Correct Answer: A

Rationale: The correct answer is A, Frank-Starling's Law. This law explains that within physiologic limits, the greater the stretch of myocardial fibers, the more forceful the ventricular contraction, leading to an increased stroke volume. Choice B, Automaticity, refers to the ability of cardiac cells to spontaneously generate electrical impulses. Choice C, Contractility, represents the intrinsic ability of the heart muscle to contract. Choice D, Excitability, refers to the ability of cardiac cells to respond to electrical stimuli.

Correct Answer: A

Rationale: The correct answer is A: Cardioversion. Cardioversion is the procedure used to restore a normal heart rhythm in patients with arrhythmias by delivering controlled electrical shocks to the heart. Choice B, Defibrillation, is incorrect because defibrillation is used to treat life-threatening arrhythmias by delivering an unsynchronized high-energy shock to the heart. Choice C, Ablation, is incorrect as it involves destroying abnormal tissue that causes arrhythmias, not necessarily restoring normal heart rhythm. Choice D, Angioplasty, is unrelated to heart rhythm restoration and is a procedure to open blocked or narrowed blood vessels.

Correct Answer: A

Rationale: Calcium channel blockers are medications that reduce high blood pressure by relaxing the blood vessels, facilitating easier blood flow through the vessels. Beta-blockers work by reducing the heart rate and the heart's workload. ACE inhibitors help relax blood vessels by blocking the production of a chemical that narrows blood vessels. Diuretics help the body get rid of excess sodium and water to lower blood pressure, but they do not directly relax blood vessels like calcium channel blockers do.

Correct Answer: A

Rationale: The correct answer is A, Headache. Nitrates commonly cause headaches as a side effect due to vasodilation. Flushing, dizziness, and nausea are less common side effects associated with nitrates. Flushing is more related to the dilation of blood vessels closer to the skin's surface, dizziness could occur but is not as common as headaches, and nausea is a less typical side effect of nitrates.

Correct Answer: A

Rationale: The correct answer is Cor pulmonale, a condition where the right ventricle of the heart fails due to increased pressure in the lungs, commonly caused by chronic lung diseases like COPD. Pulmonary embolism (choice B) is a blockage in one of the pulmonary arteries in the lungs, usually caused by a blood clot. Aortic stenosis (choice C) is a narrowing of the aortic valve opening that restricts blood flow from the left ventricle to the aorta. Hypertrophic cardiomyopathy (choice D) is a genetic condition where the heart muscle becomes abnormally thick, making it harder for the heart to pump blood.