BIDIRECTIONAL SHUNT FLOW ACROSS A VENTRICULAR SEPTAL-DEFECT - PULSED DOPPLER-ECHOCARDIOGRAPHIC ANALYSIS

Pulsed Doppler echocardiographic and hemodynamic examinations were per formed in 31 patients (mean age 17.8 years) with isolated ventricular septal defect (VSD). Three groups were studied: group I (n = 6) patien ts had severe pulmonary vascular obstructive disease (PVOD); group II (n = 12) patients had pulmonary hypertension (PH) without severe PVOD; group III (n = 13) patients had no PH. Bidirectional shunting was det ected in 9 VSD patients (6 in group I and 3 in group II). Patients wit h low to moderately elevated right ventricular pressures demonstrated left-to-right shunting across the defect throughout the cardiac cycle. When systolic pressure in the right ventricle reached approximately 6 0% of the left ventricular pressure, right-to-left shunting occurred a cross the defect during early and mid diastole. However, in patients w ith Eisenmenger syndrome (group I) the right-to-left shunting occurred during late systole with continuation during the early and mid diasto lic period. The earlier occurrence of right-to-left shunting (index < 0.5 second) signifies the presence of severe PVOD.