Multisystem Disease

Congenital heart disease does not involve only the cardiovascular system; it also causes multisystem disease. It is common for patients to undergo repeated thoracic surgeries, and they are at risk for developing scoliosis, which can lead to pulmonary restriction. Renal impairment is common because of the effects of previous cardiac surgery, nephrotoxic drugs (particularly radiographic contrast agents used during cardiac catheter studies), and associated congenital kidney abnormalities, such as renal dysplasia and hydronephrosis. High systemic venous pressure, such as that which occurs after Fontan-type operations and with right ventricular dysfunction, can lead to pleural effusions, ascites, hepatic congestion, and even cirrhosis. Hepatic dysfunction can also occur due to hepatitis C infection acquired from exposure to infected blood products.

Children who have undergone repair or palliation for congenital heart disease have, on average, lower IQs than their peers and are more likely to have developmental disabilities.^3,4 Many adults with congenital heart disease were cyanotic for long periods of time during their childhoods; they may have experienced periods of circulatory compromise and may have undergone cardiopulmonary bypass during the formative years of that technology. In addition, some patients have syndromes in which congenital heart disease and mental disability are associated (e.g., Down syndrome). Anxiety and depression are also relatively common and may be exacerbated by admission to the ICU.

Cyanotic Heart Disease

Chronic cyanosis leads to polycythemia, plethora, and finger clubbing. Patients with cyanosis have a tendency toward increased bleeding due to thrombocytopenia, platelet dysfunction, and reduced levels of certain clotting factors (including protein C and protein S). Spontaneous bleeding is usually mucocutaneous and mild, but life-threatening hemorrhage, particularly pulmonary hemorrhage, can occur occasionally.

The presence of right-to-left intracardiac shunting increases the risk for cerebral embolic events. Until recently, it was accepted that polycythemia itself was a risk factor for stroke. This belief led to the widespread use of phlebotomy to control hematocrit, typically to less than 55%. More recently, the detrimental effects of phlebotomy on oxygen delivery and iron stores have been appreciated,⁵ and many centers now reserve phlebotomy for patients with symptomatic polycythemia. The increased red cell turnover associated with polycythemia predisposes to the development of gallstones and gout. The risk for gout is increased by concomitant renal dysfunction and the use of diuretics.

General Perioperative Considerations

In addition to a thorough cardiac assessment, preoperative evaluation must include consideration of other organ systems (see earlier discussion, Multisystem Disease). Respiratory function tests may be indicated for patients who have undergone multiple previous cardiac operations. Patients who are older than 40 or have risk factors for coronary artery disease should undergo coronary angiography. For patients who have cyanosis with thrombocytopenia, careful preoperative phlebotomy can promote hemostasis by initiating a temporary increase in platelet numbers. When the hematocrit exceeds 55%, increased citrate must be added to the tubes that are used for coagulation testing.

Patients have usually undergone multiple arterial and venous catheterizations. Thus, vascular access may be difficult, and there may be thrombosis and occlusion of central veins and arteries. Prior exposure to blood products may have led to antibody formation, creating difficulties in cross-matching blood for transfusion. For patients with right-to-left shunts it is essential to avoid all air bubbles in venous lines because they can embolize systemically.

Most surgeries performed for congenital heart disease in adults are reoperations, and in many cases cardiopulmonary bypass times are long. Conduits from previous operations may be located directly behind the sternum and can be damaged during sternotomy. Postoperative problems involving excessive bleeding, coagulopathy, myocardial stunning, and pulmonary hypertension are not uncommon. Chronic volume and pressure overload of the cardiac chambers, along with scarring from previous surgeries, predispose to the development of ventricular dysfunction and arrhythmias. Poor nutritional state, chronic hypoxemia, and low cardiac output contribute to poor wound healing and the occurrence of nosocomial infection. Adults with congenital heart disease are at increased risk for developing endocarditis (see Table 10-7) and require antibiotic prophylaxis prior to certain invasive procedures (see Endocarditis Prophylaxis in Chapter 10). If these patients become febrile it is essential to draw blood cultures prior to commencing antibiotic treatment.

