4.1: Graft Oozing
It is worth emphasising that oozing from the graft portion of E-Vita
Open NEO is not a phenomenon unique to Ho et al. Rather, it is a
well-documented complication associated with use of the device that
surgeons, as pointed out by Ho et al., should expect rather than simply
be aware of.8,10 In their study detailing initial
experiences with E-Vita Open NEO in the Asia-Pacific region, Jakob et
al. highlight a case of graft oozing during FET surgery in a 54-year-old
male with ascending aortic aneurysm and type B aortic
dissection.10 Oozing from the polyester segment
persisted following protamine administration and CPB weaning, and
eventually required liberal amounts of Surgicel®
FibrillarTM (Johnson and Johnson N.V., Belgium) with
pressurised packing for several minutes to be
controlled.10 Further, Czerny et al. also highlight
three cases of profound graft oozing during E-Vita Open NEO
implantation, following CPB weaning and protamine
administration.9 Routine substitution of plasmatic and
cellular coagulation, guided by thromboelastometry, was unsuccessful in
controlling graft oozing. One patient required 23U of red blood cells,
28U of fresh frozen plasma, and 16U of thrombocytes within the first 24
hours postoperatively. All three patients had complicated postoperative
courses, involving low cardiac output necessitating inotropes,
haemodialysis, multi-organ failure, paraplegia, and
death.9 A recent systematic review by Bashir et al.
also concluded that reports on post-FET coagulopathy were associated
with substantially higher heterogeneity in E-Vita Open NEO® and Cronus®
compared to Thoraflex® and Frozenix®.12 It is possible
that reports on perioperative coagulopathy associated with E-Vita Open
NEO® would encompass cases wherein graft oozing lead to a need for
increased blood product transfusion, or reintervention to correct
bleeding.12
The risk of graft oozing in FET for TAR is likely governed by surgical
and non-surgical factors. Modern surgical techniques, low graft
porosity, advanced suture material, and anastomotic adjuncts used to
support suture lines (e.g., BioGlue) all serve to greatly diminish the
likelihood of graft oozing. In contrast, the lack of gelatine and
collagen impregnation in E-Vita Open NEO has likely re-introduced the
risk of graft oozing due to massively increased graft
porosity.9 This is unsurprising considering there have
hitherto been no reports of graft oozing from market equivalents (i.e.
Thoraflex®, Frozenix®, and Cronus®) that do feature gelatine and
collagen impregnation. Non-surgical factors, such as routine use of
thromboelastometry, allow continued monitoring of the patient’s
intraoperative thrombotic state and enables rapid intervention against
aberrant haemodynamics or coagulopathy.9Interestingly, Ho et al. point out that graft oozing mostly occurred in
patients presenting with abnormal TEM findings.8 It is
unclear why E-Vita Open NEO® is not impregnated with collagen or
gelatine, especially considering this seems to be a standard feature in
similar commercially available devices, and that abnormal thrombotic
states are not rare pre-operative characteristics in patients undergoing
aortic surgery.