Ann Thorac Surg 1997;63:1340-1345
© 1997 The Society of Thoracic Surgeons
Original Article: Cardiovascular
Midterm Results of Mitral Valve Repair With the Sculptor Annuloplasty Ring
Evelyn M. Lee, MRCP,
Leonard M. Shapiro, MD,
Francis C. Wells, FRCS
Regional Cardiac Unit, Papworth Hospital, Cambridge, United Kingdom
Accepted for publication December 2, 1996.
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Abstract
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Background. The partly flexible Sculptor ring is more physiologic than the rigid Carpentier-Edwards ring and may improve outcome.
Methods. We studied 221 consecutive patients who underwent mitral valve repair for mitral regurgitation. The Sculptor ring was randomly implanted in 30 patients (Sculptor ring group) and the Carpentier-Edwards ring in 36 patients (Carpentier-Edwards ring control group) from 1993 to 1994. Before 1993, 155 patients received the Carpentier-Edwards ring (Carpentier-Edwards ring historical group). Baseline group characteristics were similar.
Results. Thirty-day mortality in the Sculptor ring, Carpentier-Edwards ring control, and Carpentier-Edwards ring historical groups was 0.0% versus 2.8% versus 3.2% (p = 0.61), respectively. At 18 months, survival was 86% ± 6% versus 88% ± 7% versus 90% ± 3% (p = 0.89), and freedom from complications was 100% ± 0% versus 100% ± 0% versus 98% ± 1% (p = 0.51) for endocarditis, 90% ± 6% versus 94% ± 4% versus 96% ± 2% (p = 0.47) for severe mitral regurgitation, 93% ± 5% versus 91% ± 5% versus 92% ± 2% (p = 0.91) for thromboembolism, and 77% ± 8% versus 80% ± 7% versus 82% ± 3% (p = 0.49) for myocardial failure, respectively.
Conclusions. The Sculptor ring is a safe alternative to the prosthetic annuloplasty rings in current use. The benefits of its physiologic design are either clinically insignificant or undetectable with a small sample size.
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Introduction
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Outcome is better with mitral valve repair than replacement [1, 2], mainly because left ventricular function is better maintained with subvalvular preservation [3]. This has stimulated interest in maximal preservation of normal physiology. Most repairs require annuloplasty to reshape and resize a dilated annulus, improve leaflet coaptation, and prevent recurrent or progressive annular dilatation. The rigid Carpentier-Edwards ring annuloplasty (CER) has become established as a standard repair technique [4]; however, the rigid ring inhibits annular motion and theoretically may impair left ventricular function. Fully flexible alternatives, such as annuloplasty using sutures [5], pericardial tissue [6], Duran rings [7], or Cosgrove-Edwards bands [8] were therefore developed. The Sculptor annuloplasty ring (SR) is more physiologic in design. It is D-shaped with a rigid septal segment and flexible posterior segment to preserve normal annular shape, posterior annular contraction and relative immobility of the septal annulus [9]. We reviewed our midterm experience with this ring to assess its safety and potential advantages.
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Material and Methods
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Patients and Operation
We performed a retrospective review of 221 consecutive adults who underwent mitral valve repair with prosthetic ring annuloplasty by one surgeon for mitral regurgitation between 1987 and 1994. Sculptor rings (Medtronic Inc, Minneapolis, MN) were implanted in 30 patients (SR group) and the rigid CER in 36 patients (CER control group) from 1993 to June 1994. Choice of annuloplasty ring was random. Only CERs were used before 1993 (155 patients, CER historical group). Additional repair techniques were also used (Table 1
). All patients underwent preoperative coronary angiography. Coronary artery bypass grafting was performed concomitantly for all large coronary artery stenoses of 60% in diameter or more and aortic valve replacement for all hemodynamically significant aortic valve disease (Table 2). Baseline group characteristics were similar (Table 3). All patients were anticoagulated after operation. Anticoagulation was discontinued after 3 months if patients were in sinus rhythm and had no other indications. At 18 months, only 2 patients were lost to follow-up. Mean follow-up in the SR, CER control, and CER historical groups was 18.0 ± 5.0 months, 15.2 ± 6.7 months, and 39.9 ± 23.2 months, respectively.
