Late incidence and determinants of reoperation in patients with prosthetic heart valves.

OBJECTIVES: Reoperation is a relatively common event in patients with prosthetic heart valves, but its actual occurrence can vary widely from one patient to another. With a focus on bioprosthetic valves, this study examines risk factors for reoperation in a large patient cohort. METHODS: Patients (N=3233) who underwent a total of 3633 operations for aortic (AVR) or mitral valve replacement (MVR) between 1970 and 2002 were prospectively followed (total 21,179 patient-years; mean 6.6+/-5.0 years; maximum 32.4 years). The incidence of prosthetic valve reoperation and the impact of patient- and valve-related variables were determined with actual and actuarial methods. RESULTS: Fifteen-year actual freedom from all-cause reoperation was 94.1% for aortic mechanical valves, 61.4% for aortic bioprosthetic valves, 94.8% for mitral mechanical valves, and 63.3% for mitral bioprosthetic valves. In both aortic and mitral positions, current bioprosthesis models had significantly better durability than discontinued bioprostheses (15-year reoperation odds-ratio 0.11+/-0.04; P<0.01 for aortic, and 0.42+/-0.14; P=0.009 for mitral). Current bioprostheses were significantly more durable in the aortic position than in the mitral position (14.3+/-6.8% more freedom from 15-year reoperation; (P=0.018)). Older age was protective, but smoking was an independent risk factor for reoperation after bioprosthetic AVR and MVR (hazard ratio for smoking 2.58 and 1.78, respectively). In patients with aortic bioprostheses, persistent left ventricular hypertrophy at follow-up and smaller prosthesis size predicted an increased incidence of reoperation, while this was not observed in patients with mitral bioprostheses. CONCLUSIONS: These analyses indicate that current bioprostheses have significantly better durability than discontinued bioprostheses, reveal a detrimental impact for smoking after AVR and MVR, and indicate an increased reoperation risk in patients with a small aortic bioprosthesis or with persistent left ventricular hypertrophy after AVR.     

Late incidence and determinants of stroke after aortic and mitral valve replacement

Background

Stroke is a devastating complication in patients with prosthetic valves, but characterization of its late occurrence from a large cohort is lacking.

Methods

Three thousand one hundred eighty-nine adult patients who underwent a total of 3,576 operations for left-heart valve replacement were managed with contemporary anticoagulation guidelines and prospectively followed in a dedicated clinic. Total follow-up was 20,096 patient years. Bootstrapped survival analysis was used to determine the impact of patient and valve related factors on the incidence of stroke.

Results

Most strokes were embolic. Linearized embolic stroke rates were 1.3% ± 0.2% per year for aortic bioprostheses, 1.4% ± 0.2% per year for aortic mechanical valves, 1.3% ± 0.3% per year for mitral bioprostheses, and 2.3% ± 0.4% per year for mitral mechanical valves (p = 0.002, vs other implant types). Age more than 75 years, female gender, and smoking were independent risk factors after aortic and mitral valve replacement. Atrial fibrillation, coronary disease, and tilting-disc mechanical prostheses were independent predictors of embolic stroke after aortic valve replacement. Preoperative left ventricular (LV) dysfunction was an independent risk factor in patients with mitral prostheses. Primary operative indication, diabetes, redo status, or the presence of two prosthetic valves were not associated with an increased hazard. The addition of acetyl salicylic or dipyridamole to warfarin anticoagulation did not significantly lower embolic stroke risk in patients with mechanical prostheses.

Conclusions

Approximately 20% of patients with valve prostheses have an embolic stroke by 15 years after valve replacement. Some risk factors such as the avoidance of smoking, mitral mechanical prostheses, aortic tilting-disc valves, and proceeding to mitral surgery before LV dysfunction occurs are potentially modifiable.     

Preliminary Experience with Aspirin for Anticoagulation in Children with Prosthetic Cardiac Valves

Twenty-four children (ages 1 to 18 years, mean 12.2 years) underwent 27 operations for aortic, mitral, or combined aortic and mitral valve replacement. There was 1 operative death. Of the 23 operative survivors (12 aortic, 8 mitral, 3 combined valve replacement), only 5 were given warfarin for long-term anticoagulation. The remaining 18 (10 aortic, 8 mitral valve replacement) were given aspirin (plus dipyridamole in 5). Twelve of the 18 had at least one mechanical valve (11 Björk-Shiley and Beall valves; 1 Björk-Shiley valve was replaced with a Beall disc valve as the child grew).These 18 patients were followed for 1 to 59 months (mean, 20.4 months). There was no thrombotic, embolic, or bleeding complications. There were 2 late deaths (one cardiac).Review of the available literature indicates that in children with prosthetic cardiac valves, aspirin (with or without dipyridamole) provides adequate protection against thromboemboli and avoids the hemorrhagic complications associated with warfarin.     

