A 45-year-old man with stable angina is prescribed sublingual nitroglycerin for acute attacks. Which mechanism explains its anti-ischemic effect?
- A Reduction of preload via systemic venodilation decreasing myocardial oxygen demand ✓
- B Coronary artery vasodilation increasing oxygen delivery
- C Negative chronotropic effect reducing heart rate
- D Inhibition of platelet aggregation at the site of plaque rupture
Correct answer: A. Reduction of preload via systemic venodilation decreasing myocardial oxygen demand
Explanation
Nitroglycerin primarily dilates systemic veins (venodilation), reducing preload and ventricular wall tension, which is the major determinant of myocardial oxygen demand. This preload reduction is the principal anti-ischemic mechanism. It also dilates epicardary coronary arteries but does not reduce heart rate or inhibit platelets acutely.
Reference: Goodman and Gilman's The Pharmacological Basis of Therapeutics, 14th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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