Sculptor rings (Fig 1) were inserted after restoration of leaflet coaptation. Sutures placed through the annulus at each commissure were pulled forward to straighten the septal annulus and the anterior leaflet drawn forward and fully developed. Ring size was then chosen based on the surface area of the anterior leaflet and the intertrigonal distance using tailored sizers. Sutures were placed horizontally into the annulus and then through the suturing ring, ensuring that the markers on the ring sat at the trigones, not the commissures. The annuloplasty ring holder is grooved to protect the drawstring channel from being trapped by a stitch. Once all sutures were in place, the ring was freed from its holder and slid into place. Valve competence was assessed before and after tying of sutures by intraventricular saline injection across the mitral valve. Small commissural leaks, but not substantial leaks, may be corrected by tightening and tying the appropriate pair of drawstrings, but this was rarely required.
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Fig 1. . The Sculptor ring. (A) Ring design. (a) Suture ring. Green demarcation sutures mark the outer suture placement portion of the ring body, preventing suturing through the drawstrings. (b) The anterior segment has a semiflexible curved metal stiffener to maintain the intertrigonal distance and conform to the fibrous anterior segment of the mitral annulus. (c) The flexible posterior portion maintains physiologic shape and allows for annular contraction. Its braided structure reduces bunching of ring material with annular contraction. (d) Color-coded drawstrings allow "fine-tuning" of the circumference of the rings to optimize leaflet coaptation and minimize regurgitation. The dotted brackets indicate the four independently adjustable posterior segments. (e) Drawstrings exit on the underside of the ring to keep knots out of the blood flow path. (B) The Sculptor ring in systole and diastole. (Figures reprinted with permission from Medtronic Ltd, Watford, UK.)
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Echocardiography and Angiography
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Mitral regurgitation was graded from 0 to 4 (none to very severe) by color-flow and pulsed-wave Doppler studies. Grades 3 and 4 were hemodynamically significant. Left ventricular ejection fraction was estimated visually from left ventricular angiograms and two-dimensional echocardiograms, and by off-line analysis of echocardiograms.
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Statistical Analysis
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The Statistical Package for Social Sciences, Version 6.0, program was used for statistical analysis. Patient numbers were compared by the 
2 test. Group survival was calculated by life-table analysis and compared by the Wilcoxon (Gehan) statistic. Cox regression was used for multivariate analysis. Factors assessed were age, New York Heart Association functional class, left ventricular ejection fraction, concomitant ischemic heart disease, concomitant aortic valve disease, heart rhythm, and type of annuloplasty ring.
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Results
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Mortality
Thirty-day mortality in the SR, CER control, and CER historical groups was 0.0% versus 2.8% versus 3.2% (p = 0.61), respectively. Overall survival at 18 months after operation was 86.3% ± 6.4% versus 88.1% ± 6.7% versus 89.9% ± 2.5% (p = 0.89) and freedom from death from myocardial failure was 90.0% ± 5.5% versus 88.1% ± 6.7% versus 92.4% ± 2.2% (p = 0.86), respectively (Fig 2). Age 70 years or older (hazard ratio [HR] = 2.5, 95% confidence interval [CI] = 1.2 to 4.7, p = 0.014) and left ventricular ejection fraction of 0.40 or less (HR = 2.7, CI = 1.4 to 5.2, p = 0.004) were risk factors for all-cause death, particularly death caused by myocardial failure (HR = 3.8, CI = 1.5 to 9.7, p = 0.005 and HR = 4.4, CI = 1.9 to 10.2, p = 0.0007, respectively). Preoperative New York Heart Association functional class III or IV heart failure was also a risk factor for death caused by myocardial failure (HR = 7.7, CI = 1.0 to 58.0, p = 0.048). Rigid ring annuloplasty was not a significant prognostic indicator (CI = 0.4 to 3.5, p = 0.76 for all-cause mortality and CI = 0.3 to 3.8, p = 0.61 for death caused by myocardial failure).
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Fig 2. . Survival curves for all-cause mortality and complications of myocardial failure. (CER = Carpentier-Edwards ring; SR = Sculptor ring.)
