The Toronto SPV bioprosthesis: One-year results in 100 patients

Stentless Versus Conventional Xenograft Aortic Valve Replacement: Midterm Results of a Prospectively Randomized Trial

BACKGROUND

The purpose of this study was to analyze the 5- to 8-year clinical results after prospectively randomized stentless versus conventional aortic valve replacement.

METHODS

Two hundred twenty-three patients received stentless (Freestyle or Toronto, n = 127) or conventional stented (CE porcine, n = 96) xenograft aortic valve replacement between March 1996 and March 1999 using a prospectively randomized protocol and were discharged from the hospital. Patient age at operation was 71.8 +/- 6.7 years stentless and 74.9 +/- 4 years stented (p < 0.05). There were no significant differences regarding preoperative morphologic and hemodynamic variables. Aortic annulus diameter indices were comparable at 13.5 mm stentless and 13.6 mm stented. Follow-up after 6.9 +/- 0.8 years is complete for 95.6% of the patients at a total of 1,533 patient-years. Analysis of variance, unpaired t test, univariate (chi2), and survival analysis (log rank) were performed.

RESULTS

Eight-year survival was 78.1% +/- 3.8% stentless versus 66% +/- 4.9% stented (p = 0.04); mean survival was 97 months stentless versus 88 months stented. At most recent follow-up, New York Heart Association functional class was 1.6 +/- 0.6 stentless versus 1.5 +/- 0.7 stented (p = not significant); ejection fraction was 61% +/- 11% versus 61% +/- 8% (p = not significant); transvalvular maximum flow velocity was 23 +/- 9 mm Hg versus 37 +/- 15 mm Hg (p < 0.01). Thrombembolic events occurred in 2 of 7 patients, including 2 of 6 patients suffering major stroke (p = not significant). Most (93%) of the patients were satisfied with the postoperative course, having a significantly improved quality of life.

CONCLUSIONS

Midterm results after xenograft aortic valve replacement are satisfactory. Overall survival is significantly better after stentless aortic valve replacement in this series. However, there was no cause and effect relationship between lower transvalvular pressure gradient. Fewer thrombembolic events and better survival rates were proven.

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

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

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.

European experience with the Mosaic bioprosthesis

OBJECTIVE

The purpose of this study was to prospectively evaluate the clinical and hemodynamic performance of the Mosaic bioprosthesis (Medtronic, Inc, Minneapolis, Minn).

METHODS

The stented porcine bioprosthesis combines the amino-oleic acid antimineralization treatment and the zero-pressure differential fixation technique for improved tissue durability. From February 1994 to May 1999, a total of 561 patients underwent valve replacement with the Mosaic bioprosthesis at 5 centers in Europe: 461 in the aortic and 100 in the mitral position. There were 261 women and 300 men; mean age at implantation was 70 years (range, 23-89 years). Mean follow-up was 2.9 years (range, 0-6.2 years), with a total follow-up of 1710.1 patient-years.

RESULTS

Postoperative mortality was 4.2% per patient-year, including a valve-related mortality of 0.4% per patient-year. The freedom from event rates in the aortic position at 5 years and in the mitral position at 4 years were, respectively, 96.6% +/- 1.1% and 94.9% +/- 3.3% for primary thromboembolism, 96.4% +/- 5.0% and 87.1% +/- 4.8% for antithromboembolic-related hemorrhage, 99.1% +/- 0.5% and 100% for thrombosed prosthesis, 98.8% +/- 1.2% and 100% for structural valve deterioration, 98.8% +/- 0.7% and 100% for nonstructural dysfunction, 98.4% +/- 0.6% and 94.4% +/- 3.8% for endocarditis, and 95.4% +/- 1.6% and 95.3% +/- 3.7% for explant and reoperation. Mean pressure gradient values at 5 years ranged from 7.5 to 15.9 mm Hg in the aortic position and at 4 years from 2.0 to 6.9 mm Hg in the mitral position across all valve sizes.

CONCLUSIONS

Clinical and hemodynamic performance of the Mosaic bioprosthesis were very satisfactory during the first 6 years after clinical introduction.

