Ann Thorac Surg 2004;78:1403-1408
© 2004 The Society of Thoracic Surgeons
Original article: cardiovascular
Current Status of Surgery for Rheumatic Carditis in Children
Neal D. Hillman, MDa,*,
Lloyd Y. Tani, MDb,
L. George Veasy, MDb,
Linda L. Lambert, MSNa,
Gregory B. Di Russo, MDa,
Donald B. Doty, MDc,
Edwin C. McGough, MDa,
John A. Hawkins, MDa
a Division of Cardiothoracic Surgery, Primary Children's Medical Center and the University of Utah, Salt Lake City, Utah, USA
b Division of Cardiology, Primary Children's Medical Center and the University of Utah, USA
c Department of Cardiovascular Surgery, LDS Hospital, Salt Lake City, Utah, USA
Accepted for publication April 27, 2004.
* Address reprint requests to Dr Hillman, Cardiothoracic Surgery, Primary Children's Medical Center, Suite 3800, 100 N Medical Dr, Salt Lake City, UT 84113, USA
neal.hillman{at}hsc.utah.edu
Presented at the Poster Session of the Fortieth Annual Meeting of The Society of Thoracic Surgeons, San Antonio, TX, Jan 26–28, 2004.
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Abstract
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BACKGROUND: The incidence of rheumatic heart disease (RHD) has increased recently in the western United States. We reviewed our 18-year surgical experience with RHD in children to examine current surgical techniques and results.
METHODS: From 1985 until 2003, 596 children (<21 years) with rheumatic fever were seen at Primary Children's Medical Center. Rheumatic carditis was diagnosed in 366 patients (61.4%). Twenty-six with carditis (26/366, 7.1%) required operation for rheumatic valve disease including 8 for mitral regurgitation, 7 for mitral and aortic regurgitation, 4 for aortic regurgitation, 4 for mitral regurgitation and stenosis, 2 for combined mitral stenosis and regurgitation with aortic insufficiency, and 1 for mitral and tricuspid regurgitation.
RESULTS: Mean age at operation was 13.5 ± 4 years. Three patients required operation during the acute phase of rheumatic fever (< 6 weeks), 2 during the subacute phase (< 6 months), and 21 during the chronic phase after the episode of rheumatic fever (6.7 ± 3 years). Mitral valve repair was possible in 19 of 22 patients who required mitral operation. Aortic valve repair was possible in 4 patients whereas replacement was necessary in 9, including 2 Ross procedures. No operative deaths were recorded and 2 late deaths occurred at 4.6 and 10 years. Actuarial survival was 94% at 5 years and 78% at 10 years. Six patients required reoperation; actuarial freedom from reoperation was 78% at 5 years, 65% at 10 years, and 49% at 15 years. All survivors are in New York Heart Association class I or II.
CONCLUSIONS: Children with RHD in the United States uncommonly require valve operation. Mitral repair with a technique that allows annular growth is possible in most children with good long-term functional results. Long-term surveillance of children with RHD is necessary because of the possible need for late valve operation.
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Introduction
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Rheumatic fever (RF) and rheumatic heart disease (RHD) remain a worldwide health issue and a major cause of cardiovascular death in children and young adults in developing countries [1, 2]. Once widespread in the United States, the incidence of RF declined during the 1960s and 1970s to the point of near elimination [3, 4]. Recent reports of outbreaks of acute RF across the United States bring to light that RHD has not been entirely eradicated [5–9]. Although much is known about surgical intervention in adults with RHD worldwide, less is known about the incidence and characterization of surgical intervention for RHD in children, particularly in North America where treatment for streptococcal infections is common and access to medical care is more likely than in other less-developed areas of the world.
This review is in response to the resurgence of RF and RHD observed in the Intermountain West with respect to the accumulation of patients requiring surgical intervention during the childhood years. We have reviewed our 18-year experience dating from 1985 when the first resurgence of RF was seen in Utah [10]. We paid particular attention to the type of valve intervention needed and the long-term results of current surgical techniques.
