Comparative analysis of mechanical and bioprosthetic valves after aortic valve replacement

Comparative long-term performance characteristics of Bj?rk-Shiley mechanical and bioprosthetic valves were analyzed for patients undergoing aortic valve replacement between 1976 and 1981. A total of 419 patients received either a standard Bj?rk-Shiley (n = 266) or bioprosthetic (porcine, n = 126, or pericardial, n = 27) aortic valve. Cumulative patient follow-up was 1,705 patient-years; the average patient follow-up was 4.1 +/- 2.7 years. Survival data were obtained for all but 11 patients (97% complete follow-up) up to 9 years after operation. Survival at 5 years was 81% +/- 4% (+/- standard error) for Bj?rk-Shiley and for bioprosthetic valve recipients. Valve failure in the Bj?rk-Shiley group was predominantly due to valve-related mortality and did not result from structural failure. Patients with bioprosthetic valves experienced valve failure as a result of prosthetic valve endocarditis and intrinsic valve degeneration. Although patients with bioprostheses experienced a lower incidence of valve-related morbidity than Bj?rk-Shiley valve recipients (p less than 0.03), no difference could be demonstrated in the incidence of valve-related mortality or valve failure at 5 years between bioprosthetic and Bj?rk-Shiley valves. Mortality rate from valve failure was higher for Bj?rk-Shiley (86%, 12/14) than bioprosthetic valves (36%, 5/14) (p less than 0.01).     

Long-term comparative analysis of the Bj?rk-Shiley and Hancock valves implanted in 1975

The long-term results in all patients undergoing isolated mitral, aortic, or double mitral-aortic heart valve replacement operated upon in 1975 has been retrospectively analyzed. A total of 153 patients received the standard Bj?rk-Shiley (flat pyrolytic disc) mechanical prostheses and 150 patients received the noncomposite Hancock porcine xenograft. Overall operative mortality was not significantly different between groups. All patients receiving a Bj?rk-Shiley prosthesis, but none in the Hancock group, received long-term anticoagulant therapy. Medium and long-term actuarial survival rates (5 and 10 years postoperatively) were comparable for the two groups (88% for Bj?rk-Shiley and 84% for Hancock [NS] at 5 years; 86% for Bj?rk-Shiley and 80% for Hancock at 10 years [NS]). The incidence of systemic embolism was similar in the two groups (1.6% +/- 0.4% per patient-year for the Bj?rk-Shiley group and 1.3% +/- 0.3% per patient-year for the Hancock group [NS]). Also the incidence of endocarditis was similar (0.6% +/- 0.2% per patient-year for the Bj?rk-Shiley group and 0.8% +/- 0.3% per patient-year for the Hancock group [NS]). In the Hancock group the overall incidence of reoperations was significantly higher than in the Bj?rk-Shiley group (4.2% +/- 0.6% per patient-year versus 0.9% +/- 0.3% per patient-year (p = 0.001). The major cause for reoperation in the Hancock group was primary tissue failure (3% +/- 0.5% per patient-year). In the Bj?rk-Shiley group the major cause of reoperation was valve thrombosis (0.5% +/- 0.2% per patient-year). Therefore, accepting the fact that other bioprostheses may behave differently from the Hancock noncomposite xenograft, we currently restrict our indications for valve replacement with bioprostheses.     

Optimal insertion technique for the Bj?rk-Shiley valve in the narrow aortic ostium

The Bj?rk-Shiley tilting disc valve was used for aortic valve replacement (AVR) in 250 consecutive patients between 1977 and 1982. One hundred and ninety-six patients had isolated AVR, and 54 had combined procedures (double- or triple-valve replacement in 31, associated coronary artery bypass grafting in 20, and miscellaneous procedures in 3). A special technique for inserting large Bj?rk-Shiley valves without using outflow patches or annuloplastic procedures was developed. This method included allowing the right portion of the aortic incision to end about 0.5 cm above the noncoronary sinus; the use of simple interrupted sutures; placement of the prosthetic sewing ring on top of the annulus of the noncoronary sinus, thereby tilting the valve slightly in the outflow tract; and routine orientation of the major opening of the valve toward the annulus of the noncoronary sinus. This orientation resulted in the largest effective orifice area at postoperative catheterization. None of the male patients received a valve smaller than 23 mm, and none of the female patients were given a valve smaller than 21 mm. The convexoconcave model of the Bj?rk-Shiley valve was used in 71% of the patients. An outflow patch was required only in 1 patient with concomitant supravalvular stenosis of the aorta. The combination of adequate myocardial protection, comparatively short aortic cross-clamping times, and the use of large, properly oriented Bj?rk-Shiley valves resulted in satisfactory postoperative hemodynamics in all patients. In fact, none of the 196 patients undergoing isolated AVR and only 5 (9%) of the 54 patients undergoing combined procedures required postoperative inotropic stimulation. There were no operative deaths, and all patients left the hospital in good condition. The Bj?rk-Shiley tilting disc valve is a reliable and well-functioning aortic valve substitute that is particularly suited for patients with narrow aortic ostia. With attention to certain details in the insertion technique, encouraging clinical results can be obtained with this prosthesis.     

