Toronto Stentless Porcine Valve Research Articles

Long-term clinical outcomes of the Toronto stentless porcine valve: 15-year results from dual centers.

The purpose of this study is to examine the long-term durability of the Toronto stentless porcine valve (SPV) in the aortic position (St Jude Medical, Minneapolis, MN). We assessed the long-term clinical outcomes of 515 patients with aortic valve replacement (AVR) with the Toronto SPV from 1987 to 2001 at two centers, excluding early (<30 days) death. Median follow-up was 11.5 years (maximum 19.0 years). Average age was 64.2 ± 10.8 years, and females were 34% (173/515). The incidence of prosthesis-patient mismatch was low, 10.9%. Overall survival was 90.7 ± 1.3%, 75.4 ± 2.0%, and 56.8 ± 3.2% at 5, 10, and 15 years, respectivelyafter surgery. Over the follow-up duration, 116 patients (23%) underwent repeated AVR: 90 for structural valve deterioration (SVD), 12 for endocarditis, 10 nonstructural valve dysfunction (10 aortic regurgitation due to aorta dilatation), and four for other reasons. The cumulative incidence of repeated AVR with death as a competing risk was 1.4% (95% confidence interval [CI], 0.6-2.7), 11.1% (95% CI, 8.4-14.2), and 34.4% (95% CI, 28.8-40.2) at 5, 10, and 15 years, respectively. Reoperative mortality was 5.2% (6/116). In SVD, the regurgitation type was dominant (82%). The Toronto SPV is associated with excellent survival and durability during the first decade of follow-up. However, regurgitation type of SVD increases from 10 years after operation with acceptable reoperative mortality. These findings may assist with prosthesis selection and reintervention strategy for failing stentless bioprosthesis.

Medium to long-term clinical outcome following stentless aortic valve replacement: comparison between allograft and xenograft valves

The xenograft stentless valve was designed to emulate the haemodynamic performance of the allograft. Early outcomes using either surgical option (stentless xenograft valve or allograft) have been similar. However, follow-up outcomes remain to be compared. Between 1st January 1991 and 1st January 2001, 415 patients underwent aortic valve replacement. Two hundred and seventeen patients received an allograft and in 198 patients a Toronto stentless porcine valve (TSPV) was implanted. Mean time to follow-up was 6.3+/-4.4 years. Ten years freedom from structural valve deterioration (SVD) (TSPV 86+/-5%, allograft 82+/-5%, P=0.49) and freedom from reoperation (RE) (TSPV 80+/-4% vs. allograft 85+/-4%, P=0.61) were not significantly different. The TSPV was associated with significantly worse actuarial survival than the homograft (TSPV 40+/-4% vs. homograft 55+/-4%, P=0.02). However, after adjustment for other variables using a multivariate model, TSPV use was not an independent predictor of impaired late survival (LS) (P=0.44). Kaplan-Meier analysis in a subgroup of patients aged 45-65 years comparing LS, RE and SVD between xenografts and allografts identified similar results. The porcine stentless valve may be associated with similar clinical performance to the allograft over the medium to long-term.

Are stentless valves hemodynamically superior to stented valves? Long-term follow-up of a randomized trial comparing Carpentier–Edwards pericardial valve with the Toronto Stentless Porcine Valve