Thromboembolic Complications of Current Cardiac Valvular Prostheses

Thromboembolic complications associated with twelve different models of currently available aortic and mitral valve prostheses are reviewed. There is a need to standardize definitions of thrombotic phenomena and to report these events for valve model and anatomic location actuarially and in terms of incidence per 100 patient-years of follow-up. The incidence of thromboemboli is less than 2 per 100 patient-years for aortic biological valves without coumarin anticoagulation and for the best mechanical valves with coumarin. For mitral biological prostheses with and without coumarin, and for the best mechanical mitral valves with coumarin, the incidence approximates 4 per 100 patient years. The incidence of mortality and morbidity due to coumarin anticoagulation in patients with prosthetic valves is 0.17 and 2.2 per 100 patient-years, respectively. Omission, poor control or withdrawal of coumarin anticoagulation substantially increases the incidence of thromboemboli in patients with mechanical valves. Some reports suggest that the combination of dipyridamole and coumarin may further reduce thromboembolic complications without increasing bleeding problems. Atrial fibrillation clearly increases thromboembolic complications, but the importance of other factors such as atrial clot, large left atrial size, history of emboli, and first postoperative year is less definite.     

Comparison of outcomes after mitral valve replacement with a mechanical versus a bioprosthetic valve in patients between forty and sixty years of age

Background  The American College of Cardiology/American Heart Association (ACC/AHA), guidelines for choice of prosthetic valve based on patients’ age are difficult to apply to the developing world because of a lower life expectancy and difficulty in maintaining correct levels of anticoagulation for a variety of reasons. While there is general agreement on the choice of prosthetic valves for patients below 40 years of age (mechanical) and above 60 years of age (biologic), the 40 to 60 age group remains a grey zone. The goal of our study was to compare outcomes after mitral valve replacement with a mechanical versus a bioprosthetic valve in patients between forty and sixty years of age. Methods  From Jan 2003 to July 2008, 250 patients between the ages of 40 and 60, undergoing mitral valve replacement at our institution were randomized to receive either a mechanical or a bioprosthetic valve. Outcomes in the form of incidence of valve thrombosis and thromboembolism, bleeding complications, incidence of prosthetic valve endocarditis and survival were compared in the two groups. Results  Out of 250 patients, 135 patients received mechanical valve and 115 patients were implanted with a bioprosthetic valve. Patients were followed up for a mean period of 3 years (range 6 months to 4.8 years). The incidence of valve thrombosis was higher in mechanical valve as compared to bioprosthetic valve (6% vs. 0.9%, p= 0.04). Similarly there was a higher incidence of thromboembolism in mechanical valves as compared to bioprosthetic valves (4.5% vs. 0%, p=0.03). Bleeding complications occurred more frequently in mechanical than bioprosthetic valve (6% vs. 0.9%, p=0.04). There was no significant difference in the incidence of prosthetic valve endocarditis (2.2% vs. 2.7%, p >0.05) or survival at three years (96.2% vs. 97.2%, p > 0.05) in the two groups. Conclusions  Patients in the age group of 40 to 60 years undergoing mitral valve replacement with a mechanical valve have a higher incidence of thrombotic and bleeding complications as compared to bioprosthetic valve, even though short term survival is similar. This favours implantation of a bioprosthetic valve in this age group.     

Age-related complications and optimal choice of artificial heart valves in elderly patients

The use of bioprosthetic heart valves in elderly patients is presently advocated by many since implanting mechanical valves are considered to result in unacceptable rates of thromboembolism and bleeding. However the somewhat limited durability of bioprostheses has to be acknowledged since a group of elderly patients will eventually require a reoperation due to tissue failure. We have evaluated our policy to implant mechanical heart valve prostheses even in elderly patients based on the conception that we believe that anticoagulation in this group of patients can be handled with a low rate of complications.     

