Effects of radial left ventricular dyssynchrony on cardiac performance using quantitative tissue Doppler radial strain imaging.
Our objective was to test the hypothesis that novel angle-corrected radial strain imaging can quantify left ventricular dyssynchrony associated with contractile impairment and improved with biventricular pacing. Eight open-chest dogs were studied by novel angle-corrected color-coded radial strain imaging and high-fidelity pressure-conductance catheters recording pressure-volume loops. Heart rate was controlled by right atrial pacing and all timing intervals were corrected by R-R interval (corrected interval = measured interval/(R-R interval)(1/2)). Left bundle branch block, simulated by right ventricular free wall pacing, resulted in marked radial dyssynchrony, which we defined as maximal time difference between peak segmental strain, from 39 +/- 17 to 354 +/- 49 milliseconds and stroke work decreased from 157 +/- 40 to 60 +/- 37 mJ, (P < .005 vs baseline). Depression of contractility by high-dose esmolol (end-systolic pressure-volume relationship from 5.7 +/- 2.4 to 3.6 +/- 1.0 mm Hg/mL) was associated with augmented dyssynchrony to 388 +/- 53 milliseconds (P < .05 vs baseline right ventricular pacing). Biventricular pacing improved dyssynchrony to 55 +/- 19 milliseconds and stroke work to 143 +/- 33 mJ (P < .05 vs right ventricular pacing). Changes in radial dyssynchrony correlated significantly with 6-site average regional strain (r = -0.93 +/- 0.05 individually, r = 0.80 overall) and stroke work (r = -0.88 +/- 0.12 individually, r = -0.82 overall). Angle-corrected radial strain imaging has clinical potential to quantify mechanical dyssynchrony and effects of biventricular pacing.
Dohi
Kaoru
K
Division of Cardiovascular Disease, Critical Care Medicine Department, University of Pittsburgh, Pittsburgh, Pennsylvania 15213-2582, USA.
Pinsky
Michael R
MR
Kanzaki
Hideaki
H
Severyn
Donald
D
Gorcsan
John
J
D000818:Animals; D002304:Cardiac Pacing, Artificial; D004285:Dogs; D015150:Echocardiography, Doppler / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D011379:Prognosis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D013318:Stroke Volume; D016896:Treatment Outcome; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging* / Q000209:etiology; D014693:Ventricular Fibrillation / Q000150:complications / Q000000981:diagnostic imaging* / Q000517:prevention & control*