Left Ventricular Function after Acute Ischemia-Reperfusion Injury in Cardiac Decentralized Dogs Subject to Ischemic Conditioning
Kingma JG Jr, Simard D, Rouleau JR.
Objective: Ischemic conditioning (IC) mediated protection against ischemic injury continues independent of extrinsic cardiac nerve status; however, controversy persists regarding its ability to limit ischemia-mediated LV contractile dysfunction. Here, we investigate the acute cardiac consequences of loss of sympathetic and parasympathetic inputs to the local cardiac neuronal hierarchy on post-ischemic LV function. Additionally, we examined whether IC could affect potential recovery of LV function. Methods: Anesthetized, open-chest dogs were randomly distributed to surgical nerve ablation or ganglionic blockade (hexamethonium bromide) groups; each group comprised dogs subject to IC. All dogs were exposed to 60-min acute coronary occlusion (CO) followed by 180-min reperfusion (REP). IC consisted of 4 cycles of 5-min CO and 5-min REP of the left main coronary artery. LVP-V relations were constructed by inferior vena cava occlusion at different times before and during CO-REP. The load insensitive conductance catheter method was used to evaluate LV contractility, diastolic function and ventriculoarterial arterial coupling. Results: We found robust protection against necrosis in all IC treated dogs that was not abrogated by nerve ablation or ganglionic blockade; however, LV contractile functional status did not improve. Parameters of LV function were not markedly different between groups; however, statistical significance was observed during CO-REP between nIC and IC groups. These changes were similar regardless of the method used for cardiac decentralization. Conclusions: Diminished LV contractile function produced by CO-REP did not recover with IC pre-treatment; cardiac decentralization (surgical or pharmacologic) did not markedly affect outcomes.
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