Short-term hemodynamic advantages of stentless CryoLife-O'Brien valve over stented bioprostheses for aortic valve replacement

For the CryoLife-O'Brien valve (CryoLife Inc, Kennesaw, GA, USA), implanted with a single suture line, we aimed to analyze the surgical requests and the hemodynamic results compared to stented bioprostheses. Two groups of patients requiring isolated aortic valve replacement from this population were compared retrospectively: 84 patients receiving the stentless CryoLife-O'Brien valve (Group A) and 94 patients receiving stented bioprostheses (Group B). Preoperative characteristics of patients were statistically equivalent for both groups. Statistically significant differences were observed only for operative durations and post-operative transprosthetic gradients: Aorta cross-clamp and cardio-pulmonary bypass durations were statistically longer for Group A than for Group B (45.9+/-5.7 min vs. 41.1+/-6.8 min; P<0.0001; and 64.3+/-11.6 min vs. 59.3+/-11.9 min, respectively; P=0.0053); maximal gradients and mean gradients were 19.9+/-10.9 mmHg vs. 25.6+/-10.4 mmHg (P=0.0008) and 10.8+/-5.3 mmHg vs. 14.8+/-6.4 mmHg (P<0.0001). Few surgical constraints and early post-operative hemodynamic efficiency of the stentless CryoLife-O'Brien valve means that this bioprosthesis can be intented in current practice for the aortic valve replacement in elderly patients.     

Aortic valve replacement with stentless porcine aortic bioprosthesis

Twenty-nine patients were entered in a clinical trial on aortic valve replacement with a stentless glutaraldehyde-fixed porcine aortic valve. This bioprosthesis is secured to the aortic root by the same technique used for aortic valve replacement with aortic valve homografts. The functional results obtained from this operation have been most satisfactory. To assess the hemodynamic benefit of eliminating the stent of a porcine aortic valve, we matched 22 patients with a stentless porcine bioprosthesis for age, sex, body surface area, valve lesion, and bioprosthesis size to 22 patients who had aortic valve replacement with a Hancock II bioprosthesis. Mean and peak systolic gradients across the aortic bioprosthesis and effective aortic valve areas were obtained by Doppler studies. Gradients across the stentless bioprosthesis were significantly lower than gradients across the Hancock II valve for every bioprosthesis size. Effective aortic valve areas of the stentless bioprosthesis were significantly larger than the valve areas of the Hancock II valve. Our data demonstrate that the hemodynamic characteristics of a glutaraldehyde-fixed porcine aortic bioprosthesis are greatly improved when the aortic root is used as a stent for the valve. This technique of implantation is expected to enhance the durability of the bioprosthesis, because the aortic root may dampen the mechanical stress to which the leaflets are subjected during the cardiac cycle.     

Early experience with robotic aortic valve replacement.

We report our initial experience with aortic valve replacement using robotic assistance. All procedures were performed with peripheral cardiopulmonary bypass, transthoracic aortic cross-clamp, and antegrade cold crystalloid cardioplegia. One or two ports and a 5-cm intercostal incision in the right chest were used for access. All patients had aortic valve replacement performed robotically. Between February and September 2004, five patients underwent robotic aortic valve replacement. The mean age was 59 years (range 35-82 years). There were no incisional conversions, death, stokes, or reoperations for bleeding. Overall mean study times were as follows: procedure, 231.2 min (range 180-315 min); cardiopulmonary bypass, 121.5 min (range 83-173 min), and cross-clamp, 98.2 min (range 67-140 min). One patient developed postoperative pneumonia. Aortic valve replacement can be successfully performed with the da Vinci robotic system.     

Clinical use of stentless aortic valves with standard and minimally invasive surgical techniques

