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a Division of Cardiovascular Surgery, Cliniques Universitaires Saint-Luc, Université Catholique de Louvain, Brussels, Belgium
b Division of Biostatistiques, Cliniques Universitaires Saint-Luc, Université Catholique de Louvain, Brussels, Belgium
Received 20 November 2007; received in revised form 2 April 2008; accepted 9 June 2008.
* Corresponding author. Address: Department of Cardiovascular and Thoracic Surgery, Cliniques Universitaires St-Luc, Avenue Hippocrate 10, 1200 Brussels, Belgium. Fax: +32 2 7648069. (Email: Laurent.DeKerchove{at}clin.ucl.ac.be).
| Abstract |
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Key Words: Aortic insufficiency Surgery Aortic valve repair Leaflet prolapse
| 1. Introduction |
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There are multiple etiologies of LP. LP is frequent in bicuspid aortic valve (AV) disease [5] and in chronic aortic root aneurysm. The increased leaflet surface and free margin length found in connective tissues diseases (Marfan disease, bicuspid AV) and aortic root aneurysms [4] correspond to the underlying pathophysiology of chronic LP formation. The stretching of valve leaflets in the setting of aortic root aneurysm and the subsequent reduction of aortic diameter during repair procedures results in unmasked leaflet prolapse or low coaptation height than can jeopardize valve competence after AV sparing surgery [6–8] unless it is recognized and appropriately treated [3,9]. Rarely, chronic LP can be found as an isolated cause of AI in tricuspid AV [10]. Finally, acute LP can be encountered in acute type A aortic dissections [11], blunt chest trauma [12], or after rupture of a leaflet commissural fenestration [13].
In this article, we propose a clear definition for LP and describe surgical maneuvers to facilitate LP diagnosis. We also describe four different repair techniques used at our center, their indications and objective measurements for LP repair in different techniques. The aim of this study was to analyze mid-term results of AV repairs using these techniques in a large cohort of patients, to compare the different techniques used either alone or in combination, and to identify the predisposing factors for repair failure.
| 2. Material and methods |
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2.2 Surgical techniques
All patients underwent median sternotomy, with cardiopulmonary bypass and antegrade normothermic blood cardioplegia. AV exposure was obtained through a transverse aortotomy, 1 cm above the sino-tubular junction. During the study period, surgery of AV repair evolved to a more systematic approach based on the functional classification of AI [14] inspired from other classifications [15,16]. The functional classification of AI and the corresponding techniques of repair are described in Table 2
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In the normal valve, free margins usually run parallel at the same level and they join in the centre of the aortic root about 1 cm above the nadir of the sinuses of Valsalva. This level corresponds to the mid-point of the height of the commissure.
LP is defined as one of the two following situations.
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The level of coaptation is estimated by applying light tension on two adjacent commissures, and the middle of the free margin is then gently pulled down into the left ventricular outflow tract using a forceps. This point is the estimated top of the actual coaptation margin and can be compared to the commissural height.
2.2.2 LP repair
When LP is diagnosed, the choice of the repair technique is based on the leaflet pathology and tissue quality. PL and GTx techniques are indicated in case of leaflet of good quality with thin and flexible tissue; while TR and PP are indicated in case of leaflet of poor quality with severe thickening of the tissue (e.g. the raphe in bicuspid valve). The reference level used to treat LP is the normal leaflet when it exists. Otherwise, the normal anatomical coaptation level (mid-point of the height of the commissure) is taken as the reference point.
PL is performed with 6-0 polypropylene sutures in the central portion of the free margin. Plication near the commissure is avoided because of higher tension and fragility of this area (leaflet fenestration usually occurs in this area). Fig. 2 describes the technique to measure excess free margin length that needs to be plicated.
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After TR, if enough leaflet tissue is present after resection, the two edges are sutured with a running locked suture of 6-0 polypropylene and two or three interrupted sutures are added to reinforce the suture line (TR). If possible TR is not prolonged too deep through the body of the leaflet to avoid a long suture line and suturing on the delicate leaflet insertion. When the leaflet defect is too large for direct closure, an autologous pericardial patch is used. PP can also be used to repair defects that involve the free margin in the setting of rupture of large commissural fenestrations or leaflet destruction due to endocarditis. Generally, the patch size is larger than the defect area to avoid any restriction of the repaired leaflet. This results in an imprecise LP correction, which can be adjusted by the addition of GTx.
2.3 Follow-up
Follow-up data were collected by reviewing the most recent clinical and echocardiographic information obtained from medical records. Patients followed in other institutions were called personally and the most recent report (clinical and echocardiographic) from their cardiologist was obtained. The clinical follow-up was 96% complete and the echocardiographic follow-up was 94% complete. The mean clinical follow-up was 42 ± 31 months (median: 35 months, range: 9–136) and mean echocardiographic follow-up was 28 ± 25 months (median: 25 months, range: 1–124).
