Stentless Bioprosthesis Research Articles

Thrombocytopenia after aortic valve replacement with the Freedom Solo stentless bioprosthesis

Stentless bioprostheses have been considered to achieve superior hemodynamics over stented bioprostheses for aortic valve replacement with improved long-term performance. We observed severe thrombocytopenia in patients who received the Sorin Freedom Solo aortic stentless pericardial bioprosthesis within the first days after implantation. Absolute and relative platelet counts within 2 weeks after implantation of either a stentless (Sorin Freedom Solo) or a stented (Sorin Mitroflow) bovine pericardial bioprosthesis were compared in a matched-pairs analysis in 40 patients. Except the preoperative values, absolute platelet count was higher at all time points in the Mitroflow group. In the Mitroflow group, the mean platelet count moderately dropped to a minimum of 60% of the initial value on POD 3 and fully recovered by POD 8. In the Freedom Solo group, platelet loss was significantly more severe (minimum relative value 25% on POD 4) with no recovery during follow-up (60% on POD 13). Eight patients of the Freedom Solo group experienced a critical platelet drop towards <20% of their initial values, in five of them absolute numbers decreased below 30,000/microl. No bleeding complications or other morbidity occurred. Attention should focus on the platelet count after implantation of the Freedom Solo bioprosthesis, especially in patients who are supposed to receive platelet inhibitors. However, the described phenomenon remains unexplained.

Durability of bioprosthetic cardiac valves.

The choice of type of heart valve prosthesis is determined by the patient's age since bioprostheses have a limited lifespan. This article reviews current recommendations and the literature on cardiac valve replacement. Selective literature search in Medline/PubMed back to 1996 and review of current national and international recommendations from specialist societies. The recommendations guiding the type of heart valve replacement have been revised in recent years. Of particular interest are the new generation of biological prostheses with extended durability, a growing use of stentless bioprostheses, a decrease in mortality of reoperation and an increase in life expectancy. Comorbidities such as chronic renal insufficiency or chronic atrial fibrillation are no longer contraindications to bioprosthesis. The number of heart valve replacements in recent years rose despite a concomitant increase in valve repairs. Aortic valves are being increasingly replaced by bioprostheses. The choice of heart valve prosthesis should be tailored to each patient taking into account the patient's age, life expectancy, comorbidities, and life style. Different decisions may be made now than those based on earlier recommendations resulting in an individualized treatment, in patients over the age of 65 or 70.

Functional and biomechanical evaluation of a completely recellularized stentless pulmonary bioprosthesis in sheep

In a previous study we showed that recellularization of a stentless bioprosthetic valve is stimulated 1 month after implantation in the pulmonary position, when its matrix (acellular photo-oxidized bovine pericardium) was preseeded by intraperitoneal implantation during a 3-day period. The present study reports on the functional and biomechanical properties of such valves (n = 19) in sheep up to 5 months after implantation. Similar valves (n = 20) that were not intraperitoneally preseeded served as controls. Recellularization was partial in control valves and excessive in preseeded valves: 66% versus 223% of cellularity of native valves, respectively (P < .05). The valves were endothelialized and contained interstitial cells depositing new matrix (collagens and elastin). However, phenotyping revealed an increased proportion of cells with contractile properties (30%-40% alpha smooth muscle actin+) in both groups. Intraperitoneally seeded valves had thicker and shorter leaflets that were associated with mildly increased peak gradients and regurgitation. Characterization of the matrix properties revealed a gradually degrading matrix (+/-25% loss of collagen organization at 5 months) and a concomitant alteration of its biomechanical properties, that is, decreased strength, stiffness, and maximum force. However, overall valve function remained intact, and the biomechanical properties of the whole valves were superior to that of the native valves. The ectopic in vivo seeding paradigm provides full recellularization. However, the volume fraction of the cellular phenotypes is not optimal, resulting in inadequate remodeling of the valves.

