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J Thorac Cardiovasc Surg 2007;134:902-908
© 2007 The American Association for Thoracic Surgery
Surgery for Acquired Cardiovascular Disease |
Damascus University Cardiovascular Surgical Center, Mezza, Damascus, Syria.
Read at the Eighty-sixth Annual Meeting of The American Association for Thoracic Surgery, Philadelphia, Pa, April 29-May 3, 2006.
Received for publication May 29, 2006; revisions received April 29, 2007; accepted for publication May 11, 2007. * Address for reprints: Sami Kabbani, MD, Damascus University Cardiovascular Surgical Center, Mezza Str, PO Box 2837, Damascus, Syria. (Email: dam-uncv{at}net.sy).
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Abstract |
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Methods: Between July 14, 1997, and August 8, 2004, a total of 92 patients with irreparable mitral valve disease underwent mitral valve replacement with the pulmonary autograft encased within a Dacron tubing for support. In 4 patients, the autograft had to be sacrificed at the initial operation. Of the remaining 88 patients, 62 were female, and the age ranged from 4 to 64 years (mean 39 years). Eighty-six patients had rheumatic mitral disease, and 2 patients had congenital mitral disease.
Results: Operative transesophageal echocardiography initially showed adequate valve characteristics (mean valve area 2.8 cm2, mean gradient 3.9 mm Hg, no significant regurgitation) in all 88 patients. Operative mortality was 4.6%, and late mortality definitely related to the operation was 7.9%. Four patients were lost to follow-up; the mean follow-up was 60 months. Progressive regurgitation and stenosis developed in 9 patients over 2 to 5 years, 4 of whom had their grafts explanted. The autograft was explanted in 1 patient because of endocarditis. Mild pulmonic stenosis developed in 3 patients, and critical pulmonic stenosis developed in 1 patient. At 5 years follow-up, freedom from degeneration was 93.4%, freedom from reoperation was 94.2%, and freedom from all death was 86.0%.
Conclusion: Although the Ross II operation is difficult and harbors significant risk, it remains an option for patients with irreparable mitral disease who have a long life expectancy and who cannot be placed on lifelong anticoagulation.
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Introduction |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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In this endeavor we hoped to achieve for the mitral valve what has already been accomplished for the aortic valve.2 This study is an analysis of the outcome of 92 pulmonary autografts implanted in the mitral position during a 7-year period, ending in August of 2004. |
Materials and Methods |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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Because of a temporary lack of pulmonary homografts and xenografts, as well as a precipitous decrease in available mitral candidates, we were unable to perform this procedure for approximately 8 months after August 8, 2004. After this date, the operation was resumed on a sporadic basis as allowed by patients’ availability. In this report we present the analysis of our first 92 patients, because they belonged to a single time frame.
Exclusion criteria were significant aortic valve disease, pulmonary artery systolic pressure greater than 90 mm Hg, previous cardiac operation or pericardial adhesions found at operation, annular mitral calcification, and ejection fraction less than 30%.
The mitral pulmonary autograft had to be sacrificed during the initial operation in 4 of the 92 patients, so the total number of patients reviewed was 88.
The male-to-female ratio was 26:62, and the patients were aged between 4 and 64 years, with a mean of 39.2 years (±11.2 years). Figure E1 depicts the age distribution according to 10-year groups.
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2/4) of tricuspid regurgitation, and 41 patients had insignificant (<1.5/4) aortic regurgitation. Fifty patients were in atrial fibrillation, and 38 patients were in sinus rhythm. Twenty-eight patients underwent cardiac catheterization to rule out coronary artery disease. Most patients (81) were in New York Heart Association classes II and III, and preoperative echocardiography showed a mean left atrial size of 6.0 cm. Table E1
shows some of the preoperative echo/Doppler data.
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were strictly adhered to. The ratio of patients actually undergoing the Ross II procedure to those undergoing the operation with the intent of performing it in case the mitral valve was found irreparable was 1 to 3.
Details of the operation were described in a previous report.4 The operation in principle involves encasing the pulmonary autograft within a Dacron tubing of appropriate size for support before suturing its distal (pulmonary) end to the excised mitral valve annulus.
