In normal hearts, myocardial perfusion is fairly well matched to regional metabolic demand, although both are distributed heterogeneously. Nonuniform regional metabolic vulnerability during coronary stenosis would help to explain nonuniform necrosis during myocardial infarction. In the present study, we investigated whether metabolismperfusion correlation diminishes during coronary stenosis, indicating increasing mismatch of regional oxygen supply to demand. Thirty anesthetized male pigs were studied: controls without coronary stenosis (n = 11); group I, left anterior descending (LAD) coronary stenosis leading to coronary perfusion pressure reduction to 70 mmHg (n = 6); group II, stenosis with perfusion pressure of about 35 mmHg (n = 6); and group III, stenosis with perfusion pressure of 45 mmHg combined with adenosine infusion (n = 7). [2-13C]-and [1,2-13C]acetate infusion was used to calculate regional O2consumption from glutamate NMR spectra measured for multiple tissue samples of about 100 mg dry mass in the LAD region. Blood flow was measured with microspheres in the same regions. In control hearts without stenosis, regional oxygen extraction did not correlate with basal blood flow. Average myocardial O2delivery and consumption decreased during coronary stenosis, but vasodilation with adenosine counteracted this. Regional oxygen extraction was on average decreased during stenosis, suggesting adaptation of metabolism to lower oxygen supply after half an hour of ischemia. Whereas regional O2delivery correlated with O2consumption in controls, this relation was progressively lost with graded coronary hypotension but partially reestablished by adenosine infusion. Therefore, coronary stenosis leads to heterogeneous metabolic stress indicated by decreasing regional O2supply to demand matching in myocardium during partial coronary obstruction.

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American Journal of Physiology - Heart and Circulatory Physiology
Department of Intensive Care

Alders, D., Groeneveld, J., Binsl, T., & van Beek, J. (2015). Progressively heterogeneous mismatch of regional oxygen delivery to consumption during graded coronary stenosis in pig left ventricle. American Journal of Physiology - Heart and Circulatory Physiology, 309(10), H1708–H1719. doi:10.1152/ajpheart.00657.2014