Determination of pressure in the pulmonary artery by external graphic recordings.

Abstract

A method for determining the systolic pulmonary arterial pressure by external graphic recordings was described. The technique was based upon measuring the phase of isometric relaxation of the right ventricle (IIp-T interval). The factors that determine the duration of the IIp-T interval are the right atrial pressure which, in the absence of tricuspid stenosis or insufficiency or right heart failure, remains normal; the systolic pulmonary arterial pressure which, when raised, retards the opening of the tricuspid valve and proportionately prolongs the np-T invertal; and the heart rate which is inversely related to the duration of the IIp-T. The np-T inverval and the heart rate were used to calculate the systolic pulmonary arterial pressure by external graphic recordings. The results on 120 cases were included. The figures were compared with those obtained in the same patients by cardiac catherization.