A Two-Year Experience with Supported

Transcription

1 THE ANNALS OF THORACIC SURGERY Journal of The Society of Thoracic Surgeons and the Southern Thoracic Surgical Association VOLUME 13 * NUMBER 2 - FEBRUARY A Two-Year Experience with Supported Autologous Fascia Lata for Heart Valve Replacement Donald N. Ross, F.R.C.S., Lorenzo Gonzalez-Lavin, M.D., and Harald Dalichau, M.D. ABSTRACT Over a two-year period 262 supported living fascia lata valves were implanted in 201 patients. Early results were satisfactory from the point of view of valve function. After several months it became obvious that autologous fascia lata valves behave very differently in each of the three positions. A critical analysis is presented of 193 valves that were available for follow-up. After two years experience with this method of valve replacement, it is the opinion of the authors that supported, living fascia lata valves are unsuitable for tricuspid valve replacement. In the mitral position they have shown an increasing incidence of systolic murmurs and evidence of regurgitation. The supported fascia valves have given the best functional results in the aortic position; however, not enough time has elapsed to assess their long-term function. R eports of the long-term function of fascia lata as an aortic valve substitute [8, 91 provided a stimulus for devising a valve of this tissue [4, 51 that could be used to replace diseased valves in the aortic, mitral, or tricuspid position and, consequently, would be applicable in multivalve disease. While our results have been adequate for valves in the aortic position, they have been less satisfactory for those in the mitral position and very disappointing in the tricuspid area. In view of the disparity in functional results obtained with these valves of the same design and material in From the Department of Surgery, Institute of Cardiology and National Heart Hospital, London, England. We acknowledge the assistance of Miss J. Brunner, R.N., for the diagrams appearing here, of Miss S. Thomas and Miss V. Adler, B.A., for preparation of the manuscript, and of Prof. Carlo De Gasperis for the histological study. Accepted for publication July 11, Address reprint requests to Dr. Conzalez-Lavin, Department of Surgery, National Heart Hospital, Westmoreland St., London, WlM 8BA, England. 97

2 ROSS, GONZALEZ-LAVIN, AND DALICHAU different positions, we would like to report our two-year experience with this method of valve replacement. -Material and Methods From April, 1969, to October, 1970, 262 supported fascia valves were implanted in 201 patients at the National Heart Hospital in London. Fiftyfive of the patients underwent multivalve replacement. One hundred and thirty-four valves were implanted in the aortic position, 112 in the mitral position, and 16 in the tricuspid position. Early results were satisfactory from the point of view of hospital mortality in patients undergoing single- and double-valve replacement (Table). Hospital mortality was high in patients undergoing triple-valve replacement, most likely owing to their precarious preoperative status; all patients having triple-valve replacement were in Class IV according to the New York Heart Association Functional Classification [2]. The valves functioned satisfactorily in the initial postoperative months; however, it soon became apparent that autologous fascia lata valves behave very differently in each of the three positions. Among the surviving patients, 193 valves were available for follow-up assessment. A critical analysis has been performed on these valves in each of the three positions. In the tricuspid position the fascia valves became regurgitant in 3 of 5 patients within three months of insertion, and replacement soon became necessary. At operation the most striking feature was the almost complete absence of functioning valve tissue; most of the cusps had rolled over the frame, leaving a large central opening for severe regurgitation. In the mitral position the fascia valves functioned well for the first six months; 92.8% were found to be competent at this time [3]. After eight HEART VALVE REPLACEMENT WITH SUPPORTED FASCIA LATA VALVES IN 201 PATIENTS AT THE NArIONAL HEART HOSPITAL, APRIL, 1969-APRIL, 1971 No. of Mortality (%) Procedure Pa tien ts Hospital Late Single-valve replacement Aortic Mitral Tricuspid Double-valve replacement Aortic & mitral Mitral & tricuspid Triple-valve replacement Total Total mortality 51 patients (25.3%) 98 THE ANNALS OF THORACIC SURGERY

