Assessment of length-dependent regulation of myocardial function in coronary surgery patients using transmitral flow velocity patterns

Background: In a subset of coronary surgery patients, a transient increase in cardiac load by leg elevation resulted in a decrease in maximal rate of pressure development (dP/dt(max)) and a major Increase in end-diastolic pressure (EDP). This impairment of left ventricular (LV) function appeared to be related to a deficient length-dependent regulation of myocardial function. The present study Investigated whether analysis of transmitral flow patterns with transesophageal echocardiography constituted a noninvasive method to identify these patients. Methods: High-fidelity LV pressure tracings and transmitral flow signals were obtained in 50 coronary surgery patients during an increase in cardiac load by leg elevation. Using Linear regression analysis, changes in transmitral E-wave velocity and deceleration time (DT) were related to changes in dP/dt(max) and EDP. Results: Changes in dP/dt(max) with leg elevation were closely related to corresponding changes in E-wave velocity (r = 0.81; P < 0.001) and to changes in DT (r = 0.78; P < 0.001), Similarly, changes in EDP were related to changes in E-wave velocity (r = 0.83; P < 0.001) and to changes in DT (r = 0.84; P < 0.001), The decrease in dP/dt(max) and the major increase in EDP in some patients was associated with an increase in E-wave velocity and a decrease in DT, indicating development of a restrictive LV filling pattern. Conclusions: Impairment of LV function with leg elevation was associated with the development of a restrictive transmitral filling pattern. Analysis of transmitral flow patterns by means of transesophageal echocardiography therefore allowed noninvasive identification of a subset of coronary surgery patients with impaired length-dependent regulation of LV function.