Myocardial protection by a left ventricular assist device during reperfusion following acute coronary occlusion

Abstract

To evaluate the effects of a left ventricular assist device (LVAD) during the reperfusion period following acute coronary occlusion, sixteen mongrel dog hearts were subjected to 1 hour's occlusion of the circumflex coronary artery and then reperfused for 6 hours. In seven control dogs (control group), the hearts were reperfused without any support. In nine LVAD dogs (LVAD group), however, the left ventricles were supported by the application of a pneumatic driven diaphragm-type pump for 5 hours and then reperfused for another hour without any device. Triphenyltetrazolium chloride was used to determine the extent of infarction. The results showed a significant reduction in the area of infarct (AI) as a percentage of the area at risk (AR) in the LVAD group compared with the control group, the AI/AR being 22.3 per cent for the control group versus 4.8 per cent for the LVAD group (p less than 0.05). The cardiac output was also significantly higher in the LVAD group compared with the control group. The per cent systolic shortening in the ischemic region of the LVAD group showed a significantly better recovery, being 75.8 per cent for the LVAD group versus 24.4 per cent for the control group (p less than 0.01). It was concluded that the application of a LVAD during reperfusion after 1 hour's coronary occlusion results in a significant reduction of infarct size and provides improvement in both regional and global cardiac function.

Acute myocardial infarction enhances the portal venous histamine level in dogs

“…The hemodynamic data of our experiments during acute coronary artery occlusion and reperfusion are similar to the data published by other authors [24,25]. The MAP, SV, CO and CI decreased during constant coronary artery occlusion, while the peripheral vascular resistance increased.…”

Left Ventricular Assist Devices for Acute Myocardial Infarct Size Reduction: Meta-analysis

“…These 26 studies evaluated a total of 488 animals, including 265 subjects assisted with either surgical or percutaneous LVAD. Types of LVAD included trans-valvular pumps in 13 studies (Impella in nine studies [10,[16][17][18][19][20][21][22][23]; Hemopump in four studies [24][25][26][27]); LV-distal arterial bypass in four studies (2 LV-femoral artery [28,29]; 1 LV-carotid artery [30]; and 1 LV-descending aorta [31]), left atrial-femoral artery bypass in five studies [29,[32][33][34] (including one TandemHeart study [35]), left atrial-ascending aorta bypass in one study [36], and right atrial-femoral/subclavian artery bypass in six studies [17,32,37] (3 studies with LV vent [38][39][40]) (Fig. 2).…”

Percutaneous mechanical cardiac assist in myocardial infarction. Where are we now, where are we going?

“…This left ventricular unloading, hypothetically, might result in infarct size reduction and increased left ventricular recovery. Several experimental studies have provided positive evidence for this hypothesis (6)(7)(8)(9). Although the underlying physiology is not yet completely understood, several mechanisms could play a role.…”

“…The concept of reduction of myocardial workload and reduction of myocardial oxygen demand through unloading is already used pharmacologically (ACE inhibitors). Furthermore, several experimental studies showed improved myocardial salvage and reduction of infarct size with mechanical unloading (6)(7)(8)(9). Surgical LVAD therapy is too cumbersome and associated with too much morbidity to become a serious strategy in STEMI patients without CS with the single purpose of myocardial recovery.…”