysms, and dissection of a postcoarctation aneurysm all contribute to the excessive mortality. Left ventricular failure can occur in patients older than 40 with unrepaired lesions. If repair is not undertaken early, there is incremental risk for the development of premature coronary atherosclerosis. Even with surgery, coronary artery disease remains the leading cause of death 11 to 25 years after surgery.⁹¹ Coarctation is accompanied by a bicuspid aortic valve in the majority of patients. Although endocarditis of this abnormal valve is a lifelong risk, these valves often do not become stenotic until middle age or later. Coarctation can also be associated with mitral valve abnormalities (Box 20-7).

Aneurysms at the site of coarctation repair can develop years later (Figure 20-3), and restenosis as well can develop in adolescence or adulthood. Repair includes resection of the coarctation and end-to-end anastomosis. Because this sometimes resulted in recoarctation when done in infancy, for many years a common repair was the Waldhausen or subclavian flap operation, in which the left subclavian artery is ligated and the proximal segment opened and rotated as a flap to open the area of the coarctation. Aneurysms in the area of repair are a particular concern in adolescents and adults after coarctectomy. Persistent systemic hypertension is common after coarctation repair.⁹² The risk for hypertension parallels the duration of unrepaired coarctation. Adult patients require continued periodic follow-up for hypertension. A pressure gradient of 20 mm Hg or more (less in the presence of extensive collaterals) is an indication for treatment.⁹³ Recoarctation can be treated surgically or by balloon angioplasty with stenting.⁹⁴ Surgical repair of recoarctation or aneurysm in adults is associated with increased mortality and can be associated with significant intraoperative bleeding because of previous scar or extensive collateral vessels. It requires lung isolation for optimal surgical exposure and placement of an arterial catheter in the right arm. Endovascular repair by ballooning/stenting has proved useful for these patients.^95,96

Figure 20-3 Magnetic resonance image of a 37-year-old man showing descending thoracic aortic pseudoaneurysm at the site of a coarctation that had been repaired years earlier. This patient also has a bicuspid aortic valve and an aneurysm of the ascending aorta that was later repaired.

(Courtesy of Dr. Christopher Kramer.)

Half of patients operated on after age 40 have persistent hypertension, and many of the remainder have an abnormal hypertensive response to surgery. Long-term survival is worse for patients having repair later in life. Patients older than 40 undergoing repair have a 15-year survival rate of only 50%.⁹¹

Blood pressure should be obtained in the right arm unless pressures in the left arm or legs are known to be unaffected by residual or recurrent coarctation. Postoperative hypertension is common after repair of coarctation and often requires treatment for some months. Postoperative ileus is also common, and patients should be maintained NPO for about 2 days.

Pregnancy can exacerbate preexisting hypertension in women with unrepaired lesions, increasing the risk for aortic dissection or rupture, heart failure, angina, and rupture of a circle of Willis aneurysm. Adequate blood pressure control during pregnancy is paramount in these women. Most aortic ruptures during pregnancy occur during labor and delivery. Presumably, epidural analgesia would moderate hypertension during delivery.

Congenitally Corrected Transposition of the Great Vessels (l-Transposition, Ventricular Inversion)

“Transposition” in this context refers solely to the fact that the aorta arises anterior to the pulmonary artery. It bears no reference to the origin of blood in the aorta or pulmonary artery, or to the ventricle of origin of those vessels. In l-transposition, as a consequence of the embryonic heart tube rotating to the left rather than to the right, the flow of blood is through normal vena cavae to the right atrium, through a mitral valve to a right-sided anatomic left ventricle, to the pulmonary artery, through the pulmonary circulation, to the left atrium, through a tricuspid valve to a left-sided anatomic right ventricle, and thence to the aorta (Figure 20-4) Although anatomically altered, the physiologic flow of blood is appropriate and there are no associated shunts. l-Transposition of the great arteries (L-TGA) is frequently associated with other cardiac lesions, most commonly a ventricular septal defect (VSD), subpulmonic stenosis, heart block, or systemic atrioventricular (tricuspid) valve regurgitation. In the absence of any of these associated cardiac defects, L-TGA will usually be asymptomatic through infancy and childhood. When l-transposition is an isolated lesion, most patients maintain normal biventricular function through early adulthood, and can attain a normal life span.

Figure 20-4 Diagram of the anatomy of L-TGA.

Note that the atrioventricular valves are associated with the “usual” ventricle. Ao, aorta; LA, left atrium; LV, anatomic left ventricle; MV, mitral valve; PA, pulmonary artery; RA, right atrium; RV, anatomic right ventricle; TV, tricuspid valve.

Systemic atrioventricular (tricuspid) valve insufficiency may not develop until later in life, resulting in approximately 60% of patients being diagnosed as adults.⁹⁷ Dysfunction of the right or systemic ventricle can develop with aging, and asymptomatic aging is relatively uncommon.⁹⁸ By age 45, heart failure will be present in 67% of those patients with associated lesions and 25% of those without.⁹⁹ These patients can be born with congenital heart block, which can progress in degree. Second- or third-degree heart block occurs at a rate of about 2% per year. More than 75% of patients develop some degree of heart block, although the intrinsic pacemaker remains above the His bundle with a narrow QRS complex. l-Transposition can be associated with an Ebstein-like deformity of the systemic atrioventricular (tricuspid) valve, and there can be a bundle of Kent causing the Wolff-Parkinson-White syndrome associated with that abnormal valve. There is a significant incidence of tricuspid valve insufficiency in the systemic ventricle, and this is greater still in patients with an Ebstein’s deformity of the valve.¹⁰⁰ Anesthetic management depends on the presence of any associated lesions and the adequacy of right (systemic) ventricular function.