The benefit of stentless valves remains in question. In 1999, a randomized trial comparing stentless and stented valves was unable to demonstrate any hemodynamic or clinical benefits at 1 year after implantation. This study reviews long-term outcomes of patients randomized in the aforementioned trial. Between 1996 and 1999, 99 patients undergoing aortic valve replacement were randomized to receive either a stented Carpentier-Edwards pericardial valve (CE) (Edwards Lifesciences, Irvine, Calif) or a Toronto Stentless Porcine Valve (SPV) (St Jude Medical, Minneapolis, Minn). Among these, 38 patients were available for late echocardiographic follow-up (CE, n = 17; SPV, n = 21). Echocardiographic analysis was undertaken both at rest and with dobutamine stress, and functional status (Duke Activity Status Index) was compared at a mean of 9.3 years postoperatively (range, 7.5-11.1 years). Clinical follow-up was 82% complete at a mean of 10.3 years postoperatively (range, 7.5-12.2 years). Preoperative characteristics were similar between groups. Effective orifice areas increased in both groups over time. Although there were no differences in effective orifice areas at 1 year, at 9 years, effective orifice areas were significantly greater in the SPV group (CE, 1.49 +/- 0.59 cm(2); SPV, 2.00 +/- 0.53 cm(2); P = .011). Similarly, mean and peak gradients decreased in both groups over time; however, at 9 years, gradients were lower in the SPV group (mean: CE, 10.8 +/- 3.8 mm Hg; SPV, 7.8 +/- 4.8 mm Hg; P = .011; peak: CE, 20.4 +/- 6.5 mm Hg; SPV, 14.6 +/- 7.1 mm Hg; P = .022). Such differences were magnified with dobutamine stress (mean: CE, 22.7 +/- 6.1 mm Hg; SPV, 15.3 +/- 8.4 mm Hg; P = .008; peak: CE, 48.1 +/- 11.8 mm Hg; SPV, 30.8 +/- 17.7 mm Hg; P = .001). Ventricular mass regression occurred in both groups; however, no differences were demonstrated between groups either on echocardiographic, magnetic resonance imaging, or biochemical (plasma B-type [brain] natriuretic peptide) assessment (P = .74). Similarly, Duke Activity Status Index scores of functional status improved in both groups over time; however, no differences were noted between groups (CE, 27.5 +/- 19.1; SPV, 19.9 +/- 12.0; P = .69). Freedom from reoperation at 12 years was 92% +/- 5% in patients with CEs and 75% +/- 5% in patients with SPVs (P = .65). Freedom from valve-related morbidity at 12 years was 82% +/- 7% in patients with CEs and 55% +/- 7% in patients with SPVs (P = .05). Finally, 12-year actuarial survival was 35% +/- 7% in patients with CEs and 52% +/- 7% in patients with SPVs (P = .37). Although offering improved hemodynamic outcomes, the SPV did not afford superior mass regression or improved clinical outcomes up to 12 years after implantation.

Novel Approach to Right Ventricular Outflow Tract Reconstruction Using a Stentless Porcine Valve

The use of a stentless aortic bioprosthesis offers the advantages of a larger effective valve orifice size, reduced transvalvular gradients, and improved hemodynamics versus stented valves. We hypothesized that these features would make the Toronto stentless porcine valve a preferred choice for patients with congenital abnormalities of the right ventricular outflow tract. We retrospectively reviewed medical records of 21 patients with tetralogy of Fallot who subsequently underwent right ventricular outflow tract reconstruction during a 6-year period. The majority of patients received a 29-mm valve (n = 13), 5 received a 27-mm valve, with 1 each additional implant of a 19-, 22-, and 23-mm prosthesis. The mean age and weight were 24.5 years (range, 7 to 54 years) and 55.6 kg (range, 13.9 to 98.0 kg), respectively. Preoperatively, all patients had severe pulmonary insufficiency, mixed with mild to moderate stenosis in 2. The duration of postoperative echocardiographic follow-up ranged from 10 to 70 months (mean, 37.7 months). At the time of most recent follow-up, pulmonary insufficiency was graded as zero to trace in 47.4% (9 of 19 patients), mild in 42.1% (8 of 19 patients), and moderate in 10.5%, with 6 patients (31.6%) having concomitant pulmonary stenosis. The most recent mean and peak transvalvular gradients averaged 17.4 mm Hg (range, 11 to 24 mm Hg) and 26 mm Hg (range, 13 to 42 mm Hg), respectively. There have been no valve-related complications or explants, with one late death as a result of a noncardiac cause. The stentless porcine valve is well suited for valve replacement in children, adolescents, and adults with congenital abnormalities of the right ventricular outflow tract, regardless of patient or valve size, particularly when significant downstream hemodynamic abnormalities exist.

