Perfusion-contraction mismatch with coronary microvascular obstruction: role of inflammation

A close relationship exists between regional myocardial blood flow (RMBF) and function during acute coronary inflow restriction (perfusion-contraction matching). However, the relationship of flow and function during coronary microvascular obstruction is unknown. In 12 anesthetized dogs, the left circumflex coronary artery was perfused from an extracorporeal circuit. After control measurements, 3,000 microspheres (42 micrometer diameter) per milliliter per minute inflow were injected to cause a microembolism (ME, n = 6). With unchanged systemic hemodynamics and RMBF, posterior systolic wall thickening (PWT) decreased from 19.8 +/- 1.9% SD at control to 13.3 +/- 4.0, 10.3 +/- 3.8, and 6.9 +/- 4.7% (P < 0.05 vs. control) at 1, 4, and 8 h, respectively. For comparison, inflow was progressively reduced to match PWT to that of the ME group at 1, 4, and 8 h (stenosis, STE, n = 6). RMBF in the STE group was reduced in proportion to PWT. Infarct size was not different among groups (6.5 +/- 4.5 vs. 3.4 +/- 3.2%). However, the number of leukocytes infiltrating the area at risk was significantly greater in the ME group than in the STE group. Coronary microembolization results in perfusion-contraction mismatch and is associated with an inflammatory response.