Poorly controlled hypertension is associated with increased coronary myogenic tone in patients undergoing cardiac surgery with cardiopulmonary bypass

Objective: Cardioplegia and cardiopulmonary bypass dysregulate coronary vaso-motor tone, which can be further affected by common comorbidities in patients undergoing cardiac surgery. This study investigates differences in coronary myogenic tone and vasomotor responses to phenylephrine before and after cardi-oplegia and cardiopulmonary bypass based on hypertension history.Methods: Coronary arterioles before and after cardioplegia and cardiopulmonary bypass were dissected from atrial tissue samples in patients with no hypertension, well-controlled hypertension, or uncontrolled hypertension, as determined by documented history of hypertension, antihypertensive agent use, and clinical blood pressure measurements averaged over 1 year. Myogenic tone in response to step-wise increases in intraluminal pressure was studied between pressure steps. Micro-vascular reactivity in response to phenylephrine was assessed via vessel myography. Protein expression was measured with immunoblotting.Results: Coronary myogenic tone was significantly increased in the uncontrolled hy-pertension group compared with the no hypertension and well-controlled hyperten-sion groups before cardioplegia and cardiopulmonary bypass at higher intraluminal pressures, and after cardioplegia and cardiopulmonary bypass across all intraluminal pressures (P < .05). Contractile responses to phenylephrine were significantly enhanced in patients in the uncontrolled hypertension group compared with the well-controlled hypertension group before cardioplegia and cardiopulmonary bypass, and in the uncontrolled hypertension group compared with the no hypertension and well-controlled hyertension groups after cardioplegia and cardiopulmonary bypass (P < .05). There were no differences in myogenic tone or phenylephrine-induced reactivity between the no hypertension and well-controlled hypertension groups (P >.05). There was increased expression of phosphorylated protein kinase C alpha in the uncontrolled hypertension group after cardiopulmonary bypass compared with before cardiopulmonary bypass and increased phosphorylated extracellular signal-regulated kinase 1/2 in the uncontrolled hypertension compared with the no hy-pertension group after cardiopulmonary bypass (P < .05). Conclusions: Uncontrolled hypertension is associated with increased coronary myogenic tone and vasoconstrictive response to phenylephrine that persists after cardioplegia and cardiopulmonary bypass. (J Thorac Cardiovasc Surg 2023;165:e256-67)

Automated summary

This study investigates the effects of cardioplegia and cardiopulmonary bypass on coronary vaso-motor tone, as well as the impact of hypertension history. It found that uncontrolled hypertension is associated with increased coronary myogenic tone and enhanced vasoconstrictive response to phenylephrine, which persists after cardioplegia and cardiopulmonary bypass. There were no significant differences between patients with no hypertension and well-controlled hypertension.