REVIEW ARTICLE
Atrioventricular Plane Displacement and Left Ventricular Function Mahbubul Alam, MD, PhD, and Gunnar Rosenhamer, MD, PhD, Stockholm, Sweden
The assessment of left ventricular (LV) systolic function requires a knowledge of the pumping pattern of the ventricle. Although the function of the longitudinally and circumferentially oriented myocardial fibers in the production of a coordinated contraction has been the subject of anatomic and physiologic studies for many decades, 1·2 the LV pump function is frequently described as mainly being the effect of the contraction of circumferential fibers. 3'9 Recent studies, however, are pointing to the importance of the function of the longitudinal fibers as well. 10-15 The outer cardiac silhouette changes very little during the cardiac cycle, 13·16·17 and the major changes occur intracardially as a result of the movement of the atrioventricular (AV) plane. The observation 13·18 -20 that the epicardial site of the apex remains virtually immobile during the cardiac cycle has probably contributed to this notion. This way of pumping the blood without much displacement of the intrathoracic structures surrounding the heart should be physiologically useful in minimizing the heart's energy expenditure during the cardiac cycle. Contraction of the longitudinal fibers causes shortening of the LV chamber along its longitudinal axis and movement of the AV plane toward the apex in systole. The descent of the AV plane begins during the isovolumetric contraction phase of systole.13·19·21-23 This motion is not confined to this preejection period (as proposed by Rushmer et al. )4-9 but continues up to the completion of ejection when the major displacement occurs. 13·19·21 ·22·24 In addition to a stationary apex, the left ventricle displays only a slight rotation around its major axis during the cardiac cycle. 18·19·25·26 Therefore, the distance traveled by any point in the AV plane in the apical direction should not only reflect the extent to which the lonFrom the Department of Cardiology, Karolinska Institute at South Hospital (Sodersjukhuset). Reprint requests: Mahbubul Alam, MD, PhD, Department of Cardiology, South Hospital (Sodersjukhuset), S-ll8 83 Stockholm, Sweden. 27/1137748
gitudinal fibers contract, but should also be representative of the function of the whole ventricle. During recent years, we have elaborated in our laboratory a reproducible method for the measurement of AV plane movement in the apical direction and explored its validity as a measure of LV function at rest and immediately after exercise. In addition to our studies, the motion of the mitral ring during the cardiac cycle has been described earlier in both animals and human beings.* Several names have been proposed for this motion: AV plane displacement, 10-13·24·33 ·34 descent of the base, 15 or mitral annulus motion or excursion.14·21·22·26·35 The present article reviews studies characterizing the AV plane displacement on the echocardiogram in normal and diseased states and studies using the AV plane displacement as a measure of LV function. METHODS OF RECORDING THE AV PLANE DISPlACEMENT
The AV plane displacement has been recorded by means of contrast ventriculography, 30·31 radioisotope angiography, 13 echocardiography, 10•13·15·24 and magnetic resonance imaging. 36 Being inexpensive, easy to use, noninvasive, devoid of radiation, and having no influence on the patient's hemodynamic status, echocardiography has become a standard method for assessing LV function, particularly when serial studies are needed. The method of recording the AV plane displacement with either one or two simultaneous M-mode cursors in two-dimensional echocardiographic apical four- and two-chamber views has been described in detail in studies from our laboratory. 10· 12·24·33·34 Briefly, in the apical four-chamber view theM-mode cursor is placed in such a way that the AV plane at the ventricular septum moves among theM-mode line and the magnitude of the displacement toward the apex during systole is recorded on theM-mode tracing. By moving theM-mode line to *References 13-15, 17, 21, 22, 26-32.
427
428
Journal of the American Society of Echocardiography
Alam and Rosenhamer
''1''''1' 11 '1'' 11 1''''1''''1''''1""1"''1'"'1''"1'''1''''1'"1"'
l
l
) 111 1111 1111 11
ul 1111 l 1111 11 , , ,1, 1 ttlttttltttlltttt!ttttlttltlttttlttttlttltlttttllttllt•ulttttlttulutlltttlltutluttltutlt•t•l• 111
A four-chamber view of the heart showing two sites of the atrioventricular (AV) plane; septal (AV-S) and lateral (AV-L). An M-mode cursor is placed at the septal border of the AV plane. The systolic displacement of the AV plane is shown on the right side.
