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For further information, see CMDT Part 10-07: 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


  • 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


  • 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 ...

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