Increase In Effective Orifice Area Research Articles

A Novel System for Transcatheter Aortic Valve Implantation: First-in-Man Study

Transcatheter aortic valve implantation (TAVI) has become a therapeutic treatment for severe symptomatic patients with aortic stenosis. This study aimed to test a novel transcatheter aortic self-expandable bioprosthesis-the ScienCrown system (Lepu Medtech Inc., Beijing, China)-and evaluate the safety of the new device during TAVI. ScienCrown aortic valve implantation was performed on 10 patients. Clinical assessment was performed at baseline, post procedure, and after 1year. Clinical outcomes and adverse events were assessed according to Valvular Academic Research Consortium-3 criteria. The mean age was 75.30 ± 4.78years with a mean Society of Thoracic Surgeons score of 4.64 ± 3.23%. Device success was achieved in all patients (80% transfemoral, 20% transapical). After 1year, there were no deaths, disabling strokes, myocardial infarctions, conversions to surgery, or major procedure-related complications. New pacemaker implantation was required in one patient (10%). ScienCrown implantation resulted in a reduction in mean valve gradient (63.00 ± 18.84 to 9.67 ± 4.97mm Hg, p <0.001) and an increase in effective orifice area (0.57 ± 0.20 to 2.57 ± 0.59cm2, p <0.001) at 1year. Paravalvular leak was absent in 9 patients (90%), and there was a trace in one patient (10%). All patients were in New York Heart Association class I to II at a mean follow-up of 1year. The experience showed that ScienCrown transcatheter aortic valve system was safely and successfully implanted for treatment of severe symptomatic aortic stenosis. The newer-generation device affords a stable implantation while providing optimal hemodynamic performance.

Comparison of a novel self-expanding transcatheter heart valve with two established devices for treatment of degenerated surgical aortic bioprostheses

AimsThis study was performed to compare haemodynamic properties of a novel transcatheter heart valve (THV) with two established valve technologies for treatment of failing surgical aortic bioprosthetic valves (SAV). The ALLEGRA THV has been recently described with a proven safety and performance profile.Methods and resultsThe study was designed as a retrospective, single-centre study investigating 112 patients (77.7 ± 7.1 years, 53.8% female, STS score 6.8 ± 5.8% and logEuroSCORE I 27.4 ± 16.1%) with failing SAV. Patients were treated with the ALLEGRA THV (NVT, n = 24), the CoreValve/EvolutR (MTD, n = 64) or the Edwards Sapien/Sapien XT/Sapien 3 (EDW, n = 24). Adverse events, haemodynamic outcomes and patient safety were analysed according to VARC-3 definitions. Overall procedural success was high (94.6%), even though 58.9% of the treated SAV were classified as small (true inner diameter < 21 mm). After treatment, the mean pressure gradient was significantly reduced (baseline: 33.7 ± 16.5 mmHg, discharge: 18.0 ± 7.1 mmHg), with a corresponding increase in effective orifice area (EOA). The complication rates did not differ in between groups. There was a trend to lower mean transvalvular gradients after implantation of self-expanding THV with supra-annular valve function, despite a higher frequency of smaller SAVs in the NVT and MTD group. Additionally, comparison between NVT and MTD revealed statistically lower transvalvular gradients (NVT 14.9 ± 5.0 mmHg, MTD 18.7 ± 7.5 mmHg, p = 0.0295) in a subgroup analysis.ConclusionsValve-in-valve (ViV) treatment of failing SAV with supra-annular design like the ALLEGRA THV resulted in favourable haemodynamic outcomes with similar low clinical event rates and may therefore be an interesting alternative for VIV TAVI.Graphical abstract

Abstract 13570: Quantitative 3D Echocardiographic Predictors for Risk Stratification and Improved Management of Congenital Mitral Valve Disease

