Prolonged myocardial hypoperfusion for up to 24 hours in pigs resulted in a progressive loss of perfusion-contraction matching, with work index decreasing to 18% of baseline despite unchanged blood flow.
Prolonged moderate ischemia in a pig model leads to a progressive loss of perfusion-contraction matching and reduced calcium responsiveness.
It is unclear whether perfusion-contraction matching (PCM) is maintained during prolonged myocardial ischemia. In 27 anesthetized pigs, left anterior descending coronary arterial inflow was reduced to decrease an anterior work index (WI) at 5 min of hypoperfusion by 40% and then maintained at this level for 12 or 24 h. With 12 h of hypoperfusion, the myocardium remained viable in 6 of 7 pigs (with triphenyltetrazolium chloride; TTC) and with 24 h of hypoperfusion in 5 of 11 pigs (TTC, histology). The reduction in WI to 62 +/- 4 and 62 +/- 3% of baseline in the two groups was matched to the reduction of transmural blood flow (TBF; microspheres) at 5 min of hypoperfusion, averaging 59 +/- 4 and 60 +/- 2% of baseline. With prolonged hypoperfusion, WI decreased to 30 +/- 5% at 12 h and 18 +/- 3% at 24 h; TBF remained unchanged (53 +/- 4 and 54 +/- 4%). The added calcium concentration required for the half-maximal increase in WI increased from 121 +/- 25 microg/ml blood at baseline to 192 +/- 26 microg/ml blood at 12 h of hypoperfusion. Thus, with hypoperfusion for 24 h, PCM is progressively lost, and calcium responsiveness is reduced.
Schulz et al. (Tue,) conducted a other in Myocardial ischemia (n=27). Prolonged hypoperfusion vs. Baseline / 5 min hypoperfusion was evaluated on Perfusion-contraction matching (work index and transmural blood flow). Prolonged myocardial hypoperfusion for up to 24 hours in pigs resulted in a progressive loss of perfusion-contraction matching, with work index decreasing to 18% of baseline despite unchanged blood flow.
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