The diameter of the aortic valve is in direct proportion

Transcription

1 The CarboMedics Top-Hat Supraannular Prosthesis José M. Bernal, MD, Rafael Martin-Duran, MD, José M. Rabasa, MD, and José M. Revuelta, MD Departments of Cardiovascular Surgery and Echocardiography, Hospital Universitario Valdecilla, Universidad de Cantabria, Santander, Spain Background. The CarboMedics Top-Hat supraannular prosthesis was designed to permit the implantation of a larger prosthesis. Methods. Between June 1993 and November 1996, 127 patients (average age, years) received a CarboMedics Top-Hat supraannular aortic prosthesis. The average follow-up was 15.7 months, and all surviving patients underwent echocardiographic study. This group is compared with 656 patients in whom a standard CarboMedics prosthesis was implanted and also with 2,927 patients who received other aortic prostheses. Results. Using the standard and the supraannular sizers, there was an average increase of one size in favor of the supraannular prosthesis: mm standard versus mm supraannular (p < 0.005). For each prosthesis size (19 to 23 mm), the body surface area of the patients in whom a CarboMedics supraannular prosthesis was implanted was significantly smaller than that in those who received a CarboMedics standard prosthesis or any other model. Hospital mortality was 3.9%, and late mortality was 5.5%. The actuarial survival was 86.5% 3.9% at 42 months. Conclusions. Using the CarboMedics supraannular prosthesis allows implantation of a larger prosthesis compared with the standard CarboMedics prosthesis or other models. This advantage is especially important in patients with a small aortic root. (Ann Thorac Surg 1999;67: ) 1999 by The Society of Thoracic Surgeons The diameter of the aortic valve is in direct proportion to the body surface area (BSA) of the patient. In general, BSA values lower than 1.7 m 2 are highly predictive of a small aortic root and thus indicate the need of a 19-mm prosthesis [1, 2]. In a Doppler echocardiographic study, González-Juanatey and colleagues [3] showed that various 19-mm prostheses of the latest generation result in substantial obstruction of the left ventricular outflow tract and less marked reduction in hypertrophy of the left ventricle compared with larger prostheses. Thus, the solutions to the problem of a small aortic root are to design a small prosthesis with better hemodynamics, to implant a larger prosthesis by aortic root enlargement, or to modify the sewing cuffs to take advantage of supraannular implantation. The CarboMedics Top-Hat supraannular prosthesis (introduced in 1993) is a standard valve in which the cuff has been transferred to the inflow level of the valve. As a result, the prosthesis sits above the annulus rather than within it. The valve housing protrudes into the aortic root like a top hat. Here we describe our clinical and echocardiographic experience with this aortic prosthesis. Accepted for publication Nov 3, Address reprint requests to Dr Bernal, Cirugía Cardiovascular, Hospital Universitario Valdecilla, Santander, Spain. Material and Methods In 1993, a prospective study was started to evaluate the Top-Hat prosthesis. Between June 1993 and November 1996, 127 patients underwent aortic valve replacement with the supraannular prosthesis. Of these 127 patients, 68 (53.5%) were women and 59 (46.5%) men. The average age was years (range, 28 to 81 years). In the preoperative period, 26 patients (20.5%) were in New York Heart Association class II, 79 (62.2%) were in class III, and 22 (17.3%) were in class IV. Primary valve replacement was performed on 92 patients (72.4%) and repeat valve replacement, on 35 patients (27.6%), 28 of whom had a previous aortic prosthesis in place. Seventysix patients (59.8%) were in sinus rhythm, 50 (39.4%) were in atrial fibrillation, and 1 had a pacemaker (0.8%). Hemodynamic and coronary angiographic examinations were done on 88 patients (69.3%). The remaining 39 patients (30.7%) were diagnosed by echocardiography exclusively. The left ventricular ejection fraction calculated by ventriculography ranged between 0.15 and 0.78 (average ejection fraction, ). On the basis of echocardiography, left ventricular function was considered normal in 29 patients and depressed in 10. Isolated aortic valvulopathy was diagnosed in 83 patients (65.4%), mitral and aortic valvulopathy in 40 patients (31.5%), and mitral, aortic, and tricuspid valvulopathy in 4 patients (3.1%). The aortic lesion was pure stenosis or a double lesion with preponderance of stenosis in 106 patients (83.5%) and insufficiency in 21 patients (16.5%). The cause 1999 by The Society of Thoracic Surgeons /99/$20.00 Published by Elsevier Science Inc PII S (99)

