Valvular heart disease

Abstract

It has been previously shown In both experimental and clinical studies that viable but stunned myocardium exhibits a cardiac cycle-dependent variation of integrated backscatter whereas infarcted myocardium does not To define the clinical utility of integrated backscatter imaging for identification of viable myocardium in patients (pts) with chronic left ventricular (LV) techerrdc dysfunction, we studied 14 pts (59 10 years) with coronary disease and segments! dysfunction. Cyclic variations of integrated backscatter and wail thickening were measured by transesophageal echocardiography, whereas presence of viable myocardium was evaluated by quantitative dobutamine echocarcfiography (5-10 /tg/kg/min). The average magnitude of cyclic variations was 4.07 1.67 dB in remote normal segments, compared with 2.12 2.36 dB In dysfunctional segments (p < 0.05). According to their contractile response to dooutamine, dysfunctional segments were further categorized into viable (Improved wall motion by > 1 grade in 2 adjacent akinetic segments) and nonviable. At baseline, % wall thickening was similar In viable and nonviable segments (4 2 vs. 3 2%). With dooutamine, % wall thickening increased only In viable segments (to 34 13 vs. 2 4% In nonviable segments, p < 0.01). The magnitude of cyclic variations of Integrated backscatter was larger In viable (4.12 1.62 dB, p = ns vs. remote) than in nonviable segments (0.12 0.75 dB, p < 0.01 vs. viable and remote). The delay of cyclic variation expressed as time to nadir over QT interval was similar In viable and nonviable segments (1.08 0.23 vs. 1.15 0.46). Our data indicate that only viable myocardium exhibits cardiac cycle-dependent variations of Integrated backscatter. Their analysis may thus provide a useful Index of the presence of viable and potentially salvageable myocardium In patients with chronic LV Ischemic dysfunction.