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Material and Methods
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Patients
The pediatric cardiology RF database at Primary Children's Medical Center and the University of Utah was reviewed to identify children diagnosed with RF from January 1985 through June 2003 using recognized Jones criteria [11, 12]. This retrospective study protocol was approved by the Institutional Review Board at Primary Children's Medical Center and the University of Utah. Patient records were reviewed to identify all patients with rheumatic carditis who subsequently underwent surgical intervention before 21 years of age. Patient charts were examined for patient age at the time of operation, date of RF diagnosis, specific valvular abnormality, echocardiographic findings, indications for valve operation, date of death or reintervention, and the type of valve operation.
The medical records of 596 children younger than 21 years diagnosed with RHD between 1985 and 2003 were retrospectively reviewed. Rheumatic carditis was diagnosed in 366 patients (61.4%). Twenty-six (7.1%) of these patients subsequently required operation for rheumatic valve disease. These 26 patients comprised the patient cohort in this review. Indications for valve operation are shown in Table 1. Three patients required operation during the acute phase of RF (< 6 weeks) and 23 during the subacute (< 6 months) or chronic phase (mean 4.8 ± 3.8 years) after the episode of RF.
Preoperative Assessment
Two-dimensional and pulsed Doppler echocardiography was performed preoperatively from standard views. The anatomy of the mitral apparatus was evaluated for annular dimension, coaptation of the mitral valve leaflets, commissural fusion, leaflet thickening and mobility, and chordal elongation or shortening. The severity of the mitral regurgitation was assessed using color Doppler [13]. Since 1993, transesophageal echocardiography was performed intraoperatively for all patients to assess both repair potential and operative outcome.
Surgical Technique
In all cases a median sternotomy incision was used. Cardiopulmonary bypass was instituted with aorto-bicaval cannulation. Cold blood antegrade cardioplegia was used in most cases, with retrograde cardioplegia administration in individual cases. The mitral valve was approached through a left atriotomy in most cases. Valve function was accessed by visual inspection and "floating" of the valve with iced saline. Mitral valve reconstructive techniques have been described previously [14, 15]. Rumel debridement [16] of thickened leaflets consisted of using a scalpel to make a partial-thickness incision in the anterior leaflet 1 mm from and parallel to the annulus (Fig 1). The fibrous layer was then peeled and dissected from the leaflet carefully so as to reduce the anterior leaflet thickness and improve mobility and pliability. An annuloplasty ring was used when the annulus would accept an "adult"-sized prosthesis (generally > 26 mm). Commissuroplasty was used when further growth of the annulus was anticipated and a complete annuloplasty ring was thought not to be indicated. This method consisted of stitches taken at the commissures to reduce the overall annular size and to bring the anterior leaflet more in apposition with the posterior leaflet (Fig 2). When repair was not feasible, mitral valve replacement with a St. Jude Medical (St. Jude Medical, Inc, St. Paul, MN) mechanical valve was performed.
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Fig 1. Commissurotomy and anterior mitral debridement for predominant mitral stenosis. The commissures are incised to allow full valve opening (top). The debridement is begun by incising 1 mm from the anterior annulus using a scalpel and incising approximately half the depth of the thickened leaflet (middle). The leaflet is thinned to the coaptation edge by "peeling" the fibrotic and scarred tissue off of the anterior leaflet (bottom).
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Fig 2. Commissuroplasty. For small children without an adult-sized annulus and predominantly mitral regurgitation, a commissuroplasty is performed to reduce the annular size and allow better coaptation of the anterior leaflet.
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Table 2 lists the various repair techniques used to treat mitral valvular heart disease in the patients. Mitral valve repair was possible in 19 of 22 patients who required a mitral operation. Some patients had more than one repair procedure. Commissurotomy was performed in 6 (32%) of the 19 patients, Rumel debridement of the leaflets in 5 (26%), and commissuroplasty in 3 (16%). Mitral valve prosthetic ring annuloplasty was performed in 10 (53%) patients. The mean age of these patients at the time of the annuloplasty was 14.3 ± 3.8 years (range 10.0 to 20.9 years); their mean weight was 65.1 ± 14.3 kg, and the mean body surface area was 1.6 ± 0.42 m2. The average size of the annuloplasty ring was 29.4 ± 1.6 mm. (range 28 to 32, median 29). Partial posterior annuloplasty was performed in 2 (11%) patients. After the repair, the degree of mitral regurgitation as assessed by intraoperative transesophageal echocardiogram was none in 5, trace in 6, and mild in 8. Mitral valve repair was not possible in 3 patients; therefore, 2 of those patients underwent mechanical valve replacement and the third patient underwent replacement with a porcine heterograft valve.