Hemodynamic and clinical impact of prosthesis-patient mismatch in the aortic valve position and its prevention

Prosthesis-patient mismatch is present when the effective orifice area of the inserted prosthetic valve is less than that of a normal human valve. This is a frequent problem in patients undergoing aortic valve replacement, and its main hemodynamic consequence is the generation of high transvalvular gradients through normally functioning prosthetic valves. The purposes of this report are to present an update on the concept of aortic prosthesis-patient mismatch and to review the present knowledge with regard to its impact on hemodynamic status, functional capacity, morbidity and mortality. Also, we propose a simple approach for the prevention and clinical management of this phenomenon because it can be largely avoided if certain simple factors are taken into consideration before the operation.

The extended Biocor stentless aortic bioprosthesis. Early clinical experience

In the "Extended" Biocor stentless aortic bioprosthesis, supra- and subvalvular extensions to a bovine pericardium ring carry three porcine leaflets. The extensions cover the "non-coronary" sinus of the prosthesis and allow optional enlargement of the aortic root down towards the mitral valve as well as upwards into the aortotomy. Seventy-one patients with this stentless valve (62 with predominantly aortic stenosis, 28 with concomitant CABG) are being prospectively studied. This paper reports follow-up one year after insertion. The upper and lower pericardial extensions were used in 61 and 11 patients, respectively. The average prosthetic valve size was 23.2 +/- 1.6 mm. Early mortality was 7% (5/71); late mortality (4/66, 5%/patient year) was not valve-related. Symptoms of thromboembolism (new neurological defects) occurred in four patients. There was no valve failure or late endocarditis. One year postoperatively the transvalvular mean pressure difference for all valves was 7.9 (3.1-18.4) mmHg. None of the patients had haemodynamically significant aortic regurgitation at follow-up; nine had trivial regurgitation. The "Extended" Biocor stentless bioprosthesis thus has a favourable haemodynamic profile and can be advantageous in elderly patients with narrow aortic roots, and often with thin and/or calcified aortic walls.

Aortic root reconstruction with preservation of native aortic valve and sinuses in aortic root dilatation with aortic regurgitation

BACKGROUND

We assessed the results of a modified technique for aortic root reconstruction including preservation of the native aortic valve and sinuses.

METHODS

A modified technique for reconstruction of the aortic root was devised in which the native aortic sinuses are preserved and remodeled, the diameter of the sinotubular junction is reduced, the ventriculoaortic junction is reinforced with a Dacron prosthesis, and the coronary ostia are reimplanted. Since January 1995, this modified operative technique was performed in 13 patients with a mean age of 54 +/- 21 years. The median grade of aortic regurgitation was 3; in 10 patients it was caused by dilatation of the sinotubular junction, and 3 had additional annuloaortic ectasia.

RESULTS

The aortic crossclamping time was 61 +/- 18 minutes. In-hospital mortality was 2 of 13 (15. 3%) patients, both deaths being related to complications of aortic dissection. In 1 patient aortic regurgitation increased to grade 3, necessitating aortic valve replacement. At a mean follow-up of 2.1 years, the remaining 10 patients had stable aortic valve function with a median grade of regurgitation of 1. The mean New York Heart Association functional class was 1.2.

CONCLUSIONS

Aortic root reconstruction with preservation of the native aortic valve and sinuses allows symmetric reconstruction of the aortic sinuses and adaptation of the diameters of the sinotubular and ventriculoaortic junctions, thus optimizing aortic valve function. Moreover, it prevents contact of the aortic valve leaflets with the Dacron graft, which may enhance the durability of the repair.

Hemodynamics and left ventricular mass regression following implantation of the Toronto SPV stentless porcine valve

Stentless tissue valves may provide more favorable hemodynamics than conventional stented valves. Hemodynamic findings from a large multicenter trial have not been previously reported. The present report describes the hemodynamic findings from a multinational, multicenter study after implantation of the Toronto SPV valve. A total of 577 patients underwent aortic valve replacement with the Toronto SPV valve at 12 sites in 3 countries. Echocardiograms were recorded in the early postoperative period, 3 to 6 months after surgery, 1 year after surgery, and yearly thereafter, with follow-up to 3 years. Gradients decreased and effective orifice area increased in the months after surgery. One year after surgery, mean gradient for valve sizes 20 to 22, 23, 25, 27, and 29 mm was 7.3 +/- 4.4, 7.4 +/- 4.5, 6.1 +/- 3.3, 4.9 +/- 2.4, and 4.0 +/- 2.1 mm Hg, respectively; effective orifice area was 1.3 +/- 0.7, 1.5 +/- 0.5, 1.7 +/- 0.4, 2.0 +/- 0.4, and 2.4 +/- 0.6 cm2, respectively. There was a very low prevalence of significant aortic regurgitation at all time periods. There was significant left ventricular (LV) mass regression between the early and 3- to 6-month periods and between the 3- to 6-month and 1-year postoperative periods. The Toronto SPV valve has an excellent hemodynamic profile supported by significant regression of LV hypertrophy in the year after implantation. Data through 3 years demonstrates maintenance of low gradients and freedom from significant aortic regurgitation.

