The correct answer is D. This boy has a congenital heart defect known as tetralogy of Fallot. Tetralogy of Fallot is defined as pulmonary stenosis, ventricular septal defect, dextroposition of the aorta (overriding), and right ventricular hypertrophy. It is the most common type of cyanotic congenital heart disease. Symptoms depend on the size of the ventricular septal defect and the degree of the right ventricular outflow tract obstruction. Acyanotic (pink) tetralogy occurs when there is sufficient pulmonary blood flow caused by mild obstruction and the shunting across the ventricular septal defect is balanced. Typically, however, patients present with cyanosis, delayed growth and development, and dyspnea. Paroxysmal hypercyanotic attacks (hypoxic, blue, or tet spells) manifest with episodes of restlessness, cyanosis, and gasping respirations. Clubbing of the fingers and toes occurs secondary to chronic hypoxia. A loud, harsh, systolic ejection murmur is heard. S2 is single or very soft because of the pulmonary stenosis. Chest radiographs reveal a boot-shaped heart (coeur en sabot) with uptilted apex. Lung fields are clear, reflecting decreased pulmonary blood flow. Electrocardiography shows right ventricular hypertrophy and right-axis deviation. An echocardiogram reveals the anatomic abnormalities. Medical management includes maintaining the ductus open in severe right-sided obstructive lesions, but surgical correction is the definitive treatment. Blue spells are treated by placing the child in knee-chest position, sedation, oxygen, and avoiding acidosis. Beta blockade with propranolol, maintaining appropriate fluid status, and maintaining the hematocrit at 55 to 65% are also helpful. Complications have become less frequent as the surgical correction is typically performed early. Cerebral thrombosis occurs with extreme polycythemia and dehydration. Patients are usually younger than 2 years of age. Brain abscess, although less common than thrombosis, is more often seen in patients older than 2 years of age. Tet patients are at higher risk for bacterial endocarditis.
Endocardial cushion defect (choice A) occurs when an atrial septal defect and ventricular septal defect are present and contiguous, and the atrioventricular valves are also abnormal. Patients who have a large atrial septal defect tend to have heart failure early in infancy, with hepatomegaly and failure to thrive. Increased pulmonary blood flow over time leads to pulmonary vascular disease and Eisenmenger physiology. A low-pitched diastolic murmur may be present and the first heart sound is accentuated. Chest radiographs show a markedly enlarged heart, reflecting enlargement of all chambers.
Myocarditis (choice B) is an inflammation of the myocardium most commonly caused by adenovirus and Coxsackie B. Connective tissue diseases, granulomatous diseases, and toxins may cause noninfectious myocarditis. The most common clinical presentation is heart failure. Arrhythmias and sudden death are less common. Patients with viral myocarditis usually have a preceding viral illness. In these cases, the patient may present with fever, signs and symptoms of heart failure, respiratory distress, and cyanosis. The erythrocyte sedimentation rate, creatine kinase, and c-reactive protein may all be elevated. Chest radiography shows an enlarged heart and pulmonary edema.
Patent ductus arteriosus (choice C) results from failure of closure of the ductus arteriosus postnatally. This results in blood flowing from the aorta to the pulmonary artery. A small patent ductus arteriosus presents with no symptoms. Large patent ductus arteriosus can cause heart failure similar to large ventricular septal defects. An apical heave may be observed, in addition to a thrill at the second left intercostal space. The characteristic murmur is described as machinery or to-and-fro murmur heard in systole and diastole. Chest radiographs show a prominent pulmonary artery and increased pulmonary vascular markings.
Transposition of the great vessels (choice E) occurs when the aorta arises from the right ventricle and the pulmonary artery from the left ventricle, resulting in a parallel circulation. It is the most common congenital heart disease to present with cyanosis in the first 24 hours of life. Cyanosis and symptoms of heart failure begin within hours to days after birth. The second heart sound may be single and loud. A murmur may or may not be present. Chest roentgenograms demonstrate increased pulmonary blood flow as the pulmonary vascular resistance decreases.
