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Transcatheter valve replacement: New Concepts for Microsurgery Inside the Heart
Friedrich M.1, Brecht R.1 ,Heinisch P.P.1, Plonien K. 1, Akra B.1, Hagl C.1, Bombien R.2
1 Clinic of Cardiac Surgery, University of Munich - Grosshadern, Munich, Germany 2 Department of Surgery – Vascular and Endovascular Surgery, University of Munich - Grosshadern, Munich, Germany
Objectives. The catheter-based valved stent implantation already became a part of clinical routine. But to refine these procedures and reduce complications, new concepts will be helpful. The aim of this study was to evaluate an intra-cardiac-corporeal circulatory support and a stapler-based concept for aortic valve replacement.
Material and Methods. ActiveFlowModel: The transventricular valve isolation chamber (TVIC) was combined with an intra-cardiac pump (Impella®), and the blood was directly bypassed from the right ventricle into the pulmonary artery. After in-vitro testing (porcine hearts, N=10), the system was evaluated in a porcine beating-heart model (N=1). Before isolation of the valve the intra-ventricular bypass was started. Time of bypassing, ECG, oxygen saturation and blood pressure were recorded. AorticValveReplacementModel: The stapler-based instrument for transapical aortic valve replacement (StapAVR) combines a removal section and an implantation section. The in-vitro evaluation was performed using artificial valves with fluorescent debris. During resection, black-light visualized the debris and their movements. A modified StapAVR was used in-situ in a porcine model (N=4). The resection time and the occurrence of debris were documented.
Results. ActiveFlowModel: The TVIC deployment time in-vivo was 4.6 min±0.8min. Mean bypass flow of 1.2±0.1 l/min during isolation was achieved. Oxygen saturation was a median of 94.4% (range 84- 98). The median arterial blood pressure was 110 mmHg (systolic; range: 80- 150) and 60 mmHg (diastolic; range: 20- 70) without use of inotropes or vasopressores. Sinus rhythm was observed. Isolation time with bypassing was 23±0.7 min. AorticValveReplacementModel: The deployment of the StapAVR in the correct position was performed within 2.0min. The valve resection time was 4.2+/-1.6min. Fluorescent debris was found in the right coronary artery (7%), in the ascending aorta (11%), in the bulbus aortae (35%), and the left ventricle (24%). Valve implantation was performed successful in 3/4.
Conclusion. Active intra-cardiac bypassing during valve-isolation in a beating heart is possible. The next step is the isolation of the aortic valve in a beating heart cycle. The valve replacement with the StapAVR was also possible. Nevertheless, improvements of the prototypes are ongoing. The further development will bring the catheter-based intra-cardiac microsurgery closer to the surgical golden standard.
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