CORRESPONDENCE: LETTER TO THE EDITOR
Microvascular Angina or "Vis a Tergo"
Michael F. O'Rourke, MD, DSc* and
Wilmer W. Nichols, PhD
* St Vincent's Clinic, 438 Victoria Street, Suite 810, Darlinghurst, Sydney, NSW 2010, Australia (Email: m.orourke{at}unsw.edu.au).
Cannon (1) has drawn attention to the high prevalence of ischemia-type chest pain with normal coronary angiograms in older women in the CASS (Coronary Artery Surgery Study) and WISE (Women's Ischemia Syndrome Evaluation) studies, and referred to this as microvascular angina. He points to the need for future research on possible mechanisms. One such mechanism, which seems to have been overlooked, is the contribution of pressure and time during diastole when the left ventricle can be perfused (2). This is reduced in older women with stiffened arteries, particularly when the left ventricle is hypertrophied (3). Indeed, a decrease in diastolic duration from 33 to 27 s/min can have the same effect as an increase in coronary stenosis from 40% to 90% (4). Perhaps the continuing dilemma is created by our assumption that reduced coronary flow is always due to arterial narrowing. It seems to be appropriate to look beyond the microvascular disease that is presumed but never demonstrated.
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Footnotes
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Please note: Dr. O'Rourke is a founding director of AtCor Medical Pty Ltd., Sydney, Australia.
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References
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1. Cannon R. Microvascular angina and the continuing dilemma of chest pain with normal coronary arteries J Am Coll Cardiol 2009;54:877-885.[Abstract/Free Full Text]2. Gregg D, Fischer LC. Blood supply to the heart Handbook of Physiology. Washington, DC: Physiological Society; 1963. pp. 1517-1584. 3. O'Rourke MF. How stiffening of the aorta and elastic arteries leads to compromised coronary flow Heart 2008;94:690-691.[Free Full Text] 4. Ferro G, Duilio C, Spinelli L, Liucci GA, Mazza F, Indolfi C. Relation between diastolic perfusion time and coronary artery stenosis during stress induced coronary ischemia Circulation 1995;92:342-347.[Abstract/Free Full Text]
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