2.4 Statistical analysis
Continuous variables are reported as mean ± SD, and categorical variables as proportions. Survival curves were computed with the Kaplan–Meier method (Prism 2.0, GraphPad Software Inc., CA, USA); a log-rank test was used to compare curves. Pre- and intraoperative variables (Table 1) were tested in uni- and multivariate analysis for the endpoints of AV repair failure (AI grade >2 and/or AV reoperation). In bivariate analyses, the association of continuous independent variables with each outcome variable was tested with Student's t-test for independent samples. The association of binary independent variables with outcome variables was tested with Cochran–Mantel–Haenszel statistics. Cox regression modeling was then performed. Statistical as well as clinical variables were used in the model: variables significant at the p
< 0.1 were entered, and clinically meaningful variables were added. Results were considered statistically significant at the p
0.05 level. All p values were two-tailed. The SAS software (version 9.1) was used for the statistical analysis (SAS Institute Inc., Cary, NC, USA).
| 3. Results |
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Subcommissural annuloplasty was performed in 84 (57%) patients. Sino-tubular junction plication was performed in 20 (13%), shaving or decalcification in 18 (12%), supra commissural aortic replacement in 18 (12%), and AV sparing surgery in 61 (42%) with 51 (35%) reimplantation and 10 (7%) remodeling techniques.
3.2 Postoperative results
There was no hospital mortality. During initial hospitalization, two patients required reoperation for recurrent AI. Of these, one had suture dehiscence and was re-repaired. A third patient was reoperated for aorto-right ventricular fistula and was re-repaired. At discharge, the mean AI grade was 0.8 ± 0.7, with 52 (36%) patients having no AI, 78 (54%) having grade 1, and 15 grade 2 (10%). During follow-up, two patients died, one from ischemic heart failure (no AI recurrence) and the other from trauma. Three patients required late reoperation for recurrent AI (at 30, 33 and 35 months); of them, one presented with dehiscence of a pericardial patch suture and another developed AV stenosis due to calcification. No other AV stenosis was recorded at follow-up. Echocardiographic follow-up, available in 130 patients (8 patients lost or without TTE follow-up, 2 deaths and 6 AV reoperation), showed a mean AI grade of 1.0 ± 0.7, with 101 (78%) patients having no or grade 1 AI, 22 (17%) having grade 2, and 5 (4%) having grade 3. One episode of AV endocarditis (medically treated) and three strokes were recorded during follow-up period.
Overall survival at 4 and 8 years was 99 ± 1% and 96 ± 4% respectively. Overall freedom from reoperation and from recurrent AI (grade >2) at 4 years were 94 ± 5% and 91 ± 7% respectively. (Fig. 3 ) Comparing patients having one versus more than one LP repair, freedom from recurrent AI was not significantly different (88 ± 11% vs 92 ± 8%, p = 0.2).
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| 4. Discussion |
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Aortic valve repair has several proposed advantages over prosthetic valve replacement. First, it preserves the dynamic native aortic valve annulus and native valve tissue, which may have hemodynamic benefits over a rigid prosthetic valve stent. Secondly, avoidance of a mechanical prosthesis, which would often be used in this young population, reduces the risk of thromboembolic and anticoagulation-related complications. Lastly, valve repair has been proposed to have a low incidence of valve endocarditis.
In this study, we analyzed immediate and mid-term results of LP repair in a large cohort of patients operated electively for AI and/or aortic aneurysm. We have shown that with a systematic analysis of the AV, LP can be effectively repaired. The quality of the leaflet tissue is of major importance and resection with direct closure or with patch leads to leaflet fragility that must be correctly reinforced. Multiple leaflet prolapse is not a prohibitive factor for successful repair even in the absence of a clear reference level such as a normal leaflet, as long as normal anatomical coaptation is achieved.
In reconstructive surgery for AI, the functional classification is a useful tool for the surgeon. It is a comprehensive classification of the different mechanisms of AI that allows the surgeon to categorize pathological findings into different abnormal functional entities and apply the corresponding repair techniques. In those procedures, annuloplasty and leaflet repair are always considered together to achieve optimal coaptation and stability over time. In this study, overall freedom from AV reoperation is slightly better that the one reported in two meta-analyses [19,20] and freedom from AI grade >2 is equivalent to the one reported in comparable series of AV repair [21]. In our experience, 50% of patients having AV sparing surgery required LP repair and the results of this group are equivalent to the group without prolapse repair [3]. Similar results of leaflet repair in AV sparing surgery have also been reported by others [22]; whereas, no or inadequate leaflet repair in those patients has shown a detrimental impact on AI recurrence [7,8].
