Stentless aortic bioprostheses: compelling data from the Second International Symposium

The Sutureless Biological Bentall Procedure: A New Technique to Create a Modular Valve-Conduit Construct

The Perceval sutureless valve (Corcym, Saluggia, Italy) has been effectively adopted by surgeons for the treatment of degenerative aortic valve stenosis. Its simplified true sutureless implantation technique has proven useful for minimally invasive cases, but the use of Perceval as part of more complex root replacement has not previously been described. We present a novel technical modification to the manufactured biologic Bentall, called the sutureless biological Bentall. This technique allows for a true modular valve-conduit construction that will simplify future reintervention.

Aortic root replacement to treat type A aortic dissection: A comparison of midterm outcomes between composite valve grafts and porcine aortic roots

BACKGROUND

Porcine aortic roots (PAR) have been reported in the literature with acceptable short- and long-term outcomes for the treatment of aortic root aneurysms. However, their efficacy in type A aortic dissection (TAAD) is yet to be defined.

METHODS

Using data from a locally collated aortic dissection registry, we compared the outcomes in patients undergoing aortic root replacement for TAAD using either of two surgical options: (a) PAR or (b) composite valve grafts (CVG). A retrospective analysis was conducted for all procedures in the period from 2005 to 2018.

RESULTS

A total of 252 patients underwent procedures for TAAD in the time period. Sixty-five patients had aortic root replacements (PAR n = 30, CVG n = 35). Between-group comparisons identified a younger CVG group (50.5 vs 64.5, P < .05) although all other covariates were comparable. Operative parameters were comparable between the two groups. The use of PAR did not significantly impact operative mortality (odds ratio [OR], 0.93; 95% confidence interval [CI], 0.22-3.61; P = .992), stroke (OR, 2.91, 0.25-34.09, P = .395), reoperation (OR, 0.91; 95% CI, 0.22-3.62; P = .882) or length of stay (coeff 2.33, -8.23 to 12.90; P = .659) compared to CVG. Five-year survival was similar between both groups (PAR 59% vs CVG 69%; P = .153) and reoperation was negligible. Echocardiography revealed significantly lower aortic valve gradients in the PAR group (8.69 vs 15.45mm Hg; P < .0001), and smaller left ventricular dimensions both at 6-week and 1-year follow-up (P < .05).

CONCLUSIONS

This study highlights the comparable short- and midterm outcomes of PAR in cases of TAAD, in comparison to established therapy.

Aortic Valve Replacement with the Medtronic Freestyle Stentless Bioprosthesis

During a five-year period from 1996 to 2000, the Medtronic Freestyle stentless bioprosthesis was implanted in 310 patients of advanced age. Age at operation ranged from 60 to 90 years (mean, 76 ± 4 years). 191 patients were female and 119 male. All implants were done by the modified subcoronary method using our own modification which enabled an improved adaptation of the porcine aortic root to the human anatomy. Two sinuses were scalloped and the third left intact. Additional coronary bypass grafts were necessary in 129 (39%) patients and mitral valve procedures in 23 (7%). Mean perfusion time was 109 ± 12 minutes and crossclamp time 87 ± 8 minutes. 16 (5%) patients died perioperatively. Another 17 (5.7%) patients died during a 1 to 5.6 year follow-up (mean, 2.9 years). There was only one valve related death due to infection of the valve. In spite of the advanced age, 95% of the survivors were free from cardiac symptoms and continued to live an active and fruitful life. The biological nature of the valve and the low gradients are perhaps reasons for the good results. The long-term results are expected to be good.

Freestyle root replacement for complex destructive aortic valve endocarditis

OBJECTIVES

In destructive aortic valve endocarditis with abscess formation in the root, homografts are used more often than xenografts. Because we had reliable perioperative results with Freestyle (Medtronic Inc, Minneapolis, Minn) xenograft root replacement in these complex patients, we analyzed the long-term outcome in this high-risk indication.

METHODS

Of 126 consecutive patients with aortic valve endocarditis treated by surgery from 1997 to 2012, 32 (25.4%) received a Freestyle aortic root replacement for severe, destructive valve endocarditis and were studied retrospectively with approval of the local ethical committee. Perioperative complications, recurrence of endocarditis, and long-term morbidity and mortality were analyzed. The follow-up period was 3 months to 11.5 years.

RESULTS

Indication for surgery was native (n = 9) and prosthetic valve endocarditis (n = 23). In 18 patients, concomitant procedures were performed: coronary bypass (n = 9), additional valve surgery (n = 6), and ascending aortic surgery (n = 7). Thirty-day mortality was 19.4% (n = 6). There were no instances of technical failure requiring modification of the surgical strategy or reoperation for anastomotic bleeding. Actuarial survival at 5 and 10 years was 61.9% and 54.2%, respectively. Freedom from death, reoperation for prostheses dysfunction, and recurrence of endocarditis as the composite end point at 5 and 10 years was 56.3% and 53.1%, respectively.

CONCLUSIONS

The Freestyle root was used successfully with no technical complications in all patients with most severe destructive aortic root endocarditis. In view of this complex patient population, short- and long-term results make this conduit a reliable choice for treatment of this condition.

