A simple technique for bedside estimation of left atrial pressure.

Abstract

Distinguishing cardiac from noncardiac causes of dyspnea is clinically important, and a reliable noninvasive measure of left atrial pressure (LAP) is needed. Subtracting the peak systolic gradient between left ventricle (LV) and left atrium (LA) from the central systolic blood pressure (BP) should provide this measure. Using a commercially available blood pressure system incorporating applanation tonometry and bedside echocardiography, we tested this hypothesis in a broad spectrum of patients. A total of 75 stable patients, scheduled for right heart catheterization for any reason, were included. Central systolic pressure was measured by a Sphygmocor® tonometry system; peak LV-LA gradient was calculated as 4*(peak mitral regurgitation (MR) velocity)2 . Microbubble contrast was used as needed to augment the MR signal. LAP estimates using central BP were compared with wedge pressure as were LAP estimates using brachial BP. Left atrial pressure estimates using central BP showed a good correlation with wedge pressure (r2 =0.774, P<.0001) while estimates using brachial systolic BP did not (r2 =0.157, P=.0006). Using central BP, correlations between LAP and wedge were similar among groups with varying degrees of MR and normal vs reduced ejection fraction. The use of central systolic BP and peak LV-LA gradient by bedside echocardiography holds promise as a noninvasive measure of LAP. Our results are similar to those provided using current guidelines for echocardiographic estimation of LAP. Increased precision in the measurement of LV-LA gradient would improve the accuracy of this new technique.