	Life-Threatening^∗	Not Life-Threatening
Arrhythmia	AF with bypass tract Atrial flutter Mustard Frontan CHB with hypotension or CHF and/or ventricular escape Ventricular tachyarrhythmias with symptoms	AF without bypass tract CHB: normal hemodynamics and nodal escape Isolated PVCs Asymptomatic, nonsustained VT
Ischemia	Ongoing chest pain with ischemic ECG changes	Chronic nonischemic chest pain
Ventricular failure	New murmur + fever Compromising pleural effusion or ascites
Cyanosis	Loss of continuous murmur in patient with BT or central shunt Acute pulmonary infection	Chronic cyanosis
Noncardiac	Hemoptysis Transient ischemic attacks or seizures (new onset)	Gout Biliary colic

Abbreviations: AF, atrial fibrillation; BT, Blalock-Taussig shunt; CHB, complete heart block; VT, ventricular tachyarrhythmias.

∗ Warrants admission to CICU.

There are emergencies that are unique to the patient with congenital heart disease: For example, the occurrence of pregnancy in the patient with Eisenmenger syndrome. The drop in systemic vascular resistance in these patients increases the right-to-left shunt and results in arterial desaturation. However, most emergent complications seen in congenital heart disease are similar to the emergency situations seen in cardiovascular problems of other more common etiologies. The diagnosis of ventricular tachycardia in a patient with repaired tetralogy of Fallot is treated in a manner similar to the patient with coronary disease and ventricular tachycardia and, unfortunately, with the same uncertain efficacy. It is important to remember that a patient with repaired tetralogy of Fallot is at risk of developing ventricular tachycardia and to recognize the importance of investigating palpitation and presyncope and syncope. Substantial analogies to the care of general cardiac patients exist, but this needs to be combined with knowledge of what complications to expect with what lesion and management needs to be tailored to a congenital patient’s unique anatomy (Table 34-2).

Table 34–2 Complications of Congenital Heart Disease

Lesion	Special Considerations
Tetralogy of Fallot	Ventricular tachycardia Atrial fibrillation Right ventricular dysfunction Pulmonary regurgitation (late complication usually associated with moderate to severe regurgitation)
Fontan	Ventricular dysfunction Sinus node dysfunction Atrial flutter/intra-atrial re-entrant tachycardia (IART) Fontan obstruction or leak Pulmonary embolus
D-transposition of great arteries	Atrial flutter/IART Systemic right ventricular dysfunction AV block (uncommon late) Baffle systemic AV valve regurgitation Sinus node dysfunction with junctional rhythm (usually asymptomatic)
L-transposition of great arteries	Systemic ventricular failure AV block Systemic AV valve regurgitation WPW (2%-4%)
Coarctation	Dissection Bicuspid valve with endocarditis, regurgitation, or stenosis Early coronary artery disease or heart failure Cerebral aneurysm
Left-to-right shunt	Pulmonary hypertension (Eisenmenger syndrome) Atrial fibrillation Endocarditis (VSD or PDA, rare with ASD)
Right-to-left shunt (cyanotic)	Paradoxical embolus Worsening cyanosis Brain abscess Bleeding diasthesis Hyperviscosity syndrome with erythrocytosis Protein-losing enteropathy
Marfan	Dissection Aortic valve regurgitation Mitral valve prolapse

In the patient with a cardiac emergency, congenital heart disease can predispose the patient to certain complications that may be responsible for the cardiac emergency. For example, in a patient with L-transposition of the great vessels and shortness of breath, the right ventricle is acting as the systemic ventricle and is prone to failure. The diagnosis of heart failure is not difficult, and treatment of congestive heart failure in these patients is similar to the treatment of congestive heart failure in those with other conditions.

Anatomic and Pathophysiologic Classification of Congenital Heart Disease

During the formation of the heart and cardiovascular system, there are many opportunities for the development of the lesions of congenital heart disease. The large variety of lesions forming the body of congenital heart disease can be confusing. It is helpful for the cardiologist seeing adult patients to think of these lesions in an organized manner. The following classification is helpful in that all congenital heart patients fit into one or more of these categories.

1. Predominant left-to-right shunt. Blood that has gone through the lungs, recirculates to the right side of the heart, and as a result the pulmonary blood flow is greater than the systemic blood flow. The shunt can occur at any level (e.g., at the venous level, anomalous pulmonary vein to the superior vena cava; at the atrial level, ASD; at the ventricular level, VSD; at the arterial level, PDA).

2. Predominant right-to-left shunt, or “cyanotic disease.” The blood is shunted from the right heart to the systemic circulation, bypassing the lungs. The arterial blood is therefore desaturated. If the amount of desaturated hemoglobin is 5 g/dL or greater, cyanosis can be observed. The systemic blood flow is greater than the pulmonary blood flow. This shunt also can occur at any level of the cardiovascular system (e.g., at the venous level, superior vena cava draining into the left atrium; at the atrial level, tricuspid atresia with an ASD; at the ventricular level, tetralogy of Fallot; at the arterial level, truncus arteriosus).

