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Mitral Annular Disjunction in Advanced Myxomatous Mitral Valve Disease: Echocardiographic Detection and Surgical Correction
Mitral Annular Disjunction in Advanced Myxomatous Mitral Valve Disease: Echocardiographic Detection and Surgical Correction Maria J. Eriksson, MD, PhD, Catarina Y. Bitkover, MD, PhD, Ahmad S. Omran, MD, Tirone E. David, MD, Joan Ivanov, PhD, Mohamed J. Ali, MD, Anna Woo, MD, Samuel C. Siu, MD, and Harry Rakowski, MD, Toronto, Ontario, Canada
Mitral annular disjunction is a structural abnormality of the mitral annulus fibrosus described by pathologists in association with mitral leaflet prolapse and defined as a separation between the atrial wall– mitral valve (MV) junction and the left ventricular attachment allowing for hypermobility of the MV apparatus. The transesophageal echocardiographic characteristics of this abnormality have not been previously described. In patients undergoing MV repair for myxomatous MV degeneration and evaluated using a standardized transesophageal echocardiographic protocol, annular disjunction (mean value 10 ⴞ 3 mm) was seen at the base of the posterior leaflet in 98% of patients with advanced,
Mitral valve (MV) prolapse is a relatively common
disorder and may cause mitral regurgitation (MR) requiring operation.1 Recent studies have demonstrated excellent long-term outcomes in patients undergoing MV repair, which has gained acceptance as the surgical treatment of choice in patients with severe MR caused by prolapse or flail leaflets.2-7 Less favorable long-term results of MV repair, with an increased risk for reoperation, have been reported for patients with advanced myxomatous MV degeneration (MVD).4,7,8 The purpose of MV repair is to correct leaflet redundancy, elongation, and/or rupture of chordae From the Divisions of Cardiology (M. J. E., A. S. O., A. W., S. C. S., and H. R.), and Cardiovascular Surgery (C. Y. B., T. E. D., J. I., and M. J. A.), Toronto General Hospital, University Health Network. Presented as an abstract at the American Heart Association Scientific Session in Anaheim, Calif, November 12, 2001. Supported in part by the Hypertrophic Cardiomyopathy Research Fund, University of Toronto, and the Swedish Heart and Lung Foundation (200041256), Stockholm (Dr Eriksson). Reprint requests: Harry Rakowski, MD, Division of Cardiology, Toronto General Hospital, 12EN-212, 200 Elizabeth St, Toronto, Ontario M5G 2C4, Canada (E-mail: harry.rakowski@ uhn.on.ca). 0894-7317/$30.00 Copyright 2005 by the American Society of Echocardiography. doi:10.1016/j.echo.2005.06.013
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and in 9% of patients with mild/moderate MV degeneration. There was a significant correlation between the magnitude of disjunction and the number of segments with prolapse/flail (r ⴝ 0.397, P ⴝ .001). We found annular disjunction to be a common component of MV apparatus in advanced MV degeneration. Its recognition on transesophageal echocardiography is important to facilitate optimal MV repair. The modification of the repair technique allows surgical correction of the annular disjunction, which seems to optimize long-term results in these challenging cases. (J Am Soc Echocardiogr 2005;18:1014-1022.)
tendineae, and dilatation of the mitral annulus. Geometric restoration of mitral annulus by annuloplasty has been shown to be important for the long-term durability of MV repair.5,6 Although dilatation is the most common abnormality of the mitral annulus fibrosus, the structure of the annulus itself can vary in different patients. Hutchins et al,9 in their study of 900 autopsied hearts, observed a disjunction of the mitral annulus in hearts with MV prolapse. They defined disjunction as a separation between atrial wall–MV junction and the left ventricular (LV) attachment (Figures 1 and 2). The mitral annulus is an integral part of the MV along with left atrial (LA) and LV coupling. Previous studies have demonstrated that the normal mitral annulus has a complex, nonplanar shape and function, best assessed using 3-dimensional imaging techniques.10-16 In the horizontal plane the normal annulus is elliptic in shape with a long and a short axis. The ratio between these two axes has been previously used as a measure of annular eccentricity.17 The normal annular function can be characterized by systolic annular area reduction, which may improve leaflet coaptation and normal MV closure.16,18,19 Because we have observed annular disjunction on direct inspection at operation in some patients with advanced MVD, we sought to describe the mitral annular structure and function in this particular subgroup of patients studied
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analysis of the intraoperative TEE was performed in 67 patients with advanced MVD. For comparison, intraoperative TEE from a subgroup of 32 patients with mild/ moderate MVD were analyzed. All patients provided written informed consent for the study. The study was approved by the research ethics board. TEE Examination
Figure 1 Intraoperative picture of posterior annular disjunction. Posterior mitral leaflet (PML) is detached from annulus and area of disjunction is seen between arrows.
by standardized, intraoperative, multiplane transesophageal echocardiography (TEE). Furthermore, a modified MV repair technique for this group of patients has been developed to correct this abnormality.
METHODS Study Population Between January 1995 and December 1999, 383 patients underwent MV repair by one experienced cardiac surgeon (T. E. D.). Myxomatous MVD of various degrees was the underlying MV pathology in 287 of 383 (75%) of these patients. In all patients, the degree of MVD was classified by careful intraoperative inspection and histopathologic analysis of the MV. Advanced MVD was defined by: (1) intraoperative findings of marked generalized increase in the MV thickness and volume of both leaflets, and hooding or parachute changes of the free edge of the valve with gross dilatation of the mitral annulus; and (2) diffuse histopathologic alternations of the valve tissue including expansion of the spongiosa layer, accumulation of acid mucopolysaccharides, and focal disruption of the fibrosa layer found on pathologic analysis of MV specimens. The degree of the myxomatous process was classified intraoperatively by the surgeon (T. E. D.) as mild if only the prolapsing segment was involved, or moderate if both leaflets displayed some myxomatous changes. Of 287 patients, 67 (23%) were found to have the advanced form of MVD according to the above-mentioned criteria. The remaining 220 patients were classified intraoperatively and on pathologic analysis as having moderate to mild MVD. For the purpose of this study a retrospective
Intraoperative TEE was performed in the operating room by an experienced operator using an imaging system (Sonos 2500 or 5500, Hewlett-Packard Co, Andover, Mass) with a 5-MHz multiplane transducer (OmniPlane, HewlettPackard Co). The TEE probe was placed immediately after the induction of general anesthesia, and a complete examination of the heart was performed. MV pathology was assessed using a systematic approach recently developed by our institution.20 We used a widely accepted classification scheme, originally described by Ranganathan et al21 and popularized by Carpentier et al,22 with the posterior mitral leaflet divided into 3 scallops: anterolateral, middle (P2), and posterolateral. The anterior leaflet was divided into 3 juxtaposed segments: anterior, middle (A2), and posterior.22 The number of prolapsed or flail segments was recorded prospectively for every patient. An experienced echocardiographer reviewed all TEE recordings and performed detailed offline measurements of mitral annular dimensions without knowledge of the surgeon’s classification of the degree of MV disease. The annular disjunction was present if there was a separation between the P2 insertion into the LA wall and the atrial/ventricular attachment, according to original description by Hutchins et al.9 An intraoperative photograph and a TEE image of annular disjunction in systole and diastole are shown in Figures 1 and 2, respectively. The measurement of annular disjunction was performed in a 4-chamber (0-degree rotation) midesophageal view as shown in Figure 2. The upper limit of the disjunction was defined at the level of P2 scallop insertion into the LA wall, whereas the lower limit of the disjunction was defined at the level of LA connection with ventricular myocardium (Figure 2). The distance between these two levels was measured as the annular disjunction. The change in echogenecity between the thin annular tissue and ventricular myocardium was helpful in determination of the lower level of annular disjunction. Annular disjunction was calculated as the mean of measurements from 3 consecutive cardiac cycles. For the measurements of annular diameters we used 3 midesophageal views: 4-chamber (0-degree rotation), bicommisural (75-degree rotation), and anteroposterior (135-degree rotation). To study the shape and eccentricity of the annulus in the horizontal plane we compared the diastolic annular diameters in these 3 views. Eccentricity of the annulus was calculated by the ratio between the bicommisural and anteroposterior diastolic diameters. The annular contraction was studied by comparing the diastolic and end-systolic diameters in a 0- and 75-degree
