Abnormal pattern of flow in the superior caval vein in children after open heart surgery.

To investigate the pattern of flow in the superior caval vein in children after open heart surgery, we examined the flow velocity curves in 37 patients who had undergone surgical correction of either ventricular or atrial septal defects. The control group consisted of 64 age-matched children. We used pulsed Doppler examinations to record the velocity curves. We measured the highest and lowest peak flow velocities during systole and diastole, and calculated ratios for the various measurements. We found that the velocity of the wave in systole is lower than that of the wave in diastole in the postoperative patients, which is contrary to the normal pattern. The velocity in systole increases more than that in diastole during inspiration, which is also different from the normal pattern. The change in pattern of flow velocity curve during respiration was smaller in patients after surgery than in normal subjects, which might indicate that there is less reserve ability in the right atrium in postoperative patients.