3. Stenotic or atretic valves and hypoplastic or atretic ventricles. The valves can also be incompetent. Either ventricle may be hypoplastic or atretic.

4. Great vessel abnormalities. Transposition of the great vessels, coarctation of the aorta, PDA, vascular rings, and truncus arteriosus.

5. Abnormalities of position. Transposition of the great vessels, L-transposition, dextroposition, and dextrocardia.

Arrhythmias

Arrhythmias are some of the more common emergencies seen in patients with congenital heart disease. There are two types of arrhythmias: bradyarrhythmias (e.g., sick sinus syndrome, sinus arrest, varying degrees of heart block including complete heart block) and tachyarrhythmias (e.g., atrial fibrillation, atrial flutter, ventricular tachycardia, and fibrillation).

The arrhythmic patient may have palpitations, presyncope, or syncope. With atrial tachyarrhythmias, the patient usually complains of palpitations, which sometimes are severe enough to frighten the patient. Presyncope or syncope occurs with extremely rapid ventricular response, raising pulse rates to 200 beats/min or more. If the left ventricle is noncompliant with an atrial tachyarrhythmia, especially atrial fibrillation—in which there is no atrial contraction—stroke volume can fall dramatically, and the patient may develop syncope. The diagnosis of this type of arrhythmia can be made by electrocardiogram (ECG) if the arrhythmia is persistent. However, even if the patient having syncope or presyncope is in sinus rhythm at the time of the examination, it is most important to consider the patient with congenital heart disease, with or without repair, as having a potentially fatal arrhythmia.

The atrial bradyarrhythmias and tachyarrhythmias encountered in patients with congenital heart disease may result from hemodynamic alterations of the atrium or involve areas of slowed conduction in the areas of scar associated with prior surgery. These may include surgery for ASD repair,³ both ostium secundum and ostium primum defects, Fontan procedures for tricuspid atresia or single ventricle,^4,⁵ and the Mustard or Senning procedure for transposition of the great arteries.^6,⁷

Lesions affecting the conduction system and causing AV block have become less common since surgeons have learned to avoid the conduction system during surgery. However, with any VSD repair, immediate injury or later injury as a result of fibrosis is a possible cause of progressive heart block. With advances in surgical technique and knowledge of the path of the conduction system, heart block after repair of VSD is increasingly rare with persistent heart block seen in less than 1% of patients.⁸

L-transposition, or corrected transposition of the great vessels, is a lesion in which ventricular inversion has occurred without inversion of the atria or great arteries. In this condition, the anatomic right ventricle is the systemic ventricle and the anatomic left ventricle is the pulmonic ventricle, but the physiologic passage of blood is normal (i.e., the systemic venous return is pumped to the lungs, and the pulmonary venous return is ejected into the aorta). The conduction system is also inverted and the AV node is abnormally located and often dual with elongation of the bundle of His.⁹ As a result, these patients have a high rate of AV block, which can occur at all levels of severity—from first to third degree—and which increases in incidence with age at a rate of about 1% to 2% per year.

Atrial Tachyarrhythmias

The diagnosis and treatment of bradyarrhythmias and tachyarrhythmias are the same in patients with congenital heart disease as for those with other lesions. When symptomatic bradycardia and hemodynamic instability, such as hypotension or syncope, are present, a pacemaker is indicated.

Atrial fibrillation, tachycardia, and flutter, when they occur in patients with congenital heart disease, are usually relatively not life-threatening.^10,¹¹ These arrhythmias occur in about 20% of patients with ASDs and can recur even after the ASD is repaired, especially when the repair is performed late in life (after the age of 40).³ In some defects, atrial fibrillation or atrial flutter can be very serious and even life-threatening. The treatment is similar to that of atrial fibrillation or atrial flutter due to other causes; with rapid atrial tachycardia in patients with hemodynamic instability, immediate cardioversion is indicated. In patients who are hemodynamically stable with noncontracting atria, which may be seen in conditions such as atrial fibrillation and atrial standstill, anticoagulation therapy for 3 weeks before cardioverting is indicated. In such cases, the patient should receive anticoagulation for 3 weeks after cardioversion until mechanical atrial contraction is well established. If the patient is hemodynamically stable, the ventricular response can be slowed with amiodarone, β-blockers, verapamil, or diltiazem. If it is necessary to cardiovert before achieving stability, a period of anticoagulation can be provided. Transesophageal echocardiography (TEE) to rule out evidence of atrial thrombus is desired and allows safe cardioversion. With atrial tachycardia, 6 mg adenosine given intravenously usually converts the patient to sinus rhythm. If this treatment is unsuccessful, another 6 to 12 mg of adenosine can be given.

