Summary
Highlights
Congenital heart disease refers to structural abnormalities of the heart present at birth, making them the most common birth defects. They are categorized into three types: left-to-right shunting (acyanotic), right-to-left shunting (cyanotic), and obstructive defects. Blood typically flows from high pressure (left side) to lower pressure (right side). Left-to-right shunts increase pulmonary blood flow, leading to pulmonary hypertension and potentially Eisenmenger syndrome, where the shunt reverses direction, causing cyanosis due to deoxygenated blood entering systemic circulation.
VSD, accounting for 20% of CHD, is a hole in the ventricular septum. Its types include outlet, inlet, perimembranous, and muscular VSDs. Small VSDs are often asymptomatic, while larger ones cause symptoms like dyspnea, tachycardia, poor feeding, growth issues, pallor, and recurrent respiratory infections. Diagnosis is via physical exam (pan-systolic murmur), echo, chest X-ray (cardiomegaly), and ECG (ventricular hypertrophy). Treatment varies from no closure for small defects to diuretics, feeding support, and surgical or transcatheter closure for larger ones.
ASD, comprising 10% of CHD and more common in females, is a hole in the atrial septum. Types include sinus venosus, ostium primum, ostium secundum, and unroofed coronary sinus. Small ASDs are often asymptomatic until adulthood, presenting with dyspnea on exertion and arrhythmias. Larger ones can lead to heart failure, failure to thrive, and recurrent lung infections. Physical exam reveals a systolic murmur and fixed splitting of S2. Echocardiography is definitive. Some ASDs close spontaneously, others require percutaneous or surgical closure. A key risk in septal defects is paradoxical embolism.
The ductus arteriosus is a normal fetal connection between the pulmonary artery and aorta. Post-birth, it typically closes within 2-3 weeks. A PDA is when it fails to close, more common in prematurity, accounting for 9-12% of CHD. It causes blood to shunt from the aorta to the pulmonary artery, leading to pulmonary hypertension and right heart strain. Cyanosis affects the lower half of the body. Symptoms include poor growth, recurrent infections, and dyspnea. A continuous 'machinery' murmur is characteristic. Prostaglandins keep it open, so NSAIDs (ibuprofen, indomethacin) can aid closure, while severe cases require surgery or coiling.
Normally, pulmonary veins connect to the left atrium. In TAPVC, they connect to the right atrium or systemic veins. Partial forms (one or more veins abnormal) might be asymptomatic, while total forms (all veins abnormal) are incompatible with life without an ASD, as oxygenated blood cannot reach the systemic circulation. This rare defect (less than 1% of CHD) can present as respiratory distress if pulmonary veins are obstructed. Diagnosis can be challenging via echo, often requiring CT or MRI. Surgical correction is necessary for right-sided volume overload.
TOF makes up 4-8% of CHD and involves four abnormalities: VSD, pulmonary stenosis (right ventricular outflow tract obstruction), right ventricular hypertrophy, and an overriding aorta. Symptoms include progressive cyanosis, exertional dyspnea, poor growth, and erythrocytosis. 'Tet spells' are acute cyanotic episodes, often triggered by exertion. Squatting in older children helps increase systemic vascular resistance. A systolic murmur is heard. Chest X-ray shows a 'boot-shaped heart.' Prostaglandins can maintain PDA to increase pulmonary blood flow in severe cases, but surgical repair is definitive.
TGA, 4% of CHD, involves the aorta arising from the right ventricle and the pulmonary artery from the left, creating two separate circulations. This is life-threatening without a connection like an ASD, VSD, or PDA. Cyanosis appears in the first hours of life, requiring emergency intervention. Physical exam may be unremarkable apart from cyanosis. Chest X-ray might show an 'egg on a string' appearance, but echo confirms diagnosis. Prostaglandin E1 is used to maintain PDA, followed by an atrial switch surgery, typically within the first weeks of life.
Ebstein's anomaly is a rare malformation of the tricuspid valve, leading to severe regurgitation and often an associated ASD. The tricuspid valve is displaced lower than usual, enlarging the right atrium and reducing the right ventricle's size. It's linked to maternal lithium use. Presentation varies from asymptomatic to heart failure, cyanosis, or poor growth in newborns, and dyspnea or atrial arrhythmias in adults. A split S1, systolic murmur, and a galloping rhythm are common. Chest X-ray shows cardiomegaly and ECG may show tall P waves or WPW. Prostaglandin E1 can keep PDA open, but surgery is the definitive treatment.
Aortic coarctation, 5% of CHD, is a narrowing of the aortic arch, often near the ductus arteriosus. 70% of patients also have a bicuspid aortic valve, and it's associated with Turner syndrome. The narrowing causes decreased blood flow/pressure distal to the coarctation and increased pressure proximally. Taking blood pressure in all four limbs helps locate the narrowing. Mild cases may manifest as hypertension in adulthood. Severe cases rely on the PDA for distal blood flow; its closure leads to shock and metabolic acidosis. A murmur in the left infraclavicular region may be heard, and CT is used for diagnosis. Treatment involves medical management (beta-blockers) or surgical correction and balloon dilation.