Reoperation for mid-term failure of a freestyle bioprosthesis using a full root technique --a surgical case--

The aortic root of a 30-year-old man was replaced with a Freestyle stentless aortic bioprosthesis for aortic regurgitation associated with annuloaortic ectasia. His clinical course was uneventful, and he was discharged without complications. Three years and six months after surgery, he presented with a high fever. Four years after surgery, transthoracic echocardiography revealed severe aortic regurgitation. We performed exploratory surgery and discovered a torn left coronary cusp of the Freestyle bioprosthesis. Organized vegetation was adherent to the left coronary cusp leaflet. The non-coronary cusp and the right coronary cusp were normal. The diagnosis was aortic regurgitation due to valve failure related to infective endocarditis. Consequently, we reconstructed the aortic root with a composite graft (26-mm Valsalva graft and a 21-mm ON-X mechanical valve).

Torn cusp in a freestyle stentless bioprosthesis 5 years after implantation: report of a case

The Freestyle stentless bioprosthesis (Freestyle valve) is widely used throughout the world because of its durability and benefits for hemodynamic function. However, we encountered a patient who required reoperation for a cuspal tear 5 years after the implantation of a Freestyle valve. The histological findings suggested that tissue degeneration with pannus formation might play a critical role in cuspal tears.

Early Clinical and Hemodynamic Outcomes After Stented and Stentless Aortic Valve Replacement: Results From a Randomized Controlled Trial

BACKGROUND

Stentless aortic bioprostheses were shown to be hemodynamically superior to earlier generations of stented bioprostheses. Modern stented valve designs have improved hemodynamics. A prospective randomized controlled trial was undertaken to compare stentless versus modern stented valves. Our aim was to determine any differences in early postoperative clinical and hemodynamic outcomes.

METHODS

Patients with severe aortic valve stenosis (n = 161) undergoing aortic valve replacement were randomized intraoperatively to receive either the C-E Perimount (Edwards Lifesciences, Irvine, CA) pericardial stented bioprosthesis (n = 81) or the Prima Plus (Edwards Lifesciences) (porcine stentless bioprosthesis (n = 80). Transthoracic echocardiograms were performed at one week and eight weeks postoperatively to assess left ventricular mass (LVM) and transvalvular gradients (TVG).

RESULTS

There were no differences between the two groups in baseline characteristics. Cardiopulmonary bypass and ischemic times were longer in the stentless group. Despite similar native aortic annular diameters, the mean size of the prosthesis used in the stentless group was 2.1 mm (SD = 2.8) larger (p < 0.001). Early (30-day) mortality (stentless 3.7% vs stented 2.5%; p = 0.68) and morbidity was similar between groups. Eight weeks postoperatively, LVM (stentless 199 +/- 70 vs stented 204 +/- 66 grams; p = 0.32) and TVG decreased in both groups (mean systolic gradient; stentless 10 +/- 3 vs stented 10 +/- 4 mm Hg; p = 0.54) but there was no significant difference between groups.

CONCLUSIONS

Despite longer ischemic times in the stentless group, early postoperative outcomes were similar. Both stented and stentless aortic valve replacement offers excellent hemodynamics and can be achieved with low perioperative mortality.

Allograft tissue for use in valve replacement

Homograft or allograft tissue has been available for use as replacement for diseased valves or reconstruction of major vessels for decades. However, with respect to replacement of diseased valvular tissue the search for the ideal valve still continues. In this review we will discuss the clinical indications, surgical techniques, and outcome of aortic homografts.

Patient‐Prosthesis Mismatch After Small‐Size Stentless Aortic Valve Replacement

OBJECTIVE

The aim of this study was to determine the occurrence of patient-prosthesis mismatch (P-PM) after aortic valve replacement (AVR) with a small-size Cryolife O'Brien (CLOB) bioprosthesis and to evaluate its clinical and hemodynamic implications.

METHODS

Sixty-two patients (mean age 70.9 +/- 5.2 years, 77.8% females), receiving a labeled 21-23 mm CLOB between 1993 and 2000, were retrospectively studied. Effective orifice area (EOA) was calculated by the continuity equation and then indexed to the patient's body surface area (BSA) to obtain the indexed EOA (EOAI). Based on previous observations a mismatch was defined as EOAI <or= 0.85 cm2/m2.

RESULTS

Twelve patients (20%) at discharge, two (3.3%) at 6 months and none at late controls had an EOAI <or= 0.85 cm2/m2. At ANOVA determinants of mismatch were female sex (p < 0.001), age (p = 0.01), and patient's annulus index (PAI, p < 0.001). Patients with mismatch had higher mean gradients (MG, p = 0.01, and p < 0.001 at discharge and 6 months, respectively) and EOAI correlated with MG at discharge (r2= 0.72, p < 0.001) and 6-month (r2= 0.40, p = 0.001) studies. At 1 year no difference in MG was detected between patients with or without mismatch (p = ns) and EOAI did not correlate with MG (r2= 0.01, p = ns). Midwall fractional shortening did not differ in patients with or without mismatch (p = ns). Patients with an EOAI >or= 0.8 cm/m2 showed an earlier concentric remodeling up to 1 year; no difference was demonstrated at later studies between groups. Survival and clinical status results were not affected by an EOAI <or= 0.85 cm2/m2.

CONCLUSIONS

After AVR with CLOB mismatch occurred early postoperatively in a small number of patients without clinical repercussions. EOAI, significantly increasing over time, was adequate to BSA in all patients at late controls.

Modified stentless porcine valve enhances accelerated cuspal calcification in the juvenile sheep model

OBJECTIVE

Stent mounting of any bioprosthesis, induces a loss of mobility and reduces the effective valve orifice. By contrast, for stentless procedures, the higher surgical technicality remains a major obstacle for many surgeons. In an attempt to facilitate the insertion of the stentless porcine aortic valve (Toronto SPV), we tried to alter the design by lowering the invasive profile at the depth of the sinuses on both coronary sites. This could theoretically facilitate the implant of the modified stentless valve with an easygoing single layer suture at the challenging subcoronary level and make it more attractive for every surgeon.

