Transcatheter mitral valve repair using the Cardioband® system: Histopathological insights in device ingrowth and biocompatibility
Martin O. Schmiady1*; Mathias Van Hemelrijck1, Maurizio Taramasso2; Juri Sromicki1, Carlos A. Mestres1, and Matthias Sigler3
1Division of Cardiac Surgery, University Heart Center, University Hospital Zurich, Raemistrasse 100, 8091 Zurich, Switzerland
2Heart Center Hirslanden Zurich, Witellikerstrasse 36, 8008 Zurich, Switzerland
3Pediatric Cardiology and Intensive Care Medicine, Georg-August University, Robert-Koch-Strasse 40, 37075 Goettingen, Germany
*Corresponding author: Martin O. Schmiady. Division of Cardiac Surgery, University Heart Center, University Hospital Zurich, Raemistrasse 100, CH-8091 Zurich, Switzerland.
Tel: +41 44 255 95 82; fax: +41 44 255 44 67, e-mail: martinoliver.schmiady@usz.ch
Keywords: Cardioband®, transcatheter mitral valve repair, mitral annuloplasty, mitral regurgitation, biocompatibility, Tissue reaction
Surgical implantation of a complete or incomplete ring to reduce the valve annulus and improve leaflet coaptation is the mainstay of mitral valve surgery. The Cardioband® system (Edwards Lifesciences, Irvine, CA, USA) was designed to address the pathophysiological mechanism of annular dilatation through a catheter-based approach1. We present the histopathological workup of a Cardioband®device, which had been implanted 21 months earlier in a 34-year-old male with ischemic cardiomyopathy and severe functional mitral regurgitation. Starting at the anterolateral commissure, 17 anchors were implanted under general anaesthesia, echo- and fluoro guidance (Panels A and B). A significant reduction in mitral valve regurgitation from severe to trivial was achieved (Panels C and D). Even though the patient’s clinical symptoms improved, he later was listed for transplantation due to the severely impaired left ventricular function (LVEF 15%).
After surgical removal, the device was preserved in formalin and later embedded in a synthetic resin (methylmethacrylate, Technovit 9100, KULZER&Co, Wehrheim, Germany), hardened, and subsequently sectioned in slices of 0.8 mm using a diamond cutter. These slices were ground down to 10-30 µm using a rotational grinder. Standard staining was performed with Richardson blue. An extended histopathological work-up was performed2. On gross examination, the Cardioband® was intact. All anchors were well positioned and firmly attached to the annulus (Panel E). This was also confirmed by histology (Panel F). No superficial deposit of thrombus material was detected. A thin layer of endothelialized pseudointima had formed on the surface of the device.
In summary, we can demonstrate a well-positioned and securely anchored device. The architecture of the valve tissue and the subvalvular apparatus were preserved thus allowing for the combination with other percutaneous reconstructive methods. Screws were firmly anchored and endothelialized, making explantation in case of redo surgery challenging.