Although women generally do well with pregnancy,¹⁰¹ the physiologic stresses of pregnancy and delivery can result in ventricular or valvular dysfunction, particularly with baseline dysfunction and/or an insufficient systemic atrioventricular valve; but even if these develop, pregnancy can be successfully managed.^101–104 The decrease in systemic vascular resistance associated with both pregnancy and neuraxial analgesia might be advantageous to women with tricuspid (systemic) valve insufficiency. The acute autotransfusion associated with delivery could potentially cause problems for women with existing diminished systemic ventricle function.

Ebstein’s Anomaly of the Tricuspid Valve

Ebstein’s anomaly, one of arrested or incomplete delamination of the embryonic tricuspid valve from the right ventricular myocardium, resulting in apically displaced valve tissue, is the most common cause of congenital tricuspid insufficiency. The septal leaflet tends to be the most dysplastic. The anterior leaflet tends to be large and redundant. The defect is associated with a patent foramen ovale or a secundum ASD. There is “atrialization” of part of the right ventricle. The displacement of the tricuspid valve toward the right ventricular apex results in a portion of the right ventricle being above the tricuspid valve and becoming functionally part of the right atrium. Apicalization of the tricuspid valve results in a portion of the heart above the valve having a ventricular intracardiac electrogram (it is ventricular myocardium) but atrial pressures (it lies above the tricuspid valve). The right atrium can be massively enlarged (Figure 20-5), and the right ventricle, lacking the inflow portion that is now part of the right atrium, is smaller than usual with varying degrees of pulmonic stenosis. Patients with l-transposition (see earlier) can have Ebstein’s anomaly of a left-sided tricuspid valve.

Figure 20-5 Ebstein’s anomaly of the tricuspid valve.

This echocardiogram shows the apically displaced redundant tricuspid valve tissue and a massively enlarged right atrium with bowing of the atrial septum to the left. LA, left atrium; LV, left ventricle; MV, mitral valve; RA, right atrium; RV, right ventricle; TV, tricuspid valve.

(From Baum VC: Abnormalities of the atrioventricular valves. In Lake CL, Booker P [eds]: Pediatric cardiac anesthesia, 4th ed. Philadelphia, 2004: Lippincott Williams & Wilkins.)

Symptoms will vary based on the amount of displacement of the valve and the size of the smaller than normal right ventricle. Cyanosis from atrial-level right-to-left shunting can be a neonatal phenomenon, resolving with the normal postnatal decrease in pulmonary vascular resistance, only to recur in adolescence or adulthood. Very mild disease is quite compatible with asymptomatic survival into adulthood, although overall earlier reports suggested a mean age at death of about 20 years, with about one third dying before 10 years of age and only 15% survival rate by 60 years.^105–107 About half of patients experience development of arrhythmias, typically supraventricular tachyarrhythmias. Once symptoms develop, disability rapidly progresses.

Valve repair is currently the approach of choice, and only uncommonly will tricuspid valve replacement be required.¹⁰⁸ Additional intervention may be required for progressive insufficiency, stenosis, prosthetic valve failure, or valve replacement with growth. After valve replacement, up to 25% of patients experience development of high-grade atrioventricular block. Ebstein’s valves are often associated with a right-sided bypass tract, causing Wolff-Parkinson-White syndrome. This is of concern because 25% to 30% of patients experience development of supraventricular tachyarrhythmias. The dilated right atrium is ready substrate for the development of atrial fibrillation. In addition to a decrease in cardiac performance, atrial fibrillation is also potentially dangerous in patients with underlying Wolff-Parkinson-White syndrome because very high atrial rates can be conducted to the ventricle through the bypass tract.

The major concerns when anesthetizing patients who have Ebstein’s anomaly include decreased cardiac output, right-to-left atrial-level shunting with cyanosis, and the propensity for atrial tachyarrhythmias. The right atria of these patients are very sensitive, and arrhythmias are easily induced by catheters or guidewires passed into the right atrium or during surgical manipulation; arrhythmias remain a concern into the postoperative period. Supraventricular arrhythmias should be treated aggressively. If associated with significant hypotension, the arrhythmia needs to be electrically cardioverted.

In the absence of marked cyanosis, pregnancy and delivery are generally well tolerated. There is, however, an increased incidence of prematurity and fetal loss, and birth weights are lower in infants of cyanotic mothers,¹⁰⁹ as well as an increased incidence of CHD in the offspring.