Cardiac valve replacement in patients on dialysis: influence of prosthesis on survival

BACKGROUND: Mechanical valves have been recommended for patients on dialysis because of purported accelerated bioprosthesis degeneration. This study was undertaken to determine time-related outcomes in dialysis patients requiring cardiac valve replacement. METHODS: From 1986 to 1998, 42 patients on chronic preoperative dialysis underwent valve replacement; 17 received mechanical valves and 25 received bioprostheses. Age was similar in both groups: 54+/-18.5 years (mechanical) and 59+/-15.5 years (bioprosthetic, p = 0.4). Sites of valve replacement were aortic (27), mitral (11), and aortic and mitral (4). Follow-up was 100% complete. RESULTS: Survival at 3 and 5 years was 50% and 33% after mechanical valve replacement, and 36% and 27% after bioprosthetic valve replacement (p = 0.3). Four patients with bioprostheses required reoperation: 3 for allograft endocarditis and 1 at 10 months for mitral bioprosthesis degeneration. One patient who received a mechanical valve required reoperation. CONCLUSIONS: Prosthetic valve-related complications in patients on dialysis were similar for both mechanical and bioprosthetic valves. Because of the limited life expectancy of patients on dialysis, bioprosthesis degeneration will be uncommon. Therefore, surgeons should not hesitate to implant bioprosthetic valves in these patients.     

Cardiac Valve Prostheses: Pathological and Bioengineering Considerations

Cardiac valve replacement with mechanical prosthetic or bioprosthetic devices enhances patient survival and quality of life. Nevertheless, prosthesis-associated complications are frequent and contribute significantly to outcome. Thrombo-embolic complications are the most important problems in patients with mechanical valves, necessitating chronic anticoagulation in all patients receiving them. In contrast, patients with bioprosthetic valves, composed of chemically treated animal tissues, generally do not require anticoagulants. However, bioprostheses fail frequently by degeneration, especially that involving cuspal calcification. This paper reviews the pathological and bioengineering considerations in the selection of cardiac prosthetic valves and the management of patients who have received these devices. The significance, morphology, and pathogenesis of the observed major complications and other alterations during function are described in detail. Contemporary investigative trends are summarized, including studies of inhibition of mineralization and other degenerative changes in bioprostheses, improved design rigid mechanical valves with pyrolytic carbon occluders and the development of central-flow, flexible polymeric leaflet valves.     

Mitral valve replacement in the first 5 years of life

Between 1976 and 1986, 19 children aged 1 month to 5 years underwent replacement of the mitral (systemic atrioventricular) valve. Indications for valve replacement included isolated congenital mitral stenosis (n = 2), valve dysfunction associated with a more complex procedure (n = 15), and failed valvuloplasty (n = 2). Seven different valve types were used; nine were mechanical valves and ten were bioprosthetic valves. There were 6 hospital deaths (32%; 70% confidence limits, 20% to 47%). Among the 13 survivors there were 3 late deaths at a mean of 14 months after operation. The late deaths were unrelated to valve malfunction. Thromboembolic events occurred in 2 patients, both with mechanical valves. One minor bleeding complication occurred among 10 patients on a regimen of Coumadin (crystalline warfarin sodium). Five patients, all with bioprostheses, required a second valve replacement. Indications for reoperation included prosthetic valve regurgitation (n = 1) and calcific stenosis (n = 4). No early or late deaths occurred after second valve replacement. Survival was 51% +/- 12% (standard error) at 112 months after valve replacement. Analysis failed to identify age, weight, sex, previous operation, underlying cardiac lesion, or prosthesis size and type as significant risk factors for mortality. Mechanical valves had a lower reoperation rate compared with bioprostheses. These data suggest that although mitral valve replacement within the first 5 years of life is associated with a high operative and late mortality, satisfactory long-term palliation for many patients can be achieved. Mechanical valves are superior to bioprosthetic valves, and offer the best long-term results.     

Acute thrombotic obstruction with Bj?rk-Shiley valves: diagnostic and surgical considerations

Eight patients have had thrombotic obstruction of a prosthetic valve since 1971, six mitral valves and two aortic. All eight patients had a Bj?rk-Shiley valve. During the same period 159 Bj?rk-Shiley valves were placed, 85 in the mitral and 74 in the aortic area. This represents a valve thrombotic occlusive incidence of 4.4 percent in our series, 5.9 percent of mitral and 2.7 percent of aortic prostheses. Among the six patients with mitral prostheses only one survived. The two patients with occluded aortic valves survived. The onset of symptoms was very abrupt in most patients and progressed very rapidly. Acute pulmonary edema was observed in five patients. Anticoagulation was considered inadequate in all patients. Aspirin or dipyridamole was being used in seven patients at the time of thrombosis. The data indicate a high frequency of thrombotic occlusion of Bj?rk-Shiley valves in the absence of full anticoagulation with warfarin derivatives and emphasizes the urgent need for surgery once valve thrombosis is suspected.     