Comparison of porcine valve xenografts with mechanical prostheses. A 7 1/2 year experience

A total of 479 valve replacements were performed in 469 patients for aortic, mitral, and tricuspid disease. A total of 529 valves were implanted (311 Carpentier-Edwards, 118 Hancock, 94 Bj?rk-Shiley, and six other mechanical valves). Of the 479 operations, 51.1% (245) were carried out in male patients and 48.9% (234) were carried out in female patients. The mean age was 57.6 years; however, 28.6% (137) of the operations were performed in patients over 65 years of age. One hundred five patients (21.9%) had had previous cardiac operations of one type or another. Follow-up was 99.6% and the average length of follow-up was 36.2 months. The overall operative mortality was 5.6%. The operative mortality in the isolated aortic valve replacement group was 2.0% and that in the mitral valve replacement group, 4.4%. There was a 5.9% valve explant rate in the Hancock series; however, no valve explants were required because of valve dysfunction in either the Carpentier-Edwards or the Bj?rk-Shiley groups. The thromboembolic rate in the aortic valve position was 2.4, 1.1, and 2.1 emboli per 100 patient-years in the Hancock, Carpentier-Edwards, and Bj?rk-Shiley groups, respectively. The thromboembolic rate in the mitral valve position was 2.8, 2.2, and 1.0 emboli per 100 patient-years in the Hancock, Carpentier-Edwards, and Bj?rk-Shiley groups, respectively.     

Selection of valve prosthesis, reoperation and late result--surgical technique of reoperation with Bj?rk-Shiley prosthesis

Late result of Bj?rk-Shiley prosthesis selected in the aortic and mitral position for valve replacement was reviewed on 222 cases in our 10 years clinical experience. Late survival was 93.8% (5 yrs), 83% (10 yrs) in the aortic position, 94% (5 yrs) and 80% (10 yrs) in the mitral position. Valve-related complication by Bj?rk-Shiley prosthesis was very low in incidence as compared with that published by other institution with respects to thromboembolism, prosthetic valve endocarditis, reoperation, anticoagulation-related bleeding. Inflammatory aortic valve disease which developed valve detachment in the aortic position with Bj?rk-Shiley valve was treated with double-suture technique in the aortic annulus and fixation of the graft with the inside of sinus of Valsalva, en-bloc reconstruction with composite graft using Bj?rk-Shiley valve inside of the sinus Valsalva without touch to coronary ostium. The other surgical procedure was translocation method using Bj?rk-Shiley prosthesis. Our clinical results suggest that Bj?rk-Shiley prosthesis is still recommended in the aortic and mitral positions from low incidence of valve-related complication and good late survival.     

Late results of mitral valve replacement with the Bj?rk-Shiley prosthesis in children under 16 years of age

