Hemodynamic Effects Of Remote Ischemic Preconditioning On The Coronary Perfusion Pressure And Coronary Collateral Blood Flow In Patients With Coronary Heart Disease

Coronary heart disease?CHD?is one of the most common cause of death in the world.Although significant progress has been made in the prevention and treatment of coronary heart disease,the mortality caused by coronary heart disease in China is still increasing year by year.Reperfusion therapy including percutaneous coronary intervention?PCI?,thrombolytic therapy and coronary artery bypass surgery is still the main treatment.After decades of development,these treatment methods can effectively recirculate infarct related vessels,significantly reduce infarct size and mortality,improve life treatment and prognosis.However,reperfusion therapy may also induce ischemia-reperfusion injury while reconstructing myocardial blood flow.Ischemia-reperfusion injury will lead to damaged vascular endothelial function,swollen and necrotic myocardial cells and obstructive coronary microcirculation,finally exacerbate myocardial insufficiency and increase infarct size.Ischemic preconditioning?IPC?,being brief periods of ischemia preceding long-lasting ischemia,can reduce the susceptibility of myocardium and vascular endothelium for ischemia-reperfusion?IR?injury,and it can also reduce infarct size in CHD.Remote ischemic precondition?RIPC?,induced by several episodes of brief ischemia and reperfusion at a distance,can avoid or relieve IR injury to protect vascular endothelial function and reduce infarct size.Many clinical studies have found that remote ischemic preconditioning can reduce myocardial damage related to cardiac surgery,reduce the area of myocardial infarction,and improve the prognosis of patients with CHD.However,the exact effect is still controversial.Especially in diabetic patients,the protective effect of ischemic preconditioning is weaker than that of non-diabetic patients due to some factors such as poor collateral circulation,impaired endothelial function,insulin resistance and hypoglycemic agents.However,the specific mechanism of action is still lack of research.Endothelial dysfunction and poor collateral circulation development in diabetic patients are bound to affect the patients'coronary hemodynamics,however,little such study have been carried out.So,the present study aimed to 1)investigate hemodynamic effects of RIPC on the coronary perfusion pressure and coronary collateral blood flow in CHD;2)investigate the myocardial protection of RIPC and hemodynamic effects of RIPC in the patients with type 2 diabetes receiving PCI.Part I The acute hemodynamic effects of remote ischemic preconditioning?RIPC?on the coronary perfusion pressure and coronary collateral blood flow.Background:To assess the acute hemodynamic effects of remote ischemic preconditioning?RIPC?on the coronary perfusion pressure and coronary collateral blood flow.Mathods:A total of 17 patients with coronary heart disease of one or two-vessel severe?70%-85%?stenosis confirmed by angiography were enrolled into this study.They were randomly divided into the RIPC group?9 patients?and the control group?8patients?.And,for these patients,distal pressure of coronary artery stenosis before balloon dilation(non-occlusive pressure,P_n-occl)and distal coronary artery occlusive pressure(P_occl)during balloon dilation occlusion were measured in all patients.The patients in the RIPC group induced by three cycles of lower limb ischemia-reperfusion preconditioning?5 minutes inflations of a blood pressure cuff,followed by 5 minutes reperfusion?after the first measure.For controls,the cuff was not inflated.After this processing,P_n-occl and P_occl were measured again in each patient.Result:There were no significant differences in angiographic characteristics between two groups?All P>0.05?.The troponin I?TNI?levels after percutaneous coronary intervention?PCI?were lower in the RIPC groups than those in controls?P=0.004?.For the RIPC group,mean P_n-occl,and P_occl significantly increased after RIPC,compared to those before RIPC?72.78±10.10 mmHg vs.79.67±9.79mmHg,P=0.002,20.89±8.61mm Hg vs.26.78±10.73mmHg,P=0.001,respectively?.Conclusions:The RIPC can improve distal coronary perfusion pressure,rapidly increase distal coronary occlusive pressure thereby improving the coronary collateral blood flow.Part II Effects of RIPC on myocardial protection and collateral circulation in patients with coronary heart disease complicated with type 2 diabetes mellitusBackground:To investigate the myocardial protection of RIPC and hemodynamic effects of RIPC in the patients with type 2 diabetes receiving PCI.Mathods:A total of 49 patients with coronary heart disease and type 2 diabetes receiving planned PCI were enrolled into this study.They were randomly divided into the RIPC group?29 patients?and control group?20 patients?.And,for these patients,distal pressure of coronary artery stenosis before balloon dilation(non-occlusive pressure,P_n-occl)and distal coronary artery occlusive pressure(P_occl)during balloon dilation occlusion were measured in all patients.The patients in the RIPC group induced by three cycles of lower limb ischemia-reperfusion preconditioning?5 minutes inflations of a blood pressure cuff,followed by 5 minutes reperfusion?one hour before PCI.For controls,the cuff was not inflated.At the beginning of and after PCI 24 hours,Troponin I and CRP were measured again in each patient.Myocardial reperfusion were assessed by myocardial blush grade and TIMI.Collateral flow index and modified collateral flow index were calculated after the procedure.Follow-up was conducted for6 months to assess the clinical end point of major adverse cardiovascular events?MACCE?.Result:There were no significant differences in angiographic characteristics between two groups?All P>0.05?except body mass index?P=0.027?.There were no significant differences in P_ao and P_n-occl between control and RIPC group?89.9±14.3 vs93.9±12.8,P=0.310;71.6±10.0 vs 77.4±11.2,P=0.069,respectively?,and significant differences in P_occl?17.0±3.1 vs 21.1±3.9,P<0.001?,CFI?19.1±3.3 vs 23.0±5.7,P=0.009?and CFIm?0.239±0.044 vs 0.281±0.077,P=0.036?.CFIm presented a good correlativity with CFI.The patients with TNI levels rising more than 3 times baseline after PCI in the RIPC group were less than those in control?10 vs 5,P=0.035?.CRP and incidence of MACCE were no significant differences in two groups.Conclusions:RIPC can provide cardioprotection on the patients with coronary heart disease and type 2 diabetes undergoing PCI and reduce myocardial injury associated with PCI.RIPC can improve coronary collateral flow by increasing intra-coronary P_occlccl and CFI.CFIm can be used to assess coronary collateral flow for good correlation with CFI.