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Increased myocardial microvascular utilisation and flow during atrial pacing
1Department of Physiology and Biophysics, Robert Wood Johnson Medical School, Piscataway, New Jersey 08854-5635.
Cardiovascular Research
|December 1, 1989
Summary
Increased heart rate boosts coronary blood flow and microvascular perfusion uniformly in rabbit hearts. This indicates that both coronary vascular and microvascular reserves are utilized during tachycardia.
Area of Science:
- Cardiovascular Physiology
- Microcirculation Research
Background:
- Understanding coronary blood flow regulation is crucial for cardiovascular health.
- The impact of increased heart rate on microvascular perfusion requires further investigation.
Purpose of the Study:
- To investigate the influence of elevated heart rate on regional coronary blood flow.
- To examine coronary vascular and microvascular responses during induced tachycardia.
Main Methods:
- Anesthetized open-chest New Zealand white rabbits were used.
- Coronary blood flow was quantified using labeled microspheres.
- Fluorescein isothiocyanate (FITC)-dextran was administered to visualize perfused microvessels.
Main Results:
- Increased heart rate significantly elevated coronary blood flow.
- The subendocardial/subepicardial flow ratio remained unchanged.
- Perfusion of capillaries and arterioles increased uniformly across the left ventricular wall.
Conclusions:
- Enhanced heart rate increases coronary blood flow and microvessel perfusion uniformly.
- Both coronary vascular and microvascular reserves are activated during tachycardia in the rabbit heart.