Intra-Operative Measurement of the Superior Vena Caval Flow Pattern in Patients with Intracardial Shunts

In 17 cases of intracardial shunts, 15 atrial septal defects and two ventricular septal defects, the instantaneous superior vena caval flow pattern was recorded and related to the right atrial and right ventricular pressures. The atrial systolic A flow was found reversed/ zero in sinus tachycardia (heart rate ≥ 90 beats/min) in the majority of uncomplicated atrial septal defects, primum and secundum types. This finding may reflect shunt flow. In three cases of tricuspid incompetence and atrial septal defect, secundum type, the insufficient valve function was revealed by flow tracing and confirmed at operation. The mitral split in atrial septal defects, primum type, had no haemodynamic significance in our cases.