Effect of Microembolization on Left Ventricular Systolic Wall Motion and Dyssynchrony Using Dipyridamole Stress Two-dimensional Speckle Tracking Imaging: An Experimental Study

摘要

Objectives: To investigate whether subtle myocardial injury caused by coronary microembolization (CME) can induce left ventricular contractile dysfunction or dyssynchrony on swine models.Materials and methods: CME swine models were constructed by the injection of 150,000 micro-spheres into the left coronary artery compared with the control group. The peak systolic values of longitudinal strain (LS), radial strain (RS), and circumferential strain (CS) by two-dimensional speckle tracking imaging (2D-STI) were measured under resting stage and dipyridamole stress prior to, 6 hours after, and 1 week after CME. The mean standard deviation of 12 segmental time-to-peak longitudinal strain (Tls-12SD), radial strain (Trs-12SD), and circumferential strain (Tcs-12SD) of the left ventricle were calculated as the dyssynchrony index. Results: Postmortem analysis demonstrated 29.76% of the left'ventricular segments manifested myocardial necrosis in MCE group compared with the control group (0%, p < 0.01). Left ventricular ejection fraction had no significant differences throughout the entire study (p > 0.05). In the CME group, compared with the baseline, LS on the basal anterior wall deteriorated from -9.72 ± 4.96 % to -6.35 ± 3.75 % (p < 0.05) and Tcs-12SD was prolonged from 85.00 i 35.74 ms to 151.30 ± 75.14 ms at 1 week (p < 0.01) under resting stage. After dipyr-idamole infusing, a further decrease of contractility on all CME-related segments occurred at 6 hours and/or 1 week (p < 0.05-0.01). The deterioration of Tls-12SD achieved statistical significance at 1 week (157.66 ± 78.25 ms vs. 112.54 ± 62.52 ms, p < 0.05). Furthermore, Tcs-12SD was progressively delayed from 6 hours to 1 week (148.30 ± 45.53 ms and 162.45 ± 51.67 ms vs. 78.00 ± 40.17 ms, all p < 0.01).Conclusion: Subtle cardiac systolic dysfunction as well as dyssynchrony caused by CME can be detected using dipyridamole stress 2D-STI sensitively. Moreover, left ventricular dyssynchrony could be affected even by slight myocardial injury.