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Figure 2 Schematic diagram (A) and transesophageal echocardiographic image of mitral valve (in systole [B] and diastole [C]) with bileaflet prolapse and posterior annular disjunction. Measurements of mitral annular diameters and disjunction in systole: presumed original annulus– diameter 1 (dotted line); displaced annulus– diameter 2 (dotted line); annular disjunction– between arrows (solid line). A2, Middle segment of anterior mitral segment; LA, left atrium; LV, left ventricle; P2, middle scallop of posterior mitral leaflet. rotation views. The diastolic diameters were measured late in diastole at the P wave. To study the influence of annular disjunction on annular dimensions, the diameters of the original and displaced annulus were taken in systole in a 4-chamber (0-degree rotation) view. We measured the presumed original annulus and the displaced annulus as shown in Figure 2. Both were measured from the hinge point at the base of the A2 segment at the aortic apparatus to the upper level of the LV myocardium (original annulus) and to the point of the P2 scallop insertion into the LA wall (displaced annulus), respectively. The thickness of the mitral leaflets was measured in systole. The LV was visualized in the transgastric short-axis view and the anteroposterior, end-diastolic, and endsystolic LV dimensions were measured at the level of the papillary muscles. All measurements were obtained from 3 consecutive heart cycles and presented as a mean value. LV systolic function was also visually assessed as either normal (ejection fraction [EF] ⱖ 60%), mildly reduced (EF 40%-59%), moderately reduced (EF 20%-39%), or severely reduced (EF ⬍ 20%).20,23 The severity of MR was assessed from color Doppler information and pulmonary venous flow pattern as recently described in detail.20,24-26 MR was classified as trivial, mild, moderate, and severe,20 and the number of regurgitant jets was noted. Interobserver and intraobserver variability for annular disjunction, and annular diameter 1 and 2 in systole was assessed in randomly chosen subset of 20 of the 67 patients by two experienced echocardiographers (M. J. E. and M. J. A.). Comparison between Advanced and Mild/Moderate MVD The last 32 consecutive patients with the advanced form of MVD were compared with an age- and sex-matched group (n ⫽ 32) recruited from the remaining 220 patients with MV repair and mild/moderate MVD, undergoing
operation approximately during the same period of time. The comparison group underwent MV repair by the same surgeon (T. E. D.) between January 1995 and December 1999, and had an intraoperative multiplane TEE examination performed by the same echocardiographer, using the same standardized protocol for the evaluation of the MV pathology as did the study population.20 The TEE studies were reviewed in the same way for the patients with advanced and mild/moderate MVD, by the same echocardiographer, blinded to the surgeon’s classification of the degree of MVD. Operative Technique All patients underwent MV repair. Between 1995 and 1997 previously established and described techniques were used.4,7 In 1998 the repair technique was modified to address the issue of mitral annular disjunction. In the 31 patients operated on after January 1, 1998, most of the posterior leaflet was detached from the mitral annulus. The annulus was repaired using multiple horizontal mattress sutures, which were passed through the ventricular endocardium and displaced annulus. Next, the prolapsing segment (eg, P2) was resected, and all chordae tendineae attached to the ventricular surface of the remaining posterior leaflet were excised, leaving only the chordae attached to the free margin. The posterior leaflet was trimmed to a height of approximately 10 mm, and then reattached to the endocardium of the LV where the previous suture had been placed. Any remaining prolapsing segments of the posterior or anterior leaflet were corrected with artificial chordae of expanded polytetrafluoroethylene sutures. An annuloplasty ring or band was used in all cases to reduce the area of the mitral annulus to approximately that of the anterior leaflet. Clinical Follow-up All study patients were followed up by the referring cardiologist and annually contacted by our research personnel until October 2004. Postoperative events were
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Table 1 Clinical profile, operative data, and echocardiographic variables on 67 patients with advanced myxomatous mitral valve disease Variables
Mean age, y Male sex, n (%) NYHA functional class I/II/III/IV, n (%) LV systolic function, grade I/II/III-IV, n (%) Preoperative atrial fibrillation, n (%) Coronary artery bypass grafting, n (%) Cardiopulmonary bypass time, min Cross-clamp time, min Echocardiographic variables Annular disjunction, mm Mitral valve thickness, mm LV end-diastolic diameter, mm LA systolic diameter, mm MR grade I/II/III/IV, n Number of MR jets
52 ⫾ 14 44 (66%) 16 (23%)/25 (38%)/22 (33%)/4 (6%) 33 (49%)/29 (43%)/5 (8%) 16 (23%) 2 (3%) 97 ⫾ 31 81 ⫾ 30 10 ⫾ 3 4.1 ⫾ 0.9 60 ⫾ 8 56 ⫾ 7 0/6/27/34 2.3 ⫾ 0.9
LA, left atrial; LV, left ventricular; MR, mitral regurgitation; NYHA, New York Heart Association. Continuous variables described as mean ⫾SD.
compiled and analyzed according to the Guidelines for Reporting Morbidity and Mortality after Cardiac Valvular Operations.27 The follow-up was complete with regard to mortality and reoperations. Statistical Analysis Software (SPSS for Windows, Version 10, SPSS Inc, Chicago, Ill) was used for all statistical analyses. Continuous data are presented as mean ⫾ 1SD in text and tables. Comparisons were performed using Student paired t test or analysis of variance for continuous data, and Fisher’s exact test or the 2 test for categorical variables, where appropriate. Pearson’s correlation coefficient was used to evaluate the relationships between echocardiographic variables. Intraobserver and interobserver variability was assessed by the Bland-Altman method and by coefficient of variation (percent), calculated by dividing the SD of the difference between two measurements by the mean value of the measurements, multiplied by 100. Longitudinal data were analyzed by the Kaplan-Meier methods and survival estimates were compared using log-rank test. A P value less than .05 was considered significant.
RESULTS Table 1 shows the clinical and TEE characteristics and the preoperative and operative data of the 67 patients with advanced MVD. All patients had multisegment involvement, with 2 segments in 9 patients, 3 segments in 20 patients, and more than 3 segments in 38 patients. The midportions of both mitral leaflets, A2 and P2, were involved in 65 of 67 patients. The flail originated from the P2 scallop in 26 patients and from the A2 segment in 7 patients. Annular disjunction at the base of the P2 scallop (Figure 2) was seen in 66 of 67 patients. In one
Figure 3 Relationship between magnitude of annular disjunction and number of segments with prolapse/flail (P ⬍ .05 by analysis of variance).
patient with P2, posterior segment of anterior leaflet prolapse, and A2 flail, the annular disjunction could not be seen in the 0-degree midesophageal TEE view. The mean value of annular disjunction was 10 ⫾ 3 mm and was significantly greater for patients with a larger number of MV segments with prolapse or flail (P ⫽ .011 by analysis of variance). There was also a significant correlation between the magnitude of the disjunction and the number of diseased segments (r ⫽ 0.397, P ⫽ .001) (Figure 3). There was no significant difference between mitral annular dimensions in 3 different TEE views (Figure 4). The mean value for the eccentricity ratio between the bicommisural (43.6 ⫾ 4.6 mm) and anteroposterior (44.0 ⫾ 4.6 mm) diameter was 1.0
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coefficients of variation for the same variables were 8.1%, 3.0%, and 3.2%, respectively. Surgical and Clinical Outcome
Figure 4 Diastolic annular diameters in 3 midesophageal transesophageal echocardiographic (TEE) views (P ⬎ .05).
⫾ 0.1, suggesting that the annulus had assumed a round shape. There was no significant change in mitral annular diameters from diastole to end systole, indicating loss of annular contraction. The most recently included 32 of the 67 patients with advanced MVD were compared with 32 ageand sex-matched patients who underwent MV repair for severe MR caused by mild/moderate MVD. There was no significant difference between the two groups of patients with regard to New York Heart Assocation functional class, presence of coronary artery disease, history of endocarditis, LV function or size, or the degree of MR. The comparison of operative and echocardiographic results for the two groups are shown in Table 2. The patients with mild/moderate MVD had in total significantly fewer mitral segments involved. However, the number of flail segments was significantly higher in these patients than in the patients with advanced MVD (72% and 38%, respectively; P ⫽ .011). The annular disjunction was present only in 3 of 32 patients (9%) in the matched group and a mean value for these 3 patients was 8.2 ⫾ 4.7 mm.
