Kangaroo versus freestyle stentless bioprostheses in a juvenile sheep model: hemodynamic performance and calcification behavior

BACKGROUND: Glutaraldehyde-preserved bioprosthetic heart valve substitutes have limited performance and longevity due to tissue degeneration and calcification. The Freestyle valve (Medtronic Heart Valves, Inc, Minneapolis, MN) combines zero fixation pressure and proportional, variant-amino oleic acid (AOA) as antidegeneration and antimineralization measures. The aim of this study was to compare the calcification behavior of glutaraldehyde-preserved kangaroo aortic valves with Freestyle stentless bioprostheses in a juvenile sheep model. METHODS: Pulmonary artery and valve replacements were performed in juvenile sheep with Freestyle stentless aortic valves (n = 4) or glutaraldehyde-preserved kangaroo stentless aortic valves with no antimineralization measures (n = 6), and explanted at 200 postoperative days. RESULTS: Freestyle stentless valves and stentless kangaroo aortic valves showed normal valve function immediately postoperatively and up to 120 days. Valve leaflets of all valves were macroscopically free of visible calcification with normal histology. Valve leaflet calcification (microg Ca/mg tissue) was less in kangaroo than Freestyle (1.27 +/- 0.43 versus 2.38 +/- 1.37, p = 0.856). Aortic wall tissue calcification was severe in kangaroo and Freestyle (127.93 +/- 12.22 versus 122.19 +/- 11.99, p = 0.596). CONCLUSIONS: We conclude that glutaraldehyde-preserved kangaroo aortic valve leaflets are equal to AOA-treated Freestyle stentless valve leaflets with regard to calcification in juvenile sheep. Both bioprostheses are prone to aortic wall calcification. The low calcification features of the kangaroo aortic valve leaflets without antimineralization treatment may benefit the longevity of the valve.     

Sorin Solo stentless valve: extended adaptability for sinotubular junction mismatch

Stentless valve continence is affected by the implantation technique, annular symmetry and dilatation of the sinotubular junction. We tested in vitro how the Sorin Solo stentless pericardial valve adapts to a slightly dilated sinotubular junction. Stentless Sorin Solo aortic valves (25 mm) were sutured into a 32-mm Valsalva graft suspending the commissures into the expandable region of the graft. The neo-aortic root was pressurized and sinotubular junction size progressively decreased by wrapping the neocommissural ridge with Dacron rings. Direct endoscopic view and ultrasound imaging were used to observe geometry and morphology of leaflets, regurgitation, height and level of leaflets coaptation. Fresh porcine valves of the same annular size were used as controls. Solo valves had mild regurgitation at baseline, became continent at 32 mm sinotubular junction size and remained continent at any size of reduction, with optimal coaptation height and level. Porcine valves had severe regurgitation at baseline, became continent at 30 mm and showed mild insufficiency and reduction of the coaptation level at a sinotubular junction of 28 mm. The Solo valve prevents residual valve regurgitation for a wider range of sinotubular junction mismatch when compared with natural porcine valves. This extended tolerance to sinotubular junction mismatch suggests a safe use of stentless valves even in suboptimal geometry roots.     

The Sorin Freedom SOLO stentless aortic valve: easier implantation technique with potentially less risk of complications

Aortic valve replacement by bioprosthesis is increasingly being used. Among these, stentless bioprosthesis is becoming a valid choice due to its potential hemodynamic improvement. The Sorin Freedom SOLO stentless aortic valve (FS) (Sorin Biomedica Cardio, Saluggia, Italy) is widely used, with initial and midterm promising results. It is designed to be deployed in a straightforward manner in the supraannular position with a single running suture due to its reproducible implantation technique. Few specific valve-related complications, such as transient thrombocytopenia or rare thrombotic events, are known. Our experience, after the implantation of 33 Freedom SOLO, suggests that using the classical implantation technique, the noncoronary sinus adopts a conformation that increases the difficulty of the implant. Besides, it could also be distorted increasing the risk of periprosthetic leakage and hypothetically becoming the origin of thrombus. We present an easy and safe variation in the implantation technique of the FS that decreases the technical difficulty of the implantation, reduces the risk of periprosthetic leakage, and may additionally reduce the risk of thrombosis.     

