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[Possibilities of ACE inhibitor therapy in acute myocardial ischemia]
Insights
Angiotensin-converting enzyme (ACE) inhibitors improve coronary blood flow and myocardial function during ischemia. These drugs may also delay infarct development and offer antiarrhythmic benefits in acute myocardial infarction.
Area of Science:
- Cardiovascular Pharmacology
- Myocardial Ischemia Pathophysiology
Context:
- Acute myocardial ischemia involves increased cardiac workload or coronary occlusion, leading to arrhythmias and impaired heart muscle function.
- Existing treatments aim to preserve coronary blood flow, myocardial function, and prevent arrhythmias.
Purpose:
- To investigate the effects of ACE inhibitors on coronary blood flow and myocardial function during ischemia.
- To explore potential mechanisms, including bradykinin potentiation and neurotensin interactions.
Summary:
- ACE inhibitors and angiotensin-II-receptor blockers enhance coronary blood flow during myocardial ischemia.
- ACE inhibitors may delay infarct development, improve ischemic myocardium function, and potentiate coronary dilation.
- Clinical studies show beneficial hemodynamic and antiarrhythmic effects in acute myocardial infarction patients.
Impact:
- ACE inhibitors demonstrate potential as a therapeutic strategy for managing acute myocardial ischemia.
- Further research is needed to clarify their role in preventing non-ischemic myocardium dilatation and exercise-induced angina.
Abstract:
Acute myocardial ischemia results from an increased cardiac workload in presence of a critical coronary stenosis (demand ischemia), coronary occlusion (supply ischemia) or a combination of both. It is complicated by cardiac arrhythmias and deterioration of function of ischemic myocardium and results in an increased load and dilatation of non-ischemic myocardium. Cardiac protection in acute myocardial ischemia can be related to preservation of coronary blood flow, function of ischemic and non-ischemic myocardium or prevention of cardiac arrhythmias. In control animals and humans, ACE-inhibitors have no major effect on coronary blood flow. Myocardial ischemia raises plasma-renin-activity, angiotensin I-conversion by passage through coronary circulation, and plasma-angiotensin-II-concentrations. ACE-inhibitors and angiotensin-II-receptor blockers increase coronary blood flow during myocardial ischemia. Other mechanisms (bradykinin potentiation) may be involved. We found a potentiation of the coronary dilatory effect of the neuropeptide neurotensin (which is probably mediated by prostaglandins) by ACE-inhibitor. ACE-inhibitor may delay infarct development in animal experiments and improve function of ischemic myocardium. The importance of early dilatation of non-ischemic myocardium is unknown and it is unclear whether it may be prevented by an ACE-inhibitor as was shown for late dilatation. Studies on the effect of ACE-inhibitors in exercise-induced angina pectoris are controversial. An antiischemic and coronary dilatory effect has been shown by invasive studies in patients. A preliminary study in unstable angina pectoris was positive. Beneficial hemodynamic and antiarrhythmic effects (as well as excessive hypotension, however) have been shown in patients with acute myocardial infarction.