Since January 1998, in addition to MV repair, correction of the annular disjunction was performed using a modified surgical technique in 31 patients. There were no operative deaths. Two of the 67 patients developed postoperative low cardiac output syndrome and were treated successfully with standard medications. There were no postoperative complications in the remaining 65 patients. Immediate postoperative TEE showed excellent hemodynamic results with no MR in 19 patients, trace MR in 41 patients, and mild MR in 7 patients. The mean pressure gradient across the repaired MV was 2.2 ⫾ 0.8 mm Hg and MV area was 2.6 ⫾ 0.5 cm2. There was no difference in the early postoperative TEE results in terms of the degree of residual MR between the patients who had operation before and after January 1998. During a follow-up of 5.9 ⫾ 1.6 years there were two noncardiac deaths for patients with advanced MVD, caused by cerebrovascular accident and cerebral atrophy. Three patients required reoperation, for recurrent MR in two and for mitral prolapse in one. In the group of patients with mild/moderate MVD there was one cardiac death caused by congestive heart failure, and one of the patients required MV reoperation. There was no significant difference in overall survival or freedom from reoperation between advanced and mild/moderate MVD groups (93.3 ⫾ 5.2% vs 85.7 ⫾ 13.2%, P ⫽ .5; and 82 ⫾ 12.9% vs 96.9 ⫾ 3.1%, P ⫽ .79, respectively). We compared survival and freedom from reoperation in the patients with advanced MVD who underwent operation before versus after the introduction of the modified MV repair in 1998. At a latest follow-up the survival was 94.7 ⫾ 5.1% in the group operated without and 96.8 ⫾ 3.2% (P ⫽ .28) in the group operated with the modified technique. There was a significant difference in follow-up between the groups (8.6 ⫾ 0.9 vs 6.1 ⫾ 0.7 years, P ⱕ .0001). The freedom from reoperation was 83.3 ⫾ 13.0% and 66.7 ⫾ 27.2%, respectively (P ⫽ .41).
Reproducibility The calculated interobserver coefficients of variation were 6.2% for annular disjunction, 2.9% for the end-systolic diameter of the original annulus, and 3.4% for the displaced annulus, both in 4-chamber view. The Bland-Altman plot shows the interobserver variability for the measurement of annular disjunction (Figure 5). No systematic bias was observed. The corresponding Pearson’s correlation coefficients were: r ⫽ 0.98 and P less than .001 for annular disjunction; r ⫽ 0.98 and P less than .001 for the original annulus; and r ⫽ 0.97 and P less than .001 for the displaced annulus. The intraobserver
DISCUSSION This study is the first, to our knowledge, to describe the echocardiographic recognition of disjunction of the posterior mitral annulus in patients with advanced MVD with bileaflet prolapse. This histopathologic abnormality was first reported by Hutchins et al9 in 1986. In their study of 900 autopsied adult hearts they noted this mitral annular abnormality in 23 of 25 hearts with floppy MVs. They described this entity as disjunction of the
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Table 2 Clinical and echocardiographic data on 32 patients with advanced and 32 patients with mild/moderate myxomatous mitral valve disease Mean age, y NYHA functional class, I and II/III and IV, n (%) LV systolic function, grade I/II-IV, n (%) Coronary artery bypass grafting, n (%) History of infective endocarditis, n (%) Cardiopulmonary bypass time, min Cross-clamp time, min LA systolic diameter, mm Mitral annulus 1*, 0-degree end systole, mm Mitral annulus 1*, 75-degree end systole, mm Mitral annulus 2, 0-degree diasatole, mm Mitral annulus 2, 75-degree diastole, mm Annular disjunction n (%) Prolapse/flail ⱖ 3 segments, n (%) Flail segments, n (%) Mitral valve thickness, mm LV end-diastolic diameter, mm LV end-systolic diameter, mm MR grade Number of MR jets
Advanced MVD
Mild/moderate MVD
P value
54 ⫾ 12 23 (72%)/9 (28%) 20 (63%)/12 (37%) 0/ (0%) 2/ (6%) 84 ⫾ 22 69 ⫾ 21 56 ⫾ 8 44 ⫾ 5 43 ⫾ 4 45 ⫾ 5 43 ⫾ 5 31/ (97%) 24/ (75%) 12/ (38%) 4.2 ⫾ 1.0 58 ⫾ 7 39 ⫾ 6 3.4 ⫾ 0.6 2.6 ⫾ 1.0
54 ⫾ 12 20 (63%)/12 (37%) 20 (63%)/12 (37%) 3/ (9%) 6/ (19%) 79 ⫾ 24 64 ⫾ 22 48 ⫾ 4 38 ⫾ 5 39 ⫾ 6 40 ⫾ 5 42 ⫾ 5 3/ (9%) 1/ (3%) 23/ (72%) 2.8 ⫾ 0.7 60 ⫾ 6 39 ⫾ 8 3.6 ⫾ 0.5 1.4 ⫾ 0.5
.28 .59 1.0 .24 .26 .43 .55 ⬍.0001 ⬍.0001 .003 ⬍.0001 .7 ⬍.0001 ⬍.0001 .011 ⬍.0001 .40 .92 .18 ⬍.0001
LA, left atrial; LV, left ventricular; MR, mitral regurgitation; MVD, myxomatous mitral valve degneration; NYHA, New York Heart Association. *Mitral annulus 1, at the level of the presumed original annulus; mitral annulus 2, displaced annulus. Continuous variables described as mean ⫾ SD.
Figure 5 Bland-Altman plot showing interobserver variability for measurement of annular disjunction in 20 patients with advanced mitral valve degeneration.
mitral annulus, ie, a separation between the atrial wall–MV junction and the LV attachment. The normal mitral annulus is typically described as a cordlike ring of circumferentially oriented collagen and elastic fibers supporting the leaflets of the MV at the atrioventricular junction.28 In contrast, for patients with disjunction the annulus seems stretched and resembles a curtainlike structure connecting the MV–LA junction and LV myocardium. The disjunction may affect the entire annulus fibrosus, or be limited only to certain segments, particularly their central and medial portions.9,29 Annular disjunction was rare in normal hearts (5.7%) in the study by Hutchins et al.9 However, Angelini et al,29 in their study of 13 autopsied hearts, encountered annular disjunction in a similar number of hearts with floppy as normal valves. Thus, the authors suggested that
this finding was simply a variant of the normal arrangement of the mitral annulus. Our results are similar to that reported by Hutchins et al.9 We observed annular disjunction in 99% of patients with advanced MVD and in only 9% of our control group. Furthermore, there was a positive correlation between the magnitude of annular disjunction and the number of diseased MV segments (prolapse or flail) in our study. Although the functional implications of annular disjunction are not entirely understood, it seems probable that there is an association between the disjunction and the severity of MV prolapse/ MVD. Hutchins et al9 hypothesized that disjunction permits hypermobility of the mitral leaflets and, therefore, may play a role in the development of prolapse and myxomatous degeneration of the MV. Recognition of annular disjunction further emphasizes the complexity of pathology of the MV apparatus, especially for patients with advanced MVD. Mitral Annular Function and Shape The functional consequences of annular disjunction may affect the shape and function of the mitral annulus. The normal mitral annulus is an essential part of the MV, and the LA and LV complex. Its physiology has been studied in experimental and clinical settings.10-16 Previous echocardiographic and magnetic resonance studies have demonstrated a complex, nonplanar, saddle-shaped or ski-slope configuration of the normal mitral annulus, which is maintained throughout the cardiac cycle.11-16 In the horizontal plane the normal mitral annulus has an
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elliptic shape, with a ratio between the two axes of 1.25 ⫾ 0.14.17 The decrease in annular eccentricity has been shown to correlate with functional MR.15 In our study there was no significant difference in any of the diameters measured in the different imaging planes with a mean eccentricity ratio of 1.0 ⫾ 0.1, suggesting remodeling of the annulus, with a complete loss of eccentricity in the horizontal plane. The annular function can be characterized by an apicobasal motion in the vertical plane, and annular area reduction in the horizontal plane. The normal annular apicobasal function facilitates LV filling in diastole and is closely linked to the LV systolic function.16,30 A 24% to 36% reduction in the mitral annular area during systole improves leaflet coaptation and normal MV closure.16,18,19 Decreased annular contraction has been shown for patients with dilated cardiomyopathy, functional MR, and MV prolapse.15,16,19,31 We did not observe any significant change in annular diameter from diastole to systole in our patients with advanced MVD. These findings suggest that not only geometry, but also function of mitral annulus, is significantly altered for patients with advanced MVD, with a loss of annular contraction. This may further impair mitral leaflet closure in these patients. TEE Assessment of MV Apparatus MV repair is currently clearly favored over prosthetic replacement for the surgical treatment of MR caused by myxomatous degeneration of the MV.3,4,7 Previous careful studies of MV anatomy21 with significant input from cardiac surgeons22 have resulted in a widely accepted classification of MV leaflets. Leaflet pathology is usually accurately assessed and well understood by echocardiographers.20,32-36 The use of intraoperative TEE in the identification and precise localization of MV lesions and mechanisms of MR has been well established.20,32-36 Indeed, recently published recommendations for standardized TEE evaluation of MV pathology have emphasized the importance of identifying abnormalities in MV leaflets and chordae tendineae.35-37 In contrast, the structural changes of the mitral annulus itself have not been the subject of systematic TEE studies. Multiplane TEE allows the entire circumference of the mitral annulus to be visualized. Therefore, our study suggests that not only annular dimensions but also annular structure should be included in the TEE assessment of the MV apparatus in all patients with myxomatous MV disease. The recognition of annular disjunction may be relevant for the choice of the optimal surgical technique used for the repair. Surgical Considerations We selected patients for our study from a large cohort of 383 patients who underwent MV repair by