Aortic valve repair was performed with techniques described by Duran and colleagues [17, 18]. Aortic valve replacement was performed using a St. Jude Medical mechanical valve, a tissue valve, or a pulmonary autograft. Aortic valve repair was possible in 4 patients. The average age of these patients at the time of operation was 12.3 ± 4.1 years (range 6.2 to 15.6 years). Repair consisted of a combination of commissuroplasty techniques and pericardial patch augmentation of aortic valve leaflets [17, 18]. Nine patients required initial aortic valve replacement at an average age of 14.2 ± 2.0 years (range 10.9 to 19.3 years). A mechanical valve was inserted in 5 patients, a porcine valve in 1 patient, and an aortic homograft in 1. The remaining 2 patients underwent a pulmonary autograft procedure.
Follow-up
All patients were followed up by clinic visits or telephone contact during the months of November or December 2003. The need for late reintervention was determined by the patient's cardiologist using clinical features and symptoms, echocardiographic findings, and when necessary, cardiac catheterization.
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Results
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Among the 26 study patients, no operative deaths and 2 (7.7%) late deaths were noted. The first patient died 4.6 years after aortic valve replacement and mitral valve repair secondary to injuries after a motor vehicle accident. A second patient with diabetes and a mechanical mitral valve died 10 years after the initial operation due to complications of a cerebral vascular accident secondary to thrombus formation on the prosthetic valve. Actuarial survival was 94% ± 6% at 5 years and 78% ± 15% at 10 years (Fig 3).
Reoperation occurred in 6 (23%) patients. The average time to reoperation was 5.3 ± 3.3 years. One patient who had undergone a mitral commissuroplasty and tricuspid valvuloplasty required placement of a porcine mitral valve for progression of mitral regurgitation 28 months after the operation. A second patient who had a valvuloplasty repair of the mitral and aortic valve had progressive valve insufficiency and required mitral and aortic valve replacement at 30 months. A third patient required an aortic and mitral valve replacement and tricuspid valvuloplasty 35 months after a Ross procedure and mitral valve annuloplasty. Another patient had mechanical aortic and mitral valves inserted 51 months after the original porcine aortic and mitral valves were placed. One patient with an aortic mechanical valve underwent aortic valve replacement with an aortic stentless valve because of subvalvar stenosis from pannus ingrowth of the original valve 119 months after the operation. For the final patient requiring reoperation, a thrombus developed on a mechanical mitral valve that required replacement with a second mechanical valve 120 months after the original operation. The overall actuarial freedom from reoperation was 78% ± 7% at 5 years, 65% ± 13% at 10 years, and 49% ± 21% at 15 years (Fig 4).
Functional results showed all survivors to be in New York Heart Association class I or II. All but 1 survivor remained in sinus rhythm (23/24, 96%). Three survivors (3/24, 12.5%) had thromboembolic complications, two of which were related to prosthetic mechanical valves.
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Comment
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This series represents one of the few cohorts of pediatric RF examining the need for valve operation in a developed country. In 1987 we reported a resurgence of RF in the Intermountain area of the United States [10]. Between 1985 and 2003, we diagnosed and followed nearly 600 patients who presented with RF before the age of 21 years, 366 of whom (61.4%) had carditis. Patients with RF in our series mirrored those seen in other countries with a similar incidence of carditis at diagnosis of approximately 60% to 70% [19, 20]. However, RHD in the United States seems to be associated with a lower incidence of valve operation in children as compared with other countries. Of these 366 in our series, 26 (7.1%) required operation for rheumatic valve disease. In an aboriginal cohort studied in the Northern Territory of Australia, 6 of 33 (18%) pediatric patients followed for 10 years required valve operation and another 2 patients died of rheumatic valve disease without operation [21]. In another series from Lebanon, the incidence of valve operation in a somewhat selected series of children was 31% [22]. These differences are likely due to better access to medical treatment and penicillin during primary streptococcal infections in developed countries and the fact that more patients receive secondary penicillin prophylaxis after an episode of RF, thereby decreasing recurrences and valvular damage and the need for valve operation.