First pulmonary valve replacement with Freedom Solo stentless valve in an adolescent. A case report

Tetralogy of Fallot (TOF) is a common form of cyanotic heart disease. Complete surgical correction in younger age group offers good long-term results with reasonable morbidity and improved prognosis in patients with TOF. However, following corrective surgery pulmonary valve replacement (PVR) might be required for residual pulmonary regurgitation in order to avoid irreversible right ventricular remodeling. Otherwise, residual uncorrected pulmonary regurgitation may lead to right ventricular dilatation, impaired biventricular function, ventricular arrhythmias and limited exercise capacity. We report the first case of Freedom Solo stentless valve (Sorin Group, Saluggia, Italy) implantation in the pulmonary position in an adolescent with severe pulmonary insufficiency 12 years after the repair of TOF. Pericardial stentless valves may be an alternative choice for pulmonary valve replacement to improve right ventricular contractile recovery and remodeling after PVR and may have impact on long-term survival.     

Recommendations for the implantation of the Pericarbon Freedom stentless valve

Based on our experience of 1000 subcoronary implants of the Sorin Pericarbon Freedom stentless valve, we give recommendations for the exact implantation technique. This article illustrates basic issues in the implantation technique with respect to continuous and interrupted suture to enable beginners and experienced surgeons to avoid some of the pitfalls. Additional remarks about sizing and early intraoperative echocardiographic findings complete this technical overview.     

Calcification characteristics of porcine stentless valves in juvenile sheep.

OBJECTIVE: To compare calcification characteristics of two porcine stentless valves (Toronto SPV and Freestyle) with different designs, fixation and antimineralization techniques using a juvenile sheep model of valve implantation inside the circulation. METHODS: The stentless valves (n = 2 x 6) were implanted in juvenile sheep in the pulmonary artery as an interposition, while the circulation was maintained with a right ventricular assist device. The model was validated by the implantation of, clinically well-known, porcine (Hancock II) and pericardial (Pericarbon) valves. Half of the valves were explanted after 3 months, the rest after 6 months. Valves were examined macroscopically, by X-ray, light microscopy (HE, Masson, Von Giesson, Von Kossa, PTAH stains), and transmission electron microscopy. Quantitative determination of the calcium content of the cusps was performed with atomic absorption spectrometry. RESULTS: After 3 months, the Freestyle had an extensively calcified aortic wall, most prominent at the outflow side of the porcine valve. After 6 months, calcification increased transmurally, but the valve cusps were free of calcification, and the inflow side was only slightly calcified. The Toronto SPV valve also started to calcify at the inflow side of the valve after 3 months with increased calcification after 6 months. The base of the Toronto SPV valve cusps showed slight calcification after 6 months of implantation. CONCLUSIONS: The pattern of calcification of the porcine aortic wall differs between the two studied stentless valves, with calcification located predominantly at the outflow side in the Freestyle valve, but also at the inflow side in the Toronto SPV valve. The cusps of the Freestyle valve were less prone to calcification than those from the Toronto SPV valve.     