2 1300 BERNAL ET AL Ann Thorac Surg CARBOMEDICS SUPRAANNULAR VALVE 1999;67: of the valvular disease was degenerative or calcific in 63 patients (49.6%), rheumatic in 33 patients (26%), and active infectious endocarditis in 3 patients (2.4%); of the 28 patients (22%) with a previously placed prosthesis, 25 had structural deterioration of the bioprosthesis, and 1 each had valvular thrombosis, valvular dehiscence, and elective bioprosthesis explantation. Thirteen patients (10.2%) had concomitant coronary artery disease. Surgical Technique and Valve Measurement The operation was performed with standard cardiopulmonary bypass and moderate hypothermia (28 to 30 C). Myocardial protection was achieved with intermittent blood cardioplegia, antegrade initially and retrograde as of January After aortic valve resection and decalcification of the valve root when necessary, both the standard sizer and the supraannular sizer were used in each patient. The aortic prosthesis was implanted in the supraannular position. Pledgets were placed in the ventricular surface of the native aortic ring and knots, in the aortic aspect of the prosthetic sewing cuff. In patients with low-lying coronary ostia or a narrow sinotubular junction, stitches were arranged in an imaginary plane at the level of the most distal point of the annulus of each aortic leaflet. Forty 19-mm prostheses (31.5%) were implanted, mm prostheses (45.7%), and mm prostheses (22.8%). Forty-four patients had assoociated mitral valve procedures: mitral valve replacement with the Carbo- Medics standard prosthesis in 40 and mitral valve repair in 4. Four patients underwent associated tricuspid valve procedures: replacement with a Hancock II bioprosthesis in 1 and repair in 3. Associated myocardial revascularization with an average of 1.5 grafts per patient was performed in 13 patients. The surviving patients were maintained on a regimen of Coumadin (crystalline warfarin sodium), with a recommended international normalized ratio ranging between 2.5 and 3.5. The ratio was modified according to the individual requirements of each patient during follow-up. Doppler echocardiographic study was performed after discharge between postoperative months 1 and 42. In 91.3% of the survivors, this study was carried out 3 months or more after operation. All examinations were done with the patient in the left lateral decubitus position with simultaneous electrocardiographic recording. A commercially available echocardiograph with continuous wave (cw), pulsed wave (pw), and color Doppler capabilities (Vingmed 750) was used. All measurements were done on-line and recorded on VHS videotape for off-line analysis if necessary. Peak and mean gradients were calculated using the modified Bernoulli equation [4]: pressure gradient (P) 4(V 2 2 V 1 1)(V 2 2, distal velocity; V 1 1, proximal velocity). Because of the usually narrow left ventricular outflow tract in these patients, special care was taken not to neglect V 1. Effective orifice area was obtained with the continuity equation: A 2 A 1 V 1 /V 2 (A 2, orifice effective area of the prosthesis, A 1, left ventricle outflow tract area) [5 7]. Three consecutive beats in sinus rhythm and eight in atrial fibrillation were analyzed. At the conclusion of follow-up, 90 (78.3%) of the 115 patients alive were studied at our center by the same observer, and 25 patients (21.7%) were followed in other hospitals by the referring cardiologists. Follow-up of the survivors was completed between October and December Follow-up ranged from 30 days to 42 months with an average time of 15.7 months and an accumulated follow-up of 175 patient-years. Follow-up was 100% complete. Statistical Analysis The Patient Analysis and Tracking System database, Version (Dendrite Clinical Systems, Inc, Portland, OR) was used. Values are shown as the mean the standard deviation. The Student t test was used for the comparison of quantitative variables. Actuarial curves were produced by the Cox actuarial method. The implanted prosthesis size study was done by comparing measurements obtained with the CarboMedics standard and Top-Hat sizers. Results Mortality and Morbidity Five patients (3.9%) died in the hospital, and 7 patients (5.5%) died late. The causes of the five hospital deaths were low cardiac output (n 3), sepsis (n 1), and pulmonary thromboembolism (n 1). Of the late deaths, five were due to cardiac-related causes: unknown (n 2), thromboembolism (n 1), cardiac insufficiency resulting from dehiscence of a mitral valve prosthesis (n 1), and prosthetic valve endocarditis treated medically, (n 1). Two of the late deaths had noncardiac causes: cancer of the colon (n 1) and cancer of the pancreas (n 1). The overall actuarial survival was 86.5% 3.9% at 42 months (Fig 1). Excluding deaths from noncardiac causes, the actuarial survival was 88.9% 3.9% at 42 months of follow-up. Fig 1. Actuarial survival curve at 42 months after operation.