Atrial flutter or intra-atrial re-entrant tachycardia occurs frequently in patients who have undergone a Fontan procedure, with the prevalence estimated as high as 50% in adult patients. The presentation is usually subacute but occasionally hemodynamic instability and even sudden death especially in the setting of 1:1 conduction.¹² The patient should be converted to normal sinus rhythm either pharmacologically or by cardioversion with the caution that antiarrhythmics may exacerbate sinus node dysfunction, AV conduction, or promote 1:1 conduction of an atrial arrhythmia. If atrial flutter recurs, the patient should be referred to an electrophysiologist to map the pathways of flutter, if possible. If this can be done, catheter ablation of the pathway is possible. If atrial flutter or atrial tachycardia recurs incessantly and ablation attempts fail, then ablation of the AV node with placement of a dual-chamber (DDD) pacemaker should be considered. If the patient does not remain in sinus rhythm, then a physiologically responsive (VVIR) pacemaker is the treatment of choice.

Another atrial arrhythmia that can be fatal is atrial tachycardia and subsequent atrial fibrillation in a patient with an antegrade conducting bypass tract. In this condition, the impulse conducts from the atrium to the ventricle over the bypass tract. Especially with sympathetic stimulation or increased conductivity induced by digitalis, the ventricular response can approach 250 to 300 beats/min, and the patient may develop ventricular fibrillation. In patients with a possible AV bypass tract, digoxin should always be avoided. Patients with Ebstein anomaly have 25% incidence of bypass tracts in the posteroseptal location and a bypass tract may be present in 2% to 4% of patients with L-TGA.

In patients with atrial fibrillation and an AV bypass tract (i.e., Wolff-Parkinson-White syndrome), digoxin should always be avoided. In these patients, the ventricular response is controlled with a β-blocker or calcium channel blocker. When present, the AV bypass tract should be ablated.

Ventricular Tachyarrhythmias

Ventricular tachyarrhythmias can occur as a result of incisions in the right or left ventricle with fibrous scar forming the basis for re-entrant arrhythmias or more commonly with progressive ventricular enlargement with decreased left or right ventricular function, or a hypertrophied left or right ventricle.

The development of ventricular tachyarrhythmias late after surgery is not uncommon. This is especially true in patients with tetralogy of Fallot; sudden death later after surgery is seen in about 6% of patients in long-term follow-up.¹³ Late sudden death and ventricular arrhythmias in tetralogy correlate well with the degree and duration of pulmonary regurgitation, with arrhythmias increasing as continued pulmonary regurgitation results in progressive right ventricular enlargement.¹⁴ As the right ventricle enlarges, there is increased fibrosis, QRS prolongation, and Q–T dispersion that appears to provide the substrate for ventricular tachycardia.^15,¹⁶ Fortunately, it appears that timely pulmonary valve replacement may decrease the incidence of arrhythmias.¹⁷

The patient may have palpitations, presyncope, or syncope. The diagnosis of ventricular tachycardia can be made on ECG, either on presentation or on the 24-hour ambulatory ECG. If the arrhythmia is frequent but short-lived, an event recorder, which allows continuous ECG monitoring and activating capture of the rhythms when symptoms occur, can be worn for several days.

Any patient with congenital heart disease, either before or after surgery, with presyncope or syncope must be considered as having had a potentially life-threatening arrhythmia. In such patients, if the diagnosis cannot be made on an ECG, electrophysiologic testing should be considered for prognostication and to potentially assist with therapy. As with degenerative cardiac disease, antiarrhythmic therapy has not been shown to be of life-sustaining benefit in congenital heart disease, although it may be important for symptom control. The use of an implantable cardioverter-defibrillator (ICD) should, therefore, be considered in patients considered at high risk for sudden death. Randomized trials of congenital heart patients, however, do not exist to guide selection.

Ischemic Complications

In adult patients with congenital heart disease, ischemic complications causing cardiac emergencies are rare. More commonly, the anomalous origin of the left coronary artery from the pulmonary artery causes acute severe ischemia and myocardial infarction in infants who usually have heart failure due to an extensive anterolateral myocardial infarction. Occasionally, the murmur of mitral regurgitation or “angina” manifested by poor feeding or suckling or crying at times of exertion (such as feeding) and consequently brings the infant to the attention of the physician. By the age of 1 year, most of these children have been diagnosed or died.

The potential reasons for the occurrence of myocardial ischemia in adults with congenital heart disease include the following:

1. Anomalous left coronary artery arising from a pulmonary artery (ALCAPA) with late presentation or with complications resulting after repair in infancy.