Our own approach has been to maintain all patients with documented RHD, with or without valve operation, on long-term penicillin at a dose of 250 mg twice daily indefinitely to prevent recurrences and hopefully prevent the need for subsequent operation. Rheumatic fever has long been considered to be primarily a disease found in low socioeconomic communities and developing countries. However, this report and others delineating outbreaks of RF in the United States involving all socioeconomic groups of children, demonstrate the continued need for accurate diagnosis, treatment, and careful surveillance due to the late sequelae and possibility of valve intervention.
The pathology of RHD is well described and appears to be similar no matter whether RHD occurs in a developed or undeveloped part of the world. Thorough documentation describes acute rheumatic mitral disease as characterized by mitral annular dilation, chordal elongation, mitral valve prolapse, and predominantly mitral valve regurgitation [23]. In our series this was confirmed in that all 3 patients with operation during the acute phase; both patients operated on during the subacute phase had pure mitral regurgitation without evidence of mitral stenosis. As time goes on and recurrences and scarring occurs during the chronic phase, mitral stenosis becomes more predominant in older patients [24]. This scarring and stenosis occurs more than 20 to 40 years later, so most pediatric series involve patients with predominantly mitral regurgitation [24], as we saw in our series. Additionally, chronic aortic insufficiency occurs in children less often than mitral disease and occurs because of leaflet contraction and scarring with resulting insufficiency [21, 22]. The frequency of aortic valve disease appears to be about 25% to 30% of all children with severe rheumatic valve disease [21, 22, 25] and occurred in 12 patients in our series (46%). Finally, tricuspid disease was relatively uncommon in our series, probably because operation for mitral disease occurred relatively early in the course of RHD in this series, before significant mitral stenosis and long-standing pulmonary hypertension and secondary tricuspid valve regurgitation could develop.
Of the 26 patients with rheumatic carditis requiring valve operation, 22 required mitral valve procedures in our series. Mitral valve repair was possible in most (19/22) patients, whereas only 3 patients underwent primary mitral valve replacement. Only 1 patient required prosthetic mitral valve replacement since the first year of our surgical experience, thus underscoring our bias that most mitral valves in pediatric RHD are repairable. Debridement or thinning of the anterior leaflet as originally described by Rumel and associates in 1969 [16] was performed in 26% (5/19) of the patients undergoing mitral repair. This particular technique has been rarely used by others over the years, but we think it offers a safe and effective method to improve pliability and opening of the anterior leaflet of the mitral valve in patients who have evidence of mitral stenosis. We prefer an open commissurotomy over closed techniques because the open method is more accurate and allows an annuloplasty ring to be placed at the same time if the annulus is an appropriate size to accept an adult-sized ring. Mitral annuloplasty helps to prevent annular dilatation and reduces the incidence of mitral regurgitation [26, 27], but is only applicable in children if the annulus is fully grown (> 28 to 30 mm). Ten patients had echocardiographic and intraoperative evidence of annular dilatation. Chauvaud and colleagues [26] reported a 27% reoperation rate in patients with annular dilatation in which a prosthetic ring was not used at the initial operation. In our series, 2 patients (aged 6 and 6.5 years) underwent a partial posterior annuloplasty. In these patients, the degree of annular dilatation was not great enough to permit placement of an adult-sized annuloplasty ring. By not fixing the annulus with a circumferential ring, appropriate annular growth should be maintained. Although follow-up was short (6 months and 3 years), neither patient showed evidence of annular dilatation or worsening mitral regurgitation. Commissuroplasty (Fig 2) to shorten the posterior leaflet length and increase the area of leaflet coaptation was performed in 3 patients. Others have also reported good results with mitral valve commissuroplasty in RHD [27–29].
