Bioprosthesis For Aortic Valve Replacement Research Articles

Impact of progressive sinotubular junction dilatation on valve competence of the 3F Aortic and Sorin Solo stentless bioprosthetic heart valves

The use of stentless bioprostheses for aortic valve replacement provides excellent haemodynamics; however, these valves bear the potential risk of progressive regurgitation over time. To overcome this disadvantage, a new generation of pericardial stentless prostheses has been developed. This study aims to assess the tolerance of such bioprotheses against progressive sinotubular junction dilatation. Five specimens of both the 3F Aortic and Sorin Solo stentless bioprotheses (diameter 25 mm) were investigated in a pulsatile flow simulator incorporating a device for gradual expansion of the sinotubular junction diameter. Closing characteristics were obtained by high-speed video imaging and the corresponding regurgitations were determined by ultrasonic flow measurements. The diameters D(R), at which primary distinct regurgitation occurs, were correlated to the original diameters D(A) and expressed as percentage values. The highest tolerance against sinotubular junction dilatation was found for the 3F Aortic (156+/-5%) compared to the Sorin Solo (145+/-6%, p=0.0127) bioprothesis. Visualisation of the valves revealed strong leaflet folding at labelled diameter, similar in both valve types. New-generation pericardial stentless bioprotheses provide favourable adaptability to sinotubular junction dilatation, more pronounced for the 3F prosthesis. Whether undue leaflet folding caused by the redundant tissue influences long-term function remains to be established.

Prospective randomized evaluation of stentless vs. stented aortic biologic prosthetic valves in the elderly at five years

Randomized trials comparing stentless to stented bioprostheses for aortic valve replacement in elderly are scarce. The aim of this study was early and mid-term evaluation of these bioprostheses, with regards to clinical outcome and hemodynamic performance. Between September 1999 and January 2001, 40 patients with aortic stenosis, over the age of 75 years, were randomly assigned to receive either the stented Perimount (n=20) or the stentless Prima Plus (n=20) bioprosthesis. Clinical outcomes, left ventricular mass regression, effective orifice area, ejection fraction and mean gradients were evaluated at discharge, six months, one year and five years after surgery. At five years, there were 5/20 (25%) deaths in the stentless group and 6/20 (30%) deaths in the stented group (all non-valve-related). There was one case of endocarditis in each group, early postoperatively. Overall, a significant decrease in left ventricular mass was found five years postoperatively. However, there was no significant difference in the rate and completeness of LV-mass regression between the groups (LV mass index 114+/-34.1 vs. 120+/-27.2). Furthermore, hemodynamic performance of the valves (mean gradient of 9.9+/-4.8 mmHg vs. 10.2+/-4.2 mmHg) did not differ significantly between the groups. At five years, stentless valves were not superior to the stented valves, with regards to hemodynamic performance, regression of left ventricular mass and clinical outcome.

Severe thrombocytopenia occurs in patients after aortic valve replacement with the Freedom Solo stentless bioprosthesis

Objectives: Stentless bioprostheses have been considered to achieve superior hemodynamics over stented bioprostheses for aortic valve replacement with improved long-term performance. We observed severe thrombocytopenia in patients who received the Sorin Freedom Solo aortic stentless pericardial bioprosthesis within the first days after implantation.

Thrombocytopenia after aortic valve replacement with the Freedom Solo stentless bioprosthesis

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

Short-term hemodynamic advantages of stentless CryoLife-O'Brien valve over stented bioprostheses for aortic valve replacement

For the CryoLife-O'Brien valve (CryoLife Inc, Kennesaw, GA, USA), implanted with a single suture line, we aimed to analyze the surgical requests and the hemodynamic results compared to stented bioprostheses. Two groups of patients requiring isolated aortic valve replacement from this population were compared retrospectively: 84 patients receiving the stentless CryoLife-O'Brien valve (Group A) and 94 patients receiving stented bioprostheses (Group B). Preoperative characteristics of patients were statistically equivalent for both groups. Statistically significant differences were observed only for operative durations and post-operative transprosthetic gradients: Aorta cross-clamp and cardio-pulmonary bypass durations were statistically longer for Group A than for Group B (45.9+/-5.7 min vs. 41.1+/-6.8 min; P<0.0001; and 64.3+/-11.6 min vs. 59.3+/-11.9 min, respectively; P=0.0053); maximal gradients and mean gradients were 19.9+/-10.9 mmHg vs. 25.6+/-10.4 mmHg (P=0.0008) and 10.8+/-5.3 mmHg vs. 14.8+/-6.4 mmHg (P<0.0001). Few surgical constraints and early post-operative hemodynamic efficiency of the stentless CryoLife-O'Brien valve means that this bioprosthesis can be intented in current practice for the aortic valve replacement in elderly patients.

