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a Division of Cardiovascular Surgery, University Hospital of Geneva, Geneva, Switzerland
b Unit of Pediatric Cardiology, Department of Pediatrics, University Hospital of Geneva, Geneva, Switzerland
Accepted for publication March 3, 2008.
* Address correspondence to Dr Kalangos, Division of Cardiovascular Surgery, University Hospital of Geneva, 24 rue Micheli-du-Crest, Geneva 14, CH-1211, Switzerland (Email: afksendyios.kalangos{at}hcuge.ch).
Presented at the Forty-fourth Annual Meeting of The Society of Thoracic Surgeons, Fort Lauderdale, FL, Jan 28–30, 2008.
| Dr Kalangos discloses that he has a financial relationship with Bioring SA.
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Abstract |
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 Top Abstract IntroductionPatients and MethodsResultsCommentDiscussionReferences |
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Methods: Between January 1994 and March 2006, 220 children underwent mitral valve repair for rheumatic valve disease. Mitral valve insufficiency was predominant in 198 patients (90%). Fifty-seven patients (26%) had associated aortic valve insufficiency and 51 (23%) had tricuspid valve insufficiency addressed during the same surgery. A mitral valve ring was used in 213 patients (173 Carpentier-Edwards and 40 biodegradable rings). Ninety-two percent (202 of 220) were in New York Association class III to IV. Echocardiography was performed at 6 months and thereafter once yearly.
Results: There were no hospital deaths or major postoperative morbidity. Follow-up was complete in 96% (212 of 220). One late death occurred. Mean follow-up was 76.4 months (range, 1 to 13 years). One patient (0.5%) had immediate mitral valve repair failure and required mitral valve replacement. Twelve patients (5.5%) required reoperation during follow-up. Recurrent mitral valve insufficiency/stenosis-free survival was 94.5% at 5 years and 92.7% at 10 years. Mean gradient was 5.2 ± 1.9, 6.2 ± 2.0, and 7.0 ± 2.3 mm Hg, respectively, at 7 days, 6 months, and 1 year postoperatively for the Carpentier-Edwards ring and significantly lower (p < 0.001) for the biodegradable ring at 2.8 ± 0.5, 3.1 ± 0.7, and 3.3 ± 0.5 mm Hg, respectively. Unchanged mean gradient during the first year was 65% (26 of 40) for the biodegradable ring and 21% (31 of 147) for the Carpentier-Edwards ring.
Conclusions: Mitral valve repair in children with rheumatic valve disease has excellent immediate results with low operative risk and satisfactory midterm results and should therefore be the preferred treatment of choice. The use of biodegradable mitral valve ring results in a significant lower mean gradient during the first year of implantation compared with the Carpentier-Edwards ring and is available in a wide range of sizes.
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Rheumatic fever and rheumatic heart disease has been decreasing in incidence in most developed countries, but worldwide remains a very significant cause of cardiovascular morbidity and mortality. In 1994, it was estimated that 12 million persons suffered from rheumatic fever and rheumatic heart disease worldwide [1]. A large proportion requires valve surgery within 5 to 10 years and many are children [2]. Mitral valve repair techniques initially described by Carpentier have showed promising results [3]. Mitral valve repair, if technically feasible, remains the procedure of choice for the pediatric rheumatic population although its midterm and long-term performance is less stable than in degenerative lesions [4–6].
We have reviewed our 13-year single-surgeon (A.K.) experience with repair of rheumatic mitral valves in children to determine late outcome as well as the differences in echocardiographic parameters related to the use of a biodegradable annuloplasty ring introduced into clinical practice in 2003 compared with the traditional Carpentier-Edwards rigid annuloplasty ring.