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one of the authors (T. E. D.) between January 1995 and December 1999. We chose patients with advanced MVD because this subgroup of patients has previously been identified as having an increased risk factor for late failure.4,7,8 The diagnosis of advanced MVD was based on the gross appearance of the MV leaflets and annulus at operation and on histopathologic examination. Our patients had voluminous, thickened leaflets and a grossly dilated mitral annulus. During operation in areas of annular disjunction, the mitral annulus was found to be posteriorly (ie, atrially) displaced. TEE examination confirmed advanced degenerative process in our study population demonstrating severe MR with multiple jets and a large number of mitral segments with prolapse or flail and dilated annulus. Annular disjunction was a common finding in this specific population both on TEE examination and on direct inspection, although no direct measurements of the disjunction were taken at the time of operation. One possible explanation for an increased failure risk for MV repair for patients with advanced MVD could be an incomplete repair as a result of an unrecognized annular disjunction. One can also speculate that disjunction may play a role in the stability of annuloplasty and durability of the repair. Therefore, we modified our operative technique to correct this abnormality. As shown by our latest follow-up data, the outcome with regard to the survival and the freedom from MV reoperation is excellent for patients who underwent MV repair for advanced MVD, and comparable with the results in the group of patients with less advanced MVD. However, we could not demonstrate any significant difference in survival or freedom from reoperation between the groups operated on before and after the modification of the surgical technique. This is probably a result of a relatively small number of patients and a very small number of events in both groups. There was a significant difference in follow-up time between the groups, which also makes the comparison difficult. Study Limitations Although all patients were prospectively enrolled to undergo an intraoperative multiplane TEE examination using a standardized protocol for the evaluation of the MV and annular pathology, the assessment and measurement of annular disjunction and annular geometry were performed by retrospective analysis of the TEE recordings. The echocardiographer performing the measurements was, however, blinded to the surgeon’s classification of the degree of MVD. The use of 2-dimensional TEE for the evaluation of a complex geometry and function of mitral annulus may be considered a limitation of this study. Recent advances with real-time 3-dimensional echocardiographic imaging provide the ability to track annular
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dimensions in space throughout the cardiac cycle.38 However, for the purpose of the immediate recognition of the mitral annular disjunction, the standardized 2-dimensional TEE provides adequate and accurate information. Our study demonstrated that annular disjunction is common for patients with advanced MVD and is less frequent for patients with less advanced disease. This is a retrospective study in a group of patients with advanced MV pathology operated on by one surgeon; therefore, it may not be possible to generalize the results. The lack of significant difference in survival or freedom from reoperation between advanced and mild/moderate MVD indicates that even patients with advance MV disease might achieve excellent surgical result if abnormalities such as annular displacement are recognized and corrected as previously reported from our institution.4 The original publication by Hutchins et al9 indicated highest prevalence of annular displacement for patients with floppy valves; therefore, the study group has been selected based on intraoperative and histologic criteria describing MV pathology. The comparison group and study group were relatively small, nevertheless our study demonstrated that annular disjunction is common in patients with advanced MVD and is less frequent in patients with less advanced disease. However, further studies with a larger number of patients with various degrees of MVD or no mitral pathology are necessary to establish the true frequency of this annular abnormality in patients with MV prolapse and in the general population. Conclusions Our study provides new insights into the overall function and structural changes of MV apparatus for patients with advanced MVD. We demonstrated that posterior annular disjunction is a common finding and alters the geometry and function of the mitral annulus in these patients. Its recognition on TEE examination is important for the accurate evaluation of the complexity of pathologic changes in the MV and its adjacent structures, and for the choice of the optimal MV repair technique. In addition, the modification of MV repair allows surgical correction of the annular disjunction, which may further optimize long-term results in these challenging cases. REFERENCES 1. Freed LA, Levy D, Levine RA, Larson MG, Evans JC, Fuller DL, et al. Prevalence and clinical outcome of mitral-valve prolapse. N Engl J Med 1999;341:1-7. 2. Carpentier A. Cardiac valve surgery–the ⬙French correction.” J Thorac Cardiovasc Surg 1983;86:323-37. 3. Deloche A, Jebara VA, Relland JY, Chauvaud S, Fabiani JN, Perier P, et al. Valve repair with Carpentier techniques: the second decade. J Thorac Cardiovasc Surg 1990;99:990-1001.
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4. David TE, Ivanov J, Armstrong S, Rakowski H. Late outcomes of mitral valve repair for floppy valves: implications for asymptomatic patients. J Thorac Cardiovasc Surg 2003; 125:1143-52. 5. Cohn LH, Couper GS, Aranki SF, Rizzo RJ, Kinchla NM, Collins JJ Jr. Long-term results of mitral valve reconstruction for regurgitation of the myxomatous mitral valve. J Thorac Cardiovasc Surg 1994;107:143-50. 6. Gillinov AM, Cosgrove DM, Blackstone EH, Diaz R, Arnold JH, Lytle BW, et al. Durability of mitral valve repair for degenerative disease. J Thorac Cardiovasc Surg 1998;116: 734-43. 7. David TE, Omran A, Armstrong S, Sun Z, Ivanov J. Longterm results of mitral valve repair for myxomatous disease with and without chordal replacement with expanded polytetrafluoroethylene sutures. J Thorac Cardiovasc Surg 1998;115: 1279-85. 8. Nakayama M, Yutani C, Imakita M, Ishibashi-Ueda H, Nishida N, Kosakai Y, et al. Recurrent incompetence of repaired floppy mitral valves and the severity of myxomatous degeneration. Surg Today 2000;30:497-502. 9. Hutchins GM, Moore GW, Skoog DK. The association of floppy mitral valve with disjunction of the mitral annulus fibrosus. N Engl J Med 1986;314:535-40. 10. Timek TA, Miller DC. Experimental and clinical assessment of mitral annular area and dynamics: what are we actually measuring? Ann Thorac Surg 2001;72:966-74. 11. Levine RA, Triulzi MO, Harrigan P, Weyman AE. The relationship of mitral annular shape to the diagnosis of mitral valve prolapse. Circulation 1987;75:756-67. 12. Levine RA, Handschumacher MD, Sanfilippo AJ, Hagege AA, Harrigan P, Marshall JE, et al. Three-dimensional echocardiographic reconstruction of the mitral valve, with implications for the diagnosis of mitral valve prolapse. Circulation 1989;80:589-98. 13. Komoda T, Hetzer R, Uyama C, Siniawski H, Maeta H, Rosendahl UP, et al. Mitral annular function assessed by 3D imaging for mitral valve surgery. J Heart Valve Dis 1994;3: 483-90. 14. Pai RG, Tanimoto M, Jintapakorn W, Azevedo J, Pandian NG, Shah PM. Volume-rendered three-dimensional dynamic anatomy of the mitral annulus using a transesophageal echocardiographic technique. J Heart Valve Dis 1995;4:623-7. 15. Kaplan SR, Bashein G, Sheehan FH, Legget ME, Munt B, Li XN, et al. Three-dimensional echocardiographic assessment of annular shape changes in the normal and regurgitant mitral valve. Am Heart J 2000;139:378-87. 16. Flachskampf FA, Chandra S, Gaddipatti A, Levine RA, Weyman AE, Ameling W, et al. Analysis of shape and motion of the mitral annulus in subjects with and without cardiomyopathy by echocardiographic 3-dimensional reconstruction. J Am Soc Echocardiogr 2000;13:277-87. 17. Fyrenius A, Engvall J, Janerot-Sjoberg B. Major and minor axes of the normal mitral annulus. J Heart Valve Dis 2001;10: 146-52. 18. Ormiston JA, Shah PM, Tei C, Wong M. Size and motion of the mitral valve annulus in man, I: a two-dimensional echocardiographic method and findings in normal subjects. Circulation 1981;64:113-20. 19. Yiu SF, Enriquez-Sarano M, Tribouilloy C, Seward JB, Tajik AJ. Determinants of the degree of functional mitral regurgitation in patients with systolic left ventricular dysfunction: a quantitative clinical study. Circulation 2000;102:1400-6.