Tetralogy of Fallot

The essence of the tetralogy of Fallot (Fig. 15-1) is anterior displacement of the conal septum. This results in obstruction of the right ventricular outflow tract (RVOT) and a ventricular septal defect (VSD) and causes the aorta to override the crest of the ventricular septum. RVOT obstruction and right ventricular volume loading cause right ventricular hypertrophy, which is the fourth feature of the tetralogy. RVOT obstruction in the presence of a VSD causes a variable degree of right-to-left shunting and hypoxemia. Patients usually present in infancy with a murmur. If right ventricular outflow obstruction is severe, patients become cyanotic and may experience hypercyanotic “spells.”

Figure 15.1 Tetralogy of Fallot. The ventricular septal defect, aortic override, right ventricular outflow tract obstruction, and right ventricular hypertrophy together constitute the tetralogy of Fallot. Ao, aorta; IVC, inferior vena cava; LV, left ventricle; PA, pulmonary artery; RV, right ventricle; SVC, superior vena cava.

A tetralogy of Fallot was first palliated in 1944 by the classical Blalock-Taussig shunt. In this procedure, the subclavian artery is transected and anastomosed directly onto the pulmonary artery. Additional palliative strategies have included the Waterston and Potts shunts, in which the aorta (ascending or descending, respectively) is anastomosed side-to-side to a branch pulmonary artery. A modified version of the Blalock-Taussig shunt, in which a tube graft is used to connect the right subclavian artery to the right pulmonary artery (Fig. 15-2), is still performed to palliate lesions in which pulmonary blood flow is inadequate.

Figure 15.2 Modified Blalock-Taussig shunt for tetralogy of Fallot. A Gore-Tex shunt is inserted between the right subclavian artery and the right pulmonary artery. This improves blood flow to the pulmonary vascular bed. Ao, aorta; IVC, inferior vena cava; LV, left ventricle; PA, pulmonary artery; RV, right ventricle; SVC, superior vena cava.

In the 1950s a more complete repair of the tetralogy of Fallot was developed. Repair involves patch closure of the VSD and reconstruction of the obstructed RVOT (Fig. 15-3); the latter is commonly achieved by placing a patch across the annulus of the pulmonary valve, rendering it incompetent. Patients usually undergo surgical correction in early childhood; depending on institutional practice and the presence and severity of cyanosis, it may have been preceded by a Blalock-Taussig shunt in infancy. Long-term survival rates are excellent. However, free pulmonary regurgitation causes right ventricular overload, which can eventually lead to right ventricular failure and ventricular arrhythmias. Patients who have undergone repair of a tetralogy of Fallot are at increased risk for sudden death, and those with ventricular tachyarrhythmias should be considered for internal cardiac defibrillators. Pulmonary valve replacement can prevent these problems, although there is disagreement about the optimal timing of surgery. Most centers use a combination of symptoms, measured exercise tolerance, and quantitative assessment of right ventricular function (usually by means of a magnetic resonance imaging scan) to establish the need for pulmonary valve replacement.

Figure 15.3 Tetralogy of Fallot after repair. This operation consists of patch repair of the ventricular septal defect (VSD) and relief of the right ventricular outflow tract obstruction, often with a transannular patch. Ao, aorta; IVC, inferior vena cava; LA, left atrium; LV, left ventricle; PA, pulmonary artery; RA, right atrium; RV, right ventricle; SVC, superior vena cava.

Conduit Replacement

In addition to the tetralogy of Fallot, a number of other surgically corrected defects may require replacement of a valved conduit, usually to create a competent pulmonary outflow. Examples include truncus arteriosus and pulmonary atresia. Perioperative issues are similar to those described earlier.