Figure 1
the lateral border of the AV plane, the displacement at the LV lateral wall has also been recorded. The displacements at the anterior and posterior walls of the left ventricle are recorded similarly from the apical two-chamber view. The displacement of the AV plane at the respective walls is measured, using the leading edge of the echoes, from the lowest to the highest point of motion during systole as shown in Figure l. Each AV plane displacement is taken to represent the regional systolic function of the respective wall. A mean value of the AV plane displacement, expressed in mm, is calculated for the above four sites and is used to represent the global function. By use of the M-mode, the recording of the AV plane displacement at one site (septum) was described earlier by Zaky et al./2 and at two sites (septum and lateral wall) by Lundback. 13 In addition, the AV plane displacement can be recorded from the apical four- and two-chamber views by calculating the distance traveled by the midmitral annular plane between end diastole and end systole, as recorded on frozen images. 15•18 Using only the four-chamber view, Pai et al. 14 have recently described the displacement of the septal and lateral walls by measuring the distance between the end-diastolic and end-systolic positions of the mitral annulus.
REPRODUCIBILI1Y OF mE MEmOD
To test the reproducibility of the method for recording AV plane displacement, 19 consecutive subjects (8 healthy subjects and l l patients with myocardial infarction) were studied four times by two different investigators on two different occasions. On each occasion both of the investigators made a separate recording of one of the AV plane sites on the left ventricle (lateral wall). Both investigators were well trained in echocardiography. One of them had considerable routine experience in recording the AV plane displacement (investigator I) and the other had little experience with this measurement (investigator II). The recordings of the AV plane displacement were then analyzed blindly for interobserver and intraobserver variability by use of analysis of variance. On the basis of four different investigations, the intraobserver and interobserver variations were found to be low ( < l mm for both). When separate intraobserver variability tests were performed for two different investigators, a low value was obtained for both investigator I (0.6 mm) and II (l.l mm). In conformity with our findings, other recent studies have also found a low interobserver and intraobserver variation in recordings and mea-
Volume 5 Number 4 July-August 1992
surements of AV plane displacement by vanous methods. 14,15,37
AV PLANE DISPLACEMENT IN VARIOUS CONDITIONS
Healthy Subjects
The AV plane displacement at different sites of the left ventricle was of similar magnitude in healthy subjects (Table 1). 10- 12•24•33•34 The average value for the four sites ranged between 14 mm and 15 mm, the mean age of the subjects being 57 to 60 years. None of these subjects had an AV plane displacement of less than 10 mm. When separate analyses were made for the quantification of AV plane displacement in healthy subjects24 of two age groups (mean ages 28 and 60 years), a significantly higher value (p < 0.001) was obtained in the younger group (17.5 mm) than in the older group (15 mm). The correlation between age and the magnitude of AV plane displacement was weak but highly significant (r = -0.58, p < 0.001). Conversely, there was no significant difference in fractional shortening between the groups. In a study by Hammarstrom et al., 37 contrary to our results, the displacement at the lateral LV wall was found to be greater than the displacement at the septum. The number of subjects in this study was considerably smaller, however, than in ours. Using the distance between the midmitral annular plane at end diastole and end systole, Simonson et al. 15 found an AV plane displacement of 12 mm in a group of subjects with a mean age of 31 years. All the subjects had an AV plane displacement of 8 mm or more in the study by Simonson and Schiller. 15 The lower values in this study (compared with ours) may be the result of the different method of recording the AV plane displacement. Patients with Acute Myocardial Infarction
