Ann Thorac Surg 2000;69:739-742
© 2000 The Society of Thoracic Surgeons
Original Articles
Mitral valve replacement with homograft and Maze III procedure
Donald B. Doty, MDa,
Karikehalli A. Dilip, MDa,
Roger C. Millar, MDa
a Division of Cardiovascular and Thoracic Surgery, Department of Surgery, LDS Hospital, Salt Lake City, Utah, USA
Address reprint requests to Dr Doty, Department of Surgery, LDS Hospital, 324 Tenth Ave #160, Salt Lake City, UT 84103
e-mail: ldddoty{at}ihc.com
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Abstract
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Background. Mitral valve disease is often accompanied by atrial fibrillation, which may compromise the patient even after the valvular lesion has been repaired.
Methods. Three patients with rheumatic type mitral valve disease and chronic atrial fibrillation were treated by mitral valve replacement with cryopreserved mitral valve homograft and Maze III procedure, as a method to relieve both the valvular pathology and the rhythm disorder. The patients’ clinical courses have been followed for up to 1 year after operation.
Results. All patients survived operation, and all have normal sinus rhythm. None are taking cardiac medications.
Conclusions. Long-term treatment with warfarin should not be required, and other cardiac medicines may be eliminated following mitral valve replacement with homograft combined with Maze III procedure.
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Introduction
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Chronic atrial fibrillation is present in up to 60% of patients with rheumatic mitral valve disease [1]. This dysrhythmia is associated with significant morbidity, causing discomfort to the patient due to irregular cardiac rhythm, compromising cardiac hemodynamic performance. Long-term anticoagulant therapy with warfarin is usually prescribed to reduce formation of thrombus in the atrium, which accompanies atrial fibrillation and thereby reduces the risk of thromboembolism. Adequate treatment of mitral valve disease often does not relieve the cardiac rhythm disorder, and atrial fibrillation persists or recurs in up to 80% of operated patients [2, 3]. On the other hand, the Maze III procedure has provided an effective and permanent surgical cure for chronic atrial fibrillation [4].
Cardiac valve repair operations in patients with rheumatic mitral valve disease are often either unsuccessful from the outset, or offer only short-term relief because of destruction of chordae tendinea, which usually accompanies scarring of the leaflet tissue. Even medium-term performance of stent-mounted bioprostheses has been disappointing. Mechanical prosthetic heart valves all require anticoagulant therapy to reduce the risk of thrombosis or thromboembolism. Acar and associates [5] developed a reliable technique for implantation of a cryopreserved mitral valve homograft for replacement of the mitral valve. Short-term results appear promising, and anticoagulant therapy has not been employed without increased risk of thromboembolism. The natural mitral valve, transplanted as a homograft, may be ideal for replacement of the mitral valve, and when combined with the Maze III procedure, should result in excellent hemodynamic valve performance and restoration of normal sinus rhythm. Anticoagulant therapy, with its attendant risks, should not be required and other cardiac medications may be eliminated if this can be accomplished. This combined operation has been attempted and successfully accomplished in 3 patients.
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Patients and methods
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Patient 1
A 70-year-old woman had rheumatic mitral valve stenosis diagnosed in 1989 when she presented with atrial fibrillation. She presented in 1997 with embolism to the left renal artery. Anticoagulant therapy with warfarin was started. Nine months later, she suffered a transient cerebral ischemic attack, manifest by right-sided vision loss, while taking what was thought to be an adequate dose of warfarin. Prothrombin time was 13.1 seconds with an INR of 1.47. In August 1998, she had increasing symptoms of shortness of breath with exertion, and was found to have a persistent heart rate of 100 to 120 beats per minute in spite of therapeutic levels of digoxin and beta blocker medications. Echocardiogram showed mitral valve stenosis (valve area = 1.2 cm2) and insufficiency. Left ventricular size and function was normal but the left atrium was enlarged. Cardiac catheterization confirmed the diagnosis and demonstrated normal coronary arteries. Pulmonary artery pressure was 42/19. Mitral valve replacement with cryopreserved mitral valve homograft and Maze III procedure was performed on November 10, 1997. Aortic occlusion time was 185 minutes and cardiopulmonary bypass time was 242 minutes. Intraoperative echocardiography showed competence of the mitral valve homograft. Cardiac rhythm was paced for 5 days postoperatively. Warfarin therapy was resumed 2 days postoperatively. She was discharged home on the eigth postoperative day with normal sinus rhythm and a heart rate of 70 beats per minute. Echocardiography at 2 months showed trivial incompetence of the mitral valve, and a contractile atrium with transport function in a normal sinus rhythm. Warfarin was discontinued, and no cardiac medications were required. She was well 19 months after operation.