The late results of isolated mitral valve replacement were evaluated in 37 children under 16 years of age receiving a Bj?rk-Shiley prosthesis for the treatment of rheumatic mitral lesions. Three patients died, one during the operation and the others 2 months postoperatively. Of the latter two, one had a cerebral hemorrhage and the second had septicemia. The survivors were followed up for a mean of 4.7 years (range 2.8 to 8.9 years). After the operation, all patients were placed on a strict anticoagulant regimen with acenocoumarol. The actuarial survival rate was 92% at the end of the follow-up period. Before valve replacement two patients were in New York Heart Association Class I, 15 in Class II, 18 in Class III, and two in Class IV. After treatment 33 were in Class I and one in Class II. No instances of thromboembolism or infective endocarditis were observed in the survivors. Twenty-one patients underwent cardiac catheterization 2 to 7 years after the operation for evaluation of surgical results. The mean pulmonary artery systolic pressure decreased significantly after operation (p = 0.001), and the mean pulmonary artery wedge pressure decreased to normal values (p = 0.001). A mild mean diastolic gradient across the mitral valve at rest was found after the operation (4.9 +/- 2.4 mm Hg). During isometric exercise this gradient increased to 6.5 +/- 4.6 mm Hg. In two patients a discrete paravalvular leak was demonstrated by cineangiography, but the pulmonary wedge pressure was normal in both. The overall results with the Bj?rk-Shiley prosthesis are encouraging in patients in whom reconstructive operations cannot be performed.     

Valve replacement in children under twenty years of age. Experience with the Bj?rk-Shiley prosthesis

Prosthetic valve replacement in young patients has been reported to be associated with a high mortality and morbidity because of valve-related problems. Of 549 patients undergoing valve replacement with the Bj?rk-Shiley valve prosthesis, 136 were under the age of 20 years. Sixty-four patients were under 16 years of age, the youngest being 6 years old. Of the 136 patients, 61 underwent mitral valve replacement, 50 received an aortic valve, and 25 received both aortic and mitral valves. Overall operative mortality was 10.3%. Late mortality over a follow-up period of 6 months to 8 years was 4.4%. Actuarial survival curves up to 8 years of follow-up are presented. Results obtained in this group are compared with those obtained in 413 patients over 20 years of age operated during the same period. Valve thrombosis was not seen in any patient under 20 years of age, but it occurred in 4.13% of the patients over 20 years of age. The incidence of thromboembolism and anticoagulant-related hemorrhage was very low. There has been no instance of structural failure of the valve. Long-term results are excellent, with 90% of the survivors returning to New York Heart Association Functional Class I. The Bj?rk-Shiley valve gives excellent and durable long-term palliation in young patients requiring valve replacement.     

Clinical results after mitral valve replacement with the Bj?rk-Shiley disc prosthesis

Between September 1971 and June 1985, 230 Bj?rk-Shiley valves were implanted for mitral valve disease at the Department of Surgery, University of Turku. Concomitant cardiac surgical procedures were performed in 35.2% of the cases. The follow-up period was between 1 month-13 years 4 months, with a total follow-up of 986 patient years. The early mortality was 4% in patients with isolated MVR and 10% where concomitant procedures had to be performed. Since the use of cold cardioplegia there has been no mortality for isolated MVR and the mortality rate for patients with concomitant procedures has been 3.9%. During the follow-up the rate of thromboembolism was 0.4 per 100 patient years, that of thrombolic encapsulation 0.4 and anticoagulant-related haemorrhage 0.7. Ninety-five per cent of the patients were free from thrombotic or embolic complications at 5 and 10 years after surgery. The survival rate was 79% at 5 years and 72% at 10 years. Considering these results we still prefer the Bj?rk-Shiley valve in mitral valve replacement.     

Three-year clinical results with the Monostrut Bj?rk-Shiley prosthesis

Between November 1981 and June 1983, 351 patients underwent valve replacement with the Monostrut Bj?rk-Shiley prosthesis. There were 214 aortic valve replacements, 101 mitral valve replacements, and 31 double (aortic and mitral) valve replacements. Four patients had valve implanted in the tricuspid position, and one patient underwent exchange of a valved, extracardiac conduit. Mean age was 61 years (range 2 to 78) and 186 (53%) were male. Concomitant procedures were performed in 52 patients (15%) and 17 (5%) were emergency operations. Early mortality (4.3%) was related to New York Heart Association Functional Class IV, emergency operation, or the presence of a concomitant procedure. Follow-up was 100% and covered 870 patients-years (mean 2.6 years per operative survivor). Postmortem examination was performed in 38 (79%) of the 48 fatalities. Only one patient suffered a sudden, unexplained death. The 3 year survival rate (early mortality excluded) was 88.6% (aortic valve replacement 89.2%, mitral valve replacement 89.3%, and double valve replacement 82.5%). The 3 year freedom from thromboembolism in patients receiving anticoagulants was as follows: aortic valve replacement 97.5%, mitral valve replacement 92.8%, and double valve replacement 100%. There were no instances of valve thrombosis or fatal embolism. In contrast, there were two instances of aortic valve thrombosis among 34 patients having aortic valve replacement without anticoagulation. The 3 year freedom from valve failure (modified Stanford definition) was as follows: aortic valve replacement 96.0%, mitral valve replacement 93.9%, and double valve replacement 89.7%. There were no mechanical failures. In conclusion, the Monostrut Bj?rk-Shiley valve showed a low incidence of complications. There were no mechanical failures, no fatal emboli, and, when anticoagulants were administered, no valve thromboses.     

