Francisco Guerra

Performance of the Hancock Porcine Bioprosthesis Following Aortic Valve Replacement: Considerations Based on a 15-Year Experience

All patients undergoing isolated aortic valve replacement with a standard Hancock porcine bioprosthesis (PB), from 1970 to 1983, were reviewed. There were 196 patients, 162 male and 34 female patients, with a mean age of 48 +/- 12 years. Operative survivors were followed up from 3 to 15.6 years (mean follow-up, 6.6 +/- 1.5 years), with a cumulative follow-up of 1,140 patient-years, being 100% complete. Actuarial survival was 51 +/- 15% at 14 years. Eight patients sustained systemic embolic episodes (0.7 +/- 0.2%/patient-year); actuarial freedom from emboli is 89.4 +/- 4.3% at 14 years. Reoperation was performed in 53 patients: in 6 because of endocarditis (0.5 +/- 0.2%/patient-year), in 7 because of perivalvular leak (0.6 +/- 0.2%/patient-year), and in 40 because of PB primary tissue failure (3.5 +/- 0.5%/patient-year). Actuarial freedom from PB-related deaths, PB failure, and overall PB-related complications at 14 years was 66.3 +/- 19, 34.3 +/- 11, and 30 +/- 10%, respectively. This long-term experience shows that the performance of the Hancock PB appears satisfactory up to 8 years, while it progressively deteriorates beyond 10 years because of the impact of primary tissue failure on valve durability, justifying the restriction of its use in the aortic position in selected patients.

The standard Hancock porcine bioprosthesis: overall experience at the University of Padova

All patients undergoing aortic (AVR, n = 196), mitral (MVR, n = 502), and mitralaortic (MAVR, n = 71) valve replacement with a standard Hancock porcine bioprosthesis (HPB) from 1970 to 1983 were reviewed. A total of 665 patients discharged were followed for 5,099 patient‐years with an actuarial survival at 15 years of 52% ± 4.5%, for MVR, 37% ± 14% for AVR, and at 12 years of 52 ± 7.4% for MAVR. Embolic episodes occurred in 9 patients after AVR (0.7% ± 0.2% pt‐yr), in 61 after MVR (1.7% ± 0.2% pt‐yr), and in 6 after MAVR (1.7% ± 0.7% pt‐yr); actuarial freedom from emboli at 15 years is 91% ± 3.5% after AVR, 79% ± 14% after MVR, and at 12 years is 87% ± 5% after MAVR. Reoperation because of primary tissue failure (PTF) was performed in 47 patients with AVR (3.9% ± 0.5% pt‐yr), 91 with MVR (2.6% ± 0.3% pt‐yr), and in 13 with MAVR (4.1% ± 1.1% pt‐yr); actuarial freedom from PTF at 15 years is 41% ± 5.5% after MVR, 37% ± 10% after AVR, and at 12 years is 49% ± 13% after MAVR. After AVR and MVR, freedom from PTF is significantly better for patients over 50 years of age. HPB‐related complications occurred in 80 patients with AVR (6.3% ± 0.7% pt‐yr), 195 with MVR (5.5 ± 0.4 pt‐yr), and in 41 with MAVR (12.0% ± 1.8% pt‐yr); actuarial freedom all HPB‐related complications at 15 years is 25% ± 4% after MTR, 23% ± 7.5% after ATR, and at 12 years is 20 ± 8.5% after MAVR.

Failure of Hancock pericardial xenografts: Is prophylactic bioprosthetic replacement justified?

