Aortic valve replacement: is the stentless xenograft an alternative to the homograft? Midterm results

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.

Midterm Results After Aortic Valve Replacement With a Stentless Bioprosthesis Aortic Valve

BACKGROUND

It is suggested that a simplified implant model Cryolife-O'Brien (CryoLife International, Kennesaw, GA) offers less satisfactory outcome compared with standard stentless models. This study was conducted to prospectively evaluate the midterm results after aortic valve replacement with the Cryolife-O'Brien stentless bioprosthesis.

METHODS

In 1996, a prospective clinical trial using different stentless valves was initiated. From September 1996 through September 2002, 156 consecutive patients with a mean age of 74.5 years underwent aortic valve replacement with the Cryolife-O'Brien porcine stentless bioprosthesis. The predominant aortic valve lesion was stenosis in 128 and insufficiency in 28 cases. Patients have been followed from 2 to 72 months (mean, 42 months). Echocardiography was performed by one echocardiographer preoperatively, intraoperatively, postoperatively at discharge, 2 to 6 months later, and annually thereafter.

RESULTS

Sixty percent of patients received a valve 25 mm in diameter or larger; 39% had concomittant coronary bypass grafting. The 30-day operative mortality rate was 6.4%. Ten late nonvalve-related deaths have occurred. Severe aortic insufficiency caused by oversizing leads to early reoperation in 3 patients. The peak and mean systolic gradients decreased significantly during the first 12 months after implantation, p < 0.001, and the effective valve areas increased significantly during this time interval p < 0.001. At 5 years, ten patients have moderate aortic insufficiency. The actuarial survival at 5 years was 88 +/- 3%. The rate for freedom from endocarditis was 100% and for freedom from thromboembolic events was 94%.

CONCLUSIONS

Midterm results after aortic valve replacement with the Cryolife-O'Brien stentless bioprosthesis are encouraging. Good hemodynamics have been coupled with low rate of valve-related complications, thus representing a very good alternative to conventional stented bioprostheses.

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.

Fate of stentless bioprostheses on right side of the heart

Newly developed stentless bioprostheses have shown good midterm results in the aortic position, but few data are available on their use at the right side of the heart. Four types of stentless bioprosthesis were used for right-side reconstruction of congenital heart anomalies in 50 patients (3 Baxter-Edwards Prima, 27 Medtronic Freestyle, 14 Cryolife Ross, and 6 Medtronic Contegra). Mean age was 9.03 +/- 6.25 years. Serial Doppler echocardiographic studies were performed to evaluate transvalvular pressure gradients. The hospital mortality was 6%. Reoperation was required in 3 patients in the early postoperative period because of left ventricular outflow tract obstruction, endocarditis, or tricuspid insufficiency. Measurements from 34 patients were available for statistical analysis. Clinical follow-up was complete in 43 of the 47 hospital survivors; the mean follow-up period was 16.6 +/- 16 months. Four patients died during follow-up; 93% of the survivors have an unrestricted lifestyle. Although peak transvalvular conduit gradients increased in all types of conduit, no reoperation has yet been performed for conduit stenosis. The newly developed stentless bioprostheses may be a useful alternative for right-side reconstruction of congenital heart anomalies.

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 m(2). 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 m(2), male sex, arterial blood pressure > or = 150 mm Hg, left ventricular ejection fraction < or = 35%, New York Heart Association functional class > or = III, non-sinus rhythm, and prevalent aortic incompetence to be factors influencing LVMR. LVMR was not related to postoperative effective orifice area < or = 0.85 cm/m(2) 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.

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.