Comparison of outcome after valve replacement with a bioprosthesis versus a mechanical prosthesis: initial 5 year results of a randomized trial.

The Veterans Administration Cooperative Study on Valvular Heart Disease was organized to compare survival and incidence of valve-related complications between patients receiving a bioprosthesis (the Hancock porcine heterograft) and a mechanical prosthesis (the Björk-Shiley spherical disc valve). Five hundred seventy-five patients undergoing single aortic or mitral valve replacement were randomized at surgery to one of the two valve types. At an average follow-up of 5 years (range 3 to 8) there are no statistically significant differences in survival between patients with the two valve types in the aortic valve replacement group. There is a statistically nonsignificant trend toward improved survival in patients undergoing mitral valve replacement with a bioprosthesis compared with a mechanical prosthesis (5 year survival probability was 0.70 +/- 0.05 and 0.58 +/- 0.06, respectively). Fatal and nonfatal valve-related complications occurred significantly less frequently in patients with a bioprosthesis compared with a mechanical prosthesis for both mitral and aortic valve replacement. Five year complication-free probability was 0.67 +/- 0.05 and 0.45 +/- 0.06, respectively, for patients with mitral valve replacement and 0.63 +/- 0.04 and 0.53 +/- 0.04, respectively, for those with aortic valve replacement. The difference in overall complication rates was largely due to the increased number of clinically significant but nonfatal bleeding episodes in patients receiving a mechanical prosthesis. Adjustment for differences in baseline characteristics between patients receiving a mitral mechanical prosthesis and a mitral bioprosthesis reduced the statistical significance of the difference in both mortality and complications.

The third generation Carpentier-Edwards bioprosthesis: early results.

The current status of valve replacement was reviewed by analyzing six groups of 100 consecutive patients, each receiving the standard Carpentier-Edwards bioprosthesis, the Starr-Edwards valve or the Björk-Shiley valve in the mitral or aortic position and operated on by the same surgeons in the same institution during an identical time frame. Data were evaluated for valve failure, reoperation, thromboembolism and valve-related deaths. Long-term results up to 9 years showed the superiority of bioprostheses over mechanical valves in terms of valve-related deaths and thromboembolic and anticoagulant complications for a similar rate of valve failure. Persistent drawbacks associated with valvular bioprostheses, namely, transvalvular gradients, limited durability and tissue calcification in young patients, led to continual improvements in valve design and preservation techniques and the development of the third generation Carpentier-Edwards bioprosthesis: the supraanular porcine valve and pericardial valve. The supraanular porcine valve was designed with the aim of decreasing the transvalvular gradient, decreasing turbulence, increasing longevity and decreasing calcification. The pericardial valve was designed with the aim of improving hemodynamics in small-sized orifices, improving mounting techniques to avoid fixation sutures at the commissures, achieving a flexible stent and improving preservation. Between July 1980 and October 1984, there were 391 supraanular porcine and 61 pericardial valves implanted. The supraanular valves were used for three purposes: isolated aortic, isolated mitral and mitral valve replacement associated with tricuspid anuloplasty. The pericardial valves were used for isolated aortic valve replacement. Short-term results (1 to 4 years) are presented concerning the clinical use of these third generation bioprostheses.

Isolated replacement of a prosthesis or a bioprosthesis in the mitral valve position.

The operative results of 249 mitral valvular reoperations performed in 215 patients from 1974 through 1986 were reviewed to identify groups at greater risk. Two to 4 reoperations were performed in 28 patients. The mean interval between the first and second valve procedures was 47 +/- 40 months. The most common indications for reoperation were degeneration of bioprostheses (44%) and thrombosis of mechanical prostheses (26%). Thirty patients (12%) died. This rate was significantly higher (p less than 0.02) than that for primary valve procedures performed during the same period. The mortality rate for elective reoperations was 7%. Mortality rates were higher among patients with prosthetic valve endocarditis (6 of 17 cases, 35%), in those undergoing operation on an emergency basis (19 of 82, 23%) and when tricuspid valve replacement or anuloplasty was also performed (9 of 38, 24%) (p less than 0.02). No significant correlation was found between mortality rates and the age or sex of the patients and the types of prosthesis used originally.

