This girl has a very small VSD. Such a minor shunt does not burden the circulation at all nor does it limit physical performance in even the most strenuous physical activity. Endocarditis prophylaxis might, however, be recommended. On auscultation the murmur is a very early systolic whistling high-pitched blow. The phonogram shows that it begins immediately from the first heart sound and extends only over one fourth of the systole. This shows that VSD can be very small and that the contraction of the heart soon closes the shunt. Sometimes a high-pitched whistle is associated with such a VSD as the rapid flow causes the ventricle wall around the shunt to vibrate at a high frequency. Because the flow velocity increases as the shunt becomes smaller, the frequency of the vibration also rises. This vibration is seen around 700 Hz as an ascending configuration. Age 4.1 years. Area of auscultation: left fourth ic (LIC4).