METHODS

Modifications of the standard model were done by lowering the profile at the depth of the sinuses on both coronary sites, whether by plication or excision of the protruding porcine aortic wall at the nadir of each coronary sinus. Nine juvenile sheep underwent implantation of stentless porcine aortic valves in pulmonary position: 3 standard Toronto SPV, 3 plicated Toronto SPV and 3 excised Toronto SPV. In each series, valves were explanted after 3 months. Valves were analyzed.

RESULTS

The cusps of standard Toronto SPV were perfectly functioning and pliable, without visible calcification after three months. The calcium content of the cusps was less than those in the plicated and excised Toronto SPV (2.4 +/- 0.7 microg/mg versus 10.8 +/- 5.9 and 6.7 +/- 3.4 microg/mg). In the plicated and excised valves, calcification of the cusp was more pronounced in the commissural region (3.9 +/- 1.9, 29.0 +/- 16.7, 13.8 +/- 9.5 microg/mg in the standard, plicated and excised Toronto SPV, respectively). On the other hand, the aortic wall from the plicated Toronto SPV had more calcium than that from the other groups (53.6 +/- 6.3, 41.2 +/- 7.1, 45.2 +/- 7.4 microg/mg in the plicated, standard and excised Toronto SPV, respectively).

CONCLUSIONS

The modification of stentless porcine valve enhanced accelerated cuspal calcification in the commissural region. It accentuated that the correct implantation technique for stentless procedures is extremely important in order to prevent early degeneration.

Valved stentless composite graft: clinical outcomes and hemodynamic characteristics

BACKGROUND

The valved stentless composite graft has become well established in our hospital for replacement of the ascending aorta and aortic valve in elderly patients and those with contraindication for lifelong anticoagulation. This study was conducted to evaluate the postoperative hemodynamic characteristics and clinical outcomes after implantation of this device.

METHODS

Between November 1998 and February 2001, 45 consecutive patients with a mean age of 69 years underwent implantation of a composite graft using a stentless valve prosthesis (Toronto SPV) incorporated in a collagen-coated Dacron tube (InterGard). The indication for surgery was aortic valve disease with an accompanying true aneurysm of the ascending aorta in 42 patients and a dissection of the aortic wall in 3 patients. Postoperative echocardiographic examinations were performed before discharge from the hospital and at the time of the follow-up. Mean follow-up duration was 18 months (range 3 to 30 months).

RESULTS

There was no perioperative mortality. During follow-up, there were two noncardiac, nonvalve-related deaths. Echocardiographic evaluation before discharge and at follow-up demonstrated favorable hemodynamics of the valve prosthesis with mean transvalvular gradients of 8.5 +/- 2.9 mmHg and 8.0 +/- 3.1 mmHg, respectively. No regurgitation across the valve and no contact of the cusps with the Dacron tube were seen in any case.

CONCLUSIONS

A stentless composite graft for replacement of the aortic valve and ascending aorta offers excellent hemodynamic results and is a suitable device for patients in whom anticoagulation should be avoided.

Intraoperative transesophageal echocardiographic assessment of the effect of protamine on paraprosthetic aortic insufficiency immediately after stentless tissue aortic valve replacement

Mild paravalvular aortic insufficiency (AI) is common immediately after stentless bioprosthetic aortic valve replacement. Although resolution of paraprosthetic jets with protamine has been described, the predictability of resolution has not been addressed. Intraoperative transesophageal echocardiography was performed before and after protamine administration among 2 groups. The first group (n = 20) was used to define the prevalence and severity of paravalvular AI after stentless tissue AVR, and define a threshold value for jet size associated with resolution with protamine. A second group (n = 18) was used to prospectively test the determined threshold. Paravalvular AI occurred in 13 of 20 (65%) patients. Using a threshold value of 0.3 cm or less jet width, prospective testing revealed positive and negative predictive values for AI resolution with protamine of 93% (14 of 15) and 100% (3 of 3), respectively. Protamine administration is associated with resolution of small AI jets immediately after implantation of a stentless aortic bioprosthesis, with a jet width 0.3 cm or less strongly predictive of resolution.

Stentless xenografts and homografts for right ventricular outflow tract reconstruction during the Ross operation

BACKGROUND

Shortage of homografts prompted us to replace the transplanted pulmonary trunk with stentless xenografts during the Ross procedure. The 5-year follow-up in comparison with pulmonary homografts is presented.

METHODS

From April 1997 to March 2002, of 51 patients undergoing a modified Ross procedure 15 patients (age range 55 to 65 years, mean 59 +/- 5) received a stentless xenograft, and 36 patients (15 to 56 years, mean 36 +/- 11) a pulmonary homograft for right ventricular outflow tract (RVOT) reconstruction. Follow-up was complete for a mean of 3.1 years (range 6 to 60). Regularly performed echocardiography included determination of valve annulus, peak instantaneous gradient, leaflet performance, location of obstruction, and degree of regurgitation.

RESULTS

There was 1 late death and 1 reoperation for homograft stenosis. The homograft annulus diameter decreased by a mean of 10% (range 3 to 10 mm; p < 0.01), and peak Doppler gradient increased significantly (p < 0.001). All patients except 1 had gradients less than 25 mm Hg. Gradients in xenograft patients were stable at a low level (6.5 +/- 4.3 mm Hg to 8.8 +/- 7.4 mm Hg at the latest follow-up). Mild pulmonary regurgitation was noted in 46.6% (xenografts) and 19.5% (homografts). Leaflet quality and mobility were maintained in all patients.