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Patients and Methods |
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TopAbstractIntroductionPatients and MethodsResultsCommentDiscussionReferences |
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Demographics
From January 1994 to March 2006, 220 children underwent mitral valve repair for rheumatic valvar disease using many of the techniques described by Carpentier [3, 7]. Mean age was 11.8 ± 3.0 years (range, 5 to 16). Children in whom a biodegradable annuloplasty ring was used were significantly younger than those receiving the Carpentier-Edwards annuloplasty ring (10.2 ± 3.8 years [range, 5 to 16] versus 11.8 ± 3.1 years [range, 6 to 16], p < 0.001). Between 1994 and April 2003, a Carpentier-Edwards ring was implanted in all patients. Between May 2003 and the end of 2004, the biodegradable ring was implanted in cases for the clinical study (approved by the Ethics Committees) in the aim for CE (Conformity Marking Europe) mark approval. Since the approval of the CE mark in May 2005, the ring has been routinely used in all cases without any restriction in terms of pathology.
There were 142 girls (65%) and 78 boys, with a mean weight of 26.3 ± 9.9 kg (range, 8 to 52 kg). Eighty-two percent of the patients were underweight or thin for their age at the time of operation. Before surgery 92% (202 of 220) of the patients were in New York Heart Association (NYHA) class III or IV. All of the patients were from African and Asian countries and had a well-documented history of rheumatic fever determined by the revised Jones' criteria [8]. Twenty-six percent (57 of 220) of the patients had associated aortic valve insufficiency grade III or IV, and 93% (53 of 57) of them underwent simultaneous aortic valve repair, and 4 had aortic valve replacement with a mechanical prosthesis. Fifty-one patients (23%) had concomitant tricuspid insufficiency grade III or IV, and all of them underwent concomitant tricuspid valve annuloplasty. Thirty-eight of them (75%, 38 of 51) had a DeVega annuloplasty for correction of a functional tricuspid insufficiency, and 25% had ring annuloplasty for correction of organic tricuspid insufficiency. Thirty-two received a Carpentier-Edwards ring (Edwards Lifesciences, Irvine, CA), and 6 received a Kalangos biodegradable ring (Bioring SA, Lonay, Switzerland).
Sixty-two of 220 children (28%) had atrial fibrillation before surgery. Six patients (3%, 6 of 220) had triple-valve disease. Predominant mitral regurgitation was present in 90% of the patients (198 of 220). There was pure mitral regurgitation in 60% (132 of 220) and 30% mixed valve lesions (66 of 220), and in only 10% of the patients (22 of 220) was a pure mitral valve stenosis present. Nine patients had active rheumatic carditis at the time of surgery based on clinical examination, serologic criteria, and surgical macroscopic evaluation. Two patients had history of treated bacterial endocarditis. Pure mitral insufficiency was present in 77% (31 of 40) and mixed valve lesions in 23% (9 of 40) of the children in whom a biodegradable ring was used. Thirty-five of these 40 patients were in NYHA class III or IV. Two of them had active rheumatic carditis at the time of surgery, and 5 had atrial fibrillation before surgery. Six patients had concomitant functional tricuspid insufficiency grade IIII and underwent concomitant annuloplasty with a biodegradable tricuspid ring. Nine patients had concomitant aortic insufficiency grade III or IV and underwent concomitant aortic valve surgery.
Operative Techniques
Cardiopulmonary bypass was established by ascending aortic and bicaval cannulation. Between January 1994 and December 1999, myocardial protection consisted of systemic hypothermia to 28°C, topical hypothermia, and antegrade hyperkalemic crystalloid cardioplegia. Since 2000, all patients were operated upon at normothermia and myocardial protection using cold antegrade hyperkalemic crystalloid cardioplegia repeated every 20 minutes. The mitral valve was explored through a left atriotomy performed in the interatrial groove. Each structure of the mitral valve was analyzed systematically. The surgical procedures included comissurotomy (n = 88), chordal shortening (n = 66), cusp thinning (n = 30), chordal transfer (n = 47), secondary or primary posterior chordal resection (n = 83), and posterior leaflet suspension (n = 21) [9]. Secondary chordal transfer to the primary position was mainly used either in cases of anterior leaflet prolapse due to chordal rupture or in cases of anterior leaflet pseudoprolapse due to restricted posterior leaflet motion.