3 Fascia Lata for Heart Valve Replacement months of implantation, an increasing incidence of systolic murmurs and increasing regurgitation in the valve became evident. Among patients who had mitral valve replacement, of the 78 available for study, 59 have been followed for at least one year, and there has been a definite increase in the incidence of systolic murmurs during this period. At discharge from the hospital, 9 patients had a diastolic murmur. By the end of the third postoperative month an additional 6 had developed a murmur, and at the end of 12 months a total of 20 of the 59 patients had a systolic murmur. Among the entire group of 78 mitral valves available for study, 5 valves have failed. Eleven others show trivial regurgitation, and 10 more have mild regurgitation. The degree of insufficiency was found to be moderate in the other 6. Therefore, among the 78 valves, 46 are competent and 32 are leaking to some degree or have failed (Fig. 1). In our experience, there has been a common mechanism of failure in all the supported fascia valves implanted in the mitral orifice. At reoperation, failed valves have usually been found to be regurgitant because of thickening and retraction of two of the cusps with partial fusion of the common commissure between them. The free edges of these affected cusps are rolled over and appear fixed in place by a layer of fibrin. The third cusp, or one of the three cusps, usually appears intact with normal striations and pliability (Fig. 2). Histopathological study of these valves has shown some changes in the fascia1 tissue, with decreased cellularity in the fascia itself and a well-defined layer of fibrin covering the fascia lata (Fig. 3). No other mechanism was responsible for the failure of mitral fascia valves; there were no peripheral leaks or detachment from the supporting frame, for example. Bacterial endocarditis did not play an important role in the failure of these mitral valves. The best results obtained thus far have been with fascia valves in the aortic position. During this two-year experience, 82 of the 110 aortic valves available for assessment have remained competent, 12 showed trivial regurgitation, and 6 had a mild degree of aortic insufficiency (Fig. 4). Eighty-four of the 110 patients have been followed for at least one year. At the time of discharge from the hospital, 8 had a diastolic murmur. By three months an FIG. 1. Degree of regurgitation and incidence of valve failure among the 78 patients with supported mitral valves durzng a two-year experience. No Mjtrg Reguqptation I 59% VOL. 13, NO. 2, FEBRUARY,

4 ROSS, GONZALEZ-LAVIN, AND DALICHAU A FIG. 2. (A) Atrial aspect of a failed value eight months after operation. The anterior cusp appears intact with normal striations and pliability. The other two cusps are retracted with almost complete disappearance of the common commissure between them. IB) Ventricular aspect of the same valve. additional 4 had developed a diastolic murmur, and, at the end of 12 months, a total of 15 had some degree of regurgitation. A comparison has been made between the mitral and aortic valves in patients followed for at least one year (Fig. 5). The functional results are far better in the aortic position. One particular problem with the valves implanted in the aortic position, however, has been the relatively high incidence of bacterial endocarditis. Among the 110 valves implanted in this area, 10 failed; and in 5 of these the cause of failure was bacterial infection with destruction of the valve. Comment It is difficult at present to know what is responsible for the differences in behavior of these valves in the three positions; however, one can speculate B FIG. 3. Histological section of one of the failed values showing a well-defined layer of fibrin covering the fascia lata. (Glutaraldehyde osmium fixation; X 3,000 before 50% reduction.) 100 THE ANNALS OF THORACIC SURGERY

5 Fascia Lata for Heart Valve Replacement Failed 9% (45 duetoel) FIG. 4. Degree of regurgitation and valve failure among 110 fascia lata valves in the aortic position. A twoyear experience. (B.E. = bacterial endocarditis.) that several factors contribute to the sustained function or failure of fascia lata when used as a trileaflet valve. First, accurate construction of the valve is of paramount importance. The slightest asymmetry of a cusp has proved to have significant hemodynamic consequences; studies in the pulse duplicator have shown asynchronous opening and closing of the cusp and rolling of the edges. Also, the varying thicknesses of the cusps most likely contribute to asynchronous motion of the leaflets, with the thinnest leaflet closing first. Second, valve hemodynamics in the different positions undoubtedly plays an important role in the continuing function or malfunction of the leaflets. For example, there is a considerable difference in the opening and closing pressures relative to inertia of the tissue in the three valve areas. In ordinary conditions at rest, the opening pressures acting on the tricuspid and mitral areas are low; with associated atrial fibrillation, the atrial thrust AORTIC MITRAL DISCHARGE ONE YEAR FIG. 5. Graphic comparison of the incidence of regurgitation between 59 mitral fascia lata valves and 84 aortic fascia lata valves followed for at least one year. (Abscissa represents time in months.) VOL. 13, NO. 2, FEBRUARY,