All operations were conducted under cardiopulmonary bypass, moderate hypothermia, and blood cardioplegia. In the early stages of our experience we favored a transseptal approach, but lately we have relied on a standard left atriotomy, except when the left atrium is small (<5 cm).
Once the mitral valve was found beyond repair and a decision was made to operate, the pulmonary artery was taken down and replaced with a suitable tissue substitute, as in the classic Ross operation. Twenty-nine cryopreserved pulmonary homografts, 56 pulmonary xenografts (Ross, CryoLife, Inc, Kennesaw, Ga), and 3 cryopreserved aortic homografts were used for pulmonary trunk replacement.
While the surgeon replaced the pulmonary artery, the co-surgeon inserted the trimmed pulmonary autograft inside a piece of rigid Dacron tubing and sewed the proximal and distal ends to the tubing edges, guided by premarked lines. The size of the Dacron tubing was chosen to be slightly larger than the eye-balled size of the pulmonary artery (a 1-inch long piece of size 30-mm tubing was used in most patients). In the 2 children with congenital mitral lesions, the tubing was slit (along 1 side in 1 patient and along 2 sides in 1 patient) to allow for mitral annular growth with the growth of the child. The mitral valve was excised, preserving as much of the native subvalvular apparatus as possible, and the left atrial appendage was excluded.
Since December of 2002, microwave ablation (AFx, Inc, Fremont, Calif) has been used in all of our patients with mitral disease and atrial fibrillation.5 Eleven patients in this series had atrial fibrillation ablation. The distal end of the autograft/Dacron conduit was finally sutured to the mitral annulus, the tricuspid valve was repaired if necessary, and the atriotomy was closed. Intraoperative transesophageal echocardiography (TEE) was obtained when the heart resumed its activity to ensure that results were acceptable before decannulation and chest closure.
We chose to place the pulmonary autograft conduit in the atrium rather than the ventricle because the design of the inverted pulmonary autograft does not lend itself to having its distal (pulmonary truck) end sutured to the papillary muscles, as is the case with the mitral homograft. Further, if most of the autograft/Dacron tubing is placed in the ventricle it is bound to cause some left ventricular outflow obstruction, as was found in the early experiments replacing the mitral valve with the pulmonary-autograft or aortic homograft, before Hubka6 introduced the concept of placing the conduit completely in the left atrium.
The "Achilles heel" of this operation has been conduit obstruction in some patients because of the angulation of the soft tubing material, necessitating immediate reoperation for correction or re-replacement. This potential problem has been managed in a variety of ways over the years.7-9
In the first 36 patients, a pericardial patch was used to anchor the proximal edge of the autograft/Dacron conduit to the adjacent atrial wall ("top-hat" configuration), at the same time covering foreign material and creating, in essence, a new left atrial floor, a method originally advocated by Yacoub and Kittle.10 Because this method did not seem to prevent Dacron tubing collapse, as we accidentally found out, and it became obvious to us that the firmness of the Dacron material played a major role in preventing the iatrogenic atrioventricular obstruction, we began using pericardium simply to cover foreign material as a "miniskirt" to save operative time and decrease operative risk.4 We also avoided modern soft varieties of Dacron and adhered to using the original resilient Dacron tissue when it was available, or autoclaving the soft varieties with albumin when it was not, to give them the required resilience. After 10 patients we abandoned the use of pericardium altogether to simplify the operation even further. Finally, because we were having difficulty obtaining old-fashioned Dacron tubings, and because there was kinking of the Dacron tubing even after autoclave treatment with albumin in 2 patients (possibly because the albumin coating dissolved later in warm blood), we returned to the "miniskirt" pericardial configuration.
We now use the "miniskirt" pericardial configuration4 using surgical glue (Bio Glue, CryoLife Inc, Kennesaw, Ga) in between the Dacron cloth and the pericardial tissue. This seems to give the conduit the firm texture required and has solved the potential problem of mitral obstruction.