Stentless Aortic Valve Reoperations: A Surgical Challenge

Stentless aortic valve reoperations may become more common as these bioprostheses reach the limits of their durability. Relatively few studies have examined stentless valve reoperation, and we therefore reviewed our results for these procedures. All patients with stentless valves undergoing redo aortic valve replacement (AVR) at our institution were examined (n = 57). Ten patients had a prior Freestyle valve (Medtronic, Minneapolis, MN), and 47 patients had a Toronto stentless porcine valve (SPV; St. Jude Medical St Paul, MN). Redo AVR was performed 8.4 +/- 3.7 years (range, 0.1 to 16.5 years) after stentless valve implantation. Reoperations were elective in 27 patients (49%), and 30 (51%) underwent urgent or emergency procedures. The indication for redo AVR was structural valve dysfunction in 48 patients (84%), acute endocarditis in 7 (12%), and other in 2 (4%). Aortic insufficiency was present in 47 patients (82%). A total of 36 aortic root replacement operations (63% of patients) were required, of which 19 were secondary to severe adhesions between the stentless valve and the native aortic root. Operative mortality was 11% (n = 6) for the entire group. Mortality was higher in patients undergoing redo AVR less than 1 year after stentless valve implantation versus more than 1 year (67% versus 7%, p = 0.03). Long-term survival at 5 years postoperatively was 79% +/- 7% in all patients, and 81% of survivors were in New York Heart Association class I or II. Reoperation after stentless AVR is a challenging procedure that frequently requires aortic root replacement. Stentless valve reoperation is associated with an increased risk of death, particularly in patients operated on within 1 year of implantation.

Pathology of infectious and inflammatory diseases in prosthetic heart valves

Prosthetic heart valves, both mechanical and biological (xenograft valves, stented or unstented), show an inflammatory reaction (infective endocarditis), associated predominantly with bacterial/fungal infection. Somewhat surprisingly, no immune-mediated reaction has been reported thus far. This may, among other reasons, be related to the fact that the tissues are "fixed" with aldehydes and are virtually isolated from host circulation, separated by synthetic material (the valve stent and the fabric covering it). Stentless valves (especially these without fabric covering them), however, have no such "isolation" from the host circulation. While the Toronto-Stentless Porcine Valve has a covering of fabric, the Medtronic Freestyle valve has no such covering. It is perhaps not so surprising therefore that at the intermediate time point of 5 to 6 years, some valves are beginning to show such an immune reaction.

The subcoronary Toronto stentless versus supra-annular Perimount stented replacement aortic valve: Early clinical and hemodynamic results of a randomized comparison in 160 patients

A stentless valve is expected to be hemodynamically superior to a stented valve. The aim of this study was to compare early postoperative hemodynamic function and clinical events in a randomized, prospective series of 160 stentless and stented biological replacement aortic valves. We randomized 160 consecutive patients on 1 surgeon's list to receive either a Toronto stentless porcine valve (St Jude Medical, Inc, St Paul, Minn) or a Perimount stented bovine pericardial valve (Edwards Lifesciences, Irvine, Calif). Echocardiography was performed at discharge, between 3 and 6 months, and at 1 year after surgery. Statistical analysis was performed by both intention to treat and actual valves implanted. The mean labeled size of both designs of valve was 24.7. There were no statistically significant differences in results at any time interval or whether analysis was performed by actual valves implanted or intention to treat. At 3 to 6 months for the Toronto versus the Perimount valve, the effective orifice area was 1.58 versus 1.66 cm2, the mean pressure difference was 7.54 versus 7.42 mm Hg, and the peak velocity was 2.07 versus 2.0.1 m/s. There was no difference in mortality, regression of left ventricular hypertrophy, or complications other than paraprosthetic regurgitation at 12 months or on follow-up for a proportion of the sample to 8 years. The incidence of regurgitation through the valves was similar for Toronto (10%) and Perimount (13.8%) at 1 year, but mild paraprosthetic regurgitation was found in 5 patients with the Perimount valve and none with Toronto valves. There were no significant differences in hemodynamic function or clinical events between the stented and stentless biological valves chosen for comparison in the early postoperative period or in preliminary follow-up to 5 years.