The incidence of major valve-related complications was evaluated in a series of patients in whom the Hancock pericardial xenograft was used for aortic (AVR; n = 84), mitral (MVR; n = 17) and mitral-aortic (MAVR; n = 13) valve replacement. At 7 years actuarial survival is 66% +/- 8% after AVR, 64% +/- 13% after MVR, and 41% +/- 15% after MAVR, whereas actuarial freedom from valve-related death is 79% +/- 7% after AVR, 78% +/- 13% after MVR, and 81% +/- 12% after MAVR. Actuarial freedom from thromboemboli and anticoagulant-related hemorrhage at 7 years is 93% +/- 4% and 98% +/- 2% after AVR and 83% +/- 10% and 88% +/- 11% after MVR; no such complications occurred after MAVR. Structural valve deterioration determined at reoperation, at autopsy, or by clinical investigation was observed in 34 patients with AVR (10.0 +/- 0.2%/patient-year), in 10 with MVR (10.6 +/- 3.3%/patient-year), and in 9 with MAVR (16.6 +/- 5.5%/patient-year). After AVR, 19 patients underwent reoperation and 2 died before reoperation; 4 patients with MVR underwent reoperation, and 7 patients with MAVR underwent reoperation and 1 died before reoperation. Seventy-eight percent of the current survivors (13 patients with AVR, 7 with MVR, and 1 with MAVR) have clinical evidence of valve failure. At 7 years actuarial freedom from structural deterioration of the Hancock pericardial xenograft is 25% +/- 7% after AVR, 29% +/- 14% after MVR, and 0% after MAVR.(ABSTRACT TRUNCATED AT 250 WORDS)

Long-term Durability of the Hancock Porcine Bioprosthesis Following Combined Mitral and Aortic Valve Replacement: An 11-Year Experience

Long-term evaluation of patients undergoing combined mitral and aortic valve replacement (MVR + AVR) with a porcine bioprosthesis provides the opportunity for a direct comparison of the durability of the mitral versus the aortic porcine bioprosthesis in the same patient. From 1970 to 1983, 71 patients underwent MVR + AVR with Hancock porcine bioprostheses. There were 46 men an 25 women ranging in age from 21 to 64 years (mean, 47.5 +/- 5 years). Sixteen patients (22.5%) died at operation. The survivors were followed from 0.2 to 11.5 years (mean, 5.7 +/- 3 years). Duration of follow-up was 313 patient-years and was 100% complete. Overall late mortality was 6.7 +/- 1.4% per patient-year (linearized incidence), and actuarial survival was 54.2 +/- 8% at 11 years. Endocarditis occurred in 4 patients (linearized incidence of 1.3 +/- 0.6% per patient-year); thromboembolic events were sustained by 4 patients (linearized incidence of 1.3 +/- 0.6% per patient-year); the event was fatal in 1 patient. Actuarial freedom from thromboembolism was 90 +/- 4.8% at 11 years. Reoperation for primary tissue failure was performed in 11 patients (linearized incidence of 3.5 +/- 1% per patient-year) with no deaths; in 7 patients both bioprostheses were explanted, and in 4, only the mitral bioprosthesis was replaced. The durability of explanted aortic and mitral porcine bioprostheses was not significantly different, and the evaluation of seven pairs of explanted aortic and mitral bioprostheses showed similar amounts of calcification. Actuarial freedom from reoperation because of primary tissue failure was 44.6 +/- 13.7% at 11 years.(ABSTRACT TRUNCATED AT 250 WORDS)

Extended follow-up of the standard Hancock porcine bioprosthesis.

