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Evaluation of Coronary Flow Reserve After Myocardial Ischemia Reperfusion in Rats
Published on: June 28, 2019
Abnormalities of capillary microarchitecture in a rat model of coronary ischemic congestive heart failure
Jiqiu Chen1, Elisa Yaniz-Galende1, Heather J Kagan1
1Cardiovascular Research Center, Mount Sinai School of Medicine, New York, New York.
Insights
Capillary disorder, including stenosis and structural changes, significantly impacts coronary ischemic congestive heart failure (CHF). These microvascular abnormalities in the heart may reduce myocyte contractility.
Area of Science:
- Cardiovascular Research
- Heart Failure Pathophysiology
- Microcirculation Studies
Background:
- Congestive heart failure (CHF) is often associated with coronary artery disease.
- The role of microvascular dysfunction, particularly in capillaries, in CHF pathogenesis remains incompletely understood.
Purpose of the Study:
- To investigate the characteristics and functional implications of capillary disorders in a rat model of coronary ischemic congestive heart failure.
Main Methods:
- Congestive heart failure (CHF) was induced in rats via aortic banding and ischemia-reperfusion.
- Coronary vasculature was analyzed using fluorescent polymer casting and scanning electron microscopy.
- Cardiac function was assessed through echocardiography and in vivo hemodynamics.
Main Results:
- CHF hearts exhibited stenosis across all coronary artery levels.
- Increased coronary vasculature volume and capillary density (≤3 μm diameter) were observed in remote myocardium.
- Capillaries in CHF showed tortuosity, inconsistent diameters, rough surfaces, and shorter segments between bifurcations.
Conclusions:
- Coronary microvascular disorder, including capillary stenosis, structural deformation, and endothelial dysfunction, is a significant feature of ischemic congestive heart failure.
- These capillary abnormalities may contribute to reduced myocyte contractility and impaired cardiac function in CHF.
- The findings highlight the importance of addressing microcirculatory dysfunction in heart failure management.
Abstract:
The aim of the present study is to explore the role of capillary disorder in coronary ischemic congestive heart failure (CHF). CHF was induced in rats by aortic banding plus ischemia-reperfusion followed by aortic debanding. Coronary arteries were perfused with plastic polymer containing fluorescent dye. Multiple fluorescent images of casted heart sections and scanning electric microscope of coronary vessels were obtained to characterize changes in the heart. Cardiac function was assessed by echocardiography and in vivo hemodynamics. Stenosis was found in all levels of the coronary arteries in CHF. Coronary vasculature volume and capillary density in remote myocardium were significantly increased in CHF compared with control. This occurred largely in microvessels with a diameter of ≤3 μm. Capillaries in CHF had a tortuous structure, while normal capillaries were linear. Capillaries in CHF had inconsistent diameters, with assortments of narrowed and bulged segments. Their surfaces appeared rough, potentially indicating endothelial dysfunction in CHF. Segments of main capillaries between bifurcations were significantly shorter in length in CHF than in control. Transiently increasing preload by injecting 50 μl of 30% NaCl demonstrated that the CHF heart had lower functional reserve; this may be associated with congestion in coronary microcirculation. Ischemic coronary vascular disorder is not limited to the main coronary arteries, as it occurs in arterioles and capillaries. Capillary disorder in CHF included stenosis, deformed structure, proliferation, and roughened surfaces. This disorder in the coronary artery architecture may contribute to the reduction in myocyte contractility in the setting of heart failure.