Isolated replacement of a prosthesis or a bioprosthesis in the aortic valve position.

The operative results of 203 aortic prosthetic valve reoperations performed in 175 patients from 1974 through 1986 were reviewed to identify groups at greater risk. Two to 4 reoperations were performed in 23 patients. The mean interval between the first and second valve procedures was 74 +/- 57 months. The most common indications for reoperation were thrombosis of mechanical prostheses (25%), degeneration of homografts (22%) and mechanical valve dysfunction (19%). Eighteen patients (9%) died. This mortality rate was significantly higher (p less than 0.05) than that of primary valve procedures performed during the same period. Mortality rates were higher among patients with prosthetic valve endocarditis (6 of 26 cases, 23%) and among those who underwent operation on an emergency basis (15 of 20, 25%). No significant correlation was found between mortality rates and the age or gender of the patients and the types of prostheses used originally.

Long-term results of tricuspid valve replacement and the problem of prosthetic valve thrombosis.

Observations in 71 patients having tricuspid valve replacement over a 14-year period are described. The operative mortality rate was 10% and the actuarial survival rate was 73% at 5 years and 47% at 10 years. Survival was unaffected by the number of valves replaced or the type used (27 Starr-Edwards, 32 Björk-Shiley, 8 Lillehei-Kaster, and 4 porcine xenografts). Complications were common: 3 deaths were related to anticoagulation and 1 was due to a systemic embolus. Six patients required permanent pacing. There was a very high incidence of thrombosis of the prosthetic tricuspid valve. Twenty percent of the tilting disc valves thrombosed, compared with 4% of the Starr-Edwards valves (p less than 0.05). Symptoms of thrombosis were usually insidious, and its diagnosis was often delayed. There was a continuing risk of this complication, and presentation occurred up to 12 years after the original operation. Thrombolytic therapy with streptokinase was successful in 1 of 2 patients. Replacement of the thrombosed prosthetic valves was carried out without mortality in 8 patients.

Anatomic analysis of removed prosthetic heart valves: causes of failure of 33 mechanical valves and 58 bioprostheses, 1980 to 1983.

The details of heart valve prosthesis-associated problems are not widely known. This study investigated the etiologies of the failures of 91 valves, 33 mechanical prostheses and 58 bioprostheses, obtained at reoperation (83) or autopsy (eight) at the Brigham and Women's Hospital during the 42-month period from mid- 1980 through 1983, one to 264 months (mean, 72 months) after valve replacement. Analysis was by gross, histologic, radiographic, and microbiologic examination, as well as review of clinical records. Overall causes of failure included paravalvular leak (15 per cent), thrombosis (7 per cent), tissue overgrowth (8 per cent), degeneration or mechanical failure (43 per cent), and endocarditis (19 per cent). Endocarditis and paravalvular leak were equally frequent with mechanical prostheses and bioprostheses. In addition, thrombosis (18 per cent), tissue overgrowth (21 per cent), and structural failure (12 per cent) were all important failure modes for mechanical prostheses. Sterile degeneration was the overwhelming cause of failure for bioprostheses, accounting for the failure of 35 of 58 (60 per cent) of those recovered. Sterile degeneration took several forms: calcification, with or without cuspal tears (27 cases, 47 per cent of bioprostheses; mean, 77 months, range, 44 to 108 months) and cuspal defects without calcification (eight cases, 14 per cent; mean, 59 months, range, eight to 122 months). In general, calcification increased with time after implantation, but the propensity for the mineralization of bioprostheses varied widely among patients. Four torn valves that had been in place for more than six years had radiographically undetectable calcific deposits. The results of this study indicate that paravalvular leak and endocarditis are frequent causes of failure for all valve types. No clear failure mode predominates with mechanical valve prostheses, although some designs have specific inherent limitations. In contrast, degeneration, especially that related to mineralization, is the most important cause of the late failure of contemporary bioprostheses.