Fontan Procedures

Three decades after its original description, the Fontan operation (or one of its modifications) remains the primary means of palliation for the functionally univentricular heart. These procedures involve diverting the systemic venous return directly to the pulmonary arteries without passing through a pumping chamber, while the ventricular complex acts as the systemic pump. This arrangement results in a divided circulation and a “pink” patient. However, pulmonary blood flow, on which cardiac output depends, is passive because it is dependent on the transpulmonary pressure gradient and pulmonary vascular resistance.

The classical Fontan operation, first described for tricuspid atresia (Fig. 15-4), involved connecting the right atrial appendage directly to the pulmonary artery and closing the interatrial communication (Fig. 15-5). This operation provides good initial palliation, but over time, right atrial dilatation develops, resulting in persistent atrial arrhythmias.^6–8 Patients are also at risk for developing right atrial thrombi and pulmonary emboli which, in a circulation that relies on passive blood flow through the pulmonary circulation, are very poorly tolerated. Additionally, right atrial dilatation can cause compression of the right-sided pulmonary venous return, contributing to impaired cardiac function.

Figure 15.4 Tricuspid atresia with normally related great arteries. In tricuspid atresia, an atrial septal communication and a ventricular septal defect are usually present. Tricuspid atresia is also commonly associated with pulmonary stenosis or pulmonary atresia. Ao, aorta; IVC, inferior vena cava; LA, left atrium; LV, left ventricle; PA, pulmonary artery; RA, right atrium; RV, right ventricle; SVC, superior vena cava.

Figure 15.5 Right atrial-to-pulmonary artery Fontan procedure for tricuspid atresia with normally related great arteries. In this procedure the systemic venous return is channeled to the pulmonary circulation by anastomosing the right atrial appendage to the pulmonary artery. If there is residual flow through the pulmonary valve, the main pulmonary artery is usually ligated at the time of operation. The atrial septal communication is repaired. Ao, aorta; IVC, inferior vena cava; LA, left atrium; LV, left ventricle; PA, pulmonary artery; RA, right atrium; RV, right ventricle; SVC, superior vena cava.

Because of these complications, a number of modifications to the classical Fontan operation have been introduced, including the lateral tunnel (Fig. 15-6) and extracardiac (Fig. 15-7) techniques, with the aim of streamlining venous return to the lung and minimizing atrial scarring. These modifications, in particular the extracardiac Fontan, have become the procedures of choice for children currently undergoing single-ventricle palliation.

Figure 15.6 Lateral tunnel Fontan procedure for tricuspid atresia with normally related great arteries. In this procedure systemic venous return is channeled into the pulmonary circulation by direct anastomosis of the superior vena cava onto the right pulmonary artery, and from the inferior vena cava to the right pulmonary artery by way of an intraatrial baffle. If there is residual flow through the pulmonary valve, the main pulmonary artery is ligated at the time of operation. Ao, aorta; IVC, inferior vena cava; LA, left atrium; LV, left ventricle; PA, pulmonary artery; RV, right ventricle; SVC, superior vena cava.

Figure 15.7 Extracardiac Fontan procedure for tricuspid atresia with normally related great arteries. This procedure is similar to the lateral tunnel Fontan procedure, except that the systemic venous return from the inferior vena cava is returned to the right pulmonary artery via an extraatrial conduit. Ao, aorta; IVC, inferior vena cava; LA, left atrium; LV, left ventricle; PA, pulmonary artery; RV, right ventricle; SVC, superior vena cava.

Prior to the Fontan operation, most children undergo at least two previous operations. The first of these is usually performed in infancy and is typically one of the following:

After this initial operation, most children then undergo a bidirectional Glenn (Fig. 15-8) or hemi-Fontan procedure at between 3 and 9 months of age. These procedures direct superior vena caval blood directly to the pulmonary arteries. Patients remain cyanotic following this procedure, with oxygen saturations usually in the mid 80s. The Fontan operation itself is usually performed in the preschool years.

