Chapter 35: Nonobstructive Atherosclerotic and Nonatherosclerotic Coronary Heart Disease
Which of the following statements about normal coronary physiology and function is correct?
A. Conductance and flow in the coronary microcirculation are governed by Poiseuille’s law
B. Resistance in the conductive vessels of the precapillary coronary tree is primarily responsive to metabolic stimuli
C. Epicardial vessels represent the predominant resistance within the coronary flow circuit
The answer is A. (Hurst’s The Heart, 14th Edition, Chap. 35) Vessels branch and decrease in size, from prearterioles to arterioles to capillaries. Myocardial blood flow is regulated mostly in the coronary microcirculation, where only small changes in arteriolar diameter can result in large changes in conductance and flow as predicted by Poiseuille’s law (option A). Despite a historical focus on the epicardial coronary macrovessels, the microvessels represent the predominant resistance within the coronary flow circuit (option C), and they are innumerable in comparison to the epicardial vessels seen during invasive coronary angiography. The precapillary coronary tree consists of conductive, prearteriolar, and arteriolar vessels. Resistance in these vessel components is primarily responsive to flow, pressure, and metabolic stimuli, respectively (option B) (Figure 35-1).
FIGURE 35-1. Components of the coronary circulation. (Reproduced with permission from Maseri A. Ischemic Heart Disease. New York: Churchill Livingstone; 1995.)
A 45-year-old woman presents to clinic with chest pain and shortness of breath. She had revascularization performed in the past, but her latest angiography results did not demonstrate residual obstructive epicardial coronary stenoses. Which of the following is correct about nonobstructive coronary artery disease (CAD)?
A. Nonobstructive CAD is diagnosed much more often in men than in women
B. Results from noninvasive stress testing will likely be normal
C. The patient likely has preserved LV systolic function
D. All of the above are correct
E. None of the above are correct
The answer is C. (Hurst’s The Heart, 14th Edition, Chap. 35) A nontrivial proportion of patients with anginal symptoms and ischemia on stress testing (option B) have been noted to have an absence of fixed epicardial coronary arterial stenosis on coronary angiography.1 The condition of angina with normal angiography, more accurately termed nonobstructive CAD, is being increasingly observed and is significantly more prevalent among women than men (option A).2 In addition to those without fixed obstructive ...