Auscultation is generally considered sufficient for detecting a significant VSD. The murmur depends on the abnormal flow of blood from the left ventricle, through the VSD, to the right ventricle. If there is not much difference in pressure between the left and right ventricles, then the flow of blood through the VSD will not be very great and the VSD may be silent. This situation occurs a) in the fetus (when the right and left ventricular pressures are essentially equal), b) for a short time after birth (before the right ventricular pressure has decreased), and c) as a late complication of unrepaired VSD. Confirmation of cardiac auscultation can be obtained by non-invasive cardiac ultrasound (echocardiography). To more accurately measure ventricular pressures, cardiac catheterization, can be performed. Classification
Although there are several classifications for VSD, the most accepted and unified classification is that of Congenital Heart Surgery Nomenclature and Database Project. The classification is based on the location of the VSD on the right ventricular surface of the inter ventricular septum and is as follows:

Multiple
Type 1
Type 1 is sub aortic

Type 2
Type 2 also known as perimembranous, paramembranous, conoventricular, membranous septal defect, and subaortic. Most common variety found in 70%

Type 3
Type 3 also known as inlet (or AV canal type). Commonly associated with atrioventricular septal defect, found in about 5%

Type 4
Type 4 also known as muscular (trabecular)

Located in the muscular septum, found in 20%.
These findings include a "corkscrew" appearance of arteries that result from vascular damage, particularly the arteries in the region of the wrists and ankles. Collateral circulation gives "tree root" or "spider leg" appearance. Angiograms may also show occlusions (blockages) or stenosis (narrowings) in multiple areas of both the arms and legs. Distal plethysmography also yields useful information about circulatory status in digits. To rule out other forms of vasculitis (by excluding involvement of vascular regions atypical for Buergers), it is sometimes necessary to perform angiograms of other body regions (e.g., a mesenteric angiogram).Skin biopsies of affected extremities are rarely performed because of the frequent concern that a biopsy site near an area poorly perfused with blood will not heal well. Prevention
The cause of the disease is thought to be autoimmune in nature and heavily linked to tobacco use in patients with Buergers as primary disease. Treatment
Smoking cessation has been shown to slow the progression of the disease and decrease the severity of amputation in most patients, but does not halt the progression. In acute cases, drugs and procedures which cause vasodilation are effective in reducing pain experienced by patient. For example, prostaglandins like Limaprost are vasodilators and give relief of pain, but do not help in changing the course of disease. Epidural anesthesia and hyperbaric oxygen therapy also have vasodilator effect. There is moderate certainty evidence that intravenous iloprost (prostacyclin analogue) is more effective than aspirin for relieving rest pain and healing ischemic ulcers.