Key result
In a canine model, resting contrast defect correlated with infarct size without residual stenosis (r=0.93) and with risk area when a ≥50% residual stenosis was present (r=0.88).
Why the study?
Does intermittent harmonic imaging with intravenous microbubbles differentiate viable ischemic myocardium from infarcted myocardium following coronary reperfusion with or without residual stenosis?
Does intermittent harmonic imaging with intravenous microbubbles differentiate viable ischemic myocardium from infarcted myocardium following coronary reperfusion with or without residual stenosis?
Effect estimate: r = 0.93
The myocardial contrast defect observed with intermittent harmonic imaging and intravenous ultrasound contrast is affected by both infarct size and the presence of a significant residual stenosis.
May refine contrast echo assessment of infarct vs risk area; leaves open human validation before clinical use.
Intermittent harmonic imaging following intravenously injected perfluorocarbon-containing microbubbles can detect myocardial perfusion abnormalities caused by ischemia. It is unknown whether this technique can differentiate viable, ischemic myocardium from infarcted myocardium immediately following coronary reperfusion. The objective of this paper was to determine whether intermittent harmonic imaging with intravenous microbubbles could define myocardial perfusion abnormalities following reperfusion. In 26 dogs, a prolonged total coronary occlusion (mean occlusion time 2.1 +/- 0.4 hours) was followed by coronary reperfusion. Wall thickening (WT) and peak myocardial video intensity (PMVI) within and outside the risk area (PMVI ratio) were measured following intravenous perfluorocarbon microbubbles under resting conditions and during a 5 µg/kg per minute dobutamine [low dose dobutamine (LDD)] infusion in the presence and absence of a >/= 50% diameter stenosis in the reperfused vessel. Infarct size was determined postmortem. The resting contrast defect in all dogs correlated closely (r = 0.93) with infarct size when no residual stenosis was present but correlated more closely with risk area (r = 0.88) when a >/= 50% diameter residual stenosis was present. In dogs with infarction involving > 50% of the risk area, the PMVI ratio was lower under resting conditions (0.51 +/- 0.27) than in dogs with no or partial infarction when no residual stenosis was present. However, in dogs with no or partial infarction, the PMVI ratio fell significantly when a >/= 50% diameter stenosis was present, both under resting conditions and during LDD. We conclude that the myocardial contrast defect observed with intermittent harmonic imaging and intravenous ultrasound contrast is affected by both the infarct size and the presence of a significant residual stenosis.
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Porter et al. (1999) studied Myocardial infarction and coronary reperfusion (n=26). Intermittent harmonic imaging with intravenous perfluorocarbon microbubbles vs. Absence of residual stenosis was evaluated on Correlation of resting contrast defect with infarct size or risk area (r = 0.93). In a canine model, resting contrast defect correlated with infarct size without residual stenosis (r=0.93) and with risk area when a ≥50% residual stenosis was present (r=0.88).
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