Stentless Aortic Valve Replacement Research Articles

Early Regional Assessment of LV Mass Regression and Function after Stentless Valve Replacement: Comparative Randomized Study

Early regional performance and hypertrophy regression after stentless aortic valve replacement are still incompletely characterized. We compared early postoperative changes of segmental thickness and function after stentless and stented aortic valve replacement as assessed by cardiac magnetic resonance (CMR). In 16 patients randomly assigned to stented (Mosaic, 8 patients) and stentless (Freestyle, 8 patients) groups, 4 parallel short-axis images at the level of the apex (slice 4), midventricle (slices 2-3), and mitral valve (slice 1) were obtained with a 1.5 T CMR scanner (Magnetom Sonata, Siemens) before and 1 month after surgery. Cine images were obtained using an echo gradient sequence. Left ventricle mass was calculated as the difference between the left ventricular end-diastolic volume at the epicardial and endocardial borders multiplied by a myocardium density factor (1.05). Each slice was divided into 8 segments (octants) from anterior (octant I-II) to septal (octant V-VIII). A total of 32 segments encompassed the entire heart. From each of these elements end diastolic thickness and systolic function (fractional thickening) were calculated. In stentless valves significant reduction of septal octant thickness on the midventricular slice was noted. There was no difference in regional systolic function-segment thickening. In stented valves no segmental thickness changes were observed. In stentless valves there was early postoperative thickness reduction of septal segments at the midventricular level. However, this finding did not coincide with changes in segmental function.

Use of stentless xenografts in the aortic position: determinants of early and late outcome

Background. Whether to perform a stentless aortic valve replacement (AVR) is not well established. Our aim was to determine the outcome after AVR with stentless xenograft valves. Methods. Between 1996 and 2001, a total of 404 patients (mean age 70.4 years) underwent a stentless AVR by one surgeon in our unit. Concomitant procedures were performed in 132 patients (33%). Twenty patients (6.4%) had undergone previous AVR. Eleven types of stentless xenograft valves were implanted: Medtronic Freestyle in 221 patients (55%), Shelhigh in 55 (14%), Shelhigh composite conduit in 33 (8%), Sorin in 26 (6%), Cryolife O‘Brien in 25 (6%), Aortech-Elan in 17 (4%), Edwards Prima in 14 (4%), Toronto SPV in 7 (2%), and other valves in 6 (1%). A subcoronary implantation technique was used in 302 cases (76%), complete root replacement in 62 (15%), and a modified Bentall-De Bono procedure in 33 (8%). Mean follow-up was 19.4 months (range, 1.2 to 60.6 months). Results. Overall hospital mortality was 4.2%. This was 2.4% for isolated AVR, 3.6% for AVR and coronary artery bypass grafting, 5.5% for replacement of two or more valves, and 12% for the modified Bentall procedure. On multiple logistic regression redo cardiac operation ( p = 0.0006), cardiogenic shock ( p = 0.001), left ventricular ejection fraction less than 0.30 ( p = 0.01), modified Bentall procedure ( p = 0.03), and endocarditis ( p = 0.04) were predictors of in-hospital death. Five-year freedom from thromboembolism, hemorrhage, prosthetic endocarditis, structural valve deterioration, and reoperation was 97%, 99%, 99%, 98%, and 96%, respectively. Kaplan-Meier survival at 5 years was 88%. On Cox regression, cardiogenic shock ( p = 0.001) and older age ( p = 0.03) were adverse predictors of survival. At echocardiographic examination within 6 months from the operation, mean aortic valve gradients were 15 ± 6 mm Hg, 12.8 ± 3 mm Hg, 10.8 ± 4 mm Hg, 9.3 ± 3 mm Hg, 9.1 ± 4 mm Hg, and 8.2 ± 3 mm Hg for valve sizes of 19, 21, 23, 25, 27, and 29 mm, respectively. Conclusions. The availability of several stentless valve designs facilitates the surgical treatment of diverse aortic valve or root diseases with encouraging early and midterm results. Patients requiring concomitant procedures may also benefit from the excellent hemodynamic characteristics of a stentless valve. We consider stentless AVR the treatment of choice for patients older than 60 years and those having small aortic roots.

