Regional myocardial blood flow and coronary vascular reserve in unanesthetized ponies during pacing-induced ventricular tachycardia

Journal Article · Mon Aug 01 00:00:00 EDT 1983 · J. Surg. Res.; (United States)

DOI:https://doi.org/10.1016/0022-4804(83)90134-8· OSTI ID:5428087

Parks, C; Manohar, M; Lundeen, G

To examine the effects of tachycardia on coronary circulation, transmural distribution of myocardial blood flow (MBF, 15-micron diameter radionuclide-labeled microspheres) was studied in six healthy adult ponies at rest (heart rate . 60 +/- 7 beats . min-1), during ventricular pacing at 150 and 200 beats . min-1, as well as with ventricular pacing at 250 beats . min-1 before and during maximal coronary vasodilatation (iv adenosine infusion; 4 mumole . kg-1 . min-1). Mean aortic pressure and cardiac output were unchanged from control values with ventricular pacing. Whereas ventricular pacing at 150 and 200 beats . min-1 resulted in a progressive uniform increase in transmural MBF and well-maintained endo:epi perfusion ratio, pacing at 250 beats . min-1 did not result in a further increase in MBF compared to pacing at 200 beats . min-1 and the left ventricular (LV) subendocardial:subepicardial (endo:epi) perfusion ratio was significantly less than 1.00 (0.87 +/- 0.05). Blood flow to the LV papillary muscles and subendocardium was significantly less than that recorded at 200 beats . min-1. The LV endo:epi perfusion ratio with ventricular pacing at 250 beats . min-1 during adenosine infusion resulted in a decrease in mean aortic pressure (63% of control value) and a marked further reduction in blood flow to the LV papillary muscles as well as the LV subendocardium, while MBF increased dramatically in the LV subepicardium compared to values observed during ventricular pacing at 250 beats . min-1 alone. These data demonstrate that coronary vasomotion functions to maintain LV subendocardial blood flow in the pony myocardium at a heart rate of 200 beats . min-1, while at 250 beats . min-1 exhaustion of coronary vasodilator reserve in the deeper layers limits further increase in MBF.

• Research Organization: Department of Veterinary Biosciences, College of Veterinary Medicine, University of Illinois at Urbana-Champaign
• OSTI ID: 5428087
• Journal Information: J. Surg. Res.; (United States), Vol. 35:2
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
CORONARIES
BLOOD CIRCULATION
VASODILATION
HEART
BLOOD FLOW
BLOOD PRESSURE
HORSES
MICROSPHERES
RADIOPHARMACEUTICALS
ANIMALS
ARTERIES
BLOOD VESSELS
BODY
CARDIOVASCULAR SYSTEM
DRUGS
LABELLED COMPOUNDS
MAMMALS
ORGANS
VERTEBRATES
551001* - Physiological Systems- Tracer Techniques