The stentless porcine aortic valve prostheses have the potential to provide superior hemodynamic function and durability. Our institution was a trial site for the investigational device exemption (IDE) for 2 of the 3 stentless valve bioprostheses and has clinical experience in all 3 valves that are soon to be available. From July 1996 to January 2001, we have implanted 213 porcine stentless valves: the Toronto SPV (159), the Freestyle (20), and the Prima Plus (34) (current IDE). Fifty-five percent of these patients had concomitant coronary artery bypass graft procedures, 44% had isolated aortic valve replacements, and 3 patients required aortic valve and mitral valve procedures. Fifty-nine percent of the patients were men, 9% of procedures were reoperations, and 22% of patients were in New York Heart Association classification III or IV preoperatively. Extubation occurred within 5 hours for 52% of patients, median cardiothoracic intensive care unit length of stay was 1 day, and postoperative length of stay was 6 days. Reoperations for bleeding occurred in 5.3% of patients (0 in the past 12 months), atrial fibrillation in 28.2%, and permanent neurologic deficit in 1.9%. No patients required valve-related reoperations or had either sepsis or sternal infections. Operative mortality was 1.4%. We have also analyzed a subset of patients who had minimally invasive aortic valve replacement versus the standard approach and found no important differences in mortality (none), postoperative complications, cardiopulmonary bypass, or cross-clamp times. There was a trend towards earlier ambulation, less atrial fibrillation (15.8% v 24.1%), and earlier hospital discharge (5.6 days v 7.2 days). We conclude that excellent results were obtained with all 3 stentless aortic valve bioprostheses. Hospital events should be predictably low in elderly patients and those requiring concomitant procedures. Stentless aortic valve bioprostheses can be incorporated into regular cardiac surgical practice with the techniques described.     

Aortic Valve Replacement with Stentless Porcine Bioprostheses

Aortic valve replacement with stentless porcine valve should provide superior hemodynamic results to stented porcine valve because the obstruction caused by the stent and the sewing ring is eliminated. In addition, the coronary sinuses of the recipient may allow for better dissipation of the mechanical stress to which the leaflets are subjected during diastole, thus enhancing durability of the heterograft. Aortic valve replacement with stentless glutaraldehyde-fixed aortic porcine bioprosthesis was carried out successfully in six young sheep. These animals were hemodynamically evaluated at 3 to 6 months after operation and found to have no resting gradients or any degree of aortic regurgitation. Explantation of the aortic heterograft revealed that it was well healed in the aortic root and had no evidence of any calcification. A clinical trial has been initiated and the results in the first five humans who underwent aortic valve replacement with a stentless porcine aortic bioprosthesis have been satisfactory.     

Composite stentless valve with graft extension for combined replacement of the aortic valve, root and ascending aorta.

OBJECTIVE: The composite mechanical valve conduit has been most commonly used for patients who require combined aortic valve, root, and ascending aorta replacement, but is limited, especially in the elderly, because of the need for long-term anticoagulation. We report the first consecutive series of patients in whom a composite stentless valve with graft extension, which does not require long-term anticoagulation, was performed. METHODS: Between April 1998 and July 2000, eight patients with severe aortic root and ascending aortic pathology underwent a combined aortic valve, root, and ascending aorta replacement with a Freestyle stentless porcine valve with a Hemashield graft extension. Mean age was 74 (range 56--82), three were males. Concomitant procedures included coronary artery bypass graft (CABG) alone (n=2), mitral valve replacement with atrial septal defect repair (n=1) and CABG with septal myomectomy (n=1). RESULTS: Operative mortality was zero. Median aortic cross-clamp and cardiopulmonary bypass times were 150 and 203 min, respectively. Two patients returned to the operating room for bleeding. Median blood transfusions and hospital length of stay were 4 units and 11 days, respectively. CONCLUSIONS: The composite stentless valve with graft extension is a reasonable alternative to a mechanical valve conduit for patients who require a combined aortic valve, root, and ascending aorta replacement, in whom anticoagulation is not desirable or contraindicated.     

Outcomes and hemodynamics after aortic valve replacement: a comparison of stentless versus mechanical valves.

PURPOSE: Some investigators suggest that hemodynamic outcomes may be superior with the stentless aortic bioprosthesis when compared with a mechanical valve. The goal of this study was to characterize outcomes and hemodynamic data associated with each type of valve. SUBJECTS AND METHODS: Patient outcomes and echocardiographic data were compared between 25 patients with stentless valves and 59 patients with mechanical valves. RESULTS: There were no significant differences in survival and freedom from cardiovascular adverse events between two groups. The duration of anticoagulation therapy was limited to 3 months in the stentless group. There was no significant difference in preoperative and postoperative New York Heart Association (NYHA) status when comparing the two groups, and NYHA status significantly improved in both groups (P<0.05). There was no significant difference in the echocardiographic data when comparing the two groups. CONCLUSION: Aortic valve replacement using the stentless valve and the mechanical valve provided good clinical and hemodynamic outcomes. There was no significant difference in these parameters when comparing the two groups. There may be advantages in the limited required duration of anticoagulation therapy of the stentless valve , especially in elderly patients. However, longer follow-up is required before definitive conclusions regarding the benefits of the stentless valve relative to the mechanical valve can be determined.     

