CHAPTER 34 Hemodynamically Unstable Presentations of Congenital Heart Disease in Adults
AMONG THE large number of patients with cardiac emergencies, the patient with congenital heart disease is a rarity. However, with growing numbers of patients with complicated congenital cardiac lesions surviving childhood and with larger numbers with serious, but more common lesions palliated by surgery, the cardiologist increasingly is seeing more patients with congenital heart disease, some of whom will have cardiac emergencies. Between 1985 and 2000, the number of adults with congenital heart disease has doubled, resulting in approximately 1 million adult survivors in the United States who are increasingly having late complications.1 Although the anatomy and nomenclature of congenital heart disease is often intimidating to an adult cardiologist, the care in most cases is analogous to that of other adult patients. For example, the care of a young adult with heart failure from a failing systemic right ventricle is modeled after the deep clinical experience caring for patients with left heart failure. Being aware of congenital anatomy and the complications that are frequently seen in common congenital lesions, however, is important to help focus on the likely diagnosis and optimal treatment plan.
In general, patients with congenital heart disease are seen as adults because they have one or more of the following conditions2:
Native lesions in this category include:
Repaired conditions in this category include:
The majority of these lesions never present as cardiac emergencies. However, with incisions in the atrium affecting the pacemaker or conduction system; with incisions in the ventricle forming fibrous scars as the basis for re-entrant ventricular arrhythmias, with anatomic right ventricles functioning as a systemic ventricle; and with residual lesions forming the substrate for developing infective endocarditis, cardiac emergencies do occur and form the content of this chapter (Table 34-1).
Table 34–1 Cardiac Emergencies
| Life-Threatening∗ | Not Life-Threatening | |
|---|---|---|
| Arrhythmia | ||
| Ischemia | Ongoing chest pain with ischemic ECG changes | Chronic nonischemic chest pain |
| Ventricular failure | ||
| Cyanosis | Chronic cyanosis | |
| Noncardiac |
Abbreviations: AF, atrial fibrillation; BT, Blalock-Taussig shunt; CHB, complete heart block; VT, ventricular tachyarrhythmias.
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 | |
| Fontan | |
| D-transposition of great arteries | |
| L-transposition of great arteries | |
| Coarctation | |
| Left-to-right shunt | |
| Right-to-left shunt (cyanotic) | |
| Marfan |
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
Arrhythmias
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
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.