Figure 15.8 Bidirectional Glenn shunt for tricuspid atresia with normally related great arteries. In this procedure the systemic venous return from the SVC is directed into the pulmonary circulation by direct anastomosis of the SVC onto the RPA. If the main pulmonary artery is not congenitally occluded (pulmonary atresia) it is usually surgically ligated as part of this procedure. Ao, aorta; IVC, inferior vena cava; LA, left atrium; LV, left ventricle; PA, pulmonary artery; RPA, right pulmonary artery; RV, right ventricle; SVC, superior vena cava.

Coarctation of the Aorta

Coarctation of the aorta most commonly occurs in proximity to the point of entry of the ductus arteriosus to the descending aorta (Fig. 15-9). The narrowing can be discrete or associated with aortic hypoplasia. Coarctation of the aorta can occur as an isolated abnormality or in association with congenital heart disease, most commonly bicuspid aortic valve. Severe coarctation usually presents in infancy but milder degrees can present for the first time in adulthood, usually with systemic hypertension. Patients can also develop recurrent coarctation at the site of a previous repair.

Figure 15.9 Congenital coarctation of the aorta. This condition usually occurs distal to the left subclavian artery at the level of the ductus arteriosus ligament. Ao, aorta; PA, pulmonary artery.

In infancy and childhood, most coarctations are repaired by end-to-end anastomosis. An alternative technique is the use of a subclavian flap, in which the subclavian artery is divided and turned down adjacent to the descending aorta to be used as a patch to bridge the narrowed segment. Patients who have undergone this procedure will have weak or absent pulses in the left arm. The use of Dacron interposition grafts or patch aortoplasty for repair in children is associated with the development of aortic aneurysms in later life. Aortic coarctation that presents in adulthood can usually be managed by percutaneous balloon dilation and stent placement, but occasionally open surgical repair is required.

Secundum Atrial Septal Defects

Secundum atrial defects (ASDs) are classified according to their locations, hence, according to their embryologic origins. Secundum ASDs develop within the oval fossa because of a deficiency in the septum primum. They are of variable size and may be multiple. Secundum ASDs are usually diagnosed in childhood, but because the clinical signs are subtle and the defect initially asymptomatic, first presentation in adulthood is not unusual.

ASDs result in left-to-right interatrial shunting and right ventricular volume overload. (In contrast, VSDs are associated with left ventricular dilatation and congestive cardiac failure.) Patients present with the gradual onset of exertional dyspnea, fatigue, and atrial arrhythmias. There may be fixed wide splitting of the second heart sound, a right ventricular heave, and a systolic flow murmur. Rarely, large defects are associated with the development of severe pulmonary hypertension and Eisenmenger syndrome. However, severe pulmonary hypertension is not a routine consequence of interatrial shunting and if it is present, other causes should be sought.

Centrally placed defects can usually be closed by percutaneous, TEE-guided, transcatheter device occlusion. However, defects that are eccentrically located, very large, or multiple typically require surgical closure. In patients who develop problematic atrial arrhythmias, surgical closure and concomitant maze procedures may be the preferred treatment option.

Transposition of the Great Arteries

Transposition of the great arteries is a condition in which the connections of the great arteries are reversed so that the aorta arises from the right ventricle and the pulmonary artery from the left ventricle. The current approach to surgical correction is the arterial switch procedure, which results in anatomically normal circulation. However, most adult patients with transposition have previously undergone palliative atrial switch procedures. They include the Senning and Mustard procedures (Fig. 15-10), in which baffles are inserted within the atria to redirect the pulmonary and systemic venous return. The systemic venous return is redirected to the anatomic left ventricle and then to the pulmonary artery; the pulmonary venous return is redirected to the anatomic right ventricle and then to the aorta. In this way, a functionally normal circulation is obtained, but the anatomic right ventricle remains as the systemic ventricle. These operations provide excellent initial palliation. However, over the longer term two important problems typically develop. First, the systemic right ventricle gradually fails, resulting in congestive cardiac failure; and second, atrial arrhythmias become a growing problem.

