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Bidirectional shunt flow across a ventricular septal defect: pulsed Doppler echocardiographic analysis
B Stojnić1, P Pavlović, D Ponomarev
1Department of Cardiology, Military Medical Academy, Belgrade, Yugoslavia.
Insights
Pulsed Doppler echocardiography reveals bidirectional shunting in ventricular septal defect (VSD) patients with pulmonary hypertension. Early right-to-left shunting indicates severe pulmonary vascular obstructive disease (PVOD).
Area of Science:
- Cardiology
- Pediatric Cardiology
- Echocardiography
Background:
- Ventricular septal defect (VSD) can lead to pulmonary hypertension (PH) and pulmonary vascular obstructive disease (PVOD).
- Understanding shunt direction and timing is crucial for assessing VSD severity and associated pulmonary complications.
Purpose of the Study:
- To investigate the relationship between shunting patterns in VSD and the presence and severity of pulmonary vascular disease using pulsed Doppler echocardiography and hemodynamic data.
Main Methods:
- Pulsed Doppler echocardiography and hemodynamic assessments were performed on 31 patients with isolated VSD.
- Patients were categorized into three groups based on pulmonary hypertension and PVOD severity.
- Shunt direction and timing across the VSD were analyzed in relation to right and left ventricular pressures.
Main Results:
- Bidirectional shunting was observed in 9 out of 31 VSD patients, predominantly those with PH.
- Left-to-right shunting occurred with low to moderately elevated right ventricular pressures.
- Right-to-left shunting, particularly during diastole, emerged as right ventricular systolic pressure approached 60% of left ventricular systolic pressure.
- In Eisenmenger syndrome, right-to-left shunting occurred earlier (late systole) and persisted into diastole.
- An early occurrence of right-to-left shunting (index < 0.5 second) was a significant indicator of severe PVOD.
Conclusions:
- Pulsed Doppler echocardiography can effectively characterize shunting dynamics in VSD patients.
- The timing and direction of shunting across the VSD provide valuable insights into the severity of pulmonary hypertension and PVOD.
- Early detection of right-to-left shunting is critical for identifying severe PVOD in VSD patients.
Abstract:
Pulsed Doppler echocardiographic and hemodynamic examinations were performed in 31 patients (mean age 17.8 years) with isolated ventricular septal defect (VSD). Three groups were studied: group I (n = 6) patients 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 detected in 9 VSD patients (6 in group I and 3 in group II). Patients with 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 60% of the left ventricular pressure, right-to-left shunting occurred across the defect during early and mid diastole. However, in patients with Eisenmenger syndrome (group I) the right-to-left shunting occurred during late systole with continuation during the early and mid diastolic period. The earlier occurrence of right-to-left shunting (index < 0.5 second) signifies the presence of severe PVOD.