Impact of implant technique following freestyle stentless aortic valve replacement

Background. Stentless aortic bioprostheses have excellent hemodynamics and clinical outcomes. The purpose of the present study was to determine whether implant technique of the Freestyle aortic root bioprosthesis impacts clinical outcomes or hemodynamic performance. Methods. The long-term multicenter study of the Freestyle stentless aortic bioprosthesis includes 500 consecutive patients implanted using the subcoronary and 162 using the full root technique. Clinical outcomes and echocardiographic hemodynamics were compared through 5 years. Results. There were no differences between groups in time to death, valve-related death, or reoperation. The incidence of operative death was higher in the full root than in the subcoronary group (odds ratio 3.97, p = 0.001). Patients in the subcoronary group were more likely to have New York Heart Association functional class III or IV symptoms at 1 year (1.7% versus 0%, p = 0.04) and 5 years postoperatively (4.4% versus 0%, p = 0.02). Mean gradient was lower ( p = 0.0004) and effective orifice area larger ( p = 0.04) in the full root group. Left ventricular mass index decreased in both groups. The preponderance of patients in both groups had no or trivial aortic regurgitation through 5 years. Conclusions. Full root implantation of the Freestyle stentless aortic bioprosthesis was associated with higher operative mortality, but somewhat better hemodynamics, functional class, and freedom from aortic regurgitation. Higher operative mortality argues against the empiric replacement of the ascending aorta in the absence of aortic root pathology. In appropriately selected patients, both implant techniques are viable alternatives for valve implantation.

Stentless aortic valve replacement in elderly patients

Objective. Seven-year clinical and hemodynamic results of the Cryolife O‘Brien (CLOB) stentless bioprosthesis in elderly patients are reported.Methods. From 1993 to 2000, 36 patients aged >75 years had a CLOB implanted in the aortic position. Eighteen (50%) were male. All patients were monitored with serial echocardiograms performed preoperatively, at discharge, six months, one year and yearly thereafter.Results. The 30-day mortality was 2.4% (1/36). Actuarial survival at one, five and seven years were 96.7±1.5, 94.8±2.0 and 94.8±2.0%, respectively. Peak and mean gradients (PG and MG) reduced and effective orifice area index (EOAI) increased over time (P<0.001). Left ventricular mass index (LVMI) reduced by 32 g/m2 at discharge (P<0.001) and by 33 g/m2 at six months (P<0.001) without further significant changes.Conclusions. In our series CLOB xenograft resulted to be a satisfactory valve substitute in elderly patients.

Time course of left ventricular remodeling after stentless aortic valve replacement

Background Stentless aortic valves are associated with a significant decrease in left ventricular hypertrophy. This study examined the time course and factors affecting left ventricular mass regression (LVMR) after aortic valve replacement (AVR) with Cryolife O’Brien (CLOB) (Cryolife International, Atlanta, Ga) stentless valves. Methods Between 1993 and 2000, 130 consecutive patients underwent AVR with CLOB. Mean age was 71.3 ± 6.3 years. Sixty-four (49.2%) were male. Mean body surface area (BSA) was 1.7 ± 0.2 m2. Mean valve size implanted was 23.6 ± 2.0 mm. All patients were monitored with serial echocardiograms; the first study was performed preoperatively, and subsequent controls were at 6 months, 1, 2, 3, 4, 5, 6, and 7 years, respectively. Left ventricular mass was calculated by the Devereux formula and indexed by BSA. Results Analysis of variance showed a significant reduction in the left ventricular mass index (LVMI) over time (P <.001). Most LVMRs occurred within the first 6 months, and after 1 year LVMI had decreased by 37.5% with further, but not statistically significant, reductions at later examinations. We found that baseline BSA >1.75 m2, male sex, arterial blood pressure ≥150 mm Hg, left ventricular ejection fraction ≤35%, New York Heart Association functional class ≥III, non–sinus rhythm, and prevalent aortic incompetence to be factors influencing LVMR. LVMR was not related to postoperative effective orifice area ≤0.85 cm/m2 and prosthetic size. Conclusions AVR with a CLOB valve is followed by a significant LVMR that occurs soon after surgery. It is influenced by several patient-related factors: most of them can be predicted preoperatively. (Am Heart J 2001;142:556-62.)