Aortic Valve Replacement with Stentless Porcine Bioprostheses

The implantation of stentless porcine valves (SPVs) is technically more demanding than implantation of stented bioprosthetic valves. Implantation of the Toronto SPV bioprosthesis requires an,understanding of the relationships between the leaflets and the aortic annulus and sinotubular junction. In addition to proper alignment of the three commissures within the aortic root, the diameter of sinotubular junction should not exceed the external diameter of the porcine aortic valve after completion of the operation. The Medtronic Freestyle porcine aortic root bioprosthesis can be used for subcoronary implantation as well as for aortic root replacement. Degenerative calcification of a tricuspid aortic valve is the most common cause of aortic valve disease in older patients. Implantation of stentless valves in the subcoronary position is usually feasible because the geometry of the aortic root is well maintained in these patients. The bicuspid aortic valve is the second most common cause of aortic valve disease in older patients and the most common in younger patients. These patients frequently have dilated aortic root, and the Medtronic Freestyle bioprosthesis is ideal for implantation using the root inclusion technique. Stentless porcine bioprostheses are minimally obstructive and associated with low mean systolic gradients. In addition, they have better hemodynamic performance during exercise than stented bioprostheses. For these reasons, patient-prosthesis mismatch has not been described with stentless valves. Left ventricular function after aortic valve replacement appears to be better with stentless than with stented bioprostheses. Comparative, nonrandomized studies of aortic valve replacement with stented and stentless valves suggest that the risk of cardiac death is reduced with stentless valves and the rates of valve-related complications also appear to be lower. What remains unknown is whether stentless valves are more durable than stented ones.     

Aortic Valve Replacement with Stentless Porcine Bioprostheses

Aortic valve replacement with stentless porcine valve should provide superior hemodynamic results to stented porcine valve because the obstruction caused by the stent and the sewing ring is eliminated. In addition, the coronary sinuses of the recipient may allow for better dissipation of the mechanical stress to which the leaflets are subjected during diastole, thus enhancing durability of the heterograft. Aortic valve replacement with stentless glutaraldehyde-fixed aortic porcine bioprosthesis was carried out successfully in six young sheep. These animals were hemodynamically evaluated at 3 to 6 months after operation and found to have no resting gradients or any degree of aortic regurgitation. Explantation of the aortic heterograft revealed that it was well healed in the aortic root and had no evidence of any calcification. A clinical trial has been initiated and the results in the first five humans who underwent aortic valve replacement with a stentless porcine aortic bioprosthesis have been satisfactory.     

Thrombocytopenia after aortic valve replacement with the Freedom Solo stentless bioprosthesis

Stentless bioprostheses have been considered to achieve superior hemodynamics over stented bioprostheses for aortic valve replacement with improved long-term performance. We observed severe thrombocytopenia in patients who received the Sorin Freedom Solo aortic stentless pericardial bioprosthesis within the first days after implantation. Absolute and relative platelet counts within 2 weeks after implantation of either a stentless (Sorin Freedom Solo) or a stented (Sorin Mitroflow) bovine pericardial bioprosthesis were compared in a matched-pairs analysis in 40 patients. Except the preoperative values, absolute platelet count was higher at all time points in the Mitroflow group. In the Mitroflow group, the mean platelet count moderately dropped to a minimum of 60% of the initial value on POD 3 and fully recovered by POD 8. In the Freedom Solo group, platelet loss was significantly more severe (minimum relative value 25% on POD 4) with no recovery during follow-up (60% on POD 13). Eight patients of the Freedom Solo group experienced a critical platelet drop towards <20% of their initial values, in five of them absolute numbers decreased below 30,000/microl. No bleeding complications or other morbidity occurred. Attention should focus on the platelet count after implantation of the Freedom Solo bioprosthesis, especially in patients who are supposed to receive platelet inhibitors. However, the described phenomenon remains unexplained.     

Primary tissue failure of the freestyle stentless aortic root bioprosthesis

We present a case of early tissue failure of the Medtronic Freestyle stentless bioprosthesis used in the aortic position which led to reoperation 27 months after implantation. Almost one half of the left coronary cusp of the prosthetic valve had torn away along the annulus. The tear started from the left-non coronary commissure and reached the midpoint of the base of the left coronary cusp. The prosthetic valve was easily excised and replaced with a new mechanical valve. There was no sign of calcification or vegetation in the excised valve. The cause of the valve dysfunction was thought to be primary tissue failure. Long-term function of the Freestyle stentless valve should be carefully followed up.     