Patient 2
A 58-year-old man presented with a 4-year history of shortness of breath and fatigue with exertion, which had worsened during the past 1 year. He was a construction worker, and he had had rheumatic heart disease as a child. Atrial fibrillation had been diagnosed 10 years previously. He had been treated with warfarin. Echocardiography showed severe mitral valve stenosis with a valve area of 0.7 cm2. Cardiac catheterization showed normal coronary arteries. The patient expressed desire for a cardiac operation, which would eliminate the need for anticoagulant therapy because of his occupation in construction. Mitral valve replacement with cryopreserved mitral valve homograft and Maze III procedure was performed on January 8, 1998. Aortic occlusion time was 245 minutes and cardiopulmonary bypass time was 335 minutes. Intraoperative echocardiography showed trivial mitral valve incompetence. Cardiac rhythm showed complete heart block for 4 days. Temporary atrioventricular pacing was used for 4 days after operation. Atrioventricular conduction returned and atrial pacing was continued for 2 days. Atrial conducted rhythm with a heart rate of 76 beats per minute was present at discharge from the hospital on the seventh postoperative day. Warfarin therapy was resumed 2 days after operation. Echocardiography at 3 months showed competence of the mitral valve, and normal sinus rhythm with contractile atrium. Warfarin was discontinued, and no cardiac medications were required. He is well 17 months after operation.
Patient 3
A 46-year-old man was diagnosed in September 1997 with mitral valve stenosis, in addition to atrial fibrillation. He was admitted to a hospital in California with congestive cardiac failure in December 1997. Ventricular response in atrial fibrillation was greater than 150 beats per minute. Echocardiography revealed a mitral valve pressure gradient of 20 mm Hg, mitral valve area of 0.53 cm2, and pulmonary artery pressure of 43/30. He was treated with digoxin, metroprolol, and warfarin. The patient stopped taking these medications in January 1998. Shortness of breath with exertion and fatigue became progressively worse. He began to have orthopnea. He was admitted to LDS Hospital in April 1998. He had pulmonary edema and his heart rate was 110 beats per minute in atrial fibrillation. Cardiac catheterization showed a mitral valve mean gradient of 12 mm Hg and a mitral valve area of 1.09 cm2. Operation was planned knowing that the patient had uncontrolled heart rate, and was noncompliant with medical therapy. The mitral valve was replaced with a cryopreserved mitral valve homograft and a Maze III procedure was performed on May 13, 1998. Time for aortic occlusion was 244 minutes, and 307 minutes for cardiopulmonary bypass. Atrioventricular pacing was required because the heart rate was slow. Reentry for bleeding from the chest wall was required about 4 hours after operation. Cardiac rhythm was regular and of atrial origin, with a heart rate of 90 beats per minute by the day after operation. Warfarin therapy was resumed on the 2nd day after operation. Postoperative convalescence was routine, and he was discharged home 7 days after operation. He was in normal sinus rhythm, and breathing was much improved compared to preoperative levels. Echocardiography 2 months after operation showed mitral valve competence and contractile atria in normal sinus rhythm. Warfarin therapy was discontinued, and no cardiac medications were required. He is well 13 months after operation. He has extraordinary exercise ability, and is able to lift more than 400 lbs in weight training.