Annuloplasty rings were used in 97% of the patients (213 of 220). In 81% (173 of 213) of the patients, a rigid Carpentier-Edwards ring was used, and in 19% (40 of 213) a biodegradable Kalangos ring was used. An annuloplasty ring was implanted in 15 of 22 patients with pure mitral stenosis to correct the annular deformity and minimize the commissural leaks after commissurotomy. Seventeen percent of the patients with pure mitral regurgitation without any transmitral gradient on preoperative transthoracic and esophageal echocardiography required a small commissurotomy owing to the presence of partial commissural fusion noticed during the analysis of the mitral valve. We prefer to perform partial commissurotomy in such cases to avoid progression of commissural fusion after surgery. The implantation technique of the biodegradable ring was previously described [10]. The mean prosthetic Carpentier-Edwards ring size used was 30 ± 3, ranging from 26 to 34. The mean size of the biodegradable ring was 26 ± 6, ranging from 22 to 32 (p < 0.001). Carpentier-Edwards and biodegradable ring sizers have similar surface areas for adult sizes between 26 and 36, but pediatric sizes below 26 do not exist for Carpentier-Edwards rings. The distance between the two corners of the superior border of the sizer for biodegradable rings, should in principle, correspond to the physiological intertrigonal distance when the applied sizer covers the entire surface of the anterior mitral leaflet.
The various mitral valve structures on which these techniques were applied according to the type of mitral valve dysfunction are shown in Table 1.
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Follow-Up
Transthoracic echocardiography was carried out in all patients before surgery, before discharge from the hospital, and at 3 and 6 months postoperatively in the outpatient clinic of our institution before returning to their countries of origin. Doppler echocardiographic grade of mitral regurgitation was measured with color Doppler flow and graded according to the width and length of the regurgitant jet in the left atrium (grade I to IV). The mean gradient across the mitral valve was estimated by measuring the peak diastolic velocity from Doppler studies in a four-chamber view. Left ventricular end-diastolic (LVEDD) and end-systolic diameters (LVESD) as well as left ventricular shortening fraction were measured at midpapillary level in the standardized parasternal transthoracic long-axis or short-axis position. Two-hundred-twelve of the 220 patients (96%) were thereafter followed in outpatient clinics by cardiologists in their countries of origin, who periodically informed us of the patients' evolution by filling out a questionnaire including clinical, echocardiographic, and medication information. Follow-up in this study was achieved until May 2007. We followed standard published guidelines in reporting freedom from valve-related events [11].
Statistical Analysis
Data are presented as mean ± SD. Continuous variables were analyzed with the Student t test and categorical variables using the 
2 test. Actuarial estimates were calculated using the Kaplan-Meier method.
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Results |
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TopAbstractIntroductionPatients and MethodsResultsCommentDiscussionReferences |
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One patient with a Carpentier-Edwards ring implantation underwent early reoperation (within 30 days) owing to failure of the repair, which required a mitral valve replacement, thus bringing the incidence of early reoperation rate as low as 0.5% (1 of 220). This patient had serologically positive acute pancarditis.
Late Outcomes
Follow-up was complete in 96% of the patients (212 of 220). The 8 cases lost to follow-up were cases from the early part of the series. Mean and median follow-up was 76.4 ± 38.6 months and 74 months, respectively, ranging from 1 to 13 years for all the cases. The median follow-up for the Carpentier-Edwards group was 78 months and 29 months for the biodegradable ring group. One patient died in the ninth postoperative month of septicemia and multiple organ failure in a remote hospital, with apparently competent aortic and mitral valves. The initial mitral valve lesion was stenotic. In 1 patient with a Carpentier-Edwards ring implantation, infective endocarditis with Staphylococcus aureus developed and the patient was treated conservatively in his home country. This patient subsequently underwent mitral valve replacement 19 months after the initial repair. No thromboembolic events or hemolysis were detected during the follow-up period.
