A technique of aortic annulus enlargement with a Freestyle stentless bioprosthesis.

We describe our surgical technique to manage a small aortic annulus during aortic valve replacement. Starting with the posterior annular enlargement incision described by Manouguian, a stentless porcine aortic root, with excision of the left and right porcine coronary segments and conservation of the mural wall (Freestyle MS design, Medtronic, Minneapolis, MN ), was used. The Freestyle bioprosthesis enlarges the aortic annulus using a direct suture of the valve on the enlarged annulus, and the aorta is closed by a direct suture of the mural wall of the bioprosthesis. Therefore, the aortic annulus enlargement is made only using the aortic bioprosthesis, without other material.

Treatment of atrial fibrillation by surgical epicardial ablation: bipolar radiofrequency versus cryoablation.

UNLABELLED: Atrial fibrillation is the most frequent form of cardiac arrhythmia. Its surgical management has improved in recent years with major advances in our knowledge of the underlying pathogenic mechanisms. This has led to simpler therapeutic strategies such as epicardial ablation. The aim of this comparative experimental study was to evaluate the efficacy of this treatment, achieved with either bipolar radiofrequency or cryoablation. MATERIALS AND METHODS: Twelve sheep were used. After left thoracotomy, epicardial ablation of the junction between the left pulmonary veins and the left atrium was achieved by means of bipolar radiofrequency in group A (n=6) and by cryoablation in group B (n=6). Electrical stimulation thresholds were determined before and after ablation. Four weeks after ablation, sheep were killed for pathologic studies. RESULTS: The mean stimulation threshold was 3.5+/-0.6 mA before ablation and 15.6+/-5.6 mA after ablation. The difference was significant in both groups, showing that effective conduction blockade was obtained with the two ablation methods. Histologic studies after radiofrequency and cryoablation showed limited coagulation necrosis and cellular rarefaction, respecting the supportive tissue. CONCLUSIONS: Both methods of surgical ablation by the epicardial route yielded effective electrical isolation of the pulmonary vein junction with the left atrium. This conduction blockade was due to limited coagulation necrosis with myocyte rarefaction, of similar extents in the two procedures. Standardization and refinement of this technique could extend the treatment indications for atrial fibrillation associated with other cardiac disorders that require surgical treatment without opening the left atrium.