The influence of remote ischemic post-conditioning on left ventricular mechanics

Abstract

Background: It is well known that remote ischemic postconditioning (RIPC) decreases infarct size and prevents left ventricular (LV) remodeling in patients with myocardial infarction. However, there is no study that evaluates the effect of RIPC on LV mechanics assessed by speckle tracking echocardiography. Therefore, we aimed to test the effects of RIPC on LV deformation parameters such as strain, strain rate, rotation and twist in healthy subjects. Methods: The study group consisted of 22 healthy subjects (28.9±4.2, 21-35), each with a structurally normal heart. The non-dominant arm was made ischemic by inflating the blood pressure cuff to a pressure of 200 mm Hg for 20 minutes. After index ischemia, the arm was allowed to undergo reperfusion for 10 seconds, after which the blood pressure cuff was inflated again to 200 mm Hg and the arm was made ischemic for 10 seconds. This deflation/inflation cycle was repeated a total of 3 times. TTE was obtained at baseline and repeated 30 minutes after the completion of these cycles. In TTE images, apical 4-3-2 chamber longitudinal strain/ strain rate, basal and apical circumferential strain/strain rate, and rotational parameters, such as basal rotation, apical rotation and LV twist, were recorded. Results: There were no significant differences in EDV, ESV, Simpson EF and heart rate before and after RIPC. Apical 4-3-2 chamber longitudinal strain and apical circumferential strain/strain rate measurements were comparable before and after RIPC, whereas basal circumferential strain was significantly decreased after RIPC (-23±3.4 vs -18.9±6.9, p=0.001). After RIPC, apical rotation was significantly increased (11.6±3.7 vs 16.7±4.0, p=0.0001) and basal rotation was significantly decreased (-6.1±2.1 vs -4.7±2.4, p=0.03). Consequently, net LV twist was significantly increased (17.4±4.5 vs 21.7±4.7). However, neither apical nor basal rotational rates showed any changes. Conclusions: We proposed that remote ischemic post-conditioning affects the rotational mechanics of the heart rather than longitudinal mechanics. These results might give new insights into understanding the favorable effects of the postconditioning.