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20. Omran AS, Woo A, David TE, Feindel CM, Rakowski H, Siu SC. Intraoperative transesophageal echocardiography accurately predicts mitral valve anatomy and suitability for repair. J Am Soc Echocardiogr 2002;15:950-7. 21. Ranganathan N, Lam JH, Wigle ED, Silver MD. Morphology of the human mitral valve, II: the value leaflets. Circulation 1970;41:459-67. 22. Carpentier AF, Lessana A, Relland JY, Belli E, Mihaileanu S, Berrebi AJ, et al. The “physio-ring”: an advanced concept in mitral valve annuloplasty. Ann Thorac Surg 1995;60:117785. 23. Stamm RB, Carabello BA, Mayers DL, Martin RP. Twodimensional echocardiographic measurement of left ventricular ejection fraction: prospective analysis of what constitutes an adequate determination. Am Heart J 1982;104:136-44. 24. Helmcke F, Nanda NC, Hsiung MC, Soto B, Adey CK, Goyal RG, et al. Color Doppler assessment of mitral regurgitation with orthogonal planes. Circulation 1987;75:175-83.
26.
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AN. Quantitative assessment of mitral regurgitation by Doppler color flow imaging: angiographic and hemodynamic correlations. J Am Coll Cardiol 1989;13:585-90. Klein AL, Obarski TP, Stewart WJ, Casale PN, Pearce GL, Husbands K, et al. Transesophageal Doppler echocardiography of pulmonary venous flow: a new marker of mitral regurgitation severity. J Am Coll Cardiol 1991;18:518-26. Edmunds LH Jr, Clark RE, Cohn LH, Grunkemeier GL, Miller DC, Weisel RD. Guidelines for reporting morbidity and mortality after cardiac valvular operations. Eur J Cardiothorac Surg 1996;10:812-6. Ferrans VJ, Rodriguez ER. Ultrastructure of normal heart. In: Silver MD, editor. Cardiovascular pathology. New York: Churchill Livingstone Inc; 1991. p. 85. Angelini A, Ho SY, Anderson RH, Davies MJ, Becker AE. A histological study of the atrioventricular junction in hearts with normal and prolapsed leaflets of the mitral valve. Br Heart J 1988;59:712-6. Alam M, Hoglund C, Thorstrand C, Hellekant C. Hemodynamic significance of the atrioventricular plane displacement
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in patients with coronary artery disease. Eur Heart J 1992;13:194-200. Ormiston JA, Shah PM, Tei C, Wong M. Size and motion of the mitral valve annulus in man, II: abnormalities in mitral valve prolapse. Circulation 1982;65:713-9. Muratori M, Berti M, Doria E, Antona C, Alamanni F, Sisillo E, et al. Transesophageal echocardiography as predictor of mitral valve repair. J Heart Valve Dis 2001;10:65-71. Grewal KS, Malkowski MJ, Kramer CM, Dianzumba S, Reichek N. Multiplane transesophageal echocardiographic identification of the involved scallop in patients with flail mitral valve leaflet: intraoperative correlation. J Am Soc Echocardiogr 1998;11:966-71. Shah PM, Raney AA, Duran CM, Oury JH. Multiplane transesophageal echocardiography: a roadmap for mitral valve repair. J Heart Valve Dis 1999;8:625-9. Foster GP, Isselbacher EM, Rose GA, Torchiana DF, Akins CW, Picard MH. Accurate localization of mitral regurgitant defects using multiplane transesophageal echocardiography. Ann Thorac Surg 1998;65:1025-31. Lambert AS, Miller JP, Merrick SH, Schiller NB, Foster E, Muhiudeen-Russell I, et al. Improved evaluation of the location and mechanism of mitral valve regurgitation with a systematic transesophageal echocardiography examination. Anesth Analg 1999;88:1205-12. Shanewise JS, Cheung AT, Aronson S, Stewart WJ, Weiss RL, Mark JB, et al. ASE/SCA guidelines for performing a comprehensive intraoperative multiplane transesophageal echocardiography examination: recommendations of the American Society of Echocardiography council for intraoperative echocardiography and the Society of Cardiovascular Anesthesiologists task force for certification in perioperative transesophageal echocardiography. J Am Soc Echocardiogr 1999; 12:884-900. Gillinov AM, Cosgrove DM III, Shiota T, Qin J, Tsujino H, Stewart WJ, et al. Cosgrove-Edwards annuloplasty system: midterm results. Ann Thorac Surg 2000;69:717-21.
Mitral annular disjunction is a structural abnormality of the mitral annulus fibrosus described by pathologists in association with mitral leaflet prolapse and defined as a separation between the atrial wall– mitral valve (MV) junction and the left ventricular attachment allowing for hypermobility of the MV apparatus. The transesophageal echocardiographic characteristics of this abnormality have not been previously described. In patients undergoing MV repair for myxomatous MV degeneration and evaluated using a standardized transesophageal echocardiographic protocol, annular disjunction (mean value 10 ⴞ 3 mm) was seen at the base of the posterior leaflet in 98% of patients with advanced,
Mitral valve (MV) prolapse is a relatively common
disorder and may cause mitral regurgitation (MR) requiring operation.1 Recent studies have demonstrated excellent long-term outcomes in patients undergoing MV repair, which has gained acceptance as the surgical treatment of choice in patients with severe MR caused by prolapse or flail leaflets.2-7 Less favorable long-term results of MV repair, with an increased risk for reoperation, have been reported for patients with advanced myxomatous MV degeneration (MVD).4,7,8 The purpose of MV repair is to correct leaflet redundancy, elongation, and/or rupture of chordae From the Divisions of Cardiology (M. J. E., A. S. O., A. W., S. C. S., and H. R.), and Cardiovascular Surgery (C. Y. B., T. E. D., J. I., and M. J. A.), Toronto General Hospital, University Health Network. Presented as an abstract at the American Heart Association Scientific Session in Anaheim, Calif, November 12, 2001. Supported in part by the Hypertrophic Cardiomyopathy Research Fund, University of Toronto, and the Swedish Heart and Lung Foundation (200041256), Stockholm (Dr Eriksson). Reprint requests: Harry Rakowski, MD, Division of Cardiology, Toronto General Hospital, 12EN-212, 200 Elizabeth St, Toronto, Ontario M5G 2C4, Canada (E-mail: harry.rakowski@ uhn.on.ca). 0894-7317/$30.00 Copyright 2005 by the American Society of Echocardiography. doi:10.1016/j.echo.2005.06.013
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and in 9% of patients with mild/moderate MV degeneration. There was a significant correlation between the magnitude of disjunction and the number of segments with prolapse/flail (r ⴝ 0.397, P ⴝ .001). We found annular disjunction to be a common component of MV apparatus in advanced MV degeneration. Its recognition on transesophageal echocardiography is important to facilitate optimal MV repair. The modification of the repair technique allows surgical correction of the annular disjunction, which seems to optimize long-term results in these challenging cases. (J Am Soc Echocardiogr 2005;18:1014-1022.)
tendineae, and dilatation of the mitral annulus. Geometric restoration of mitral annulus by annuloplasty has been shown to be important for the long-term durability of MV repair.5,6 Although dilatation is the most common abnormality of the mitral annulus fibrosus, the structure of the annulus itself can vary in different patients. Hutchins et al,9 in their study of 900 autopsied hearts, observed a disjunction of the mitral annulus in hearts with MV prolapse. They defined disjunction as a separation between atrial wall–MV junction and the left ventricular (LV) attachment (Figures 1 and 2). The mitral annulus is an integral part of the MV along with left atrial (LA) and LV coupling. Previous studies have demonstrated that the normal mitral annulus has a complex, nonplanar shape and function, best assessed using 3-dimensional imaging techniques.10-16 In the horizontal plane the normal annulus is elliptic in shape with a long and a short axis. The ratio between these two axes has been previously used as a measure of annular eccentricity.17 The normal annular function can be characterized by systolic annular area reduction, which may improve leaflet coaptation and normal MV closure.16,18,19 Because we have observed annular disjunction on direct inspection at operation in some patients with advanced MVD, we sought to describe the mitral annular structure and function in this particular subgroup of patients studied
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analysis of the intraoperative TEE was performed in 67 patients with advanced MVD. For comparison, intraoperative TEE from a subgroup of 32 patients with mild/ moderate MVD were analyzed. All patients provided written informed consent for the study. The study was approved by the research ethics board. TEE Examination
Figure 1 Intraoperative picture of posterior annular disjunction. Posterior mitral leaflet (PML) is detached from annulus and area of disjunction is seen between arrows.
by standardized, intraoperative, multiplane transesophageal echocardiography (TEE). Furthermore, a modified MV repair technique for this group of patients has been developed to correct this abnormality.