In-hospital and long-term outcome after porcine tricuspid valve replacement.

Porcine bioprostheses are often used for tricuspid valve replacement, yet the long-term outcome after this procedure is not well documented. Therefore, the records of 129 patients undergoing tricuspid valve replacement with Carpentier-Edwards (n = 88) or Hancock (n = 41) prostheses between 1975 and 1993 were reviewed. The operation required a repeat median sternotomy in 66 of 129 (51%) patients, whereas 67 of 129 (52%) underwent double or triple valve replacement. Operative mortality was 14% (2/14) in patients undergoing first-time isolated tricuspid valve replacement and 27% (35/129) overall. Survival at 5, 10, and 14 years was 56% +/- 5%, 48% +/- 5%, and 31% +/- 9%, and freedom from tricuspid reoperation at 5, 10, and 14 years was 96% +/- 3%, 93% +/- 4%, and 49% +/- 17%. No valve thrombosis was observed. In this largest reported series of porcine bioprostheses in the tricuspid position, long-term freedom from valve-related events was excellent because of a low incidence of valve thrombosis and a valve durability of 13 to 15 years in a population with limited life expectancy.

Year of operation as a risk factor in the late results of valve replacement.

The actuarial thromboembolic rates of aortic and mitral silicone ball valves used during the second decade of cardiac valve replacement are significantly lower than the rates for the same prostheses implanted during the first decade, as shown in the following table: (Formula: see text). The embolus-free rates are significantly different (p < 0.01) in both the mitral and aortic series. Five-year embolus-free rates for the composite-strut caged-ball, Björk-Shiley tilting disc, and porcine xenograft valves all fall in the range of from 81% to 92% for the mitral position and from 91% to 97% for the aortic. Thus the standard silicone ball-valve prosthesis, used during the current era, has a thromboembolic risk as low as that reported with other concurrently utilized valve substitutes. This striking reduction in thrombogenicity demonstrates that the time frame of implantation must be considered when evaluating the results of cardiac valve replacement.

Stentless porcine aortic root: valve of choice for the elderly patient with small aortic root?

The Medtronic Freestyle bioprosthesis is a stentless porcine aortic root cross-linked in dilute glutaraldehyde solution with stress-free fixation for the valve leaflets. It has been treated by a process in which amino oleic acid is used to reduce the potential for calcification. As a complete aortic root, it has the same versatility as the aortic homograft but has the advantage that it is readily available in all sizes to the implanting surgeon. Between January 1993 and May 1994, we implanted 64 Freestyle bioprostheses as aortic valve replacements using a freehand technique; 5 size 19 mm, 15 size 21 mm, 16 size 23 mm, 13 size 25 mm, and 15 size 27 mm valves were used. There were 35 men and the mean age was 75.7 years (64 to 84 years). The operative mortality was 3.1% (2/64). Echocardiograms at the time of discharge revealed mean aortic valve gradients ranging from 18.2 mm Hg for 19 mm to 10.3 mm Hg for 27 mm valves. Effective orifice areas ranged from 1.0 cm2 for 19 mm to 2.0 cm2 for 27 mm valves. No patient had more than trace aortic insufficiency. Our early experience with this new stentless bioprosthesis shows it to have excellent hemodynamics especially in the smaller valve sizes. Using this valve in patients who have a small aortic root and require a tissue valve avoids the need for aortic root enlargement procedures.

Six- to ten-year follow-up of patients with the Hancock cardiac bioprosthesis. Incidence of primary tissue valve failure.