Bj?rk-Shiley and Carpentier-Edwards valves. A comparative analysis

Between January 1977 and December 1982, 986 Bj?rk-Shiley and 744 Carpentier-Edwards valves were implanted in 774 and 620 patients, respectively, at the same institution. All Bj?rk-Shiley patients and 57% of patients with a Carpentier-Edwards valve in the mitral position received long-term anticoagulation. Mean follow-up was 3.2 years (range 0 to 8.8) in the Bj?rk-Shiley patients and 3.5 years (range 0 to 8.2) in the Carpentier-Edwards group. There was no significant difference between the two groups in hospital mortality (Bj?rk-Shiley 7.6%; Carpentier-Edwards 6.0%), overall incidence of embolism (Bj?rk-Shiley 1.4 per 100 patient-years; Carpentier-Edwards 1.6% py), endocarditis (Bj?rk-Shiley 0.6% py; Carpentier-Edwards 0.8% py), periporsthetic leak (Bj?rk-Shiley 1.6% py; Carpentier-Edwards 1.4% py), anticoagulant-related complications (Bj?rk-Shiley 0.3% py; Carpentier-Edwards 0.1% py), valve failure (Bj?rk-Shiley 0.78% py; Carpentier-Edwards 0.68% py), reoperation for complication (Bj?rk-Shiley 1.68% py; Carpentier-Edwards 1.22% py), and late mortality (Bj?rk-Shiley 3.1% py; Carpentier-Edwards 3.0% py). Actuarial freedom from valve-related events was similar in the two groups. In the aortic position, freedom from embolism was significantly better in the Bj?rk-Shiley group than the Carpentier-Edwards group (Bj?rk-Shiley 99% at 3 and 5 years; Carpentier-Edwards 96% and 92% at 3 and 5 years; p = 0.023). In the mitral position, the overall incidence of reoperation was higher in the Bj?rk-Shiley group (1.78% py) than in the Carpentier-Edwards group (0.48% py) (p = 0.004). Actuarial analysis shows this difference to be confined to the first 6 years of follow-up. The commonest indication for reoperation was valve failure in both groups. However, when analysis is confined to this indication, the difference between the reoperation incidence in the mitral position becomes insignificant (Bj?rk-Shiley 0.85% py; Carpentier-Edwards 0.29% py; p = 0.085). This study confirms the satisfactory performance of both the Carpentier-Edwards and Bj?rk-Shiley valves in the short and middle term and indicates no clear-cut advantage for either prosthesis.     

Results of multiple valve repair. A clinical study of 81 patients

A report is presented of 50 men and 31 women, mean age 50.3 years, who underwent surgery for multivalvular cardiac disease in 1973-1987. NYHA function class was III-IV in 88% of the patients. The most common procedures were aortic + mitral valve replacement (81%), aortic + mitral valve replacement + coronary artery bypass grafting (5%), aortic valve replacement + tricuspid valvuloplasty (5%) and mitral valve replacement + tricuspid valvuloplasty (5%); 95% of the implanted valves were of Bj?rk-Shiley disc type. Nine patients died perioperatively, six due to myocardial infarction and/or low cardiac output. Postoperative bleeding necessitated resternotomy in three cases. Follow-up was complete, with a mean observation time of 4.5 years (a total of 323 patient years). The incidence of thrombotic valve encapsulation was 0.6/100 patient years. Corresponding figures for anticoagulant-related haemorrhage, prosthetic valve endocarditis and paraprosthetic leakage were 0.9, 1.2 and 1.2. In our experience, the rate of late complications after multivalvular reconstruction using Bj?rk-Shiley prosthesis is acceptable if anticoagulant therapy is correctly employed.     