Morphological findings in explanted Toronto stentless porcine valves

Background: Stentless porcine valves have many documented advantages over stented valves. Since its introduction in 1991, the Toronto stentless porcine valve (T-SPV) has shown excellent hemodynamic performance. Methods: A total of 332 T-SPVs have been implanted at our institution up to December 2003, 25 of which have been explanted at surgery. Herein, we report a study of 30 explanted T-SPVs seen at our institution over a 5-year period. Results: The mean patient age at explant was 61.2±11.8 years with a mean implant duration of 100.7±27.8 months (after excluding one valve removed early postoperatively for infective endocarditis). Twenty-seven of 30 valves (90%) showed structural deterioration characterized by tissue degeneration, cusp tears, calcification, and lipid insudation. Eight valves (26.7%) showed evidence of calcification on gross inspection and a total of 23 valves (76.7%) showed at least one microscopic focus of calcification, located primarily in the basal and commissural regions of the cusp. Twenty valves (66.6%) showed cusp tears. Pannus was visible grossly on the surface of 27 of 30 valves (90%), while histologically, at least some degree of pannus was observed on both the inflow and outflow surfaces of all but two valves. Twelve T-SPV (40.0%) showed calcification in the porcine aortic tissue, four of which involved calcification of the porcine muscle shelf in the right coronary cusp. Two T-SPV showed no significant structural deterioration. Their clinical reason for explantation was incompetence or infective endocarditis. Conclusion: With a freedom from reoperation of about 87.0% at up to 10 years, the T-SPV shows excellent durability. The majority of explanted valves show structural valve deterioration similar to that seen in other porcine heart valves.

Stentless vs. Stented Aortic Valve Replacement: Left Ventricular Mass Regression

The aim of this retrospective study was to evaluate the time-related regression of left ventricular hypertrophy after stentless vs. stented aortic valve replacement. From January 1992 to December 2002, 145 patients had a Toronto stentless porcine valve and 106 had a stented Carpentier-Edwards aortic valve replacement. Over a 10-year follow-up, survival was superior in the Toronto group vs. the Carpentier-Edwards group (84% vs. 74% at 4 years; 78% vs. 68% at 6 years; p < 0.001). A significant and constant reduction of peak and mean transvalvular gradients after valve replacement resulted in substantial regression of left ventricular mass index in both groups, which did not reach statistical significance. However, this phenomenon stopped at 3 years, and left ventricular mass index increased slowly after 5 years. Stentless and stented bioprostheses both showed good early and late clinical and hemodynamic outcomes, with the advantage of better midterm survival for stentless xenografts.

Long-Term Results of Aortic Valve Replacement With the St. Jude Toronto Stentless Porcine Valve

Background Long-term survival and freedom from valve-related events of the St. Jude Toronto stentless porcine valve (SPV) are unknown. The aim of this study was to investigate late clinical outcomes after aortic valve replacement with the Toronto SPV. Methods Between 1992 and 2000, 200 patients (131 males, 69 females) underwent aortic valve replacement with the Toronto SPV. Mean patient age at implantation was 64.6 ± 10.9 years (range 33 to 82 years). At the time of operation, 32%, 51%, and 17% of patients were in New York Heart Association class I/II, III, and IV, respectively. Aortic stenosis, aortic insufficiency, and combined lesions were present in 64%, 13.5%, and 22.5% of patients preoperatively. Concomitant coronary artery bypass grafting was performed in 34.5% of patients. Results Perioperative mortality occurred in 2.5% (5/200) of patients. There were 31 late deaths. Actuarial survival at 5 and 10 years was 89.2% and 68.0%, respectively. There was no significant difference in overall actuarial survival between isolated valve patients and valve plus coronary artery bypass grafting patients, 71% versus 62% respectively, p = 0.85. Actuarial freedom from valve reoperation at 5 and 10 years was 97.6% and 79.9%, respectively. Actuarial freedom from structural valve deterioration was 98.8% at 5 years and declined to 77.9% at 10 years. Freedom from structural valve deterioration was poorer in patients with preoperative aortic insufficiency or bicuspid disease. Actuarial freedom from embolic events and endocarditis at 10 years were 94.6% and 95.9%, respectively. Conclusions Although early clinical results were excellent, a significant increase in hazard for structural valve deterioration occurred in late follow-up.