From June, 1974, through June, 1978, 547 porcine xenografts (299 mitral, 239 aortic, eight tricuspid, and one pulmonary) were inserted in 459 selected patients who survived the operation and were considered at risk for primary tissue valve failure. Ninety-two instances of primary tissue valve degeneration occurred in 82 of the 459 patients. In patients operated on 10 years ago, 28% of the valves implanted in the mitral position (5/18) and 33% in the aortic position (4/12) failed. These percentages decreased to 24% (21/89) and 26% (15/57) for those implanted in 1975, 15% (13/85) and 16% (9/57) for those implanted in 1976, 13% (9/71) and 15% (12/82) for 1977, and 8% (3/36) and 3% (1/31) for 1978. None of the tricuspid or pulmonary valves have failed. The rate of valve survival without primary degeneration was 70% +/- 6% for the mitral and 69% +/- 7% for the aortic prostheses at 10 years of follow-up. Of the 10 valves implanted in patients younger than 20 years of age, 40% of the mitral and 60% of the aortic valves failed. This rate is 26% for mitral and 42% for aortic for the 21 to 30 year group, 20% and 19% for 31 to 40 years, 9% and 13% for 41 to 50 years, 20% and 6% for 51 to 60 years, and 11% and 0% for 61 to 70 years. The average interval between placement and explantation or death was 74 months (range 10 to 112) for valves in the mitral position and 78 months (range 13 to 117) for valves in the aortic position. We believe these current data should have some bearing of practical import not only when comparing different types of bioprostheses but especially when recommending the appropriate valve replacement for the individual patient.

Porcine heterograft valve replacement in children.

From 1973 to 1980, 49 patients under 18 years of age survived cardiac valve replacement with Hancock porcine heterografts. Complete follow-up has been obtained on 44 patients (90%) in whom 46 valves were placed. There were 30 boys and 14 girls with an age range of 2 to 18 years (mean 10.0 years). Severe prosthetic valvular dysfunction requiring valve replacement occurred in eight valves in seven patients at 15 to 60 months postoperatively (mean 34.1 months), yielding a calculated replacement rate of 7.1% per patient-year. All eight valves demonstrated severe calcification with stenosis, two valves had significant insufficiency secondary to leaflet disruption, and one valve had a large leaflet perforation. Thirty-one patients with valves in place at 7 to 90 months (mean 38.4 months) are alive, but six have clinical evidence of progressive valvular dysfunction. The mean age at the time of the original Hancock valve placement of the group of patients having undergone replacement of a failed prosthesis together with those with clinical evidence of prosthetic dysfunction was 8.0 years, which is significantly less than that of the remaining group of patients with normally functioning valves (mean 11.2 years, p = 0.043). Actuarial curves demonstrate a predicted replacement-free rate of 87.4% +/- 5.9% at 3 years. 82.3% +/- 7.5% at 4 years, and 58.5% +/- 15.7% at 5 years. On the basis of these data and other reports of early failure in the literature, we have discontinued the routine use of Hancock porcine heterografts for cardiac valve replacement in children in favor of mechanical prostheses.

Long-term follow-up of the Ionescu-Shiley mitral pericardial xenograft.

In a group of 40 patients discharged from the hospital after mitral valve replacement with an Ionescu-Shiley pericardial xenograft from January, 1977, to December, 1980, seven instances of valve failure occurred. This unprecedented incidence of bioprosthetic dysfunction after mitral valve replacement with the Ionescu-Shiley pericardial xenograft led us to update the follow-up of our patients receiving this valve in the mitral position. The results of our survey showed, at 6 years postoperatively, an actuarial survival rate of 72%, an actuarial probability of being free from emboli of 62%, and an actuarial freedom from prosthetic failure of 60%. The explanted valves showed complete absence of the neoendothelial lining of the Dacron-covered frame and lesions resembling those observed in Ionescu-Shiley pericardial xenografts removed from our fatigue test system after a mean of 29 +/- 17 X 10(6) cycles. This similarity prompted a classification of tears occurring in the mitral Ionescu-Shiley pericardial xenograft, which is of extreme importance, since the clinical presentation and outcome of patients with a failing valve differs according to the type of rupture. The lesions of the cusp observed in clinical specimens were possibly related to the continuous trauma of the tissue against the bare Dacron cloth during closure of the valve. It is concluded that (1) actual durability and thrombogenicity of the Ionescu-Shiley pericardial xenograft in the mitral position needs to be carefully reassessed, (2) close follow-up of such patients by clinical and two-dimensional echocardiographic evaluation is advisable after the third postoperative year, and (3) failure of the mitral Ionescu-Shiley pericardial xenograft may occur suddenly, and awareness of this complication is the clue to prompt recognition and treatment of such patients.