Simultaneous implantation of St. Jude Medical aortic and mitral prostheses

Since January 1980, 92 consecutive patients received St. Jude Medical aortic and mitral prostheses simultaneously. Mean age was 57.6 years (standard deviation 12.4); 14 were 70 years or older. Twenty-three had a previous cardiac operation and 22 had additional procedures performed at the time of double valve replacement. Before the operation 62% of the patients were in New York Heart Association functional class III and 29% were in class IV or required emergency operation. There were six (6.5%) deaths within 30 days. None of the hospital deaths were valve related; all occurred in patients who had additional risk concerns. Follow-up is 100% complete and ranges from 2 to 80 months, totaling 242 patient-years (mean 33.8 months). All except four hospital survivors reached class I or II and 40 patients (47%) remain asymptomatic. The actuarial survival rates are 82% at 1 year, 70% at 3 years, and 60% at 5 years. Causes of late death include heart failure (10), sudden, unexplained death (five), reoperation for coronary artery disease (one), noncardiac (four), and valve related (five). The linearized rate of fatal valve-related events is 2.1% pt-yr. A total of 22 valve-related complications (including five fatal) occurred is 18 patients, for a linearized rate or incidence of 9.1%/pt-yr. Eleven thromboembolic episodes (rate 4.6%/pt-yr) occurred in nine patients; three of these (1.2%/pt-yr) were fatal. Thromboembolic and bleeding complications represented 64% of all valve-related complications. Four patients had six episodes of prosthetic valve endocarditis (incidence 2.5%/pt-yr), of which one (incidence 0.4%/pt-yr) was fatal. Paravalvular leak contributed to the fifth valve-related death. At 5 years, 83% of patients were free of thromboembolic complications; 94% were free of anticoagulant-related hemorrhage; and 71% were free of all valve-related complications. There are few comparable data for patients who have had simultaneous replacement of aortic and mitral valves with other mechanical prostheses. The total incidence of valve-related complications for patients with bioprostheses ranges between 3.9%/pt-yr and 10.4%/pt-yr and is similar to the 9.1%/pt-yr observed in the present series. The type of valve-related complication (thromboemboli and bleeding versus valve deterioration) is the principal difference between St. Jude Medical and bioprosthetic valves in patients who require simultaneous replacement of aortic and mitral valves.     

LVAD support in patients with bioprosthetic valves

The presence of mechanical or bioprosthetic valves has traditionally excluded patients from mechanical circulatory support. However, several centers have now developed algorithms for the surgical management of native or prosthetic valve disease in patients requiring left ventricular assist device insertion. We report adverse events associated with bioprosthetic valves in the mitral and tricuspid positions in 2 patients who received long-term mechanical support. We recommend anticoagulation for all patients with prosthetic valves in the mitral or tricuspid position to avoid thromboembolism, inflow conduit occlusion, or valvular incompetence.     

Ventricular assist device in patients with prosthetic heart valves

Ventricular assist device (VAD) support inpatients with a prosthetic heart valve had previously been considered a relative contraindication due to an increased risk of thromboembolic complications. We report our clinical experience of VAD implantation in patients with prosthetic heart valves, including both mechanical and bioprosthetic valves. The clinical records of 133 consecutive patients who underwent VAD implantation at a single institution from January 2002 through June 2009 were retrospectively reviewed. Six of these patients had a prosthetic valve in place at the time of device implantation. Patient demographics,operative characteristics, and postoperative complications were reviewed.Of the six patients,four were male.The mean age was 57.8 years (range 35–66 years). The various prosthetic cardiac valves included a mechanical aortic valve (n = 2), a bioprosthetic aortic valve (n = 3), and a mechanical mitral valve (n = 1).The indications for VAD support included bridge to transplantation (n = 2), bridge to recovery (n = 1), and postcardiotomy ventricular failure(n = 3). Three patients underwent left ventricular assist device placement and three received a right ventricular assist device. Postoperatively, standard anticoagulation management began with a heparin infusion (if possible)followed by oral anticoagulation.The 30-day mortality was50% (3/6). The mean duration of support among survivors was 194.3 days (range 7–369 days) compared with 16.0 days(range 4–29 days) for nonsurvivors. Of the three survivors,two were successfully bridged to heart transplantation and one recovered native ventricular function.Among the three nonsurvivors,acute renal failure developed in each case, and two developed heparin-induced thrombocytopenia. This study suggests that VAD placement in patients with a prosthethic heart valve, either mechanical or bioprosthetic,appears to be a reasonable option.     