Candida parapsilosis: Two Cases of Endocarditis in Association with the Toronto Stentless Porcine Valve

Candida parapsilosis endocarditis in association with prosthetic heart valves is rare. We report the first two cases of C. parapsilosis endocarditis on the Toronto stentless porcine valve (TSPV) and the first reported case of successful elimination of infection without lifelong antifungal therapy.

Are stentless valves hemodynamically superior to stented valves? A prospective randomized trial

Background. Although stentless aortic bioprostheses are believed to offer improved outcomes, hemodynamic benefits remain unsubstantiated. Methods. Fifty-three patients were randomized to receive the stented C-E pericardial valve (CE) and 46 patients the Toronto Stentless Porcine valve (SPV). Annuli were sized for the optimal insertion of both valve types, such that surgeons were required to commit to specific valve sizes before randomization. Echocardiographic measurements and functional status (Duke Activity Status Index) were assessed at 3 and 12 months postoperatively. Results. Although cardiopulmonary bypass times (CE: 118.6 ± 36.3 minutes; SPV: 148.5 ± 30.9 minutes; p = 0.0001) and aortic cross-clamp times (CE: 95.4 ± 28.6 minutes; SPV: 123.6 ± 24.1 minutes; p = 0.0001) were significantly prolonged in the SPV group, perioperative morbidity and mortality was similar between groups. Neither valve offered a superior internal diameter for any given annular diameter (mean decrease in left ventricular outflow tract diameter after valvular implantation: SPV: 3.4 ± 1.11 mm versus CE: 3.7 ± 1.33 mm;E p = 0.25). Although labeled mean valve size was significantly larger in the SPV group, the actual mean valve size based on internal valvular diameter was no different between groups (CE: 21.9 ± 2.0 mm; SPV: 22.3 ± 2.0 mm; p = 0.286). Although effective orifice areas increased, and mean and peak transvalvular gradients decreased in both groups over time, no differences were demonstrated between groups at 12 months. Similarly, although significant regression of left ventricular mass was accomplished in both groups over time, no differences were demonstrated between groups. Finally, Duke Activity Status Index scores of functional status improved in both groups over time; however, no differences were noted between groups at 12 months postoperatively. Conclusions. Although offering excellent outcomes, stentless valves did not demonstrate superior hemodynamic indices in comparison to stented valves up to 12 months after implantation.

Exercise hemodynamics of aortic prostheses: comparison between stentless bioprostheses and mechanical valves

Background. Nonstented bioprostheses have been associated with lower resting gradients than stented bioprostheses or mechanical valves. We compared the hemodynamic performance of nonstented bioprostheses and mechanical valves with normal native aortic valves at rest and exercise. Methods. Dobutamine echocardiography was used to assess gradients and effective orifice area index at rest and exercise in patients with the Toronto stentless porcine valve (TSPV; n = 13; mean implant size 25.7 mm), Medtronic Freestyle (FR; n = 11; mean implant size 23.9 mm), Sorin Bicarbon (SOR; n = 11; mean implant size 24.5 mm), St. Jude Medical (SJM; n = 10; mean implant size 21.3 mm), and normal native aortic valves (NOR; n = 10). Results. All groups demonstrated a major rise in cardiac output at maximal dobutamine infusion. At rest and exercise, respectively, mean gradients were 5.48 ± 1.1 mm Hg and 5.83 ± 0.9 mm Hg for TSPV, 5.68 ± 1.2 mm Hg and 7.50 ± 1.7 mm Hg for FR, 10.29 ± 1.4 mm Hg and 20.78 ± 2.7 mm Hg for SJM, 5.26 ± 0.8 mm Hg and 11.1 ± 1.8 mm Hg for SOR, and 1.54 ± 0.4 mm Hg and 2.18 ± 0.7 mm Hg for NOR. In comparison with normal valves, both stentless groups showed no change in mean gradient at exercise, whereas both mechanical groups showed an increase in gradient at exercise ( p < 0.04). Conclusions. Stentless valves behave similarly to normal aortic valves in that there is almost no increase in gradient at exercise. Both mechanical valve groups showed increased gradients at exercise, suggesting that these valves obstruct blood flow. Our data add further evidence that stentless valves are hemodynamically superior to mechanical valves in the aortic position.