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Myocardial failure was the main cause of death in the first 18 postoperative months. It caused all three cardiac deaths (three late deaths) in the SR group, all three cardiac deaths (one in-hospital death, two late deaths) in the CER control group, and 16 of 22 cardiac deaths (4 in-hospital deaths, 12 late deaths) in the CER historical group. The other cardiac deaths were caused by endocarditis (two late deaths), ischemic heart disease (one late death), and systemic thromboembolism (one in-hospital death, two late deaths). Malignant neoplasms caused the remaining deaths (one in the SR group and seven in the CER historical group).
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Complications
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Complication rates were similar in the SR, CER control, and CER historical groups. Complication-free survival at 18 months was 100% ± 0.0% versus 100% ± 0.0% versus 97.8% ± 1.2% (p = 0.51) for endocarditis, 89.6% ± 5.7% versus 94.0% ± 4.1% versus 95.7% ± 1.7% (p = 0.47) for severe mitral regurgitation, 93.3% ± 4.6% versus 91.0% ± 5.0% versus 92.3% ± 2.2% (p = 0.94) for systemic thromboembolism, 96.7% ± 3.3% versus 100% ± 0.0% versus 96.6% ± 1.5% (p = 0.54) for anticoagulation-related hemorrhage, and 76.7% ± 7.7% versus 79.6% ± 6.9% versus 82.1% ± 3.2% (p = 0.49) for overt myocardial failure, respectively (Fig 2
). One patient had valve-related hemolysis. None had clinically significant mitral stenosis or left ventricular outflow tract obstruction. Age greater than 70 years (HR = 2.2, CI = 1.2 to 4.0, p = 0.011), left ventricular ejection fraction of 0.40 or less (HR = 4.3, CI = 2.4 to 7.7, p < 0.0001), and preoperative New York Heart Association class III or IV symptoms (HR = 6.0, CI = 1.9 to 19.5, p = 0.0027) were risk factors for postoperative myocardial failure, but rigid ring annuloplasty was not (CI = 0.6 to 3.0, p = 0.46).
Grade 3 or 4 mitral regurgitation recurred in 11 patients. None had structural failure of the prosthetic ring. Four patients (1 in the SR group, 3 in the CER historical group) had detachment of the prosthetic ring and 4 patients (3 in the CER control group, 1 in the CER historical group) had further chord rupture, all of whom underwent successful valve replacement. Three were attributable to progressive left ventricular dilatation and deterioration in function, without ring dehiscence, leaflet prolapse or perforation, or endocarditis. Left ventricular function was too poor for reoperation. One patient (CER control group) died 1 month after operation. The other 2 patients (SR group) remain in New York Heart Association class III or IV.
The only patient in whom valve-related hemolytic anemia developed had undergone straightforward posterior leaflet quadrangular resection and Sculptor ring annuloplasty. The hemoglobin level was 9 g/dL and reoperation was inappropriate because of very poor left ventricular function. He died of heart failure 7 months after operation.
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Comment
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Influence of Type of Annuloplasty Ring on Left Ventricular Function
The importance of the intact mitral subvalvular apparatus in maintaining left ventricular function has been well established experimentally [10] and in clinical practice [3]. It is the main reason for the lower operative mortality of 0% to 6% [1, 2, 7, 8, 11–17] with mitral valve repair compared with 4% to 13% [1, 2] with replacement. However, the role of normal annular motion in the valvuloventricular interaction is not clear. Flexible annuloplasty rings reduce annular motion less than rigid rings [18], but studies in healthy animals have shown no significant benefit from preserving annular contractility. Oe and colleagues [10] found that the main benefits derive from preservation of annulus–papillary muscle continuity, while annular contraction contributes minimally. Rayhill [19] and Castro [20] and their colleagues were unable to demonstrate any reduction in left ventricular systolic function by rigid or flexible rings. Van Rijk-Zwikker and associates [18] showed that basal left ventricular filling was less impaired and unloaded stroke volume larger with flexible rings than rigid rings, but differences were small and clinically unimportant at normal arterial pressures.