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Results
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A median sternotomy was performed. The Carpentier retractor system was used to obtain maximal exposure. Cardiopulmonary bypass was established using two cannulas for venous uptake with oxygenated blood returned to the ascending aorta. One venous cannula was placed directly in the superior vena cava at the pericardial reflection, the other was placed through the right atrium to the inferior vena cava. Perfusion temperature was maintained at 37°C so that the heart continued to beat while the right side portion of the Maze III procedure was performed (Fig 1). The right atrial appendage was excised, and an incision opened on the right atrial free wall as previously described [6]. A long incision from superior vena cava to inferior vena cava is made. The lower end is closed. An incision extending across the inferior right atrial free wall to the tricuspid annulus is made, with a cryolesion placed at the tricuspid annulus. The incision is partially closed. An incision is made on the medial aspect of the right atrium from the base of the appendage to the tricuspid annulus where a cryolesion is placed. The incision is closed. A perfusion cannula was placed in the coronary sinus, and cold blood cardioplegia solution infused to the coronary sinus after occlusion of the ascending aorta. The left side portion of the Maze III procedure was then performed. This included incision of the interatrial septum, and the encircling incision around the pulmonary veins (Fig 2A). The left atrial appendage was excised, and an incision from its base joined to the encircling incision (Fig 2B). This portion of the incision is closed. An incision of the left atrium to the midpoint of the posterior mitral valve annulus, exposing the coronary sinus, was made. Cryolesions were placed on the coronary sinus and the mitral valve annulus. The incisions in the left atrium were partially closed. The mitral valve was excised and chordae tendinea removed from the tips of the papillary muscles. The mitral valve was replaced with a cryopreserved mitral valve homograft using the technique previously described [7]. This technique includes fixation of the papillary muscles of the donor valve to the patient papillary muscles in side-by-side fashion using multiple stitches of fine monofilament sutures (Fig 3). The mitral valve homograft is attached to the annulus of the patient’s mitral valve using continuous stitches of polypropylene sutures. The mitral valve annulus is remodeled, and the repair supported with a Carpentier annuloplasty ring. Preliminary testing of competence of the mitral valve is done by infusion of saline solution into the left ventricle. The left atrial incisions for the Maze III procedure are closed. The aortic occlusion clamp is removed and the right atrial incisions are closed (Fig 4). Atrioventricular sequential cardiac pacing is usually required. Intraoperative echocardiography is performed when the heart is beating and ejecting. Postoperative care is routine. Warfarin therapy is started 2 days after operation, and it is discontinued 2 months later if normal sinus rhythm is maintained. Other cardiac medications are usually not required.
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Fig 1. Right side incisions, Maze III procedure. The right atrial appendage is excised, cryolesions placed and the incisions partially closed.
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Fig 2. (A) Left side incisions, Maze III procedure. This part of the procedure is done with the aorta occluded and the heart arrested. The septum is incised to the inferior aspect of the fossa ovalis and an encircling incision is made around the pulmonary veins. (B) Left side incisions, Maze III procedure, continued. The left atrial appendage is excised and an incision from its base made to the encircling incision. An incision is made to the midpoint of the mitral valve at the annulus posteriorly. A cryolesion is placed on the exposed coronary sinus. The incisions are partially closed.
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Fig 3. Mitral valve replacement with cryopreserved homograft. The papillary muscles are attached in side-by-side fashion using stitches of fine monofilament suture. The homograft is attached to the mitral annulus by continuous suture. The repair is supported by annuloplasty ring.
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Fig 4. Completion of the Maze III procedure. The encircling incision in the left atrium is closed. The atrial septum is reconstructed. The right atrial incisions are closed during reperfusion of the heart.
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Comment
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Atrial fibrillation is so common in patients with rheumatic-type mitral valve stenosis, that it is essentially part of the natural history of the disease [1]. The cardiac dysrhythmia reduces cardiac performance, and is often resistant to medical therapy. Medical control of ventricular response to atrial fibrillation may be difficult and bouts of tachyarrhythmia are common. The Maze III procedure has been applied to patients with atrial fibrillation and tachyarrhythmia with a high degree of success in restoring normal sinus rhythm and controlling heart rate. Cox and associates [8] reported 93% of 164 patients treated by the Maze III operation had normal sinus rhythm without antiarrhythmic medications during follow-up of 8.5 years. Medical therapy was required in 7% of the patients to maintain normal sinus rhythm. The operation involves extensive strategically located transmural incisions of the atria to interrupt macroreentry circuits responsible for atrial fibrillation. It can be a long and tedious operation, but with experience, technical facility can be mastered to accomplish the procedure in an orderly and efficient manner. Performing the right side portions of the operation with the heart perfused, substantially reduces cardiac ischemic time and allows concomitant procedures to be performed.