Patients with first-time acute myocardial infarction (MI) examined before discharge from the hospital were compared with healthy subjects matched for heart rate, blood pressure, and age. 12•34 The displacement of the AV plane was significantly reduced in both anterior and inferior MI at all the recorded sites (i.e., the septal, anterior, lateral, and posterior LV walls) compared with that of healthy individuals. The reduced displacement was more marked at the sites of infarction (i.e. anterior and septal sites in cases of anterior MI and the posterior site in inferior infarcts) (Table 1). When the patients were divided into two
AV plane displacement and LV function 429
Table 1 Magnitude of AV plane displacement in different groups of patients observed in our studies. 10•12•24•27 Results are in either means or medians Type of patients
Healthy subjects (n = 24) Anterior MI (n = 21) Inferior MI (n = 16) AP without MI (n = 48) Chronic CHF (n = 70)
AV-S (mm)
14.5
AV-A (mm)
15
AV-L (mm)
AV-P (mm)
15
15
AV-mean (mm)
15
8.4
7.6
10
11.1
9.3
10.4
12.8
13
9.2
11.4
14
14.5
15
5
5.4
6.2
15 5.7
14.5 5.6
AP, Angina pectoris; AV-A, AV plane displacement at anterior wall; AVL, AV plane displacement at lateral wall; AV-P, AV plane displacement at posterior wall; AV-S, AV plane displacement at septum; AV-mean, mean value of AV plane displacement; CHF, congestive heart failure; MI, myocardia! infarction.
groups with respect to an isotope-angiographic ejection fraction below or above 50%, we found that a mean AV plane displacement of ~10 mm had high sensitivity (95%) and specificity (82%) in predicting a preserved global function (ejection fraction ~50%). Using the echocardiographic ejection fraction as a reference and taking a midannular plane displacement of 8 mm or more as the cutoff point, Simonson and Schiller15 also found a high sensitivity and specificity in predicting preserved LV global function in a group of patients with different diagnoses. Patients with Chronic Congestive Heart Failure
Patients with severe chronic congestive heart failure 10 caused by previous MI or dilated cardiomyopathy and belonging to New York Heart Association functional class III or IV showed a highly significant reduction of AV plane displacement at all the sites compared with age-matched controls (Table 1). A mean value of the AV plane displacement of
Atrioventricular Plane Displacement and Left Ventricular Function Mahbubul Alam, MD, PhD, and Gunnar Rosenhamer, MD, PhD, Stockholm, Sweden
The assessment of left ventricular (LV) systolic function requires a knowledge of the pumping pattern of the ventricle. Although the function of the longitudinally and circumferentially oriented myocardial fibers in the production of a coordinated contraction has been the subject of anatomic and physiologic studies for many decades, 1·2 the LV pump function is frequently described as mainly being the effect of the contraction of circumferential fibers. 3'9 Recent studies, however, are pointing to the importance of the function of the longitudinal fibers as well. 10-15 The outer cardiac silhouette changes very little during the cardiac cycle, 13·16·17 and the major changes occur intracardially as a result of the movement of the atrioventricular (AV) plane. The observation 13·18 -20 that the epicardial site of the apex remains virtually immobile during the cardiac cycle has probably contributed to this notion. This way of pumping the blood without much displacement of the intrathoracic structures surrounding the heart should be physiologically useful in minimizing the heart's energy expenditure during the cardiac cycle. Contraction of the longitudinal fibers causes shortening of the LV chamber along its longitudinal axis and movement of the AV plane toward the apex in systole. The descent of the AV plane begins during the isovolumetric contraction phase of systole.13·19·21-23 This motion is not confined to this preejection period (as proposed by Rushmer et al. )4-9 but continues up to the completion of ejection when the major displacement occurs. 13·19·21 ·22·24 In addition to a stationary apex, the left ventricle displays only a slight rotation around its major axis during the cardiac cycle. 18·19·25·26 Therefore, the distance traveled by any point in the AV plane in the apical direction should not only reflect the extent to which the lonFrom the Department of Cardiology, Karolinska Institute at South Hospital (Sodersjukhuset). Reprint requests: Mahbubul Alam, MD, PhD, Department of Cardiology, South Hospital (Sodersjukhuset), S-ll8 83 Stockholm, Sweden. 27/1137748
