ACOUSTIC QUANTIFICATION INDEXES OF LEFT-VENTRICULAR SIZE AND FUNCTION- EFFECTS OF SIGNAL AVERAGING

Background: The aim of this study was to evaluate the clinical utility of using signal-averaged acoustic quantification (SAAQ) waveforms for improved assessment of left ventricular (LV) size and function. Metho ds and Results. Pour separate protocols were performed in 47 subjects. SAAQ waveforms were used to assess alterations in LV function induced by dobutamine (15 mu g/kg per minute) and esmolol (200 mu g/kg per mi nute) in eight normal subjects. Subsequently, we analyzed SAAQ wavefor ms obtained in 12 patients with LV dysfunction secondary to dilated ca rdiomyopathy and 12 age-matched normal subjects. Finally, we developed computer software for monitoring of LV function on the basis of conti nuous acquisition and repeated analysis of SAAQ waveforms. We compared the interbeat variability in indexes of LV function obtained from raw AQ and SAAQ during 10 minutes of steady-state monitoring in eight pat ients undergoing transesophageal echocardiography. The feasibility of long-term monitoring in the intensive care setting was then studied in seven patients undergoing abdominal surgery. Our analysis tracked var iations in LV function induced by dobutamine and esmolol. Significant differences in all measured indexes were found between normal subjects and patients with. dilated cadiomyopathy. Signal averaging during ste ady-state monitoring significantly reduced the interbeat variability o f all indexes (21% to 42%). In the operating room, the SAAQ monitoring system tracked hemodynamic changes in close agreement with invasive m easurements. Conclusions. SAAQ allows fast and easy quantification of LV function and can track hemodynamic trends in the operating room set ting.