Eisenmenger Syndrome

Eisenmenger described a particular type of large VSD with dextroposition of the aorta.¹¹⁰ In a general way, the term Eisenmenger syndrome has come to describe the clinical setting in which a large left-to-right cardiac shunt results in the development of pulmonary vascular disease and has been the subject of recent reviews.¹¹¹ Although early on the pulmonary vasculature remains reactive, with continued insult, pulmonary hypertension becomes fixed and does not respond to pulmonary vasodilators. Ultimately, the level of pulmonary vascular resistance is so high that the shunt reverses and becomes right to left. Clinically, patients who are cyanotic from intracardiac right-to-left shunting are deemed to have Eisenmenger physiology even though their PVR may not yet truly be “fixed.” This is the intermediate phase of the disease before progression to a truly fixed PVR. That is, at baseline they shunt right to left but may still retain some pulmonary vascular reactivity in the presence of vasodilating agents such as oxygen or nitric oxide. The degree of reactivity can be determined in the catheterization laboratory by measuring the pulmonary blood flow on room air, pure oxygen, and pure oxygen with nitric oxide added. The development of pulmonary vascular disease is dependent on shear rate. Lesions with high shear rates, such as a large VSD or a large PDA, can result in pulmonary hypertension in early childhood. Lesions such as an ASD with high pulmonary blood flow but low pressure may not result in pulmonary vascular disease until late middle age. Pulmonary vascular disease progression is also accelerated in patients living at high altitudes.

The most common presenting symptom is dyspnea on exertion. Additional symptoms include palpitations, edema, hemoptysis, syncope, hyperpnea, and of course, increasing cyanosis. Hepatic synthetic function can be altered from the increased central venous pressure. There can be CNS symptoms from increased blood viscosity from the erythrocytosis associated with cyanosis. Right ventricular ischemia is a possibility. Patients may be on chronic therapy with drugs such as intravenous prostacyclin, an oral phosphodiesterase-5 inhibitor such as sildenafil (e.g., Revatio), or an oral endothelin receptor antagonist such as bosentan (e.g., Tracleer). Because of the risk for pulmonary thromboses,¹¹² patients may be on chronic anticoagulants.

Eisenmenger physiology is compatible with survival into adulthood.^113,114 However, reported rates of survival after diagnosis vary, probably based on the relatively long life expectancy and variability in the time of diagnosis. Cantor et al¹¹⁵ reported median survival to 53 years but with wide variation. Saha et al¹¹⁶ reported a survival rate of 80% at 10 years after diagnosis and 42% at 25 years. Oya et al,¹¹⁷ however, reported survival rate of 77% at 5 years and 58% at 10 years. Syncope, increased central venous pressure, and arterial desaturation to less than 85% are all associated with poor short-term outcome.¹¹³ Other factors associated with mortality include syncope, age at presentation, functional status, supraventricular arrhythmias, increased right atrial pressure, renal insufficiency, severe right ventricular dysfunction, and trisomy 21. Most deaths are sudden cardiac deaths. Other causes of death include heart failure, hemoptysis, brain abscess, thromboembolism, and complications of pregnancy and noncardiac surgery.¹¹⁸ These patients face potentially significant perioperative risks. Findings of Eisenmenger syndrome are summarized in Table 20-5.

TABLE 20-5 Findings in Eisenmenger Syndrome

Surgical closure of cardiac defects with fixed pulmonary vascular hypertension is associated with very high mortality. Lung or heart-lung transplantation is a surgical alternative.¹¹⁹ Although there are several surgical series reporting survival after heart-lung or single- or double-lung transplantation performed for primary pulmonary hypertension, it is unclear whether this cohort of patients is similar to patients with Eisenmenger physiology.

When noncardiac surgery is deemed essential and time permits, a preoperative cardiac catheterization may be helpful to determine the presence of pulmonary reactivity to oxygen or nitric oxide. Fixed pulmonary vascular resistance precludes rapid adaptation to perioperative hemodynamic changes. Changes in systemic vascular resistance are mirrored by changes in intracardiac shunting. A decrease in systemic vascular resistance is accompanied by increased right-to-left shunting and a decrease in systemic oxygen saturation. Systemic vasodilators, including regional anesthesia, need to be used with caution, and close assessment of intravascular volume is important. Epidural analgesia has been used successfully in patients with Eisenmenger physiology, but the local anesthetic needs to be delivered slowly and incrementally with close observation of blood pressure and oxygen saturation.¹²⁰ Postoperative postural hypotension can also increase the degree of right-to-left shunting, and these patients should change position slowly. All intravenous catheters need to be maintained free of air bubbles.

Placement of pulmonary artery catheters in these patients is problematic for a variety of reasons, and they are of less utility than might be expected. Pulmonary arterial hypertension is a risk factor for pulmonary artery rupture from a pulmonary artery catheter. Rupture is particularly worrisome in these cyanotic patients who can also have hemostatic deficits associated with erythrocytosis.¹²¹ Abnormal intracardiac anatomy and right-to-left shunting can make successful passage into the pulmonary artery difficult without fluoroscopy. Relative resistances of the pulmonary and systemic beds are reflected in the systemic oxygen saturation, readily measured by pulse oximetry, so measures of pulmonary artery pressure are not required. In addition, in the presence of right-to-left shunting, thermodilution cardiac outputs do not accurately reflect systemic output. Thus, the value of pulmonary artery catheters in these patients is minimal at best, and they essentially are never indicated. The one potential exception is the patient with an ASD who is at risk for development of right ventricular failure if suprasystemic right ventricular pressure develops.¹²²

Fixed pulmonary vascular resistance is, by definition, unresponsive to pharmacologic or physiologic manipulation, but as previously mentioned, only patients at the true end stage of disease have fixed PVR. Thus, the clinician must still avoid factors known to increase pulmonary vascular resistance, including cold, hypercarbia, acidosis, hypoxia, and α-adrenergic agonists. Although the last of these is commonly listed to be avoided, it seems that in the face of pulmonary vascular disease caused by intracardiac shunting, the systemic vasoconstrictive effects predominate and systemic oxygen saturation increases.