Ten-Year Experience With Stentless Aortic Valves: Full-Root Versus Subcoronary Implantation

We compared the midterm outcome after aortic valve replacement with the Freestyle stentless bioprosthesis for the full-root or subcoronary implantation technique, while adjusting for patient and disease characteristics by a propensity score. Between 1996 and 2005, 1,014 patients underwent aortic valve replacement with the stentless Medtronic Freestyle bioprosthesis, 168 using full-root technique. Based on a saturated propensity score, 148 matched pairs were created. Mean age of the 296 patients was 73 +/- 3 years. Mean follow-up time was 32 +/- 30 months (maximum, 116 months). Operative mortality was 4.7% and 2.7% (p = 0.36) in the full-root and subcoronary groups, respectively. Freedom from reoperation, prosthetic valve endocarditis, major bleeding, and thromboembolism after 9 years was 98% +/- 1% and 90% +/- 7% (p = 0.38), 95% +/- 3% and 92% +/- 7% (p = 0.76), 72% +/- 21% and 98% +/- 2% (p = 0.12), and 75% +/- 8% and 84% +/- 7% (p = 0.28), for full-root and subcoronary groups, respectively. Survival rates after 9 years were 34% +/- 24% and 33% +/- 11% (p = 0.46), for the full-root and subcoronary groups, respectively. Patients in the full-root group received larger valve sizes (p = 0.03), and the mean transprosthetic gradients at discharge were significantly lower for each valve size. Nevertheless, during follow-up, peak gradients decreased to a greater extent in patients presenting high peak gradients (>36 mm Hg) at discharge. As risk-adjusted comparison of both implantation techniques did not reveal any differences regarding operative and midterm outcomes, full-root replacement can be liberally performed in patients with small aortic roots, annuloaortic ectasia, or requiring replacement of ascending aorta.

Peeled Left Coronary Artery From Stentless Bioprosthesis

Peeled Left Coronary Artery From Stentless Bioprosthesis

Invited commentary

Patient prosthesis mismatch is undesirable and continues to be a controversial topic since the beginning of aortic valve replacement. The major issue with patient prosthesis mismatch is the effective orifice area: all valve prostheses except stentless bioprostheses had a significantly smaller effective orifice area than the normal native valve. Therefore, in many patients with prosthetic heart valves, left ventricular outflow obstruction improved from severe to moderate [1], but a pathologic transprosthetic pressure gradient remains.

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

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

Use of the pericardial cord as a substitute for an infected mitral prosthetic ring associated with aortic prosthetic valve endocarditis

We report the case of a 61-year-old man with prosthetic valve endocarditis after both aortic valve replacement and mitral annuloplasty. Necrotic tissue and dehiscence of the suture line in the aortic annulus were found, and the infection extended to the anterior portion of the mitral prosthetic ring. The autologous pericardial cord was used as a substitute for the infected mitral prosthetic ring, and aortic root replacement was performed with a stentless bioprosthesis. The autologous pericardial cord was useful as a substitute for an infected mitral prosthetic ring.

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.

Effect of surgeon on transprosthetic gradients after aortic valve replacement with Freestyle® stentless bioprosthesis and its consequences: A follow-up study in 587 patients

BackgroundThe implantation of stentless valves is technically demanding and the outcome may depend on the performance of surgeons. We studied systematically the role of surgeons and other possible determinants for mid-term survival, postoperative gradients and Quality of Life (QoL) after aortic valve replacement (AVR) with Freestyle® stentless bioprostheses.MethodsBetween 1996 and 2003, 587 patients (mean 75 years) underwent AVR with stentless Medtronic Freestyle® bioprostheses. Follow-up was 99% complete. Determinants of morbidity, mortality, survival time and QoL were evaluated by multiple, time-related, regression analysis. Risk models were built for all sections of the Nottingham Health Profile (NHP): energy, pain, emotional reaction, sleep, social isolation and physical mobilityResultsActuarial freedom from aortic valve re-operation, structural valve deterioration, non-structural valve dysfunction, prosthetic valve endocarditis and thromboembolic events at 6 years were 95.9 ± 2.1%, 100%, 98.7 ± 0.5%, 97.0 ± 1.5%, 79.6 ± 4.3%, respectively. The actuarial freedom from bleeding events at 6 years was 93.1 ± 1.9%. Estimated survival at 6 years was similar to the age-matched German population (61.4 ± 3.8 %). Predictors of survival time were: diabetes mellitus, atrial fibrillation, peripheral vascular disease, renal dysfunction, female gender > 80 years and patients < 165 cm with BMI < 24. Predictive models showed characteristic profiles and good discriminative powers (c-indexes > 0.7) for each of the 6 QoL sections. Early transvalvular gradients were identified as independent risk factors for impaired physical mobility (c-index 0.77, p < 0.002). A saturated propensity score identified besides patient related factors (e.g. preoperative gradients, ejection fraction, haematological factors) indexed geometric orifice area, subcoronary implantation technique and individual surgeons as predictors of high gradients.ConclusionIn addition to the valve size (in relation to body size), subcoronary technique (versus total root) and various patient-related factors the risk of elevated gradients after stentless valve implantation depends, considerably on the individual surgeon.Although there was no effect on survival time and most aspects of QoL, higher postoperative transvalvular gradients affect physical mobility after AVR.