gitudinal fibers contract, but should also be representative of the function of the whole ventricle. During recent years, we have elaborated in our laboratory a reproducible method for the measurement of AV plane movement in the apical direction and explored its validity as a measure of LV function at rest and immediately after exercise. In addition to our studies, the motion of the mitral ring during the cardiac cycle has been described earlier in both animals and human beings.* Several names have been proposed for this motion: AV plane displacement, 10-13·24·33 ·34 descent of the base, 15 or mitral annulus motion or excursion.14·21·22·26·35 The present article reviews studies characterizing the AV plane displacement on the echocardiogram in normal and diseased states and studies using the AV plane displacement as a measure of LV function. METHODS OF RECORDING THE AV PLANE DISPlACEMENT
The AV plane displacement has been recorded by means of contrast ventriculography, 30·31 radioisotope angiography, 13 echocardiography, 10•13·15·24 and magnetic resonance imaging. 36 Being inexpensive, easy to use, noninvasive, devoid of radiation, and having no influence on the patient's hemodynamic status, echocardiography has become a standard method for assessing LV function, particularly when serial studies are needed. The method of recording the AV plane displacement with either one or two simultaneous M-mode cursors in two-dimensional echocardiographic apical four- and two-chamber views has been described in detail in studies from our laboratory. 10· 12·24·33·34 Briefly, in the apical four-chamber view theM-mode cursor is placed in such a way that the AV plane at the ventricular septum moves among theM-mode line and the magnitude of the displacement toward the apex during systole is recorded on theM-mode tracing. By moving theM-mode line to *References 13-15, 17, 21, 22, 26-32.
427
428
Journal of the American Society of Echocardiography
Alam and Rosenhamer
''1''''1' 11 '1'' 11 1''''1''''1''''1""1"''1'"'1''"1'''1''''1'"1"'
l
l
) 111 1111 1111 11
ul 1111 l 1111 11 , , ,1, 1 ttlttttltttlltttt!ttttlttltlttttlttttlttltlttttllttllt•ulttttlttulutlltttlltutluttltutlt•t•l• 111
A four-chamber view of the heart showing two sites of the atrioventricular (AV) plane; septal (AV-S) and lateral (AV-L). An M-mode cursor is placed at the septal border of the AV plane. The systolic displacement of the AV plane is shown on the right side.
Figure 1
the lateral border of the AV plane, the displacement at the LV lateral wall has also been recorded. The displacements at the anterior and posterior walls of the left ventricle are recorded similarly from the apical two-chamber view. The displacement of the AV plane at the respective walls is measured, using the leading edge of the echoes, from the lowest to the highest point of motion during systole as shown in Figure l. Each AV plane displacement is taken to represent the regional systolic function of the respective wall. A mean value of the AV plane displacement, expressed in mm, is calculated for the above four sites and is used to represent the global function. By use of the M-mode, the recording of the AV plane displacement at one site (septum) was described earlier by Zaky et al./2 and at two sites (septum and lateral wall) by Lundback. 13 In addition, the AV plane displacement can be recorded from the apical four- and two-chamber views by calculating the distance traveled by the midmitral annular plane between end diastole and end systole, as recorded on frozen images. 15•18 Using only the four-chamber view, Pai et al. 14 have recently described the displacement of the septal and lateral walls by measuring the distance between the end-diastolic and end-systolic positions of the mitral annulus.
