A 62-year-old man comes to the office due to chest pain over the last 6 months. He describes pressure-like pain in the substernal area when walking fast or climbing stairs that gradually subsides when he stops. The patient does not smoke cigarettes or use illicit drugs. He has no family history of heart disease or sudden death. Physical examination shows a mid-systolic murmur at the upper sternum and slow-rising carotid pulses. After initial evaluation, cardiac catheterization is performed and reveals 30% stenosis of the mid-left anterior descending artery. A 50 mm Hg pressure gradient is seen when a catheter is passed across the aortic valve. Which of the following is the most important contributor to this patient's presenting symptoms?

Question

A 62-year-old man comes to the office due to chest pain over the last 6 months.  He describes pressure-like pain in the substernal area when walking fast or climbing stairs that gradually subsides when he stops.  The patient does not smoke cigarettes or use illicit drugs.  He has no family history of heart disease or sudden death.  Physical examination shows a mid-systolic murmur at the upper sternum and slow-rising carotid pulses.  After initial evaluation, cardiac catheterization is performed and reveals 30% stenosis of the mid-left anterior descending artery.  A 50 mm Hg pressure gradient is seen when a catheter is passed across the aortic valve.  Which of the following is the most important contributor to this patient's presenting symptoms?

Quizplus · Accepted Answer

This patient's slow-rising carotid pulses, mid-systolic murmur, and large pressure gradient across the aortic valve are consistent with severe aortic stenosis (AS). Patients can remain asymptomatic for long periods but eventually develop classic symptoms of severe AS; dyspnea is typically the first manifestation, followed by angina, presyncope or syncope, and overt heart failure. The symptoms of severe AS usually occur with exertion, as the capacity to increase stroke volume and cardiac output is limited due to the fixed left ventricular outflow obstruction (Choice D). This outflow obstruction also leads to higher chamber pressures and increased wall stress during systole and diastole. The rise in systolic wall stress increases myocardial oxygen demand while the increased diastolic wall stress reduces the coronary perfusion pressure gradient, leading to decreased myocardial perfusion. Increased left ventricular mass due to concentric hypertrophy further increases myocardial oxygen demand and contributes to anginal symptoms. (Choice A) Reduced coronary blood supply due to flow-limiting atherosclerotic plaque can cause angina in patients with obstructive coronary artery disease. Stenosis >70% is typically necessary for anginal symptoms to develop; this patient's 30% stenosis is not clinically significant. Angina often occurs in severe AS in the absence of coronary artery disease. (Choice B) Decreased coronary blood supply due to vasospasm is seen in patients with vasospastic (Prinzmetal) angina. Coronary vasospasm typically affects relatively young patients (age <50) and is not related to the angina that occurs with severe AS. (Choice C) Decreased left ventricular compliance occurs over time in AS due to the prolonged high-pressure load created by the stenotic valve. This can result in heart failure (eg, fatigue, dyspnea) due to diastolic dysfunction, but would be less likely to induce angina symptoms. Educational objective: Angina often occurs in aortic stenosis even in the absence of obstructive coronary artery disease. It results from increased myocardial oxygen demand due to an increase in left ventricular mass (ie, concentric hypertrophy) and ventricular wall stress. __________ References: Angina pectoris in patients with aortic stenosis and normal coronary arteries. Mechanisms and pathophysiological concepts. (http://www.ncbi.nlm.nih.gov/pubmed/9054747)

A 62-Year-Old Man Comes to the Office Due to Chest