International Journal of Cardiology, 2 (1982) 61-70 Elsevier Biomedical Press

61

Regional left ventricular ejection fraction from real-time two-dimensional echocardiography ’

Azaria J.J.T. Rein, Dan Sapoznikov, Noga Lewis,

David A. Halon, Mervyn S. Gotsman and Basil S. Lewis

Department of Cardiology, Hadassah Hospital and the Hebrew Umverstty, Jerusalem, Israel

(Received 28 April 1981; second revision received 29 April 1982: accepted 21 May 1982)

Rein AJJT, Sapoznikov D, Lewis N, Halon DA, Gotsman MS, Lewis BS. Regional left ventricular ejection fraction from real-time two-dimensional echocardiography.

Int J Cardiol 1982; 2: 61-70.

We studied regional left ventricular contraction patterns and ejection fraction from real-time two-dimensional echocardiograms in 8 normal subjects, 11 patients with coronary artery disease and 2 with congestive cardiomyopathy. The ventricle was divided into 12 regions and for each region, we calculated ejection fraction using a method which integrated the incremental volumes of a series of hemicylinders constructed within that region. The data obtained were displayed graphically to provide a detailed picture of regional ventricular function. Normal subjects had a uniform regional ventricular pattern (regional ejection fraction E&74%). In patients with coronary disease, we found varying degrees of regional ventricular contraction abnormalities. In congestive cardiomyopathy global hypokinesis was present, and regional ejection fraction was reduced in all areas (ll-39%). The study showed that two-dimensional echocardiography is a useful non-invasive bedside technique which may provide detailed quantitative information relating to regional left ventricular contraction abnormalities.

Introduction

Left ventricular function studies are an integral part of the diagnosis and assessment of cardiac patients. The prognosis and treatment of the patient can

depend upon the state of ventricular performance, especially in patients who are

’ Supported by grants from the Myra Kurland Fund and the Fund for Advancement of Mankind.

Reprint requests to: Professor B.S. Lewis. Cardiology Department, Hadassah Hospital, Jerusalem, Israel.

0167-5273/82/0000-0000/$02.75 0 1982 Elsevier Biomedical Press

62

candidates for coronary artery bypass surgery or ventricular aneurysmectomy.

Angiography [l-5] and radionuclide ventriculography [6-91 provide quantitative data relating to global and regional ventricular function. We and others have

developed models to display graphically the dynamics of left ventricular wall motion

and to calculate the fractional shortening of different areas of the ventricle (regional

ejection fraction) [ 10,l 11. Real-time two-dimensional echocardiography is a simple, non-invasive technique

which has been used to study cardiac and left ventricular function. There are several

studies which show that two-dimensional echocardiography can provide measure-

ments of left ventricular volume and ejection fraction [12-141 and can identify and

quantitate the extent of areas of abnormal contraction in coronary artery disease

[ 15,161. We have extended the use of the two-dimensional echo technique to record

and analyse in detail regional ventricular wall motion and regional ventricular

ejection fraction. This paper presents detailed graphical displays of the contraction

patterns of different segments of the left ventricle in normal subjects and in patients with coronary artery disease.

Patients and Methods

Patients

We studied 21 patients who were divided into 3 groups. (1) Eight normal subjects (2 males, 6 females; age 18-38 years) who were referred to

our echocardiographic laboratory following detection of a soft systolic murmur.

Clinical examination, electrocardiogram, chest X-ray and the echocardiogram con-

firmed the diagnosis of an innocent systolic murmur. (2) Eleven patients with coronary artery disease who were referred for diagnostic

cardiac catheterization and coronary angiography (8 males, 3 females, age range

38-61 years). All patients had suffered an episode of myocardial infraction and were subsequently shown to have an area of regional ventricular asynergy by left

ventricular cineangiography.

(3) Congestive cardiomyopathy was present in 2 patients, probably related to preced- ing viral myocarditis. We compared the findings in these patients with those of

patients with coronary artery disease.

Data acquisition

We recorded the echocardiograms with an Ekosector 1 ultrasonograph (Smith- Kline Instruments) fitted with an 81” probe and a Sanyo VTC 7100 video cassette recorder. Diagnostic echocardiograms were recorded in the parasternal, apical and subxiphoid views with the patients in the left oblique or left lateral position. We

used the apical 4 chamber view in the present analysis. It was recorded in the plane of the mitral valve, with 10-20’ counterclockwise rotation of the transducer to

demonstrate the anterolateral and inferoseptal surfaces of the left ventricle but is not identical to the right anterior oblique view of a left ventricular cineangiogram. The

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view recorded was that which maximised the ventricular long axis. Biplane studies may provide closer correlations of echo and angio volumes [ 141, but construction of regional ejection fraction graphs is complicated from biplane formulae.

