Ventricular Septal Defect

Key Features

• Four types are often described

  • Type A: Ventricular septal defect (VSD) lies underneath the semilunar valves

  • Type B: The membranous VSD with three variations

  • Type C: The inlet VSD that is present below the tricuspid valve and often part of the AV canal defect

  • Type D: The muscular VSD

• VSD sizes are defined by comparison to the aortic root size

  • Small or restrictive VSD diameter is < 25% of the aortic root diameter

  • Moderately restrictive VSD diameter is 25–75% of the aorta

  • Unrestricted VSD size is > 75% of the aortic diameter

  • The size can also be quantitated based on the Qp/Qs (left-to-right shunt)

    • Restrictive lesion: < 1.5:1

    • Moderately restrictive lesion: 1.5–2.2:1

    • Unrestricted lesion: > 2.2:1

  • Membranous and muscular septal defects may spontaneously close in childhood as the septum grows and hypertrophies

  • A left-to-right shunt is present, the degree of which depends on associated systolic RV pressure

  • Presentation in adults depends on size of left-to-right shunt and presence or absence of associated pulmonic or subpulmonic stenosis

  • Large shunts with unprotected lungs invariably lead to pulmonary vascular disease and severe pulmonary hypertension (Eisenmenger physiology)

  • Small defects may be asymptomatic

Clinical Findings

• The smaller the defect, the greater the gradient from the left to the right ventricle and the louder the murmur

• Small shunts: loud, harsh holosystolic murmur in third and fourth left interspaces along the sternum and, occasionally, mid-diastolic flow murmur

• Systolic thrill common

• Large shunts: right ventricular volume and pressure overload may cause pulmonary hypertension and cyanosis

Diagnosis

• ECG

  • May be normal

  • May show left, right, or biventricular hypertrophy

• Chest radiograph

  • Increased pulmonary vascularity

  • Enlarged pulmonary artery, left ventricle, and left atrium

• Doppler echocardiography

  • Diagnostic

  • Can assess magnitude and location of shunt and estimate gradient across the VSD

  • Can also estimate pulmonary artery pressure and address associated lesions

• Cardiac CT and MRI can visualize defect and other anatomic abnormalities

• Cardiac catheterization

  • Usually reserved for those with at least moderate shunting

  • Can quantitate pulmonary vascular resistance and degree of pulmonary hypertension

Treatment

• Antibiotic prophylaxis recommended for dental work when:

  • VSD is residual from a prior patch closure

  • Associated pulmonary hypertension and cyanosis is present

• Small shunts do not require closure in asymptomatic patients

• Large shunts should be surgically or percutaneously repaired

• Surgical mortality is 2–3%, but ≥ 50% if pulmonary hypertension is present

• Surgery is contraindicated in Eisenmenger syndrome

• Percutaneous closure devices are available and effective in some situations

• 2018 AHA/ACC Adult Congenital Heart Disease Guidelines

  • Indication for VSD closure: At least a 1.5:1 left-to-right shunt, PVR is less than one-third that of the SVR, and the PA systolic pressure is more than one-half of the aortic systolic, then the risk of VSD closure despite some pulmonary hypertension is acceptable

  • Contraindication for VSD closure: If the ...