A patient of prinzmetal's angina is staed on isosorbide mononitrate. What is the mechanism of action of nitrates in this condition?: (A) Reduced cardiac contractility, (B) Increased left ventricular end diastolic volume, (C) Decreased diastolic perfusion pressure, (D) Endothelium independent coronary vasodilation
Answer is D. Prinzmetal's angina is due to spasm of main coronary aery. Treatment is by dilatation of coronary aery. Endothelium normally generates NO, but here we are giving nitrates for generation of NO. Mechanism of action of nitrates: Preload reduction >> Afterload reduction Redistribution of coronary flow in the aerial tree action may cause orable redistribution of blood flow to ischaemic areas in angina patients.