Echocardiographic findings in experimental myocardial infarction of the posterior lift ventricular wall

Can left main or proximal left anterior descending coronary artery disease be assessed by non-invasive means?

One hundred consecutive patients with angina pectoris referred for coronary arteriography were studied prospectively for non-invasive assessment of left main (LMCA) or proximal left anterior descending coronary artery (proximal LAD) disease. Evaluation of echocardiographic interventricular septal motion, history and exercise test response could not identify the patients with these specific lesions. It is concluded that LMCA and proximal LAD disease still remain largely unpredictable by non-invasive means.

Left ventricular excursions and velocities during coronary arterial ligation. Effects of nitroglycerin infusion in an experimental model

To determine the effects of intravenous nitroglycerin on the velocities and excursions of the acutely ischemic myocardium, 20 open-chest dogs were studied by use of ultrasound. In 10 dogs with acute septal ischemia, the posterior wall excursion during contraction (B-C excursion), the mean systolic posterior wall velocity, and the posterior wall excursion remained unaltered. Nitroglycerin, however, increased all these parameters (P less than 0.01). In 10 dogs with acute posterior wall ischemia the B-C excursion (aneurysmal bulging) increased (P less than 0.01), but the mean systolic posterior wall velocity and posterior wall excursion decreased (P less than 0.01). Nitroglycerin increased even more the aneurysmal bulging (P less than 0.01) and the other parameters (P less than 0.01). Increased regional blood flow, reduced afterload, and mechanical pulling of the ischemic myocardium seem to be a possible mechanism. The measurements were obtained using the recently described method of the specific points.

Detection of ischemic wall dysfunction: comparison between M-mode echocardiography and sonomicrometry

The quantification of regional ventricular function by M-mode echocardiography was compared to that by sonomicrometry in 10 closed-chest, sedated swine during temporary occlusions of the left circumflex coronary artery. Wall thickening during systole (%WT) was calculated to quantitate regional myocardial function, and percentage of fractional shortening (%FS) was calculated from both sonomicrometer tracings and M-mode echocardiograms. Ventricular dimensions at end diastole and end systole were also compared before and after 2 minutes of coronary artery occlusion. Both techniques detected significant changes in wall thickness, %WT, and %FS after occlusion. Changes in %WT during coronary artery occlusion detected by M-mode echocardiography and sonomicrometry had a significant linear relationship (p less than 0.05). Discrepancy between the two techniques in the measurement of wall thickness at end diastole was attributed to the difficulty in measuring relatively small distances with M-mode echocardiograms. However, we conclude that the clinical M-mode echocardiogram is capable of detecting acute regional wall dysfunction associated with ischemia.

Detection of acute myocardial infarction in closed-chest dogs by analysis of regional two-dimensional echocardiographic gray-level distributions

We hypothesized that acute myocardial infarction could be detected in standard two-dimensional echocardiograms of closed-chest dogs by evaluating regional echo amplitude distributions using computerized image analysis. We tested this hypothesis by performing standard, 2.4 MHz two-dimensional echoes before and 2 days after circumflex coronary occlusion in seven closed-chest dogs. Control and infarcted regions of interest were studied in digitized stop-frame images. Average gray level was calculated for each region of interest, and the shape of the gray-level distribution was analyzed by calculation of skewness and kurtosis and by qualitative features of shape. Average gray level increased significantly from the pre- to postocclusion images in the infarcted regions (16.7 +/- 4.2 vs. 32.4 +/- 4.4 units, P less than 0.01), but not in the control regions (17.4 +/- 4 vs. 22.3 +/- 5.5., P = NS). Average gray level could not distinguish between infarcted and normal regions within the postocclusion images (36 +/- 5.2 vs. 33.6 +/- 5.8, P = NS). Three independent observers qualitatively evaluated histogram shape and correctly identified 7/7 MI regions (100% sensitivity) and 14/20 normal regions (70% specificity). Quantitatively, infarct regions exhibited a significant decrease in kurtosis from pre- to postocclusion images (7.1 +/- 4.0 vs. 5.2 +/- 2.9, P = NS). Within postocclusion images, infarcted regions displayed a significantly lower kurtosis than did normal regions (0.27 +/- .47 vs. 2.5 +/- 1.0, P less than .01). We conclude that acute myocardial infarction may be detected in closed-chest dogs by analyzing regional echo amplitude data from standard two-dimensional echocardiograms.

Echocardiographic detection of coronary artery disease. Detection of effects of ischemia on regional myocardial wall motion and visualization of left main coronary artery disease

M mode and cross-sectional echocardiographic studies at rest have been used to detect regional left ventricular wall motion abnormalities as a sign of hemodynamically significant coronary artery disease. These techniques have proved to be fairly specific but not highly sensitive. Detection of new regional wall motion abnormalities with cross-sectional echocardiography during exercise appeared practical in 80 percent of patients in preliminary studies; the finding of such abnormalities is highly specific for the presence of coronary artery disease and, with this approach, the sensitivity of echocardiography is improved. Thus, patients with anatomically severe coronary artery disease on angiography may not manifest an echocardiographic abnormality in regional wall motion even during exercise. The direct noninvasive detection of the left main coronary artery in up to 90 percent of patients studied with cross-sectional echocardiography using the short axis or apical approach, or both, has been well defined. A high sensitivity and specificity of detecting anatomically severe left main coronary artery disease using the criteria of both luminal impingement and the presence of high intensity echoes have been confirmed. Further advances in imaging techniques may allow for better definition of the coronary arterial tree.

