- Email: [email protected]
Accuracy of nondirected and directed M-mode echocardiography as an estimate of left atrial size
1208
BRIEF REPORTS
terization confirmed the presence of an LA mass,normal left ventricular function, mild mitral regurgitation and no coronary artery disease.At surgery, the myxoma was removed without difficulty (Fig. 31. The patient had an uneventful postoperative course and continues to do well 8 months later. The present case illustrates how an unusual exercise thallium image led to the suspicion of an atria1 abnormality and the eventual diagnosis of atria1myxoma by echocardiography. The findings of increased lung activity in the presence of normal left ventricular thallium distribution and right ventricular hypertrophied dilatation raise a number of diagnostic possibilities; these include balanced reduction of coronary blood flow as found in patients with Z-vesseldisease, any etiology of increased left ventricular end-diastolic pressure, mitral regurgitation or atria1 abnormalities such as mitral stenosis,myxoma or septal defects. Triple-vessel disease or left ventricular hypertrophies would not explain the dilated and hypertrophied right
Accuracy of Nondirected and Directed M-Mode Echocardiographyas an Estimate of left Atrial Size MARK R. WADE, MD P. ANTHONY N. CHANDRARATNA, MD CHERYL L. REID, MD SHOA-LIN LIN, MD SHAHBUDIN H. RAHIMTOOLA, MB, FRCP
M
-mode echocardiography has customarily been used to assessleft atria1 [LA) size noninvasively; it is thought that this provided a more accurate estimate than chest x-ray. Normal subjects have been studied systematically and normal ranges of M-mode measurements defined with good reproducibility.1-3 However, a good correlation between M-mode LA dimension and LA volume has not been consistently demonstrated. Schabelman et al4 compared M-mode LA dimension with biplane angiographic volume and found a poor correlation (r = 0.50,y = 1.5x - 10.9).The best correlation of these 2 parameters they could attain was by fitting the M-mode dimension to a power function (y = 3.7~9 and then the correlation coefficient was only 0.69.Two-dimensional (D) echocardiography has also been used to assistin the measurement of LA dimension,5 and there has been some evidence suggesting that the use of 2-D echocardiographic direction of the M-mode beam can improve the accuracy From the Section of Cardiology, Department of Medicine, Los Angeles County-University of Southern California Medical Center, University of Southern California School of Medicine, Los Angeles, California 90033. Manuscript received April 27, 1987; revised manuscript received and accepted July 10,1987.
ventricle, nor would one expect to find a normal left ventricular size with mitral regurgitation. Thus, the triad of atria1septal defect, mitral stenosisor LA myxoma seem most likely and are easily differentiated by 2dimensional echocardiography. In contrast to many other cardiac abnormalities, atria1myxomas are usually cured when the tumor is removed.4v5 The possibility of an atria1 tumor should not be overlooked when evidence suggestinga myxoma is seen on testsperformed for other reasons. 1. Conces DJ, Vix VA, Klatle EC. GatedMR imaging of left atrial myxomas. Radiology 1985;156:445-447. 2. Ezekowitz MD, Smith EO, Rankin R, Harrison LH, Krous HF. Left atrial mass: diagnostic value of transesophageal Z-dimensional echocardiography and indium-111 platelet scintigraphy. Am f Cardiol 1983;51:1563-1564. 3. Tamari I, Goldberg HL, Moses JW, Fisher J, Borer JS. Left atrial myxoma: diagnosis by digital subtractionintravenousangiography.Cathet Cardiovasc Diagn 1982;12:26-29. 4. SuttonMG, Mercier LA, Giuliani ER,Lie JT.Atria1myxomas a review of clinical experience in 40 patients. Mayo Clin Proc 1980;55:371-376. 5. Fyke FE, Seward JB, Edward WD, Miller FA, Reeder GS, Schattenberg TT, Shub C, Callahan JAzTajik AJ. Primary cardiac tumors: experience with 30 consecutive patients since the introduction of two-dimensional echocardiography. fACC
1985;5:1465-1473.
