Ventricular Septal Defect
Definition
VSD is an opening in the ventricular septum that separates the right and the left ventricles. There are four types of ventricular septal defects.
Type I (5%) - known as supracristae defect, located above supraventricularis, just under the annulus of aorta.
Type II (80%) - known as infracristal defects, located low in the membraneous septum beneath the supraventricularis.
Type III (11%) - known as the canal-type, may accompany complete AV canal.
Type IV (4%) - results from the excessive resorption of septal tissue during the muscular septal formation.
Pathology
Left to right shunting, pulmonary hypertension, and heart failure due to volume overload.
Clinical Manifestations
May occur as an isolated defect or in combination with other anomalies. Incidence in the same in males and females. Blood is shunted into the lungs causing left ventricular pressure to be higher than right ventricular pressure and right ventricular outflow tract resistance offers less impedence to flow than that of systemic circulation. Larger VSD would result in less resistance and the greater flow across it from high pressure LV to low pressure RV.
Surgical Interventions
Operations can be performed through right atrium, right ventricle, left ventricle or aorta. RA approach is usually through the tricuspid valve and is commonly used for membraneous defects. Supracristal lesions require a right ventriculotomy and muscular defects often are corrected through left apical venticulotomy. When aortic regurgitation is associated to a vsd, the defect can be closed through the aortic valve.
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