Durability of pericardial versus porcine aortic valves

ObjectivesThis study compares the long-term performance of the Carpentier-Edwards (CE) porcine bioprosthesis and the CE pericardial bioprosthesis for aortic valve replacement (AVR). BackgroundWith new bioprostheses on the horizon, there is renewed interest in how the long-term durability of current pericardial bioprostheses compares with the traditional porcine bioprosthesis. MethodsWe reviewed 518 AVR with CE porcine valves from 1974 to 1996 and 1,021 AVR with CE pericardial valves from 1991 to 2002. The age distribution and clinical profiles were similar for both groups. The total (mean) follow-up was 3,322 (6.4) years for porcine and 2,556 (2.5) years for pericardial. ResultsLong-term mortality was similar (p = 0.29) for porcine and pericardial, with 10-year survival rates of 34 ± 2% and 38 ± 6%, respectively. Ten-year freedom from major adverse cardiac events was also similar for both (respectively): thromboembolism (80 ± 2% and 87 ± 2%; p = 0.24); endocarditis (98 ± 1% and 99 ± 1%; p = 0.30). However, 10-year freedom from explant was lower for porcine (90 ± 2%) than for pericardial (97 ± 1%, p = 0.04). Reasons for explant for porcine were structural valve deterioration (SVD) (n = 25), endocarditis (n = 4), and periprosthetic leak (n = 2). The reasons for explant for pericardial were SVD (n = 4), endocarditis (n = 4) and periprosthetic leak (n = 1). ConclusionsThe current CE pericardial valve offers better midterm durability than the traditional CE porcine valve. Its freedom from SVD and reoperation makes it our current bioprosthesis of choice for AVR in appropriately selected patients.

Choice of a mechanical valve or a bioprosthesis for AVR: does CABG matter?

Mechanical valves and bioprostheses are the commonly used devices in aortic valve replacement (AVR). Many patients with valvular disease also require concomitant coronary artery bypass grafting (CABG). We used a microsimulation model to provide insight into the outcomes of patients after AVR with mechanical valves and stented bioprostheses, with and without CABG, and to determine the age-thresholds or age crossover points in outcomes between the two valve types. We conducted a meta-analysis of published results after primary AVR with mechanical prostheses (nine reports, 4274 patients, 25,726 patient-years) and stented porcine bioprostheses (13 reports, 9007 patients, 54,151 patient-years) to estimate risks of valve-related events. A hazard ratio of 1.3 was used to incorporate the effect of CABG on long-term survival. Estimates were entered into a microsimulation model, which was then used to predict the outcomes of patients after AVR, with and without CABG. The model calculations were validated using a large data set from Portland, USA. For a 65-year-old male without CABG, the life expectancy (LE) was 11.2 and 11.6 years and the event-free life expectancy (EFLE) was 8.2 and 8.9 years, respectively, after implantation with mechanical valves and bioprostheses. The lifetime risk of at least one valve-related event was 51 and 47%, respectively. The age crossover point between the two valve types, considering the above outcome parameters, was 59, 60 and 63 years, respectively. CABG reduced LE and consequently EFLE and lifetime risk of an event, but only minimally influenced the patient age crossover points. The model calculations showed good agreement with the Portland data. The currently recommended patient age for using a bioprosthesis (65 years) could be lowered further, irrespective of concomitant CABG. The trade-off between the reduced risks of bioprosthetic failure and of hemorrhage in mechanical valves, resulting from a lower LE, minimized the effect of CABG on the age crossover points between the two valve types.

Stentless bioprostheses in aortic root disease.

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

Hancock versus stentless bioprostheses for aortic valve replacement in patients older than 75 years