of unidirectional echocardiographic measurement in predicting LA size.6 We report an evaluation of the relation of M-mode echocardiographic LA dimension, both independently and with 2-D echocardiographic direction, to LA volume. Twenty-nine patients, without selection by diagnosis, undergoing diagnostic clinical echocardiographic studies formed the study population. All patients had both parasternal M-mode and complete 2-D studies using IREX echocardiographic equipment. M-mode measurement of the LA antero-posterior dimension at end-systole was initially performed in “blind” fashion, without 2-D guidance, in accordance with the recommendations of the American Society of Echocardiography.7 Subsequently, whenever technically possible, M-mode measurement of the same dimension was repeated using 2-D echocardiographic direction in both the parasternal long-axis and short-axis projections, for optimal placement of the M-mode cursor within the chamber. Placement of the beam was considered to be optimal when the cursor was directed through the aortic valve to the most central LA position attainable. LA end-systolic biplane volume was calculated from 2-D echocardiographic images, using the apical 4- and Z-chamber views by the Simpson’s rule method whenever both views were of adequate technical quality. All recorded volumes were the mean of at least 3 pairs of orthogonal images. Each M-mode measurement and volume calculation was performed twice by 1 observer, on separate occasions.At the time of the second set of readings, the observer was blinded to the results of his first readings. For each parameter, analyses of intraobserver variability were performed using linear regression analysis.All readings were also performed by a second observer, blinded to the results obtained by the first observer, and compared with the initial set of readings
November
TABLE 1 Left Atrial M-Mode Dimensions Non-d
15, 1967
and Calculated
THE AMERICAN
JOURNAL
OF CARDIOLOGY
SAX-d
LAXd M-Mode (mm) (n = 24)
M-Mode (mm) (n = 27)
Volume (ml) (rl = 21)
1 2 3 4 5 6 7
38 38 38 43 36 42 36
36 46 42 36
40 47 38 50 35
36 79 42 106 35 50 -
8 9
45 38
42 -
44 40
-
10 II 12 13 14
34 28 60 32 45
35 34 62 31 50
35 35 62 33 45
51 26 189 -
15 16 17
38 45 61
46 63
44 44 58
-
18 19 20 21 22 23
37 36 30 57 35 62
45 45 37 58 38 62
44 43 38 59 40 62
69 25 36 107 64 -
24 25 26
36 52 47
35 53 48
34 50 55
31 70 -
33 40 38 41 f 9
35 40 38 44 f IO’
38 41 37 44 f 97
24 171 38 63 f 46
27 28 29 Mean f
SD
~ZOC
Vo~um@a
M-Mode (mm) (rl = 29)
Pt
Volume 50
33
46
“p = 0.007 for Non-d M-Mode vs LAX-d M-Mode. tp = 0.004 for Non-d M-Mode vs SAX-d M-Mode. p = 0.76 for LAX-d M-Mode vs SAX-d M-Mode. LAX-d M-Mode = parasternal long-axis 2-D echocardiogram-directed M-Mode; Non-d M-Mode = parasternal nondirected M-Mode echo: SAX-d M-Mode = parasternal short-axis 2-D echocardiogram-directed M-Mode; SD = standard deviation.
TABLE II
Left Atrial M-Mode Dimension
Method lntraobserver Variability Nondirected Long-axis directed Short-axis directed lnterobserver Variability Nondirected Long-axis directed Short-axis directed
Variability
n
Regression
Equation
SEE
R
P
29 24 27
y = y =
3.63 + 0.93x 0.46 + 0.99x 1.63 + 0.96x
2.15 1.67 2.17
0.97 0.99 0.97
29 24 27
y = 0.21 + 1.00x y = -0.03 + 1.00x y = -2.35 + 1.03x
2.42 4.01 3.01
0.97 0.93 0.95
Y=
SEE = standard error.