METHODS Study Population Between January 1995 and December 1999, 383 patients underwent MV repair by one experienced cardiac surgeon (T. E. D.). Myxomatous MVD of various degrees was the underlying MV pathology in 287 of 383 (75%) of these patients. In all patients, the degree of MVD was classified by careful intraoperative inspection and histopathologic analysis of the MV. Advanced MVD was defined by: (1) intraoperative findings of marked generalized increase in the MV thickness and volume of both leaflets, and hooding or parachute changes of the free edge of the valve with gross dilatation of the mitral annulus; and (2) diffuse histopathologic alternations of the valve tissue including expansion of the spongiosa layer, accumulation of acid mucopolysaccharides, and focal disruption of the fibrosa layer found on pathologic analysis of MV specimens. The degree of the myxomatous process was classified intraoperatively by the surgeon (T. E. D.) as mild if only the prolapsing segment was involved, or moderate if both leaflets displayed some myxomatous changes. Of 287 patients, 67 (23%) were found to have the advanced form of MVD according to the above-mentioned criteria. The remaining 220 patients were classified intraoperatively and on pathologic analysis as having moderate to mild MVD. For the purpose of this study a retrospective
Intraoperative TEE was performed in the operating room by an experienced operator using an imaging system (Sonos 2500 or 5500, Hewlett-Packard Co, Andover, Mass) with a 5-MHz multiplane transducer (OmniPlane, HewlettPackard Co). The TEE probe was placed immediately after the induction of general anesthesia, and a complete examination of the heart was performed. MV pathology was assessed using a systematic approach recently developed by our institution.20 We used a widely accepted classification scheme, originally described by Ranganathan et al21 and popularized by Carpentier et al,22 with the posterior mitral leaflet divided into 3 scallops: anterolateral, middle (P2), and posterolateral. The anterior leaflet was divided into 3 juxtaposed segments: anterior, middle (A2), and posterior.22 The number of prolapsed or flail segments was recorded prospectively for every patient. An experienced echocardiographer reviewed all TEE recordings and performed detailed offline measurements of mitral annular dimensions without knowledge of the surgeon’s classification of the degree of MV disease. The annular disjunction was present if there was a separation between the P2 insertion into the LA wall and the atrial/ventricular attachment, according to original description by Hutchins et al.9 An intraoperative photograph and a TEE image of annular disjunction in systole and diastole are shown in Figures 1 and 2, respectively. The measurement of annular disjunction was performed in a 4-chamber (0-degree rotation) midesophageal view as shown in Figure 2. The upper limit of the disjunction was defined at the level of P2 scallop insertion into the LA wall, whereas the lower limit of the disjunction was defined at the level of LA connection with ventricular myocardium (Figure 2). The distance between these two levels was measured as the annular disjunction. The change in echogenecity between the thin annular tissue and ventricular myocardium was helpful in determination of the lower level of annular disjunction. Annular disjunction was calculated as the mean of measurements from 3 consecutive cardiac cycles. For the measurements of annular diameters we used 3 midesophageal views: 4-chamber (0-degree rotation), bicommisural (75-degree rotation), and anteroposterior (135-degree rotation). To study the shape and eccentricity of the annulus in the horizontal plane we compared the diastolic annular diameters in these 3 views. Eccentricity of the annulus was calculated by the ratio between the bicommisural and anteroposterior diastolic diameters. The annular contraction was studied by comparing the diastolic and end-systolic diameters in a 0- and 75-degree
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Figure 2 Schematic diagram (A) and transesophageal echocardiographic image of mitral valve (in systole [B] and diastole [C]) with bileaflet prolapse and posterior annular disjunction. Measurements of mitral annular diameters and disjunction in systole: presumed original annulus– diameter 1 (dotted line); displaced annulus– diameter 2 (dotted line); annular disjunction– between arrows (solid line). A2, Middle segment of anterior mitral segment; LA, left atrium; LV, left ventricle; P2, middle scallop of posterior mitral leaflet. rotation views. The diastolic diameters were measured late in diastole at the P wave. To study the influence of annular disjunction on annular dimensions, the diameters of the original and displaced annulus were taken in systole in a 4-chamber (0-degree rotation) view. We measured the presumed original annulus and the displaced annulus as shown in Figure 2. Both were measured from the hinge point at the base of the A2 segment at the aortic apparatus to the upper level of the LV myocardium (original annulus) and to the point of the P2 scallop insertion into the LA wall (displaced annulus), respectively. The thickness of the mitral leaflets was measured in systole. The LV was visualized in the transgastric short-axis view and the anteroposterior, end-diastolic, and endsystolic LV dimensions were measured at the level of the papillary muscles. All measurements were obtained from 3 consecutive heart cycles and presented as a mean value. LV systolic function was also visually assessed as either normal (ejection fraction [EF] ⱖ 60%), mildly reduced (EF 40%-59%), moderately reduced (EF 20%-39%), or severely reduced (EF ⬍ 20%).20,23 The severity of MR was assessed from color Doppler information and pulmonary venous flow pattern as recently described in detail.20,24-26 MR was classified as trivial, mild, moderate, and severe,20 and the number of regurgitant jets was noted. Interobserver and intraobserver variability for annular disjunction, and annular diameter 1 and 2 in systole was assessed in randomly chosen subset of 20 of the 67 patients by two experienced echocardiographers (M. J. E. and M. J. A.). Comparison between Advanced and Mild/Moderate MVD The last 32 consecutive patients with the advanced form of MVD were compared with an age- and sex-matched group (n ⫽ 32) recruited from the remaining 220 patients with MV repair and mild/moderate MVD, undergoing
operation approximately during the same period of time. The comparison group underwent MV repair by the same surgeon (T. E. D.) between January 1995 and December 1999, and had an intraoperative multiplane TEE examination performed by the same echocardiographer, using the same standardized protocol for the evaluation of the MV pathology as did the study population.20 The TEE studies were reviewed in the same way for the patients with advanced and mild/moderate MVD, by the same echocardiographer, blinded to the surgeon’s classification of the degree of MVD. Operative Technique All patients underwent MV repair. Between 1995 and 1997 previously established and described techniques were used.4,7 In 1998 the repair technique was modified to address the issue of mitral annular disjunction. In the 31 patients operated on after January 1, 1998, most of the posterior leaflet was detached from the mitral annulus. The annulus was repaired using multiple horizontal mattress sutures, which were passed through the ventricular endocardium and displaced annulus. Next, the prolapsing segment (eg, P2) was resected, and all chordae tendineae attached to the ventricular surface of the remaining posterior leaflet were excised, leaving only the chordae attached to the free margin. The posterior leaflet was trimmed to a height of approximately 10 mm, and then reattached to the endocardium of the LV where the previous suture had been placed. Any remaining prolapsing segments of the posterior or anterior leaflet were corrected with artificial chordae of expanded polytetrafluoroethylene sutures. An annuloplasty ring or band was used in all cases to reduce the area of the mitral annulus to approximately that of the anterior leaflet. Clinical Follow-up All study patients were followed up by the referring cardiologist and annually contacted by our research personnel until October 2004. Postoperative events were
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Table 1 Clinical profile, operative data, and echocardiographic variables on 67 patients with advanced myxomatous mitral valve disease Variables
Mean age, y Male sex, n (%) NYHA functional class I/II/III/IV, n (%) LV systolic function, grade I/II/III-IV, n (%) Preoperative atrial fibrillation, n (%) Coronary artery bypass grafting, n (%) Cardiopulmonary bypass time, min Cross-clamp time, min Echocardiographic variables Annular disjunction, mm Mitral valve thickness, mm LV end-diastolic diameter, mm LA systolic diameter, mm MR grade I/II/III/IV, n Number of MR jets
52 ⫾ 14 44 (66%) 16 (23%)/25 (38%)/22 (33%)/4 (6%) 33 (49%)/29 (43%)/5 (8%) 16 (23%) 2 (3%) 97 ⫾ 31 81 ⫾ 30 10 ⫾ 3 4.1 ⫾ 0.9 60 ⫾ 8 56 ⫾ 7 0/6/27/34 2.3 ⫾ 0.9
LA, left atrial; LV, left ventricular; MR, mitral regurgitation; NYHA, New York Heart Association. Continuous variables described as mean ⫾SD.
compiled and analyzed according to the Guidelines for Reporting Morbidity and Mortality after Cardiac Valvular Operations.27 The follow-up was complete with regard to mortality and reoperations. Statistical Analysis Software (SPSS for Windows, Version 10, SPSS Inc, Chicago, Ill) was used for all statistical analyses. Continuous data are presented as mean ⫾ 1SD in text and tables. Comparisons were performed using Student paired t test or analysis of variance for continuous data, and Fisher’s exact test or the 2 test for categorical variables, where appropriate. Pearson’s correlation coefficient was used to evaluate the relationships between echocardiographic variables. Intraobserver and interobserver variability was assessed by the Bland-Altman method and by coefficient of variation (percent), calculated by dividing the SD of the difference between two measurements by the mean value of the measurements, multiplied by 100. Longitudinal data were analyzed by the Kaplan-Meier methods and survival estimates were compared using log-rank test. A P value less than .05 was considered significant.