We have reviewed 665 patients in whom the standard Hancock porcine bioprosthesis (HPB) was used for aortic (AVR = 173), mitral (MVR = 437), and mitral and aortic (MAVR = 55) valve replacement in the time interval from 1970 to 1983. After AVR, HPB‐related deaths occurred in 24 patients (1.7% ± 0.4% per patient‐year); 11 had thromboembolic episodes (0.8% ± 0.2% per patient‐year), 6 hemorrhages related to anticoagulants (0.4% ± 0.2% per patient‐year), 9 endocarditis (0.7% ± 0.2% per patient‐year), 7 prosthetic leak (0.5% ± 0.1 % per patient‐year), and 59 structural deterioration (4.3% ± 0.6% per patient‐year). At 16 years, actuarial survival is 40% ± 6%, freedom from thromboembolic episodes 89% ± 4%, from hemorrhages 90% ± 5%, from endocarditis 94% ± 2%, from prosthetic leak 95% ± 2%, and from structural deterioration 36% ± 6%. After MVR, HPB‐related deaths occurred in 64 patients (1.6% ± 0.2% per patient‐year); 68 had thromboembolic episodes (1.7% ± 0.2% per patient‐year), 28 hemorrhages (0.7% ± 0.1% per patient‐year), 12 endocarditis (0.3% ± 0.1% per patient‐year), 9 prosthetic leak (0.2% ± 0.1% per patient‐year), and 158 structural deterioration (4.0% ± 0.3% per patient‐year). At 18 years, actuarial survival is 33% ± 4%, freedom from thromboembolic episodes 57% ± 13%, from hemorrhages 81% ± 6%, from endocarditis 91% ± 4%, from prosthetic leak 98% ± 1%, and from structural deterioration 18% ± 5%. After MAVR there were 18 HPB‐related deaths (5.0% ± 1.3% per patient‐year); 6 patients had thromboembolic episodes (1.7% ± 0.2% per patient‐year), 6 hemorrhages (1.7% ± 0.2% per patient‐year), 11 endocarditis (3.1% ± 1.1% per patient‐year), 6 prosthetic leak (1.7% ± 0.7% per patient‐year), and 17 structural deterioration (4.8% ± 1.2% per patient‐year). At 14 years, actuarial survival is 26% ± 7%, freedom from thromboembolic episodes 85% ± 7%, from hemorrhages 80% ± 11%, from endocarditis 74% ± 7%, from prosthetic leak 93% ± 4%, and from structural deterioration 16% ± 10%. The HPB has shown excellent performance in the first decade that, however, becomes unacceptable thereafter due to the progressively increasing incidence of structural valve deterioration.

Influence of prosthetic design on durability of the liotta porcine valve in the mitral position

From March 1979 to December 1984, the Liotta low-profile porcine bioprosthesis was employed for mitral valve replacement in 71 patients to avoid potential left ventricle-prosthesis mismatch occasionally observed with the standard, high-profile, Hancock porcine xenograft. Follow-up of 61 operative survivors showed at 10 years an actuarial survival of 67% +/- 7%, freedom from thromboemboli of 96% +/- 2%, freedom from structural deterioration of 63% +/- 11% and freedom from all Liotta bioprosthesis-related complications of 53% +/- 10%. Complications related to excessive protrusion of the stent into the left ventricular cavity were eliminated with the Liotta bioprosthesis; the peculiar stent configuration, however, was responsible for an increased rate of structural deterioration requiring reoperation in 10 patients (2.8% +/- 0.9%/patient-year) at a mean interval of 76 +/- 18 months after mitral valve replacement (range, 45 to 106 months). Common findings in all explants were cusp prolapse, cusp tears, and commissural rupture related to various degrees of tissue calcification, constantly leading to severe prosthetic incompetence. As also shown experimentally, such structural changes have been attributed to increased systolic stresses on the closed cusps, favored by excessive reduction of the stent height. Our experience shows that the Liotta bioprosthesis used for mitral valve replacement does not provide any clear-cut advantage over standard porcine bioprostheses and that its long-term durability appears affected by the unique prosthetic design.

The risk of reoperation in patients with bioprosthetic valves.

The risk of operative mortality in patients undergoing a first reoperation for bioprosthetic failure was assessed in a series of patients reoperated upon during the last two decades (1970‐1990). A total of 330 such patients underwent replacement of 351 bioprostheses: 88 had aortic; 221 mitral; and 21 mitral and aortic bioprosthetic replacement. Indication for reoperation was in most cases structural valve deterioration (87%), followed by periprosthetic leak (7%) and endocarditis (6%). The operative mortality was significantly higher in patients who preoperatively were in New York Heart Association Functional Class IV or had a lower left ventricular function, In those reoperated because of prosthetic infection, and in those reoperated on an emergency basis. Structural valve deterioration was associated to a substantially low risk; operative mortality has improved in recent years, regardless of the indication for reoperation, partly due to the increasing experience and improved surgical techniques. Our results indicate that in recipients of bioprosthetic valves, careful follow‐up with closer surveillance of valve and cardiac function and earlier prosthetic replacement might contribute to reducing the risk of reoperation.