Background. Stented aortic bioprostheses are routinely used in elderly patients. The stent, however, is obstructive and implies several hazards. Stentless aortic valves appear to be hemodynamically advantageous. However, their implantation is longer and technically more demanding, and durability is still under investigation. Methods. Between January 1993 and December 1996, 77 patients (28 men) were prospectively randomized to undergo aortic valve replacement using the Hancock valves (group A: 40 patients, 16 men; age, 77 ± 3 years; body surface area, 1.7 ± 0.17 m 2) or a stentless bioprostheses (group B: 37 patients, 12 men; age, 76 ± 2 years; body surface area, 1.7 ± 0.15 m 2; Biocor, 17; Toronto SPV, 20). Preoperative variables were not significantly different between the two groups. Bypass time was 123 ± 46 versus 133 ± 51 minutes, and aortic cross-clamp time was 83 ± 26 versus 95 ± 24 minutes for group A and group B, respectively (not significant). Seven patients in group A (17.5%) and 5 in group B (13.5%) had enlargement of the aortic annulus. Valve size normalized to body surface area was 13.7 ± 1.5 versus 14.1 ± 1.6 mm/m 2 for group A and group B, respectively (not significant). Eleven patients in group A (27.5%) and 5 in group B (13.5%) had concomitant myocardial revascularization. Results. Overall perioperative mortality was 5% in group A (low cardiac output in 2 patients), and 8% in group B (low cardiac output in 1; major neurologic event in 2). Follow-up is 97% complete (group A, 14.5 ± 10 months; group B, 18.5 ± 12 months). One patient in group B died at 28 months of myocardial infarction. Actuarial survival at 12 and 24 months is 92% versus 91% and 92% versus 81% for group A and group B, respectively. At 6 months, patients in group A showed a peak transaortic gradient of 25 ± 7 versus 20 ± 9 mm Hg in group B. Progressive regression of left ventricular mass expressed as a percentage of preoperative value was 10.5% and 19% for group A and group B at 1 year postoperatively (not significant). Conclusions. Stentless valves represent a valuable alternative to conventional prostheses in patients older than 75 years, although no great advantages with their use emerge from this study. Continued evaluation particularly with regard to evidence of left ventricular remodeling and valve degeneration in the long term is warranted. aortic valve, elderly, xenograft, stented bioprostheses

Carpentier-Edwards Bioprosthesis: Structural Deterioration by Age Groups

The Carpentier-Edwards supra-annular porcine bioprosthesis (second generation prosthesis) was implanted in 2438 patients in 2482 operations between 1982 and 1992. The mean age of the population was 64 years with a range from 21 years to 89 years. There were 1334 aortic and 934 mitral valve replacements. The population was divided into five groups: 21 to 40 years (n = 132); 41 to 50 years (n = 189); 51 to 60 years (n = 454); 61 to 70 years (n = 849); and over 70 years (n = 858). There was no difference in sunival by valve position for age groups 21 to 40 years and 41 to 50 years. Sunival within the age groups 51 to 60 years, 61 to 70 years, and over 70 years was greater for patients with aortic compared with mitral and multiple valve replacements. The freedom from structural valve deterioration at 10 years for all age groups was highest for valves in the aortic position. Patients with valves in the mitral position had a higher freedom from structural valve deterioration at 10 years than those who had multiple valve replacement, although not all the differences were significant. There was a lower incidence of structural valve deterioration in the older age groups. We concluded that the use of the Carpentier-Edwards supra-annular porcine bioprosthesis for aortic valve replacement can be extended to patients over 60 years of age, while its use for mitral valve replacement can be extended to those above 70 years of age.

The stentless Toronto SPV bioprosthesis for aortic valve replacement

The Toronto SPV bioprosthesis for aortic valve replacement has been prospectively evaluated in 100 patients, since March 1993. Intraoperative transoesophageal and postoperative transthoracic echocardiography were used to assess valve function. Follow-up was complete in 74 patients at 6 months and in 38 patients at 1 year. The average valve size implanted was 26.5 mm. Some 37 patients had additional coronary artery bypass grafting surgery. The hospital mortality rate was 4%. Non-structural valve dysfunction occurred in one patient and late endocarditis in another patient required operation. There were no other valve complications. None of the patients developed clinically relevant aortic valve incompetence during follow-up and there was a significant decrease in pressure gradients, increase in valve orifice areas and decrease in left ventricular hypertrophy. Copyright © 1996 The International Society for Cardiovascular Surgery.

Hemodynamic and clinical evaluation of the Hancock xenograft bioprosthesis for aortic valve replacement (with emphasis on management of the small aortic root)

One hundred twenty-nine consecutive patients underwent isolated aortic valve replacement with the Hancock porcine xenograft between July, 1974, and December, 1976. The hospital mortality rate was 3.9 percent. No patient was treated with anticoagulants, and valve-related complications were extremely rare. The smaller prosthetic sizes (19 and 21 mm. stent diameter) should be used with extreme caution, and the 19 mm. prosthesis should probably never be used in the audult patient. Two methods of managing the small aortic root are emphasized: one to avoid using the smaller prosthetic size in adults and the other to alter greatly the root size in children who have a hypoplastic aortic annulus. Acceptable calculated orifice sizes and left ventricular--aortic (LV-Ao) pressure gradients may be obtained with the 23 mm. or larger prostheses. Actuarial survival curves show 92 percent of patients alive and well at 24 months' follow-up.