Aortic Valve Endocarditis by Capnocytophaga Haemolytica

We report a case of a 51-year-old patient with suspected prosthetic valve endocarditis. Capnocytophaga haemolytica was isolated in blood cultures and the repeated echocardiograms showed growth of vegetations and disruption of the proximal prosthetic valve suture line with progressive aortic regurgitation. The patient underwent a root debridement and replacement with a stentless bioprosthesis.

Aortic valve replacement with the Sorin Pericarbon Freedom stentless prosthesis: 7 years’ experience in 130 patients

Aortic stentless pericardial valves were introduced into clinical practice to combine properties of both stentless and pericardial prostheses. The aim of this single-center retrospective study was to assess midterm clinical and hemodynamic results of aortic valve replacement with the Sorin Pericarbon Freedom stentless bioprosthesis. From July 1999 through November 2005, 130 consecutive patients (73 [56.1%] male patients) underwent aortic valve replacement with the Sorin Pericarbon Freedom bioprosthesis at our institution. Mean age was 76 +/- 5 years (range, 42-86 years), and associated procedures were performed in 50 (38.4%) patients; of these, 41 were coronary artery bypass grafts. Surgical intervention under urgent/emergency conditions and reoperations were performed in 18 (13.8%) and 7 (5.3%) patients, respectively. Mean crossclamp and cardiopulmonary bypass times were 82 +/- 24 and 125 +/- 40 minutes, respectively. All patients underwent clinical and echocardiographic follow-up (100% complete), and the total cumulative follow-up was 324 patient/years (mean, 2.5 +/- 1.8; range, 6 months-7 years). Overall hospital mortality was 8.4%. Overall patient survival was 63% +/- 6% and 50% +/- 10% at 5 and 7 years, respectively. Late deaths occurred in 23 patients, and 6 of them were valve related (1.8% patient/years). Freedom from valve-related death and reoperation was 91% +/- 4% and 94% +/- 4%, respectively, at 7 years. No structural valve deterioration was observed. Endocarditis, thromboembolism, and hemorrhagic complications occurred in 2 (0.6% patient/years), 1 (0.3% patient/years), and 1 (0.3% patient/years) patients, respectively. Mean transprosthetic gradients for valve sizes 23, 25, and 27 were 12.1 +/- 3.8, 10.8 +/- 3.8, and 9 +/- 3.1 mm Hg, respectively. The Sorin Pericarbon Freedom stentless bioprosthesis provides good early and midterm results in terms of hemodynamic performance, survival, and freedom from valve-related complications.

Early Hemodynamic Results of the Shelhigh SuperStentless Aortic Bioprostheses

Stentless valves have been demonstrated excellent hemodynamic performances favoring the recovery of left ventricular function and the ventricular hypertrophy regression. The aim of the study was to evaluate the early hemodynamic performance of the Shelhigh SuperStentless aortic valve (AV). Between July 2003 and June 2005, 35 patients (18 females; age 70.8 +/- 11.7 years, range: 22-85) underwent AV replacement with the Shelhigh SuperStentless bioprostheses. Most recurrent etiology was senile degeneration in 25 (71%) patients and 24 (69%) were in New York Heart Association (NYHA) functional class III or IV. Concomitant coronary artery bypass grafting was performed in nine patients (25.7%) and mitral valve surgery in two patients (5.7%). Doppler echocardiography was performed before surgery, at six-month and one-year follow-up. There were no hospital deaths and no valve-related perioperative complications. During one-year follow-up, no endocarditis or thromboembolic events were registered, no cases of structural dysfunction or valve thrombosis were noted. Mean and peak transvalvular gradients significantly decrease after AV replacement, with an evident reduction to approximately 50% of the preoperative values at six months. A 20% reduction was also observed for left ventricular mass (LVM) index at six months, with a further regression at one year. Correspondingly, significant increases in effective orifice area (EOA) and indexed EOA were determined after surgery (0.87 +/- 0.14 versus 1.84 +/- 0.29 cm2 and 0.54 +/- 0.19 versus 1.05 +/- 0.20 cm2/m2, respectively). Valve prosthesis-patient mismatch was moderate in five patients and severe in one case. Shelhigh SuperStentless AV provided good and encouraging hemodynamic results. Long-term follow-up is necessary to evaluate late hemodynamic performance and durability of this stentless bioprosthesis.