Table E2 shows the details of the operation in this series. Figure E2, A to O, depicts the various stages of the operation as we now perform it. Figure E3 shows the Dacron conduit in a postoperative 4-chamber view echocardiogram and a typical 2-dimensional echocardiogram with color Doppler.
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Analyses were performed with Intercooled STATA version 9 (StataCorp, College Station, Tex) and the Statistical Package for the Social Sciences version 14 (SPSS Inc, Chicago, Ill). Survival curves were done using Kaplan–Meier in the Statistical Package for the Social Sciences version 14 (SPSS Inc). Autograft degeneration was designated as such when the mitral valve area was less than 1.5 cm2 and/or when regurgitation was more than 1.5/4 (1.5 corresponding to mild regurgitation). The mitral regurgitation was estimated by jet size and mental 3-dimensional jet reconstruction.
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Results |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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; mean 2.76 ± 0.45) and gradients (1.5–9 mm; mean 2.86 ± 0.6), and 0-trace mitral regurgitation (<1.5/4) in 86 patients. However, in 6 of the total 92 patients, starting with our 33rd case, a significant obstruction was detected by intraoperative TEE, which was caused by the shift from using old-fashioned Dacron tubing material to using modern soft tubing material. In 2 of these patients the problem was corrected at reexploration,7 but in 4 patients the autograft had to be explanted and replaced with a mechanical valve (bioprostheses were not available at our unit at the time). All 4 patients who underwent re-replacement of the autograft with mechanical prostheses are presently well. The problem of acute autograft stenosis was resolved with the use of surgical glue between the Dacron cloth and the pericardial wrap and has not recurred in our last 42 patients. Atrial fibrillation spontaneously changed to sinus rhythm postoperatively in 10 patients, and of 11 patients who had microwave ablation, 8 were successfully converted to sinus rhythm. Hospital mortality was 4.5% (4 patients). Table 1 lists the causes of mortality and major hospital events. The median intensive care unit stay was 2 days, and the median hospital stay was 7 days. There was 1 major hospital wound infection. The estimated pulmonary artery pressure on discharge from the hospital was 12 to 60 mm Hg with a mean of 27.4 ± 9.5. Table E3 shows the echo/Doppler findings on discharge from the hospital, which mimicked the findings of intraoperative TEE.
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Events during follow-up that were successfully managed included 1 late wound infection, 1 late pericarditis with tamponade, 3 episodes of major arrhythmia, and 1 major paravalvular leak that was repaired.
Nine patients showed evidence of progressive autograft regurgitation and/or stenosis, developing over 2 to 5 years. In 4 of these patients, the autografts had to be explanted. Gross examination of the explants showed the valve leaflets to be thickened and retracted in some cases. There were variable degrees of calcification, but no vegetations or thrombi. Microscopically, explanted valves showed neointima formation (pannus), fibrosis, disruption of elastic fibers, and scant and focal nonspecific chronic inflammation. Active rheumatic disease was suspected in 1 valve. The autograft was explanted in 1 patient because of endocarditis 3 years after the operation. There was no predilection of 1 of the 3 operative configurations to infection when compared with the others.
Various degrees of pulmonic stenosis developed in 4 patients’ pulmonary xenograft (3) or homograft (1) during the follow-up period. Only 1 patient (homograft, 5 years postoperative) now has significant (gradient > 60 mm Hg) stenosis and is awaiting reoperation.
A review of the 64 patients who are presently being followed up (Table E4) shows that most are in sinus rhythm, not taking anticoagulants, and in New York Heart Association functional class I or II. Three patients who were in atrial fibrillation were not receiving anticoagulation because there was a contraindication for it in 1 patient (in whom a subarachnoid hemorrhage developed) and noncompliance in 2 patients. The 3 patients received antiplatelet therapy. The echocardiographic findings of the 64 patients (Table E5) are, for the most part, acceptable.
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Analysis of the 3 operative techniques showed no statistically significant differences in the outcomes of death, degeneration, and reoperation. The use of Bio-Glue did not produce ill effects in any of the patients, and none of the patients in whom we used Bio-Glue underwent reoperation.
For the 4 patients who were lost to follow-up, the survival, degeneration, and reoperation curves show the events in all patients up to the 5-year point when the software excluded the patients lost to follow-up from the analysis.