A total of 12 patients, all with Carpentier-Edwards ring implantation, underwent reoperation (beyond 30 days) for severe valve dysfunction after a mean period of 38 ± 42 months (range, 2 to 132) from the initial mitral valve repair. Three of them had a repeat mitral valve repair within 6 months of the initial repair, 2 owing to dehiscence of the annuloplasty ring (Carpentier-Edwards ring) and 1 because of technical failure of the repair including a chordal shortening plasty. Eight of the remaining 9 patients who had reoperation underwent mitral valve replacement after a mean period of 44 ± 42 months (range, 6 to 132), and 1 patient had a repeat mitral valve repair 8 years after the initial repair. Five of the 8 patients who underwent mitral valve replacement demonstrated clinical and serologic evidence of recurrence of their rheumatic heart disease during the follow-up period. At reoperation, fusion of the leaflets and chordae at both commissural sites together with severe tissue retraction were noted in all 8 patients. Two of the 9 patients who had serologic and macroscopic evidence of acute carditis at the time of surgery needed reoperation, the first one within the first postoperative month and the other within 6 postoperative months.
Valve Function
Of the 212 patients followed up, 178 (84%) had no or trivial mitral valve regurgitation and 15 (7%) showed mild mitral regurgitation at their last follow-up echocardiography. Nineteen patients (9%) had significant mitral regurgitation during the follow-up after a mean period of 40 ± 36 months after the initial repair. The mitral regurgitation was moderate to severe (grade III) in 10 patients (53%) and severe (grade IV) in 9 (47%) The 9 patients with severe mitral regurgitation and 3 patients with grade III mitral regurgitation all underwent reoperation, and interestingly, all of them had mixed mitral valve lesions at the initial surgery. The remaining 7 patients with moderate to severe (grade III) mitral regurgitation are scheduled for reoperation.
Freedom from mitral valve reoperation due to significant mitral regurgitation was 94.5% (confidence level [CL] 70%: 94% to 98%) at 5 years and 92.7% (CL 70%: 90% to 96%) at 10 years after the initial operation. Mitral valve–related event-free survival (including early and late deaths, reoperation, moderate to severe mitral regurgitation, and endocarditis) was 93.2% at 5 years (CL 70%: 90% to 96%) and 86.5% (CL 70%: 86% to 93%) at 10 years after the initial operation (Fig 1). No thromboembolic events occurred.
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Corresponding values for the biodegradable annuloplasty group (n = 40) were 6.0 ± 0.9 cm (range, 4.7 to 8.0 cm) and 3.4 ± 0.9 cm (range, 2.2 to 6.0 cm) preoperatively; and 4.7 ± 0.6 cm (range, 3.8 to 6.8 cm) and 2.9 ± 0.6 cm (range, 2.0 to 4.7 cm) at hospital discharge, a significant decrease. At 3 months postoperatively, LVEDD and LVESD continued to decrease, 4.0 ± 0.4 cm (range, 3.0 to 5.0 cm) and 2.8 ± 0.6 cm (range, 2.0 to 4.2 cm; Fig 3).
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Comment |
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TopAbstractIntroductionPatients and MethodsResultsCommentDiscussionReferences |
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Freedom from reoperation after mitral valve repair in a rheumatic population increases with age, the reasons for reoperation being suboptimal initial repair, errors in judgment with attempts to repair an irreparable valve, especially in mixed complex lesions, technical failures, and recurrence or progression of rheumatic disease with time. Our experience with mitral valve repair has been encouraging, the freedom from reoperation being 93.2% at 10 years, a striking difference when compared with that of other series reported in the literature [5, 6, 13, 15–17]. This difference is partially attributable to the use of meticulous repair techniques aimed at achieving optimal reconstruction of the rheumatic mitral valve and avoiding errors in judgment in choosing between repair and replacement on initial operation. As mentioned by Carpentier in the discussion section of Yau's article [5], the main factors predicting reoperation in his rheumatic series were annulus dilatation (16%) without the use of a ring on the initial operation, predominantly stenotic lesions (16%), leaflet retraction (32%), and leaflet prolapse (32%).