Nerve blocks offer an attractive alternative to general anesthesia if otherwise appropriate. If patients have general anesthesia, consideration should be given to postoperative observation in an intensive or intermediate care unit. Because of the increased perioperative risk, patients should be observed overnight, particularly if they have not had recent surgery or anesthesia, because their responses will be unknown. Ambulatory surgery is possible for patients having uncomplicated minor surgery with sedation or nerve block.

Pregnancy carries a very high mortality risk and risk for premature delivery. From 20% to 30% of pregnancies result in spontaneous abortions, and premature delivery occurs in about half.¹²³ At least half of newborns have intrauterine growth retardation. From 30% to 45% of all pregnancies end in maternal death intrapartum or during the first postpartum week, and successful first pregnancy does not preclude maternal death during a subsequent pregnancy.¹²⁴ The hemodynamic changes of both pregnancy and delivery increase maternal risk. Pulmonary microembolism and macroembolism have caused peripartum maternal deaths, even days after delivery. Factors that influence mortality include thromboembolism (44%), hypovolemia (26%), and preeclampsia (18%).^123,124 Mortality is similar with Cesarean section or vaginal delivery, and both are significantly greater than the mortality rate for spontaneous abortions. Pregnancy should be discouraged in these women. Women who do become pregnant should be closely monitored with arterial catheters during delivery. Epidural analgesia, delivered slowly and incrementally, can moderate many of the deleterious hemodynamic changes of active labor. Pulmonary arterial catheters are of little to no use during delivery. Prompt treatment of blood loss and hypotension during delivery is absolutely required. Postpartum observation should be in an intensive care setting. Pulmonary hypertension in pregnancy was reviewed in detail.^125,126

Endocardial Cushion Defects (Atrioventricular Canal Defects)

The endocardial cushions are embryonic cardiac tissue that form the crux of the heart—the primum (lower) atrial septum, the posterior basal part of the ventricular septum, the septal leaflet of the tricuspid valve, and the anterior leaflet of the mitral valve. The endocardial cushion defects then consist of one or more of a primum ASD, inlet VSD, cleft septal leaflet of the tricuspid valve, and/or cleft anterior leaflet of the mitral valve. The most primitive form is the complete atrioventricular canal. In this defect, there is a single large atrioventricular valve with mitral and tricuspid components with large ASDs and VSDs. This valve is usually “balanced.” In the more complex, unbalanced defects, one component of the valve can be predominant, and this large valve is not centered over the ventricular septum, leading to underfilling of one of the ventricles. These defects can occur alone or can be part of more complex cardiac defects such as tetralogy of Fallot or single ventricle. Half of all children with Down syndrome have CHD; half of these children have an endocardial cushion defect. These lesions are marked by a typical electrocardiogram with first-degree block and a superior QRS axis with a counterclockwise QRS loop. Although adults with unrepaired complete atrioventricular canal will likely have developed inoperable pulmonary arterial hypertension, partial canal defects can sometimes be first diagnosed in adults and will be appropriate candidates for surgical repair. The atrioventricular node and bundle of His are displaced inferiorly, putting them at risk for surgical injury and the induction of heart block.

There is much subtlety required to construct two separate functional atrioventricular valves without residual stenosis or insufficiency of either component. Postoperative or residual mitral insufficiency is not uncommon, and 10% to 30% require repeat surgery.¹²⁷ The strongest predictor of postoperative mitral insufficiency is the degree of preoperative regurgitation of the common atrioventricular valve. Anesthesia for these patients depends on the degree of shunt, valve insufficiency, and pulmonary vascular disease.

Fontan Physiology

In 1968, performing the operation that now bears his name, Fontan and Baudet¹²⁸ proved that it was possible to deliver the entire systemic venous return to the lungs without the benefit of a ventricular pump. The Fontan operation was a landmark development in CHD because it established a “normal” series circulation in patients with a single ventricle. The price to be paid for a series circulation is the unique physiologic demand of passive pulmonary blood flow. Complications never envisioned at the time of the original operation have occurred, necessitating significant changes in operative technique. Fontan’s original operation (Figure 20-6) was soon modified to an atriopulmonary connection¹²⁹ (Figure 20-7). The original strict eligibility criteria¹³⁰ have been liberalized, but patients meeting as many of the criteria as possible still have the best prognosis for good long-term survival. By the mid-1980s, it became clear that the success of Fontan circulation was based on an unobstructed pathway from systemic veins to pulmonary artery, a pulmonary vasculature that was free from anatomic distortion (from previous Blalock-Taussig shunt, for example), low PVR, and good ventricular function without significant atrioventricular valve regurgitation. The incorporation of the atrium in the Fontan pathway proved disappointing. The atrium lost its contractile function, providing no assistance to pulmonary blood flow and causing serious complications. Understanding these complications and how the Fontan operation has evolved is the key to managing these challenging patients whose complex CHD has been palliated, not cured.

Figure 20-6 The original Fontan operation.

Note the classic Glenn shunt connecting the superior vena cava to the right pulmonary artery and the homografts at the inferior vena cava-right atrial junction and connecting the right atrium to the left pulmonary artery.

(From Fontan F, Baudet E: Surgical repair of tricuspid atresia. Thorax 26:240, 1971.)