Clinical outcomes after aortic valve replacement with the Toronto stentless porcine valve

Background. Hemodynamic benefits of the Toronto stentless porcine valve have been documented. Clinical well-being and freedom from major valve-related events have been less well defined.Methods. A total of 447 patients were prospectively followed for up to 8 years (1,745.2 valve years total, 3.9 valve years/patient). The patient demographics included 66% men, mean age 65 years, New York Heart Association functional class III–IV 55%, concomitant coronary artery bypass grafting 41%.Results. We found that 83.7% of patients were in New York Heart Association functional class I and 80.8% had 0 to 1+ aortic insufficiency. Mean gradient at 6 years (n = 75) was 4.4 mm Hg and mean effective orifice area (EOA) 2.4 cm2. Late adverse event rates per patient per year were: embolism 1.0%, endocarditis 0.4%, thrombosis 0%, structural deterioration 0.2%, explant 0.3%, and valve-related death 0.6%. Freedom from valve-related death at 6 years was 95.8%; from cardiac death 96.3%. Freedom from endocarditis was 98.4%, from embolism 93.9%, from structural deterioration 97.4%, and freedom from explant 98.1%. For patients older than 60 years, freedom from structural deterioration was 100%.Conclusions. These results confirm satisfactory clinical outcomes after aortic valve replacement with the Toronto stentless porcine valve, with a low incidence of valve-related adverse events as long as 96 months after valve replacement.

Current status of stentless aortic xenografts.

The introduction of the Toronto stentless porcine valve (SPV) (St. Jude, Minneapolis, MN), recently approved by the Food and Drug Administration following a 6-year multi-institutional clinical trial from 1991 to 1997, reflects an evolutionary pursuit of an ideal valve substitute, namely, low thrombogenicity, freedom from anticoagulation, durability, easy availability, resistance to infection, and easy implantability. Currently, four different types of valve replacement have been time tested: mechanical valves, cryopreserved aortic homograft, stented heterograft, and pulmonary autograft (Ross procedure), and none of the available valve substitutes meet all the criteria of an ideal valve. The mechanical valve's favorable properties of durability and easy implantability are susceptible to thrombus formation, which requires lifelong anticoagulation. Although the aortic homografts are durable, with low incidence of infection and thrombogenicity, their widespread application has been limited by the lack of availability. The pulmonary autograft, with its native aortic valve properties, has been shunned by some surgeons because it requires a demanding technical expertise in implantation and needs an allograft in the pulmonary position. Stented xenografts are characterized by "off-the-shelf" availability, freedom from anticoagulation, easy implantability, and low incidence of infection. Its major drawback has been its limited durability. Another limitation is its residual transvalvular gradient. A modified version, a stentless xenograft, has been introduced to improve hemodynamic profiles in the hope of subsequent superior structural durability and patient survival. Two valves have been approved by the Food and Drug Administration, the Toronto SPV and the Freestyle valve (Medtronic, Minneapolis, MN). At The Methodist Hospital and the Baylor College of Medicine, the Toronto SPV stentless valve has been our stentless xenograft valve of choice. We therefore review the historical evolution, design advantages, surgical techniques, and clinical outcomes of this valve.