Aortic valve procedures were performed on half of our patients. Aortic valve repair was possible in one third of our patients who required aortic valve operation. Repair procedures included pericardial patch augmentation of the aortic valve leaflets with commissuroplasty, commissuroplasty with leaflet shortening, and commissuroplasty alone [16, 17]. Aortic valve repair has the advantage of permitting continued growth of the aortic valve and the avoidance of anticoagulation. Only 1 patient required reoperation at 2.5 years after the initial procedure for progressive aortic insufficiency. There was concern that this patient had not been compliant with regard to continuing antibiotic prophylaxis therapy. Others have reported good results using aortic cusp extension valvuloplasty techniques in patients with rheumatic valvular disease [17, 18, 30, 31]. Although long-term results are yet to be seen, aortic cusp extension valvuloplasty may delay the need for valve replacement until an adult-sized valve can be used. Aortic valve repair was not possible in 9 cases, the majority of which, similar to mitral valve replacement, were in the earlier years of our experience. Of note is that 2 patients underwent the Ross operation with 1 patient requiring reoperation to replace both the pulmonary autograft and pulmonary allograft nearly 3 years after the Ross operation for progressive autograft valve insufficiency. The second patient did well and had echocardiographic evidence of mild-to-moderate aortic insufficiency at 7.4 years follow-up. Choudhary and colleagues [32] showed that the pulmonary autograft is susceptible to rheumatic involvement, and that young age (< 30 years) and associated mitral valve disease were significant risk factors for autograft failure. Others have also advocated abandoning the use of pulmonary autografts in young patients with rheumatic heart valve disease [33]. Our limited experience would support this conclusion. At the very least, we would recommend proceeding with caution in utilizing the Ross procedure in a patient with RHD.
Limitations of this study included the retrospective nature and that a relatively small number of patients were involved in comparison with studies originating outside the United States. The small numbers make accurate assessment of the need for late reoperation difficult because even fewer patients were followed beyond 10 years. The study spanned 18 years, during which time valvuloplasty techniques markedly improved. Valves that were replaced early in our series may have been amenable to repair using current valvuloplasty techniques.
Although the total number of patients requiring surgery is small, this series allows us to make some conclusions regarding RHD currently in the United States. First, RF and rheumatic valve disease persist in the United States, although the numbers are smaller than seen in other parts of the world. Secondly, valve pathology in children is predominantly mitral regurgitation and appears identical to that seen in other parts of the world. Currently available valve repair techniques can be performed with good results; continued follow-up is necessary because of the possibility of late reoperation.
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References
|
|---|
- Olivier C. Rheumatic fever—is it still a problem? J Antimicrob Chemother. 2000;45(Suppl):13–21[Abstract]
- Stollerman GH. Rheumatic fever. Lancet. 1997;349:935–942[Medline]
- Gordis L. The virtual disappearance of rheumatic fever in the United States: lessons in the rise and fall of disease. T. Duckett Jones memorial lecture. Circulation. 1985;72:1155–1162[Free Full Text]
- Bisno AL. The resurgence of acute rheumatic fever in the United States. Annu Rev Med. 1990;41:319–329[Medline]
- Ayoub EM. Resurgence of rheumatic fever in the United States. The changing picture of a preventable illness. Postgrad Med. 1992;92:133–136
- Leggiadro RJ, Birnbaum ST, Chase NA, Myers LK. A resurgence of acute rheumatic fever in a mid-South children's hospital. South Med J. 1990;83:1418–1420[Medline]
- Zangwill KM, Wald ER, Londino AV Jr. Acute rheumatic fever in western Pennsylvania: persistent problem into the 1990s. J Pediatr. 1991;118:561–563[Medline]
- Veasy LG, Tani LY, Hill HR. Persistence of acute rheumatic fever in the intermountain area of the United States. J Pediatr. 1994;124:9–16[Medline]
- Hosier DM, Craenen JM, Teske DW, Wheller JJ. Resurgence of acute rheumatic fever. Am J Dis Child. 1987;141:730–733[Abstract/Free Full Text]