Figure 20-7 The atriopulmonary modification of the Fontan operation.

(From Kreutzer G, Galindez E, Bono H, et al: An operation for the correction of tricuspid atresia. J Thorac Cardiovasc Surg 66:613, 1973.)

The Modern Fontan Operation

The atriopulmonary connection proved an inefficient method of pulmonary blood flow. Colliding streams of blood from the SVC and inferior vena cava (IVC) resulted in energy loss and turbulence within the atrium.¹⁵⁰ The energy required to propel blood forward into the pulmonary vasculature was lost as blood swirled sluggishly in the dilated atrium (Figure 20-8). The modern Fontan operation is a total cavopulmonary connection (Figure 20-9). The “lateral tunnel Fontan” improved pulmonary blood flow, and only the lateral wall of the atrium was exposed to central venous hypertension. There was no dilated atrium to serve as a source of thrombus. The extensive atrial suture lines, however, remained a risk for arrhythmia. The “extracardiac Fontan” is a further modification of the total cavopulmonary connection. The “extracardiac Fontan” greatly reduces the number of atrial incisions and hopefully the long-term development of atrial arrhythmias. Has the modern Fontan improved outcomes? Reductions in arrhythmia and improvements in overall survival have been noted.¹⁵¹ Results for the extracardiac Fontan are even better than the lateral tunnel Fontan but are limited by the shorter duration of follow-up. It is not yet certain whether the development of long-term complications has been truly reduced or only delayed.

Figure 20-8 Injection of contrast into the inferior vena cava reveals a markedly dilated right atrium after an atriopulmonary Fontan operation.

Figure 20-9 Two variations of the modern Fontan operation, the lateral tunnel and extracardiac operations. IVC, inferior vena cava; RA, right atrium; RPA, right pulmonary artery; SVC, superior vena cava.

(From D’Udekem Y, Iyengar AJ, Cochrane AD, et al: The Fontan procedure: Contemporary techniques have improved long-term outcomes. Circulation 116:I157, 2007.)

Patent Ductus Arteriosus

Beyond the neonatal period, spontaneous closure of a PDA is uncommon. The risk for a longstanding moderate-to-large PDA is volume overloading of the left atrium and left ventricle with the risk for development of pulmonary vascular disease. The progression of pulmonary vascular disease is relatively accelerated when compared with patients with other types of right-to-left shunts. The development of pulmonary vascular disease is dependent on the volume and pressure of the right-to-left shunt. A PDA delivers blood at high shear stress (i.e., arterial pressure) to the pulmonary vasculature, and flow occurs continuously throughout the cardiac cycle. With time, the ductus can become calcified or aneurysmally dilated with a risk for rupture. Ductal calcification or aneurysm increases the risk for surgery, which rarely requires CPB.¹⁶¹ Unrepaired, the natural history is for one third of patients to die of heart failure, pulmonary hypertension, or endocarditis by 40 years of age and two thirds by age 60.¹⁶² Although small PDAs are of no hemodynamic consequence, even small PDAs carry relatively high endocarditis risk. Surgical closure should be considered for all adults with PDA, and transvascular closure by means of one of several devices is possible.¹⁶¹ With calcification and friability of the ductus, if device closure is not practicable, it is possible to do a patch closure from inside the aorta or pulmonary artery.

Small PDAs do not carry a hemodynamic risk for pregnancy. The decrease in systemic vascular resistance accompanying pregnancy could lead to right-to-left shunting in a woman with a large PDA.

Pulmonary Valve Stenosis

Long-term asymptomatic survival is typical of patients, with the exception of neonates with critical stenosis.¹⁶³ There is a 94% survival rate 20 years after diagnosis, and adults generally do not require surgical intervention.¹⁶⁴ With aging, however, right ventricular fibrosis and failure can develop, and this is the most common cause of death, usually in the fourth decade of life. Almost all patients who have relief of stenosis either surgically or by balloon valvuloplasty have normal right ventricular function after surgery. However, abnormal ventricular function may not resolve after late surgical correction. The development of isolated pulmonary valvular stenosis, even of a severe degree, is usually well tolerated during pregnancy, even in the face of the volume overload that accompanies it.¹⁶⁵

In patients with significant right ventricular hypertension, right ventricular ischemia can occur if systemic hypotension and decreased coronary perfusion occur. This is manifest on the electrocardiogram. Coronary ischemia resolves if coronary perfusion pressure is increased, as with use of phenylephrine.

Single Ventricle

See the Fontan Physiology section earlier in this chapter for a detailed discussion.

Tetralogy of Fallot

As with many things in medicine, tetralogy of Fallot was first described by someone else—probably in 1673 by Stenson. The classic description of tetralogy of Fallot includes: (1) a large, nonrestrictive malaligned VSD, with (2) an overriding aorta, (3) infundibular pulmonic stenosis, and (4) consequent right ventricular hypertrophy, all derived from an embryonic anterocephalad deviation of the outlet septum. However, there is a spectrum of disease with more severe defects including stenosis of the pulmonary valve, stenosis of the pulmonary valve annulus, or stenosis and hypoplasia of the pulmonary arteries in the most severe cases. Pentalogy of Fallot refers to the addition of an ASD. With advances in genetics, up to one third or more of cases of tetralogy have been ascribed to one of several genetic abnormalities, including trisomy 21, the 22q11 microdeletion, the genes NKX 2.5 and FOG 2.4, and others. Tetralogy of Fallot is the most common cyanotic lesion encountered in the adult population. Unrepaired or nonpalliated, approximately 25% of patients survive to adolescence, after which the mortality rate is 6.6% per year. Only 3% survive to age 40.¹⁶⁶ Unlike children, teenagers and adults with tetralogy do not develop “tet spells.” Long-term survival with a good quality of life is expected after repair. The 32- to 36-year survival rate has been reported to be 85% to 86%, although symptoms, primarily arrhythmias and decreased exercise tolerance, occur in 10% to 15% at 20 years after the primary repair^167–170 (Box 20-10). In the past, most children with tetralogy were managed with a preliminary palliation with an aortopulmonary shunt such as a Blalock-Taussig, followed by complete correction. Essentially all patients would eventually have come for complete repair. Currently, most children are managed with a complete repair in infancy, without preceding palliation.