We show comparable results for PL and GTx techniques and for the combination of both. Therefore, it is unlikely that there are any deleterious effects of the addition of GTx on the PL and we can hypothesize a potential benefit of additional GTx in cases of more severe LP. As an alternative, Schäfers et al. have described a technique in which successive addition of plication stitches is used to achieve the adequate correction of LP [4].
The GTx technique, first described in by David et al. [23], was used since the beginning of the study period. Until last follow-up, we did not observe, either on echocardiographic report or at surgical inspection in late reoperations (n = 3), any restrictive motion due to free margin fibrosis or calcification. This observation confirms the excellent biocompatibility of PTFE materials already reported for many years for vascular prostheses, and more recently for artificial mitral valve chordae.
In TR or PP repair, the risk of suture dehiscence is well known and incriminated as the main factor contributing to repair failure [19,24]. In our experience, particular attention to the suture line technique (using a locked running suture + interrupted stitches) has allowed us to minimize the rate of dehiscence (3.3%, 2/61 patients) and the addition of GTx to TR and PP has allowed us to abolish them (0/48 patients).
4.1 Study limitations
Besides the inherent limitations related to the retrospective design of this study, the disparities in the echocardiographic follow-up somewhat limit the amount of data suitable for statistical analysis. Variables such as quantitation of residual AI, orientation of the regurgitant jet and the recurrence of LP were missing in many reports. For this reason, we considered any recurrent AI >2 as failure of AV repair and consequently failure of LP repair. The study population may also be considered as heterogeneous (tricuspid valve, bicuspid valve, with or without aortic aneurysm), but in this study, we included a large number of patients to analyze the results of the different techniques and their association. Further analyses are necessary to evaluate the long-term durability of these techniques of aortic prolapse repair and to compare them to AV replacement.
| 5. Conclusion |
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| Appendix A |
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Dr H. Schafers (Homburg, Germany): Let me make two comments. Only about half of your patients were treated for cusp prolapse in the presence of preoperative aortic regurgitation grade II or less. Can you comment on why these valves were repaired?
The second question, I would like to challenge your definition on complete or absolute cusp prolapse. Normally the free margins at their lowest points are about 8 to 10 mm above the level of the aorto-ventricular junction. However, you said absolute prolapse is only present when the free margins are below the level of aorto-ventricular junction, so that's a difference of 8 to 10 mm.
Dr de Kerchove: To answer to your first question, 25% of the patients had preoperative aortic regurgitation grade I or II and 75% had more. Those 25% were operated for proximal aorta dilatation as primary surgical indication and they received valve sparing operation or ascending aorta replacement. In this group prolapse is usually an intraoperative finding where leaflets present differences in their free margins levels. A typical example is in sparing surgery where the reduction of the root caliber can produce a prolapse of a distended leaflet. We believe that in those cases, optimizing and equalizing of the leaflet free margins levels is preferable for the immediate and the long-term aortic valve competence.
Dr Schafers: Absolute cusp prolapse is the other term. You showed a nice picture where the height difference was 8 to 10 mm approximately, but still in your definition you said below aortic valve plane, whatever that means. I assume aorto-ventricular junction.
Dr G. El Khoury (Brussels, Belgium): We call relative prolapse when the leaflets free margins are at different levels but still above the aorto-ventricular junction. When the free margin is really below the aorto-ventricular junction we speak about absolute prolapse. Distinction between relative and absolute prolapse can be made on echocardiographic long axis view and by surgical inspection.
Dr B. Koul (Lund, Sweden): You showed us the data when you have repaired the cusp prolapse by doing a subcommissural plication or a Gore-Tex suture of the free leaflet margin or by a combination of both. But, however, there was no clear data as to when you choose subcommissural plication or a Gore-Tex suture of the leaflet margin.
You showed us data of about 54 patients, and how did you decide when you need to combine both techniques or add one or the other cusp repair technique to the third procedure of aortic annuloplasty?
Dr de Kerchove: When we have an isolated cusp prolapse, and I mean by isolated a prolapse not associated to a root dilatation, we systematically add two or three subcommissural plication stitches. When prolapse is associated to root dilatation, we perform valve sparing operation, principally the reimplantation procedure, in which subcommissural plications is not necessary because of the annuloplasty by the Dacron graft. Concerning your second question, the Gore-Tex suture is preferred in very fragile fenestrated free margin, while plication is done in case of excellent quality of the tissues. Addition of Gore-Tex to another technique of prolapse repair is done to reinforce the free margin and/or to accentuate the correction of the prolapse.
Dr M. Antunes (Coimbra, Portugal): I think well have to move on. We are well beyond time.
| Acknowledgments |
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| Footnotes |
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Presented at the 21st Annual Meeting of the European Association for Cardio-thoracic Surgery, Geneva, Switzerland, September 16–19, 2007. | References |
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