Load dependence of left atrial and left ventricular filling dynamics by transthoracic and transesophageal Doppler echocardiography

Abstract

This article evaluates the pattern and effect of varying loading conditions on pulmonary venous flow and transmitral flow obtained by transthoracic and transesophageal echocardiography. We have conducted a two-stage study. A transthoracic echocardiographic study was performed in 15 patients with coronary artery disease and preserved left ventricular function. The transesophageal approach was used before open heart surgery where hemodynamic conditions were invasively monitored. Sublingual nitroglycerin (NTG) was administered to lower systolic blood pressure (mean 18 mm Hg) and resulted in a significant decrease in the peak passive left ventricular diastolic filling velocity (E wave) from 72 +/- 23 to 49 +/- 16 cm/s without marked changes in pulmonary venous flow pattern. In the transesophageal part of the study, Doppler-derived systolic (J), diastolic (K), and retrograde (R) phases of pulmonary venous flow, and passive (E) and active (A) phases of mitral flow were measured. Hemodynamic data were obtained invasively. Loading conditions were increased by infusion of saline and phenylephrine and reduced by NTG. Increased preload resulted in an augmented mitral E wave, an increased J wave, and an increased retrograde flow wave from the pulmonary veins. These changes were reversed by reduction of preload with NTG. Monitoring mitral and pulmonary venous flow may provide a relatively noninvasive means to assess directional changes in left ventricular preload.