It is uncommon to encounter an adolescent or adult with unrepaired tetralogy. However, it can be encountered in immigrants or in patients whose anatomic variation was considered to be inoperable when they were children. In tetralogy, the right ventricle “sees” the obstruction from the pulmonic stenosis. Pulmonary vascular resistance is typically normal to low. Right-to-left shunting is caused by obstruction at the level of the right ventricular outflow tract and is unaffected by attempts at modulating pulmonary vascular resistance. Shunting is minimized, however, by pharmacologically increasing systemic vascular resistance. Increases in the inotropic state of the heart increase the dynamic obstruction at the right ventricular infundibulum and worsen right-to-left shunting. β-Blockers are often used to decrease inotropy. Although halothane was the historic anesthetic of choice in children with tetralogy because of its myocardial depressant effects and ability to maintain systemic vascular resistance, current practice is to use sevoflurane, without undue consequence from a reduction in systemic vascular resistance.¹⁷¹ Anesthetic induction in adults can easily be achieved with any of the available agents, keeping in mind the principles of maintenance of systemic blood pressure, avoidance of hypovolemia, and preventing increases in inotropy.

Patients require closure of the VSD and resolution of the pulmonic stenosis. Although current practice is to repair the VSD through the right atrium in an effort to maintain competence of the pulmonary valve and limit any ventriculotomy, older patients will likely have had repair via a right ventriculotomy. A large right ventriculotomy increases the risks for arrhythmias and sudden death.¹⁷² Patients who have had a right ventriculotomy will have an obligate right bundle branch block pattern on the electrocardiogram. However, unlike the more usual bundle branch block in adults, this represents disruption of the His-Purkinje system only in the right ventricular outflow, in the area of the right ventricular incision. Because most His-Purkinje conduction is intact, it does not carry increased risk for the development of complete heart block. These patients can have an abnormal response to exercise.

Some patients require repair of pulmonic stenosis by placement of a transannular patch, with obligate residual pulmonary insufficiency. Isolated mild-to-moderate pulmonary insufficiency is generally well tolerated, but in the long term, it can contribute to right ventricular dysfunction with a risk for ventricular tachycardia and sudden death. Patients requiring pulmonary valve replacement in their late teens or early 20s after a transannular patch in early childhood are a growing proportion of the adult CHD population. Atrial tachyarrhythmias occur in about one third of adults late after repair and can contribute to late morbidity.^173,174 The development of atrial flutter or atrial reentrant tachycardia is often a harbinger of hemodynamic compromise. The substrate is usually an atrial surgical scar and the trigger is atrial dilation, such as from tricuspid insufficiency with right ventricular dysfunction. The mechanism for the development of ventricular arrhythmias is presumably the same, namely, dilation superimposed on surgical scar.

In some cases, the right ventricular outflow tract patch needs to be extended onto the branch pulmonary arteries to relieve obstruction. Patients with abnormal coronary arteries may have required repair using a right ventricle-to-pulmonary artery conduit to avoid doing a right ventriculotomy in the area of the coronary artery. Repair at a younger age (< 12 years) results in better postoperative right ventricular function.¹⁷⁵ Because there is an unrestrictive VSD, in the unrepaired adult, systemic hypertension developing in adult life imposes an additional load on both ventricles, not just the left. The increase in systemic vascular resistance decreases right-to-left shunting and diminishes cyanosis but at the expense of right ventricular or biventricular failure.

Sudden death or ventricular tachycardia requiring treatment can occur in up to 5.5% of postoperative patients older than 30 years, often years after surgery.^168,169,176 The foci for these arrhythmias are typically in the right ventricular outflow tract in the area that has had surgery, and they can be ablated in the catheterization laboratory. Older age at repair, severe left ventricular dysfunction, postoperative right ventricular hypertension from residual or recurrent outflow tract obstruction, wide-open pulmonary insufficiency, and prolongation of the QRS (to > 180 milliseconds) are all predictors of sudden death.^172,177 Premature ventricular contractions and even nonsustained ventricular tachycardia are not rare but do not seem to be associated with sudden death, making appropriate treatment options difficult.¹⁷⁸ QRS prolongation to longer than 180 milliseconds, although highly sensitive, has a low positive predictive value.¹⁷⁹ The impact of this risk factor in the current group of younger patients who have not had ventriculotomies is unclear because their initial postoperative QRS durations are shorter than in patients who had a right ventriculotomy.