2. A left coronary artery arising from the right sinus of Valsalva or the right coronary artery arising from the left sinus of Valsalva when these malformations are associated with an interarterial course between the aorta and the pulmonary artery.

3. Coronary arteries transposed in the arterial switch operation for transposition of the great vessels, with subsequent compromise.

4. Coronary aneurysm, with congenital or postinflammatory, such as Kawasaki disease or panarteritis nodosa with associated thrombosis.¹⁸

5. Coronary artery compressed by myocardial muscle bridge.

6. Coronary arteriovenous or coronary-cameral fistula.

7. Aortic stenosis with myocardial ischemia or pulmonary stenosis with right ventricular ischemia.

Rarely, the cardiologist sees an adult patient with a coronary artery anomalously arising from the pulmonary artery that was transplanted or repaired with a tunnel repair, or occasionally, with simple ligation of the left coronary artery. Prior to surgical repair, when the entire coronary circulation is dependent on the right coronary artery and collaterals, patients can develop progressive ischemia with growth, resulting in angina or heart failure. If there are symptoms or signs consistent with myocardial ischemia, the patient should have an estimation of ventricular function by echocardiography or radionuclide scanning and some measure of myocardial viability by positron emission tomography, dobutamine echocardiography, or resting thallium-201 scanning. If ischemic myocardium is found, then revascularization of the left coronary artery should be performed.

Rarely, adult patients have unrepaired ALCAPA. Presentations include ischemia, sudden death, dilated cardiomyopathy with heart failure, and progressive mitral regurgitation. Extensive collateral flow from a dilated coronary right artery permits survival into adulthood but the resulting left-to-right shunt and a coronary steal place a significant hemodynamic burden on the left ventricle. Prompt repair is indicated.

An uncommon condition causing myocardial ischemia is the left coronary artery arising from the right sinus of Valsalva. This lesion may not, and probably usually does not, cause myocardial ischemia in most patients. However, in some patients, usually young adults, most often during or just after exercise, sudden and usually transient occlusion of the left coronary artery can occur. This causes profound ischemia to the left ventricle and is usually manifested by sudden death or syncope and occasionally by profound angina, with or without myocardial infarction.

The reason for the sudden ischemic episode is not known. The usual course of such a vessel is obliquely posterior, between the right ventricular outflow tract and the aortic root. This could result in a kinking or compression of the artery during exercise, or possibly in collapse of the orifice of the coronary ostium. However, coronary spasm cannot be ruled out. This type of event occurs only rarely because patients on many previous occasions have exercised as or more vigorously without difficulty. Furthermore, in a few patients who have exercised after an event has occurred, frequently no ischemia can be precipitated.

Less commonly, the right coronary artery arises from the left sinus of Valsalva and causes sudden death, syncope, or inferior myocardial infarction. This is less often a cause of sudden death because sudden occlusion of the right coronary artery generally leads to inferior myocardial infarction.

Any patient under age 30 years who has presyncope or syncope during exercise or a life-threatening ventricular arrhythmia with an apparently normal heart on echocardiogram should be suspected of having an anomalous origin of the left or right coronary artery from the opposite sinus of Valsalva. At present, cardiac CT and MRI may provide the best spatial resolution to define coronary anomalies ¹⁹; however, transesophageal echocardiography (TEE)²⁰ or definitive identification with invasive catheterization can be useful. If such an anomaly is identified, bypass grafting should be considered.

Heart Failure in the Adult with Congenital Heart Disease

The underlying mechanisms for the development of congestive heart failure in the setting of congenital heart disease are similar to those in acquired disease. Broadly defined, congestive heart failure can result from:

1. Primary pump failure involving either the right or left ventricle.

2. Ventricular hypertrophy and fibrosis leading to diastolic dysfunction.

3. Mechanical dysfunction, usually on the basis of valvular disease or failure of palliative procedure.

The onset of heart failure in adults with congenital heart disease is usually gradual; thus patients usually have chronic or subacute symptoms. Acute presentations are most common in those with sudden valvular incompetence, ischemia (discussed previously), new onset of arrhythmia, or sudden exacerbations of chronic congestive heart failure. Identifying the cause of congestive heart failure in these patients requires an accurate and detailed clinical history and physical examination, a systematic noninvasive evaluation, and frequently a referral for an invasive hemodynamic evaluation when information remains incomplete.

