DISCUSSION
HP for FET is constantly evolving through the years ever since the first device - ‘Essen I prosthesis’ (2005) (1). Given the success of Evita-open-plus across the globe, researchers have developed the next generation HP: Evita-open-NEO. The new generation prosthesis is available in three variations, making it suitable to be implanted in zone 0 to 3, and the supraaortic-arch-vessels can be reimplanted individually or en-bloc. This provides a wide range of applicablity for the surgeons emcomprising different pathological situations. The low profile delivery system and a shapeable shaft, is atraumatic and helps in precise deployment (2).
Evita-open-NEO prostheses are not impregnated with gelatin or collagen, hence some discrete oozing through pores of the tightly woven polyester during heparinization can be expected but easily controlled by sump suction.
This oozing is self-limiting and stops once the protamine is administered after weaning of cardiopulmonary bypass (CPB) supported by packing the mediastinum with sponges and towels for 10-15 minutes. Blood collected in mediastinum can be efficiently managed with cell saver. In patients who undergo FET under prolonged deep hypothermic circulatory arrest, coagulopathy has to be considered. In that case, graft oozing through the pores may appear excessive but can be quickly fixed by TGCM during and after CPB (Video 1).
Thromboelastometry provides important information about hemostasis, particularly in regard to fibrin polymerization and platelet function, and can already be initiated at crossclamp release. Accordingly, cryoprecipitate can timely be prepared if fibrinogen concentrate is not available. Adequate fibrin and platelet contribution to the clot firmness are essential for the formation of an internal fibrin layer to seal the prosthesis (3). In contrast, low fibrinogen levels (<2-4 g/L) have been shown to be an independent risk-factor for severe bleeding, 24-hour mortality, in-hospital mortality, and neurological complications in patients with acute AD (3- 6).
The algorithm of TGCM for major aortic surgery is by using a trigger of EXTEM A5 <40 mm and FIBTEM A5 <12 mm, and a target of EXTEM A5 ≥40 mm and FIBTEM A5 ≥15 mm for fibrinogen substitution (3, 7). Notably, this can only be achieved by administering fibrinogen concentrate (20 g /l) or cryoprecipitate (8-16 g/l) but not by FFP containing only 2g fibrinogen/l) (8). Some patients require platelet transfusion and/or prothrombin complex concentrate administration in addition.
In contrast, Czerny and colleagues recently reported devastating oozing and severe blood loss in 3 patients after implantation of E-vita open NEO (9). Those patients, characterized by continuous acetylic acid monotherapy preoperatively, obviously mandated differentiated coagulation management during and after CPB. Here, FFP transfusion with its low fibrinogen concentration is certainly not appropriate and may cause pulmonary complications, right ventricular failure, and increased RBC transfusion (10, 12).