Vasodilator reserve in collateral-dependent myocardium as measured by positron emission tomography

• Published in: European heart journal 1993-03, Vol.14 (3), p.336-343
• Main Authors: MCFALLS, E. O., ARAUJO, L. I., LAMMERTSMA, A., RHODES, C. G., BLOOMFIELD, P., PUPITA, G., JONES, T., MASERI, A.
• Format: Article
• Language: English
• Subjects: Adult; Biological and medical sciences; Cardiovascular system; Case-Control Studies; collateral blood flow; Collateral Circulation - physiology; Coronary Circulation - physiology; Coronary Disease - diagnostic imaging; Coronary Disease - physiopathology; Coronary Vessels - diagnostic imaging; Coronary Vessels - physiopathology; flow reserve; Heart - diagnostic imaging; Heart - physiology; Heart - physiopathology; Hemodynamics; Humans; Investigative techniques, diagnostic techniques (general aspects); Male; Medical sciences; Middle Aged; Positron emission tomography; Radionuclide investigations; Tomography, Emission-Computed; Vasodilation - physiology
• ISSN: 0195-668X; 1522-9645
• DOI: 10.1093/eurheartj/14.3.336

Myocardial blood flow can be accurately quantitated in patients using positron emission tomography and oxygen-15 labelled water. The purpose of this study was to determine the vasodilator reserve in myocardium completely perfused by intramyocardial collateral blood flow. We hypothesized that altered relative flow reserve in such regions would correlate with the degree of ischaemia observed in these patients during exercise. The technique involves the inhalation of the positron emitting tracer C15O2 which is converted to freely diffusible H215O by the lung. With rapid dynamic scanning, arterial and regional myocardial tissue concentrations can be obtained and time activity curves generated. With a two-compartment kinetic model, myocardial blood flow can be accurately quantitated over a wide range of blood flows. Five patients with stable exertional angina and normal ventricular function studies and who had an occluded major epicardial artery which completely opacified via intramyocardial collateral blood flow were studied. Myocardial blood flow (MBF) was measured both at rest and following an infusion of intravenous dipyridamole (0.56 mg. kg−1) and the results were compared with measurements obtained from a group of eight normal volunteers. During resting conditions, MBF in the control group was 0.86±0.10ml. g−1. min−1 and in the patient group was 0.99±0.10 ml. g−1. min−1 in normally perfused myocardium (ns) and 0.86±0.14 ml. g−1. min−1 in collateral-dependent myocardium (ns). Following dipyridamole, MBF increased to 3.58±0.89 ml. g−1. min−1 in the control group and to 2.97±0.94 ml. g−1. min−1 in the normal regions of the patients (ns). In the collateralized regions of the patients, the increase was less than that observed in the control group (1.66±1.02, P