The Cryolife-O'Brien stentless aortic porcine xenograft valve

BACKGROUND

The advantageous design of the Cryolife-O'Brien stentless porcine aortic valve permits specific quick, easy, supravalvular implantation using single layer continuous 3-0 polypropylene suture. The advantages, contraindications, and implantation errors to avoid are detailed. The use of this valve for aortic valve replacement in the elderly population has been directed to proving its efficacy and establishing its grounds for durability while maintaining all of the advantages of a stentless tissue valve.

METHODS

From December 1992 to September 1998, this valve was used in 240 patients (mean age 73 years: 15% > 80 years), 45% receiving associated coronary artery grafting (2.4 grafts per patient). Left ventricular (LV) myomectomy was necessary in 12% of patients. Detailed postoperative follow-up (100%) analysis included 650 serial echocardiographic studies.

RESULTS

The 30-day mortality was low at 1.2% (3 deaths of 240 elderly patients). Ten patients had late mortality (1.5 months to 5 years), all nonvalve related. No structural failure and one only explant for endocarditis have occurred. Echocardiographic analyses have shown low mean transvalvular gradients in relationship to time (8.18 mmHg at 18 months) and to valve size (8.52 mmHg for a 23-mm host aortic annulus). Incompetence has been zero or a trace in 97% of the patients at 21/2 years. No patient over the 6 years shows valve deterioration.

CONCLUSION

Six years of experience with this stentless valve in 240 elderly patients has revealed the many advantages of this safe, composite, and truly stentless device that is assembled without the need for Dacron support. Excellent sustained hemodynamics with low gradients, minimal regurgitation, and a good effective orifice have been coupled with low immediate mortality, no intrinsic valve failure, and one explant for endocarditis. Marked LV regression and minimal late valve-related complications confirm the safety and advantages of this stentless valve.

Medtronic Freestyle aortic root bioprosthesis: Implant techniques

BACKGROUND

The Medtronic Freestyle aortic root bioprosthesis is a complete porcine aortic root to allow implantation (1) as a subcoronary valve replacement by removing graft sinus aorta, (2) as a cylinder with the sinotubular junction intact within the aorta (root inclusion), or (3) as a complete aortic root replacement. The choice among the three implant techniques depends on surgeon preference or upon the pathology encountered. The advantages and differences among the three implant techniques are examined.

METHODS

The Medtronic Freestyle bioprosthesis was implanted in 1163 patients in a Food and Drug administration (FDA) clinical trial between August 1992 and October 1997. There were 21 centers in the international trial using a single data repository. Clinical data was collected prior to and at operation, at 3 to 6 months and annually. The data were compiled and statistical analysis performed at the data center.

RESULTS

Patients having subcoronary valve implants were older (80% > 65 years) and aortic occlusion time was about 20 minutes less than the other methods. Patients having aortic root replacement presented with more aortic valve insufficiency (20%). Pathology of the aortic root and ascending aorta requiring repair was 26%, and larger (27 mm) valves were used in 40% of patients. Risk of operation was lowest (5.0%) with subcoronary valve implants and highest (11.7%) with root replacement technique. Thromboembolism was higher, early and late, with root inclusion (3.0, 3.9%/patient per year) and root replacement (3.2, 3.0%/patient per year) than for subcoronary implants (1.8, 1.6%/patient per year). There were more patients taking warfarin at the 4-year point with root inclusion (20%) or root replacement techniques (24%) than among patients having subcoronary implants (14%). Explants of the valve occurred in 2% of patients, none of whom had aortic root replacement.

CONCLUSIONS

The Medtronic Freestyle bioprosthesis is an effective and versatile device for replacement of the aortic valve. It offers implant techniques that can treat the aortic root pathology encountered at surgery and allows the operation to proceed according to surgeon preference.

