Myocardial microvascular function during acute coronary artery stenosis: Effect of hypertension and hypercholesterolaemia
Zhu XY et al. – Findings show that early exposure to the cardiovascular risk factors high-cholesterol (HC) and renovascular hypertension (HTN) protects the heart from decreases in myocardial perfusion during acute subtotal acute subtotal coronary artery obstruction (CAO). This protective effect is associated with and potentially mediated by pre-emptive development of intra-myocardial microvessels that might serve as recruitable coronary collateral arteries (CCA). Methods- Study of whether new microvessels that proliferate in early atherosclerosis are associated with myocardial protection during acute subtotal CAO
- Induction of acute left anterior descending CAO by a balloon catheter in pigs after 12 wks of HC diet, HTN, or normal controls
- Electron beam computed tomography (CT) to assess in vivo cardiac structure, myocardial perfusion, and functional response to IV adenosine and CAO
- Micro-CT to assess ex vivo intra-myocardial microvessels
- Immunoblotting for myocardial expression of growth factors
Results- Basal myocardial perfusion and microvascular permeability similar among groups
- Responses to adenosine attenuated in HC and HTN
- Significant decline in myocardial perfusion in normal pigs during acute CAO attenuated in HC and abolished in HTN
- CAO elicited increase in normal anterior wall microvascular permeability, attenuated in HC and HTN
- Microvascular spatial density significantly elevated in HC and HTN, with increased myocardial growth factor expression
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