Surgical technique of aortic valve replacement for small aortic annulus in elderly patients

Recent reports have shown that aortic valve replacement in elderly patients over 65 years with atherosclerotic aortic stenosis and a small aortic annulus is possible by using a small sized bioprosthesis (Carpentier-Edwards pericardial valve). Here we present out surgical technique. Firstly, the native calcified aortic valve was removed completely to gain total exposure of the surrounding aortic root and sinus of Valsalva like Bentall procedure. Secondly, a small sized bioprosthesis was implanted with intermittent noneverting mattress 2-0 sutures with spaghetti and small polytetrafluoroethylene (PTFE) felt. Aortic annulus is the dilated by inserting Hegar dilator sizing from 25 to 27 mm. Therefore, aortic valve replacement for small aortic annulus in intra- or supra-annular position should be easily accomplished. Good surgical results and hemodynamic state were achieved in 25 consecutive cases using this technique.     

Preassembled stentless valved-conduit for the replacement of the ascending aorta and aortic root

Here we report the early clinical results of a new preassembled stentless valved-conduit incorporating artificial sinuses of Valsalva (BioValsalva). This new composite conduit incorporates a stentless porcine aortic valve (Elan, Vascutek Terumo, UK) suspended within a triple-layered vascular conduit (Triplex, Vascutek Terumo, UK) constructed with sinuses of Valsalva. Between December 2006 and January 2008, 17 patients with the mean age of 65 years underwent aortic valve, root and ascending aorta replacement with the BioValsalva valved-conduit. There was no perioperative mortality. There were no myocardial infarctions, cardiac failure or cerebrovascular events. Mean cardiopulmonary bypass time was 156+/-56 min and ischemic time was 112+/-33 min. Eight patients required deep hypothermic circulatory arrest for additional distal ascending aorta replacement. Mean mediastinal drainage was 499+/-262 ml. Postoperative transthoracic echocardiography and CT-scans of the aorta in all patients before discharge demonstrated well-functioning prosthetic aortic valves with small residual mean gradients, no regurgitation, and the presence of sinuses of Valsalva. In conclusion, the novel prefabricated, composite stentless valved-conduit BioValsalva possesses excellent hemodynamic performance and can be implanted with low morbidity. In addition, the conduit material has good hemostatic properties which reduced bleeding, and is easy to implant with a variety of surgical techniques.     

Upper mini-sternotomy for aortic valve operations

Objective : To review our experience in using an upper mini-sternotomy approach to aortic valve surgery. Materials and methods : Nineteen consecutive non-selected patients (15 males, mean age 66 years) underwent isolated aortic valve replacement using an upper mini-sternotomy approach. Twelve patients had isolated aortic valve stenosis, four patients had isolated aortic valve incompetence and three patients had mixed aortic valve disease. Results : In all cases, an excellent view of the aortic valve was obtained, aortic valve replacement was performed and no intra-operative difficulties were encountered. Mean aortic cross-clamp time was 83 min and mean cardiopulmonary bypass perfusion time was 97 min. All patients except two were extubated in the operating theatre and there were no major postoperative complications. Mean hospital stay was 4 days. There were no late complications. Conclusions : Aortic valve surgery can be performed, in the conventional manner and using standard surgical instruments, through an upper mini-sternotomy with no alteration to cardiopulmonary bypass or myocardial protection routines.      

Truly stentless molded autologous pericardial aortic valve prosthesis with single point attached commissures in a sheep model.

