Ventricular Septal Defect (VSD)

Key Features

Essentials of Diagnosis

• Holosystolic murmur at lower left sternal border with right ventricular (RV) heave

• Presentation and course depend on size of defect and the pulmonary vascular resistance (PVR)

• Failure to thrive, tachypnea, and diaphoresis with eating

• Left-to-right shunt with normal PVR

• Large defects may cause Eisenmenger syndrome if not repaired early

General Considerations

• Accounts for about 30% of all congenital heart disease

• Defects in the ventricular septum occur both in the membranous portion of the septum (most common) and the muscular portion.

• VSDs follow one of four courses

  • Small, hemodynamically insignificant VSDs (< 3 mm in diameter)

    • Between 80% and 85% of VSDs are small at birth and will close spontaneously

    • In general, small defects in the muscular interventricular septum close sooner than those in the membranous septum

    • In most cases, a small VSD never requires surgical closure

    • Fifty percent of small VSDs will close by age 2 years, and 90% by age 6 years, with most of the remaining closing during the school years

  • Moderate VSDs (3–5 mm in diameter)

    • Asymptomatic patients with moderate-sized VSDs account for 3–5% of children with VSDs

    • If the patient is asymptomatic and without evidence of pulmonary hypertension, these defects can be monitored serially as some close spontaneously over time

  • Large VSDs with normal PVR (usually 6–10 mm in diameter)

    • Often require surgery; timing depends on the clinical situation

    • Surgery before age 2 years in patients with large VSDs essentially eliminates the risk of pulmonary vascular disease

  • Large VSDs with pulmonary vascular obstructive disease

    • Most patients with inoperable pulmonary hypertension the condition develops progressively

    • The combined data of the multicenter National History Study indicate that almost all cases of irreversible pulmonary hypertension can be prevented by surgical repair of a large VSD before age 2 years

Clinical Findings

• Patients with small or moderate left-to-right shunts usually have no cardiovascular symptoms

• Patients with large left-to-right shunts are usually ill early in infancy

• These infants have frequent respiratory infections and gain weight slowly

• Dyspnea, diaphoresis, and fatigue can develop as early as 1–6 months of age

• Older children may experience exercise intolerance

• In children and adolescents with persistent large left-to-right shunt, the pulmonary vascular bed undergoes structural changes, leading to increased PVR and reversal of the shunt from left-to-right to right-to-left (Eisenmenger syndrome)

• Cyanosis will then be present

Small left-to-right shunt

• No lifts, heaves, or thrills

• The first sound at the apex is normal, and the second sound at the pulmonary area is split physiologically

• A grade II–IV/VI, medium- to high-pitched, harsh pansystolic murmur is heard best at the left sternal border in the third and fourth intercostal spaces

• Murmur radiates over the entire precordium

• No diastolic murmurs are heard

Moderate left-to-right shunt

• Slight prominence of the precordium ...