The clinical history is an essential key in diagnosing the cause of heart failure in adults with congenital heart disease. Critically important are knowledge of the primary lesion and the presence of associated lesions. One example is coexistence of a bicuspid aortic valve that becomes clinically manifest with stenosis or insufficiency many years following a repair for aortic coarctation. Second, the timing and nature of both palliative procedures and surgical repairs strongly influence late manifestations. Occasionally, a palliative procedure may produce residua long after primary repair has been performed; for example, congenital aortic stenosis treated with surgical valvotomy may have recurrent stenosis or progressive aortic regurgitation. Third, the specific procedure performed to achieve the primary repair influences late outcome; for example, a patch placed across the pulmonary annulus (i.e., transannular) to alleviate pulmonary stenosis in teratology of Fallot is associated with progressive pulmonary insufficiency, whereas other procedures are more likely associated with residual stenosis. Finally, the development of acquired disease may influence the natural history of congenital heart disease, such as accelerated atherosclerotic coronary disease in patients with coarctation of the aorta.

The physical examination should be directed toward identifying signs of systemic venous congestion (e.g., elevated jugular venous pressure, leg edema, ascites, pleural effusion) and pulmonary venous congestion (e.g., pulmonary rales). Evidence of ventricular enlargement will be evident on precordial palpation, but the right and left ventricles may be transposed. Murmurs of valvular stenosis and insufficiency should be carefully noted. When present, prosthetic valve sounds should be crisp and constant in their intensity; dampened or irregular clicks may reflect valve dysfunction or arrhythmia. The absence of a continuous murmur in a patient with a Blalock-Taussig shunt may herald obstruction or pulmonary vascular disease and explain worsening cyanosis.

The approach to the noninvasive diagnosis of heart failure in the adult with congenital heart disease is similar to that for patients with acquired disease, except that knowledge of the anatomy unique to the primary congenital lesion and to the surgical repairs is required. Inspection of the ECG for conduction defects and arrhythmias occasionally reveals the cause of heart failure. Echocardiography should be considered early in the presentation of these individuals, with the following specific goals:

1. Establishing or confirming the primary and secondary diagnoses.

2. Establishing the adequacy of prior surgical repairs, including patch competency and shunt patency.

3. Evaluating ventricular systolic and diastolic function.

4. Identifying hemodynamically significant valvular dysfunction, either native or prosthetic, and intracardiac shunts.

TEE may be superior to surface imaging, especially in evaluation of the atria, interatrial septum, conduits, and prosthetic valves. Although it is a semi-invasive procedure, TEE has proven safe in critically ill patients once respiratory status is stabilized. Cardiac MRI and CT may be helpful as well, providing both a cardiac assessment and helping delineate extracardiac pulmonary anatomy; however, both procedures may be difficult in unstable patients.

When the clinical and noninvasive data are inconclusive, and specifically, to exclude superimposed disease, cardiac catheterization may be necessary. It is important that the goals of the study be predetermined and that the catheterization be performed by personnel familiar with congenital heart disease. Incomplete information can lead to inappropriate treatment.

Etiologies of Pump Failure

There are several causes of pump failure unique to the population of adults with congenital heart disease. The right ventricle functioning in the systemic circulation is encountered in two groups of patients: those with congenitally corrected transposition of the great arteries (L-transposition), and those with transposition of the great vessels palliated with an interatrial baffle operation (i.e., Mustard or Senning procedure). Although the right ventricle hypertrophies and is thus able to pump against the increased afterload for many years, late failure is a feature of the natural history of the patient population usually presenting in the fourth or fifth decade of life.²¹ The signs and symptoms are those of pulmonary congestion and occasionally low output. It is necessary to exclude obstruction of the pulmonary venous limb of the interatrial baffle, which may also lead to pulmonary venous congestion and be confused with failure of the systemic ventricle. Likewise, systemic venous congestion may occur in the presence of obstruction to the systemic venous limb of the baffle. These structural lesions may require percutaneous intervention or surgery. Precipitants should be identified such as incessant atrial tachyarrhythmias, which can lead to ventricular dysfunction. Occasionally excessive alcohol use or superimposed viral myocarditis can impact ventricular function. Treatment with inotropic agents may be indicated acutely until adequate afterload reduction can be instituted. The use of β-blocker therapy in the failure of the systemic right ventricle may be of long-term benefit by analogy to left ventricular failure, but only limited studies have been performed in this patient group. Biventricular pacing has also been used to a limited extent in congenital heart disease and systemic right ventricles and may also be of benefit in advanced cases.²² Patients with intractable cases should be considered for heart transplantation.

