Importance of atrial systole to ventricular filling predicted by transesophageal echocardiography

Abstract

This study documented mitral flow velocity patterns in anesthetized patients with ischemic heart disease and left ventricular dysfunction and investigated the relationship between transmitral flow velocity measurements and the hemodynamic response to ventricular pacing. Twenty-four patients in sinus rhythm without evidence of mitral valve disease undergoing electrive myocardial revascularization were studied. Anesthesia consisted of a high-dose opioid-muscle relaxant-oxygen technique. After endotracheal intubation a 3.5-MHz phased-array transesophageal echocardiographic probe was inserted and positioned to obtain a long-axis view of the left atrium and left ventricle. The Doppler sample volume was placed at the mitral annulus with minimal cursor angulation, and the biphasic velocity tracing of transmitral blood flow was recorded. A hemodynamic profile was obtained, and cardiac output was measured in triplicate by thermodilution. Ventricular pacing was then instituted and the hemodynamic and thermodilution measurements were repeated. The peak early filling (E) velocity was 0.34 ± 0.11 m/s, and the peak atrial (A) velocity was 0.38 ± 0.09 m/s. The mean E:A ratio was 0.91 ± 0.3, and the median value was 0.88. In sinus rhythm the cardiac index of those patients with an E:A > 0.88 (group 1) was 1.97 ± 0.32 l/min and those with an E:A < 0.88 (group 2) was 1.76 ± 0.50 (NS). During ventricular pacing the patients in group 1 (1.56 ± 0.32 l/min) had significantly higher cardiac indices than those in group 2 (1.21 ± 0.31 l/min) (P < 0.02). It is concluded that peak E velocities and E:A ratios are markedly lower in anesthetized patients with ischemic heart disease whose lungs are mechanically ventilated than in awake normals and that patients with E:A ratios < 0.88 had more marked decreases in cardiac index with the loss of atrial contraction during ventricular pacing.