of the latter. Analyses of interobserver variability were performed using linear regression analysis. For all remaining analyses, the initial readings of the first observer were used. Linear regression analyses of the measurements made by each M-mode technique (nondirected, long-axis 2-D echocardiogram-directed and short-axis 2-D echocardiogram-directed) versus volume were performed and correlation coefficients were determined. The measurements made by each of the 3 M-mode methods (nondirected, long-axis 2-D-directed and short-axis 2-D-directed) were compared separately
with each other by paired nonparametric analysis, using the a-tailed Wilcoxon signed ranks test. This was done to determine if there were any significant overall differences between the measurements obtained by the different M-mode techniques. All 29 patients had satisfactory nondirected Mmode echocardiography of the left atrium. It was technically possible to perform parasternal long-axis and short-axis 2-D echocardiogram-directed M-mode LA measurements in only 24 and 27 patients, respectively. Twenty-one patients had 2-D echocardiography of adequate quality in both the apical 4- and &chamber
1210
BRIEF REPORTS
80
../
1
.
60
.
n=21 y=21.81+0.61~
l a
/
SEE=10.88
0.
wO.93
:
.
p
0 Left
50 atrial volume
100 (ml) : first
1
150 measurement
FIGURE 1. Variability of left atrial volume. A, intraobserver variability; correlation between 2 separate measurements made by first observer. B, interobserver variability; correlation between initial measurements by first observer and measurements by second observer.
200
200 i 160
80
0
’ 0 Left
6
I 50 atria1 volume
I
100 (ml) : first measurement
150 by first
I 200 observer
.
. y.32.33+0.12x SEES.22 r-0.66 p=o.oo,
.’
0
’ 0
lk18 y.3!3.63+3.11x SEE=6.44 eo.64 pPo.004
I 50
100
150
200
Left atrial volume (ml) FIGURE 2. Relation of nondirected M-mode left atrial echocardiographic dimension to left atrial volume.
views for calculation of LA volume. Table I shows the results of the initial set of determinations of the Mmode dimensions and the calculated volumes. Repeated determinations of M-mode measurements by the initial observer and a second observer for analysis of intra- and interobserver variability revealed excellent correlation (Table 11).Analyses of intra- and interobserver variability of the LA volume determinations yielded similarly strong correlation [Fig. 1). The relations of each M-mode LA measurement to LA volume are shown in Figures 2,3 and 4. Measurements by all 3 M-mode techniques correlated poorly with LA volume. A specific example is patient no. 28 (Table I) who was found to have high-normal LA M-mode dimensions by all 3 techniques (40 to 41 mm) but also a mark-
0
I
I
50
100 Left
atrial
volume
I 150
4 200
(ml)
FIGURE 3. Relation of long-axis, 2-D echocardiogram-directed, mode left atrial dimension to left atrial volume.
M-
edly high LA volume (172 ml). Although none of the M-mode methods was found to be a good predictor of LA volume, both 2-D echocardiogram-directed Mmode techniques were found to yield significantly larger LA dimensions than nondirected M-mdde (p = 0.007 and 0.004 for long-axis and short-axis 2-D echocardiogram-directed M-mode, respectively). There was no significant difference between the two 2-D echocardiogram-directed techniques [Table I]. Early studies reported that LA M-mode dimension correlated well with LA angiographic area.8rgThus, it was held that M-mode echocardiographic LA measurement was an adequate means of assessingLA size. These observations led to M-mode LA dimension de-
November
15,1987
termination being used for clinical purposes. For example, atria1 fibrillation has been reported to be more common in patients whose M-mode LA measurement is large-l0 In addition, long-term maintenance in sinus rhythm after cardioversion from atria1 fibrillation has been reported to be less likely when the LA M-mode dimension is large. lo Therefore, M-mode LA evaluation has often been used to make clinical decisions regarding anticoagulation and cardioversion in patients with atria1 fibrillation. Hence, it is important to know whether M-mode echocardiography can accurately predict LA size. Calculation of LA biplane volume from 2-D echocardiographic images using the apical 4- and 2-chamber views has been described and correlates well with angiographic volume as demonstrated by Schabelman et al4 (r = 0.86) and Hiraishi et al6 (r = 0.92). The present study demonstrates poor correlation (r = 0.66) between nondirected M-mode LA dimension and echocardiographic LA volume. Correlation between 2-D echocardiogram-directed, M-mode LA dimension and LA volume was equally poor (r 7 0.64 and r = 0.65 for the long-axis and short-axis, 2-D echocardiogramdirected projections, respectively]. In our study, intraand interobserver variability was very little. Thus, the poor correlation of M-mode dimension with volume does not appear to be the result of lack of precision of the techniques used. Our data suggest that M-mode measurement of the left atrium, even with 2-D echocardiographic direction, does not accurately predict LA size. Although in specific patients known LA distortion might be corrected for, caution should be exercised when making clinical decisions based on M-mode and 2-D echocardiographic measurements of LA dimension. To determine LA size, LA volumes should be calculated.
