Aortic valve replacement with medtronic freestyle bioprosthesis: operative technique and results

Systemic Semilunar Valve Replacement in Pediatric Patients Using a Porcine, Full-Root Bioprosthesis

BACKGROUND

Management of systemic semilunar valve disease in growing, young patients is challenging. When replacement is necessary, use of a pulmonary autograft is sometimes not possible for anatomic, pathologic, or technical reasons or due to parental or patient preference. We employed a stentless, porcine, full-root bioprosthesis in this setting and report our outcomes.

METHODS

Over 9 years (2005 to 2013), 24 patients of mean age 13.1 years (range, 3 months to 20.3 years) underwent operation for mixed stenosis and insufficiency in 16 of 24 (67%), pure insufficiency in 7 of 24 (29%), and pure stenosis in 1 of 24 (4%). Twenty patients had previous interventions of repair or replacement, valvuloplasty, or multiple operations. Survival, follow-up echocardiographic findings, and outcomes were documented. All patients were maintained on daily aspirin.

RESULTS

There were no hospital deaths and no early or late deaths over a mean follow-up for 23 patients of 46.1 months (range, 14 months to 9.2 years). One patient moved abroad and was lost to follow-up. Echocardiographic follow-up (mean 34.0 months) demonstrated that no patient developed more than mild insufficiency or moderate stenosis. In total, 20 of 24 (83%) showed no insufficiency and 11 of 24 patients (46%) showed no stenosis. Near or complete normalization of left ventricular mass and dimension was demonstrated. There were no explants and no thromboembolic or bleeding events.

CONCLUSIONS

When use of a pulmonary autograft is not an option, the porcine full-root bioprosthesis appears favorable for systemic semilunar valve replacement in the pediatric and young adult population. Of note, when prosthetic degeneration does occur, stenosis predominates rather than insufficiency. Longer term studies are warranted.

The freestyle aortic bioprosthesis: a systematic review

BACKGROUND

The Medtronic Freestyle bioprosthesis (FSB) provides an alternative to other prostheses for both aortic valve and aortic root surgery. This paper is a systematic review of the post-operative outcomes in patients with aortic valve and/or aortic root disease following FSB implantation.

METHODS

Electronic databases were searched for primary analysis, prospective randomised studies comparing the FSB with an alternative aortic prosthesis were included. Additionally, case series that included data for at least 100 individual operated patients were used for secondary analysis.

RESULTS

Among three identified randomised studies, 199 FSB cases were compared with homografts, and stented and an alternative stentless bioprosthesis. The FSB showed comparable hospital mortality (4.5% vs. 5.3%) and eight-year actuarial survival (80±5.0% versus 77±6.0%) with the homograft (respectively) and comparable reduction in left ventricular mass index relative to other prosthesis types. Over 6000 individual patients were included in the selected 15 case series. Weighted mean operative mortality, neurological event rate and five-year actuarial survival was 5.2%, 5.5% and 77.8%, respectively.

CONCLUSION

The FSB performed comparably against alternative prostheses regarding in-hospital mortality, long-term survival and reduction in left ventricular mass index. Included case series demonstrated robust post-operative outcomes in both the short and long term.

Risk in elderly patients after stentless versus stented aortic valve surgery

Recent studies suggest that the hemodynamic advantage of stentless bioprostheses over the stented type improves long-term survival after aortic valve replacement, but the more complex and time-consuming implantation technique may increase the risks of operative death and postoperative complications. Between April 1996 and June 2001, 519 patients with a mean age of 76 +/- 5 years underwent aortic valve replacement using a stentless (Medtronic Freestyle, n = 277) or stented bioprosthesis (Medtronic Mosaic, n = 242). Multiple logistic regression analysis considering different patient populations revealed no increased risk of operative death, postoperative complications, or neurological impairment after implantation of a stentless bioprosthesis. Survival curves in respect of 367 patients who underwent aortic valve replacement up to September 2000 and were followed up for 3 years were not different (p = 0.98). As the patients were elderly, improved survival due to implantation of a stentless valve could not be demonstrated within this time span.