Echocardiographic determination of septal and left ventricular wall motion in the early hours of acute myocardial infarction

Interventricular septal and left ventricular posterior wall excursions and velocities were determined by M-mode echocardiography in the early hours of acute myocardial infarction in 43 patients. In the group with anterior infarction, including 24 patients, the systolic septal excursion (SSE), systolic septal velocity (SSV), diastolic septal excursion (DSE), and diastolic septal velocity(DSV) were decreased (P less than 0.001). The posterior wall excursion during isovolumetric contraction (B-C) and the mean systolic posterior wall velocity (PWVmean) were also decreased (P less than 0.02). The posterior wall excursion during ejection (PWE) was not affected significantly. In the group with inferior infarction, including 19 patients, the B-C excursion was not significantly affected, but the PWE and PWVmean were diminished (P less than 0.001). The opposing healthy interventricular septum showed an increased movement-compensatory hyperactivity. These findings indicate that the acute myocardial ischemia which grossly affects the mobility of the myocardium can be detected and determined in the early hours by M-mode echocardiography.

Improved echocardiographic evaluation of the closed-chest canine: methods and anatomic observations

This report describes an improved and convenient method of obtaining echocardiograms from the precordial surface of the closed-chest conscious dog. All major cardiac structures were identified using contrast echocardiography. Anatomic relations and the orientation of cardiac structures to the ultrasound transducer in the position of study were established by postmortem examinations. Good quality echocardiograms were obtained from nine of 11 conscious dogs. Highly significant correlations were found when comparing left ventricular systolic time intervals measured from simultaneous echo and pressure recordings. This method has advantages over other echo techniques; namely, elimination of surgical intervention, displacement of interfering lung tissue, and wider field available for study with a minimum of reverberation artifact. The ability to obtain echocardiograms from the chronic experimental dog under physiologic conditioins might provide new and improved applications of echocardiography for the evaluation of human cardiac disorders.

Prognostic value of echocardiographic evaluation of septal function in acute anteroseptal myocardial infarction

To determine the clinical usefulness of echocardiography in patients with anteroseptal myocardial infarction, echocardiograms were performed within 24 hours of admission on 40 patients with acute transmural anteroseptal myocardial infarction. Twenty-one patients had normal septal motion and septal systolic thickening, and 19 patients had abnormalities of one or both of these measurements. Of the 21 patients who had normal septal motion and thickening, only five developed congestive heart failure, none developed bundle branch block, and none died. Of the 19 patients with abnormal septal motion and/or thickening, 17 developed congestive heart failure (p less than .001), seven developed bundle branch block (p less than .001), and six died (p less than .001). Therefore, (1) electrocardiographic evidence of septal infarction does not correlate with abnormalities of the portion of septum seen on echocardiogram, and (2) patients with anteroseptal myocardial infarction and abnormalities of the septum on echocardiogram have more complications and a higher in-hospital mortality rate. These patients may have more extensive myocardial infarction predisposing to pump failure and possibly involving the conduction system.

Differentiation of posterior myocardial infarction from right ventricular hypertrophy and normal anterior loop by echocardiography

The differentiation of posterobasal myocardial infarction (PMI) from either right ventricular hypertrophy (RVH) or normal subjects displaying an anterior loop (AL) by electrocardiography (ECG) or vectorcardiography (VCG) is difficult. M-mode echocardiography (echo) via the anterior and subxiphoid methods has been helpful in defining cardiac chamber size and wall motion abnormalities. We tested whether this relatively more direct method would better separate these entities compared with the other two techniques. ECG and VCG using established criteria failed to distinguish the three conditions effectively. By echo, distinguishing characteristics were observed in each of the groups. Thus, right ventricular diastolic dimension and wall thickness were significantly increased only in the RVH group, echo dimensions and wall motion were normal in the AL group and the posterior left ventricular systolic thickening response and ejection phase indices were significantly reduced only by the subxiphoid method in the PMI group. To test the specificity of the latter finding, posterior wall motion in three infarction groups (posterior, combined posteroinferior and inferior) were examined and suggested that the target of the subxiphoid beam focuses on a more superior posterobasal left ventricular segment than the anteriorly placed transducer. Echocardiography can differentiate PMI from either RVH or AL more directly than ECG or VCG, and may be of practical clinical importance.

Evaluation of regional myocardial function in ischemic heart disease by echocardiography

Echocardiography can display motion abnormalities of acutely or chronically ischemic myocardium. In experimental studies, this permits the evaluation of the effect on regional dyskinesis of potentially therapeutic interventions. In clinical studies, the demonstration of segmental dyskinesis has been primarily useful for diagnostic purposes. As more experience is gained with the newer two-dimensional cross-sectional ultrasound techniques, it appears likely that these will afford a major advance in the diagnosis of ischemic heart disease by permitting the routine noninvasive demonstration of segmental ventricular dyskinesis and assessment of regional myocardial function.