Early and late prognosis after reoperation for prosthetic valve replacement.

From 1969 to 1983, 89 patients underwent replacement of a prosthetic heart valve, an average of 66 months after initial implantation, because of primary failure of the prosthesis in 39 patients (44%), endocarditis in 16 (18%), systemic valve-related complications in 16 (18%), and periprosthetic leaks in 13 (15%). In the remaining five patients (5%), a prosthesis was removed concomitantly with the replacement of another native heart valve. A mechanical valve was replaced in 64 cases (72%) and a bioprosthesis in 25 (28%). Forty-six of the prostheses (52%) were in the mitral position, 37 (42%) were in the aortic position, and six patients (6%) underwent replacement of two prostheses. Preoperatively, four patients were in Functional Class I, 21 in Class II, 37 in Class III, and 27 in Class IV. There were 19 early deaths (21.3%). Early mortality was significantly higher with aortic (35.1%) than with mitral prosthetic valve replacement (8.7%, p less than 0.01). Preoperative diagnosis had a significant correlation with mortality, which was higher with infective endocarditis (62.5%) than with all other indications for operation (12.3%, p less than 0.001). No correlation was found with the preoperative clinical class of the patients. During the time period of this study, there was a marked decline in the mortality rate, which decreased from 29.2% prior to 1979 to 7.4% during the last 2 years (p less than 0.05). Actuarial survival was 60% at 5 years and 38% at 10 years after reoperation. Among the 53 survivors followed up for an average of 39 months, 47 (88.9%) remained in Class I or II and six were in Class III (11.3%) at last follow-up. A second prosthetic valve replacement (third valve replacement) was required in eight patients, three of whom died at re-replacement. Recent improvements in myocardial protection techniques, in the treatment of prosthetic valve endocarditis, and increased surgical experience have contributed to decrease the risk of reoperation for prosthetic valve replacement. Late results are similar to those of a first valve implantation.

Clinical durability of the Hancock porcine bioprosthetic valve.

The principal feature of the Hancock xenograft bioprosthesis which remains to be completely defined is long-term durability. This report provides extended data regarding valve durability derived from a data base of 1,407 patients (707 aortic [AVR] and 700 mitral [MVR] replacements) who received Hancock bioprostheses between 1971 and 1979; cumulative duration of follow-up was 1,732 patient-years for AVR and 1,843 for MVR patients, with a maximum follow-up duration of 8.4 years. One hundred seventy-nine patients were followed for more than 5 years and 67 for more than 6 years. Valve failure was defined on the basis of one or more of the following criteria: (1) postoperative development of a new regurgitant murmur, (2) thrombotic valvular occlusion, (3) infective endocarditis resulting in reoperation or death, and (4) hemodynamic valvular dysfunction confirmed by catheterization and resulting in reoperation or death. Twenty-one such failures occurred among all AVR patients and 23 among all MVR patients. The actuarial probability of freedom from valve failure (all causes) was 95.4% +/- 1.2% (+/- SEM) for adult AVR patients 5 years postoperatively and 90.9% +/- 2.6% for adult MVR patients 6 years postoperatively. The probability of freedom from primary tissue failure in adults was 99% +/- 1% in AVR patients at 5 years and 94.3% +/- 2.4% in MVR patients at 6 years. The linearized incidence of primary tissue failure in children (< 15 years old) was 9.8% per patient-year (combined AVR and MVR patients), compared to 0.2% per patient-year among all adult patients in the analysis. The combined actuarial incidence of primary tissue failure among adults with AVR and MVR was 98.6% +/- 0.7% at 5 years and 94.2% +/- 2.3% at 6 years; thus there appears to be a slight acceleration in the rate of valve tissue failure between 5 and 6 years after operation. The incidence of failure, however, remains acceptably low through 6 years of follow-up, and continued clinical use of the xenograft bioprosthesis seems warranted.