Long-term results after aortic valve replacement with the Biocor PSB stentless xenograft in the elderly

Background. This study seeks to define the long-term results after Biocor PSB stentless aortic valve replacement (AVR) in elderly patients, including the effects of No-React treatment.Methods. We reviewed the outcomes of 106 consecutive patients, aged 70 ± 6 years, having Biocor PSB (93 standard, 13 No-React) AVR between October 1992 and October 1996.Results. There were three early deaths (3%) and 15 late deaths (15%), during a mean follow-up of 5.8 ± 1.6 years. At 8 years, survival was 82% ± 4% and freedom from cardiac death was 94% ± 3%. Freedom from valve failure was 92% ± 4% at 8 years (No-React: 92% ± 8% at 4 years). Replacement of the xenograft was required in 5 patients. Freedom from reoperation was 91% ± 4% at 8 years (No-React: 92% ± 8% at 4 years). Four bleeding and two embolic events were recorded: overall valve-related event-free survival was 81% ± 7% at 8 years (No-React: 76% ± 12% at 4 years). Age of long-term survivors averaged 77 ± 5 years and their New York Heart Association status was 1.3 ± 0.6 (versus 2.9 ± 0.6 preoperatively, p = 0.01).Conclusions. Satisfactory freedom from cardiac events and from valve deterioration added to uniform improvement in functional status despite advanced age and high prevalence of comorbid conditions make AVR with the Biocor PSB xenograft a valid long-term therapy for the elderly. No-React treatment does not influence xenograft durability.

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 cm 2 for Freestyle and 1.80 ± 0.51 cm 2 ( 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.

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 cm 2 · m −2, and mean pressure drop was 5.7 ± 3.8 mm Hg. Left ventricular mass index was 128 ± 47 g · 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 · m −2), greater pulse pressure (> 84 mm Hg) (161 ± 7 versus 133 ± 7 g · m −2), New York Heart Association class II or III (versus class I) (166 ± 10 versus 128 ± 5 g · m −2), and male sex (versus female) (160 ± 7 versus 134 ± 8 g · m −2), all p < 0.01. Mean pressure drop (> 8 mm Hg), effective orifice area index (< 1.0 cm 2 · 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.

Reoperation on stentless aortic xenografts

Background. Stentless xenografts have been proposed as substitutes for the diseased aortic valve. Cases of valve failure requiring reoperation have thus far been sporadic. To establish the prevalence and outcome of reoperation on stentless aortic xenograft valves, all patients operated on between October 1992 and October 1996 were reviewed. Methods. One hundred ninety-nine patients, 94 men and 105 women aged 70 ± 7 years, had stentless aortic valve replacement for aortic stenosis (in 139), insufficiency (19), or both (38). Three prostheses were used, including the Biocor PSB (Belo Horizonte, Brazil) (106), Toronto SPV (St. Jude Medical, Inc., St. Paul, MN) (52), and O’Brien-Angell (Cryolife, Atlanta, GA) (41). While the Biocor PSB and Toronto SPV prostheses are designed to be implanted freehand with inflow and outflow suture lines, the O’Brien-Angell valve requires a single suture line. Results. There were 7 (3.5%) total and 6 (3%) valve-related reoperative procedures during a follow-up extending up to 4 years (mean 26 ± 20 months). All but one valve-related reoperation, due to endocarditis 36 months after implant, were early (less than 12 months after initial operation). Prevalence of valve-related reinterventions was 1%, 0%, and 12%, and freedom from reoperation at 3 years was 98% ± 2%, 100%, and 81% ± 8%, in patients receiving the Biocor PSB, Toronto SPV, and O’Brien-Angell valves, respectively ( p = 0.0039). Cause of reoperation was technical in 3 (O’Brien-Angell), pannus ingrowth in 1 (O’Brien-Angell), valve tear in 1 (O’Brien-Angell), and endocarditis in 1 (Biocor PSB). All patients survived replacement of the xenograft with a stented bioprosthesis (5) or homograft root (1) and were discharged after a mean hospital stay of 6 ± 3 days (range, 4 to 12 days). At follow-up 15 ± 8 months after reintervention (range, 6 to 34 months), all patients are symptom-free with no evidence of recurrent valve obstruction, regurgitation, or infection. Conclusions. Reoperation for stentless xenograft failure is a rare overall event. Implant of the O’Brien-Angell valve may be associated with a higher prevalence of early reintervention because of nonstructural failure. When needed, reoperation on a stentless xenograft is generally a simple procedure and carries a low surgical risk.