Ventricular septal defect complicating acute myocardial infarction. Echocardiographic demonstration confirmed by angiocardiograms and surgery

The echocardiographic findings in one patient with a ventricular septal perforation as a result of an acute anteroseptal myocardial infarction are presented. Continuous echocardiographic scanning enabled us to demonstrate a septal discontinuity below the atrioventricular junction. The correct echocardiographic diagnosis was confirmed angiocardiographically. After surgical repair of the ventricular septal defect, the echocardiogram failed to reveal the septal discontinuity previously present. A search of the literature did not disclose any report of similar echocardiographic findings.

Role of echocardiography in patients with coronary artery disease

Impaired left ventricular performance, one of the hallmarks of coronary artery disease, can be detected by echocardiography in various ways. One of these approaches is the recording of abnormal wall motion. Because of the way in which the left ventricle can be examined echocardiographically, this technique has the capability of detecting regional wall abnormalities. In fact echocardiography is probably the most sensitive technique available, including even contrast ventriculography, for the detection of akinetic, hypokinetic or dyskinetic wall segments. With increasing experience it is apparent that more areas of the left ventricle can be examined echocardiographically than had previously been thought possible. Newer techniques include directing the ultrasonic beam not only through the body of the left ventricle but also toward the apical portion of the ventricle near the vicinity of the papillary muscles. In addition the true anterior left ventricular wall can be examined by moving the transducer laterally away from the left sternal border. Yet another approach utilizes a subxiphoid position for the transducer while the ultrasonic beam is directed through the medial portion of the septum and posterolateral wall of the left ventricle. M-mode scanning techniques together with recently developed cross-sectional echocardiographic instruments give great promise of improved detection of abnormalities of ventricular shape, especially the presence of aneurysms. The cross-sectional approach makes it possible to examine the left ventricular apex, an area virtually impossible to record with M-mode echocardiography. Recording of left ventricular dimensions and abnormal mitral valve motion may help in assessing overall left ventricular performance. A dilated left ventricular dimension in the vicinity of the mitral valve seems to be an ominous finding both in patients with acute myocardial infarction and in patients with chronic coronary disease being considered for possible surgery. Another echocardiographic sign of abnormal ventricular performance is altered closure of the mitral valve, which reflects a significantly elevated left ventricular diastolic pressure. These echocardiographic techniques are still in the investigational stages and are more technically difficult than the usual echocardiographic applications. However, the preliminary data are encouraging and make us hopeful that echocardiography will prove to be an important tool in the overall evaluation of the left ventricle in patients with coronary artery disease.

Echocardiography in acute myocardial infarction

Sixty-four patient with acute transmural myocardial infarction had daily echocardiograms while in the coronary care unit. Patients with previous infarction were excluded. The electrocardiographic site of infarction was anterior wall in 28, inferior wall in 33 and both anterior and inferior wall in 3 patients. Echocardiograms satisfactory for interpretation were obtained in 92 percent of cases. Abnormal left ventricular wall motion corresponding to the electrocardiographic site of infarction was seen in the echocardiogram in 84 percent of cases. Exaggerated normal motion in noninfarcted areas was seen in 30 percent. The left ventricular internal dimension correlated with clinical heart failure (P less than 0.005) and was increased in 50 percent. Abnormal mitral valve closure, which reflects increased left ventricular end-diastolic pressure, was present in 33 percent. This finding did not correlate significantly with clinical heart failure. By combining the measurements of left ventricular internal dimension and mitral valve closure, it was possible to predict hospital mortality from the echocardiograms. The results indicate that echocardiography is a useful technique in the study and management of patients with acute myocardial infarction.

Echocardiographic features of congestive cardiomyopathy compared with normal subjects and patients with coronary artery disease

Echocardiograms of ten patients with congestive cardiomyopathy were compared to those of three groups of patients: (1) 17 with no catheterization or angiographic evidence of cardiac disease; (2) 19 with 75% or greater obstruction of one or more coronary arteries (CAD); and (3) 8 with previous myocardial infarction and congestive heart failure (CAD-CHF). Echocardiographic values of interest included the left ventricular internal dimension at end-diastole/body surface area (LVIDd index), the amplitudes of the left septal echo (LSa) and posterior endocardial echo (ENa), LSa + ENa, and the maximum rate of rise of the posterior endocardial echo ([See Equation in PDF File]). Septal and posterior wall thicknesses were measured and the presence or absence of pericardial effusion and abnormal mitral valve closure were observed. All of the left ventricular measurements were significantly different when comparing the cardiomyopathy group with the normal and CAD groups. Differentiating cardiomyopathy from the CAD-CHF group was far more difficult with the only highly significant difference being the LSa + ENa ( P < 0.001). Only one cardiomyopathy patient and one CAD-CHF patient had a sum of LSa + ENa overlapping the other group.

These results are consistent with the diffuse disease usually seen in congestive cardiomyopathy and the segmental nature of coronary artery disease in which some area of the left ventricle moves well even in the presence of congestive heart failure.