Late failure of porcine valve heterografts in children.

Heterograft porcine valves have gained wide acceptance in replacement of diseased cardiac valves, and their clinical performance in adults has been very satisfactory over follow-up periods of up to 8 years. Valve replacement in children is relatively infrequent and experience with porcine xenografts is necessarily small. Our combined experience at three university hospitals has been with 25 children, 17 months to 16 years of age, who have been followed for 10 to 54 months (mean follow-up 33 months). Porcine valves were used to replace the aortic valve in nine, the mitral valve in seven, both valves in two, the tricuspid valve in two, and the pulmonary valve in five patients. Severe bioprosthetic valve dysfunction has occurred in five (20%) of these patients so far and necessitated replacement because of severe stenosis in mitral (two) or aortic (three) valve prostheses at 18 to 45 months after implantation; one postoperative death occurred among the five reoperations. Pathological examination showed extensive fragmentation of collagen with focal heavy calcification and degeneration. In addition we have encountered deterioration and calcification of two porcine valves in 23 valved conduits followed for 12 to 70 months (mean 43 months), requiring removal and replacement of the valves 65 and 67 months after implantation. This experience indicates a disquietingly high incidence of relatively early failure of porcine xenograft valves in children. This is significantly higher than the failure rate observed in adult patients. The failure rate is not consistently related to the small size of an implanted valve which becomes relatively narrow with the growth of the patient, leading to excessive turbulence and trauma to the prosthesis. Other factors, including increased turnover of calcium and accelerated rejection in growing children, may contribute to these failures and should be examined in order to improve long-term results. A satisfactory performance would make heterografts the ideal valvular prosthesis in children, since anticoagulation is avoided.

Can the results of contemporary aortic valve replacement be improved?

Although the results of contemporary aortic valve replacement are excellent, cardiac surgeons must identify the factors that predict postoperative morbidity and mortality to develop alternative strategies for high-risk patients. Two hundred seventy-seven consecutive patients undergoing isolated aortic valve replacement between 1982 and 1984 were evaluated. Thirty-seven clinical and 13 preoperative hemodynamic variables were analyzed by univariate and multivariate statistics to determine the risk factors for postoperative morbidity and mortality. The operative mortality was 3%, the incidence of a postoperative low output syndrome was 12%, and the incidence of a perioperative myocardial infarction was 5%. A multivariate, logistic regression analysis found that age was the only the only independent predictor of mortality. Three factors independently predicted postoperative low output syndrome: age, the presence of coronary artery disease, and the peak systolic gradient in patients with aortic stenosis. Patients with aortic stenosis had a higher incidence of postoperative ventricular dysfunction (17%) than those with mixed valvular disease (9%) or aortic regurgitation (5%). Perioperative myocardial infarction was predicted by the extent of coronary artery disease. The incidence of perioperative myocardial infarction was higher in patients with triple-vessel coronary artery disease (13%) and those with left main stenosis (18%) than in patients with single- or double-vessel disease (4%) or those without coronary artery disease (4%). Because of the higher risk of aortic valve replacement in older patients, the risk-benefit ratio of the operation must be carefully assessed in the elderly. Improved methods of myocardial protection may reduce the risks for patients with aortic stenosis and symptomatic triple-vessel coronary artery disease.

Early and late risk of aortic valve replacement. A 12 year concomitant comparison of the porcine bioprosthetic and tilting disc prosthetic aortic valves.