OBJECTIVE: Aortic valve cusp extension and free-hand aortic valve replacement with autologous pericardium has been described. The long-term results were shown to be comparable with commercially available aortic bioprostheses. Nevertheless the relatively demanding surgical technique could not find wide acceptance. We developed a new design of a molded aortic valve, fashioned from autologous pericardium, treated briefly with glutaraldehyde, and simplified the implantation technique using single point attached commissures (SPAC). METHODS: Molded autologous valve prostheses were implanted in the subcoronary aortic position in 10 sheep with the commissures connected to the aortic wall at three single commissural points (SPAC). The prosthesis mean size was 21.6+/-1.3 mm and the construction time (excluding 10 min glutaraldehyde treatment) was 6.2+/-1.2 min. Cardiopulmonary bypass and cross-clamp time was 111.1+/-12.4 min and 75.0+/-16.3 min, respectively. Six sheep were euthanized after 201.2+/-10.3 days (6 months) and four sheep were euthanized after 330.8+/-6.5 days (11 months) postoperatively. RESULTS: In all sheep, the valve was immediately competent. At sacrifice, SPAC has proven to be well anchored to the aortic wall and the pericardial valve to be pliable in all cases. The maximum transvalvular gradient after cardiopulmonary bypass and at sacrifice was 3.7+/-2.2 mmHg and 10.6+/-5.2 mmHg, respectively. CONCLUSIONS: This new truly stentless molded autologous aortic valve with simplified implantation technique (SPAC) makes a reliable implantation in a standard timeframe possible. The simplicity of construction, low cost and absent need for anticoagulation of this molded autologous aortic bioprosthesis offers an attractive alternative and not only for patients in the developing world.     

Modified Commando operation using stentless aortic bioprosthesis

Operations necessitating intervalvular fibrous body reconstruction in patients with extensive endocarditis are referred to as “Commando operations,” an indicator of the procedure's difficulty. Aortic root replacement is inevitable when performing the Commando operation for extensive aortic annular defect after radical debridement. We performed a modified Commando operation, in which supra‐annular aortic valve replacement with the Solo Smart stentless bioprosthesis was employed instead of aortic root replacement. Supra‐annular implantation can spare damaged annular structures. This modification is expected to render complex reconstructive surgery technically less demanding.     

Aortic Valve Replacement with Stentless Porcine Bioprostheses

The implantation of stentless porcine valves (SPVs) is technically more demanding than implantation of stented bioprosthetic valves. Implantation of the Toronto SPV bioprosthesis requires an,understanding of the relationships between the leaflets and the aortic annulus and sinotubular junction. In addition to proper alignment of the three commissures within the aortic root, the diameter of sinotubular junction should not exceed the external diameter of the porcine aortic valve after completion of the operation. The Medtronic Freestyle porcine aortic root bioprosthesis can be used for subcoronary implantation as well as for aortic root replacement. Degenerative calcification of a tricuspid aortic valve is the most common cause of aortic valve disease in older patients. Implantation of stentless valves in the subcoronary position is usually feasible because the geometry of the aortic root is well maintained in these patients. The bicuspid aortic valve is the second most common cause of aortic valve disease in older patients and the most common in younger patients. These patients frequently have dilated aortic root, and the Medtronic Freestyle bioprosthesis is ideal for implantation using the root inclusion technique. Stentless porcine bioprostheses are minimally obstructive and associated with low mean systolic gradients. In addition, they have better hemodynamic performance during exercise than stented bioprostheses. For these reasons, patient-prosthesis mismatch has not been described with stentless valves. Left ventricular function after aortic valve replacement appears to be better with stentless than with stented bioprostheses. Comparative, nonrandomized studies of aortic valve replacement with stented and stentless valves suggest that the risk of cardiac death is reduced with stentless valves and the rates of valve-related complications also appear to be lower. What remains unknown is whether stentless valves are more durable than stented ones.     

Successful aortic root replacement for prosthetic valve endocarditis using the freestyle stentless bioprosthesis: report of two cases

We report two cases of prosthetic valve endocarditis which were successfully treated with aortic root replacement using the freestyle stentless bioprosthesis. Prosthetic valve endocarditis occurred in two patients after aortic valve replacement and modified Bentall operation, respectively. The aortic annulus was severely damaged and left ventriculo-aortic discontinuity was found in both cases. We used the freestyle stentless bioprosthesis, which fits well to the destroyed aortic annulus with left ventriculo-aortic discontinuity, because of its flexibility. Postoperative echocardiography revealed excellent hemodynamic results in both cases. Although the long-term results obtained with the freestyle stentless bioprosthesis, such as resistance to bacterial infection, have not been reported, this prosthesis appears to be very useful for treatment of prosthetic valve endocarditis. We expect that this prosthesis might be a option for PVE as an alternative to a homograft.     

