Microvascular response to metabolic and pressure challenge in the human coronary circulation

de Marchi, Stefano F.; Glökler, Steffen; Rimoldi, Stefano F.; Rölli, Patrizia; Steck, Hélène; Seiler, Christian (2011). Microvascular response to metabolic and pressure challenge in the human coronary circulation. American journal of physiology - heart and circulatory physiology, 301(2), H434-H441. American Physiological Society 10.1152/ajpheart.01283.2010

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In vivo observations of microcirculatory behavior during autoregulation and adaptation to varying myocardial oxygen demand are scarce in the human coronary system. This study assessed microvascular reactions to controlled metabolic and pressure provocation [bicycle exercise and external counterpulsation (ECP)]. In 20 healthy subjects, quantitative myocardial contrast echocardiography and arterial applanation tonometry were performed during increasing ECP levels, as well as before and during bicycle exercise. Myocardial blood flow (MBF; ml·min(-1)·g(-1)), the relative blood volume (rBV; ml/ml), the coronary vascular resistance index (CVRI; dyn·s·cm(-5)/g), the pressure-work index (PWI), and the pressure-rate product (mmHg/min) were assessed. MBF remained unchanged during ECP (1.08 ± 0.44 at baseline to 0.92 ± 0.38 at high-level ECP). Bicycle exercise led to an increase in MBF from 1.03 ± 0.39 to 3.42 ± 1.11 (P < 0.001). The rBV remained unchanged during ECP, whereas it increased under exercise from 0.13 ± 0.033 to 0.22 ± 0.07 (P < 0.001). The CVRI showed a marked increase under ECP from 7.40 ± 3.38 to 11.05 ± 5.43 and significantly dropped under exercise from 7.40 ± 2.78 to 2.21 ± 0.87 (both P < 0.001). There was a significant correlation between PWI and MBF in the pooled exercise data (slope: +0.162). During ECP, the relationship remained similar (slope: +0.153). Whereas physical exercise decreases coronary vascular resistance and induces considerable functional capillary recruitment, diastolic pressure transients up to 140 mmHg trigger arteriolar vasoconstriction, keeping MBF and functional capillary density constant. Demand-supply matching was maintained over the entire ECP pressure range.

Item Type:	Journal Article (Original Article)
Division/Institute:	04 Faculty of Medicine > Department of Cardiovascular Disorders (DHGE) > Clinic of Cardiology 04 Faculty of Medicine > Service Sector > Institute of Legal Medicine > Forensic Medicine
UniBE Contributor:	De Marchi, Stefano, Glökler, Steffen, Rimoldi, Stefano, Rölli, Patrizia, Steck, Hélène, Seiler, Christian
Subjects:	600 Technology > 610 Medicine & health
ISSN:	0363-6135
Publisher:	American Physiological Society
Language:	English
Submitter:	Stefano de Marchi
Date Deposited:	25 Apr 2014 11:06
Last Modified:	02 Mar 2023 23:23
Publisher DOI:	10.1152/ajpheart.01283.2010
PubMed ID:	21572019
URI:	https://boris.unibe.ch/id/eprint/40264