Although for many years it was thought that moderate-to-severe pulmonary insufficiency in these patients was well tolerated, it has become apparent from a number of series that right ventricular dysfunction and both atrial and ventricular arrhythmias can be common long-term sequelae. For this reason, patients with symptomatic pulmonary insufficiency from a transannular patch or aneurysm formation at the site of a right ventricular outflow tract patch can require reoperation to replace a widely incompetent pulmonary valve with a bioprosthetic valve with or without a tricuspid annuloplasty.¹⁸⁰ Interestingly, the incidence of atrial arrhythmias may not be diminished when adult patients have a pulmonary valve placed, although the incidence of ventricular arrhythmias is decreased. Right ventricular dysfunction improves in a variable number of adults, suggesting that pulmonary valve placement be done sooner rather than later. The development of a pulmonary valve that can be delivered via a vascular catheter holds much promise.¹⁸¹

Additional possible late-term complications include residual VSD, patch dehiscence, progressive aortic insufficiency, left ventricular dysfunction from surgical injury to an anomalous coronary artery or longstanding preoperative cyanosis, and heart block from VSD closure (uncommon today). Because patients who have had repairs using a conduit require multiple sternotomies and the valved conduit tends to lie immediately behind and in close proximity to the sternum, sternotomy carries with it significant potential risk for laceration of the conduit. On occasion, the femoral vessels are cannulated for bypass before sternotomy.

Most adult patients require reoperation to repair the right ventricular outflow tract or to insert or replace a valve in the pulmonic position. Other reasons for reoperation include repair of an outflow tract aneurysm at the site of a patch, repair of a residual VSD, or repair of an incompetent tricuspid valve.¹⁷⁰ These patients often have diminished right ventricular diastolic compliance and require higher than normal central venous pressure. Postoperative management includes minimizing pulmonary vascular resistance and maintaining central venous pressure. Patients often require treatment postbypass with an inotrope and afterload reduction.¹⁸²

Women with good surgical results without residual defects should tolerate pregnancy and delivery well with outcomes approximating those of the general population.¹⁸³ Women with uncorrected tetralogy, particularly those with significant cyanosis, have a high incidence of fetal loss (80% with hematocrit > 65%). The decline in systemic vascular resistance that accompanies pregnancy and delivery can worsen cyanosis, and the physiologic volume loading of pregnancy can exaggerate failure of both ventricles.

Transposition of the Great Arteries (d-Transposition)

In d-transposition of the great arteries, there is a discordant connection of the ventricles and the great arteries. The aorta (with the coronary arteries) arises from the right ventricle, and the pulmonary artery arises from the left ventricle. Thus, the two circulations are separate. Postnatal survival requires interchange of blood between the two circulations, typically via a patent foramen ovale and/or a PDA or VSD. With a 1-year mortality rate approximating 100%, all adults with d-transposition have had some type of surgical intervention. Older adults will have had atrial-type repairs (Mustard or Senning), whereas children born after the mid-1980s will have had repair by arterial switch (the Jatene operation). Some will also have had repair of d-transposition with a moderate-to-large VSD by means of a Rastelli operation (see later).

Atrial repairs function by redirecting systemic venous blood to the left ventricle (and thence to the transposed pulmonary artery) and pulmonary venous blood to the right ventricle (and thence to the aorta). The Mustard operation uses an intra-atrial conduit of native pericardium (Figure 20-10), whereas the Senning operation uses native atrial tissue to fashion the conduit. The arterial switch operation transposes transected aorta and pulmonary artery such that they now arise above the appropriate ventricle. This operation also requires transposing the coronary arteries from the aorta to the pulmonary root, which, after the procedure, becomes the aortic root. The Rastelli procedure closes the VSD on a bias such that the left ventricle empties into the aorta and connects the right ventricle to the pulmonary artery by means of a valved conduit.

Figure 20-10 The Mustard operation.

An intra-atrial baffle has directed vena caval blood across the excised atrial septum to the mitral valve and pulmonary venous blood to the tricuspid valve. The right ventricle remains as the systemic ventricle and the left ventricle as the subpulmonary ventricle.

(From Mullins C, Mayer D: Congenital heart disease. A diagrammatic atlas. New York: Wiley-Liss, 1988, by permission of Wiley-Liss, Inc., a subsidiary of John Wiley & Sons, Inc.)

Atrial repairs result in a systemic right ventricle, and these patients consistently have abnormal right ventricular function that can be progressive with a right ventricular ejection fraction of about 40%.¹⁸⁴ Mild tricuspid insufficiency is common, but severe tricuspid insufficiency suggests the development of severe right ventricular dysfunction. There is an 85% to 90% 10-year survival with these operations, but by 20 years, survival is less than 80%.^185–187 Over 25 years, about half experience development of moderate right ventricular dysfunction and one third experience development of severe tricuspid insufficiency.^{185,186,188–190} Although it always remains abnormal, it has been suggested that earlier surgery minimizes right ventricular dysfunction.¹⁹¹ Because of the incidence of right ventricular dysfunction, some patients with atrial repairs have been converted to an arterial switch, after preparation of the left ventricle by a pulmonary artery band to prepare it to tolerate systemic arterial pressure.¹⁹²

Atrial repairs bring an incidence of late electrophysiologic sequelae including sinus node dysfunction (bradycardia), junctional escape rhythms, atrioventricular block, and supraventricular arrhythmias. Atrial flutter occurs in 20% of patients by age 20, with half having progressive sinus node dysfunction by that time.^185,189 On occasion, these tachyarrhythmias can result in sudden death, presumably from 1:1 conduction producing ventricular fibrillation.^185,193 The loss of sinus rhythm in the face of right ventricular (the systemic ventricle) dysfunction can also contribute to late sudden death. The risk for late death after an atrial repair is almost three times greater if there is an associated VSD. The incidence of tachyarrhythmias does decrease, however, after the tenth postoperative year.