Performance of a stentless xenograft aortic bioprosthesis up to four years after implantation.

Conventional biologic and mechanical prostheses have important limitations with regard to their hemodynamic characteristics and long-term durability. We evaluated the hemodynamic function of a stentless porcine aortic prosthesis in 10 patients by invasive pressure measurements and angiography with videodensitometry 8 +/- 4 days after operation, as well as by Doppler echocardiography 35 +/- 15 months after valve replacement. The early postoperative invasive study revealed a mean gradient of 8 +/- 6 mm Hg across the prosthesis, no regurgitation in eight patients, and mild regurgitation, defined as less than 20% regurgitant fraction, in the remaining two patients. The late postoperative Doppler echocardiographic study revealed a mean gradient across the aortic prosthesis of 6 +/- 3 mm Hg, mean Doppler-derived valve orifice area of 1.8 +/- 0.6 cm2, and color Doppler flow velocity mapping suggested no regurgitation in eight patients and mild regurgitation in two patients corresponding to early postoperative angiography. None of the 10 patients received anticoagulation therapy. The clinical course of all patients was without incident. This stentless aortic bioprosthesis may offer hemodynamic advantage; however, further studies are needed to allow comparison with conventional mechanical and biologic prostheses.     

Survival after stentless and stented xenograft aortic valve replacement: a concurrent,controlled trial

BACKGROUND: To define the impact of stentless versus stented valve design on survival late after xenograft aortic valve replacement, a retrospective analysis of all consecutive patients operated on between January 1992 and April 2000 was undertaken. METHODS: Two hundred ninety-two patients had stented (group 1) and 376 stentless (group 2) xenograft aortic valve replacements. Age was older in group 1 (75 +/- 4 vs 70 +/- 7 years, p = 0.01), whereas male gender and aortic stenosis were equally prevalent. Advanced New York Heart Association class III-IV (85% vs 78%, p = 0.03) and associated procedures (53% vs 41%, p = 0.01) were more common in group 1. Aortic cross-clamp (80 +/- 28 vs 96 +/- 23 minutes, p = 0.01) and bypass (91 +/- 56 vs 129 +/- 34 minutes, p = 0.01) times were shorter in group 1. Logistic regression and Cox proportional hazard methods were used to define the role of demographic and operative variables on hospital and late survival, freedom from valve-related mortality, and reintervention. RESULTS: Early mortality was higher in group 1 (6.2% vs 2.6%, p = 0.02). Smaller aortic anulus (p = 0.008), aortic cross-clamp (p = 0.03), and coronary disease requiring bypass (p = 0.03) were associated with hospital mortality. During follow-up (37 +/- 30 vs 43 +/- 35 months, p = NS), 66 late deaths were recorded (12% vs 9%, p = NS). At 8 years, survival (70 +/- 5% vs 81 +/- 3%, p = 0.01), freedom from cardiac- (85 +/- 1% vs 92 +/- 3%, p = 0.02), and valve-related death (79 +/- 5% vs 95 +/- 2%, p = 0.004) were higher in group 2. Freedom from structural deterioration was similar (92 +/- 5% vs 93 +/- 3%, p = NS), but freedom from reoperation was lower in group 2 (99 +/- 1% vs 90 +/- 4%, p = 0.009). Multivariate analysis showed female gender (p = 0.02), age (p = 0.03), and smaller valve size (p = 0.05) to be associated with late mortality; age (p = 0.06) and diagnosis of aortic stenosis (p = 0.008) with cardiac mortality; longer intensive care unit stay (p = 0.001) and stented xenografts (p = 0.05) with valve-related mortality; and younger age (p = 0.01) and stentless xenograft (p = 0.05) with reoperation. CONCLUSIONS: Use of stentless xenografts correlates with better survival and freedom from cardiac- and valve-related mortality than stented valves. However, bias favoring stented valves in older and sicker patients exists. Selective survival advantage of stentless xenograft is confined to valve-related mortality. Stentless valves are more likely to be replaced for dysfunction.     

