Apical closure device for full-percutaneous transapical valve implantation: stress-test in an animal model†

Transapical valve implantation is traditionally performed through a left antero-lateral mini-thoracotomy. A self-expandable apical closure device has recently been developed for full-percutaneous transapical valve implantation. We performed haemodynamics stress-tests on an animal model to evaluate the sealing properties.

Under general anaesthesia 5 pigs (mean weight: 67 ± 6 Kg) received full heparinization (100 IU/Kg; activated clotting time >250 s and, through inferior mini-sternotomies, 21-Fr introducer sheaths for transapical aortic valve implantation (outer diameter: 25-Fr) were placed over-the-wire in the apexes. Delivery-catheters carrying folded occluders (SAFEX TM final design) were inserted in the introducer sheaths and plugs were then deployed under fluoroscopic guidance. Phase 1: after protamine injection, apical bleeding was monitored for 1 h with standard haemodynamics condition. Phase 2: we induced systemic hypertension with adrenaline infusion to test the sealing properties under stress. Animals were sacrificed after Phase 2 and hearts were removed and inspected.

Five plugs were successfully introduced and deployed in 5 pig hearts. Plugs provided good apical sealing in each animal and a mean of 7 ± 4 ml of blood lost per animal was collected during Phase 1: haemodynamics remained stable and no plug dislodgement was detected (mean blood pressure: 52 ± 9 mmHg). During Phase 2, mean systolic and diastolic peak levels reached 268 ± 24 mmHg and 175 ± 17 mmHg, respectively, without plug dislodgment or bleeding. Post-mortem inspection showed good plug deployment and fixation without myocardial damage.

The new apical occluder seals large-sized apical access sites in animal models also during induced systemic hypertension. This pilot study is a further step towards full-percutaneous transapical valve procedures in the clinical setting.