Mitral valve replacement with the Hancock, Björk-Shiley and Lillehei-Kaster prostheses. A comparison based on a 15-year follow-up.

The performance of the standard Hancock porcine bioprosthesis (HPB), the Björk-Shiley spherical disc prosthesis (BSP) and the Lillehei-Kaster tilting disc prosthesis (LKP) was compared over a 15-year follow-up in patients who underwent isolated mitral valve replacement (502 HPB, 183 LKP and 119 BSP). The cumulative duration of follow-up is 3,488 patient-years (mean, 8.0 +/- 3.7 years) for patients with a HPB, 1,302 patient-years (mean, 8.4 +/- 4.9 years) for patients with a LKP and 718 patient-years (mean, 7.1 +/- 5.6 years) for those with a BSP. At 15 years a significant difference was found among the 3 groups in freedom from (1) anticoagulant-related haemorrhages, between HPB (83% +/- 7%) and BSP (65% +/- 8%) recipients (P less than 0.05); (2) prosthetic dysfunction, BSP (96% +/- 3%) and LKP (83% +/- 6%) versus HPB (42% +/- 5%) recipients (P less than 0.001); (3) overall reoperations, BSP (94% +/- 3%) and LKP (89% +/- 3%) versus HPB (40% +/- 5%) recipients (P less than 0.001) and (4) prosthetic failure, BSP (88% +/- 4%) and LKP (71% +/- 6%) versus HPB (38% +/- 5%) recipients (P less than 0.001). No difference was found in actuarial survival, freedom from thromboembolic episodes, treatment failure and overall prosthesis-related complications. Our results confirm that the long-term performance of the HPB in the mitral position is adversely affected by the high incidence of tissue degeneration while haemorrhagic complications may limit the advantage of the longer durability of mechanical prostheses.(ABSTRACT TRUNCATED AT 250 WORDS)

The Hancock pericardial xenograft: incidence of early mechanical failures at a medium-term follow-up.

The Hancock pericardial xenograft has been used in our Institution since August 1981 as an alternative to porcine bioprostheses. Up to July 1984, 97 Hancock pericardial xenografts have been implanted in 84 patients; of 76 operative survivors with a mean age of 55.2 +/- 13 years (range 13-75 years), 50 had undergone aortic valve replacement, 16 mitral valve replacement and 10 mitral-aortic valve replacement. Follow-up ranged from 0.5 to 5.2 years with a cumulative duration of 239 patient/years and is 99% complete. Actuarial survival is 92% +/- 4% for patients with aortic valve replacement and 84% +/- 10% for patients with mitral valve replacement at 5 years, and 77% +/- 14% for those with mitral-aortic valve replacement at 4 years. Thromboembolic episodes occurred in 2 patients (1 after aortic and 1 after mitral valve replacement). The actuarial freedom from emboli is 100% for patients with mitral-aortic valve replacement at 4 years, and 96% +/- 3% for patients with aortic and 93% +/- 6% for patients with mitral valve replacement at 5 years. Reoperation was performed in 13 patients (9 aortic, 2 mitral and 2 mitral-aortic valve replacements), because of endocarditis in 3 (2 aortic and 1 mitral valve replacement), paravalvular leak in 1 (aortic valve replacement), and primary tissue failure in 9 (6 aortic, 1 mitral and 2 mitral-aortic valve replacements). Actuarial freedom from primary tissue failure is 72% +/- 9% for aortic and 83% +/- 8% for mitral Hancock pericardial xenografts at 5 years. Eleven xenografts explanted because of primary tissue failure were studied pathologically.(ABSTRACT TRUNCATED AT 250 WORDS)

Mode of late failure of the low-profile (Liotta) porcine bioprosthesis in the mitral position

Abstract The use of low-profile bioprostheses minimizes complications due to protrusion of the stent into the left ventricular cavity after mitral valve replacement. 1,2 Recent experimental work, however, indicates that excessive reduction of the stent height during bioprosthetic manufacture results in an increased stress on the cusps. 3 We report the pathologic findings in 6 low-profile Liotta porcine bioprostheses, which seem to confirm these results and suggest a peculiar mode of failure of such devices.