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Discussion |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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There is no question that if mitral pathology can be corrected with reconstructive surgery, that option should be exercised, even if the pathology is rheumatic; for there is no mitral valve better than one’s own. Not every valve, however, can be repaired, and oftentimes a patient with a reconstructed rheumatic valve returns with a failed repair caused by recurrent rheumatic activity. Choosing the right mitral substitute for a particular patient is one of the most difficult decisions a cardiac surgeon working in a developing country has to make. In many of those countries proper anticoagulation is almost an impossibility,12 which makes mechanical prostheses, durable as they are, undesirable. In regard to tissue options, mitral homografts are not used by their original proponents because of lack of durability,13 and although the results of the quadrileaflet bovine valve (Quattro, St Jude Medical Inc, Minneapolis, Minn) are good at midterm,14 it is still not commercially available.
Stented bioprostheses have not demonstrated sufficient durability in young patients.15 Although the new generations of bioprostheses have fared much better, they start to degenerate quickly after their fifth year, especially in young patients.16-18 A comparison of our results with the results of second-generation bioprostheses (eg, Carpentier–Edwards supra-annular porcine [Edwards Lifesciences, Irvine, Calif], Carpentier-Edwards Perimount pericardial [Edwards Lifesciences], Hancock II bioprosthesis [Medtronic, Inc, Minneapolis, Minn], and Biocor porcine bioprosthesis [St Jude Medical, St Paul, Minn]) failed to show a statistical difference in survival or structural valve deterioration at 5 years. However, because the mitral-pulmonary autograft is made of viable autogenic tissue, we expect that it will be more durable in the long run and be comparable to the pulmonary autograft in the aortic position. Some of the early autografts implanted by Ross19 were functioning well 11 to 15 years after the initial operation.
Comparison of our reoperation (Figure E4) and survival (Figure E5) curves with those of the Ross registry (www.rossregistry.com) showed no statistically significant difference in either case.
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Children, young adults, and expectant mothers who need their mitral valves replaced are entitled to an option better than the mechanical valve, with its inherent thromboembolic risks and required taxing and relatively expensive lifelong anticoagulation, and the available biologic valves, with their insufficient long-term durability.
There have been some reservations with regard to using the Ross procedure in patients with rheumatic mitral disease.21,22 However, Al-Halees and colleagues21 concluded that it was inadvisable to offer the Ross operation to rheumatic patients with dilated aortic roots (28 mm) or to patients with concomitant mitral valve disease.21 Kumar and colleagues22 added the factor of age (<30 years), but this seems to be a point of contention (see "Discussion" in Kumar and colleagues’ article). Despite the rheumatic cause, we believe that young rheumatic patients deserve the benefit of the Ross II operation, because the alternative (mechanical or bioprosthetic mitral replacement) is not entirely satisfactory.
Although approximately half of the patients with mitral disease have concomitant atrial fibrillation, we should not accept a mechanical option because the risk of thromboembolism is much higher from the mechanical prosthesis than from lone atrial fibrillation, and there are fairly effective methods of atrial fibrillation ablation currently available.
The pulmonary autograft has unique salutary features, chief among which is its viability and nonthrombogenicity. Its stentless design also keeps mitral gradients at a minimum and accommodates the mitral annulus in the changes of the cardiac cycle. Its ability to grow with the child is yet to be proven, as well as its long-term durability, both of which need longer follow-ups.
We believe that there is a place for the mitral pulmonary autograft in the cardiac surgeon’s armamentarium. We see a clear benefit for it in the difficult congenital mitral lesion that cannot be repaired23 and in those patients who cannot take anticoagulants and have a long life expectancy ahead of them. It should be seriously considered in developing areas of the world where lifelong anticoagulation is not practical but where pulmonary homografts can somehow be obtained. It is unfortunate that only a few teams in the world have been willing to adopt the procedure.6,20,23-26
We think the best candidates for the Ross II operation are those who are in sinus rhythm, are aged less than 50 years, have a large enough left atrium (>5 cm), and have no important comorbid conditions.
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References |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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