Midterm results after aortic valve replacement with freehand stentless xenografts: a comparison of three prostheses

Objective: The ideal substitute for the diseased aortic valve is yet to be found. For the assessment and comparison of the midterm results after aortic valve replacement with three different types of freehand stentless xenografts, all patients who underwent the operation between October 1992 and April 1997 were reviewed. Methods: Of 231 patients undergoing aortic valve replacement, 106 patients (group 1) were given the Biocor PSB (Biocor Industria e Pesquisa Ltda, Belo Horizonte, MG, Brazil); 76 patients (group 2) were given the Toronto SPV (St. Jude Medical, Inc., St. Paul, Minn.), and 49 patients (group 3) were given the O'Brien-Angell valve (Bravo Cardiovascular model 300, Cryolife, Inc., Marietta, Ga.). The first two xenografts require inflow and outflow suturelines; the third xenograft needs a single-sutureline implantation. Mean age (70 ± 6 years; 70 ± 7 years; 72 ± 9 years; p = 0.6), prevalence of male sex (56 patients, 53%; 37 patients, 49%; 22 patients, 45%; p = 0.7), of aortic stenosis (72 patients, 68%; 54 patients, 71%; 37 patients, 73%; p = 0.6), and need for associated procedures (51 patients, 48%; 30 patients, 40%; 21 patients, 43%; p = 0.1) were comparable among groups. Mean aortic crossclamp time was shorter in group 3 (96 ± 24 minutes; 100 ± 23 minutes; 88 ± 25 minutes; p = 0.01). Results: Early deaths were 3 of 106 (3%) in group 1, 2 of 76 (3%) in group 2, and 2 of 49 (4%) in group 3. Follow-up of survivors ranged from 1 to 54 months (mean 32 ± 13 months). Survival at 4 years was 90% ± 3% in group 1, 95% ± 3% in group 2, 85% ± 8% in group 3 ( p = 0.3). At 4 years, freedom from valve-related events was 95% ± 6%, 100%, 70% ± 8% ( p = 0.004), while freedom from valve deterioration was 99% ± 1%, 100%, 73% ± 8% ( p = 0.001), in group 1, 2, and 3, respectively ( p = 0.001). At follow-up, reintervention on the xenograft was necessary in one patient (endocarditis) in group 1, none in group 2, and six in group 3 (technical cause, group 3; valve tear, group 2; pannus, group 1). Regression analysis showed O'Brien-Angell type of xenograft to be predictive of valve-related events ( p = 0.02), valve deterioration ( p = 0.001), and reoperation ( p = 0.001) during follow-up. Conclusions: Midterm survival after stentless aortic valve replacement is good with all three xenografts. Freedom from valve-related events, valve deterioration, and reoperation are excellent with the Biocor PSB or the Toronto SPV stentless valves but less satisfactory with the O'Brien-Angell valve. (J Thorac Cardiovasc Surg 1998;115:1287-97)

Left ventricular remodelling and improvement in Freestyle stentless valve haemodynamics.

To assess how left ventricular (LV) hypertrophy, geometry and function change after stentless aortic valve replacement for aortic stenosis, and to elucidate the physiological mechanism of the improvement in stentless valve haemodynamics. 81 patients with aortic stenosis (age 75 +/- 6 years, 47 male) underwent aortic valve replacement (plus CABG in 33 patients) with a Freestyle stentless porcine valve (mean size 23 +/- 2 mm). They were prospectively investigated by Doppler echocardiography at 2 weeks, 3-6, 12, and 24 months after operation. Two hundred and forty-six echocardiograms were obtained and analysed. Aortic valve performance was assessed from its effective orifice area (EOA), the transvalvular increase in mean flow velocity (delta mV), the deceleration time of aortic flow velocity, and mean pressure drop (mPG). LV hypertrophy was assessed from LV mass index; LV geometry, from the ratio of wall thickness to the radius (T/R ratio) and LV function, from stroke volume index (LVSVI) and myocardial stroke work (SW). By 2 years after operation, LV mass index had fallen from 162 +/- 64 to 109 +/- 36, g/m2, and T/R ratio from 0.61 +/- 0.25 to 0.43 +/- 0.10. LVSVI increased from 29.4 +/- 10 to 42 +/- 17, ml/m2, and myocardial SW from 3.1 +/- 1.6 to 5.2 +/- 2.2, mJ/cm3 (all P < 0.001 by ANOVA), while LV outflow tract diameter remained unchanged. At the same time, stentless valve EOA increased from 1.59 +/- 0.75 to 2.2 +/- 0.72, cm2, and delta mV (from 82 +/- 31 to 49 +/- 24, cm/s) and mPG (from 9.7 +/- 5.0 to 5.2 +/- 3.7 mmHg) both fell significantly (all P < 0.001 by ANOVA): as the deceleration time of aortic flow velocity increased from 153.6 +/- 64.1 to 202.7 +/- 37.6 ms (P < 0.001 by ANOVA). After stentless aortic valve replacement, LV mass index and wall thickness both fall towards normal, and myocardial stroke work increases. These ventricular remodelling processes are accompanied by a more physiological flow jet at valve cusp level, which permits a greater stroke volume to be ejected with a smaller transvavular velocity increase, so that effective orifice area increases.

