Preclinical Research
Catheter-Based Transcoronary Myocardial Hypothermia Attenuates Arrhythmia and Myocardial Necrosis in Pigs With Acute Myocardial Infarction

https://doi.org/10.1016/j.jacc.2006.06.080Get rights and content
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Objectives

This study evaluated the efficacy of catheter-based transcoronary myocardial hypothermia (CTMH) in pigs with acute myocardial ischemia.

Background

Although it has been suggested that hypothermia therapy can attenuate myocardial necrosis, few applications have been accepted for clinical use.

Methods

This study comprises 2 substudies. In both studies, pigs underwent 60 min of coronary occlusion and 180 min of reperfusion. In study 1, after 15 min of coronary occlusion with an over-the-wire-type balloon (OTWB), pigs in the hypothermia group (H) (n = 13) were directly infused with 4°C saline into the coronary artery through the OTWB wire lumen (2.5 ml/min) for 60 min. Pigs in the normothermia group (N) (n = 15) received the same amount of 36.5°C saline. In study 2, pigs in the hypothermia-reperfusion group (HR) (n = 5) were infused with 4°C saline through the infusion catheter (8 ml/min) for 30 min with a later start (60 min after coronary occlusion), whereas simple reperfusion was used for the reperfusion group (R) (n = 6).

Results

Catheter-based transcoronary myocardial hypothermia was successful in both studies. In study 1, CTMH significantly decreased ventricular arrhythmia and the ratio of necrosis to ischemic risk area (H: 9 ± 2%; N: 36 ± 4%; p < 0.0001) with a significant reduction of enzyme leaks. In study 2, CTMH tended to reduce the ratio of necrosis (HR: 33 ± 2%; R: 45 ± 5%; p = 0.08). In both studies, CTMH significantly suppressed the increase of 8-iso-prostaglandin Fwhile preserving the coronary flow reserve.

Conclusions

Catheter-based transcoronary myocardial hypothermia reduced myocardial necrosis while preserving coronary flow reserve, due, in part, to attenuation of oxidative stress.

Abbreviations and Acronyms

APV
time-averaged peak velocity
CFR
coronary flow reserve
CKMB
creatinine kinase MB isozyme
cTnT
cardiac troponin T
LAD
left anterior descending coronary artery
LV
left ventricle/ventricular
LVdP/dtmax
peak positive first derivative of left ventricle
MI
myocardial infarction
OTWB
over-the-wire-type balloon
sVT
sustained ventricular tachycardia
tau
time constant of left ventricular relaxation
8-iso-PGF
8-iso-prostaglandin F

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