Diastolic Abnormalities of Postischemic “Stunned” Myocardium KARIN PRZYKLENK, PhD BHARAT PATEL, MD ROBERT A. KLONER, MD, PhD
M
yocardial “stunning” or postischemic contractile dysfunction in the absence of myocyte necrosis1 has by convention been quantified using indexes of systolic function (i.e., segment shortening or wall thickening),zv3yet alterations in the diastolic components of the cardiac cycle associated with stunning remain largely undefined. Recent evidence suggests that abnormalities in diastolic function persist beyond the reFrom the Department of Internal Medicine, Division of Cardiology, Harper Hospital, and Wayne State University, Detroit, Michigan. Manuscript received May 11, 1987; revised manuscript received and accepted July Z&,1987.
THE AMERICAN
JOURNAL
OF CARDIOLOGY
Volume 60
WI9
Y-36.33+0.1 SEE-6.03
ezol z
I 0
/
50
100
Left
atrial
volume
ir
I
,
150
200
(ml)
FIGURE 4. Relation of short-axis, 2-Q echocardiogram-dkected mode left atrial dimension to left atrial volume.
kb
1. Henry WL, Gardin JM, Ware JH. Echocardiographic measurements in normal subjects from infancy to old age. Circulation 1980;62:1054-1061, 2: Triulzi M, Gillam LD, Gentile F, Newell JB, Weyman AE. Normal oduft cross-sectional echqcardiographic values: Iinear dimensions and chamber areas. Echocardiography 1984;1:403-426. 3. Gardin JM, Henry WL, Savage DD, Ware JH, Burn C, Borer JS.Echocardiographic measurements in normal subjects: evaluation of an adult population without clinically apparent heart disease. J C!in Ultrasound i979;7:439-447. 4. Schabelman S, Schiller NB, Silverman NH, Ports TH. Left atria1 volume estimation by two-dimensional echqcardiography. Cathet Cardrovasc Diagn l981;7:165-178. 5. Schnittger I, Gordon EP, Fitzgerald PJ,Popp RL. Standardized intracardiac measurementsof two-dimensionalechocardiography.JACC 1983;2:934-938. 6. Hiraishi S, DiSessa TG, Jarmakani JM, Nakanishi T, Isabel-Jones J, Friedman WF. Two-dimensional echocardiographic assessmentoffeft atrial size in children. Am f Cordial 1983;52:1249-1257, 7. Sahn DJ. DeMaria A, Kisslo ], Weyman A. The committee on M-mode standardization of the American Society of Echocardiography: recommendations regarding quantitation in M-mode echocordiography: results of a survey of echocardiographic measurements. Circulation 1978;58:1072-1083, 8. Hirata T, Wolfe SB, Popp RL, Helm& CH. Feigenbaum H. Estimation of left atria1 size using ultrasound. Am Heart J 1969;78:43-52. 9. ten Cate FJ, Kloster FE, Van Dorp WG, Meester GT, Roelandt J. Dimensions and volumes of left atrium and ventrjcle determined by single beam echocardiography. Br Heart J 1974;36:737-746. 10. Henry WL, Morganroth J, Pearlman AS, Clark GE, Redwood DR, Itscoitz $3, Epstein SE. Relation between echocardiographically determined left atrial size and atria1 fibrillation. Circulation 1976;53:273-279.
