ventricular septal defect

Ventricular septal defects (VSD) represent defects in the interventricular septum that allow a hemodynamic communication between the right and left ventricles. It typically results in a left-to-right shunt.


They represent one of the most common congenital cardiac anomalies and may be associated with up to 40% of such anomalies . They are considered the most common congenital cardiac abnormality diagnosed in children and the second most common diagnosis in adults. The estimated incidence is at ~1 in 400 births .

Clinical presentation

Clinical presentation varies depending on the size and resultant severity of the VSD . Small lesions with minimal shunting may be asymptomatic, however may have a loud harsh pansystolic murmur heard on precordial auscultation over the left sternal border . Larger lesions, in comparison, may cause signs of heart failure such as exertional dyspnea, raised jugular venous pressure, hepatomegaly, peripheral edema, or failure to thrive in pediatric patients, but may have a very soft murmur .

In addition to a pansystolic murmur, there may also be a mid/end-diastolic murmur mimicking mitral stenosis as well as an ejection systolic murmur mimicking aortic stenosis, each due to increased pulmonary circulation compared to systemic circulation resulting in more total blood passing through the left atrium and ventricle . Cyanosis is generally not seen in patients with VSDs (unless Eisenmenger syndrome develops).


While small VSDs will remain electrocardiographically occult, larger defects will classically demonstrate some of the following features :


Classification according to location
  • membranous/perimembranous (most common: 80-90%)
  • inlet/inflow
  • outlet/subarterial
  • muscular/trabecular

A VSD can occur on its own but frequently tends to occur with other cardiovascular associations:

Radiographic features

Plain radiograph

The chest radiograph can be normal with a small VSD. Larger VSDs may show cardiomegaly (particularly left atrial enlargement although the right and left ventricle can also be enlarged). A large VSD may also show features of pulmonary arterial hypertensionpulmonary edema, pleural effusion, and increased pulmonary vascular markings.

Ultrasound: echocardiography

Allows direct visualization of the septal defect; a transthoracic parasternal short axis at the level of the aortic valve is typically the view of choice for differentiation between supracristal and perimembranous defects, whereas apical and subcostal windows are preferred for muscular defects .

Specific features sought after include:

  • defect localization
    • a perimembranous VSD can be seen as a septal dropout in the area adjacent to the tricuspid septal leaflet and below the right border of the aortic annulus
    • muscular VSDs are variably located along the septum
      • may be numerous
    • inlet VSDs involve the septal component of the right ventricular inflow tract
    • supracristal VSDs are visualized as dropout above the crista supraventricularis in the right ventricular outflow tract
  • direction of VSD jet
    • a parasternal short axis at the aortic valve level will reveal aliased flow at the 10 o'clock position in a perimembranous defect
    • a supracristal VSD will demonstrate flow at the 2 o'clock position
  • hemodynamic consequences
    • restrictive VSD's have a more benign prognosis
      • tend to be smaller defects with a large attendant pressure gradient 
      • rarely progress to cause structural or hemodynamic derangement
    • non-restrictive septal defects are larger and tend to transmit significant volume to the right-sided circulation
      • demonstrate low-velocity jets with a much lower pressure gradient
      • associated with dilation of the left ventricle and pulmonary hypertension
        • the pulmonary artery systolic pressure (sPAP) may be calculated using the doppler acquired velocity across the defect and the systolic blood pressure
          • sPAP = SBP - 4(jet velocity)^2

CTA with ECG-gating allows direct visualization of the defect. Large VSD's may be seen on non-gated studies.


May also show added functional information (e.g. quantification/shunt severity) in addition to anatomy. Some muscular defects can give a "Swiss cheese" appearance owing to their complexity.

Treatment and prognosis

The prognosis is good for small VSDs which show a high spontaneous intrauterine or postnatal closure rate. VSDs usually do not cause any hemodynamic compromise in utero due to the right and left ventricular pressures being very similar during that period.

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