Meta-Analysis of Valve Hemodynamics and Left Ventricular Mass Regression for Stentless Versus Stented Aortic Valves

Stentless aortic bioprostheses have been advocated as being superior to conventional bioprosthetic valves, with benefits including superior left ventricular mass regression and larger effective orifice area. Several high-quality randomized studies now exist on this topic, and we sought to summarize them by meta-analysis. The literature was searched from 1995 to 2006, in MEDLINE, EMBASE, CRISP, metaRegister of Controlled Trials, and the Cochrane database. Experts were also contacted and reference lists searched. Studies were combined using the inverse variance fixed-effects model. Heterogeneity was assessed and a sensitivity analysis performed. Publication bias was also investigated. Ten studies were identified that included 919 patients in which the Freedom (Sorin Biomedica Cardio, Via Crescentino, Italy), Freestyle (Medtronic, Minneapolis, MN), Prima Plus (Edwards Life Sciences, Irvine, CA) and the Toronto and Biocor (St Jude Medical, St. Paul, MN) valves were used. The mean aortic valve gradient was lower in the stentless groups, with a weighted mean difference (WMD) of -3.57 mm Hg (95% confidence interval [CI], -4.36 to -2.78; p < 0.01). The left ventricular mass index was significantly lower in the stentless groups at 6 months (WMD, -6.42; 95% CI, -11.63 to -1.21; p = 0.02), but this improvement disappeared after 12 months (WMD, 1.19; 95% CI, -4.15 to 6.53; p = 0.66). The weighted mean increase in cross-clamp time was 23 minutes, and the increase in bypass time was 29 minutes with a stentless valve. This meta-analysis showed that stentless aortic valves provide an improved level of left ventricular mass regression at 6 months, reduced aortic gradients, and an improved effective orifice area index, at the expense of a 23-minute longer cross-clamp time and a 29-minute longer bypass time.

Stented versus Stentless Bioprostheses in Aortic Valve Stenosis: Effect on Left Ventricular Remodelling

Whether the use of stentless aortic bioprostheses improves hemodynamics more than stented bioprostheses in the small aortic root is still a matter of debate. Early- and mid-term effects were compared between 2 different types of stentless bioprotheses and 1 type of stented bioprosthesis for left ventricular remodelling. The effects of the bioprotheses were studied by echocardiography in 68 patients (age, 74 +/- 7 years) with aortic annulus diameter < or =23 mm who were undergoing prosthesis implantation due to aortic isolated stenosis. Stented bioprostheses (Carpentier-Edwards Perimount [CEP]) were implanted in 36 subjects and stentless bioprostheses (18 Toronto SPV and 14 Shelhigh Super Stentless) were implanted in 32 subjects. A progressive and similar decrease in left ventricular mass of 30% was observed in both stented and stentless bioprostheses at 12 months. A progressive increase in transprosthetic effective orifice area and a decrease in transprothetic pressure gradient were observed at 3, 6, and 12 months in the Toronto group, but these variables showed improvement only at 3 months in the CEP and Shelhigh groups. No mortality occurred during surgery or during the 1-year follow-up period. Our results confirmed good feasibility of aortic stented and stentless bioprostheses implantation in the elderly population. A 30% decrease in left ventricular mass occurred in the early- and mid-term (12 months) periods after surgery with all 3 types of bioprostheses. Advantages consisting of a progressive increase in transprosthetic effective orifice area and a decrease of the transprosthetic pressure gradient were observed in the Toronto group in comparison to the CEP and Shelhigh groups. These observations may help surgeons in choosing bioprostheses.