Primary tissue failure of the freestyle stentless aortic root bioprosthesis

We present a case of early tissue failure of the Medtronic Freestyle stentless bioprosthesis used in the aortic position which led to reoperation 27 months after implantation. Almost one half of the left coronary cusp of the prosthetic valve had torn away along the annulus. The tear started from the left-non coronary commissure and reached the midpoint of the base of the left coronary cusp. The prosthetic valve was easily excised and replaced with a new mechanical valve. There was no sign of calcification or vegetation in the excised valve. The cause of the valve dysfunction was thought to be primary tissue failure. Long-term function of the Freestyle stentless valve should be carefully followed up.     

Porcine stentless bioprostheses: prevention of aortic wall calcification by dye-mediated photo-oxidation

PURPOSE: Aortic wall calcification is problematic in stentless porcine valves. We evaluated the possible anticalcification effect of photo-oxidation on the aortic wall portion of porcine stentless bioprostheses. A comparison with glutaraldehyde-fixed tissue was made. METHODS: Six Photofix and six Freestyle valves were implanted in juvenile sheep in pulmonary position. Valves were explanted after 3 or 6 months and examined macroscopically, by x-ray, light, and transmission electron microscopy. Calcium content was determined by atomic absorption spectrometry. RESULTS: The aortic wall portion of all Photofix valves remained free from calcification, while the wall portion of glutaraldehyde-fixed valves calcified strongly, both after 3 and 6 months. Calcium content of the aortic wall portion was: 0.71 +/- 1.27 in the Photofix valves versus 10.78 +/- 77.22 in the Freestyle valves (P < 0.05). CONCLUSION: Photo-oxidation of a porcine stentless valve prevents calcification not only in the cusps but also in the aortic wall portion.     

Intravascular hemolysis in patients with new-generation prosthetic heart valves: a prospective study

OBJECTIVE: A prospective clinical study was designed to assess the frequency and severity of intravascular hemolysis in patients with new-generation, normally functioning prosthetic heart valves. METHODS: Hemolysis was evaluated in 172 patients with a mechanical prosthesis (53 CarboMedics and 119 Sorin Bicarbon) and in 106 patients with a bioprosthesis (15 St Jude Medical Toronto, 19 Baxter Perimount, and 72 Medtronic Mosaic) in the aortic position, mitral position, or both. Aortic valve replacement was performed in 206 patients, mitral valve replacement in 59 patients, and double valve replacement in 13 patients. The presence of hemolysis was assessed on the basis of the level of serum lactic dehydrogenase and serum haptoglobin and the presence and amount of reticulocytes and schistocytes in the peripheral blood. Severity of intravascular hemolysis was estimated on the basis of serum lactic dehydrogenase. Clinical, echocardiographic, and hematologic evaluations were performed 1, 6, and 12 months after discharge. RESULTS: None of the 278 patients experienced decompensated anemia, whereas at 12 months, mild subclinical hemolysis was identified in 49 patients, 44 (26%) with a mechanical prosthesis and 5 (5%) with a bioprosthesis (P <.001). At multivariate analysis, independent predictors of the presence of subclinical hemolysis were mitral valve replacement (P <.001), use of a mechanical prosthesis (P =.002), and double valve replacement (P =.02). Frequency of hemolysis in patients with stented aortic bioprostheses was 3%, whereas it was absent in those with stentless valves. Among mechanical valve recipients, double versus single valve replacement (P =.04) and mitral versus aortic valve replacement (P =.05) were correlated with the presence of hemolysis; double valve recipients also showed a more severe degree of hemolysis (P =.03). In patients with a Sorin Bicarbon prosthesis, hemolysis was less frequent (22% vs 34%, P =.09) and severe (P <.001) than in those with a CarboMedics prosthesis. CONCLUSIONS: In normally functioning prosthetic heart valves, subclinical hemolysis is a frequent finding. A low incidence of hemolysis is found in stented biologic prostheses, and it is absent in stentless aortic valves. Modifications of valve design may contribute to minimize the occurrence of hemolysis in mechanical prostheses.     