3 Ann Thorac Surg BERNAL ET AL 1999;67: CARBOMEDICS SUPRAANNULAR VALVE 1301 Table 1. Body Surface Area of Patients Given CarboMedics Top-Hat Supraannular, CarboMedics Standard, or Other Type of Prosthesis in 19- to 23-mm Sizes a Type of Prosthesis 19 mm 21 mm 23 mm Top-Hat (n 127) b b b Standard (n 656) Other (n 2,927) a Data are shown in square meters and as the mean the standard deviation. b Significance: p 0.001, Top-Hat versus Standard and Top-Hat versus Other. Fig 2. Comparison between measurements obtained using Carbo- Medics standard and supraannular ( Top-Hat ) aortic valve sizers. Two patients required a repeat operation: 1 for dehiscence of a mitral valve prosthesis and 1 because of mitral and tricuspid valve disease. One patient had early prosthetic aortic valve endocarditis and died without a repeat operation. Three central (neurologic event) thromboembolic episodes were recorded: one resulted in death, and two were without sequelae. Two patients sustained major anticoagulant-related hemorrhages and 11 patients, minor hemorrhages. Of the 115 patients alive at the conclusion of follow-up, 96 (83.5%) were in New York Heart Association functional class I, 16 (13.9%) were in class II, and 3 (2.6%) were in class III. Comparison of Valve Measurements Figure 2 shows the comparison between the measurements obtained using the CarboMedics standard and Top-Hat supraannular prosthesis sizers. The average of values obtained with the standard sizers was mm and that obtained with the supraannular sizers, mm ( p 0.005). Of all 3,710 aortic valve replacements performed in our institution, 406 were reoperations involving a previous 19- to 23-mm aortic prosthesis of any type; the size of the prosthesis implanted and that of the prosthesis explanted were measured. The average size of the Top-Hat prosthesis implanted in the 28 patients with a previous aortic valve replacement was mm, and the average size of the prosthesis explanted was mm ( p not significant). Among the 656 patients in whom a Carbo- Medics standard prosthesis was implanted, 102 had had a previous aortic valve replacement. The average size of the implanted prosthesis was mm, and the average size of the explanted prosthesis was mm ( p 0.001). Of the 2,927 patients in whom an aortic prosthesis other than the CarboMedics standard or the Top-Hat was implanted, 276 had undergone aortic valve replacement previously. The average implanted prosthesis size was mm, and the average size of the explanted prosthesis was mm ( p 0.001). The comparison between the average BSAs of patients receiving the three different sizes of Top-Hat prostheses (19, 21, and 23 mm) versus patients given a Carbo- Medics standard prosthesis or another type of prosthesis in the same sizes is shown in Table 1. For all valve sizes, the BSA was significantly smaller ( p 0.001) with the Top-Hat prosthesis. Doppler Echocardiographic Assessment Postoperative values obtained at echocardiographic assessment of each patient did not show significant differences in function. Ninety patients (78.3%) were seen in our center and 25 patients (21.7%) in other hospitals. Table 2 shows the Doppler echocardiographic values obtained for each size of Top-Hat prosthesis, 19, 21, and 23 mm. Of the patients studied, 40.8% were in atrial fibrillation. Comment The problem of the small aortic root has been addressed in various ways. The techniques to enlarge the aortic root permit the implantation of a larger-sized prosthesis than the size of the native aortic root. However, they are not free from added risk [7] and considerably lengthen the time of myocardial ischemia. Aortic homografts are appropriate for the small aortic root, as their hemodynamic behavior is excellent, but their durability as well as their availability is limited. The use of porcine stentless bioprostheses is a newer alternative for dealing with the small aortic root [8, 9]. However, the durability of these Table 2. Results of Doppler Echocardiography for CarboMedics Top-Hat Supraannular Prosthesis in 19- to 23-mm Sizes a Variable 19 mm (n 40) 21 mm (n 58) 23 mm (n 29) Peak gradient (mm Hg) Mean gradient (mm Hg) Effective orifice area (cm 2 ) a Data are shown as the mean the standard deviation.