CONCLUSIONS

Pulmonary homografts underlie a process of annular reduction after the Ross procedure, which is usually not associated with graft stenosis. Mild pulmonary regurgitation is more common in xenografts than in homografts. RVOT reconstruction using stentless xenografts represents a satisfactory treatment modality for aged patients.

Hydrodynamic function of the second-generation mitroflow pericardial bioprosthesis

BACKGROUND

The hydrodynamic function of the smaller size Mitroflow Synergy stented pericardial bioprostheses has been studied in an in vitro fresh tissue aortic root model and compared with previous studies of free-sewn bioprostheses.

METHODS

Three valves of each of the sizes 19, 21, and 23 mm were sutured into fresh tissue aortic roots and tested in a pulsatile flow simulator using two different ventricular input impedance conditions. A high-speed camera was used to study the leaflet opening and closing configurations. Mean pressure difference as a function of root mean square forward flow, effective orifice area, regurgitant volumes, and total energy loss across the valves was measured.

RESULTS

Mean pressure difference with respect to root mean square forward flow decreased as the valve size increased. Thus effective orifice area increased as the valve size increased. The open leaflet configuration images showed that all three sizes of Mitroflow valves had a large circular orifice with minimal open leaflet deformation. All valves closed competently with no visible leakage and no closed regurgitant volume. The Mitroflow valves showed better effective orifice areas compared with previously tested frame-mounted porcine bioprostheses but lower effective orifice areas compared with porcine stentless bioprostheses; however, the open leaflet bending deformation was better than for any of the previously tested bioprosthetic valves.

CONCLUSIONS

The hydrodynamic function of the Mitroflow Synergy stented pericardial bioprosthesis shows potential for good in vivo hemodynamic performance. The good hemodynamic performance combined with relative ease of implantation technique makes the pericardial valve a good valve in the aortic position, particularly in older patients with small annuli.

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.

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.

Stentless bioprostheses in aortic root disease

INTRODUCTION

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

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.

Early and midterm results of model 300 CryoLife O'Brien stentless porcine aortic bioprosthesis

BACKGROUND

The Cryolife O'Brien (CLOB) is a composite stentless bioprosthesis constructed from noncoronary leaflets of three porcine aortic valves. This study aimed to investigate early and midterm results after aortic valve replacement with CLOB xenograft.

METHODS

Between 1993 and 2000, the CLOB was implanted in 125 patients (62 men; mean age 71.3+/-6.4 years). Mean prosthesis size was 23.6+/-2 mm. Mean follow-up time was 37.0+/-12.1 months. Patients underwent echocardiographic studies preoperatively, at discharge, at 6 and 12 months postoperatively, and yearly thereafter.

RESULTS

Early (30-day) mortality rate was 2.4% (3 of 125 patients). Of the four late deaths, none was valve related. Actuarial 7-year survival was 93.6%+/-3%. Seven-year freedom from primary valve failure was 98.1%+/-1.8%. All patients showed an improvement of functional status (p < 0.001). ANOVA revealed a significant reduction over time in peak and mean systolic gradients (p < 0.001). Effective orifice area index increased (p < 0.001) and left ventricular mass index significantly reduced in all valve sizes (p < 0.001) during this time interval.

CONCLUSIONS

Because the early and midterm results with CLOB xenograft have been satisfactory, we encourage its use as a valve substitute, particularly in patients with small aortic roots.

Pericardial and porcine stentless aortic valves: are they hemodynamically different?

BACKGROUND

We sought to compare the early hemodynamic performance of pericardial stentless aortic valves with that of well-established porcine stentless aortic prostheses.

METHODS

A total of 169 patients (97 men and 72 women, aged 73+/-6 years) undergoing aortic valve replacement received either a pericardial (Pericarbon, Sorin Biomedica, Saluggia, Italy; n = 89) or a porcine (Freestyle, Medtronic, n = 80) stentless aortic valve. Aortic valve hemodynamics and root dynamism were assessed by Doppler echocardiography at discharge and 12 months after implantation.

RESULTS

Clinical demographic data, valve size (24.0+/-1.9 vs 24.6+/-2.3 mm), and body surface area (1.85+/-0.19 vs 1.80+/-0.19 m2) did not differ between porcine and pericardial valves (both p > 0.05). The 1-year postoperative mean valve pressure gradient (4.2+/-2.6 vs 3.7+/-2.6 mm Hg), effective orifice area (2.2+/-0.8 vs 2.2+/-0.8 cm2), and left ventricular ejection fraction (62+/-13 vs 63+/-13, %) also did not differ (all p > 0.05). However, at discharge, systolic increase in aortic sinus diameter was significantly greater in pericardial valves than in porcine ones (7.7+/-5.7 vs 4.9%+/-4.2%, p < 0.01). Furthermore, pericardial valves had a greater slope of effective orifice area-systolic aortic flow relationship (0.89+/-0.07 vs 0.70+/-0.06, cm2/100 mL/s, p < 0.01).

CONCLUSIONS

Nonprosthetic thin-walled pericardial valves appear to offer better aortic root dynamism and more efficient hemodynamics than those of porcine valves immediately after implant. At 1-year follow-up, however, both types of stentless valves provide equally excellent hemodynamics. The clinical choice between the two will depend on their long-term durability.