Calcification of tissue heart valve substitutes: progress toward understanding and prevention

Calcification plays a major role in the failure of bioprosthetic and other tissue heart valve substitutes. Tissue valve calcification is initiated primarily within residual cells that have been devitalized, usually by glutaraldehyde pretreatment. The mechanism involves reaction of calcium-containing extracellular fluid with membrane-associated phosphorus to yield calcium phosphate mineral deposits. Calcification is accelerated by young recipient age, valve factors such as glutaraldehyde fixation, and increased mechanical stress. Recent studies have suggested that pathologic calcification is regulated by inductive and inhibitory factors, similar to the physiologic mineralization of bone. The most promising preventive strategies have included binding of calcification inhibitors to glutaraldehyde fixed tissue, removal or modification of calcifiable components, modification of glutaraldehyde fixation, and use of tissue cross linking agents other than glutaraldehyde. This review summarizes current concepts in the pathophysiology of tissue valve calcification, including emerging concepts of endogenous regulation, progress toward prevention of calcification, and issues related to calcification of the aortic wall of stentless bioprosthetic valves.     

Modified stentless porcine valve enhances accelerated cuspal calcification in the juvenile sheep model

Objective: Stent mounting of any bioprosthesis, induces a loss of mobility and reduces the effective valve orifice. By contrast, for stentless procedures, the higher surgical technicality remains a major obstacle for many surgeons. In an attempt to facilitate the insertion of the stentless porcine aortic valve (Toronto SPV), we tried to alter the design by lowering the invasive profile at the depth of the sinuses on both coronary sites. This could theoretically facilitate the implant of the modified stentless valve with an easygoing single layer suture at the challenging subcoronary level and make it more attractive for every surgeon.Methods: Modifications of the standard model were done by lowering the profile at the depth of the sinuses on both coronary sites, whether by plication or excision of the protruding porcine aortic wall at the nadir of each coronary sinus. Nine juvenile sheep underwent implantation of stentless porcine aortic valves in pulmonary position: 3 standard Toronto SPV, 3 plicated Toronto SPV and 3 excised Toronto SPV. In each series, valves were explanted after 3 months. Valves were analyzed.Results: The cusps of standard Toronto SPV were perfectly functioning and pliable, without visible calcification after three months. The calcium content of the cusps was less than those in the plicated and excised Toronto SPV (2.4±0.7 μg/mg versus 10.8±5.9 and 6.7±3.4 μg/mg). In the plicated and excised valves, calcification of the cusp was more pronounced in the commissural region (3.9±1.9, 29.0±16.7, 13.8±9.5 μg/mg in the standard, plicated and excised Toronto SPV, respectively). On the other hand, the aortic wall from the plicated Toronto SPV had more calcium than that from the other groups (53.6±6.3, 41.2±7.1, 45.2±7.4 μg/mg in the plicated, standard and excised Toronto SPV, respectively).Conclusions: The modification of stentless porcine valve enhanced accelerated cuspal calcification in the commissural region. It accentuated that the correct implantation technique for stentless procedures is extremely important in order to prevent early degeneration.     

Use of stentless xenografts in the aortic position: determinants of early and late outcome

