Mild hypothermia delays the development of stone heart from untreated sustained ventricular fibrillation - a cardiovascular magnetic resonance study

Abstract

Background'Stone heart' resulting from ischemic contracture of the myocardium, precludes successful resuscitation from ventricular fibrillation (VF). We hypothesized that mild hypothermia might slow the progression to stone heart.MethodsFourteen swine (27 ± 1 kg) were randomized to normothermia (group I; n = 6) or hypothermia groups (group II; n = 8). Mild hypothermia (34 ± 2°C) was induced with ice packs prior to VF induction. The LV and right ventricular (RV) cross-sectional areas were followed by cardiovascular magnetic resonance until the development of stone heart. A commercial 1.5T GE Signa NV-CV/i scanner was used. Complete anatomic coverage of the heart was acquired using a steady-state free precession (SSFP) pulse sequence gated at baseline prior to VF onset. Un-gated SSFP images were obtained serially after VF induction. The ventricular endocardium was manually traced and LV and RV volumes were calculated at each time point.ResultsIn group I, the LV was dilated compared to baseline at 5 minutes after VF and this remained for 20 minutes. Stone heart, arbitrarily defined as LV volume <1/3 of baseline at the onset of VF, occurred at 29 ± 3 minutes. In group II, there was less early dilation of the LV (p < 0.05) and the development of stone heart was delayed to 52 ± 4 minutes after onset of VF (P < 0.001).ConclusionsIn this closed-chest swine model of prolonged untreated VF, hypothermia reduced the early LV dilatation and importantly, delayed the onset of stone heart thereby extending a known, morphologic limit of resuscitability.

Left ventricular diastolic dysfunction during acute myocardial infarction: Effect of mild hypothermia

“…The loss of LV compliance after CME in the present study resembles the “stone heart” after untreated cardiac arrest, which results from ATP loss and subsequent cardiomyocyte contracture 19,20 . Cooling in isolated rat hearts (28 °C) 19 and pigs in vivo (33 °C) 21 delayed the onset of a stone heart, and a similar effect within the embolized LV territory and the hypoperfused but viable infarction border zones may underlie better preserved LV compliance during MH in the present study.…”

Importance of Both Early Reperfusion and Therapeutic Hypothermia in Limiting Myocardial Infarct Size Post–Cardiac Arrest in a Porcine Model

“…The benefit of mild therapeutic hypothermia on post resuscitation myocardial dysfunction has also been reported. We found that mild hypothermia has a profound effect in lengthening the time period of untreated ventricular fibrillation before "stone heart" or global ischemic contracture of the left ventricle develops (32). Another report showed that mild post resuscitation hypothermia ameliorates some of the myocardial dysfunction commonly seen post cardiac arrest (33).…”

Dynamin‐related protein 1 (Drp1)‐mediated diastolic dysfunction in myocardial ischemia‐reperfusion injury: therapeutic benefits of Drp1 inhibition to reduce mitochondrial fission

“…In addition, it appears that Drp1 inhibition is protective when initiated in the reperfusion stage of IR injury. Improving the lusitropic properties of the heart and counteracting the “stone heart” seen in clinical cardiac arrest (35, 36) could have significant clinical benefit. Its benefits may also extend to other ischemic heart conditions, including acute coronary syndromes and postcardiovascular bypass surgery.…”