Another group of patients who are likely to develop heart failure are those whose anatomy falls within the broad category of single ventricles. These include the rare patients with double outlet right ventricles, double-inlet left ventricles, tricuspid atresia, and pulmonary atresia with intact ventricular septum. By adulthood, these patients have been treated with a variety of palliative procedures, in most cases to increase pulmonary blood flow most frequently through a cavopulmonary connection (i.e., Fontan or Glenn procedure), although adults are still occasionally seen with a systemic-pulmonary arterial connection (i.e., Potts or Waterston procedure). Heart failure may be an inevitable feature of the natural history of the single ventricle, but patients may present at earlier stages with failure of palliative procedure. The latter is of particular concern in patients with one of the variants of the Fontan procedure. In the previous iteration of this procedure, direct connection, usually via a conduit, between the right atrium and the pulmonary artery was established. Sluggish flow within the right atrium can lead to thrombus formation, rising pressures within the Fontan circuit and increasing coronary sinus pressures with decreased coronary perfusion pressures. The left ventricle develops diastolic dysfunction. Additionally, the enlarging right atrium may cause atrial septal shift that obstructs the flow of the right pulmonary veins leading to increases in pulmonary pressure. Fontan conversion to an extracardiac conduit may be considered for these patients. When combined with a Maze procedure, this operation may help control atrial arrhythmias. The role of this procedure, which carries considerable morbidity and mortality, is still under debate. Whether younger patients with Fontan surgery who received extracardiac conduits fare better in terms of late heart failure remains to be seen.

Other potential causes of late systolic failure include lesions which lead to chronic volume overload of the systemic ventricle. Included in this group are congenital causes of aortic and atrioventricular valve regurgitation (mitral in the systemic left ventricle and tricuspid in the systemic right ventricle), ventricular septal defect, or patent ductus arteriosus with large left to right shunts.

Abnormalities of Diastolic Function

Diastolic dysfunction as the cause of right or left ventricular failure is less common in patients with congenital heart disease than in those with acquired heart disease, but its incidence will increase as congenital patients continue to age. Symptoms of pulmonary congestion may occur in the setting of left ventricular hypertrophy and fibrosis due to long-standing left ventricular outflow tract obstruction, congenital valvular aortic stenosis, or aortic coarctation. Once obstruction is relieved, the hypertrophy regresses, but fibrosis may persist, producing late arrhythmias and even sudden death. A well-recognized consequence of impairment in left ventricular diastolic function that occurs with age is increased left-to-right shunting across an ASD. The increased shunting may contribute to the almost ubiquitous atrial arrhythmias in patients older than 60 years with ASD and ultimately right ventricular failure.

Right ventricular hypertrophy is most common in the setting of pulmonary valve stenosis. The overwhelming success of surgical and balloon valvuloplasty for this condition in childhood has generally insured normal survival in those treated. Patients with tetralogy of Fallot demonstrate left and right ventricular fibrosis by late gadolinium enhancement on MRI that correlates with ventricular dysfunction, exercise intolerance, and arrhythmia,¹⁶ and similarly increased fibrosis after atrial switch procedures correlates with aging, declining function, and clinical events.²³

Abnormalities of Valve Function

The sudden development of left-sided valvular regurgitation is most likely to present as acute heart failure. Acute aortic regurgitation associated with congenital heart disease is most likely from destruction of a bicuspid valve due to endocarditis or from dissection of the aorta in Marfan syndrome. Aortic valve endocarditis may also occur in the setting of discrete fibromuscular subaortic stenosis and may complicate a so-called supracristal (subarterial) VSD. An acute manifestation of the latter is rare.

Acute mitral regurgitation may also occur in the setting of endocarditis or as a result of chordal rupture in the presence of mitral valve prolapse. Prosthetic valve dysfunction is discussed later in this chapter.

Management

Initial management of the patient should be aimed at acute stabilization by reducing preload using diuretics and nitrates, reducing afterload using vasodilators, and providing inotropic support when necessary. However, therapies for heart failure must be tailored to the individual. For example, in patients with Eisenmenger syndrome or unrepaired tetralogy of Fallot, excessive diuresis can result in a severe fall in cardiac output, and afterload reduction with systemic vasodilators may result in worsening right-to-left shunt. Correction of inciting or aggravating conditions such as arrhythmias and fever may benefit the patient. Once the patient is acutely stabilized, further diagnostic procedures can be performed to determine definitive therapy.

Patients with outflow tract obstruction and secondary hypertrophy are highly dependent on adequate preload and, therefore, are subject to hypotension with diuresis. Thus, treatment of congestive heart failure due to diastolic dysfunction includes relief of obstruction when present, careful diuresis with avoidance of hypovolemia, and slowing of the heart rate when appropriate. For patients in atrial fibrillation, restoration of sinus rhythm may improve cardiac output.

Failed Palliative Procedures

Systemic-Pulmonary Arterial Shunts

Systemic-pulmonary shunts (Table 34-3) are employed in cyanotic patients with severely reduced pulmonary arterial blood flow, usually due to outflow obstruction. The three most commonly used shunts were the Waterston procedure, which connects the ascending aorta to the right pulmonary artery; the Potts procedure, which connects the descending aorta to the left pulmonary artery; and the Blalock-Taussig shunt, which connects the subclavian artery directly (classic) or indirectly via a Gore-Tex graft (modified) to the pulmonary artery. The Waterston and Potts procedures are no longer performed because they are associated with a high incidence of congestive heart failure and pulmonary vascular disease; however, adults with tetralogy of Fallot and pulmonary atresia who have had palliative procedures are still occasionally encountered. Congestive heart failure, endocarditis, brain abscess, and severe cyanosis due to outgrowing of the shunt or development of pulmonary vascular disease are potential sequelae in these patients.