Thromboembolic and bleeding complications in patients treated with oral anticoagulant therapy after mechanical heart valve prostheses implantation

Thromboembolic and bleeding events are major cause of morbidity and mortality in patients with mechanical heart valves. Ninety-three patients had been received anticoagulant (warfarin with bucolome 300 mg) for mechanical prosthetic valves, and the regulation of anticoagulation was performed within a prothrombin time international normalized ratio (PT-INR) about 2.0 of normal. The mean duration of follow-up was 64.1 months, and the total duration of follow-up was 496.8 patient-years (py). The valve related complications occurred in 10 cases (2.0 per 100 py). Anticoagulant related hemorrhagic events occurred in 7 cases, and valve thrombosis in 3 cases. All three cases of valve thrombosis were in cases with Bj?rk-Shiley valve at the mitral position. An artificial valve in mitral position increased the valve related risk compared with the aortic position (3.1%/py vs 0.0%/py). Bileaflet valve showed a lower incidence of thromboembolism than tilting disc valve (2.3%/py vs 0.0%/py). The risk of valve related complication varied with the type and the position of the prosthesis, it is desirable that the intensity of anticoagulation would be changed according to the prosthetic valve type and its position. These results suggest that the intensity of anticoagulation is optimal when the PT-INR is 1.8-2.0 for patients with bileaflet valve in the mitral position, and is 1.6-1.8 in the aortic position. Tilting disc valve needs more intensity of anticoagulation, and needs additional antiplatelet agent in the mitral position.     

Long-term results of porcine bioprosthetic heterograft; a 13-years' experience

One hundred and ninety-four patients underwent valve replacements with the glutaraldehyde-preserved porcine bioprostheses (133 Hancock valves, 39 Angell-Shiley valves, 22 Carpentier-Edwards valves and 3 other valves) from 1974 through 1979. There were 105 women and 89 men, whose age ranged 18 to 62 (mean 38.8) years. One hundred and eighty-two patients had mitral bioprosthetic valve replacement (BVR)s, of which 52 had combined aortic mechanical valve replacements, 8 had aortic BVR's, 3 had tricuspid BVR's and 3 had multi-BVR's. Operative mortality was 10.8%. Only one patient was lost to follow-up. Cumulative duration of follow-up is 1421 patient-years. Linearized rate of anticoagulant related hemorrhage, thromboembolism (TE), prosthetic valve endocarditis (PVE), primary tissue failure (PTF) and valve dysfunction (VD) were 0.07, 1.62, 0.49, 2.74 and 3.66% per patient-year. Actuarial freedom from TE, PVE, PTF and VD were 87.0 +/- 2.7%, 95.6 +/- 1.5%, 65.2 +/- 4.9% and 56.9 +/- 5.6% at 13 years. Actuarial survival rate was 67.4 +/- 4.0% at 13 years. Long term follow-up after valve replacement with porcine bioprosthetic valve confirms low thrombogenicity. But primary tissue failure was the chief cause of valve dysfunction and represent a major problem. At this time, we are going to use porcine bioprosthetic valve in the selected patients, that is in the situations in which anticoagulation is contraindicated.     