Aortic valve replacement was performed in 912 consecutive patients from January, 1972, to January, 1983. The 616 male and 296 female patients, whose ages ranged from 16 to 95 years (mean 60.6 years and median 63 years), received 663 bioprosthetic valves and 249 tilting disc valves. A higher incidence of Functional Class IV heart disease and ascending aortic aneurysms was noted in the group receiving the tilting disc valve. Six hundred fifty-seven patients had primarily aortic stenosis and 255 had primarily aortic regurgitation. Associated procedures were done in 308 patients (33%): 233 had coronary bypass grafting, 46 had replacement of ascending aortic aneurysms, and 29 had miscellaneous procedures. The overall operative mortality was 6.4% (59/912). The operative mortality was 4.5% (29/640) for isolated aortic valve replacement, 4.2% (21/233) for valve replacement plus coronary bypass, and 17% (8/46) for valve replacement plus replacement of an ascending aortic aneurysm. The mortality was 4.2% (20/663) for the group receiving bioprostheses and 12.4% (31/249) for those receiving tilting disc valves. The operative mortality for 1983 for all aortic valve replacement procedures was 2.1%; for isolated valve replacement, 1%; for valve replacement plus coronary bypass, 4.4%; and for valve replacement plus aortic aneurysm replacement, 0%. The long-term follow-up was analyzed as of Jan. 1, 1984, so that there was a minimum follow-up of 12 months (mean 55 months and median 51 months). The actuarial survival rate at 108 months for all patients was 67% +/- 2%; for valve replacement alone, 71% +/- 3%; for valve replacement plus coronary bypass, 58% +/- 7%; for valve replacement plus ascending aortic aneurysm replacement, 45% +/- 10%; for aortic stenosis, 70% +/- 3%; for aortic regurgitation, 61% +/- 4%; for Functional Classes I to III, 77% +/- 3%; for Class IV, 53% +/- 4%; for age less than 63 years, 75% +/- 3%; and for age greater than 63 years, 57% +/- 4%. At 108 months, the probability of freedom from thromboembolism was 85% +/- 3% after bioprosthetic valve replacement and 83% +/- 3% after replacement with a tilting disc valve (p = NS). The probability of freedom from hemorrhage at 108 months was 98.6% +/- 7% for the bioprosthetic valve group and 89% +/- 2% for the tilting disc valve group (p less than 0.001). The valve thrombosis rate was 0.34% per patient-year for the tilting disc valves and 0.07% per patient-year for the bioprostheses.(ABSTRACT TRUNCATED AT 400 WORDS)

Five-year evaluation of the Carpentier-Edwards porcine bioprosthesis.

The Carpentier-Edwards porcine bioprosthesis compares favorably to other value substitutes, with a low incidence of valve-related complications after up to 6 years' follow-up. From April, 1976, to February, 1978, 397 prostheses were implanted in 355 patients at the University of British Columbia and the Montreal Heart Institute: aortic valve replacement (AVR), 155; mitral valve replacement (MVR), 154; tricuspid valve replacement (TVR), five; multiple replacement (MR), 41 patients. Previous cardiac operations had been performed in 58 patients (16.3%). Concomitant cardiac procedures, including myocardial revascularization, were performed in 66 patients (18.5%). The 30 day mortality was 8.7% (31 patients (AVR, 4.5%; MVR 9.0%; TVR 20%; MR 21.9%). The cumulative follow-up was 1,367 patient-years (range 6 to 81 months, mean 51 months). The late mortality is 3.9% per patient-year (AVR 3.4%, MVR 3.6%, MR 6.3%). The long-term valve-related complication rates (expressed as percent per patient-year and number of events) are as follows; thromboembolism (AVR 1.1 [seven], MVR 1.7 [10], MR 3.2 [four]; prosthetic valve endocarditis (AVR 0.6 [four], MVR 0.3 [two], MR 1.6 [two]); primary tissue failure (AVR 0.16 [one], MVR 1.0 [six], MR 1.6 [two]); anticoagulant-related hemorrhage 0.07 (one); and reoperation (AVR 0.48 [three], MVR 1.32 [eight], MR 2.4 [three]). Actuarial survival rates at 6 years, including operative deaths, are as follows: AVR 81.4% +/- 5.6%, MVR 70.0% +/- 6.7%, and MR 52.1% +/- 12.5%. The overall survival rate was 74.0% +/- 4.5% at 6 years. The freedom from all valve-related complications at 72 months was 83.9% +/- 4.8%. The freedom from valve-related death was 97.3% +/- 1.8% at 72 months. The freedom from valve-related death and reoperation at 72 months was 91.5% +/- 3.8%, and the freedom from reoperation alone was 93.4% +/- 3.5%. There were no deaths due to reoperation for primary tissue failure. Performance to date with the Carpentier-Edwards porcine bioprosthesis has been excellent, with an evaluation interval extending from 60 to 81 months.

