This Article Full Text Full Text (PDF) All Versions of this Article: 109/19/2269    most recent 01.CIR.0000128669.99355.CBv1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Fearon, W. F. Articles by Yock, P. G. Search for Related Content PubMed PubMed Citation Articles by Fearon, W. F. Articles by Yock, P. G. Pubmed/NCBI databases Compound via MeSH Substance via MeSH Hazardous Substances DB PAPAVERINE HYDROCHLORIDE Related Collections Coronary imaging: angiography/ultrasound/Doppler/CC Coronary circulation

(Circulation. 2004;109:2269-2272.)
© 2004 American Heart Association, Inc.

Brief Rapid Communications

Microvascular Resistance Is Not Influenced by Epicardial Coronary Artery Stenosis Severity

Experimental Validation

William F. Fearon, MD; Wilbert Aarnoudse, MD; Nico H.J. Pijls, MD, PhD; Bernard De Bruyne, MD, PhD; Leora B. Balsam, MD; David T. Cooke, MD; Robert C. Robbins, MD; Peter J. Fitzgerald, MD, PhD; Alan C. Yeung, MD; Paul G. Yock, MD

From the Divisions of Cardiovascular Medicine (W.F.F., P.J.F., A.C.Y., P.G.Y.) and Cardiothoracic Surgery (L.B.B., D.T.C., R.C.R.), Stanford University Medical Center, Stanford, Calif; Department of Cardiology, Catharina Hospital, and Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, Netherlands (W.A., N.H.J.P.); and Cardiovascular Center, Aalst, Belgium (B.D.B.).

Correspondence to William F. Fearon, MD, 300 Pasteur Dr, Stanford, CA 94305-5637. E-mail wfearon{at}stanford.edu

Received January 16, 2004; de novo received February 19, 2004; revision received March 23, 2004; accepted March 24, 2004.

Background— The effect of epicardial artery stenosis on myocardial microvascular resistance remains controversial. Recruitable collateral flow, which may affect resistance, was not incorporated into previous measurements.

Methods and Results— In an open-chest pig model, distal coronary pressure was measured with a pressure wire, and the apparent minimal microvascular resistance was calculated during peak hyperemia as pressure divided by flow, measured either with a flow probe around the coronary artery (R_{micro app}) or with a novel thermodilution technique (apparent index of microcirculatory resistance [IMR_app]). These apparent resistances were compared with the actual R_micro and IMR after the coronary wedge pressure and collateral flow were incorporated into the calculation. Measurements were made at baseline (no stenosis) and after creation of moderate and severe epicardial artery stenoses. In 6 pigs, 189 measurements of R_micro and IMR were made under the various epicardial artery conditions. Without consideration of collateral flow, R_{micro app} (0.43±0.12 to 0.46±0.10 to 0.51±0.11 mm Hg/mL per minute) and IMR_app (14±4 to 17±7 to 20±10 U) increased progressively and significantly with increasing epicardial artery stenosis (P<0.001 for both). With the incorporation of collateral flow, neither R_micro nor IMR increased as a result of increasing epicardial artery stenosis.

Conclusions— After collateral flow is taken into account, the minimum achievable microvascular resistance is not affected by increasing epicardial artery stenosis.

Key Words: microcirculation • coronary disease

This article has been cited by other articles:

				W. F. Fearon, M. Shah, M. Ng, T. Brinton, A. Wilson, J. A. Tremmel, I. Schnittger, D. P. Lee, R. H. Vagelos, P. J. Fitzgerald, et al. Predictive value of the index of microcirculatory resistance in patients with ST-segment elevation myocardial infarction. J. Am. Coll. Cardiol., February 5, 2008; 51(5): 560 - 565. [Abstract] [Full Text] [PDF]

				W. Aarnoudse, M. van't Veer, N. H.J. Pijls, J. ter Woorst, S. Vercauteren, P. Tonino, M. Geven, M. Rutten, E. van Hagen, B. de Bruyne, et al. Direct Volumetric Blood Flow Measurement in Coronary Arteries by Thermodilution J. Am. Coll. Cardiol., December 11, 2007; 50(24): 2294 - 2304. [Abstract] [Full Text] [PDF]

				M. K.C. Ng, A. C. Yeung, and W. F. Fearon Invasive Assessment of the Coronary Microcirculation: Superior Reproducibility and Less Hemodynamic Dependence of Index of Microcirculatory Resistance Compared With Coronary Flow Reserve Circulation, May 2, 2006; 113(17): 2054 - 2061. [Abstract] [Full Text] [PDF]

				J. A.E. Spaan, J. J. Piek, J. I.E. Hoffman, and M. Siebes Physiological Basis of Clinically Used Coronary Hemodynamic Indices Circulation, January 24, 2006; 113(3): 446 - 455. [Abstract] [Full Text] [PDF]