Evaluation of Transmural Myocardial Perfusion by Ultra-Harmonic Myocardial Contrast Echocardiography in Reperfused Acute Myocardial Infarction

Abstract

pproximately 20-35% of angiographically successful recanalizations of the infarct-related artery in patients with acute myocardial infarction (AMI) fail to salvage ischemic myocardium because of a discrepancy between an open epicardial coronary artery and no blood flow in the damaged distal microvessels. [1][2][3][4] Regions with no-reflow show no improvement in regional function over time despite recanalization of the epicardial coronary vessels. These patients also have poorer global left ventricular (LV) systolic function, malignant ventricular arrhythmias, intractable congestive heart failure, progressive LV remodeling, cardiac rupture, and higher mortality. 2,3,5,6 Bogaert et al reported that functional recovery of viable subepicardial tissue is a mechanism of late improvement in the regional and global LV fraction after a so-called transmural myocardial infarction (MI). 7 Furthermore, our recent Circulation Journal Vol.69, September 2005 study in patients with AMI showed that assessing the microcirculation in the transmural myocardial layers by multidetector computed tomography (MDCT) predicted progressive LV remodeling and the long-term recovery in contraction. 8 Myocardial contrast echocardiography (MCE) has been proposed as a powerful modality for assessing transmural myocardial perfusion, on the basis of bedside safely, economy and repeated performance compared with other imaging modalities, because of its superior resolution in time and space without exposure to radiation. [9][10][11][12][13][14] The aims of the present study were to assess transmural myocardial perfusion by MCE and compare the results with those of MDCT and to determine whether MCE can predict the long-term recovery of LV function in patients with AMI. Methods Patient PopulationTwenty patients who had experienced their first anterior AMI during the period 2001 to 2002, had total occlusion (TIMI 0) of the proximal left anterior descending artery (LAD) and who had undergone successful balloon reperfusion therapy (TIMI 3) within 24 h of onset were investigated. The average age was 66±13 years, the male:female ratio was 17:3, the average maximum creatine kinase was 2,509±2,003 IU/ml. None showed collateral flow to the Background The transmural distribution of myocardial perfusion is important for predicting the contractile reverse of an infarcted wall in reperfused acute myocardial infarction (AMI). Evaluating transmural myocardial perfusion by myocardial contrast echocardiography (MCE) could predict the long-term recovery of left ventricular (LV) function. Methods and ResultsThe study group comprised 20 consecutive patients with a first-episode anterior AMI with total occlusion of the proximal left anterior descending artery, who underwent successful percutaneous coronary intervention within 24 h of onset. MCE was performed on the 15th day after the onset, using ultraharmonic gray-scale imaging with intermittent end-systolic triggering every 4 beats or every 6 beats. Regions of interest were placed over both the endocardial and epica...

Clinical Implications of Serial Changes in ST-Segment Elevation After Reperfusion in Patients With Anterior Acute Myocardial Infarction

“…Both patient groups had little residual ongoing ischemic myocardial injury 1 h after reperfusion, as reflected by ST resolution. 6,26 However, the myocardium has been already irreversibly damaged in the former, whereas the latter patients had a relatively large amount of viable myocardium. It is plausible that more severe, rapidly progressing myocardial damage before and during reperfusion may no longer cause ST-segment elevation after reperfusion.…”

“…[1][2][3][4][5][6] Recent studies have shown that resolution of ST-segment elevation (ST resolution) on the 12-lead electrocardiogram (ECG) after reperfusion is associated with adequate microvascular perfusion in AMI and may predict smaller infarct size, better left ventricular (LV) function, and better outcomes. 7-10 However, we previously reported that some patients have a larger infarct size, LV dysfunction, and inadequate myocardial perfusion despite ST resolution, suggesting that ST resolution does not consistently predict myocardial salvage.…”

Evaluation of myocardial viability after myocardial infarction with intravenous real-time myocardial contrast echocardiography

“…After destroying microbubbles, the rate of replenishment of microbubbles into microvessels with low MI will reflect rate of blood transfer through the tissue. The underlying basis for assessing myocardial viability with MCE is that myocardial contrast enhancement depends on an intact microcirculation [11,12] . Shimoni et al [12] showed that in the segment with normal resting function, the microcirculation was preserved; in the dysfunctional segment that improved after revascularization, the microvascular density was normal; low capillary density and significant fibrosis were seen in the dysfunctional segments also that did not recover.…”

Renin-Angiotensin System Inhibitors Can Prevent Intravenous Lipid Infusion-Induced Myocardial Microvascular Dysfunction and Leukocyte Activation

“…Electrocardiograph-triggered end-systolic intermittent myocardial microvascular images with a mechanical index of 1.1-1.2 were acquired in the apical four-chamber view at incremental pulse intervals (triggering intervals of 1, 2, 4, and 6 cardiac cycles). 17 Three or four images were captured at each pulse interval. All cardiac images were analyzed using Volumap-445 software (YD Inc., Nara, Japan).…”