REPRODUCIBILI1Y OF mE MEmOD
To test the reproducibility of the method for recording AV plane displacement, 19 consecutive subjects (8 healthy subjects and l l patients with myocardial infarction) were studied four times by two different investigators on two different occasions. On each occasion both of the investigators made a separate recording of one of the AV plane sites on the left ventricle (lateral wall). Both investigators were well trained in echocardiography. One of them had considerable routine experience in recording the AV plane displacement (investigator I) and the other had little experience with this measurement (investigator II). The recordings of the AV plane displacement were then analyzed blindly for interobserver and intraobserver variability by use of analysis of variance. On the basis of four different investigations, the intraobserver and interobserver variations were found to be low ( < l mm for both). When separate intraobserver variability tests were performed for two different investigators, a low value was obtained for both investigator I (0.6 mm) and II (l.l mm). In conformity with our findings, other recent studies have also found a low interobserver and intraobserver variation in recordings and mea-
Volume 5 Number 4 July-August 1992
surements of AV plane displacement by vanous methods. 14,15,37
AV PLANE DISPLACEMENT IN VARIOUS CONDITIONS
Healthy Subjects
The AV plane displacement at different sites of the left ventricle was of similar magnitude in healthy subjects (Table 1). 10- 12•24•33•34 The average value for the four sites ranged between 14 mm and 15 mm, the mean age of the subjects being 57 to 60 years. None of these subjects had an AV plane displacement of less than 10 mm. When separate analyses were made for the quantification of AV plane displacement in healthy subjects24 of two age groups (mean ages 28 and 60 years), a significantly higher value (p < 0.001) was obtained in the younger group (17.5 mm) than in the older group (15 mm). The correlation between age and the magnitude of AV plane displacement was weak but highly significant (r = -0.58, p < 0.001). Conversely, there was no significant difference in fractional shortening between the groups. In a study by Hammarstrom et al., 37 contrary to our results, the displacement at the lateral LV wall was found to be greater than the displacement at the septum. The number of subjects in this study was considerably smaller, however, than in ours. Using the distance between the midmitral annular plane at end diastole and end systole, Simonson et al. 15 found an AV plane displacement of 12 mm in a group of subjects with a mean age of 31 years. All the subjects had an AV plane displacement of 8 mm or more in the study by Simonson and Schiller. 15 The lower values in this study (compared with ours) may be the result of the different method of recording the AV plane displacement. Patients with Acute Myocardial Infarction
Patients with first-time acute myocardial infarction (MI) examined before discharge from the hospital were compared with healthy subjects matched for heart rate, blood pressure, and age. 12•34 The displacement of the AV plane was significantly reduced in both anterior and inferior MI at all the recorded sites (i.e., the septal, anterior, lateral, and posterior LV walls) compared with that of healthy individuals. The reduced displacement was more marked at the sites of infarction (i.e. anterior and septal sites in cases of anterior MI and the posterior site in inferior infarcts) (Table 1). When the patients were divided into two
AV plane displacement and LV function 429
Table 1 Magnitude of AV plane displacement in different groups of patients observed in our studies. 10•12•24•27 Results are in either means or medians Type of patients
Healthy subjects (n = 24) Anterior MI (n = 21) Inferior MI (n = 16) AP without MI (n = 48) Chronic CHF (n = 70)
AV-S (mm)
14.5
AV-A (mm)
15
AV-L (mm)
AV-P (mm)
15
15
AV-mean (mm)
15
8.4
7.6
10
11.1
9.3
10.4
12.8
13
9.2
11.4
14
14.5
15
5
5.4
6.2
15 5.7
14.5 5.6
AP, Angina pectoris; AV-A, AV plane displacement at anterior wall; AVL, AV plane displacement at lateral wall; AV-P, AV plane displacement at posterior wall; AV-S, AV plane displacement at septum; AV-mean, mean value of AV plane displacement; CHF, congestive heart failure; MI, myocardia! infarction.
groups with respect to an isotope-angiographic ejection fraction below or above 50%, we found that a mean AV plane displacement of ~10 mm had high sensitivity (95%) and specificity (82%) in predicting a preserved global function (ejection fraction ~50%). Using the echocardiographic ejection fraction as a reference and taking a midannular plane displacement of 8 mm or more as the cutoff point, Simonson and Schiller15 also found a high sensitivity and specificity in predicting preserved LV global function in a group of patients with different diagnoses. Patients with Chronic Congestive Heart Failure
Patients with severe chronic congestive heart failure 10 caused by previous MI or dilated cardiomyopathy and belonging to New York Heart Association functional class III or IV showed a highly significant reduction of AV plane displacement at all the sites compared with age-matched controls (Table 1). A mean value of the AV plane displacement of