Aortic root remodeling with the "cuff" technique for stentless valve implantation

Aortic root and sinotubular junction dilatation and aneurysm of ascending aorta are considered relative contra-indications to implantation of a stentless valve prosthesis, because the modified aortic geometry leads to aortic incompetence and early failure of the prosthesis. Aortic root reconstruction can be performed according to various techniques. We present a surgical technique in which a tubular graft, replacing an ascending aortic aneurysm, allows sinotubular remodeling and satisfactory implantation of a stentless prosthesis. The native aorta is inserted into the vascular prosthesis at the level of the sinotubular junction which is wrapped in order to prevent commissure spreading. Sizing of the vascular and valve prosthesis is made according to annular diameter. Since October 1999, 6 patients have been operated using this technique with good results.

Echocardiographic assessment of stentless aortic bioprosthetic valves

Stentless tissue aortic valves are gaining in popularity because of advantages in hemodynamics and durability compared with stented bioprostheses. The absence of a rigid sewing ring and struts makes these valves pliable, and distortion at implantation can result in valve dysfunction. Because the anatomy and implantation techniques of stentless tissue valves are unlike those of mechanical and stented tissue valves, their echocardiographic appearance is unique on both intraoperative and subsequent transthoracic and transesophageal echocardiography. This report describes the echocardiographic appearance of normally functioning stentless tissue heterograft aortic valves as an aid to their intraoperative and subsequent echocardiographic assessment.

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.

Survival advantage of stentless aortic bioprostheses

BACKGROUND

Bioprostheses (BPs) are used to avoid anticoagulation after aortic valve replacement (AVR) in patients over 65 years of age. Stentless BPs offer established hemodynamic benefits. We sought to determine whether these advantages translate into improved survival.

METHODS

Between 1993 and 1997, follow-up data (for Food and Drug Administration submission) were collected prospectively for 160 consecutive, unselected hospital survivors who received the Freestyle valve (FS). Equivalent data were collected for 247 Carpentier-Edwards (CE) porcine xenograft patients. Detailed comparative statistical analysis was used to compare events and survival between the groups. Follow-up was 100% complete for the FS (5.2 years maximum; mean 3.2+/-1.0 years) group and 98% (7.2 years maximum; mean 3.8+/-2.0 years) for CE.

RESULTS

The groups were well matched in age (FS, 73+/-6 years; CE, 74+/-6 years), gender (FS, 58% male; CE, 62% male), ventricular function, and number of patients requiring coronary grafts (FS, 41%; CE, 37%). Actuarial survival at 5 years was 84% for FS versus 69% for CE (p = 0.023 Kaplan Meier, p = 0.009 Cox). Annual mortality rates were 3.6% for FS versus 7.1% for CE (p = 0.001). Thromboembolic rate was 0.8% per year for FS and 2.4% for CE (p = 0.024) without a difference in cardiac rhythm. Incidence of nonstructural dysfunction (paravalvular leak) was 0.2% for FS versus 1.3% for CE (p = 0.020).

CONCLUSIONS

By 5 years, the stentless valve patients had improved survival and reduced adverse events. Though differences in durability are yet to be proved, our findings support the use of stentless bioprostheses in this age group.

Replacement of the aortic valve and ascending aorta with a valved stentless composite graft: technical considerations and early clinical results

BACKGROUND

Replacement of the aortic valve and the ascending aorta with a conduit consisting of a mechanical valve and a Dacron tube has become a fairly common procedure. Commercially available conduits employing xenografts are rarely used for the same purpose, because if a reoperation becomes necessary due to degeneration of the valve prosthesis, usually the entire conduit must be replaced. A composite graft with a stentless valve, such as we describe in this article, avoids this problem, because in case of reoperation only the valve cusps need to be resected and the tube graft may be left in place.

METHODS

Surgical technique of replacement of the aortic valve and the ascending aorta with a stentless composite graft and early results of the procedure are presented.

RESULTS

Hemodynamics of the graft soon after surgery were excellent, with an average systolic gradient of 8 mm Hg and no regurgitation across the valve. There were two reoperations for bleeding in the early postoperative period.

CONCLUSIONS

The stentless composite graft we describe provides excellent hemodynamics, has no need for anticoagulation, and is expected to offer a benefit in case of reoperation.

Influence of sizing and subcoronary implantation technique on the function of porcine aortic homografts

The function and longevity of the homograft aortic valve may be influenced by valve size and subcoronary implantation technique. Dynamic function and leaflet configuration of the porcine aortic valve were analysed first in its natural root in a left heart simulator using glycerol at 120/80 mm Hg pressure and 4 l min-1 Cardiac Output (C.O.). Then the valve was implanted in the porcine root and studied: Group I (n = 4) 1-2 mm smaller, Group II (n = 8) 3-4 mm smaller and Group III (n = 4) 5-7 mm smaller donor valve than the recipient. A silicone rubber mould of the implanted valve was made and analysed. In the donor aortic root the commissural expansion for 0 to 80 mm Hg pressure was 42% which was reduced significantly in all assemblies. Group I showed the largest decrease in the orifice area (OA). In Group III decrease in the OA was less, however, two of the four valves had aortic insufficiency (AI). In Group II decrease in the OA was only 13% and there was no AI. During opening the leaflet surface was smooth and free of wrinkles in the intact valve, but had creases and folds in all three groups. All implanted valves had an indentation along the suture line disrupting the leaflet-sinus continuity. Hence, to enhance valve longevity, donor valve 3-4 mm smaller than the recipient should be chosen and the implantation technique modified to preserve the leaflet-sinus continuity.

Stentless aortic valve replacement with Freestyle or Toronto SPV: an early comparison

BACKGROUND

Stentless aortic xenograft valves have been developed to overcome the disadvantages of conventional stented prostheses. We have implanted two new aortic bioprostheses: the Medtronic Freestyle and the St. Jude Toronto SPV. Early results are compared.