We included only patients who had high technical quality echocardiograms in this study. The present quality of two-dimensional echocardiography is not perfect, and we used echoes from 80% of normal subjects in this study, but only some 60% of the patients with coronary artery disease who are examined in our laboratory.

Data analysis

We examined the echocardiographic recordings in real-time, slow motion and stop-frame mode. We traced the outline of the left ventricular silhouette at end-di- astole and end-systole, timing end-diastole to the onset of the QRS complex of the electrocardiogram and using the smallest ventricular size for end-systole. The data

were digitized using a curve tracer (Grafpen, Science Accessories Corporation, U.S.A.) for computer processing. The computer program divided the circumference

of the left ventricle into 500 equally spaced separate data points for analysis and excluded the mitral valve from the analysis.

Computer analysis was performed using a PDP 15/40 computer. There is no ideal

method for quantitating regional ejection fraction [l-5] which corrects for total cardiac motion while faithfully displaying regional contraction patterns. We elected to use in this study a method which analyses segmental contraction about the long axis of the ventricle since we believe that it provides an acceptable representation of the left ventricular contraction pattern [lo].

The method divides the ventricle into 12 regions, bisecting the ventricle along its long axis and dividing each half into 6 regions (Fig. 1). Three-dimensional half-circle

Anterolateral I

Apex D

Fig. 1. Left ventricular outline at end-diastole (D) and end-systole (S) traced from the real-time

two-dimensional echocardiogram (apical view). The ventricle was divided into 12 segments. The volume of

each segment was calculated in D and S by integrating the volume of a series of hemicylinders constructed within that region. Regional ejection fraction was calculated for each segment as the percentage volume change from D to S.

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segments or cylinders are generated in each region for every subsegment within the

area. The method is similar to that used by Cribier et al. [ 1 I] (graphic integration

method). The process was performed separately at both end-diastole and end-systole

to identify and define 12 regions of the ventricle at each point in time. Comparison

between each corresponding pair of end-diastolic and end-systolic regions provided

the regional ejection fraction for that segment. The sum of the volumes of the

individual regions of the ventricle at end-diastole and end-systole provided total

(global) left ventricular volume and ejection fraction.

Results

The pattern of regional ventricular ejection fraction in normal subjects is given in Fig. 2. The graph was very similar to the normal graph of regional ejection fraction for our laboratory derived from angiographic data in a larger group of 20 subjects

[IO]. although the 4 chamber view echo systematically underestimated regional

ejection fraction in regions 7- 11, the anterolateral surface of the left ventricle. This may be due to difficulty in the quality of endocardial visualization in this region of

the ventricle on the echo. As on the angiogram, there was aImost homogeneous contraction of the 12

different regions (regional ejection fraction 54-74%) and the standard deviation was

fairly small except in segment 1 (inferoseptal adjacent to mitral valve) and 6 (apex).

There was a tendency to a lower ejection fraction in the apical region.

In each patient with coronary artery disease the echo identified a region(s) of abnormal contraction, and in general this was in keeping with the angiographic

findings (Table I). The correlation between the extent and severity of echocardio-

graphic and angiographic wall motion abnormality was close in the apical region but

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Fig. 2. Echocardiographic regional ejection fraction (EF) (0) in normal subjects (mean* ISD). The

broken line and shaded area represent the normal angiographic regional EF for our laboratory.

Echocardiographic contraction is slightly less in the anterolateral region of the ventricle (regions 7- 1 I)

compared with the angiogram.

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Fig. 3a. Regional ejection fraction (EF) in normal subjects (A) (mean-t ISD) and in a patient with

coronary artery disease (*). In the coronary patient, there was a striking abnormality of the regional

contraction pattern with apical dyskinesis and a zone of good contraction on either side.

less exact near the base of the ventricle. We have no information about the accuracy of the method in patients who have small areas of regional ventricular dysfunction, since all the patients had suffered previous myocardial infraction.

The results of the detailed echocardiographic analysis of regional ejection fraction are given for selected patients in Fig. 3. The graphs were different in each patient,

depending on the site and severity of his contraction abnormality. A decreased regional ejection fraction implies hypokinesis of that region of the ventricle, an

ejection fraction near zero indicates akinesis. and a negative regional ejection

fraction dyskinesis of the segment.

Fig. 3b. Regional ejection fraction (EF) in normal subjects (A) (mean? 1s.D) and in a patient with severe

coronary artery disease (*). There were regional differences of contraction in the coronary patient with

hypokinesis of the base and akinesis and dyskinesis near the apex.

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-10. Global EF= 30%

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Fig. 4. Regional ejection fraction (EF) graph in a patient with congestive cardiomyopathy. There was a

uniform decrease in EF (hypokinesis) compared with the normal subjects (A).