Aortic valve replacement with the freestyle stentless bioprosthesis with respect to spacial orientation of patient coronary ostia

OBJECTIVE

This study evaluates our results for safety and efficacy of aortic valve replacement using the Freestyle bioprosthesis (Medtronic, Inc, Minneapolis, Minn) with a new modified subcoronary implantation technique. This technique takes into account the spacial orientation of the stentless bioprosthesis in the aortic root with respect to the patient's coronary ostia rather than the native commissures.

METHODS

Fifty-two consecutive patients with predominant aortic valve stenosis underwent aortic valve replacement with a Freestyle bioprosthesis by means of the described modified subcoronary technique over a 15-month period. Fifty of them were followed up by means of echocardiography at discharge, 6 months, and 1 year. There were 19 men and 31 women, with a mean age of 76 +/- 7 years (range, 58-87 years). Valve size ranged from 21 to 27 mm.

RESULTS

Patients with bicuspid aortic valves had a significantly larger angle between both coronary ostia than patients with tricuspid aortic valves (P =.0001). The peak and mean systolic gradients decreased significantly during the first postoperative year for each valve size (P </=.001), and the effective valve areas increased significantly during this time interval for each valve size (P </=.01). Only 13 patients had aortic insufficiency at discharge, which was trivial in 9 and mild in 4 patients. The prevalence of trivial aortic insufficiency decreased during the first postoperative year, and that of mild aortic insufficiency remained unchanged. The sinotubular junction diameter was significantly greater than that of the aortic anulus for each valve size before operation (P <.001). The sinotubular junction diameter decreased significantly after aortic valve replacement and remained unchanged during the first postoperative year for each valve size (P <.001).

CONCLUSIONS

Aortic valve replacement with the Freestyle bioprosthesis using the modified subcoronary technique, which takes into account the spacial orientation of the patient's coronary ostia, has hemodynamic results similar to those of other series with different subcoronary implantation techniques. This technique is reproducible, safe at the coronary ostial level, and effective in accommodating variability in angles between human coronary ostia, ranging from 130 degrees to 170 degrees. Moreover, the great preoperative discrepancies between aortic anulus and sinotubular junction diameters are corrected immediately after operation.

Medtronic Freestyle aortic root bioprosthesis: Implant techniques

BACKGROUND

The Medtronic Freestyle aortic root bioprosthesis is a complete porcine aortic root to allow implantation (1) as a subcoronary valve replacement by removing graft sinus aorta, (2) as a cylinder with the sinotubular junction intact within the aorta (root inclusion), or (3) as a complete aortic root replacement. The choice among the three implant techniques depends on surgeon preference or upon the pathology encountered. The advantages and differences among the three implant techniques are examined.

METHODS

The Medtronic Freestyle bioprosthesis was implanted in 1163 patients in a Food and Drug administration (FDA) clinical trial between August 1992 and October 1997. There were 21 centers in the international trial using a single data repository. Clinical data was collected prior to and at operation, at 3 to 6 months and annually. The data were compiled and statistical analysis performed at the data center.

RESULTS

Patients having subcoronary valve implants were older (80% > 65 years) and aortic occlusion time was about 20 minutes less than the other methods. Patients having aortic root replacement presented with more aortic valve insufficiency (20%). Pathology of the aortic root and ascending aorta requiring repair was 26%, and larger (27 mm) valves were used in 40% of patients. Risk of operation was lowest (5.0%) with subcoronary valve implants and highest (11.7%) with root replacement technique. Thromboembolism was higher, early and late, with root inclusion (3.0, 3.9%/patient per year) and root replacement (3.2, 3.0%/patient per year) than for subcoronary implants (1.8, 1.6%/patient per year). There were more patients taking warfarin at the 4-year point with root inclusion (20%) or root replacement techniques (24%) than among patients having subcoronary implants (14%). Explants of the valve occurred in 2% of patients, none of whom had aortic root replacement.

CONCLUSIONS

The Medtronic Freestyle bioprosthesis is an effective and versatile device for replacement of the aortic valve. It offers implant techniques that can treat the aortic root pathology encountered at surgery and allows the operation to proceed according to surgeon preference.