METHODS

Forty-four Freestyle valves were implanted using a freestanding total root technique. Fourteen subcoronary Toronto SPV bioprostheses were implanted. Sixty-four percent of both groups (28 of 44 Freestyle and 9 of 14 Toronto SPV) underwent concurrent procedures.

RESULTS

Ischemic time was 117 +/- 21 minutes for Freestyle and 124 +/- 19 minutes for Toronto SPV. There were no operative deaths or valve-related reoperations. Aortic valve area was 1.83 +/- 0.51 cm2 for Freestyle and 1.80 +/- 0.51 cm2 (p = 0.89) for Toronto SPV. Transvalvular gradient was 8.03 +/- 4.09 mm Hg for Freestyle and 12.4 +/- 1.82 mm Hg (p = 0.002) for the Toronto SPV. Aortic regurgitation was not experienced in any Freestyle patients, while Toronto SPV patients were graded as none to trace 79% (11 of 14), mild 14% (2 of 14), and moderate 7% (1 of 14).

CONCLUSIONS

Aortic valve replacement with the Freestyle and Toronto SPV required equal time for implantation and had equal effective orifice areas. Freestyle had lower transvalvular gradient and less aortic insufficiency without increasing morbidity or mortality.

Early experience with the mosaic bioprosthesis: a new generation porcine valve

BACKGROUND

The Mosaic bioprosthesis is a new generation stented porcine valve.

METHODS

Between May 1995 and April 1998, this valve was implanted in the aortic position in 98 patients (70 men; mean age, 69.2 years [34.2 to 83.6 years]). Preoperatively 35 patients were in New York Heart Association functional class 3 or 4. Fifty-nine patients underwent concomitant procedures. The mean duration at follow-up in January 1999 was 23.7 +/- 10.2 months (0.3 to 39.4 months) and totaled 193 patient-years. All but one survivor was in New York Heart Association class 1 or 2.

RESULTS

Early complications included 1 death, 3 reoperations for bleeding, greater than mild regurgitation (paravalvar) in 1 patient and thromboembolism in 4 patients. Late complications included four deaths, study-valve endocarditis in 3 patients, more than mild regurgitation or hemolysis in 2, and thromboembolism in 2 patients. Late follow-up echocardiography in all survivors showed a mean transaortic gradient of 13.6 +/- 6.7 mm Hg, and an aortic valve area of 1.80 +/- 0.61 cm2. Valve replacement was followed by a significant and sustained decrease in left ventricular mass for all valve sizes. There has been no primary structural valve failure.

CONCLUSIONS

The early experience with the Mosaic valve in the aortic position has been promising.

Aortic Stenosis

Choice of the best surgical option for aortic stenosis (AS) must be individualized and requires discussion among patient, cardiologist, and surgeon to weigh the risks and benefits of different options. Mechanical valves have been preferred for young patients, for those with a life expectancy of more than 10 to 15 years, or for those who require anticoagulation. Bioprosthetic valves have been preferred for elderly patients, for patients with limited life expectancy, or for patients who are unable to be anticoagulated. Newer tissue valves (eg, the stentless porcine aortic bioprosthesis and homografts) as well as newer techniques (eg, the Ross procedure) have increased the number of available options and the complexity of the decision-making process.

Comparative rest and exercise hemodynamics of 23-mm stentless versus 23-mm stented aortic bioprostheses

BACKGROUND

The hemodynamic superiority of stentless valves at rest has been generally accepted, but there is a lack of studies on exercise hemodynamics.

METHODS

We assessed aortic valve hemodynamics at rest and during exercise in 10 patients with a 23-mm stentless aortic bioprosthesis (Medtronic Freestyle; Medtronic Europe SA/NV, St. Stevens Woluwe, Belgium), in 10 patients with a 23-mm stented aortic bioprosthesis (Carpentier-Edwards, SAV, model 2650; Baxter Edwards AG, Horw, Switzerland), and in 10 healthy volunteers (control group) by means of Doppler echocardiography.

RESULTS

Gradients at rest and gradients on comparable maximum exercise levels were significantly lower in patients with stentless valves compared to those with stented valves (rest: 6 +/- 2/11 +/- 4 mm Hg [mean/peak] versus 12 +/- 3/21 +/- 10 mm Hg; exercise: 9 +/- 3/18 +/- 6 mm Hg [mean/peak] versus 22 +/- 8/40 +/- 11 mm Hg). Patients with stentless valves revealed, in comparison to healthy young men, significantly higher gradients, but the small gradient difference of 3/7 mm Hg (mean/peak) at rest remained nearly unchanged throughout the exercise protocol (4/8 mm Hg [mean/peak] at 25 W, 4/9 mm Hg at 50 W and 4/9 mm Hg at 75 W). In contrast, the gradient difference between patients with stented and stentless valves increased significantly from one exercise level to the next (6/12 mm Hg [mean/peak] at rest, 8/14 mm Hg at 25 W, 12/17 mm Hg at 50 W, and 15/25 mm Hg at 75 W).

CONCLUSIONS

A stentless aortic bioprosthesis seems to be an appropriate aortic valve substitute, especially in patients who perform regular physical exercise.

Transient dysfunction of the freestyle stentless xenograft

After replacement of a bicuspid aortic valve with a Freestyle stentless xenograft, right coronary leaflet dysfunction and an elevated pressure gradient developed. Attempts to match the right and left ostia of the prosthesis, which were located at an angle of less than 120 degrees, to the native right and left ostia, which were located at 180 degrees, may have resulted in the leaflet distension. This is a suggestive finding about its implantation technique.

