On-pump transapical cardioscopic mitral valve replacement with cardiac arrest: short-term results in a porcine survival model.

OBJECTIVES: Favourable outcomes with mitral annuloplasty have been achieved with transapical cardioscopic (TAC) surgery in a survival animal model. In addition, experimental TAC on a non-survival animal model also showed adequate access to remove the native mitral valve and implant a prosthetic valve, but the surgical procedure took a long time and lacked follow-up data. The goal of this study was to develop a clinically translatable TAC mitral valve replacement (MVR) procedure using technical and instrumental refinements to reduce the surgical time and to evaluate functional recovery and short-term durability using a survival porcine model. We hypothesized that MVR could be achieved with subannular implantation of the bioprosthesis via the TAC approach. METHODS: TAC MVR using the Hancock II™ (Medtronic)® mitral prosthesis was performed in 6 pigs via an incision over the xiphoid process, under cardiopulmonary bypass and cardiac arrest. COR-KNOT® and minimally invasive cardiac surgery instruments were used. Haemodynamics, echocardiography, cardiac computed tomography, ventriculography and electrocardiography were used to evaluate the function of the mitral prosthesis and left ventricle, coronary system and conduction system in the perioperative period and 4 weeks later. RESULTS: A postimplant examination showed that the mitral prosthesis was competent, without a paravalvular leak. The left ventricular ejection fraction was comparable to preoperative values (65.2 ± 4.1 vs 67.2 ± 7.9). The bypass, cross-clamp and implant times were 177.2 ± 44.2 min, 135.3 ± 47.6 min and 94.0 ± 41.2 min, respectively. The prosthesis was in a good position. The apical scar was intact and not aneurysmal 4 weeks after the implant. The valve was properly sutured to the annulus, without a postimplant paravalvular leak. All animals recovered after 1 month of follow-up with preserved ventricular function and normal wall motion. CONCLUSIONS: We successfully managed to replace the mitral valve with a biological prosthesis via the apex with encouraging bypass and cross-clamp times. This technique may provide an alternative for a selected group of patients with diseased mitral valves who have indications for MVR and still in a high-risk redo setting with conventional sternotomy or minimally invasive cardiac surgery-MVR.

Comparison of mini-cardiopulmonary bypass system with air-purge device to conventional bypass system.

BACKGROUND: Although mini-cardiopulmonary bypass systems reduce inflammation, hemodilution, and transfusion requirements, the problem of air entrainment and embolization into the system has limited its use. Newer systems incorporate an air purge to address this problem. We compared the benefits and possible risks in using the newer mini-cardiopulmonary bypass system with those for conventional cardiopulmonary bypass. METHODS: Data of 60 patients who underwent cardiac surgery with a newer mini-cardiopulmonary bypass system incorporating an air purge from August 2005 to July 2006 (group A) were retrospectively collected and compared with that of 60 matched patients who underwent cardiac surgery with conventional cardiopulmonary bypass during the same period (group B). Matching criteria were prebypass hematocrit, body surface area, age, and surgical procedure. RESULTS: Demographic and background data were similar for both groups. There were no detectable episodes of air embolism. Patients in group A had higher initial and nadir hematocrits during cardiopulmonary bypass and received fewer transfusions. However, postoperative blood loss and transfusion requirements were similar in both groups. Episodes of low indexed flows during cardiopulmonary bypass commonly occurred in group A, and this was associated with a greater than 50% decrease in urine output and lower mixed venous oxygen saturations (58% +/- 6% versus 68% +/- 5%) as compared with group B. There were no differences in clinical outcomes. CONCLUSIONS: The newer mini-cardiopulmonary bypass system addressed the problem of air embolization. It preserved hematocrit and reduced transfusion during cardiopulmonary bypass, but did not improve outcomes postoperatively. It is unclear whether these benefits outweigh the potential risk of hypoperfusion associated with its use.