Background: Emerging data suggest women have worse outcomes than men following cardioplegia and cardiopulmonary bypass (CP/CPB). Altered coronary microvascular function affecting myocardial perfusion may contribute, but human translational studies are lacking.
Methods: Viable coronary microvessels (<200 μ m) were dissected from human atrial samples collected before and after CP/CPB from a subset of 108 patients enrolled. Ex vivo contractile responses to vasopressin were assessed using video microscopy. RNA deep-sequencing and immunoblotting were used to quantify gene and protein expression, respectively.
Results: Coronary microvessels exhibited increased vasopressin-induced contractile responses post-CP/CPB in males and females (p < 0.0001). Females exhibited a decrease in microvascular contractile response versus males pre- (p = 0.1) and post-CP/CPB (p = 0.09) which approached significance. Myocardial vasopressin 1a receptor levels were increased in females versus males (p = 0.001). Vasopressin-induced vasoconstriction predicted postoperative cardiac index.
Conclusions: Impaired coronary microvascular contractile responses in females jeopardizing myocardial perfusion may underlie worse outcomes following cardiac surgery.
Keywords: Coronary microvascular reactivity; Sex differences; Vasopressin.
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