Background: Congenital mitral valve disease (CMVD) presents major challenges regarding medical and surgical management. Three dimensional echocardiography (3DE) allows precise delineation of area tracing from cross-sectional planes for more precise measurements and outcome analysis. However, there are no available data to inform clinicians on how 3DE can help guide management. We hypothesized that quantitative 3DE measurements can provide improved risk stratification and guide management of CMVD. Methods and Results: Demographic, procedural and outcome data were obtained for all 183 children who underwent MV reconstruction for CMVD from 2002 to 2017. 92 patients had mitral stenosis (MS), 68 mitral regurgitation (MR), and 23 mixed disease (MD). 13 patients (7%) died. MD patients had higher rates of mortality, reoperation, and valve replacement. Quantitative 3DE measurements of the effective orifice area (EOA) and vena contracta regurgitant area (VCRA) were determined preoperatively and before discharge. Changes from baseline in EOA and VCRA were significant independent predictors of reoperation with excellent area under the curve (AUC) values (EOA: AUC = 0.888; VCRA: AUC = 0.962; both P&lt;0.001). As shown in Figure 1, decision analysis revealed that an increase in EOA&lt;30% for patients with MS is associated with 76% risk of reoperation (HR=11.4; 95% CI: 3.4-37.8; P&lt;0.001), whereas a decrease in VCRA &lt;40% for MR patients is associated with 93% risk of reoperation (HR=18.1; 95% CI: 2.3-142; P=0.006). Comparison of the AUC indicated that the change in EOA is a significantly stronger predictor of reoperation than change in mean gradients (MG; P=0.018; DeLong’s test). Conclusions: Reconstructive surgery for CMVD can be performed with good outcomes. 3DE EOA and VCRA aids in postoperative clinical and surgical management. Further, 3DE is more predictive of patient outcomes than 2DE measurements of MG. Thus, we now incorporate 3DE EOA and VCRA into clinical decision making.

Effective Orifice Area during Exercise in Bileaflet Mechanical Valve Prostheses

The aims of this study were to investigate the evolution of the transprosthetic pressure gradient and effective orifice area (EOA) during dynamic bicycle exercise in bileaflet mechanical heart valves and to explore the relationship with exercise capacity. Patients with bileaflet aortic valve replacement (n=23) and mitral valve replacement (MVR; n=16) prospectively underwent symptom-limited supine bicycle exercise testing with Doppler echocardiography and respiratory gas analysis. Transprosthetic flow rate, peak and mean transprosthetic gradient, EOA, and systolic pulmonary artery pressure were assessed at different stages of exercise. EOA at rest, midexercise, and peak exercise was 1.66±0.23, 1.56±0.30, and 1.61±0.28cm2, respectively (P=.004), in aortic valve replacement patients and 1.40±0.21, 1.46±0.27, and 1.48±0.25cm2, respectively (P=.160), in MVR patients. During exercise, the mean transprosthetic gradient and the square of transprosthetic flow rate were strongly correlated (r=0.65 [P<.001] and r=0.84 [P<.001] for aortic valve replacement and MVR, respectively), conforming to fundamental hydraulic principles for fixed orifices. Indexed EOA at rest was correlated with exercise capacity in MVR patients only (Spearman ρ=0.68, P=.004). In the latter group, systolic pulmonary artery pressures during exercise were strongly correlated with the peak transmitral gradient (ρ=0.72, P<.001). In bileaflet mechanical valve prostheses, there is no clinically relevant increase in EOA during dynamic exercise. Transprosthetic gradients during exercise closely adhere to the fundamental pressure-flow relationship. Indexed EOA at rest is a strong predictor of exercise capacity in MVR patients. This should be taken into account in therapeutic decision making and prosthesis selection in young and dynamic patients.

First North American experience with the transfemoral ACURATE-neoTM self-expanding transcatheter aortic bioprosthesis.

Transcatheter aortic valve implantation (TAVI) has become a therapeutic alternative for patients presenting with severe symptomatic aortic stenosis and considered at high-surgical risk. Paravalvular leak (PVL), conduction disorders, and coronary obstruction remain unresolved procedure-related complications. The aim of this manuscript was to report the first North American experience with the ACURATE-neoTM aortic bioprosthesis and its ACURATE-TFTM delivery system (Symetis S.A., Ecublens, Switzerland). Transfemoral ACURATE-neoTM aortic valve implantation was performed in 20 patients. Clinical and echocardiographic assessment was performed at baseline, postprocedure and at least 30 days. Outcomes were assessed according to valvular academic research consortium (VARC-2) criteria. The mean age was 82.7 ± 7.0 years with a mean logistic-EuroSCORE-II of 5.0 ± 2.9% and Society of Thoracic Surgeons score of 4.7 ± 2.3%. Device success was achieved in all patients. The mean distance between the aortic-annulus and the left main coronary artery ostium was 14.3 ± 3.2 mm, and eight (40%) patients had <12 mm. At 30 days, there were no deaths, conversions to surgery, or major procedure-related complications. New-pacemaker implantation was required in one (5.3%) patient. ACURATE-neoTM implantation resulted in a significant reduction in mean transvalvular gradient (49.9 ± 15.8 to 9.7 ± 5.7 mm Hg, P < 0.0001) and increase in effective-orifice area (0.65 ± 0.16 to 1.83 ± 0.36 cm2 , P = 0.001) at hospital discharge. Paravalvular leak was absent in four (20%) patients, trace in nine (45%) patients, and mild in seven (35%) patients. Hospital discharge occurred at a mean of 7.0 ± 4.5 days, and all patients were in NYHA class I-II at a mean follow-up of 8.6 ± 2.3 months. The present initial North American experience shows that the ACURATE-neoTM aortic bioprosthesis was safely and successfully implanted by transfemoral approach. The special design of this newer-generation device affords a stable and predictable implantation, while providing optimal hemodynamic performance with a relatively low rate of PPI. © 2016 Wiley Periodicals, Inc.

