Cardiology · Congenital Heart Disease
The facts most likely to be tested
Ventricular septal defect is the most common congenital heart defect in children.
The classic physical exam finding is a harsh, holosystolic murmur heard best at the left lower sternal border.
Small defects are often asymptomatic and may close spontaneously, while large defects lead to left-to-right shunting and congestive heart failure symptoms.
Large, uncorrected defects can lead to Eisenmenger syndrome, characterized by pulmonary hypertension and cyanosis due to shunt reversal.
Echocardiography is the diagnostic test of choice to confirm the location and size of the defect.
Infants with large defects often present with failure to thrive, diaphoresis with feeding, and tachypnea.
Surgical closure is indicated for patients with significant left-to-right shunting, pulmonary overcirculation, or failure to thrive.
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A 3-month-old male is brought to the clinic by his mother due to poor weight gain and excessive sweating during feedings. On physical examination, the infant is in the 10th percentile for weight. Cardiac auscultation reveals a harsh, holosystolic murmur at the left lower sternal border accompanied by a palpable thrill. The lungs are clear to auscultation, but the infant exhibits mild tachypnea at rest. The remainder of the physical exam is unremarkable.
What is the most likely diagnosis?
Ventricular septal defect
The clinical presentation of a holosystolic murmur at the left lower sternal border combined with signs of heart failure (diaphoresis with feeding, failure to thrive) is classic for a significant ventricular septal defect.
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Etiology / Epidemiology
Most common congenital heart defect; often associated with fetal alcohol syndrome or Down syndrome.
Clinical Manifestations
Classic holosystolic murmur at the left lower sternal border; intensity inversely proportional to size.
Diagnosis
Echocardiogram is the gold standard; confirms location and shunt size.
Treatment
Small defects often close spontaneously; diuretics and ACE inhibitors for heart failure symptoms.
Prognosis
Risk of Eisenmenger syndrome if left untreated; monitor for pulmonary hypertension.
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Epidemiology & Etiology
VSD is the most common congenital heart defect, accounting for approximately 20-30% of all cases. It is frequently seen in patients with trisomy 21, trisomy 18, and trisomy 13. Maternal exposure to rubella or alcohol increases risk.
Pertinent Anatomy
The most common type is the perimembranous VSD, located near the aortic valve. Muscular VSDs are often multiple and located in the apical septum. Supracristal defects are associated with aortic valve regurgitation.
Pathophysiology
Left-to-right shunting occurs due to higher pressure in the left ventricle. Large shunts lead to pulmonary overcirculation, resulting in increased pulmonary vascular resistance. Chronic volume overload causes left atrial and left ventricular dilation.
Clinical Manifestations
Patients present with a harsh, high-pitched holosystolic murmur at the left lower sternal border. Large defects may cause failure to thrive, diaphoresis with feeding, and tachypnea. A mid-diastolic rumble at the apex suggests a large shunt causing mitral valve flow increase.
Diagnosis
The Echocardiogram is the diagnostic gold standard to visualize the defect and assess shunt direction. An ECG may show left ventricular hypertrophy in moderate-to-large shunts. A CXR typically reveals cardiomegaly and increased pulmonary vascular markings.
Treatment
Small, asymptomatic defects require only observation and endocarditis prophylaxis is no longer routinely recommended. Symptomatic infants are managed with diuretics (furosemide) and ACE inhibitors to reduce afterload. Surgical closure is indicated for large defects with persistent heart failure or significant pulmonary hypertension.
Prognosis
Most small VSDs close spontaneously by age 2. Failure to repair large defects leads to irreversible pulmonary hypertension and Eisenmenger syndrome, characterized by shunt reversal and cyanosis. Long-term follow-up is required to monitor for aortic regurgitation.
Differential Diagnosis
Tricuspid regurgitation: murmur increases with inspiration
Mitral regurgitation: murmur radiates to the axilla
Atrial septal defect: fixed split S2
Patent ductus arteriosus: continuous machine-like murmur
Hypertrophic cardiomyopathy: murmur intensity changes with Valsalva