4 1302 BERNAL ET AL Ann Thorac Surg CARBOMEDICS SUPRAANNULAR VALVE 1999;67: prostheses is not yet known, and indications do not include the total population needing aortic valve replacement. Bioprostheses and mechanical prostheses of the latest generation have not solved the problem of the small aortic root [3]. At present, patients in whom a 19-mm prosthesis is implanted can be considered to have a poorer prognosis because of the persistence of high transvalvular gradients and the inability to substantially reduce left ventricular hypertrophy [10, 11]. Another newer option is to modify the sewing cuff so as to create a supraannular prosthesis. This allows the use of a larger size than would be possible for a prosthesis implanted in the intraannular position. Initial experience with these sewing cuff modifications has been published [12 15]. One study analyzes the clinical and echocardiographic results in the largest published series to date with the Top-Hat prosthesis. Analysis of the possible advantages of using prostheses designed specifically for supraannular implantation is complex. In our opinion, the use of sizers to determine prosthesis to implant is subjective. Forcing the use of a prosthesis a size larger than the correct size can cause serious complications, such as obstruction of the coronary ostia or dehiscence around the prosthesis, which are more frequent in cases of severely calcified aortic roots. The surgical technique of implantation of the CarboMedics supraannular valve is crucial to prevent complications such as ostial obstruction of coronary arteries or paraprosthetic leak. In our experience since 1974, the problem of the small aortic root has been very evident in our patient population. Of the 3,710 aortic valve replacements performed, 27.3% of the patients had a BSA smaller than 1.60 m 2, which correlates directly with the 28.1% implantation rate of 19- and 21-mm prostheses. Of this 28.1%, 7.4% were 19 mm and 20.7%, 21 mm. The comparison between the measurements taken with the CarboMedics standard and Top-Hat prosthesis sizers showed a significant difference of one size in favor of the Top-Hat. Although this outcome agrees with that of Roedler and coauthors [15], some subjectivity may be involved. On the other hand, when an aortic prosthesis (mechanical or biological) is explanted, the native aortic root is severely fibrosed and rigid, and it frequently becomes necessary to implant a smaller-sized prosthesis. This was clear in our experience when the average size of the prosthesis implanted and that of the one explanted were measured. For the CarboMedics standard prosthesis or other prostheses, an average of one size is lost: mm and mm, respectively, for prostheses implanted and mm and mm, respectively, for those explanted ( p 0.001). In contrast, in this series, aortic valve prostheses averaging mm in size were explanted from 28 patients, and a Top-Hat prostheses of the same size, mm, were implanted ( p not significant). The similarity in sizes demonstrates the advantage of the supraannular implant. The comparison of the average BSAs shows that patients with a Top-Hat prosthesis had a significantly smaller BSA for each of the three sizes (19, 21, and 23 mm) than that of patients for whom a CarboMedics standard prosthesis or other type of valve substitute was used. In practice, this means that BSAs being equal, a larger Top-Hat prosthesis can be used. These analyses must be looked at carefully because of the characteristics of the groups studied, although they do suggest that the use of a prosthesis designed specifically for supraannular implantation constitutes an especially interesting advantage in patients with small aortic roots. The Doppler echocardiographic study was performed in most survivors (91.3%) 3 months or more after operation (range, 3 to 42 months). The data obtained do not differ significantly from those published by other groups [16, 17] for the CarboMedics standard prosthesis. As the mechanical part of the Top-Hat prosthesis has not been modified from the CarboMedics standard prosthesis, this finding is reasonable. The difference between the two prostheses does not affect the valve areas for each size, but it does allow the opportunity to implant a larger size in each patient. Because of the number of patients and the length of follow-up, analysis of the clinical results in terms of mortality and morbidity contributes limited information. As the modification of the Top-Hat prosthesis alters only the sewing cuff, the clinical results should not vary in regard to those published for the CarboMedics standard prosthesis [18, 19]. In our experience, modification