Stentless valve replacement in the small aortic root

Despite the variety of different artificial heart valves available, no ideal prosthesis for the small aortic root has yet been identified. The aim of this study was to evaluate the haemodynamic performance and clinical outcome after stentless aortic valve replacement. A total of 70 patients with a small aortic root underwent Toronto ( n=61) or Freestyle ( n=9) stentless aortic valve replacement. All but three patients had aortic stenosis. Mean (s.d.) age at operation was 71.2(7.9) years. The mean annular diameter was 21.4(1.2) mm. Using controlled oversizing adjusting valve size to the sinotubular junction diameter, a 23-mm prosthesis was implanted in 23 patients and a 25-mm prosthesis in 47 patients. The maximum pressure gradient was 19.1(6.8) mmHg and effective valve orifice area was 1.47(0.27) cm 2. At discharge and at follow-up, all patients were in New York Heart Association class I or II. At follow-up there was a significant reduction in pressure gradients, an increase in effective valve orifice areas, and decrease of pre-existing left ventricular hypertrophy. In conclusion, with controlled oversizing a gain in prosthesis size of 2 to 4 mm can be achieved. Implantation of oversized stentless valves leads to improved haemodynamics and to left ventricular remodelling in patients with a small aortic root. © 1997 The International Society for Cardiovascular Surgery.

Stentless Valve Replacement in the Small Aortic Root

Despite the variety of different artificial heart valves available, no ideal prosthesis for the small aortic root has yet been identified. The aim of this study was to evaluate the haemodynamic performance and clinical outcome after stentless aortic valve replacement. A total of 70 patients with a small aortic root underwent Toronto ( n = 61) or Freestyle ( n = 9) stentless aortic valve replacement. All but three patients had aortic stenosis. Mean (s.d.) age at operation was 71.2(7.9) years. The mean annular diameter was 21.4(1.2) mm. Using controlled oversizing adjusting valve size to the sinotubular junction diameter, a 23-mm prosthesis was implanted in 23 patients and a 25-mm prosthesis in 47 patients. The maximum pressure gradient was 19.1(6.8) mmHg and effective valve orifice area was 1.47(0.27) cm2. At discharge and at follow-up, all patients were in New York Heart Association class I or II. At follow-up there was a significant reduction in pressure gradients, an increase in effective valve orifice areas, and decrease of pre-existing left ventricular hypertrophy. In conclusion, with controlled oversizing a gain in prosthesis size of 2 to 4 mm can be achieved. Implantation of oversized stentless valves leads to improved haemodynamics and to left ventricular remodelling in patients with a small aortic root.

New Trends in Aortic Valve Surgery: A critical Review of Standard Prosthesis v. Stentless Replacement and Repair

Different alternatives for the surgical treatment of aortic valve disease have been recently introduced. All consecutive patients who underwent aortic valve surgery between July 1988 and March 1994 were reviewed. There were 674 patients with a mean age of 32.4 years, mean preoperative functional class of 2.82, and rheumatic etiology in 59% of the cases. The patients were divided into 3 groups: Group I. standard aortic valve replacement with biological and mechanical prosthesis ( n = 313); Group II. stentless aortic valve replacement using homograft, pulmonary autograft and reconstruction with pericardium ( n = 145); and Group HI. aortic valve repair ( n = 216). The hospital mortality was 6.07% for the standard, 0.68% for the stentless, and 3.70% for the repair. Total follow-up was 1,304.75 patient years with a mean of 21.93 months. The actuarial survival at 66 months excluding hospital mortality was 85.24 ± 4.59% in the standard replacement, 92.63 ± 4.03% in the stentless, and 91.20 ± 3.02% in the repair group. The highest incidence of reoperation corresponded to the repair group with an actuarial freedom from reoperation of 74.26 ±7.03%, v. 92.52 ±4.52% in the standard and 85.11 ± 6.71% in the stentless group. There were no thromboembolic events in the isolated aortic valve survivors in both the stentless and repair groups and 1.28% patient years in the standard. We conclude that both the stentless aortic valve replacement and the aortic repair represent a good alternative v. standard replacement, especially for those young rheumatic patients in which anticoagulation and durability of the prosthesis is still a problem.