Low flow after global ischemia to improve postischemic myocardial function and bioenergetics.
OBJECTIVE
In this study, we test the hypothesis that a period of low flow perfusion before full reperfusion improves ventricular function and bioenergetics.


METHODS
Prospective, randomized, controlled animal study.


METHODS
Research laboratory.


METHODS
Sprague-Dawley rats.


METHODS
Hearts were perfused with Krebs-Henseleit buffer at 85 mm Hg. The protocol consisted of 10 mins of baseline flow, 15 mins of global ischemia, 5 mins of low flow ischemia, and 30 mins of reperfusion. Groups received 10% or 1% of baseline flow during the low flow period. A control group received 0% low flow (20 mins of global ischemia).


RESULTS
Left ventricular function was continuously measured. Hearts were freeze-clamped at various time points, and metabolites were measured. At 10% flow, following global ischemia, both left ventricular function and bioenergetics improved compared with 0% flow and 1% flow. At 1% flow, no changes in function were seen and adenosine 5'-triphosphate concentrations decreased during reperfusion, compared with no flow (9.4 +/- 1.0 vs. 13.2 +/- 1.0 micromol/g of dry weight, p <.01).


CONCLUSIONS
Following global ischemia but before full reperfusion, a period of low flow improves postischemic myocardial function and energetic recovery, only if a certain level of low flow is met. Very low flow may further reduce bioenergetic recovery without improvement in postischemic function, compared with continuous global ischemia.
Klawitter
Paul F
PF
Department of Emergency Medicine, The Ohio State University, Columbus, OH 43210, USA.
Murray
Holt N
HN
Clanton
Thomas L
TL
Palmer
Brian S
BS
Angelos
Mark G
MG
D000704:Analysis of Variance; D000818:Animals; D016887:Cardiopulmonary Resuscitation; D004734:Energy Metabolism; D006323:Heart Arrest / Q000503:physiopathology / Q000628:therapy*; D008297:Male; D015425:Myocardial Reperfusion / Q000379:methods*; D017682:Myocardial Stunning / Q000503:physiopathology; D011446:Prospective Studies; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors; D016277:Ventricular Function, Left