Clinical and hemodynamic comparison of the Medtronic Freestyle and Toronto SPV stentless valves

The excellent hemodynamics of stentless valves have been observed by numerous investigators. With the recent release of the Toronto SPV (stentless porcine valve) and the Medtronic Freestyle stentless valves in North America, it is appropriate to now compare the clinical and hemodynamic performance of these devices. We analyzed the results of 995 patients who underwent aortic valve replacement (AVR) with either of the two valves; in all cases a subcoronary implant technique was used. There were important differences in the preoperative characteristics for the two groups: Medtronic Freestyle patients were notably older than the Toronto SPV patients (70.7+/-8.6 vs 61.8+/-11.1 years, p < 0.001) and were markedly more symptomatic (p < 0.0001). In the Toronto SPV group, most patients had New York Heart Association (NYHA) Class II (41.5%) or Class III (44.7%) symptoms preoperatively, while in the Freestyle group, 61.5% were in Class III and 12.5% were in Class IV. There were no notable differences in mortality or morbidity for the two groups. Both devices demonstrated a meaningful decrease in mean gradient and a corresponding increase in effective orifice area (EOA). Furthermore, the indexed EOA (EOA/body surface area [BSA]) was > 1cm2/m2 for all valves indicating there was no patient-prosthetic mismatch. There was a meaningful decrease in left ventricular (LV) mass as well as LV mass index (LVMI) for both devices up to 3 years postoperatively. Our data indicate that there were no differences in clinical outcome or hemodynamic performance of these two valves. Both devices offer excellent results with normalization of LV function.

Aortic valve replacement with the Biocor PSB stentless xenograft

BACKGROUND

The midterm clinical results after aortic valve replacement with the Biocor PSB stentless xenograft on all patients operated between October 1992 and October 1996 were reviewed.

METHODS

One hundred six patients, aged 70+/-6 years, had aortic valve replacement for aortic stenosis (67%), regurgitation (11%), or both (22%). Associated procedures were done in 49 patients (46%), including coronary artery bypass in 30 patients, mitral valve repair/replacement in 16, and ascending aorta replacement in 5 patients. Aortic cross-clamp and cardiopulmonary bypass times were 96+/-24 and 129+/-31 minutes, respectively.

RESULTS

There were 3 (3%) early deaths due to low output (2 patients) and cerebrovascular accident (1 patient). Follow-up of survivors ranged from 6 to 66 months (mean, 39+/-14 months). Survival was 94%+/-2% and 90%+/-3% at 1 and 5 years. There were 5 late deaths due to cardiac cause (2), cancer (2), and pulmonary embolism (1 patient). No patient had structural valve deterioration, whereas 100% and 95%+/-3% were free from valve-related events at 1 and 5 years. There were two reoperations due to narrowing of the left coronary ostium and endocarditis, with an actuarial freedom from reoperation of 99%+/-1% and 98+/-1% at 1 and 5 years, respectively. Functional results demonstrated a mean peak transprosthetic gradient of 16+/-12 mm Hg, with only 1 patient (1%) with a 55 mm Hg gradient. No cases of valve regurgitation greater than mild were recorded at follow-up. Assessment of New York Heart Association functional class demonstrated a significant improvement (2.9+/-0.6 versus 1.4+/-0.7; p=0.01). All patients were free from anticoagulation.

CONCLUSIONS

Aortic valve replacement using the Biocor PSB stentless xenograft offers excellent midterm survival, negligible valve deterioration, and a very low rate of valve-related events, which are comparable to estimates reported with other models of stentless xenografts and currently available stented xenografts. Hemodynamic performance is favorable and quality of life satisfactory.

Aortic valve replacement with medtronic freestyle bioprosthesis: operative technique and results

OBJECTIVE

This study evaluates the initial results for safety and efficacy of aortic valve replacement (AVR) using the Medtronic Freestyle Bioprosthesis.

METHODS

One hundred three patients underwent AVR with the Medtronic Freestyle Bioprosthesis over a 40-month period. There were 59 male and 44 female patients with a mean age of 74 years (range 36 to 88 years). Valve size ranged from 19 to 27 mm, and all valves were implanted using a freehand subcoronary technique. Anticoagulation with coumadin was only used for atrial fibrillation. Aspirin was given to patients with associated coronary artery disease. Echocardiography to assess transvalvular pressure gradient and effective valve orifice area was performed at discharge, 3 to 6 months, 1 year, and then annually.