Our biodegradable ring allowed us, to perform annuloplasty in 15% of the children in our series (6 of 40) with rheumatic disease with ring sizes under 26, sizes not available with traditional rings, hence extending the possibilities of valve repair in younger children, without the need for leaflet extension using glutaraldehyde-treated autologous pericardium. Fibrosis of this autologous pericardium, sometimes already affected by pancarditis before surgery, seems to be unavoidable over time based on our experience in correcting rheumatic aortic insufficiency with the aortic cusp extension technique using short-time glutaraldehyde-treated autologous pericardium. This point brings into discussion the fact that the structural deterioration of pericardial extension patches could probably increase the reoperation rate, the freedom from reoperation in this subset of patients being 70% at 10 years [16]. Because of the ease of implantation of the biodegradable ring, our aortic cross-clamp and cardiopulmonary bypass times are reduced by 10 minutes compared with those of our Carpentier-Edwards ring implantations. Moreover, we have had no thromboembolic complications over the postoperative follow-up period in the absence of anticoagulation therapy.
Another important observation is that with the biodegradable ring, there is a smaller decrease in postoperative shortening fraction at 1 week compared with that of Carpentier-Edwards ring group. We can speculate that the three-dimensionally flexible nature of the biodegradable ring (which is a partial ring by design) better preserves the contractility of the native annulus, as reported with other flexible rings [18]. The biodegradable ring allows for better preservation of annular contractility and reduced aortic cross-clamp times, which is especially important in children with end-stage valve-related heart failure or with low left ventricular ejection fractions.
In our series, patients with a biodegradable ring inserted in the native annulus had lower transmitral gradients during the first postoperative year in both the pure mitral insufficiency and the mixed lesions groups (more prone to developing stenotic recurrent lesions at midterm and long term) as compared with those of the Carpentier-Edwards annuloplasty ring group. The increase in transvalvular gradient is usually due to recurrence or progression of the rheumatic process itself and can also be attributed to the extension of dense fibrous tissue covering the annuloplasty ring onto both leaflets of the mitral valve, thereby narrowing the orifice and rendering the leaflets, already affected by the rheumatic process, even stiffer, thicker, and less mobile [19, 20]. During the first postoperative year, the fact that no patient had recurrent rheumatic fever in either the Carpentier-Edwards group or the biodegradable group does not explain the statistically significant difference in transvalvular gradients by the faster progression of the rheumatic process in the Carpentier-Edwards group and not in the biodegradable ring group. In contrast with rigid rings, on repeat postoperative echocardiographic controls, preoperative mobility of the posterior leaflet in the biodegradable ring group is preserved after surgery, probably because the fibrous tissue induced by ring degradation does not spread over the insertion line of the posterior leaflet onto the native annulus.
Technical failures are usually the reason for early reoperation. Two patients required early repeat mitral valve repair owing to dehiscence of the Carpentier-Edwards ring, a risk nonexistent with the biodegradable ring, which is inserted into, rather than onto, the native annulus.
Leaflet prolapse requiring reoperation can be related to early or late valve failure. We had 2 such patients who required mitral valve replacement, the one within the first 30 days of surgery, and the other after 30 days. In the first case, significant residual mitral insufficiency was due to abrasion of the split papillary muscle by the suture material, serving to bury the extra length of the elongated chordae tendineae in the longitudinal trench. In the second case, chordal rupture, far away from the suture material, was probably the cause, and was due to the increased tension applied on the shortened inflammatory primary chordae tendineae. In these 2 patients, there was serologic evidence of persistent inflammation before repeat surgery, despite anti-inflammatory steroidal therapy started 3 months before initial surgery.
Progression of leaflet retraction after initial repair is the most important cause of reoperation in the rheumatic pediatric population. Five of the 9 patients who underwent mitral valve replacement after the fifth postoperative year in our series had clinical and serologic evidence of recurrent rheumatic fever, with recurrent episodes, already after the second postoperative year when antibiotic prophylaxis was neglected.
In conclusion, mitral valve repair should be the preferred strategy in children with rheumatic heart disease whenever feasible. Use of a biodegradable ring, available in pediatric sizes, also seems to contribute to early and midterm improvement of some valve-related factors, increasing the durability of mitral valve repair in children with rheumatic disease.
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Discussion |
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TopAbstractIntroductionPatients and MethodsResultsCommentDiscussionReferences |
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DR CHRISTENSON: We managed to perform primary mitral valve repair in 90% to 95% of children with rheumatic mitral valve disease.
DR CHARLES D. FRASER (Houston, TX): I might just comment again, from the manuscript, I note that 100% of the patients were from Asia or Africa. Is that correct?
