Rapid short-duration hypothermia with cold saline and endovascular cooling before reperfusion reduces microvascular obstruction and myocardial infarct size.
BACKGROUND
The aim of this study was to evaluate the combination of a rapid intravenous infusion of cold saline and endovascular hypothermia in a closed chest pig infarct model.


METHODS
Pigs were randomized to pre-reperfusion hypothermia (n = 7), post-reperfusion hypothermia (n = 7) or normothermia (n = 5). A percutaneous coronary intervention balloon was inflated in the left anterior descending artery for 40 min. Hypothermia was started after 25 min of ischemia or immediately after reperfusion by infusion of 1000 ml of 4 degrees C saline and endovascular hypothermia. Area at risk was evaluated by in vivo SPECT. Infarct size was evaluated by ex vivo MRI.


RESULTS
Pre-reperfusion hypothermia reduced infarct size/area at risk by 43% (46 +/- 8%) compared to post-reperfusion hypothermia (80 +/- 6%, p < 0.05) and by 39% compared to normothermia (75 +/- 5%, p < 0.05). Pre-reperfusion hypothermia infarctions were patchier in appearance with scattered islands of viable myocardium. Pre-reperfusion hypothermia abolished (0%, p < 0.001), and post-reperfusion hypothermia significantly reduced microvascular obstruction (10.3 +/- 5%; p < 0.05), compared to normothermia: (30.2 +/- 5%).


CONCLUSIONS
Rapid hypothermia with cold saline and endovascular cooling before reperfusion reduces myocardial infarct size and microvascular obstruction. A novel finding is that hypothermia at the onset of reperfusion reduces microvascular obstruction without reducing myocardial infarct size. Intravenous administration of cold saline combined with endovascular hypothermia provides a method for a rapid induction of hypothermia suggesting a potential clinical application.
Götberg
Matthias
M
Department of Cardiology, Lund University Hospital, 221 85, Lund, Sweden. matthias.gotberg@med.lu.se
Olivecrona
Goran K
GK
Engblom
Henrik
H
Ugander
Martin
M
van der Pals
Jesper
J
Heiberg
Einar
E
Arheden
Håkan
H
Erlinge
David
D
D000818:Animals; D004195:Disease Models, Animal; D005260:Female; D006439:Hemodynamics; D007036:Hypothermia, Induced; D008279:Magnetic Resonance Imaging; D008297:Male; D009203:Myocardial Infarction / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D015425:Myocardial Reperfusion / Q000379:methods*; D015428:Myocardial Reperfusion Injury / Q000517:prevention & control*; D011897:Random Allocation; D013552:Swine