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.

Echocardiographic parameters of the freestyle stentless bioprosthesis in aortic position: the European experience

The objective of this study was to determine normal Doppler and 2-dimensional characteristics of the Freestyle stentless aortic bioprosthesis. The Freestyle aortic bioprosthesis is a new type of aortic xenograft, and experience is limited. We therefore determined the normal range of echocardiographic and Doppler examinations of this valve. Three hundred thirty-nine consecutive patients with a Freestyle aortic bioprosthesis underwent an echocardiographic and Doppler examination according to a common protocol. Investigations were done within 4 weeks after operation, after 3 to 6 months, and after 1, 2, and 3 years. With a valve size from 19 to 27 mm, mean gradients decreased from 7.9 +/- 5.1 mm Hg at discharge to 5.5 +/- 3. 8 mm Hg after 3 to 6 months (P <.001). Thereafter, gradients remained stable. Effective orifice area 1 year after implantation was 1.59 +/- 0.58 cm(2) for the 21-mm valves, 1.92 +/- 0.74 cm(2) for the 23-mm valves, 2.03 +/- 0.64 cm(2) for the 25-mm valves, and 2.52 +/- 0.72 cm(2) for the 27-mm valves (P <.001). The performance index, the ratio of the measured effective orifice area in the patient divided by the effective orifice area measured in vitro, increased from 67% +/- 20% at discharge to 82% +/- 29% after 1, 2, and 3 years. Performance index was especially very high in the smaller-sized valves. After implantation with the subcoronary technique or root-inclusion technique, small cavities could be seen between the native aortic root and the Freestyle valve. Doppler values were evaluated for the Freestyle stentless porcine bioprostheses in the aortic root. Gradients appear to be close to those measured in native valves over a time period of 3 years.

Manual debridement of the aortic valve in elderly patients with degenerative aortic stenosis

OBJECTIVE

We prospectively analyzed the short- and long-term results of manual debridement of the aortic valve in elderly patients with severe degenerative aortic stenosis.

METHODS

Between September 1988 and January 1997, 103 patients aged 73.7 +/- 6 years with degenerative aortic stenosis underwent the manual debridement technique. All had symptoms (angina or dyspnea, or both). Peak systolic gradient was 89 +/- 28 mm Hg. Forty-one patients (39.8%) had associated coronary artery disease necessitating revascularization.

RESULTS

Follow-up time was 42 +/- 21 months (range 3-98 months). The Kaplan-Meier estimated survival at 98 months was 50% (95% CI: 30%-70%). In-hospital mortality was 5.8% (6 patients), and late mortality was 21% (21 patients). No predictors of in-hospital mortality or of late mortality were detected. Nonfatal postoperative complications appeared in 25 patients (24%). At 8 years, freedom from endocarditis was 98% (95% CI: 95%-100%) and freedom from thromboembolic events was 99% (95% CI: 96%-100%). No patient required long-term anticoagulation as a result of the procedure. Fourteen patients (14%) required reoperation for aortic insufficiency (n = 5), restenosis (n = 8), and mitral regurgitation (n = 1). The probability of reoperation at 98 months was 23% (95% CI: 12%-35%).

CONCLUSION

Manual aortic valve debridement has low rates of in-hospital mortality, perioperative complications, and thromboembolic and infectious events and it offers freedom from anticoagulation. However, the incidence of restenosis and reoperation is high in the long term. It may therefore be regarded as an alternative in aged patients with favorable valve anatomy (no distortion and calcium deposits only on the aortic surface of the cusps), especially in those with a small aortic anulus, associated coronary artery disease, and/or contraindication for anticoagulation.

Aortic root replacement with the freestyle stentless porcine aortic root bioprosthesis

BACKGROUND

Stentless porcine prosthetic valves offer several advantages over traditional valves. Among these are superior hemodynamics, laminar flow patterns, lack of need for anticoagulation and perhaps improved durability.

METHODS

One hundred and twelve patients were operated on from September 17, 1992 to April 13, 1998 as part of a multi-center worldwide investigation. All patients received a total aortic root replacement. Patients were evaluated postoperatively at discharge, 3 to 6 months, and yearly by clinical exam and color flow Doppler echocardiography.

RESULTS

There were 4 deaths either in the hospital or within 30 days after surgery for an operative mortality of 3.6%. No patients experienced structural valve deterioration, non-structural valve deterioration, paravalvular leak, unacceptable hemodynamic performance, or postoperative endocarditis. The linearized rates for survival and thromboembolic complications at 5 years were 82.8% and 90.5% respectively. Excellent hemodynamic function is demonstrated by very low gradients, large EOA, and an exceedingly low incidence of any aortic regurgitation.

CONCLUSIONS

The Medtronic Freestyle aortic root bioprosthesis can be used safely to replace the aortic root for aortic valve and aortic root pathology. Root replacement allows optimal hemodynamic performance with no significant aortic regurgitation. Early and intermediate results are encouraging, but further follow-up is needed to determine valve durability.

Replacement of the ascending aorta and aortic valve with a valved stentless composite graft

A technique of total aortic root replacement with a stentless porcine composite graft is described. This graft is assembled during surgery using a woven polyester vascular prosthesis and a stentless aortic bioprosthesis.

Calcification characteristics of porcine stentless valves in juvenile sheep

OBJECTIVE

To compare calcification characteristics of two porcine stentless valves (Toronto SPV and Freestyle) with different designs, fixation and antimineralization techniques using a juvenile sheep model of valve implantation inside the circulation.