Fig. 3a shows a patient with a global left ventricular ejection fraction of 31%.

Dyskinesis was localized to the apical region of the ventricle and there was an area

of good contraction on both sides of the dyskinetic zone. These findings were

confirmed at angiography, and the patient subsequently underwent aneurysmec-

tomy. Fig. 3b shows a patient with more severe ventricular dysfunction involving all

regions of the ventricle. There is dyskinesis of the distal anterolateral surface

(regions 7, 8, 9) and hypo- or akinesis of the remainder of the ventricle. Regional

ejection fraction ranged from -17 to 35% while global ejection fraction was 15%. Left ventricular cineangiocardiography showed severe, extensive left ventricular

dysfunction and the patient was unsuitable for aneursmectomy. Fig. 4 shows the graphic display in a patient with severe congestive cardiomyopa-

thy. The curve is essentially parallel to that of the normal subjects, but there was a downward shift indicating a uniform decrease in ventricular contraction and re-

gional ejection fraction (range 11 to 39%). Global ejection fraction was reduced to 30%. The findings in the other patient with congestive cardiomyopathy were similar.

Discussion

Regional ventricular dysfunction

Assessment of global ventricular contraction provides data relating to overall

cardiac function, but the measurements depend on preload and afterload in addition to the state of underlying myocardial contractility. Moreover, coronary artery

disease does not cause uniform myocardial damage, and accurate assessment of the coronary patient requires a detailed study of each individual myocardial segment. The study of regional myocardial contraction patterns compares different areas of

68

the ventricular wall and quantitates the severity of the localized contraction

abnormalities (regional ejection fraction) in patients with coronary artery disease.

These data are essential in the pre-operative assessment of coronary patients.

The identification and quantitation of regional abnormalities of left ventricular

contraction previously depended on invasive cardiac catheterization and left ventric-

ular angiography [l-5]. The introduction of radionuclide ventriculography provided

a non-invasive alternative [6-91, but although the method measures segment volume,

it is costly, its accuracy in the precise delineation of the left ventricular silhouette is not optimal, and it is at present not possible to make beat-to-beat measurements.

Regional ventricular dysfunction from the two-dimensional echocardiogram

Heger et al. used a ventricular ‘score’ system to study patients with myocardial infarction. The score was based on the number of areas of the ventricle involved in

regional asynergy and their severity, but the method is only semi-quantitative 1171. Eaton et al. used only the short axis echo view in their studies [18]. Moynihan et al.

[19] and Parisi et al. [20] constructed graphical plots of regional left ventricular function similar to ours from short axis slices through the ventricle with analysis of

the apex from the apical 4-chamber view. The present study showed again that it is possible to make a detailed analysis of

regional ventricular performance from the two-dimensional echocardiogram in a

manner similar to that from cineangiography. While optimal real-time echocardio-

graphic images cannot be achieved in all patients, the quality of echocardiography is

improving dramatically so that better images will be obtained in a larger number of patients in the near future, while definition of the endocardium is now more

accurate. A high quality echocardiogram defines the true left ventricular wall rather than its

cavity as is the case using angiography or radio-nuclear scanning techniques. Since

the transducer is ‘fixed’ to the chest wall in the region of the apex by the operator throughout the cardiac cycle, the problem of fixed external reference points for analysis of ventricular wall motion is lessened [ 19-241, although rotational chances

probably occur about the long axis of the ventricle. A reproducible consistent pattern of ventricular contraction found in normal

subjects was uniform contraction of all segments of the ventricle with a slightly

lower regional ejection fraction in the apical region. In coronary artery disease, there were typically segmental abnormalities of ventricular contraction, and the picture

differed from patient to patient with regard to the localization of the abnormality. its

extent and severity and the behaviour of the ‘uninvolved’ myocardium. The correla-

tion of echocardiographic and angiographic findings was close in the apical region of the ventricle, but discrepancies were seen in the region of the base in some patients. These differences can be explained by the fact that both the echo and angio planes always passed through the apex of the ventricle irrespective of the exact plane of the echo beam. The echocardiographic and angiocardiographic planes were not identi- cal, however, in the region of the base.

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Quantitation of regional ventricular function may be useful in making decisions about the management and prognosis of patients with coronary disease and may provide a quantitative guide in the selection of patients for cardiac catheterization, coronary bypass surgery and ventricular aneurysmectomy. In contrast, the contrac- tion pattern in congestive cardiomyopathy was one of a generalized and uniform decrease in contraction of all segments, although global ejection fraction was similar to that seen in coronary disease. The graphic output of the results provided a simple, visual display of regional ventricular function in normal subjects and in patients with cardiac disease.

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