Long-term clinical and hemodynamic evaluation of the Ionescu-Schiley pericardial xenograft and the Braunwald-Cutter and Björk-Shiley prostheses in the mitral position.

Single mitral valve replacement was undertaken in 220 patients between March, 1971, and October, 1977. Bjork-Shiley prostheses (BS) were inserted in 42 patients, Braunwald-Cutter prostheses (BC) in 52, and Ionescu-Shiley pericardial xenografts (PX) in 126. No attempt was made at randomization. The actuarial survival rate was 81.9 +/- 12.8 percent at 7 years for patients with BS prostheses, 41.7 +/- 22.9 percent at 6 years for patients with BC prostheses, and 89.0 +/- 9.3 percent for patients with PX valves 7 years following valve replacement. Of the late deaths in patients with BC prostheses, 62.5 percent were valve related. The incidence of thromboembolism was 4.7, 1.8, and 1.5 episodes per 100 patient-years in the BS, BC, and PX groups, respectively. Long-term anticoagulation was used only in patients with BS and BC prostheses. Late postoperative hemodynamic studies were performed in six patients each with BS and BC prostheses and in 29 patients with PX valves. The mean diastolic gradients at rest were 6.2, 8.3, and 6.4 mm. Hg in the respective groups. The corresponding figures for calculated valve area were 1.8, 1.6, and 2.0 sq. cm. There was no statistically significant difference between the data recorded from the three groups of patients except for the survival rate of the BC prosthesis and the PX valve. The BS prosthesis and the PX valve have similar durability and hemodynamic performance for an almost identical duration of follow-up. Because of the improved quality of life and reduced morbidity without anticoagulants, we are using the PX valve exclusively for heart valve replacement.

Aortic valve replacement with a stentless porcine aortic valve. A six-year experience.

A stentless porcine aortic valve was used for aortic valve replacement in 123 patients from 1987 to 1993. The mean age of 86 men and 37 women was 61 +/- 12 years. Most patients had aortic stenosis; one-third had coronary artery disease and six had mitral valve disease. The stentless valve was secured in the subcoronary position by the same technique used for a freehand aortic valve homograft. The size of valve was based largely on the diameter of the sinotubular junction of the aortic root. The mean valve size was 26.5 mm (range 19 to 29 mm) and 87% were 25 mm or larger. Two operative deaths occurred, one the result of myocardial infarction and the other the result of infective endocarditis. Patients have been followed up from 3 to 77 months, mean 22 months. Three late deaths, none related to the valve, have occurred. The actuarial survival at 6 years was 91% +/- 4%. Four transient cerebral ischemic events have occurred, but two patients had extracranial cerebrovascular disease. One patient had endocarditis late in the postoperative period and required reoperation. All patients had Doppler echocardiographic studies before discharge from the hospital, 3 to 6 months later and annually. Only 15 patients have aortic insufficiency, trivial in 6 and mild in 9. The peak and mean systolic gradients decreased significantly during the first 3 to 6 months after implantation (p < 0.001), and the effective valve areas increased significantly during this time interval (p < 0.001). This improvement in valve hemodynamics is believed to be due to remodeling of the aortic root and regression of left ventricular hypertrophy. The results of aortic valve replacement with this stentless bioprosthesis have been excellent and justify its continued use in older patients.