METHODS

The stentless valves (n = 2 x 6) were implanted in juvenile sheep in the pulmonary artery as an interposition, while the circulation was maintained with a right ventricular assist device. The model was validated by the implantation of, clinically well-known, porcine (Hancock II) and pericardial (Pericarbon) valves. Half of the valves were explanted after 3 months, the rest after 6 months. Valves were examined macroscopically, by X-ray, light microscopy (HE, Masson, Von Giesson, Von Kossa, PTAH stains), and transmission electron microscopy. Quantitative determination of the calcium content of the cusps was performed with atomic absorption spectrometry.

RESULTS

After 3 months, the Freestyle had an extensively calcified aortic wall, most prominent at the outflow side of the porcine valve. After 6 months, calcification increased transmurally, but the valve cusps were free of calcification, and the inflow side was only slightly calcified. The Toronto SPV valve also started to calcify at the inflow side of the valve after 3 months with increased calcification after 6 months. The base of the Toronto SPV valve cusps showed slight calcification after 6 months of implantation.

CONCLUSIONS

The pattern of calcification of the porcine aortic wall differs between the two studied stentless valves, with calcification located predominantly at the outflow side in the Freestyle valve, but also at the inflow side in the Toronto SPV valve. The cusps of the Freestyle valve were less prone to calcification than those from the Toronto SPV valve.

Valvular disease in the elderly

As the incidence of valvular disease in the elderly is increasing, understanding of its pathogenesis and natural progression as well as surgical approaches and device technologies are improving. Future studies are needed to develop medical interventions that slow or halt the degenerative valvular processes associated with aging. In addition, mechanical approaches with lower operative risks should be explored and the search should continue for a valve substitute that is durable, hemodynamically efficient, easy to implant, and does not require anticoagulation. Hopefully, future intervention trials will include quality of life assessments such as symptoms, functional capacity and perceptions of well being. At present, the degenerative valvular processes must be followed closely by the clinician, and individual management decisions for the elderly based on the type and severity of valve disease, comorbid medical conditions, and the risks and benefits of intervention, along with patient preferences, rather than on the chronologic age of the patient. It is becoming clear that both survival and quality of life outcomes can improve by consideration of surgery at the onset of indications, before further deterioration eliminates the opportunity to provide benefit for the elderly patient with valvular disease.

Medium-term determinants of left ventricular mass index after stentless aortic valve replacement

BACKGROUND

This study aimed to investigate the risk factors for elevated left ventricular mass index 3 to 5 years after stentless aortic valve replacement, and to elucidate the underlying physiologic mechanisms.

METHODS

Eighty-nine patients (age, 76 +/- 6 years, 51 males) having a stentless porcine valve for aortic stenosis (n = 76) or regurgitation (n = 13) were prospectively studied by Doppler echocardiography 3 to 5 years after operation. Left ventricular systolic function, mass index, blood pressure, cardiac rhythm, and New York Heart Association function class were all determined. Stentless valve effective orifice area, mean pressure drop, and the presence and degree of aortic regurgitation were quantified.

RESULTS

The mean stentless aortic valve size was 24 +/- 2 mm. At follow-up time of 45 +/- 9 months, effective orifice area index was 1.2 +/- 0.35 cm2 x m(-2), and mean pressure drop was 5.7 +/- 3.8 mm Hg. Left ventricular mass index was 128 +/- 47 g x m(-2), and ejection fraction was 63% +/- 14%. Multivariant analysis showed a greater left ventricular mass index to be associated with nonsinus rhythm (versus sinus) (163 +/- 8 versus 131 +/- 7 g x m(-2)), greater pulse pressure (> 84 mm Hg) (161 +/- 7 versus 133 +/- 7 g x m(-2)), New York Heart Association class II or III (versus class I) (166 +/- 10 versus 128 +/- 5 g x m(-2)), and male sex (versus female) (160 +/- 7 versus 134 +/- 8 g x m(-2)), all p < 0.01. Mean pressure drop (> 8 mm Hg), effective orifice area index (< 1.0 cm2 x m(-2)), the presence of mild regurgitation of the stentless valve, or the type of previous valve disease were insignificant determinants of left ventricular mass index.

CONCLUSIONS

Three to five years after the implantation, stentless aortic valve hemodynamics remain excellent. Left ventricular hypertrophy caused by previous native aortic valve disease had largely regressed. However, patient-related factors, particularly systemic blood pressure, cardiac rhythm, and function, are significant causes of late residual left ventricular hypertrophy. Thus, continued medical care and earlier surgical intervention may further improve the outlook for these patients.

The stentless porcine valve

Recognition of the long-term results of homografts has brought about a renewed interest in stentless valves. This has been matched by the introduction of several glutaraldehyde preserved porcine stentless prostheses. The early experience indicates that these valves are technically somewhat simpler to insert than homografts and are associated with satisfactory early and immediate-term results. In particular, they appear to offer an earlier and more complete resolution of left ventricular hypertrophy. Correct insertion of a stentless porcine valve needs meticulous attention to detail and awareness of the precise anatomical features of the aortic root, which is a complex structure. Although the myocardial ischemic and cardiopulmonary bypass times are longer for the more complex insertion of this prosthesis, our studies indicate that this has no serious disadvantage to the patient and is more than matched by an improved hemodynamic performance associated with more stable left ventricular function. The theoretical advantages of a stentless valve substitute in the aortic position seem clear. Further detailed prospective studies are needed to report on the long-term performance of this valve.

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 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.