LEFT-VENTRICULAR PERFORMANCE ASSESSED BY ECHOCARDIOGRAPHIC AUTOMATED BORDER DETECTION AND ARTERIAL-PRESSURE

Automated echocardiographic measures of left ventricular (LV) cavity a rea are closely correlated with changes in volume and can be coupled w ith LV pressure (P-LV) to construct pressure-area loops in real time. The objective was to rapidly estimate LV contractility from end-systol ic relationships of cavity area las a surrogate for LV volume) and cen tral arterial pressure (P-a) (as a surrogate for P-LV) in a canine mod el using automated algorithms. In eight anesthetized mongrel dogs, we simultaneously measured P-LV, LV area, and P-a (fluid-filled catheter) . End-systolic pressure-area relationships [in terms of pressure-area elastance (E'(es))] from pressure-area loops during inferior vena cava l occlusions were determined during basal conditions (control), dobuta mine infusion (5-10 mu g . mg(-1). min(-1)), and after bolus propranol ol (2 mg/kg) with both P-LV and P-a by semiautomated and automated ite rative regression methods. E'(es) increased during dobutamine infusion and decreased after propranolol infusion in all animals and with all iterative methods. Estimates of E'(es) from P-a were closely correlate d with E'(es) from P-LV by both the semiautomated and automated method s (r = 0.93; P<0.01). The relationship between E'(es) obtained from P- a for the two methods was also closely correlated. Although the automa ted methods displayed larger differences from the semiautomated iterat ive technique by Bland-Altman analysis, the change in E'(es) with all techniques during dobutamine infusion and after propranolol infusion w as of similar magnitude and direction among the three techniques. Grea ter variability with the dobutamine runs was partially due to abnormal ly conducted Ventricular beats that minimized the number of consecutiv e beats that could be used for these analyses. We conclude that on-lin e P-a recordings from fluid-filled catheters can be used with echocard iographic automated border detection to rapidly calculate E'(es) as a means to estimate LV contractility.