covery of normal systolic function in patients rendered ischemic for brief (15 to 75 second] periods during percutaneous transluminal coronary angioplasty; thus, the diastolic properties of the stunned, reperfused myocardium may be of considerable clinical importance.4,5This report quantifies and compares indexes of both systolic contraction and isovolumic relaxation in a canine model of the postischemic, stunned myocardium. Retrospective analysis was performed on data obtained from 9 anesthetized, open-chest mongrel dogs that underwent 15 minutes of proximal left anterior descending (LAD) coronary artery occlusion followed by 3 hours of reperfusion as part of a previous protocol.” Before occlusion, a high fidelity micro-tipped pressure transducer was positioned within the left ventricular (Lv) cavity for measurement of LV pressure and LV dP/dt, and 1 pair of ultrasonic crystals was inserted within the center of the soon to be ischemic LAD bed and oriented purallel to the atrioventricular groove. All 9 dogs received saline alone (no pharmacologic intervention) during coronary occlusion and the initial XI minutes of reflow; that is, n = 9 at 30
BRIEF REPORTS
terization confirmed the presence of an LA mass,normal left ventricular function, mild mitral regurgitation and no coronary artery disease.At surgery, the myxoma was removed without difficulty (Fig. 31. The patient had an uneventful postoperative course and continues to do well 8 months later. The present case illustrates how an unusual exercise thallium image led to the suspicion of an atria1 abnormality and the eventual diagnosis of atria1myxoma by echocardiography. The findings of increased lung activity in the presence of normal left ventricular thallium distribution and right ventricular hypertrophied dilatation raise a number of diagnostic possibilities; these include balanced reduction of coronary blood flow as found in patients with Z-vesseldisease, any etiology of increased left ventricular end-diastolic pressure, mitral regurgitation or atria1 abnormalities such as mitral stenosis,myxoma or septal defects. Triple-vessel disease or left ventricular hypertrophies would not explain the dilated and hypertrophied right
Accuracy of Nondirected and Directed M-Mode Echocardiographyas an Estimate of left Atrial Size MARK R. WADE, MD P. ANTHONY N. CHANDRARATNA, MD CHERYL L. REID, MD SHOA-LIN LIN, MD SHAHBUDIN H. RAHIMTOOLA, MB, FRCP
M
-mode echocardiography has customarily been used to assessleft atria1 [LA) size noninvasively; it is thought that this provided a more accurate estimate than chest x-ray. Normal subjects have been studied systematically and normal ranges of M-mode measurements defined with good reproducibility.1-3 However, a good correlation between M-mode LA dimension and LA volume has not been consistently demonstrated. Schabelman et al4 compared M-mode LA dimension with biplane angiographic volume and found a poor correlation (r = 0.50,y = 1.5x - 10.9).The best correlation of these 2 parameters they could attain was by fitting the M-mode dimension to a power function (y = 3.7~9 and then the correlation coefficient was only 0.69.Two-dimensional (D) echocardiography has also been used to assistin the measurement of LA dimension,5 and there has been some evidence suggesting that the use of 2-D echocardiographic direction of the M-mode beam can improve the accuracy From the Section of Cardiology, Department of Medicine, Los Angeles County-University of Southern California Medical Center, University of Southern California School of Medicine, Los Angeles, California 90033. Manuscript received April 27, 1987; revised manuscript received and accepted July 10,1987.