RESULTS

There were 4 (3.9%) deaths within 30 days of operation and 5 (4.9%) late deaths. Two (1.9%) deaths were valve-related, one from commissural dehiscence and one from bacterial endocarditis. Three (2.9%) deaths, two early and one late, were from other cardiac causes. The remaining deaths were from noncardiac causes. Five (4.9%) patients suffered a thromboembolic event, two had permanent neurological deficits, two had transient neurological events, and one had coronary artery occlusion. Mean transvalvular gradient assessed by echocardiography was low at all time intervals: discharge (12.8 mmHg), 3 to 6 months (11.3 mmHg), 1 year (12.0 mmHg), and 2 years (11.6 mmHg). Mean effective valve orifice area was good at all time intervals: discharge (1.4 cm2), 3 to 6 months (1.5 cm2), 1 year (1.6 cm2), and 2 years (1.6 cm2). Of the 38 patients assessed by echocardiography at 1 year, 33 (87%) had no or trivial valve incompetence and the remainder had mild valve incompetence.

CONCLUSIONS

Aortic valve replacement with the Medtronic Freestyle Bioprosthesis has a low incidence of early valve-related mortality and thromboembolism. The bioprosthesis demonstrates good hemodynamic performance even in small diameters and is particularly well suited for older patients and the small aortic root.

Complete morphologic and functional resolution of endocarditis of a Toronto stentless porcine bioprosthesis: a study by serial transesophageal echocardiography

Prosthetic valve endocarditis is a serious complication after valve replacement with an incidence of 0.8% for both mechanical and bioprosthetic valves. The new Toronto stentless porcine valve (SPV) for aortic replacement offers promising early results in hemodynamics and a low incidence of valve-related complications. The yearly incidence of bacterial endocarditis was reported to be 1% to 1.5%. Though complications such as a perivalvular abscess or anular dehiscence require immediate surgery, a conservative management of infective endocarditis may be possible in carefully selected cases. This is the case of a patient with late prosthetic valve endocarditis of a Toronto SPV bioprosthesis, who, in spite of large vegetations on all three valve cusps, responded well to conservative treatment. This response was monitored through repeated transesophageal echocardiographic studies (TEE), which documented complete functional recovery of the valve.

Technique for reconstruction of the sinotubular junction

Correct geometric relationships between the annulus and sinotubular junction during stentless valve implantation are critical to minimize the development of insufficiency. Some patients with aortic valve disease have dilatation of the sinotubular junction and are unable to have a stentless valve placed by standard techniques. We recently encountered such a patient and reconstructed the sinotubular junction by aortic crenation. Multiple interrupted plicating sutures were used to reduce the aorta from a diameter of 42 mm to 28 mm. This method allows tailoring of the aorta to appropriate size by varying the number of crenating sutures.

Carpentier-Edwards bioprosthesis. Experiences of 17 years with analysis of risk factors of early mortality

Isolated aortic (AVR, N = 71), mitral (MVR, N = 103), tricuspid (TVR, N = 3), pulmonary (PVR, N = 8), combined AVR + MVR (N = 4), or combined MVR + TVR (N = 2) valve replacement with a Carpentier-Edwards porcine bioprosthesis was performed in 191 patients between 1979 and 1986. Mean age was 56.9 +/- 17 (range 5-80) years in the total cohort. The operative mortality rates were 5.6% and 8.7%, respectively, for AVR and MVR. Mean observation time was 8 +/- 4.2 (0-16.7) years (total = 1.467 patient-years). Follow-up was 100% complete with respect to mortality. There were 78 late deaths (44%). Actuarial survival rates at 5 and 10 years were 73.2 +/- 5.2 and 52.1 +/- 6.6 for AVR and 76.7 +/- 4.2 and 61.6 +/- 4.8 for MVR. Coronary artery disease, concomitant coronary artery bypass grafting and emergency operation were significant risk factors of early mortality (p < 0.05). Postoperatively, sepsis and multiorgan failure were associated with early mortality (p < 0.05). The 10-year actuarial freedom from structural deterioration for AVR was 89 +/- 4.6 and 76.4 +/- 4.3 for MVR. It is concluded that structural valve failure is the most important factor that adversely affects the performance of Carpentier-Edwards bioprosthesis.