Studies of normal animal hearts may not reflect clinical practice. Carpentier and co-workers [21] studied the partly flexible, physiologically designed Physio ring in 137 patients. Left ventricular performance with Physio rings and rigid rings was similar, although the use of historical controls with rigid rings compromises the accuracy of this study. Loss of flexibility with time is unlikely to be the reason for lack of observed benefit. Cosgrove and colleagues [8] demonstrated that flexibility with the Cosgrove-Edwards band persists for at least 1 year after operation and that annular contraction improves during this time. David and associates [22] randomized 25 patients to receive rigid or flexible rings. Although left ventricular function was significantly better with flexible rings at 3 months after operation, it improved further to normal in both groups by 1 year after operation with no difference in clinical outcome. The study was small and preoperative left ventricular ejection fractions were good (0.64 ± 0.12 with rigid rings, 0.63 ± 0.07 with flexible rings), resulting in good outcomes in all patients. It is conceivable that type of ring has clinical importance only in patients with significant preoperative left ventricular dysfunction, as was often the case in our patients. However, mortality and morbidity from myocardial failure were not altered by use of the Sculptor ring. Thus, the improvements in left ventricular function associated with preservation of normal annular shape and motion are either too small to have clinical significance, or the improvement in clinical outcome is undetectable with a small sample. Larger and randomized studies are required to resolve the issue.
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Influence of Type of Annuloplasty Ring on Structural Valve Failure
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There was no significant difference in complication rates of severe mitral regurgitation in the SR and CER groups. This is consistent with the findings of Cohn and colleagues [23] in 219 consecutive patients, of whom 51% had flexible rings, 20% had rigid rings, and 29% had no rings. Structural valve failure rates were lower in patients with rings than without, but were similar in patients with rigid rings and those with flexible rings.
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Other Clinical Studies of Mitral Valve Repair
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Several studies [7, 8, 11–17] have used one predominant type of annuloplasty ring, but their outcomes are not easily comparable (Table 4). Type of ring used was not associated with any consistent differences. Operative mortality was generally lower (1.0% to 2.6%) in studies with mainly rheumatic disease, perhaps because patients were younger, but the lowest rate (0%) was in a study of mainly degenerative disease [8], perhaps because most (77%) patients were well, in New York Heart Association class I or II, at operation. Late mortality increased with age from 0.4 to 0.7%/year with a mean age of less than 45 years to 4.5 to 6.0%/year with a mean age of 60 years or older. Reoperation rates were higher with rheumatic (1.6 to 5.0%/year) than degenerative (0.5 to 2.6%/year) disease, reflecting greater technical difficulty and continued active disease after operation. Most valve failures after repair occur early, resulting in higher linearized rates in studies with short follow-up.
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Table 4. . Summary of Studies of Mitral Valve Repair Using Either Rigid Rings or Flexible Rings in Patients Who Underwent Ring Annuloplasty
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Study Limitations
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Our study was limited by the small number of patients in the SR and CER control groups. However, as patient profiles and outcome in these groups were similar to the large CER historical group, it is likely that the patients in these groups were representative of the typical patient population treated at our institution.
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Conclusion
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In conclusion, patients who underwent SR and CER annuloplasty had no significant differences in outcome. No complication was directly related to the SR. Therefore, this ring appears to be a safe alternative to those in current use. Larger randomized trials comparing the different rings are needed to determine whether the theoretic advantages of the SR translate into actual clinical benefit.
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Acknowledgments
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We thank Christopher Wisbey, chief echocardiography technician, for his technical assistance.
Mr Wells was involved in the design of the Sculptor ring by Pioneering Technologies, and acts in advisory capacity for Medtronic Inc, who produce the ring. These roles involve no form of financial remuneration, and he has no financial interests in the Sculptor ring.
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Footnotes
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Presented at the 45th International Congress of the European Society for Cardiovascular Surgery, Venice, Italy, Sep 15–18, 1996.
Address reprint requests to Dr Lee, Regional Cardiac Unit, Papworth Hospital, Papworth Everard, Cambridge CB3 8RE, United Kingdom (e-mail: lmshapiro{at}fendon.win-uk.net).
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Abstract
Introduction
