Abstract
Background: Aortic stenosis (AS) is the most common valve disease in adults and, worldwide, represents the third cause of cardiovascular disease, preceded by arterial hypertension and coronary artery disease (1). In developed countries the most common etiology of AS is age-related calcific disease. Symptoms of AS are dyspnea, (pre)-syncope and angina (2). For patients with symptomatic and/or severe AS, valve replacement represents the standard and definitive treatment (3). However, elderly patients with severe AS, frequently have relevant comorbidities which preclude a surgical approach for high surgical risk (4). Transcatheter aortic valve replacement (TAVI) is a valid alternative for these inoperable patients(5). At present transapical TAVI (TA-TAVI) is performed through a mini-thoracotomy. New devices need to be developed in order to aspire to less invasive, full-percutaneous procedures for TA-TAVI. Access and, especially, closure of the heart apex remain a challenge in a minimal invasive setting.
Objectives and Methods: The new occluder from Comed (Comed, Bolsward, The Netherlands) was designed to allow full-percutaneous performance of TA-TAVI. It consists in an auto-expandible device for left ventricular apical closure, made of woven Nitinol wires designed in two self-expandable round retention disks with a connecting extendable waist. In our study the device was implanted in five young pigs. In a first phase the device was studied under standard conditions and in a second phase we tested it under stress conditions with growing doses of intravenous adrenaline.
Results: Five plugs were introduced and deployed in five pig hearts with immediate good apical sealing. During phase 1 only traces of blood were collected (mean of 4±5ml of blood lost per animal), hemodynamic parameters remained stable and no plug dislodgement was observed. During Phase 2, mean systolic and diastolic peak levels reached 268±24mmHg and 175±17mmHg, respectively, without plug dislodgment or bleeding. Macroscopic post-mortem analysis of the hearts showed good fixation of the device without myocardial damages.
Conclusions: Our experience with the apical occluder showed good early results under standard conditions as well as under stress conditions. No major bleeding nor device dislocation or embolization was observed and there was no macroscopic myocardial structural damage. The good sealing properties of the plug in its final design also under hemodynamic stress-tests in our animal model gives additional integrity to this emerging access and closure variety for TA-TAVI. To assess the thrombogenicity risk of the inner-disk,
supplementary chronic animal studies need to be performed.