BACKGROUND: Whether to perform a stentless aortic valve replacement (AVR) is not well established. Our aim was to determine the outcome after AVR with stentless xenograft valves. METHODS: Between 1996 and 2001, a total of 404 patients (mean age 70.4 years) underwent a stentless AVR by one surgeon in our unit. Concomitant procedures were performed in 132 patients (33%). Twenty patients (6.4%) had undergone previous AVR. Eleven types of stentless xenograft valves were implanted: Medtronic Freestyle in 221 patients (55%), Shelhigh in 55 (14%), Shelhigh composite conduit in 33 (8%), Sorin in 26 (6%), Cryolife O'Brien in 25 (6%), Aortech-Elan in 17 (4%), Edwards Prima in 14 (4%), Toronto SPV in 7 (2%), and other valves in 6 (1%). A subcoronary implantation technique was used in 302 cases (76%), complete root replacement in 62 (15%), and a modified Bentall-De Bono procedure in 33 (8%). Mean follow-up was 19.4 months (range, 1.2 to 60.6 months). RESULTS: Overall hospital mortality was 4.2%. This was 2.4% for isolated AVR, 3.6% for AVR and coronary artery bypass grafting, 5.5% for replacement of two or more valves, and 12% for the modified Bentall procedure. On multiple logistic regression redo cardiac operation (p = 0.0006), cardiogenic shock (p = 0.001), left ventricular ejection fraction less than 0.30 (p = 0.01), modified Bentall procedure (p = 0.03), and endocarditis (p = 0.04) were predictors of in-hospital death. Five-year freedom from thromboembolism, hemorrhage, prosthetic endocarditis, structural valve deterioration, and reoperation was 97%, 99%, 99%, 98%, and 96%, respectively. Kaplan-Meier survival at 5 years was 88%. On Cox regression, cardiogenic shock (p = 0.001) and older age (p = 0.03) were adverse predictors of survival. At echocardiographic examination within 6 months from the operation, mean aortic valve gradients were 15 +/- 6 mm Hg, 12.8 +/- 3 mm Hg, 10.8 +/- 4 mm Hg, 9.3 +/- 3 mm Hg, 9.1 +/- 4 mm Hg, and 8.2 +/- 3 mm Hg for valve sizes of 19, 21, 23, 25, 27, and 29 mm, respectively. CONCLUSIONS: The availability of several stentless valve designs facilitates the surgical treatment of diverse aortic valve or root diseases with encouraging early and mid-term results. Patients requiring concomitant procedures may also benefit from the excellent hemodynamic characteristics of a stentless valve. We consider stentless AVR the treatment of choice for patients older than 60 years and those having small aortic roots.     

Stentless bioprostheses in aortic root disease

INTRODUCTION: The availability of aortic homografts is steadily decreasing. In the meantime, stentless xenografts convey similar flow characteristics, and tissue preservation methods are improving durability. Initially, these valves were contraindicated in aortic roots with discrepancy between annulus and sinotubular junction or with extensive calcification or sepsis. With increasing experience stentless xenografts are now applied in a wide spectrum of aortic root disease. METHODS: I reviewed our own experience with stentless aortic bioprosthesis for aortic valve replacement (AVR) and more taxing root problems. I used these valves in aortic aneurysm repair, acute Type A dissection, and for endocarditis with abcess formation. I studied valve hemodynamics, regression of left ventricular hypertrophy, and comparative survival with stented bioprostheses. RESULTS: Stentless bioprostheses convey hemodynamic and possibly survival benefit through a low incidence of valve-related complications. They provide a useful alternative to aortic homografts in endocarditis, Type A dissection, and aortic aneurysm surgery. CONCLUSIONS: Stentless bioprostheses are no longer confined to AVR alone. Experience supports the use of stentless bioprostheses where aortic homografts were previously applied. With availability in a wide range of sizes.     

Raised Endothelin Content in Bronchoalveolar Lavage Fluid During Lung Allograft Rejection in Pigs

Abstract

Objectives. Freedom Solo is a stentless biological aortic valve which is implanted supra-annularly with a single suture line. An increased risk of postoperative thrombocytopenia in the early postoperative period has been reported in recent studies. In our study we evaluated postoperative haemodynamic performance and thrombocyte-levels. Design. Thirty seven patients who underwent valve implantation of the Sorin Freedom Solo stentless valve were included. The haemodynamic performance of the valve was evaluated by transthoracic echocardiography postoperatively at the fourth day (mean) and after a median of 4.2 months. Results. The mean gradient (mmHg) of Freedom Solo was 7.5 at four days and 8.6 at 4.2 months. Postoperatively no patient had more than grade 1 leakage. Seven percent of the patients had a reduction of thrombocytes to less than 20% of the preoperative level. Seventy six percent had a minimum postoperative thrombocyte level less than 100*10⁹/L. The 30 days mortality in our patient material was zero. Conclusions. Implantation of the Freedom Solo valve was uncomplicated in our experience. Favourable transvalvular gradients and no significant leaks were found. In accordance with the literature, we found a high percentage of patients having a postoperative level of thrombocytes less than 100*10⁹/L after implantation of Freedom Solo.     