A MATCHED-PAIRED COMPARATIVE ANALYSIS OF THE HEMODYNAMICS OF THE TRIFECTA AND PERIMOUNT AORTIC BIOPROSTHESES

A MATCHED-PAIRED COMPARATIVE ANALYSIS OF THE HEMODYNAMICS OF THE TRIFECTA AND PERIMOUNT AORTIC BIOPROSTHESES

An In Vitro Model of Aortic Stenosis for the Assessment of Transcatheter Aortic Valve Implantation

A significant number of elderly patients with severe symptomatic aortic stenosis are denied surgical aortic valve replacement (SAVR) because of high operative risk. Transcatheter aortic valve implantation (TAVI) has emerged as a valid alternative to SAVR in these patients. One of the main characteristics of TAVI, when compared to SAVR, is that the diseased native aortic valve remains in place. For hemodynamic testing of new percutaneous valves and clinical training, one should rely on animal models. However, the development of an appropriate animal model of severe aortic stenosis is not straightforward. This work aims at developing and testing an elastic model of the ascending aorta including a severe aortic stenosis. The physical model was built based on a previous silicone model and tested experimentally in this study. Experimental results showed that the error between the computer-aided design (CAD) file and the physical elastic model was &lt;5%, the compliance of the ascending aorta was 1.15 ml/mm Hg, the effective orifice area (EOA) of the stenotic valve was 0.86 cm2, the peak jet velocity was 4.9 m/s and mean transvalvular pressure gradient was 50 mm Hg, consistent with as severe. An EDWARDS-SAPIEN 26 mm valve was then implanted in the model leading to a significant increase in EOA (2.22 cm2) and a significant decrease in both peak jet velocity (1.29 m/s) and mean transvalvular pressure gradient (3.1 mm Hg). This model can be useful for preliminary in vitro testing of percutaneous valves before more extensive animal and in vivo tests.

Single-centre experience with next-generation devices for transapical aortic valve implantation†

Transcatheter aortic valve implantation (TAVI) has become an established procedure in patients with aortic stenosis and high surgical risk. Experience with first-generation transcatheter heart valves (THVs) is broad but limitations, e.g. paravalvular regurgitation, have been demonstrated. Much hope rests on the recently Conformité Européenne mark approved next-generation devices to improve results in these patients. However, apart from the initial approval studies, clinical data with these new devices are still scarce. We aimed to assess short-term outcomes of 200 consecutive patients who underwent transapical TAVI with next-generation THV at our institution. Transapical TAVI was performed in 200 consecutive patients 80.5±6.7 years old (38.5% female) at high surgical risk (log EuroSCORE 20.2±16.5%). Devices implanted were the Engager (Medtronic, Inc., Minneapolis, MN, USA; n=50), JenaValve (JenaValve Technology, Munich, Germany; n=88) and Symetis Acurate (Symetis SA, Ecublens, Switzerland; n=62) THV that were selected by the heart team on an individual basis. Data at baseline, during the procedure and follow-up were analysed according to standardized Valve Academic Research Consortium end points. Median follow-up was 219 days. Implantation was successful in 96.5% of cases. Valve function improved significantly with an increase in effective orifice area from 0.8±0.4 to 1.8±0.3 cm2 and a reduction in mean transvalvalvular gradients from 34.0±17.0 to 11.2±5.4 mmHg. Paravalvular regurgitation was none or trace in 70.3% of patients, Grade 1 in 26.1%, and Grade 2 in 3.5%. No patients developed aortic regurgitation>Grade 2. Major access site complications occurred in 6.5%, major stroke in 1.5% and stage-3 kidney injury in 2.5% of patients. A permanent pacemaker was implanted in 20.5% of patients overall and in 8.0% for a complete heart block. At 30-day follow-up 72.8% of patients were in New York Heart Association class I or II (10.5% at baseline). Overall survival was 91.5% at 30 days and 73.9% at 1 year. In a real-world clinical setting, next-generation transapical THV yielded positive haemodynamic results. The incidence of relevant paravalvular regurgitation was scarce in this group and clinical outcomes were encouraging during short-term follow-up. Long-term follow-up is required to investigate the durability of these new devices.