A five-year appraisal and hemodynamic evaluation of the Bj?rk-Shiley Monostrut valve

Two hundred forty-four Bj?rk-Shiley Monostrut valves were implanted in 225 consecutive patients from October 1983 to December 1988. Aortic valve replacement was performed in 90 patients, mitral valve replacement in 118, and double valve replacement in 16 patients. One patient had tricuspid valve replacement. There were 100 female patients and 125 male patients with a mean age of 54 years (range 2 to 71 years). Present data were completely available for all patients. The cumulative follow-up was 541 patient-years with a mean of 2 years, 5 months. The closing date for follow-up was July 1989, and the closing interval was 2 months. The early mortality rate was 3.1%, and the late mortality rate, 3.1%. The 5-year survival rate was 88% +/- 2.0%: 87% +/- 3.0% for aortic valve replacement, 91% +/- 3.3% for mitral valve replacement, and 75% +/- 9.6% for double valve replacement. The actuarial rates of freedom from thromboembolism at 5 years were 93% +/- 3.2% for aortic, 96% +/- 1.4% for mitral, and 94% +/- 6.1% for double valve replacement. There were no instances of structural valve deterioration. Actuarial rate of freedom from valve-related morbidity and mortality was 86% +/- 2.0% at 5 years: 86% +/- 9.5% for aortic, 87% +/- 3.3% for mitral, and 75% +/- 7.3% for double valve replacement. Effective valve areas (average) of 12 mitral and 12 aortic valve prostheses were calculated at rest and during bicycle exercise: 2.4 cm2 at rest and 2.8 cm2 during exercise in 27 mm aortic valves, 2.4 cm2 at rest and 3.0 cm2 during exercise in 25 mm aortic valves, 2.0 cm2 at rest and 2.4 cm2 during exercise in 27 mm mitral valves, and 2.6 cm2 at rest and 2.5 cm2 during exercise in 29 mm mitral valve. On the basis of our follow-up period of 5 years, we have judged the Bj?rk-Shiley Monostrut valve reliable, with a low incidence of valve-related morbidity and with acceptably satisfactory hemodynamic characteristics at rest and during exercise.     

An eighteen-year evaluation of the Bjork-Shiley valve prosthesis

We evaluated the long-term (18 years) results of 356 patients undergoing valve replacement with Bj?rk-Shiley valve prosthesis (aortic, 212; mitral 120; double valve, 24) between 1970 and 1988. Actuarial survival rates were 90% (18 years) for AVR, 80% 'years) for MVR and 90% (8 years) for DVR. Actuarial rates of thromboembolism were 99% (18 years) for AVR, 98% (8 years) for MVR and 94% (8 years) for DVR. Actuarial rates of freedom from events (including valve failure, thromboembolism, reoperation and prosthetic valve endocarditis) were 82% (18 years) for AVR, 95% (8 years) and 94% (8 years) for DVR. There were no differences in these results among spherical disc, convexo-concave disc and monostrut valve. In conclusion, this study demonstrated that Bj?rk-Shiley valve showed a low incidence of postoperative events. These results endorse our choice of the Bj?rk-Shiley.     

Mechanical heart valve prostheses: sound level and related complaints.

In a randomised study, we investigated the sound production of mechanical heart valve prostheses and the complaints related to this sound. The CarboMedics, Bj?rk-Shiley monostrut and StJude Medical prostheses were compared. A-weighted levels of the pulse-like sound produced by the prosthesis were measured in 25 patients after aortic valve replacement. Additionally, 141 patients, 117 after aortic valve replacement, 20 after mitral valve replacement and 4 after double valve replacement were interviewed. The average sound pulse pressure levels were 46.0 +/- 2.9 dB(A) in the Carbomedics group, 55.4 +/- 1.2 dB(A) in the Bj?rk-Shiley monostrut group and 44.1 +/- 4.4 dB(A) in the StJude Medical group, measured at a distance of 1 cm from the chest. The Bj?rk-Shiley monostrut was louder than the other two prostheses (p less than 0.0005). Twenty (14.2%) of all patients had complaints related to the valve sound such as sleeping disturbances, irritation, nervousness or fear. Significantly more patients with a Bj?rk-Shiley monostrut could hear their valve or had complaints when compared to the other two prostheses. Younger patients and patients with a mitral valve prosthesis could hear their valve more often than older patients or patients after aortic valve replacement. We conclude that sound characteristics and related complaints differ considerably among heart valve prostheses.     