DR CHRISTENSON: Almost 100%. A large proportion of the patients were operated on in our humanitarian program on pediatric cardiac surgery, where we have regular contact with the local cardiologists. Therefore, the follow-up of these patients could be securely achieved through continuous reporting from the cardiologists.
DR FRASER: Well, the point being that worldwide rheumatic valvular disease in children is still a very significant problem even though we don't see it much in the United States, but around the world it's a very significant problem.
DR GERHARD ZIEMER (Tuebingen, Germany): Whenever we use anything absorbable in pediatric cardiac surgery, we say we use it because we expect growth and then we're very happy about it. What I did not recognize in your presentation, however, is the fact that you really could show or give data on actual growth in patients and their mitral annuli.
In all of your teenage patients, the diameters of rings implanted were smaller than for the normal adult, but they are still pretty big. So let's say there was a 26-mm ring in an 11-year-old. If you would look at this kid 8 or 9 years later, did or would you see the same good valve function you managed to receive early postoperatively, 8 years later, with an annulus that grew, that was of normal size for age and height and weight? Or would/did you see good/poor valve function with a 26-mm annulus that did not grow?
DR CHRISTENSON: We haven't addressed that issue because, as you saw from my presentation, we started to use the biodegradable ring first in 2003, which means that we have a maximum of 5-year follow-up period. However, we have had no reoperations so far in the group where the biodegradable annuloplasty ring was used.
DR ZIEMER: So how do you know that it was really absorbed in these patients and allows for growth?
DR CHRISTENSON: All the data, when it comes to resorption of the ring itself, we have from animal studies, which have shown quite clear histologic evidence that within 6 months these rings dissolve. For further information, see the article in the Journal of Heart Valve Disease.
DR ZIEMER: It looks to me that for our small patients, there is still some or even a lot hope involved.
DR RALPH S. MOSCA (New York, NY): I have a question, sort of a corollary to Dr Ziemer's question. I have not used a biodegradable ring so I can not comment on their utility. Often, however, when rings are presented for use in atrioventricular valve repairs, there is concern over the effect on growth of the AV valve annulus. Surgeons routinely comment that growth of the annulus is necessary and that we should do all that we can to promote it. Absorbable rings have thus been touted as preferable to nonabsorbable rings; the latter by inference are supposedly responsible for lack of growth. Have you seen any patients where you placed nonabsorbable rings, or for that matter mechanical valves, where the AV valve annulus did not grow?
I have not had that experience. They may not grow as well as a normal child's annulus, but this annulus typically started off smaller. For example, if you replace the mitral valve in a 2-year-old and you need to replace it again in the same patient at 10 years of age, an appropriate size valve will fit. So the annuli seem to grow despite the presence of the prosthetic ring.
DR CHRISTENSON: I think that is a very good question. I don't have sufficient data on this issue that I can present today. However, the advantage, the major advantage, with the biodegradable ring, in my view, is that there is no tissue overgrowth when the biodegradable ring is used, which is one of the major reasons for reoperation when rigid or semirigid rings annuloplasty rings are used. This means that the reoperation rate for failure when biodegradable annuloplasty rings are used is more or less eliminated because there is no foreign material whatsoever outside the annular tissue itself.
DR MOSCA: I would agree. That's a different argument, but certainly a good one to make for its use if the valve function remains acceptable.
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References |
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TopAbstractIntroductionPatients and MethodsResultsCommentDiscussionReferences |
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This article has been cited by other articles:
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  J. T Christenson and A. Kalangos Use of a Biodegradable Annuloplasty Ring for Mitral Valve Repair in Children Asian Cardiovasc Thorac Ann, January 1, 2009; 17(1): 11 - 12. [Full Text] [PDF]
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M. Cikirikcioglu, E. Pektok, P. O Myers, J. T Christenson, and A. Kalangos PEDIATRIC MITRAL VALVE REPAIR WITH THE NOVEL ANNULOPLASTY RING: KALANGOS-BIORING(R) Asian Cardiovasc Thorac Ann, December 1, 2008; 16(6): 515 - 516. [Full Text] [PDF]
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