Load independent impairment of reverse remodeling after valve replacement in hypertensive aortic stenosis patients

BackgroundWe evaluated the impact of hypertension on the left ventricular mass regression in aortic stenosis after aortic valve replacement. MethodsWe prospectively studied 135 patients with severe aortic stenosis at baseline and 1year after surgery. In 32 patients we analyzed myocardial gene expression of collagen types I and III, connective tissue growth factor, transforming growth factor-β1, metalloproteinase-2 and its tissue inhibitor and compared its levels vs controls. ResultsSeventy-six patients (56.3%) had a history of hypertension. Hypertensive patients were older, had higher Euroscore-II and NYHA class, with no differences in stenosis severity. At 1year follow-up there was a median decrease of mass index of 14.2% (P25–75: −4.3%–30.4%; p<0.001). Mass regression was significantly higher in patients without hypertension, with a median decrease of 25.9% (P25–75: 12.0%–38.7%) vs 5.4% (P25–75: −12.5%–20.1%; p=0.001), despite similar increase in effective orifice area and no differences in valvuloarterial impedance. After 1year, higher baseline left ventricular mass index (p=0.005) and the absence of hypertension (p=0.002) or diabetes (p=0.041) were the only independent predictors of mass regression higher than the median. Comparing with controls, aortic stenosis patients had an increased expression of collagen types I and III, but only hypertensive patients had higher relative expression of collagen type I vs III. In hypertensive patients TIMP2 expression was up-regulated and correlated with higher baseline left ventricular mass index (r=0.61; p=0.020). ConclusionsIn aortic stenosis, hypertension impairs mass regression one year after valve replacement, independently of total afterload. Differences in the expression of extracellular matrix remodeling genes might contribute to this finding.

Comparison of Transcatheter and Surgical Aortic Valve Replacement in Severe Aortic Stenosis: A Longitudinal Study of Echocardiography Parameters in Cohort A of the PARTNER Trial (Placement of Aortic Transcatheter Valves)

This study sought to compare echocardiographic findings in patients with critical aortic stenosis following surgical aortic valve replacement (SAVR) or transcatheter aortic valve replacement (TAVR). The PARTNER (Placement of Aortic Transcatheter Valves) trial randomized patients 1:1 to SAVR or TAVR. Echocardiograms were obtained at baseline, discharge, 30 days, 6 months, 1 year, and 2 years after the procedure and analyzed in a core laboratory. For the analysis of post-implantation variables, the first interpretable study (≤6 months) was used. Both groups showed a decrease in aortic valve gradients and increase in effective orifice area (EOA) (p < 0.0001), which remained stable over 2 years. Compared with SAVR, TAVR resulted in larger indexed EOA (p = 0.038), less prosthesis-patient mismatch (p = 0.019), and more total and paravalvular aortic regurgitation (p < 0.0001). Baseline echocardiographic univariate predictors of death were lower peak transaortic gradient in TAVR patients, and low left ventricular diastolic volume, low stroke volume, and greater severity of mitral regurgitation in SAVR patients. Post-implantation echocardiographic univariate predictors of death were: larger left ventricular diastolic volume, left ventricular systolic volume and EOA, decreased ejection fraction, and greater aortic regurgitation in TAVR patients; and smaller left ventricular systolic and diastolic volumes, low stroke volume, smaller EOA, and prosthesis-patient mismatch in SAVR patients. Patients randomized to either SAVR or TAVR experience enduring, significant reductions in transaortic gradients and increase in EOA. Compared with SAVR, TAVR patients had higher indexed EOA, lower prosthesis-patient mismatch, and more aortic regurgitation. Univariate predictors of death for the TAVR and SAVR groups differed and might allow future refinement in patient selection. (THE PARTNER TRIAL: Placement of AoRTic TraNscathetER Valve Trial; NCT00530894).