Mitral Valve Replacement with the Hancock Bioprosthesis: Five- to Ten-Year Follow-up

One hundred eleven patients undergoing mitral valve replacement, either alone (56) or in conjunction with another type of prosthetic valve, prior to 1975 were evaluated. Hospital mortality was 9.9%. Cumulative follow-up is 505 patient-years (mean, 5.4 years). Seventy patients have been followed between 5 and 10 years. Late mortality for mitral valve replacement alone is 4.3 ± 1.3% per patient-year; actuarial survival is 82 ± 6% at 5 years and 65 ± 11% at 10 years. The incidence of emboli was 3.3 ± 0.9% per patient-year for all patients with bioprostheses (62) and 4.2 ± 1.7% per patient-year for bioprostheses and concomitant mechanical aortic valves (32). In patients with only bioprostheses, two of twelve emboli occurred within the first 6 postoperative months and there were three fatal cerebral emboli (0.8 + 0.5% per patient-year). The incidence of hemorrhagic complications is 4.9 ± 1.9% for anticoagulated patients with bioprostheses and mechanical aortic valves; one hemorrhage was fatal (0.7 ± 0.7% per patient-year). Intrinsic mitral bioprosthesis failure occurred in 10 patients; 2 died. Five patients had valve failure secondary to perivalvular regurgitation (3) or endocarditis (2). Actuarial late survival free from intrinsic mitral bioprosthetic failure was 99 ± 1% at 5 years, 92 ± 4% at 7 years, 70 ± 12% at 9 years, and 61 ± 13% at 10 years.It is unknown at the present time whether the long-term risk of late intrinsic valve failure and reoperation will outweigh the low incidence of emboli and avoidance of anticoagulant-related hemorrhage. Until further information becomes available, the Hancock bioprosthesis is used for mitral valve replacement only in patients older than 60 years or in patients with contraindications for anticoagulant therapy.     

Discrepancies Between Labeled and Actual Dimensions of Prosthetic Valves and Sizers

A bstract Background and aims : The hemodynamic performance of a mechanical or stented bioprosthetic valve is primarily determined by the diameter of its orifice. Thus, in aortic or mitral valve replacement, assessment of the native annular size and selection of the correspondingly sized prosthetic valve is necessary to achieve maximum hemodynamic performance. The purpose of this study was to determine the actual dimensions of aortic and mitral valve sizers and their corresponding prostheses, and to determine whether they differed from their marked dimensions. Methods : Mechanical and stented bioprosthetic valves and sizers were obtained from the manufacturers (CarboMedics, St. Jude, Medtronic-Hall, Starr-Edwards, Carpentier-Edwards, and Medtronic-Hancock), and the diameters were measured. Results : For the mechanical models, both aortic and mitral sizers were larger than their marked size by 0.5 mm to 1.0 mm. The aortic valves were all smaller than their corresponding sizers, but the relationship of the mitral valves to corresponding sizers varied with the manufacturer. For the bioprosthetic models the aortic and mitral sizers were true to marked size, the aortic valves were close to marked size and the mitral valves were smaller than marked size. Conclusions : These differences make optimal sizing difficult at best, particularly if more than one manufacturers' product is used in an institution. These differences may or may not impact valve performance in an individual surgeon's hands. However, the wide range of variations across prosthetic type and manufacturer obligate the surgeon to be aware of these variances to achieve maximum hemodynamic performance for each patient.     

Ventricular assist device support in patients with mechanical heart valves

Background. Due to potential thromboembolic complications, mechanical valves within the native heart are often considered contraindications to ventricular assist device (VAD) support.

Methods. A retrospective review of VAD cases between June 1982 and March 1998 showed 8 patients with mechanical valves who were supported with Thoratec (Pleasanton, CA) VADs.

Results. There were 6 males and 2 females ranging in age from 20 to 69 years (mean 49.8 ± 5.6). Four patients were supported when they could not be weaned from cardiopulmonary bypass after reparative procedures and were thought to have reversible injuries. Four patients were supported as a bridge-to-cardiac transplantation. Two patients had mechanical mitral valves, 2 had aortic valve replacements, 1 had an aortic homograft and mechanical mitral valve, 2 had mechanical aortic and mitral prosthesis, and 1 patient had aortic, mitral, and triscupid valves. The types of valvular prostheses were St. Jude (5 patients) and Bjork-Shiley (3 patients). Duration of support ranged from 3.0 to 150 days (mean 34 days). Four patients were supported with biventricular assist devices and 4 had left VADs. Dextran and intravenous heparin anticoagulation were used in the shorter duration patients, with warfarin being used in the bridge patients. One patient received warfarin and aspirin. At the time of autopsy or device removal, only 1 of the 12 mechanical intracardiac valves showed any evidence of thrombosis, including the aortic valves in 2 patients supported for 2 and 5 months. There were no clinical thromboembolic events. Four patients (50%) were discharged (1 weaned, 3 transplanted).

