During a routine athletic physical, a 15-year-old boy is found to have a systolic thrill that is palpable at the lower left sternal border accompanied by a harsh, pansystolic murmur that is heard best at the site of the thrill. He is asymptomatic and has no evidence of hypertension, cyanosis, or edema. An electrocardiogram and a chest radiograph are normal.

Questions

What is the most likely diagnosis?

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What is the natural history of this condition?

What are potential sequelae if this condition remains untreated?

Answers to Case 29: Ventricular Septal Defect

Summary: During a routine physical, a 15-year-old boy is found to have a systolic thrill at the lower left sternal border with a harsh, pansystolic murmur heard best at the site of the thrill. An electrocardiogram and a chest radiograph are normal.

  • Most likely diagnosis: Ventricular septal defect (VSD).

  • Natural history: Some VSDs, if small, may close spontaneously. Larger ones require surgical repair.

  • Unrepaired VSDs: Heart failure with pulmonary hypertension may result. Poor growth and, in young children, poor brain development may ensue. Patients are also susceptible to infected clots and pulmonary infections.

Clinical Correlation

Ventricular septal defects are the most common congenital heart defects; they affect approximately 5 per 1000 live births and represent approximately 30 percent of all congenital heart defects. In approximately 25 percent of patients, there are coexisting extracardiac anomalies. Congenital heart defects can be detected in stillbirths up to 10 times more frequently than in live births. Girls more frequently present with atrial septal defects and patent ductus arteriosus. In contrast, most left-sided obstructions, such as complete transposition of great arteries, aortic coarctation, aortic stenosis, and atresia, are present in boys.

VSD results from abnormal growth and fusion of the ventricular septal system. The majority of VSDs involve defects of the membranous septum, with fewer involving outlet and inlet defects. The defects are dynamic, and 50 percent close within 2 years. Usually smaller defects close spontaneously. VSDs allow shunting of blood from the high-pressure left ventricle to the low-pressure right ventricle (see Figure 29-1). This is not evident until after delivery, after which there is a rise in the left ventricular pressure compared with the right. The resultant shunting of blood from left to right can lead to increased blood flow to the lungs and pulmonary vascular changes, pulmonary hypertension, and heart failure.

FIGURE 29–1.

Schematic representation of a normal heart and a heart with ventricular septal defect.

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