of the sewing cuff has not produced any incidence of paravalvular leak. We conclude that in our experience, the CarboMedics supraannular Top-Hat prosthesis allows the implantation of a larger-sized prosthesis than would otherwise be possible. This option is especially valuable for patients with a small aortic root. References 1. Chambers J. Echocardiography and the small aortic root. J Heart Valve Dis 1996;5(Suppl 3): Franzen SF, Huljebrant IE, Konstantinov IE, Nylander E, Olin CL. Aortic valve replacement for aortic stenosis in patients with small aortic root. J Heart Valve Dis 1996;5 (Suppl 3): González-Juanatey JR, Garcia-Acuña JM, Vega M, et al. Influence of size of aortic valve prostheses on hemodynamics and change in left ventricular mass: implications for the surgical management of aortic stenosis. J Thorac Cardiovasc Surg 1996;112: Rijsterborgh H, Roelendt J. Doppler assessment of aortic stenosis: Bernoulli revisited. Ultrasound Med Biol 1987;13: Otto CM, Pearlman AS, Comess KA, Reamer RP, Janko CL, Hunsman LL. Determination of stenotic aortic valve area in adults using Doppler echocardiography. J Am Coll Cardiol 1986;7: Oh JK, Taliercio CP, Holmes DR, et al. Prediction of the severity of aortic stenosis by Doppler aortic valve area determination: prospective Doppler-catheterization correlation in 100 patients. J Am Coll Cardiol 1988;11: Abdelnoor M, Hall KV, Nitter-Hauge S, Linberg H, Ovrum E. Prognostic factors in aortic valve replacement associated with narrowing aortic roots. Scand J Thorac Cardiovasc Surg 1986;20:

5 Ann Thorac Surg BERNAL ET AL 1999;67: CARBOMEDICS SUPRAANNULAR VALVE Walther T, Falk V, Diegeler A, et al. Stentless bioprostheses for small aortic root. J Heart Valve Dis 1996;5(Suppl 3): Sintek CF, Fletcher AD, Khonsari S. Small aortic root in the elderly: use of stentless bioprosthesis. J Heart Valve Dis 1996;5(Suppl 3): Kratz JM, Sade RM, Crawford FA Jr, Crumbley AJ III, Stroud MR. The risk of small St. Jude aortic valve prostheses. Ann Thorac Surg 1994;57: Sim EKW, Orszulak TA, Schaff HV, Shub C. Influence of prosthesis size on change in left ventricular mass following aortic valve replacement. Eur J Cardio-thorac Surg 1994;8: De Paulis R, Sommariva L, Russo F, et al. Doppler echocardiography evaluation of the CarboMedics valve in patients with small aortic anulus and valve prosthesis body surface area mismatch. J Thorac Cardiovasc Surg 1994;108: De Brux JL, Subayi JB, Binuani P, Laporte J. Dopplerechocardiographic assessment of the CarboMedics supraannular Top-Hat prosthetic heart valve in the aortic position. J Heart Valve Dis 1996;5(Suppl 3):S De Paulis R, Sommariva L, De Matteis GM, et al. Hemodynamic performances of small diameter CarboMedics and St. Jude valves. J Heart Valve Dis 1996;5(Suppl 3):S Roedler S, Moritz A, Wutte M, Hoda R, Wolner E. The CarboMedics top hat supraannular prosthesis in the small aortic root. J Cardiac Surg 1995;10: Chambers J, Cross J, Deverall P, Sowton E. Echocardiographic description of the CarboMedics bileaflet prosthetic heart valve. J Am Coll Cardiol 1993;21: Ihlen H, Molstad P, Simonsen S, et al. Hemodynamic evaluation of the CarboMedics prosthetic heart valve in the aortic position: comparison of noninvasive and invasive techniques. Am Heart J 1992;123: Copeland JG III, Sethi GK, North American team of clinical investigators for the CarboMedics prosthetic heart valve. Four-year experience with the CarboMedics valve: the North American experience. Ann Thorac Surg 1994;58: Bernal JM, Rabasa JM, Gutierrez-Garcia F, Morales C, Nistal JF, Revuelta JM. The CarboMedics valve: experience with 1,049 implants. Ann Thorac Surg 1998;65: The Annals of Thoracic Surgery Cumulative Index The Annals of Thoracic Surgery 31-year cumulative index, volume 1 through volume 60, January 1965 through December 1995, is available in two versions: in print (ISBN ) and on CD-ROM (ISBN ). Both print and CD-ROM versions contain subject and author indexes for the 31 years of the journal to date. The CD-ROM also contains all of the journal s published scientific abstracts; hypertext links between article titles, subject headings, authors, and abstracts; a search function that allows full-text, Boolean, and keyword searches; and functions to select and format references for future use. The CD-ROM is both DOS/ Windows and Macintosh compatible. The price is $95.00 for the CD-ROM version, $95.00 for the print version, or only $ for both the CD-ROM and print versions. Contact Elsevier Science Inc to place your order. Telephone (212) ; Fax (212) by The Society of Thoracic Surgeons Ann Thorac Surg 1999;67: /99/$20.00 Published by Elsevier Science Inc