ventricle, nor would one expect to find a normal left ventricular size with mitral regurgitation. Thus, the triad of atria1septal defect, mitral stenosisor LA myxoma seem most likely and are easily differentiated by 2dimensional echocardiography. In contrast to many other cardiac abnormalities, atria1myxomas are usually cured when the tumor is removed.4v5 The possibility of an atria1 tumor should not be overlooked when evidence suggestinga myxoma is seen on testsperformed for other reasons. 1. Conces DJ, Vix VA, Klatle EC. GatedMR imaging of left atrial myxomas. Radiology 1985;156:445-447. 2. Ezekowitz MD, Smith EO, Rankin R, Harrison LH, Krous HF. Left atrial mass: diagnostic value of transesophageal Z-dimensional echocardiography and indium-111 platelet scintigraphy. Am f Cardiol 1983;51:1563-1564. 3. Tamari I, Goldberg HL, Moses JW, Fisher J, Borer JS. Left atrial myxoma: diagnosis by digital subtractionintravenousangiography.Cathet Cardiovasc Diagn 1982;12:26-29. 4. SuttonMG, Mercier LA, Giuliani ER,Lie JT.Atria1myxomas a review of clinical experience in 40 patients. Mayo Clin Proc 1980;55:371-376. 5. Fyke FE, Seward JB, Edward WD, Miller FA, Reeder GS, Schattenberg TT, Shub C, Callahan JAzTajik AJ. Primary cardiac tumors: experience with 30 consecutive patients since the introduction of two-dimensional echocardiography. fACC
1985;5:1465-1473.
of unidirectional echocardiographic measurement in predicting LA size.6 We report an evaluation of the relation of M-mode echocardiographic LA dimension, both independently and with 2-D echocardiographic direction, to LA volume. Twenty-nine patients, without selection by diagnosis, undergoing diagnostic clinical echocardiographic studies formed the study population. All patients had both parasternal M-mode and complete 2-D studies using IREX echocardiographic equipment. M-mode measurement of the LA antero-posterior dimension at end-systole was initially performed in “blind” fashion, without 2-D guidance, in accordance with the recommendations of the American Society of Echocardiography.7 Subsequently, whenever technically possible, M-mode measurement of the same dimension was repeated using 2-D echocardiographic direction in both the parasternal long-axis and short-axis projections, for optimal placement of the M-mode cursor within the chamber. Placement of the beam was considered to be optimal when the cursor was directed through the aortic valve to the most central LA position attainable. LA end-systolic biplane volume was calculated from 2-D echocardiographic images, using the apical 4- and Z-chamber views by the Simpson’s rule method whenever both views were of adequate technical quality. All recorded volumes were the mean of at least 3 pairs of orthogonal images. Each M-mode measurement and volume calculation was performed twice by 1 observer, on separate occasions.At the time of the second set of readings, the observer was blinded to the results of his first readings. For each parameter, analyses of intraobserver variability were performed using linear regression analysis.All readings were also performed by a second observer, blinded to the results obtained by the first observer, and compared with the initial set of readings
November
TABLE 1 Left Atrial M-Mode Dimensions Non-d
15, 1967
and Calculated
THE AMERICAN
JOURNAL
OF CARDIOLOGY
SAX-d
LAXd M-Mode (mm) (n = 24)
M-Mode (mm) (n = 27)
Volume (ml) (rl = 21)
1 2 3 4 5 6 7
38 38 38 43 36 42 36
36 46 42 36
40 47 38 50 35
36 79 42 106 35 50 -
8 9
45 38
42 -
44 40
-
10 II 12 13 14
34 28 60 32 45
35 34 62 31 50
35 35 62 33 45
51 26 189 -
15 16 17
38 45 61
46 63
44 44 58
-
18 19 20 21 22 23
37 36 30 57 35 62
45 45 37 58 38 62
44 43 38 59 40 62
69 25 36 107 64 -
24 25 26
36 52 47
35 53 48
34 50 55
31 70 -
33 40 38 41 f 9
35 40 38 44 f IO’
38 41 37 44 f 97
24 171 38 63 f 46
27 28 29 Mean f
SD
~ZOC
Vo~um@a
M-Mode (mm) (rl = 29)
Pt
Volume 50
33
46
“p = 0.007 for Non-d M-Mode vs LAX-d M-Mode. tp = 0.004 for Non-d M-Mode vs SAX-d M-Mode. p = 0.76 for LAX-d M-Mode vs SAX-d M-Mode. LAX-d M-Mode = parasternal long-axis 2-D echocardiogram-directed M-Mode; Non-d M-Mode = parasternal nondirected M-Mode echo: SAX-d M-Mode = parasternal short-axis 2-D echocardiogram-directed M-Mode; SD = standard deviation.
