Usefulness of Blalock-Taussig shunt Doppler flow velocity profiles in the assessment of pulmonary artery pressure and flow.

AIM

To assess the utility of continuous wave Doppler evaluation of velocity profiles across a Blalock-Taussig (BT) shunt in the evaluation of pulmonary artery pressure and pulmonary blood flow.

METHODS AND RESULTS

Eleven children with complex congenital heart disease with a BT shunt as the sole source of pulmonary blood supply were studied prospectively (median age 5 (0.3-21) months). Doppler evaluations of shunt flow velocity profile and cardiac catheterization were carried out simultaneously. Pulmonary artery pressure and flow were estimated using the modified Bernoulli equation and velocity time integral of shunt flow. There was a positive correlation between (1) the Doppler estimates for mean pulmonary artery pressure, using the diastolic flow velocity, and the mean pulmonary venous wedge pressure ( r = 0.93, SEE = 1.0 mmHG; P<0.001 ) and (2) the Doppler derived and calculated pulmonary blood flow ( r = 0.9, SEE = 0.19 l/min; P<0.001). In contrast, the Doppler estimates for mean pulmonary artery pressure using the peak or mean Doppler gradients were poor.

CONCLUSION

The diastolic BT shunt flow velocity can be used reliably to predict mean pulmonary artery pressure when a BT shunt is the sole source of pulmonary artery flow. There was agreement between Doppler predicted pulmonary blood flow and catheter based calculations. These findings may prove a useful tool for perioperative management.