Table 34–3 Palliative Shunts

	Anatomy	Comment
*Systemic Arterial–Pulmonary Arterial*
Classic BT	Subclavian artery to PA	Absent ipsilateral radial pulse; continuous murmur
Modified BT	Subclavian to PA conduit	Preserved pulse; continuous murmur
Central shunt	Aorta to PA conduit	Continuous murmur
Waterston	Ascending aorta to RPA	Continuous murmur^∗
Potts	Descending aorta to LPA	Continuous murmur^∗
*Systemic Venous–Pulmonary Arterial*
Glenn	Superior vena cava to PA	No murmur; arrhythmias uncommon
Fontan	Total cavopulmonary shunt	No murmur; atrial arrhythmias common
*Other*
Rastelli	Right ventricle to PA	Valve degeneration may lead to pulmonary insufficiency murmur

BT, Blalock-Taussig; LPA, left pulmonary artery; PA, pulmonary artery; RPA, right pulmonary artery.

∗ Continuous murmur may disappear in presence of pulmonary hypertension.

Patients with the classic Blalock-Taussig shunt have an absent pulse in the ipsilateral arm; in those with a modified Blalock-Taussig shunt, the pulse is preserved. A continuous murmur is a normal finding; its absence heralds obstruction of the shunt. Thus worsening cyanosis and a diminished murmur should prompt urgent catheterization and intervention. Endarteritis may also complicate this type of shunt.

Cavopulmonary Connections

Cavopulmonary connections (see Table 34-3) consist of a group of palliative procedures commonly performed in patients with tricuspid atresia and other single ventricle lesions, broadly categorized into the Glenn procedures and the Fontan procedure. In the Glenn procedure, the superior vena cava is anastomosed to the right pulmonary artery. However, in older children and adults, the blood supply from the head and neck is rarely adequate for relief of cyanosis; thus many patients proceed to a total cavopulmonary connection (i.e., Fontan procedure), which is accomplished through a variety of surgical techniques. Supplemental systemic-pulmonary arterial shunts are also used. Pulmonary blood flow is predominantly passive; thus systemic venous pressures are elevated.

The family of Fontan procedures is associated with frequent complications that include chylous pleural effusions, liver failure, protein-losing enteropathy, and pulmonary thromboembolic disease. Although they are more likely to present chronically, these complications may occasionally result in an acute decompensation, especially in patients with limited cardiopulmonary reserve and may be triggered by arrhythmia or a pulmonary thromboembolic event. In addition, increasing pleural effusions compromise respiratory status through atelectasis, exacerbating cyanosis. Ascites are a result of liver failure, and hypoalbuminemia may also reduce lung volumes by elevating the diaphragm. Thrombi arising in the deep venous system and right atrium can result in pulmonary emboli, with a rise in pulmonary artery pressures and consequent reduction in pulmonary blood flow. Acutely, TEE and catheterization with angiography may be necessary to exclude conduit obstruction and thromboembolic disease. Acute management may include thoracentesis, paracentesis, and anticoagulation or thrombolytic therapy.

Prosthetic Valve and Prosthetic Material Failure

The presentation of prosthetic valve dysfunction in adults with congenital heart disease is generally similar to that in patients who have had valve replacement for acquired heart disease; however, there are several important differences in patients who had valve replacement during childhood. First, the size of the valve may be an important factor because growth of the patient produces increased requirements for higher stroke volumes. Thus the patient with prosthetic valve mismatch may have diminished exercise tolerance and heart failure. Second, the rate of degeneration of bioprostheses or homografts is faster in young patients; the leaflet thickening and tearing may occur as early as 5 years following implantation instead of the expected 10 to 15 years in adult patients.²⁴ Third, prosthetic valves are more frequently combined with a conduit that can also become obstructed through a process known as pseudointimal thickening.