Replacement of the mitral valve with a mitral valve homograft is a concept dating back to the early days of cardiac operation. It seemed logical to surgeons that the natural mitral valve should be the ideal replacement device for the mitral valve. Anticoagulant therapy should not be necessary when normal human tissues are employed. Robicsek [9] reviewed historic experimental and clinical work, which preceded present success with the technique of mitral valve replacement with mitral valve homograft. Yankah and associates [10] called attention to the papillary muscle union of graft to recipient as "the locus minoris resistentiae," and recommended reinforcement of that site thoroughly. It was Acar and associates [5] who described a method for replacement of the mitral valve with homografts that was reproducible and provided consistent, secure attachment of the papillary muscles. The unique features of their approach included: side-by-side approximation of the papillary muscles [1]; multiple stitches of fine monofilament suture without pledget reinforcement to attach the papillary muscles [2]; and routine use of annuloplasty ring [3]. The advantages of the annuloplasty ring are: precise adaptation of the size of the annulus to that of the homograft [1]; the ring absorbs some of the mechanical stress exerted by ventricular contraction on the valve suture line [2]; and ring annuloplasty achieves a greater surface of leaflet coaptation which lowers tension on the subvalvular apparatus [3].
The combination of mitral valve replacement with mitral valve homograft and the Maze III procedure, seems to offer an ideal replacement device and the expectation that normal sinus rhythm would follow operation. This combination offers promise of correcting not only the cardiac valvular dysfunction, but also correcting disabling cardiac dysrrhythmia. With correction of mitral valve disease using biologic material and relief of atrial fibrillation, long-term anticoagulation, with its attendant problems and risks, should be eliminated. Experience in this small group of patients appears to confirm this hypothesis.
Indications for this combined operation would be in patients requiring mitral valve replacement where anticoagulant treatment in contraindicated, where it may be inadvisable because of occupation or avocation, and when the patient expresses strong reluctance to taking anticoagulant medications. An operation of this magnitude should probably not be done in patients with associated coronary artery, other valvular, or medical problems. It could be argued that other bioprostheses might have been used to reduce the complexity and length of operation, which attends the use of a mitral homograft. This argument might have applied specifically in patient 1, who was 70 years old at the time of operation. The only other bioprosthesis, available at that time for implantation in the mitral valve, was the standard stent-mounted porcine aortic valve, processed at low pressure in glutaraldehyde. Jamieson and associates [11] have shown the freedom from structural valve deterioration with this type of bioprosthesis is 35% (actuarial, 75% actual) at 15 years in patients age 61 to 70 years. For patients more than 70 years, freedom from structural valve deterioration at 15 years is 59% (actuarial, 89% actual). We thought these data favored use of a mitral homograft, though only short-term results are known with this device.
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Footnotes
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A video clip of this procedure can be viewed on the Internet at: http://www.sts.org/section/atsvideo/
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References
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Hirosawa K., Sekiguchi M., Kasanuki H. Natural history of atrial fibrillation. Heart Vessels 1987;2(Suppl):14-23.
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Papazoglou N.M. Atrial fibrillation and mitral stenosis. Circulation 1974;49:1020-1021.[Free Full Text]
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Kahn D.R., Kirsh M.M., Ferguson P.W., Sloan H.E. Cardioversion after mitral valve operations. Circulation 1967;35(Suppl 4):182-185.
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Cox J.L., Schuessler R.B., D’Agostino H.J., et al. The surgical treatment of atrial fibrillation. III. Development of a definitive surgical procedure. J Thorac Cardiovasc Surg 1991;101:569-583.[Abstract]
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Acar C., Tolan M., Berrebi A., et al. Homograft replacement of the mitral valve. Graft selection, technique and results in forty-three patients. J Thorac Cardiovasc Surg 1996;111:367-380.[Abstract/Free Full Text]
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Doty DB. Maze III procedure. In: Doty DB, ed. Cardiac surgery, operative technique. St. Louis: Mosby Inc, 1997:410–9.
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Doty D.B., Acar C. Mitral valve replacement with homograft. Ann Thorac Surg 1998;66:2127-2131.[Abstract/Free Full Text]
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Cox J.L., Schuessler R.B., Lappas D.G., Boineau J.P. An 8-year clinical experience with surgery for atrial fibrillation. Ann Surgery 1996;224:267-275.[Medline]
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Robicsek F. Homograft replacement of the atrioventricular valves. J Heart Valve Dis 1996;5:607-622.[Medline]
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Yankah A.C., Sievers H.H., Lange P.E., Bernhard A. Clinical report on stentless mitral allografts. J Heart Valve Dis 1995;4:40-44.[Medline]
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Jamieson W.R.E., Burr L.H., Janusz M.T., et al. Carpentier-Edwards standard, and supraannular porcine bioprostheses. Comparison of technology. Ann Thorac Surg 1999;67:10-17.[Abstract/Free Full Text]
Accepted for publication July 22, 1999.
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Top
Abstract
Introduction