RESULTS Table 1 shows the clinical and TEE characteristics and the preoperative and operative data of the 67 patients with advanced MVD. All patients had multisegment involvement, with 2 segments in 9 patients, 3 segments in 20 patients, and more than 3 segments in 38 patients. The midportions of both mitral leaflets, A2 and P2, were involved in 65 of 67 patients. The flail originated from the P2 scallop in 26 patients and from the A2 segment in 7 patients. Annular disjunction at the base of the P2 scallop (Figure 2) was seen in 66 of 67 patients. In one
Figure 3 Relationship between magnitude of annular disjunction and number of segments with prolapse/flail (P ⬍ .05 by analysis of variance).
patient with P2, posterior segment of anterior leaflet prolapse, and A2 flail, the annular disjunction could not be seen in the 0-degree midesophageal TEE view. The mean value of annular disjunction was 10 ⫾ 3 mm and was significantly greater for patients with a larger number of MV segments with prolapse or flail (P ⫽ .011 by analysis of variance). There was also a significant correlation between the magnitude of the disjunction and the number of diseased segments (r ⫽ 0.397, P ⫽ .001) (Figure 3). There was no significant difference between mitral annular dimensions in 3 different TEE views (Figure 4). The mean value for the eccentricity ratio between the bicommisural (43.6 ⫾ 4.6 mm) and anteroposterior (44.0 ⫾ 4.6 mm) diameter was 1.0
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coefficients of variation for the same variables were 8.1%, 3.0%, and 3.2%, respectively. Surgical and Clinical Outcome
Figure 4 Diastolic annular diameters in 3 midesophageal transesophageal echocardiographic (TEE) views (P ⬎ .05).
⫾ 0.1, suggesting that the annulus had assumed a round shape. There was no significant change in mitral annular diameters from diastole to end systole, indicating loss of annular contraction. The most recently included 32 of the 67 patients with advanced MVD were compared with 32 ageand sex-matched patients who underwent MV repair for severe MR caused by mild/moderate MVD. There was no significant difference between the two groups of patients with regard to New York Heart Assocation functional class, presence of coronary artery disease, history of endocarditis, LV function or size, or the degree of MR. The comparison of operative and echocardiographic results for the two groups are shown in Table 2. The patients with mild/moderate MVD had in total significantly fewer mitral segments involved. However, the number of flail segments was significantly higher in these patients than in the patients with advanced MVD (72% and 38%, respectively; P ⫽ .011). The annular disjunction was present only in 3 of 32 patients (9%) in the matched group and a mean value for these 3 patients was 8.2 ⫾ 4.7 mm.
Since January 1998, in addition to MV repair, correction of the annular disjunction was performed using a modified surgical technique in 31 patients. There were no operative deaths. Two of the 67 patients developed postoperative low cardiac output syndrome and were treated successfully with standard medications. There were no postoperative complications in the remaining 65 patients. Immediate postoperative TEE showed excellent hemodynamic results with no MR in 19 patients, trace MR in 41 patients, and mild MR in 7 patients. The mean pressure gradient across the repaired MV was 2.2 ⫾ 0.8 mm Hg and MV area was 2.6 ⫾ 0.5 cm2. There was no difference in the early postoperative TEE results in terms of the degree of residual MR between the patients who had operation before and after January 1998. During a follow-up of 5.9 ⫾ 1.6 years there were two noncardiac deaths for patients with advanced MVD, caused by cerebrovascular accident and cerebral atrophy. Three patients required reoperation, for recurrent MR in two and for mitral prolapse in one. In the group of patients with mild/moderate MVD there was one cardiac death caused by congestive heart failure, and one of the patients required MV reoperation. There was no significant difference in overall survival or freedom from reoperation between advanced and mild/moderate MVD groups (93.3 ⫾ 5.2% vs 85.7 ⫾ 13.2%, P ⫽ .5; and 82 ⫾ 12.9% vs 96.9 ⫾ 3.1%, P ⫽ .79, respectively). We compared survival and freedom from reoperation in the patients with advanced MVD who underwent operation before versus after the introduction of the modified MV repair in 1998. At a latest follow-up the survival was 94.7 ⫾ 5.1% in the group operated without and 96.8 ⫾ 3.2% (P ⫽ .28) in the group operated with the modified technique. There was a significant difference in follow-up between the groups (8.6 ⫾ 0.9 vs 6.1 ⫾ 0.7 years, P ⱕ .0001). The freedom from reoperation was 83.3 ⫾ 13.0% and 66.7 ⫾ 27.2%, respectively (P ⫽ .41).
Reproducibility The calculated interobserver coefficients of variation were 6.2% for annular disjunction, 2.9% for the end-systolic diameter of the original annulus, and 3.4% for the displaced annulus, both in 4-chamber view. The Bland-Altman plot shows the interobserver variability for the measurement of annular disjunction (Figure 5). No systematic bias was observed. The corresponding Pearson’s correlation coefficients were: r ⫽ 0.98 and P less than .001 for annular disjunction; r ⫽ 0.98 and P less than .001 for the original annulus; and r ⫽ 0.97 and P less than .001 for the displaced annulus. The intraobserver
DISCUSSION This study is the first, to our knowledge, to describe the echocardiographic recognition of disjunction of the posterior mitral annulus in patients with advanced MVD with bileaflet prolapse. This histopathologic abnormality was first reported by Hutchins et al9 in 1986. In their study of 900 autopsied adult hearts they noted this mitral annular abnormality in 23 of 25 hearts with floppy MVs. They described this entity as disjunction of the
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Table 2 Clinical and echocardiographic data on 32 patients with advanced and 32 patients with mild/moderate myxomatous mitral valve disease Mean age, y NYHA functional class, I and II/III and IV, n (%) LV systolic function, grade I/II-IV, n (%) Coronary artery bypass grafting, n (%) History of infective endocarditis, n (%) Cardiopulmonary bypass time, min Cross-clamp time, min LA systolic diameter, mm Mitral annulus 1*, 0-degree end systole, mm Mitral annulus 1*, 75-degree end systole, mm Mitral annulus 2, 0-degree diasatole, mm Mitral annulus 2, 75-degree diastole, mm Annular disjunction n (%) Prolapse/flail ⱖ 3 segments, n (%) Flail segments, n (%) Mitral valve thickness, mm LV end-diastolic diameter, mm LV end-systolic diameter, mm MR grade Number of MR jets
Advanced MVD
Mild/moderate MVD
P value
54 ⫾ 12 23 (72%)/9 (28%) 20 (63%)/12 (37%) 0/ (0%) 2/ (6%) 84 ⫾ 22 69 ⫾ 21 56 ⫾ 8 44 ⫾ 5 43 ⫾ 4 45 ⫾ 5 43 ⫾ 5 31/ (97%) 24/ (75%) 12/ (38%) 4.2 ⫾ 1.0 58 ⫾ 7 39 ⫾ 6 3.4 ⫾ 0.6 2.6 ⫾ 1.0
54 ⫾ 12 20 (63%)/12 (37%) 20 (63%)/12 (37%) 3/ (9%) 6/ (19%) 79 ⫾ 24 64 ⫾ 22 48 ⫾ 4 38 ⫾ 5 39 ⫾ 6 40 ⫾ 5 42 ⫾ 5 3/ (9%) 1/ (3%) 23/ (72%) 2.8 ⫾ 0.7 60 ⫾ 6 39 ⫾ 8 3.6 ⫾ 0.5 1.4 ⫾ 0.5
.28 .59 1.0 .24 .26 .43 .55 ⬍.0001 ⬍.0001 .003 ⬍.0001 .7 ⬍.0001 ⬍.0001 .011 ⬍.0001 .40 .92 .18 ⬍.0001
LA, left atrial; LV, left ventricular; MR, mitral regurgitation; MVD, myxomatous mitral valve degneration; NYHA, New York Heart Association. *Mitral annulus 1, at the level of the presumed original annulus; mitral annulus 2, displaced annulus. Continuous variables described as mean ⫾ SD.