Conclusions. The 50% (4 of 8) survival rate compares favorably with the 44% (41 of 92) overall survival rate for our Thoratec patients (bridge plus recovery) who did not have mechanical prosthetic valves. These data suggest that patients with mechanical intracardiac valves can be supported for short durations with some additional risk, which is yet to be determined.     

An eight-year experience with porcine bioprosthetic cardiac valves

A total of 589 porcine bioprostheses were implanted in 509 patients from January, 1976, through December, 1983. Of the valves implanted, 390 were Hancock and 199 were Carpentier-Edwards. A total of 1,633 patient-years was accrued, with a mean follow-up of 38 months per patient. Two hundred eight patients had aortic valve replacement, 209 had mitral valve replacement, and 79 had multiple valve replacements, of which 46 were aortic and mitral replacements. The mortality for isolated aortic valve replacement was 5.8%; for isolated mitral replacement, 8.6%, and for all patients, 10.9%. Late mortality was 3.9% per patient-year. The actuarial survival rate at 5 years was 79% for aortic, 68% for mitral, and 76% for aortic-mitral valve replacement. There were 12 thromboembolic events (0.73% per patient-year). Two episodes occurred in patients with an aortic bioprosthesis, nine in patients with a porcine mitral valve, and one in a patient with mitral and tricuspid bioprosthetic valves. The probability of remaining free of thromboembolism at 5 years was 99% for the group having aortic valve replacement, 93% for those having mitral replacement, and 100% for the group having aortic-mitral valve replacements. Thirteen episodes of endocarditis occurred (0.8% per patient-year). Seven of the 13 patients died as a direct result of endocarditis. The probability of remaining free of prosthetic endocarditis at 5 years was 97% for the aortic valve replacement group, 95% for the mitral group, and 97% for the aortic-mitral group. There were 20 instances of xenograft failure (1.2% per patient-year). The probability of remaining free of valve failure at 5 years was 96% for the aortic valve replacement group, 93% for the mitral group, and 93% for the aortic-mitral replacement group. Primary tissue failure of a prosthesis occurred in seven patients, all with Hancock valves (0.43% per patient-year). As yet there has been no primary tissue failure of the Carpentier-Edwards prosthesis. There also appears to be a lower incidence of thromboembolism (Edwards, 0.3% per patient-year; Hancock, 0.8% per patient-year) and endocarditis (Edwards, 0.6% per patient-year; Hancock, 1.0% per patient-year). The low incidence of complications with the porcine bioprosthetic valve, especially the Carpentier-Edwards, encourages us to recommend its continued use, especially in situations in which anticoagulation is contraindicated.     

Acute endocarditis treated with radical debridement and implantation of mechanical or stented bioprosthetic devices

BACKGROUND: Operation for active infective endocarditis carries high mortality and morbidity rates, especially when the annulus is involved. Overall the literature favors the use of autograft and homograft valves because of better resistance to infection. In our clinic during the last 5 years we used an aggressive surgical approach to infective endocarditis in combination with implantation of mechanical or stented bioprosthetic devices. METHODS: From 1994 to 1999, 50 adults with aortic and/or mitral valve endocarditis underwent valve replacement. The median age of the 36 men and 14 women was 58 years (range, 17 to 78 years). All patients had active endocarditis at the time of operation. Native valve endocarditis was present in 48 patients and prosthetic valve endocarditis was present in 2 patients. The aortic valve was affected in 24 patients, the mitral valve in 21 patients, and both the aortic and mitral valves in 5 patients. Two of the patients with mitral endocarditis also had infection of the tricuspid valve. Annular destruction was present in 24 patients (48%). The patients were treated with radical excision of all infected tissue. The annular defects were closed, if possible, with direct sutures. Otherwise, a reconstruction was performed. Follow-up was 100% complete with a median follow-up period of 45 months (range, 6 to 66 months). RESULTS: The procedures were performed without lethal bleeding complications. Early mortality was 12% and the actuarial survival at follow-up was 80%. In none of the patients who died was death related to the prosthetic valve or recurrence of the endocarditis. Only 1 patient (2%) developed recurrence of the infective endocarditis and was reoperated with a Ross procedure. Three and a half years later the patient developed severe valve insufficiency of the autograft and was operated again with implantation of a mechanical device. CONCLUSIONS: Native and prosthetic valve endocarditis can be treated successfully with aggressive surgical debridement and implantation of mechanical or stented bioprosthetic devices with a low risk of recurrent endocarditis.