The Toronto SPV bioprosthesis: clinical and hemodynamic results at 6 years

Background. The Toronto SPV (stentless porcine valve) bioprosthesis has been in use for aortic valve replacement since July 1991. Before its approval by the Food and Drug Administration, 635 patients were enrolled in a prospective observational clinical trial in eight centers. This report is an update on that trial. Methods. There were 419 men and 216 women whose mean age was 66 years, range 33 to 93 years. In addition to aortic valve replacement, 264 patients also had coronary artery bypass, 9 had mitral valve repair, and 7 had replacement of the ascending aorta. The external diameter of most valves implanted was 25 mm or greater. Echocardiography has been done annually. The follow-up for this report was closed in September 1998 and mean follow-up was 2.7 years, range 0 to 6.3 years. Results. There were 17 operative and 38 late deaths. Actuarial survival was 82.6% at 6 years. Freedom from morbid events at 6 years was 90% for cardiac-related deaths, 93.6% for all thromboembolic events, 98.6% for endocarditis, 98.2% for repeat aortic valve replacement, and 100% for primary tissue failure. Approximately 85% of patients have no aortic insufficiency, with no change in this proportion during the first 6 years of observation. The mean systolic gradient decreased during the first 6 months and remained unchanged over the years. It was approximately 5 mm Hg for all patients. Most patients (81%) are free from cardiac symptoms. Conclusions. This porcine bioprosthetic valve has provided excellent clinical and hemodynamic results after aortic valve replacement. Longer follow-up is needed to determine its durability and the potential benefits of its hemodynamic features.

The Toronto stentless porcine valve in 100 consecutive elderly patients

The Toronto stentless porcine valve in 100 consecutive elderly patients

Four-year experience with the Toronto stentless porcine valve

Four-year experience with the Toronto stentless porcine valve

Left ventricular mass reduction after aortic valve replacement: homografts, stentless and stented valves

Background. We studied the effect of four different types of prosthetic aortic valves on time course and extent of regression of left ventricular hypertrophy after aortic valve replacement for aortic stenosis.Methods. Four groups of 10 patients each were randomly assigned to receive: (1) aortic homograft preserved in antibiotic solution at 4°C, (2) Toronto stentless porcine valve, (3) Medtronic Freestyle stentless valve, or (4) Medtronic Intact aortic valve. The left ventricular mass index, effective orifice area index, and peak and mean transaortic gradients were measured by Doppler echocardiography before the operation and 8 months postoperatively.Results. The hemodynamic performance indices were much better for the homograft and stentless valves than for the stented one. The absolute left ventricular mass index reduction was greater in the homograft group compared with the Intact (p = 0.0004) and Toronto (p = 0.007) groups. The extent of percent left ventricular mass index reduction was greater only in the homograft group versus Intact group (p = 0.005). The multilinear regression analysis showed that the only predictors of a larger percentage of left ventricular mass index reduction were the homograft type, a higher valve size index, and a higher preoperative left ventricular mass index.Conclusions. When a stentless or homograft aortic valve was used instead of a stented valve to replace a stenotic aortic valve there was more complete or at least faster regression of left ventricular hypertrophy. The hemodynamic performance of stentless porcine valves was similar to that of aortic homografts, nevertheless the aortic homografts preserved in antibiotic solution offered a faster regression of left ventricular hypertrophy during the same period of time.

A novel comparison of stentless versus stented valves in the small aortic root

Background: Previous studies have compared prosthetic valves on the basis of industry-labeled valve sizes. Unfortunately, the relationship between the labeled size and the true measured external or internal diameter differs between valve manufacturers. Therefore hemodynamic comparisons between prosthetic valves are inaccurate if based solely on industry-labeled valve sizes. Methods: We have previously demonstrated that the internal diameter of a 21-mm Carpentier-Edwards pericardial stented valve is similar to that of a 25-mm Toronto stentless porcine valve. Therefore we chose to compare postoperative hemodynamics in patients who received 19-, 21-, or 23-mm Carpentier-Edwards pericardial stented valves (inner diameter 18-22 mm, n = 69) with those in patients who received 23- or 25-mm stentless porcine valves (internal diameter 19-21 mm, n = 41). Results: Patients in the Carpentier-Edwards group were more likely to be elderly and more likely to require concomitant revascularization. Operative mortality was lower in the stentless porcine valve group (0% vs 9%, P = .06). Hospital stay and ventilation requirements were shorter in the stentless porcine valve group. Postoperative hemodynamics were similar in the two groups. Conclusions: These data provide evidence that stentless and stented valves have similar hemodynamic profiles in the small aortic root when matched on true measured internal diameters. The clinical benefit of the stentless porcine valve may be due to patient selection or the lack of a rigid stent in the small aortic root, but it is not due to hemodynamic superiority over stented aortic valves of similar sizes. (J Thorac Cardiovasc Surg 1999;117:431-8)