6 ROSS, GONZALEZLAVIN, AND DALICHAU is lost. Under these circumstances it is easy to visualize a situation, especially in the tricuspid area, in which the valve acts as an orifice only, with little or no flexing force on the tissue. As with many nonfunctional tissues, these valves were then likely to retract and fibrose. This phenomenon is well known to occur experimentally in homograft aortic valves; when placed in the descending aorta of dogs in the absence of aortic regurgitation, they commonly retract and cease to function [l, 61. In the aortic area there is a forceful pressure in systole and diastole flexing the cusps through a full range of motion, and this is perhaps the single most important factor contributing to the better function of the fascia lata leaflets in this site. The mitral valve occupies an intermediate position between the aortic and tricuspid valves with regard to opening and closing pressures, and its functional success seems to correspond. Asymmetrical or asynchronous closure of the leaflets may be another factor, since there is evidence that in the flow patterns of the left ventricle there is a predominant and preferential closing force on the anterior leaflet of the mitral valve 171. This leaflet appears to close earlier than the posterior one. In most of the failed fascia valves, in the mitral position the cusp adjacent to the aortic valve had persisted thin and pliable. In addition, the tissue itself can be criticized for being viable and therefore able to stimulate reaction with a possible autoimmune mechanism enhancing the deposition of platelets and fibrin on the outer layer of the valve, which later becomes organized, fixing the cusp in the open position. Another factor relating to the use of fascia lata is its lack of elastic properties compared with the natural valve. While this deficiency may be less important in the high-pressure aortic area, the use of nonelastic and relatively thick tissue in an area of low opening pressure is more likely to have a decisive effect on functional efficiency and consequently on long-term function. The best functional results so far have been with valves in the aortic position. These valves continue to function well, but not enough time has elapsed to assess the long-term results of this method of valve replacement. Frame-mounted fascia lata for tricuspid valve replacement has been almost totally disappointing in our experience, and we consider it to be unsuitable as used at present. In the mitral position, these valves give excellent functional results in the early months after operation, but they have shown an increasing incidence of systolic murmurs with the passage of time and there has been a significant number of valve failures. Our present policy has been to discontinue the use, in all areas, of living fascia lata as a valve substitute in view of the results obtained in the tricuspid and mitral positions. References 1. Brewin, E. G. The use of tissue transplants in the surgery of cardiac valvar disease: An experimental study. Guys Hosp. Rep. 105:328, THE ANNALS OF THORACIC SURGERY

7 Fascia Lata for Heart Valve Replacement 2. Criteria Committee, New York Heart Association, Inc. Diseases of the Heart and Blood Vessels: Nomenclature and Criteria for Diagnosis (6th ed.). Boston: Little, Brown, P Gonzalez-Lavin, L., Geens, M., and Ross, D. N. Mitral valve replacement with autologous tissue. Arch. Surg. 101:760, Ionescu, M. I., and Ross, D. N. Heart valve replacement with autologous fascia lata. Lancet 2:335, Ionescu, M. I., Ross, D. N., Deac, R., Grimshaw, V. A., Taylor, S. H., Whitaker, W., and Wooler, G. H. Autologous fascia lata for heart valve replacement. Thorax 25:46, Lam, C. R., Aram, H. H., and Munnell, E. R. An experimental study of aortic valve homografts. Surg. Gynecol. Obstet. 94: 129, Reid, K. G. Mitral valve action and the mode of ventricular filling. Nature (Lond.) 223: 1383, Senning, A. Results of Fascia Lata Reconstruction of the Aortic Valve. In Proceedings of the XVII Congress of the European Society of Cardiovascular Surgeons, London, July 1-3, P Senning, A. Fascia lata replacement of aortic valves. J. Thorac. Cardiovasc. Surg. 54:465, NOTICE FROM THE AMERICAN BOARD OF THORACIC SURGERY The American Board of Thoracic Surgery, with assistance from the National Board of Medical Examiners, is currently preparing an objective written examination and a restructured, objective oral examination to be given annually. The first examination will be held on September 29 and 30 and October 1, 1972, in San Francisco, California. (Although it had originally been planned to hold the entire fall examination in October, the examination has been rescheduled.) The written portion will consist of a 200-question multiple choice examination and, together with the oral examination, will determine the total grade given the candidate. The closing date for registration for the September, 1972, examination is June 1, The last semiannual examination, consisting of an oral clinical examination and an interpretive data examination (which combines roentgenogram interpretation, pathology, and interpretation of cardiac catheterization data) will be given in April, VOL. 13, NO. 2, FEBRUARY,