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Reduced coronary and inotropic reserves with coronary microembolization
Andreas Skyschally1, Rainer Schulz, Raimund Erbel
1Abteilungen für Pathophysiologie, Zentrum für Innere Medizin, Universitätsklinikum Essen, 45122 Essen, Germany.
Insights
Coronary microembolization impairs heart muscle function and reduces the heart's ability to increase blood flow and contractility. This study shows reduced coronary and inotropic reserves following microembolization.
Area of Science:
- Cardiovascular Physiology
- Myocardial Microcirculation
- Cardiac Function
Background:
- Microembolized myocardium exhibits a perfusion-contraction mismatch.
- Reduced contractile function occurs despite unchanged or elevated blood flow.
Purpose of the Study:
- To investigate the impact of microembolization on coronary and inotropic reserves.
- To quantify the functional consequences of coronary microembolization.
Main Methods:
- Anesthetized dogs underwent coronary microembolization using microspheres.
- Coronary blood flow (CBF), regional blood flow (RBF), and systolic wall thickening were measured.
- Coronary reserve was assessed using adenosine infusion and reactive hyperemia; inotropic reserve was evaluated with dobutamine.
Main Results:
- Microembolization significantly reduced systolic wall thickening by 50%.
- Coronary and regional blood flow remained unchanged post-embolization.
- Both coronary reserve (adenosine, reactive hyperemia) and inotropic reserve (dobutamine) were significantly blunted.
Conclusions:
- Coronary microembolization leads to a significant reduction in coronary reserve.
- Inotropic reserve is also diminished following coronary microembolization.
- These findings highlight the functional impairment of the myocardium after microembolic events.
Abstract:
Microembolized myocardium is characterized by perfusion-contraction mismatch with reduced contractile function and unchanged or even elevated blood flow. The present study investigated the consequences of microembolization on coronary and inotropic reserves. In eight anesthetized dogs, left circumflex coronary blood flow (CBF), regional blood flow (RBF), and posterior systolic wall thickening were measured. Repetitive injection of 42-microm microspheres into the left circumflex coronary artery decreased systolic wall thickening by 50% (17.2 +/- 2.4% vs. 8.0 +/- 1.4%; means +/- SD). Coronary reserve was determined by either intracoronary infusion of adenosine (n = 4) or the reactive hyperemia response following 15 s of coronary occlusion (n = 4); inotropic reserve was recruited by intracoronary infusion of dobutamine. The amount of injected microspheres was 158,000 +/- 48,000. CBF (45.5 +/- 16.5 vs. 47.8 +/- 14.4 ml/min) and RBF (1.15 +/- 0.18 vs. 1.33 +/- 0.39 ml x min(-1) x g(-1)) remained unchanged. Coronary reserve in response to intracoronary infusion of adenosine (410 +/- 94% vs. 290 +/- 77%; P < 0.05) and reactive hyperemia repayment (360 +/- 174% vs. 155 +/- 66%; P < 0.05) were blunted after microembolization. Inotropic reserve, i.e., the increment in systolic wall thickening with dobutamine, was decreased from 12.4 +/- 3.9% to 8.0 +/- 3.3% (P < 0.05). We conclude that coronary microembolization reduces coronary and inotropic reserves.