TABLE II
Left Atrial M-Mode Dimension
Method lntraobserver Variability Nondirected Long-axis directed Short-axis directed lnterobserver Variability Nondirected Long-axis directed Short-axis directed
Variability
n
Regression
Equation
SEE
R
P
29 24 27
y = y =
3.63 + 0.93x 0.46 + 0.99x 1.63 + 0.96x
2.15 1.67 2.17
0.97 0.99 0.97
29 24 27
y = 0.21 + 1.00x y = -0.03 + 1.00x y = -2.35 + 1.03x
2.42 4.01 3.01
0.97 0.93 0.95
Y=
SEE = standard error.
of the latter. Analyses of interobserver variability were performed using linear regression analysis. For all remaining analyses, the initial readings of the first observer were used. Linear regression analyses of the measurements made by each M-mode technique (nondirected, long-axis 2-D echocardiogram-directed and short-axis 2-D echocardiogram-directed) versus volume were performed and correlation coefficients were determined. The measurements made by each of the 3 M-mode methods (nondirected, long-axis 2-D-directed and short-axis 2-D-directed) were compared separately
with each other by paired nonparametric analysis, using the a-tailed Wilcoxon signed ranks test. This was done to determine if there were any significant overall differences between the measurements obtained by the different M-mode techniques. All 29 patients had satisfactory nondirected Mmode echocardiography of the left atrium. It was technically possible to perform parasternal long-axis and short-axis 2-D echocardiogram-directed M-mode LA measurements in only 24 and 27 patients, respectively. Twenty-one patients had 2-D echocardiography of adequate quality in both the apical 4- and &chamber
1210
BRIEF REPORTS
80
../
1
.
60
.
n=21 y=21.81+0.61~
l a
/
SEE=10.88
0.
wO.93
:
.
p
0 Left
50 atrial volume
100 (ml) : first
1
150 measurement
FIGURE 1. Variability of left atrial volume. A, intraobserver variability; correlation between 2 separate measurements made by first observer. B, interobserver variability; correlation between initial measurements by first observer and measurements by second observer.
200
200 i 160
80
0
’ 0 Left
6
I 50 atria1 volume
I
100 (ml) : first measurement
150 by first
I 200 observer
.
. y.32.33+0.12x SEES.22 r-0.66 p=o.oo,
.’
0
’ 0
lk18 y.3!3.63+3.11x SEE=6.44 eo.64 pPo.004
I 50
100
150
200
Left atrial volume (ml) FIGURE 2. Relation of nondirected M-mode left atrial echocardiographic dimension to left atrial volume.
views for calculation of LA volume. Table I shows the results of the initial set of determinations of the Mmode dimensions and the calculated volumes. Repeated determinations of M-mode measurements by the initial observer and a second observer for analysis of intra- and interobserver variability revealed excellent correlation (Table 11).Analyses of intra- and interobserver variability of the LA volume determinations yielded similarly strong correlation [Fig. 1). The relations of each M-mode LA measurement to LA volume are shown in Figures 2,3 and 4. Measurements by all 3 M-mode techniques correlated poorly with LA volume. A specific example is patient no. 28 (Table I) who was found to have high-normal LA M-mode dimensions by all 3 techniques (40 to 41 mm) but also a mark-
0
I
I
50
100 Left
atrial
volume
I 150
4 200
(ml)
FIGURE 3. Relation of long-axis, 2-D echocardiogram-directed, mode left atrial dimension to left atrial volume.