Other complications of prosthetic valves common in those with acquired and congenital valve disease include endocarditis and thrombosis; the latter is confined primarily to mechanical prostheses. Primary failure is rare in the types of mechanical valves (most frequently, St. Jude bileaflet valves) usually encountered in this population.²⁵

The clinical presentation may be that of sudden heart failure, syncope, or a cerebral, cardiac, or peripheral embolic event. Acute valve thrombosis can result in cardiopulmonary arrest. Transthoracic echocardiography may detect stenosis by identifying an increased gradient across an obstructed valve or conduit and regurgitation of a prosthetic aortic valve, but it is rarely adequate for identifying the cause of obstruction or detecting prosthetic mitral regurgitation. In these cases TEE is usually required.²⁶ Moreover, when prosthetic valve endocarditis or thrombosis is suspected, TEE is virtually mandated because of the low sensitivity of surface imaging in these entities. Degeneration of bioprosthetic leaflets and perivalvular leaks are also accurately diagnosed with TEE. Conduit obstruction is more likely to present subacutely and may require catheterization and angiography for diagnosis. The preferred treatment of an acute thrombosis of a mechanical prosthesis is surgery; if surgery is not possible, thrombolytic therapy has met with some success, albeit with a high rate of hemorrhagic complications.²⁷ The management of anticoagulation during surgery and pregnancy in patients with prosthetic valves is similar to that for those with acquired disease.

Other prosthetic materials are used for patch closures of ASDs and VSDs. Operations performed before 1970 were more prone to patch leaks. Although these persistent defects are rarely hemodynamically significant, they represent an important nidus for endocarditis at the site of the jet lesion and are a potential cause of hemolysis.

The long-term sequelae of palliative procedures most often have slow chronic deterioration of functional capacity. The less common acute presentations are potentially life-threatening and require prompt diagnosis and, frequently, emergency intervention.

Other Catastrophic Emergencies

Cerebrovascular Disease

Among the neurologic complications of congenital heart disease is subarachnoid hemorrhage as a result of rupture of an aneurysm of the circle of Willis in association with aortic coarctation. Although rupture is more common in those with unrepaired coarctation, patients with repairs remain at risk, especially in the presence of persistent hypertension. Patients with coarctation of the aorta are also at increased risk of thrombotic strokes as a result of long-standing hypertension.

Additional neurologic complications of congenital heart disease include brain abscesses and embolic stroke in the presence of right-to-left shunt. Brain abscesses may have new onset of seizures, headache, or unexplained fever. The diagnosis can be made by computed tomography scanning or magnetic resonance imaging. In young patients with acute cerebral ischemia, an intracardiac communication responsible for right-to-left shunting should be suspected. Many patients have been shown to have a patent foramen ovale by transthoracic echocardiography or TEE. An ASD may also have a cerebral ischemic stroke.

Thrombotic strokes are rare in patients with cyanotic heart disease and secondary erythrocytosis.²⁸ Prophylactic phlebotomy is not indicated in the asymptomatic patient with an elevated hematocrit; however, the patient with decompensated erythrocytosis, defined as an increasing hematocrit or iron deficiency,²⁹ may have headaches, lethargy and, less frequently, seizures. These patients can benefit from iron replacement in the event of iron-deficiency states and phlebotomy in the event of extreme polycythemia. A reasonable target for phlebotomy is a hematocrit of less than 60%, which should be achieved gradually by serial phlebotomy with volume replacement.

Pulmonary Hemorrhage

Pulmonary hemorrhage can occur in patients with Eisenmenger syndrome as a result of pulmonary infarction and pulmonary arteriolar rupture. These life-threatening events may complicate pregnancy and are potentially fatal; however, the differential diagnosis of hemoptysis includes pulmonary edema, which may respond to diuretic therapy, and pulmonary infections.³⁰ When chest radiography is nondiagnostic, bronchoscopy may be required.

Pulmonary artery hemorrhage more commonly complicates right heart catheterization with a flow-directed balloon-tipped catheter, in particular in the presence of severe pulmonary vascular disease. When it is necessary to perform invasive monitoring, care should be taken not to inflate the balloon in a small pulmonary branch artery but rather to inflate it in a larger branch, then float it out to a smaller branch to obtain the pulmonary capillary wedge pressure.

Control of hemoptysis may be thwarted by the bleeding diathesis that accompanies the polycythemia of cyanotic heart disease. These management issues are beyond the scope of this chapter.

Eisenmenger Syndrome

In Eisenmenger syndrome, irreversible pulmonary vascular disease develops in response to left-to-right shunt (e.g., VSD, ASD, PDA).³¹ There is consequent reversal of shunt flow to right-to-left and cyanosis. The oxygen saturation is markedly decreased, and polycythemia is present. There is ECG and radiographic evidence of right ventricular hypertrophy. These patients have tenuous hemodynamics and are susceptible to severe hypotension in the setting of dehydration or hypovolemia from many causes, including diuretic treatment. Because of the fixed pulmonary vascular resistance, there is limited ability to increase cardiac output. Systemic vasodilators are contraindicated because they may result in hypotension and worsening cyanosis with increased right-to-left shunting. Pregnancy is poorly tolerated; a high fetal and maternal mortality is associated with Eisenmenger syndrome.³² Pulmonary thrombosis, hemorrhage, or both may complicate pregnancy. Endocarditis and arrhythmias are common (discussed previously). Also as mentioned previously, brain abscess may occur in this setting.