Comparative clinical results with Omniscience (STM1), Medtronic-Hall, and Bj?rk-Shiley convexo-concave (70 degrees) prostheses in mitral valve replacement

The intermediate clinical results of 289 patients undergoing isolated mitral valve replacement with three different low-profile mechanical prostheses have been retrospectively analyzed and compared. Between June, 1980, and September, 1983, 70 patients received the Omniscience prosthesis, 159 patients the Medtronic-Hall valve, and 60 patients the convexo-concave 70 degree Bj?rk-Shiley prosthesis. Hospital mortality was 15% for the Bj?rk-Shiley group, 4.4% for the Medtronic-Hall group, and 7.1% for the Omniscience group. Cumulative follow-up was 88 years (mean 1.7 years) for the Bj?rk-Shiley, 229 years (mean 1.5 years) for the Medtronic-Hall, and 223 years (mean 3.3 years) for the Omniscience group. All patients were placed on a program of anticoagulant therapy (dicumarol) postoperatively. Actuarial survival rates (+/-SE) 2 years postoperatively were comparable for the three groups: Bj?rk-Shiley, 90% +/- 4.7%; Medtronic-Hall, 93% +/- 2.2%; and Omniscience, 88% +/- 4.1% (p = NS). Late mortality, expressed at linearized rates (percent patient-year +/-SE), was 3.4% +/- 1.9% for the Bj?rk-Shiley group, 1.7% +/- 0.8% for the Medtronic-Hall group, and 3.6% +/- 1.2% for the Omniscience group (p = NS). Actuarially determined rates of freedom from thromboembolic complications (systemic embolism and valvular thrombosis) 2 years postoperatively were 97% +/- 2.2% for the Bj?rk-Shiley group, 94% +/- 2.1% for the Medtronic-Hall, and 84% +/- 4.7% for the Omniscience group (p = 0.05, Omniscience versus Medtronic-Hall; p = 0.02, Omniscience versus Bj?rk-Shiley) The actuarial probability of being free from reoperation 2 years postoperatively was 92 +/- 3.5 for the Bj?rk-Shiley group, 92 +/- 2.9 for the Medtronic-Hall group, and 82 +/- 3.9 for the Omniscience group (p = 0.04). The major cause for reoperation in the Omniscience group was valve thrombosis (seven patients), yielding a linearized incidence (+/-SE) of 3.1 +/- 1.1 (p = 0.01). No statistically significant differences were obtained regarding the incidence of prosthetic infective endocarditis or perivalvular leak. Overall rates of anticoagulant-related hemorrhage were comparable for the three groups.     

Mechanical failure of the Bj?rk-Shiley valve. Incidence, clinical presentation, and management

The experience after implantation of 3,334 Bj?rk-Shiley valves over a 15 year period is described. With a 99.2% follow-up (covering 17,511 patient-years, mean follow-up time 6.3 years) and an autopsy rate of 75% among all fatalities, altogether 19 cases of mechanical failure were documented. There were no mechanical failures among the standard Delrin Bj?rk-Shiley valve (n = 271), the aortic standard Pyrolyte Bj?rk-Shiley (n = 739), or the Monostrut Bj?rk-Shiley valve (n = 377). One of the mitral standard Pyrolyte valves (n = 430) fractured. Among the 1,461 convexo-concave valves, 18 fractured (6/884 with an opening angle of 60 degrees and 12/577 with an opening angle of 70 degrees). The actuarial incidence of mechanical failure at 5 years was 0.6% (with an upper 95% confidence limit of 1.2%) for the 60 degree convexo-concave valve and 2.8% (upper 95% confidence limit of 4.4%) for the 70 degree convexo-concave valve (p less than 0.01). Two groups of valves were especially affected by this complication; the 23 mm aortic 60 degree convexo-concave valve (5 year actuarial incidence 2.2%, upper 95% confidence limit 4.7%) and the 29 to 31 mm mitral 70 degree convexo-concave valve (8.3%, upper 95% confidence limit 14.2%). The hazard function presently indicates a constant (60 degree convexo-concave) or decreasing (70 degree convexo-concave) tendency for mechanical failure. The time interval between the first symptom of mechanical failure and circulatory collapse was significantly (p less than 0.01) shorter after aortic failure than after mitral failure, and no patient with a fractured aortic prosthesis survived long enough to undergo reoperation. The incidence of mechanical failure among patients dying suddenly (but with an autopsy) was 9.6% (95% confidence limits 4.9%-16.6%), and most cases of sudden death were unrelated to the prosthesis. The management of patients with suspected mechanical failure is described. Prophylactic re-replacements are discussed but cannot be generally recommended at present.     