- Veasy LG, Wiedmeier SE, Orsmond GS, et al. Resurgence of acute rheumatic fever in the intermountain area of the United States. N Engl J Med. 1987;316:421–427[Abstract]
- Jones criteria (revised) for guidance in the diagnosis of rheumatic fever. Circulation 1984;69:204A–8A
- Guidelines for the diagnosis of rheumatic fever. Jones criteria, 1992 update. Special Writing Group of the Committee on Rheumatic Fever, Endocarditis and Kawasaki Disease of the Council on Cardiovascular Disease in the Young of the American Heart Association. JAMA 1992;268:2069–73 (published erratum appears in JAMA 1993;269:476)
- Wu YT, Chang AC, Chin AJ. Semiquantitative assessment of mitral regurgitation by Doppler color flow imaging in patients aged < 20 years. Am J Cardiol. 1993;71:727–732[Medline]
- Carpentier A. Cardiac valve surgery: the "French correction". J Thorac Cardiovasc Surg. 1983;86:323–337[Medline]
- Chauvaud S, Fuzellier JF, Berrebi A, Deloche A, Fabiani JN, Carpentier A. Long-term results of reconstructive surgery in rheumatic mitral valve insufficiency. Circulation. 2001;104(Suppl 1):I-12–15
- Rumel WR, Vaughn CC, Guibone RA. Surgical reconstruction of the mitral valve. Ann Thorac Surg. 1969;8:289–296[Medline]
- Duran C, Kumar N, Gometza B, al Halees Z. Indications and limitations of aortic valve reconstruction. Ann Thorac Surg. 1991;52:447–454[Abstract]
- Duran CM, Gometza B, Kumar N, Gallo R, Martin-Duran R. Aortic valve replacement with freehand autologous pericardium. J Thorac Cardiovasc Surg. 1995;110:511–516[Abstract/Free Full Text]
- Ferguson GW, Shultz JM, Bisno AL. Epidemiology of acute rheumatic fever in a multiethnic, multiracial urban community: the Miami-Dade County experience. J Infect Dis. 1991;164:720–725[Medline]
- Tolaymat A, Goudarzi T, Solar GP, Miller RH, Ayoub EM. Acute rheumatic fever in north Florida. South Med J. 1984;77:819–823[Medline]
- Carapetis JR, Kilburn CJ, MacDonald KT, Walker AR, Currie BJ. Ten-year follow-up of a cohort with rheumatic heart disease (RHD). Aust N Z J Med. 1997;27:691–697[Medline]
- Bitar FF, Hayek P, Obeid M, Gharzeddine W, Mikati M, Dbaibo GS. Rheumatic fever in children: a 15-year experience in a developing country. Pediatr Cardiol. 2000;21:119–122[Medline]
- Marcus RH, Sareli P, Pocock WA, et al. Functional anatomy of severe mitral regurgitation in active rheumatic carditis. Am J Cardiol. 1989;63:577–584[Medline]
- Marcus RH, Sareli P, Pocock WA, Barlow JB. The spectrum of severe rheumatic mitral valve disease in a developing country. Correlations among clinical presentation, surgical pathologic findings, and hemodynamic sequelae. Ann Intern Med. 1994;120:177–183[Abstract/Free Full Text]
- John S, Ravikumar E, Jairaj PS, Chowdhury U, Krishnaswami S. Valve replacement in the young patient with rheumatic heart disease. Review of a twenty-year experience. J Thorac Cardiovasc Surg. 1990;99:631–638[Abstract]
- Chauvaud S, Perier P, Touati G, et al. Long-term results of valve repair in children with acquired mitral valve incompetence. Circulation. 1986;74:I104–109
- Sulayman R, Mathew R, Thilenius OG, Replogle R, Arcilla RA. Hemodynamics and annuloplasty in isolated mitral regurgitation in children. Circulation. 1975;52:1144–1151[Abstract/Free Full Text]
- Choudhary SK, Talwar S, Dubey B, Chopra A, Saxena A, Kumar AS. Mitral valve repair in a predominantly rheumatic population. Long-term results. Tex Heart Inst J. 2001;28:8–15[Medline]
- Stevenson JG, Kawabori I, Morgan BC, Dillard DH, Merendino KA, Guntheroth WG. Rheumatic mitral regurgitation. The case for annuloplasty in the pediatric age group. Circulation. 1975;52(Suppl):I-49–51
- Grinda JM, Latremouille C, Berrebi AJ, et al. Aortic cusp extension valvuloplasty for rheumatic aortic valve disease: midterm results. Ann Thorac Surg. 2002;74:438–443[Abstract/Free Full Text]
- Kalangos A, Beghetti M, Baldovinos A, et al. Aortic valve repair by cusp extension with the use of fresh autologous pericardium in children with rheumatic aortic insufficiency. J Thorac Cardiovasc Surg. 1999;118:225–236[Abstract/Free Full Text]
- Choudhary SK, Mathur A, Sharma R, et al. Pulmonary autograft: should it be used in young patients with rheumatic disease? J Thorac Cardiovasc Surg. 1999;118:483–491[Abstract/Free Full Text]
- Al-Halees Z, Kumar N, Gallo R, Gometza B, Duran CM. Pulmonary autograft for aortic valve replacement in rheumatic disease: a caveat. Ann Thorac Surg. 1995;60(Suppl):S172–176
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Abstract
Introduction
