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TELECONFRENCES
2004
The Changing Left Ventricle

2003
Aortic Valve Disease: New Dimensions in Evaluation and Management

2002
Heart Failure: Echo's Role in and Emerging Health Crisis

2001
Chest Pain in Children & Adults: The Role of Echo

2000
Mitral Regurgitation: New Concept

1998
The Falling Left Ventricle: Diastolic & Systolic Function

1997
Changing the Outcome of Coronary Artery Disease
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Chest Pain in Children and Adults

Mitral Regurgitation: New Concepts

Diastolic and Systolic Function

Changing the Outcome of CAD

BROADCAST SUPPLEMENTS
2000 MV
2001 Chest Pain
2002 Heart Failure



Ischemic Heart Disease

The potential value of echocardiography is ischemic heart disease lies in two areas: assessment of left ventricular function and diagnosis of complications that arise as sequelae of infarction.

Unfortunately, many patients with ischemic heart disease are overweight or heavy smokers, and have large `barrel' chests with hyperinflated lungs. These factors make complete echocardiographic visualization of the left ventricle difficult. Even a limited examination is at times impossible in some patients. Such limitations must be borne in mind when assessing the potential clinical value of an echocardiographic study.

Fig. 48

Left ventricular wall motion characteristics are altered by transmural myocardial infarction. The changes are usually regional and may be detected by echocardiography provided that the ultrasound beam traverses the affected area and that image quality is satisfactory.

 

 

Fig. 49

(Fig. 48) demonstrates an akinetic septum resulting from an anteroseptal infarction while
(Fig. 49) shows akinesis of the posterior wall.

 

 

 

 

Fig. 50

Two-dimensional echocardiography is usually superior for this purpose because its wider field of view provides the ability to locate and determine the extent of the infarcted myocardium. Cases of extreme systolic wall thinning and/or dyskinesia are readily apparent from inspection of sequential two-dimensional echocardiographic frames. (Fig. 50) shows extensive thinning and akinesis of the septum from a patient with a massive anteroseptal infarction.

Fig. 51

Usually, such wall motion abnormalities are best evaluated by comparison of the diastolic and systolic images. (Fig. 51) shows paired short axis views from a patient with normal wall motion characteristics. Note the symmetry of the ventricle in both diastole and systole.

Fig. 52

It must be kept in mind that the heart moves through the interrogating plane as it cycles through diastole and systole. This gross movement, even in normal individuals causes different regions of the myocardium to be interrogated in systole and in diastole and may lead to spurious interpretive errors (Fig. 52).

In addition, incorrect orientation of the short axis plane such that the ventricle appears eliptical rather than circular will cause any motion of the posteroseptal and lateral walls to appear exaggerated. Another common error in interpretation of wall motion abnormalities concerns the relative movements of the endocardium, epicardium and pericardium. In normal individuals, the movement of the epicardium and/or pericardium is much less than the endocardium. In patients with marginal image quality where only a portion of the endocardium is identified, the interpreter should not compare areas of endocardial movement to areas of movement where only the pericardium is visualized. This leads to the incorrect interpretation that asynergy is present in the poorly visualized segment.

Fig. 53

If images of suitable quality are available, it is possible to analyze ventricular wall motion on a regional basis and to apply semiquantitative or quantitative descriptors to each segment of the myocardium. A number of simple and complex formats for performing such assessment have been proposed. (Fig. 53) illustrates the most simplistic format where the ventricle is divided into five segments: septal wall, anterior wall, posterior wall, inferior wall and apex. Using all the views possible, most wall segments can be located echocardiographically, albeit some with difficulty. Wall motion is then scored as normal, hypokinetic, akinetic or dyskinetic in each of the five segments.

Fig. 54

The most reliable interpretation of these changes comes from assessment of the moving image rather than still-frames. An inferior area of hypokinesis is seen in the short axis of the left ventricle shown in (Fig. 54).

Animal studies have indicated that wall motion abnormalities will occur almost instantaneously following coronary ligation. The utility of such an examination depends upon the clinical questions posed. For example, echocardiography may be used to assess the extent of damage in a patient with classic EKG and enzyme changes of a myocardial infarction. In patients without classical changes, echocardiographic assessment may be helpful in influencing the clinical decision making process by detecting the presence or absence of wall motion changes.

Recent advances in computer technology have allowed for the digitization of a single cardiac cycle and for continuous loop replay to assist the interpreter in detecting wall motion abnormalities. This technology also allows for the placement of similar views side-by-side on the same screen before and after exercise. Since only one beat is required, it can usually be captured despite the patient's heavy breathing following peak exercise. Such features in instrumentation are referred to as "cine- loops".

Thus, echocardiography is now growing in use for the exercise evaluation of patients with suspected coronary artery disease using protocols roughly equivalent to those used for radionuclide evaluations. When image quality is adequate, echocardiography serves as a cheaper alternative that does not require the use of isotopes. Because no ionizing radiation is involved, patients may be evaluated more often depending upon the clinical situation involved. Multiple recent studies have indicated that this approach is as reliable as other methods and serves as a suitable alternative.

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