Aortic valve translocation for treatment of a deteriorated stentless valve

A 54-year-old woman was admitted to our hospital with recurrent chest pain for 1 month. She had a history of aortic root replacement with a stentless valve following aortic valve replacements done twice 12 years ago, and coronary artery bypass grafting 6 years ago. The stentless valve was implanted with the full-root technique. After admission, she was diagnosed with a saphenous vein graft aneurysm in the proximal anastomotic site and severe aortic regurgitation due to stentless valve deterioration. These lesions were successfully treated using aortic valve translocation. The advantage of this procedure is that it avoids dissection and removal of the stentless valve implanted using the full-root technique. Aortic valve translocation can be one of useful alternatives for stentless valve reoperation.     

Mitral and mitro-aortic valve replacement with Sorin Bicarbon valves compared with St. Jude Medical valves

OBJECTIVE: We assessed the clinical results of two bileaflet mechanical valves: the St. Jude Medical (SJM) and the Sorin Bicarbon (Sorin Bicarbon) used either in single mitral valve replacement (MVR) or in double, aortic and mitral, valve replacement (DVR). METHODS: Between September 1990 and November 1995, 217 patients received either a St. Jude Medical (n=134) or a Sorin Bicarbon (n=86): 136 mitral valve replacement with 83 St. Jude Medical and 53 Sorin Bicarbon and 84 double valve replacement with 51 St. Jude Medical and 33 Sorin Bicarbon. There was no difference between both St. Jude Medical and Sorin Bicarbon cohorts in respect of mitral valve physiopathology, etiology of valve disease, associated lesions, echocardiographic and hemodynamic data. The only significant preoperative difference was the age of patients within the double valve replacement group and the size of implanted valves within the mitral valve replacement group. Follow-up was 100% complete with a mean of 39+/-18 months, ranging between 6 and 68 months. The total follow-up was 657 patient-years (pt-y): 396 pt-y in the mitral valve replacement group and 274 pt-y in the double valve replacement group. RESULTS: Hospital mortality (St. Jude Medical: 2.2%; Sorin Bicarbon: 6.9%) and late mortality (St. Jude Medical: 8.4%; Sorin Bicarbon: 6.3%) were not significantly different. Ten deaths were considered valve-related (St. Jude Medical 6, Sorin Bicarbon 4). The estimated 4-yr overall survival, including hospital mortality, was for St. Jude Medical--mitral valve replacement: 89+/-4% and St. Jude Medical--double valve replacement: 93+/-4%, and for Sorin Bicarbon--mitral valve replacement: 87+/-5% and Sorin Bicarbon--double valve replacement: 91+/-5%. The linearized incidence (% per pt-y) of valve-related complications was 6.39 in the St. Jude Medical cohort and 9.2 in the Sorin Bicarbon cohort. The linearized incidence (% pt-y) of the prevalent complication, valve thromboembolism and bleeding, was for St. Jude Medical-mitral valve replacement: 3.41, St. Jude Medical--double valve replacement: 3.16 and for Sorin Bicarbon--mitral valve replacement: 2.17 and Sorin Bicarbon--double valve replacement: 3.67. The differences between each group of an estimated 4-yr freedom from combined thromboembolism and bleeding were not significant (St. Jude Medical--mitral valve replacement: 90+/-4%, St. Jude Medical--double valve replacement: 84+/-6%, and for Sorin Bicarbon--mitral valve replacement: 94+/-3% and Sorin Bicarbon--double valve replacement: 75+/-17%). CONCLUSIONS: In this clinical non-randomized study, there was no evidence of any significant difference between St. Jude Medical and Sorin Bicarbon valves over a 4-yr follow-up.