Pathophysiology, Clinical Recognition, and Treatment of Congenital Heart Disease

Atrial level communications include any of the following: (1) ostium secundum atrial septal defect (ASD), (2) ostium primum atrial septal defect, (3) sinus venosus atrial septal defect, and (4) coronary sinus atrial septal defect. The common ASD among these are the ostium secundum ASD representing approximately 70% of all ASDs. With all of the ASDs, significant pulmonary hypertension rarely occurs before the third to fourth decade. Fifty percent or more of ventricular septal defects (VSDs) close spontaneously in early childhood, even as late as adolescence. The VSDs with large left-to-right shunts may lead to severe pulmonary hypertension with bidirectional or right-to-left shunting and cyanosis in the adult. Patent ductus arteriosus leads to a continuous systolic diastolic murmur under the left clavicle and places the patient at risk for infection at the ductus site, and when it leads to a large left-to-right shunt, may cause severe pulmonary hypertension. Aortic valve stenosis in the child and early in adulthood is usually caused by a bicuspid or a unicuspid valve. Supravalvular aortic stenosis occurs in two settings. Williams syndrome is a dysmorphic syndrome caused by a mutation of the elastin gene or chromosome 7, often associated with hypercalcemia in infancy. The second group of patients with supravalvular aortic stenosis have a familial form without hypercalcemia, dysmorphic features, or behavioral abnormalities. Subvalvular aortic stenosis has three types: membranous subaortic stenosis, a fibromuscular tunnel type, and an idiopathic hypertrophic subaortic stenosis type. Pulmonary stenosis may be valvular, supravalvular, or subvalvular. Congenital mitral stenosis in adults is uncommon. Shone syndrome describes the occurrence of multiple levels of obstruction to blood flow into and out of the left ventricle and in the aorta. The classic picture includes mitral stenosis with a parachute mitral valve (single papillary muscle), subaortic stenosis, a bicuspid aortic valve, and coarctation of the aorta. Tricuspid stenosis is generally acquired rather than congenital and causes include rheumatic heart disease, carcinoid syndrome, and right atrial myxoma. Ebstein’s anomaly consists of downward displacement of the tricuspid valve “atrializing” the inflow tract of the right ventricle. Tricuspid insufficiency, right-to-left shunts at the atrial level, and supraventricular arrhythmias often coexist. Coarctation of the aorta as manifested in the adult is almost always at or just distal to the ligamentum arteriosum and the take-off of the left subclavian artery. This often leads to hypertension in the arms and reduced pressures and pulses in the lower extremities sometimes with some growth retardation in the legs. Tetralogy of Fallot consists of a large VSD, pulmonary stenosis, either valvular or infundibular or both, right ventricular hypertrophy, and overriding of the ventricular septum by a dilated aorta. Transposition of the great arteries in the adult exists as D-transposition, L-transposition, and double-outlet RV. Truncus arteriosus exists as three types. Type I has a common trunk, but this gives rise to separate ascending aorta and pulmonary trunk. In type II, the truncus extends up to the right and left pulmonary artery bifurcations. In type III, there is no separate pulmonary trunk.