Hemisternotomy approach for aortic and mitral valve surgery

After exploring several less invasive approaches for cardiac valve surgery, we have concluded that the partial upper sternotomy is the incision of choice for minimally invasive aortic and mitral valve surgery. From March 1997 to January 1999, 827 patients had cardiac valve surgery using this approach; 462 had mitral valve procedures and 365 had aortic valve procedures. Of those having mitral valve surgery, 87% had mitral valve repair. Aortic valve surgery included replacement with stented bioprostheses (38%), allografts (29%), and mechanical prostheses (10%); in addition, 23% had aortic valve repair. Operative mortality was 0.8%. Conversion to full sternotomy was necessary in 2.4%. Blood use was low with 80% of patients receiving no blood transfusions. We conclude that all primary mitral and aortic procedures can be accomplished safely via partial upper sternotomy.     

Placement of a rapid deployment aortic valve in a patient with severely calcified aortic root homograft

Significant aortic calcification is a known sequelae of homograft aortic root replacement and creates a treatment challenge if these patients require cardiac reintervention. The standard surgical option for patients requiring an aortic valve replacement in the setting of a calcified aortic homograft has been a Bentall procedure, which is high-risk with extended cross-clamp, cardiopulmonary bypass and operative times. We present a patient with a severely calcified aortic homograft who underwent successful valve replacement using a rapid deployment aortic valve leaving the aortic root and arch intact and avoiding the more extensive redo aortic root replacement. Similar cases in the literature are rare.     

Stentless porcine and pericardial valve in aortic position.

Fifty-seven patients underwent aortic valve replacement with a stentless glutaraldehyde-fixed bioprosthesis; 27 received a porcine aortic valve and 30 had a bovine pericardial valve. Two groups of 30 patients each who had aortic valve replacement with a tilting-disc mechanical valve or a stented porcine bioprosthesis served as controls. There were no differences in sex, body surface area, valve lesion, and valve size among the four groups. Results were assessed on a Doppler-based determination of maximum velocity across the valve, aortic valve area, and degree of valve regurgitation. Velocity across the valve was significantly less with stentless pericardial valves than with stentless porcine valves, stented bioprostheses, and mechanical valves. Stentless valves had a significantly larger aortic valve area when compared with stented valves. Mild central aortic insufficiency was detected more often with stentless pericardial than with stentless porcine bioprostheses (p = 0.04). Stentless valves showed a higher incidence of complete atrioventricular block when compared with stented valves (p = 0.04). Long-term studies are now warranted to assess the durability of both types of stentless valves.     

Aortic valve disease with severe ventricular dysfunction: stentless valve for better recovery

BACKGROUND: Stentless bioprostheses and homografts show better hemodynamic profiles compared with conventional stented bioprostheses and mechanical valves. Few data are available on stentless aortic valve implantation for patients with severe left ventricular dysfunction. The aim of this retrospective study was to assess the potential benefits of stentless aortic valve implantation for patients undergoing isolated aortic valve replacement with left ventricular ejection fraction < or = 35%. METHODS: From November 1988 through March 2000, 53 patients (45 men and 8 women, aged 64.2 +/- 15.2 years) with a LVEF < or = 35% (mean EF, 28.7 +/- 5.4%) underwent isolated, primary aortic valve replacement for chronic aortic valve disease. Twenty patients received stentless aortic valves and 33 patients received conventional stented bioprostheses and mechanical valves. Predictive factors for LVEF recovery at echocardiographic follow-up (36.2 +/- 32.1 months) were analyzed by simple and multiple regression analysis. RESULTS: There were no significant differences between groups in early and late mortality. Stentless aortic valve implantation required a longer aortic cross-clamp time (p = 0.037). The stentless aortic valve group showed a better LVEF recovery (p = 0.016). Stentless aortic valves had a larger indexed effective orifice area compared with conventional stented bioprostheses and mechanical valves (p < 0.0001). A smaller indexed effective orifice area (p = 0.0008), chronic obstructive pulmonary disease (p = 0.015), and implantation of a conventional stented bioprosthesis or mechanical valve (p = 0.016) were related to reduced LVEF recovery by univariate analysis. A larger indexed effective orifice area (p = 0.024) was an independent predictive factor for a better LVEF recovery by multivariate analysis. CONCLUSIONS: Stentless aortic valve implantation for patients with severe left ventricular dysfunction, even if technically more demanding, is a safe procedure that warrants a larger indexed effective orifice area leading to an enhanced LVEF recovery.