M-
edly high LA volume (172 ml). Although none of the M-mode methods was found to be a good predictor of LA volume, both 2-D echocardiogram-directed Mmode techniques were found to yield significantly larger LA dimensions than nondirected M-mdde (p = 0.007 and 0.004 for long-axis and short-axis 2-D echocardiogram-directed M-mode, respectively). There was no significant difference between the two 2-D echocardiogram-directed techniques [Table I]. Early studies reported that LA M-mode dimension correlated well with LA angiographic area.8rgThus, it was held that M-mode echocardiographic LA measurement was an adequate means of assessingLA size. These observations led to M-mode LA dimension de-
November
15,1987
termination being used for clinical purposes. For example, atria1 fibrillation has been reported to be more common in patients whose M-mode LA measurement is large-l0 In addition, long-term maintenance in sinus rhythm after cardioversion from atria1 fibrillation has been reported to be less likely when the LA M-mode dimension is large. lo Therefore, M-mode LA evaluation has often been used to make clinical decisions regarding anticoagulation and cardioversion in patients with atria1 fibrillation. Hence, it is important to know whether M-mode echocardiography can accurately predict LA size. Calculation of LA biplane volume from 2-D echocardiographic images using the apical 4- and 2-chamber views has been described and correlates well with angiographic volume as demonstrated by Schabelman et al4 (r = 0.86) and Hiraishi et al6 (r = 0.92). The present study demonstrates poor correlation (r = 0.66) between nondirected M-mode LA dimension and echocardiographic LA volume. Correlation between 2-D echocardiogram-directed, M-mode LA dimension and LA volume was equally poor (r 7 0.64 and r = 0.65 for the long-axis and short-axis, 2-D echocardiogramdirected projections, respectively]. In our study, intraand interobserver variability was very little. Thus, the poor correlation of M-mode dimension with volume does not appear to be the result of lack of precision of the techniques used. Our data suggest that M-mode measurement of the left atrium, even with 2-D echocardiographic direction, does not accurately predict LA size. Although in specific patients known LA distortion might be corrected for, caution should be exercised when making clinical decisions based on M-mode and 2-D echocardiographic measurements of LA dimension. To determine LA size, LA volumes should be calculated.
Diastolic Abnormalities of Postischemic “Stunned” Myocardium KARIN PRZYKLENK, PhD BHARAT PATEL, MD ROBERT A. KLONER, MD, PhD
M
yocardial “stunning” or postischemic contractile dysfunction in the absence of myocyte necrosis1 has by convention been quantified using indexes of systolic function (i.e., segment shortening or wall thickening),zv3yet alterations in the diastolic components of the cardiac cycle associated with stunning remain largely undefined. Recent evidence suggests that abnormalities in diastolic function persist beyond the reFrom the Department of Internal Medicine, Division of Cardiology, Harper Hospital, and Wayne State University, Detroit, Michigan. Manuscript received May 11, 1987; revised manuscript received and accepted July Z&,1987.
THE AMERICAN
JOURNAL
OF CARDIOLOGY
Volume 60
WI9
Y-36.33+0.1 SEE-6.03
ezol z
I 0
/
50
100
Left
atrial
volume
ir
I
,
150
200
(ml)
FIGURE 4. Relation of short-axis, 2-Q echocardiogram-dkected mode left atrial dimension to left atrial volume.
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covery of normal systolic function in patients rendered ischemic for brief (15 to 75 second] periods during percutaneous transluminal coronary angioplasty; thus, the diastolic properties of the stunned, reperfused myocardium may be of considerable clinical importance.4,5This report quantifies and compares indexes of both systolic contraction and isovolumic relaxation in a canine model of the postischemic, stunned myocardium. Retrospective analysis was performed on data obtained from 9 anesthetized, open-chest mongrel dogs that underwent 15 minutes of proximal left anterior descending (LAD) coronary artery occlusion followed by 3 hours of reperfusion as part of a previous protocol.” Before occlusion, a high fidelity micro-tipped pressure transducer was positioned within the left ventricular (Lv) cavity for measurement of LV pressure and LV dP/dt, and 1 pair of ultrasonic crystals was inserted within the center of the soon to be ischemic LAD bed and oriented purallel to the atrioventricular groove. All 9 dogs received saline alone (no pharmacologic intervention) during coronary occlusion and the initial XI minutes of reflow; that is, n = 9 at 30