Comparative analysis of long-term results with porcine-aortic, bovine pericardial and tilting disc valves

The three series with the first-generation valve prostheses were reviewed for long-term clinical evaluation in isolated aortic and mitral valve replacement. Hancock porcine xenograft was implanted in 71 patients from 1977 to 1979, ionescu-Shiley pericardial xenograft (standard model) in 271 patients from 1979 to 1983, and Bjork-Shiley tilting disc valve in 194 from 1978 to 1986. In aortic position, no any significant difference among three valve types could be demonstrated in the actuarial survival and freedom from thromboembolism and valve infection, while the actuarial freedom from valve dysfunction in lonescu-Shiley valve was significantly lower than that in other two valves. Bj?rk-Shiley valve in mitral position showed satisfactory clinical performance in terms of valve-related complications and survival in comparison with two types of bioprosthetic valves. In our conclusion at present time, Bj?rk-Shiley valve is suitable for the first choice of both aortic and mitral valve prostheses. In case of valve replacement with a bioprosthesis, however, porcine aortic valve is a better choice for aortic, and bovine pericardial valve likely for mitral replacement.     

Clinical experience with the Bj?rk-Shiley integral monostrut heart valve prosthesis in the aortic and mitral position

From May 1982 to May 1985, 174 Bj?rk-Shiley integral monostrut (BSIM) heart valve prostheses were implanted in 160 patients. Eighty-eight valves were placed in mitral and 86 in aortic position. There were 92 males and 78 females with a mean age of 54.1 years (140 patients were in NYHA class III or IV (87.5%]. Single valve replacement was performed in 116 (72%) patients, 30 (19%) underwent multiple valve procedures and in 14 (9%) valve replacement was combined with coronary artery bypass surgery. There were no intraoperative deaths. Six patients died within the first month after surgery. One hundred and fifty-two (98.7%) patients were followed for a total of 190 patient years (average 14.8 months per patient). There were 8 late deaths (4.2 per 100 patient-years), 5 of these were valve related. Valve related complications were observed in 9 patients (4.5 per 100 patient-years). The overall incidence of peripheral embolization was 2.6 per 100 patient years. At the time of the follow-up study 136 (94%) patients were in functional class I and II. Fourteen patients with isolated AVR and six with MVR underwent hemodynamic evaluation on an average of 12 and 10 months after surgery. The early results suggest that the BSIM prosthesis represents a promising alternative in heart valve replacement, because there were no mechanical failures, thromboembolic complications are rare and hemodynamic performance is good.     

Aortic valve replacement with the Bj?rk-Shiley tilting disc valve prosthesis. Clinical experiences in 50 cases.

Single aortic valve replacement with the Bj?rk-Shiley tilting disc valve prosthesis has been performed in 50 patients since April 1971. None of the total of six deaths (12.0%) was attributable to malfunction of the prosthesis or to embolic complications. Follow-up examination showed insignificant or moderate prosthetic regurgitation in two patients and moderate paravalvular leakage in one patient. A slight intravascular haemolysis was found in two cases, one of them without marked regurgitation, and a slight reversible cerebral thrombo-embolism in two. Clinical improvement was observed in 43 of the 44 survivors during the 6 to 12 months of follow-up. Objective evidence of improvement was verified by cardiac catheterization following the replacement of aortic valve with the Bj?rk-Shiley tilting disc prosthesis.     

Replacement of a thrombosed valve after the Bentall procedure

A 50-year-old man developed thrombosis in the valve of a Bj?rk-Shiley prosthesis that had been used for composite graft replacement of the aortic valve and ascending aorta 8 years previously. The thrombosed valve was removed, and because of the narrow aortic valve ring, it was replaced using patch enlargement of the aortic annulus without replacement of the conduit.