Abstract 8990: Bivalvular Transcatheter Treatment of Patients with Concomitant Aortic Stenosis and Mitral Regurgitation

Transcatheter techniques to treat severe aortic stenosis (AS) or significant mitral regurgitation (MR) in patients deemed at high surgical risk have shown to be safe and efficacious in either clinical entity. For AS, transcatheter aortic valve replacement (TAVR) using the Sapien/Sapien XT prosthesis (Edwards Lifesciences) via transfemoral (TF) or transapical (TA) access or the CoreValve prosthesis (Medtronic) via TF access has become a viable therapeutic option, whereas in MR, considerable clinical experience has been gained with transvenous/transseptal implantation of the MitraClip (MC) device (Abbott Vascular). To date, little information is available on transcatheter treatment for both AS and MR in the same patient. By May 2011, 263 TAVR and 233 MC procedures had been performed at our center. Eleven patients (78 ± 6 years, 9 men [82%]) underwent both TAVR and MC implantation. In the first 8 patients treated, TAVR (5 TA, 3 TF) preceded MC by a median of 84 (range, 4 to 348) days, whereas in the last 3 patients TAVR (1 TA, 2 TF) and, subsequently, MC were performed in a single session. All TAVR procedures (7 Sapien [n=4]/Sapien XT [n=3], 4 CoreValve prostheses) were successfully completed, resulting acutely in a significant increase in effective orifice area from 0.90 ± 0.12 to 1.82 ± 0.58 cm 2 ( P = 0.0114) and a significant decrease in mean transaortic pressure gradient from 22 ± 10 to 7 ± 2 mmHg ( P = 0.0077). MC implantation (1 clip, n=8; 2 clips, n=2; 3 clips, n=1) succeeded in reducing MR severity to &lt;=2+ in 10 patients (MR 1+, n=5; MR 2+, n=5); in 1 patient, MR severity remained at 3+ despite placement of 2 clips. Permanent pacemaker implantation was required in 5 patients (4 Sapien/Sapien XT, 1 CoreValve); 1 patient sustained a stroke 19 days after bivalvular treatment in a single session. Post TAVR, no patient had transvalvular aortic regurgitation (AR); minor (grade 1) paravalvular AR was present at discharge in 8 patients. Patients were followed for a median of 210 (range, 69 to 398) days. Two patients (18%; 95% CI, 2% to 52%) died of persistent cardiac decompensation at 73 and 398 days after successful bivalvular treatment. We conclude that bivalvular transcatheter treatment of concomitant AS and MR is feasible, efficacious and safe, even if performed in a single session.

Long-Term Results After Aortic Valve Replacement With the Bravo 400 Stentless Xenograft

This study was undertaken to evaluate the long-term clinical and echocardiographic outcome after aortic valve replacement with the Bravo Cardiovascular Model 400 stentless xenograft. Between February 1992 and January 1994, 67 patients underwent aortic valve replacement with the Bravo 400 bioprosthesis. The valvular pathology was aortic stenosis in 36 patients (53.7%), aortic insufficiency in 17 patients (25.4%), and mixed lesion in 14 patients (20.9%). Mean follow-up time was 9.8 +/- 2.73 years and median follow-up time was 11 years. Cumulative follow-up time was 659 patients-years and was 94% complete. No early deaths were observed. Overall survival estimates at 11 years were 74.71% +/- 5.47%. The actuarial freedom from valve-related death at 11 years was 91.04% +/- 3.84%; from cardiac-related death at 11 years it was 87.95% +/- 4.29%; and from noncardiac death at 11 years it was 85.14% +/- 4.58%. Eleven-year Kaplan-Meier survival of patients younger than 65 years was 90.91% +/- 6.13% versus 66.08% +/- 7.38% for older patients (p = 0.0307, log-rank test). The actuarial freedom from all valve-related morbidity and mortality at 11 years was 80.3% +/- 5.4%. The mean transvalvular gradient decreased significantly after aortic valve replacement with a corresponding increase in effective orifice area. Left ventricular mass index at 10-year follow-up was 68.5% of the preoperative value. The Bravo Cardiovascular Model 400 stentless xenograft has provided good clinical and hemodynamic results up until 11 years of follow-up.

