Pressure Gradients in the Atria and Pulmonary Veins in Man

Abstract

Summary

1. During cardiac catheterization, a pressure gradient was found between a distal point in a pulmonary vein and either or both atrial chambers during the major portion of the cardiac cycle in 2 cases of atrial septal defect, in a third case wherein an anomalous pulmonary vein drained into the right atrium, and in a fourth in which an anomalous pulmonary vein emptied into the superior vena cava.

2. The magnitude of the gradient between pulmonary vein and right atrium varied from 3.0 to 5.8 mm of mercury with an average value of 4.2 mm in the 4 cases studied.

3. Evidence that this gradient could not be entirely due to an end pressure or Pitot effect was obtained from study of a model in which the end pressure effect was shown to be 0.5 to 0.8 mm of mercury at the same calculated flow velocities.

4. It is suggested that this pressure gradient is a result of the pressure transmitted by the right ventricle through the pulmonary circulation, and is an important factor in the left-to-right shunt observed at rest during quiet breathing in uncomplicated cases of atrial septal defect.