An arterial switch operation can be done after a failed atrial repair in adults, but the outcome is generally poor. It is suggested that younger patients do better.¹⁹⁴ Survival after an arterial switch operation, even early in the experience with this operation, is approximately 90% at 10 years.¹⁹⁵ Very-long-term outcome after the arterial switch procedure is still not known. It does appear that there is essentially no mortality after 5 years after surgery, and late surgical reintervention is mostly because of supravalvular pulmonic stenosis.¹⁹⁶ Although many of these children have abnormal resting myocardial perfusion, up to 9% can have evidence of exercise-induced myocardial ischemia.¹⁹⁷ The implication for the development of premature coronary artery disease in adulthood is not known, and there is also some concern about the ultimate function of the neoaortic valve. Patients who have had a Rastelli repair will require episodic reoperation for replacement of the prosthetic conduit valve.

After an atrial or a Rastelli repair, pregnancy and delivery are generally well tolerated, although right ventricular failure and deterioration in functional capacity can occur. There is an increased incidence of prematurity and small-for-date infants in these women.

Truncus Arteriosus

Truncus arteriosus derives from lack of septation of the embryonic truncus arteriosus into aortic and pulmonary artery components, resulting in a single great vessel, the aorta, arising from the heart with a truncal (semilunar) valve. The truncal valve is an amalgamation of the aortic and pulmonary valves, and therefore contains between three and six cusps. In addition, truncal valve insufficiency is a common finding with this morphologically abnormal valve. A large malalignment-type VSD allows filling from both ventricles. The pulmonary arteries arise from the ascending aorta. Although various types have been described depending on the exact anatomy of the pulmonary artery origin, there is really a spectrum of types I through III. Type IV, or pseudotruncus, describes the situation of pulmonary atresia with VSD and supply of the pulmonary arteries from large collaterals originating from the descending aorta. Repair is by closure of the VSD and connection of the right ventricle to the pulmonary artery (or pulmonary arteries) by a conduit containing a homograft valve.

Because of the very high risk for congestive heart failure followed by pulmonary vascular disease in childhood from high pulmonary blood flow from the aorta, essentially all patients who survive to adolescence have had surgical repair or will have inoperable pulmonary vascular disease. The rare exception is the patient with stenosis near the origin of the pulmonary arteries from the aorta. Patients with valved conduits placed in infancy and early childhood have requisite reoperations to replace the conduit with patient growth, even in the face of adequate valve function. Conduits placed in later childhood can suffice until adulthood. There can be ongoing problems with incompetence and stenosis of the truncal valve (postoperatively functioning as the aortic valve), and eventual dysfunction from stenosis and/or incompetence of the homograft conduit is routinely encountered, requiring replacement.^198,199 Because these patients require multiple sternotomies and the valved conduit tends to lie immediately behind and in close proximity to the sternum, sternotomy carries with it significant potential risk for laceration of the conduit. On occasion, the femoral vessels are cannulated for bypass before sternotomy.

Ventricular Septal Defects

The natural history of VSDs has been reviewed in detail.¹⁶³ More than 75% of small and moderate VSDs close spontaneously during childhood by a gradual ingrowth of surrounding septum. Of those that close spontaneously, almost all have closed by 10 years of age. Other mechanisms for natural closure include closure by tricuspid valve tissue, closure by prolapsed aortic leaflet, and closure by endocarditis. Some VSDs result in the development of aortic insufficiency in adults from prolapse of the aortic valve into the defect.²⁰⁰ Although the risk for endocarditis is ongoing, there is no hemodynamic risk for a small VSD in the adult. If pulmonary vascular disease is present, it can progress if closure of a large VSD is delayed.

Although some studies have reported possible ventricular dysfunction years after surgical repair, these are older reports and patients were operated on later than by current standards.^201–203 It does appear, though, that the ventricle successfully remodels from chronic volume overload if surgical correction is done by 5 years of age and perhaps up to 10 to 12 years of age. Iatrogenic heart block is a possible surgical complication, but was much more common in the earlier days of cardiac surgery. Percutaneous closure devices for use with certain VSDs are available, but not currently for widespread commercial use.

Although some discussion is given to onset times with intravenous or inhalation induction agents, clinical differences are hard to notice with modern low-solubility volatile agents. Thermodilution cardiac output reflects pulmonary blood flow, which will be in excess of systemic blood flow. Pulmonary arterial catheters are not routinely indicated. In the patient with a moderate or large left-to-right shunt, low inspired oxygen and moderate hypercarbia avoid intraoperative decreases in pulmonary vascular resistance with pulmonary overcirculation and left ventricular dilation. However, unlike children, it would be rare to encounter adults with large left-to-right shunts. Adults with unrepaired lesions would have either small shunts or would have had large shunts that caused Eisenmenger physiology.

Pregnancy is well tolerated in the absence of preexisting heart failure or pulmonary hypertension. Pregnancy with a naturally or surgically closed defect carries with it no additional risk, in the absence of additional cardiac problems.