Systolic Murmurs - VSD

     You are listening to the typical murmur of a ventricular septal defect. It is usually best heard over the “tricuspid area”, or the lower left sternal border, with radiation to the right lower sternal border because this is the area which overlies the defect. It is characteristically a holosystolic murmur because the pressure difference between the ventricles is generated almost instantly at the onset of systole, with a left to right shunt continuing throughout ventricular contraction. If the defect persists without treatment, irreversible pulmonary hypertension may develop with reversal of the shunt into a right to left flow pattern (Eisenmenger syndrome). There is usually no diastolic component to the murmur, as the pressure between the ventricles during diastole is not sufficiently different to generate an audible flow.

     Because the flow pattern is usually left to right, the right ventricle suffers from volume overload and takes longer to eject the stroke volume. This causes a slight delay in the closing of the pulmonary valve, and a widely split S2 may result.