Complete aortic obstruction owing to the proximal dehiscence of a stentless root bioprosthesis

A 67-year-old man was admitted for chest pain. Eighteen months earlier, he underwent replacement of his aortic USA) owing to annuloaortic ectasia. Immediate postoperative and one-year echocardiograms and chest computed tomography (CT) examinations showed a well-functioning bioprosthesis, with no aortic root complications. The patient was asymptomatic until the recent onset of chest pain. A thallium myocardial scan showed mild ischemic changes in the inferoapical distribution. Coronary angiography demonstrated normal coronary arteries. However, contrast injection within the aortic root depicted complete obstruction of the ascending aorta during end-systole (Figure 1). A peak gradient of at least 80 mmHg was measured between the left ventricle and the ascending aorta. The CT scan was not conclusive. Figure 1) Aortogram depicting full Freestyle root (Medtronic Inc, USA) expansion during diastole (A), partial occlusion of the aortic root during early systole with only minimal opacification of the aortic root (white arrow) (B) and complete aortic occlusion of ... At reoperation, one-half of the proximal anastomosis of the Freestyle root was dehisced. During systole, the surrounding tissues, mainly the pericardium, created a ‘cul-de-sac’ around the Freestyle prosthesis, with the inward displacement of the dehisced Freestyle graft creating the aortic occlusion. With the Freestyle graft expanded in diastole, the space between the Freestyle wall and the surrounding tissue was minimal, thus explaining the absence of a pseudoaneurysm on CT. No signs of infection were present. A modified Bentall procedure, using a custom composite stented bioprosthesis graft, was performed. The postoperative course was uneventful and the patient was free of complications 12 months after the surgery.

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

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. 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). 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. 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.

Late Disruption of a Freestyle Stentless Bioprosthesis Used for Repair of Sinus of Valsalva Aneurysm of Noncoronary Cusp

We present a case of disruption of the porcine aortic wall of the 27-mm Freestyle stentless bioprosthesis 5 years after the subcoronary implantation to exclude the sinus of Valsalva aneurysm of the noncoronary cusp. At the urgent reoperation, the inflow suture line was found to be intact, and therefore a new stented valve was sutured with the inflow Dacron cuff after removal of ruptured valve. The subcoronary implantation technique creates a cavity between the prosthetic and native aortic walls filled with hematoma. The outflow suture line dehiscence caused blood flow into the cavity, porcine aortic wall rupture, and leaflet destruction.

Stentless vs. stented aortic valve bioprostheses: a prospective randomized controlled trial

We sought to assess the haemodynamic profile of the Freedom stentless aortic valve compared with a stented bioprosthesis in a randomized controlled trial using echocardiography. Sixty patients (mean age 73 years) undergoing bioprosthetic aortic valve replacement (AVR) were randomized to either Sorin Freedom stentless (n=31) or Sorin More stented (n=29) valves. The primary endpoints were left ventricular mass index (LVMI) reduction at 6 and 12-months. We also assessed post-operative effective orifice area index (EOAI), aortic gradient and operative time. There were no significant differences in baseline characteristics. The stentless valve was associated with a lower post-operative gradient [PG 17 (12) vs. 31 (13) mmHg, P<0.0001] and greater EOAI [1.1 (0.3) vs. 0.8 (0.2) cm2/m2, P<0.0001]. A highly significant reduction in LVMI occurred by 6 months in both groups, but LVMI was significantly lower in the stentless group [LVMI 119 (39) vs. 135 (30) g/m2, P=0.05]. However, there was continued regression of left ventricular hypertrophy (LVH) in the stented but not in the stentless group, resulting in no significant difference in LVMI at 12 months [119 (36) vs. 126 (31) g/m2, P=0.42]. The use of the Sorin Freedom stentless bioprosthesis for AVR results in lower PG and greater EOA when compared with a Sorin More stented valve. This is associated with earlier regression of LVH.

Extensive dehiscence of a stentless bioprosthesis with only mild paravalvular regurgitation after replacement of a degenerated bicuspid aortic valve

We report the case of a 54-year-old patient admitted for rehabilitation after implantation of a stentless bioprosthesis due to severe insufficiency of a degenerated bicuspid aortic valve. The patient could fully participate in a standard cardiac rehabilitation program without any signs of haemodynamic instability. Transthoracic echocardiography showed a small mobile subvalvular structure and only mild paravalvular reflux. Transesophageal echocardiography, however, revealed extensive dehiscence of the bioprosthesis with the need for urgent reoperation. We discuss the probable causes and encourage routine echocardiography after valve operations with generous application of transesophageal echocardiography in every suspicious case.