Hemodynamic benefits of the Toronto Stentless Valve

We report on 254 consecutive patients (170 male, 84 female) undergoing aortic valve replacement with the Toronto SPV Stentless Valve (St. Jude Medical, Inc., St. Paul, Minn.). Mean age (+/- standard deviation) was 62.1 +/- 11.6 years. Three patients (1%) received sizes 21 or 22 mm, 24 (9%) received size 23 mm, and 227 patients (89%) received sizes 25, 27, or 29 mm. Serial echocardiography was used to assess valve performance during a 3-year follow-up. Mean gradient decreased by 35.8% (p < 0.0001; 95% confidence interval -39.6%, -31.7%) from postoperative values to the 3- to 6-month follow-up and by 6.1% (p = 0.004; 95% confidence interval -10.1%, -2%) at each subsequent interval; effective orifice area increased by 17.2% (p = 0.0001; 95% confidence interval 12.0%, 22.6%) initially and by 4.4% (p < 0.001; 95% confidence interval 1.8%, 7.0%) thereafter. At 2 years of follow-up, mean gradient was 3.3 +/- 2.1 mm Hg and mean effective orifice area was 2.2 +/- 0.8 cm2. Studies on left ventricular mass were carried out on 84 patients. Left ventricular mass decreased by 14.3% (37.8 +/- 57.9 gm; p < 0.0001; 95% confidence interval -53.7, -21.9 gm) and left ventricular mass index decreased by 15.2% (21.1 +/- 30.5 gm/m2; p < 0.0001; 95% confidence interval -29.5, -12.7 gm/m2) from postoperative values to the 3- to 6-month follow-up interval. The reduction in residual gradient and potential regression in left ventricular hypertrophy may have a beneficial prognostic implication. We believe that the unique stentless design of the Toronto SPV Stentless Valve allows this to occur.

Effects of valve substitute on changes in left ventricular function and hypertrophy after aortic valve replacement

BACKGROUND

Residual left ventricular hypertrophy adversely affects long-term outcome after aortic valve replacement. A stentless biological valve in the aortic position has been shown to offer a better hemodynamic profile than a stented one. However, it remains to be defined whether this difference is translated into inter-mediate-term effects on left ventricular structure and function.

METHODS

One hundred thirty-seven patients receiving single aortic valve replacement (52 with concomitant coronary artery bypass graft) were enrolled in this study. Ninety-eight were men, and the mean age was 68 years (range, 55 to 90 years). Of the 137 patients, 39 had an aortic homograft, 72 a Toronto stentless porcine valve, and 26 had a stented porcine or bileaflet mechanical valve, with mean valve size of 25 +/- 2.5 mm (mean +/- standard deviation). Left ventricular muscle mass and function were assessed by M-mode echocardiography performed before and 0.5, 6, 12, 24, and 36 months after operation, and recorded on paper for off-line digitizing. Peak valve prosthesis pressure gradients were quantified by continuous wave Doppler.

RESULTS

A total of 330 echocardiograms obtained during this study were adequate for computer digitizing. Clinical data, preoperative left ventricular function, and hypertrophy were similar between the three groups. Significant improvement in left ventricular function and major regression of left ventricular hypertrophy had occurred in the entire population by 6 months after operation. Multivariate analysis of variance showed that patients with previous aortic regurgitation had a larger left ventricular cavity size (p < 0.001) and greater mass index (p = 0.001) postoperatively than those with previous aortic stenosis. In addition, peak valvular gradient was lower (p < 0.001), mass index less (p < 0.001), and left ventricular function more normal both systolic, by a greater peak velocity of dimension shortening (p = 0.05) and wall thickening (p = 0.002), and diastolic, by a greater peak velocity of dimension lengthening (p = 0.046), with an aortic homograft or stentless porcine valve compared with a mechanical or stented biological valve. There was no significant difference in peak valve gradient, left ventricular mass index, or function between the aortic homograft and the stentless porcine valve. Age, sex, and concomitant coronary artery bypass graft, as well as aortic cross-clamp time, cardioplegia method, and valve size all proved to be insignificant determinants of postoperative left ventricular hypertrophy or function.

CONCLUSIONS

In the first 2 years after implantation, the superior hemodynamic performance of aortic homograft and stentless porcine valve appears to result in more extensive regression of ventricular hypertrophy and greater improvement of left ventricular function than occurs with a mechanical or stented biological valve. These findings encourage the use of a stentless biological valve in older patients requiring aortic valve replacement, and a larger scale long-term randomized study of stentless versus stented biological valve or mechanical valve seems warranted.