Aortic Valve Replacement With the Freestyle Stentless Bioprosthesis

Background —Stentless aortic valves were designed to provide a more physiological flow pattern and lower transvalvular gradient, which may have an important bearing on postoperative left ventricular function and remodeling. In this study, we prospectively analyzed the 5-year clinical results with the Freestyle valve (Medtronic, Inc) and its hemodynamic performance by serial echocardiography. Methods and Results —Between January 1993 and August 1997, 95 patients with a mean age of 75 years underwent aortic valve replacement with the Freestyle prosthesis. Sixty-four percent of patients received valves ≤23 mm, and 37% had concomitant coronary artery bypass grafting. Average follow-up was 44±18 months (mean±SD), and echocardiography was performed preoperatively, at discharge, at 3 to 6 months, and annually thereafter. The 30-day operative mortality rate was 3%, with an overall actuarial survival rate of 80±6% (mean±SEM) at 5 years. Of the 10 late deaths, only 2 were cardiac related, thereby yielding a freedom from cardiac mortality of 94±3% after 5 years. No patient required reoperation on the aortic valve for any reason, including structural degeneration, nonstructural dysfunction, or prosthetic valve endocarditis. There were 9 thromboembolic and 3 anticoagulant-related bleeding events, none of which was fatal. The actuarial freedom from valve-related morbidity and mortality was 79±4% at 5 years. Hemodynamically, the mean transvalvular gradient significantly decreased after valve replacement and was reduced further by 41% by 6 months with a corresponding increase in effective orifice area. Left ventricular mass index fell to 75% of the preoperative value by 2 years. Conclusions —The Freestyle stentless valve can be implanted safely in the elderly with excellent midterm clinical results. It has superb hemodynamics in terms of residual transvalvular gradient, effective orifice area, and regression of left ventricular hypertrophy.

Fifth-year hemodynamic performance of the prima stentless aortic valve

Background. The medium-term hemodynamic performance of stentless valves has not been widely reported, particularly in comparison with in vitro studies. Therefore, we have assessed prospectively the hemodynamics of the Edwards Prima valve in its fifth year after implantation in the aortic position, and compared the results with those at 1 month after implantation and also with in vitro data. Methods. Thirty-five patients (age, 77 ± 6 years; 19 men) were prospectively studied by Doppler echocardiography at 1 month and 52 ± 8 months after implantation of a Prima stentless valve. Valve hemodynamics were assessed by measuring the mean pressure gradient, mean valve resistance, and effective orifice area. Left ventricular systolic function was quantified by ejection fraction, the degree of hypertrophy by ventricular mass index, and the ratio of ventricular wall thickness to cavity radius as a measure of ventricular geometry. Results. With a mean valve size of 24.6 ± 2.2 mm in the fifth year after implantation, the mean pressure gradient was 6.2 ± 3.5 mm Hg, the mean valve resistance, 29 ± 16 dyne · s −1 · cm −5), and the effective orifice area was 2.05 ± 0.50 cm 2. Compared with 1 month after operation, there was a 47% decrease in mean valve resistance ( p = 0.002) and a 39% increase in effective orifice area ( p = 0.001). Furthermore, both effective orifice area and mean valve resistance in the fifth year did not differ from their in vitro counterparts, whereas the left ventricular ejection fraction (0.64 ± 0.14), the left ventricular mass index (119 ± 49 g/m 2), and the ratio of ventricular wall thickness to cavity radius (0.44 ± 0.13) were within the normal range. Conclusions. This study suggests that the Prima valve is a reliable stentless aortic bioprosthesis. This is supported by a favorable medium-term clinical outcome, durable hemodynamic performance, and normal mean values of left ventricular ejection fraction and mass index in the fifth year after implantation.

Stentless Aortic Bioprostheses: Compelling Data From the Second International Symposium

Background. Stentless aortic xenografts are an important addition to the range of prosthetic valves. So far their use has been restricted to a limited number of study centers. This report summarizes the principal findings from the Second International Symposium on Stentless Bioprostheses. Attention is focused on the Toronto SPV and Freestyle valves recently approved by the United States Food and Drug Administration. Methods. Stentless xenografts are used predominantly in elderly patients with aortic stenosis. Implant techniques are more complex than for stented valves, as reflected by longer ischemic and cardiopulmonary bypass times. The valves have been subjected to detailed serial echocardiographic assessment and clinical follow-up. Results. The hemodynamic characteristics resemble those of the aortic homograft. There is a progressive increase in effective orifice area and decrease in transvalvular pressure gradients with time. Left ventricular mass index and wall thickness normalize between 6 and 12 months postoperatively. Left ventricular remodeling is accompanied by improved symptomatic status and a low incidence of valve-related complications. Limited comparative studies suggest important benefits over stented xenografts. Improved hemodynamics may translate into better bioprosthetic durability. Conclusions. Reproducible and reliable implant methods should be taught carefully, but the hemodynamic advantages are substantial. Stentless xenografts are ideal for the elderly patient with aortic stenosis.