1. b. The heart develops from a single tube and is first recognizable at 15 days of gestation. Congenital heart diseases have an incidence of 6 per 1,000 live births. Chamber septal defects are the most common congenital heart anomaly.

2. d. Trisomy 21 is the most common cytogenetic abnormality and is specifically associated with complete atrioventricular canal defect and left ventricular outflow obstruction. Turner syndrome (45XO) is commonly associated with bicuspid aortic valve and coarctation of the aorta and DiGeorge syndrome (deletions in chromosomal region 22q11.2) is associated with persistent truncus arteriosus.

3. a. Mitral valve prolapse occurs in 1% to 3% of the population and is most commonly seen in Marfan syndrome. Other common valvular disease includes congenital aortic valve disease, which commonly presents at 50 to 70 years of age and manifests as stenosis in most cases.

4. d. Conotruncal malformations, commonly associated with velocardiofacial syndrome (deletions in 22q11), include persistent truncus arteriosus, absent ductus arteriosus, interrupted aortic arch, tetralogy of Fallot, and right-sided aortic arch. Coarctation of the aorta is less common. Patent ductus arteriosus, on the other hand, is commonly associated with trisomy 21 and congenital rubella infection.

5. c. This is the typical scenario of complete transposition: the aorta ascends parallel and to the right of the pulmonary artery. There is AV concordance because the right atrium communicates with the right ventricle from which the aorta arises and the left atrium is in continuity with the left ventricle from which the pulmonary artery arises.

6. d. The image shows “Quilty lesion,” which is a dense endocardial collection of lymphocytes. This phenomenon is seen in heart-transplant patients receiving cyclosporine therapy and is not related to rejection.

7. b. Carcinoma of the lung is the most frequent metastatic tumor to heart, followed by lymphoma, breast carcinoma, and other tumors.

8. a. Congenital heart defects result from rubella infection in the first 3 months of gestation. The most common anatomic defects include patent ductus arteriosus, pulmonary artery stenosis, and systemic arterial hypoplasia.

9. c. Brown-Brenn stain is a modified Gram stain for bacteria. This stain is indicated in cases of infective endocarditis endocardial vegetations.

10. a. Cardiac myxoma is the most common primary tumor of the heart and constitutes 50% to 80% of primary heart tumors. It is most commonly located in the atrium and characteristically presents as a heart murmur that changes with time and position.

11. a. The most common artificial heart valves are bioprosthetic valves. The remaining choices are examples of mechanical valves.

12. b. Cardiomyopathy related to Adriamycin is characterized by myofibrillar loss and vacuolar degeneration of heart myocytes. Electron microscopy reveals distension and swelling of the endoplasmic reticulum. Inflammation is notably minimal to absent.