Figure 5 Bland-Altman plot showing interobserver variability for measurement of annular disjunction in 20 patients with advanced mitral valve degeneration.
mitral annulus, ie, a separation between the atrial wall–MV junction and the LV attachment. The normal mitral annulus is typically described as a cordlike ring of circumferentially oriented collagen and elastic fibers supporting the leaflets of the MV at the atrioventricular junction.28 In contrast, for patients with disjunction the annulus seems stretched and resembles a curtainlike structure connecting the MV–LA junction and LV myocardium. The disjunction may affect the entire annulus fibrosus, or be limited only to certain segments, particularly their central and medial portions.9,29 Annular disjunction was rare in normal hearts (5.7%) in the study by Hutchins et al.9 However, Angelini et al,29 in their study of 13 autopsied hearts, encountered annular disjunction in a similar number of hearts with floppy as normal valves. Thus, the authors suggested that
this finding was simply a variant of the normal arrangement of the mitral annulus. Our results are similar to that reported by Hutchins et al.9 We observed annular disjunction in 99% of patients with advanced MVD and in only 9% of our control group. Furthermore, there was a positive correlation between the magnitude of annular disjunction and the number of diseased MV segments (prolapse or flail) in our study. Although the functional implications of annular disjunction are not entirely understood, it seems probable that there is an association between the disjunction and the severity of MV prolapse/ MVD. Hutchins et al9 hypothesized that disjunction permits hypermobility of the mitral leaflets and, therefore, may play a role in the development of prolapse and myxomatous degeneration of the MV. Recognition of annular disjunction further emphasizes the complexity of pathology of the MV apparatus, especially for patients with advanced MVD. Mitral Annular Function and Shape The functional consequences of annular disjunction may affect the shape and function of the mitral annulus. The normal mitral annulus is an essential part of the MV, and the LA and LV complex. Its physiology has been studied in experimental and clinical settings.10-16 Previous echocardiographic and magnetic resonance studies have demonstrated a complex, nonplanar, saddle-shaped or ski-slope configuration of the normal mitral annulus, which is maintained throughout the cardiac cycle.11-16 In the horizontal plane the normal mitral annulus has an
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elliptic shape, with a ratio between the two axes of 1.25 ⫾ 0.14.17 The decrease in annular eccentricity has been shown to correlate with functional MR.15 In our study there was no significant difference in any of the diameters measured in the different imaging planes with a mean eccentricity ratio of 1.0 ⫾ 0.1, suggesting remodeling of the annulus, with a complete loss of eccentricity in the horizontal plane. The annular function can be characterized by an apicobasal motion in the vertical plane, and annular area reduction in the horizontal plane. The normal annular apicobasal function facilitates LV filling in diastole and is closely linked to the LV systolic function.16,30 A 24% to 36% reduction in the mitral annular area during systole improves leaflet coaptation and normal MV closure.16,18,19 Decreased annular contraction has been shown for patients with dilated cardiomyopathy, functional MR, and MV prolapse.15,16,19,31 We did not observe any significant change in annular diameter from diastole to systole in our patients with advanced MVD. These findings suggest that not only geometry, but also function of mitral annulus, is significantly altered for patients with advanced MVD, with a loss of annular contraction. This may further impair mitral leaflet closure in these patients. TEE Assessment of MV Apparatus MV repair is currently clearly favored over prosthetic replacement for the surgical treatment of MR caused by myxomatous degeneration of the MV.3,4,7 Previous careful studies of MV anatomy21 with significant input from cardiac surgeons22 have resulted in a widely accepted classification of MV leaflets. Leaflet pathology is usually accurately assessed and well understood by echocardiographers.20,32-36 The use of intraoperative TEE in the identification and precise localization of MV lesions and mechanisms of MR has been well established.20,32-36 Indeed, recently published recommendations for standardized TEE evaluation of MV pathology have emphasized the importance of identifying abnormalities in MV leaflets and chordae tendineae.35-37 In contrast, the structural changes of the mitral annulus itself have not been the subject of systematic TEE studies. Multiplane TEE allows the entire circumference of the mitral annulus to be visualized. Therefore, our study suggests that not only annular dimensions but also annular structure should be included in the TEE assessment of the MV apparatus in all patients with myxomatous MV disease. The recognition of annular disjunction may be relevant for the choice of the optimal surgical technique used for the repair. Surgical Considerations We selected patients for our study from a large cohort of 383 patients who underwent MV repair by
Journal of the American Society of Echocardiography October 2005
one of the authors (T. E. D.) between January 1995 and December 1999. We chose patients with advanced MVD because this subgroup of patients has previously been identified as having an increased risk factor for late failure.4,7,8 The diagnosis of advanced MVD was based on the gross appearance of the MV leaflets and annulus at operation and on histopathologic examination. Our patients had voluminous, thickened leaflets and a grossly dilated mitral annulus. During operation in areas of annular disjunction, the mitral annulus was found to be posteriorly (ie, atrially) displaced. TEE examination confirmed advanced degenerative process in our study population demonstrating severe MR with multiple jets and a large number of mitral segments with prolapse or flail and dilated annulus. Annular disjunction was a common finding in this specific population both on TEE examination and on direct inspection, although no direct measurements of the disjunction were taken at the time of operation. One possible explanation for an increased failure risk for MV repair for patients with advanced MVD could be an incomplete repair as a result of an unrecognized annular disjunction. One can also speculate that disjunction may play a role in the stability of annuloplasty and durability of the repair. Therefore, we modified our operative technique to correct this abnormality. As shown by our latest follow-up data, the outcome with regard to the survival and the freedom from MV reoperation is excellent for patients who underwent MV repair for advanced MVD, and comparable with the results in the group of patients with less advanced MVD. However, we could not demonstrate any significant difference in survival or freedom from reoperation between the groups operated on before and after the modification of the surgical technique. This is probably a result of a relatively small number of patients and a very small number of events in both groups. There was a significant difference in follow-up time between the groups, which also makes the comparison difficult. Study Limitations Although all patients were prospectively enrolled to undergo an intraoperative multiplane TEE examination using a standardized protocol for the evaluation of the MV and annular pathology, the assessment and measurement of annular disjunction and annular geometry were performed by retrospective analysis of the TEE recordings. The echocardiographer performing the measurements was, however, blinded to the surgeon’s classification of the degree of MVD. The use of 2-dimensional TEE for the evaluation of a complex geometry and function of mitral annulus may be considered a limitation of this study. Recent advances with real-time 3-dimensional echocardiographic imaging provide the ability to track annular
Journal of the American Society of Echocardiography Volume 18 Number 10
dimensions in space throughout the cardiac cycle.38 However, for the purpose of the immediate recognition of the mitral annular disjunction, the standardized 2-dimensional TEE provides adequate and accurate information. Our study demonstrated that annular disjunction is common for patients with advanced MVD and is less frequent for patients with less advanced disease. This is a retrospective study in a group of patients with advanced MV pathology operated on by one surgeon; therefore, it may not be possible to generalize the results. The lack of significant difference in survival or freedom from reoperation between advanced and mild/moderate MVD indicates that even patients with advance MV disease might achieve excellent surgical result if abnormalities such as annular displacement are recognized and corrected as previously reported from our institution.4 The original publication by Hutchins et al9 indicated highest prevalence of annular displacement for patients with floppy valves; therefore, the study group has been selected based on intraoperative and histologic criteria describing MV pathology. The comparison group and study group were relatively small, nevertheless our study demonstrated that annular disjunction is common in patients with advanced MVD and is less frequent in patients with less advanced disease. However, further studies with a larger number of patients with various degrees of MVD or no mitral pathology are necessary to establish the true frequency of this annular abnormality in patients with MV prolapse and in the general population. Conclusions Our study provides new insights into the overall function and structural changes of MV apparatus for patients with advanced MVD. We demonstrated that posterior annular disjunction is a common finding and alters the geometry and function of the mitral annulus in these patients. Its recognition on TEE examination is important for the accurate evaluation of the complexity of pathologic changes in the MV and its adjacent structures, and for the choice of the optimal MV repair technique. In addition, the modification of MV repair allows surgical correction of the annular disjunction, which may further optimize long-term results in these challenging cases. REFERENCES 1. Freed LA, Levy D, Levine RA, Larson MG, Evans JC, Fuller DL, et al. Prevalence and clinical outcome of mitral-valve prolapse. N Engl J Med 1999;341:1-7. 2. Carpentier A. Cardiac valve surgery–the ⬙French correction.” J Thorac Cardiovasc Surg 1983;86:323-37. 3. Deloche A, Jebara VA, Relland JY, Chauvaud S, Fabiani JN, Perier P, et al. Valve repair with Carpentier techniques: the second decade. J Thorac Cardiovasc Surg 1990;99:990-1001.
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