Assessment of Myocardial Postreperfusion Viability by Intravenous Myocardial Contrast Echocardiography

Abstract

Background-Although defects on intracoronary myocardial contrast echocardiography (MCE) indicate loss of viability after reperfusion, opacified segments may also exhibit persistent dyssynergy. Therefore, we related the intensity and texture of opacification produced by an intravenous contrast agent to histological findings to determine the characteristics of necrotic tissue by postreperfusion MCE. Methods and Results-MCE was performed by intravenous injection of 0.15 mL/kg QW7437 in 14 dogs who underwent 3-hour coronary occlusion followed by 3-hour reperfusion. At baseline and 3 hours after reperfusion, midventricular short-axis images were digitized and segmented. Infarction fraction (IF) for each segment was determined by triphenyltetrazolium chloride stain. Of 224 segments, 140 showed no or small infarction and served as a control group. Of 84 segments with significant infarction (IFϾ30%), 52 exhibited a defect on MCE, and 32 exhibited no defect. Echo texture was quantified by computing entropy based on the co-occurrence matrix analysis of gray-level pairs within each segment. Three hours after reperfusion, average and maximal entropies in the infarct segments without opacification defects were significantly higher than control levels. Histologically, the degree of intracapillary erythrocyte stasis was less in this group than in the infarcted segments with MCE defects with similar magnitude of tissue injuries. Conclusions-Opacification defects by MCE may be present or absent in myocardium with histologically confirmed infarction. The texture of MCE from opacified but infarcted myocardium differed significantly from control segments and may assist in determination of segmental viability after reperfusion.

Relation of ultrasonic tissue characterization with integrated backscatter to contractile reserve in patients with chronic coronary artery disease

“…2,3,15,16 Methods for assessing the potentially viable myocardium include the use of postextrasystolic potentiation during left ventricular angiography, 17 the response of left ventricular contraction to an inotropic stimulus such as dobutamine, 2, 3, 15 evidence of uptake of thallium-201 in a dysfunctional region of myocardium, 3,6 positron emission tomography, 18 and intravenous myocardial contrast echocardiography (MCE). 19,20 Because of technical limitations, these methods cannot be applied in all hospitals. Compared with these methods, ultrasonic tissue characterization is simple; therefore, ultrasonic tissue characterization should be a new diagnostic modality for evaluating reversibly dysfunctional segments in patients with CAD.…”

Potential clinical applications of myocardial contrast echocardiography in evaluating myocardial perfusion in coronary artery disease

“…The early reestablishment of epicardial coronary patency after thrombolysis or angioplasty is a determining factor for the restriction of the infarct size. Most of the recent data [33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50] have been focused on STEAMI and revealed that restoration of epicardial coronary artery patency is not equivalent to restoration of nutritive tissue flow [33]. Functional and structural microvascular disturbance-low or no reflow phenomenon-despite infarct artery patency, is an important pathophysiologic phenomenon in the setting of reperfused STEAMI.…”

Segmental quantitative analysis of myocardial contrast echocardiography images using a bullseye representation

“…Echo textures was analyzed by using c ooccurrence matrices, which were constructed for each pixel in the area of interest comparing pairs of gray levels in surrounding pixels and evaluat ing related properties using second order statistics [1]. For each neighborhood the co-occurrence matrix is calculated and then the entropy of this matrix.…”

“…Considering the ability of MCE for assessing microvascular integrity, this technique may be useful for quantifying myocardial viability after sucessful reperfusion in acute myocardial infarction [1] and to estimate infarct size [2]. To quantitatively analyse the different patterns of myocardial opacification following coronary occlusion and reperfusion, in this study, we propose a method that is able to aggregate information from myocardial contrast images and tissue characterization analyzes to compose a my ocardial perfus ion and texture polar map of the left ventricle in an animal model of myocardial infarction.…”