Figure 15.10 Mustard procedure for transposition of the great arteries. In this procedure a baffle system in the right atrium directs systemic venous blood from the superior and inferior vena cavae across to the mitral valve, from which it passes through the (anatomic) left ventricle to the pulmonary artery. Pulmonary venous blood is directed across to the tricuspid valve and from there passes to the (anatomic) right ventricle into the aorta. Ao, aorta; LV, left ventricle; PA, pulmonary artery; RV, right ventricle.

Some centers have performed late arterial switch, usually in the first decade or early teenage years, in patients who have undergone Senning or Mustard procedures.⁹ The main problem limiting a more general application of this approach is that the anatomic left ventricle, having been the pulmonary pump since birth, may be unable to function as the systemic ventricle following anatomic correction. Sequential pulmonary artery banding usually precedes arterial switch in an attempt to “train” the anatomic left ventricle to tolerate an increased afterload. The major postoperative problem is left ventricular failure.

Some patients with failing Senning or Mustard procedures undergo heart transplantation. For patients with atrial switch who develop AV valve regurgitation, a valve repair procedure may be indicated.

Atrioventricular Canal Defects

Defects of the central portion of the heart are referred to as AV canal defects. They consist of a spectrum of diseases and may be categorized as partial, intermediate, or complete. Partial defects consist of an ostium primum ASD and a mitral cleft. Intermediate defects consist of an ostium primum ASD, a VSD, and separate, but abnormal, AV valves. Complete AV canal defects consist of an ostium primum ASD, a VSD, and a common AV valve. There is left-to-right shunting and AV valve regurgitation, which cause a variable degree of pulmonary hypertension and congestive heart failure. AV canal defects are usually repaired in childhood. Failure to achieve early repair of defects with a significant ventricular component can result in severe pulmonary hypertension and, potentially, Eisenmenger syndrome. Patients may present in late childhood or adulthood for AV valve repair or replacement and can have significant pulmonary hypertension and ventricular dysfunction.

Eisenmenger Syndrome

An uncorrected cardiac lesion with a large left-to-right shunt and high pulmonary blood flow (usually more than twice normal) produces increased pulmonary vascular resistance and pulmonary hypertension. Initially, the increase in pulmonary vascular resistance is reversible, but over time it may progress to irreversible pulmonary vascular occlusive disease. The classical condition in which this occurs is a VSD, but it can occur in any condition with a high pulmonary blood flow, such as AV canal defect, truncus arteriosus, aortopulmonary window, and patent ductus arteriosus.

The Eisenmenger syndrome is a condition in which pulmonary vascular occlusive disease has developed to the point where pulmonary vascular resistance exceeds systemic vascular resistance. When this happens, shunt flow reverses, becoming right-to-left, and progressive hypoxemia develops. Right-to-left shunting partly protects the right ventricle from further increases in pulmonary vascular resistance. At this point surgical repair is no longer possible because it would precipitate acute right ventricular failure.

Patients with Eisenmenger syndrome can be remarkably stable for a number of years before becoming increasingly symptomatic, usually between the third and fifth decades of life. Modes of death include congestive heart failure, infection, and hemoptysis. Pregnancy carries a high mortality rate and is contraindicated. In certain circumstances, lung or heart-lung transplantation may be considered.

Patients with Eisenmenger syndrome occasionally require noncardiac surgery or intensive care treatment. The principles of management include avoiding acute increases in pulmonary vascular resistance and decreases in systemic vascular resistance and supporting right ventricular function. Abrupt increases in pulmonary vascular resistance, for instance due to hypercarbia or acidosis, cause profound hypoxemia and may precipitate acute right heart failure. Support of right ventricular function and control of pulmonary vascular resistance are discussed in Chapters 20 and Chapter 24, respectively.