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Troncone et al. Vessel Plus 2023;7:14 https://dx.doi.org/10.20517/2574-1209.2023.08 Page 3 of 15

complications, including intraoperative pulmonary artery catheter pressure recordings, transesophageal
echocardiography, as well as placement of a left inferior pulmonary vein vent which can both augment
venous drainage as well as decompressing the left ventricle. However, there is a paucity of patient factors
that have been assessed as favorable or prohibitive for DHCA in the repair of DTAs/TAAAs. One such
factor may be obesity, which poses both surgical and perfusion-related challenges on the execution of
TAAA repair. The severity of obesity in relation to CPB is often reflected in both with the body mass index
[BMI] as well as the body surface area [BSA] calculations. Most studies on the safety of various forms of
cardiac surgery, including those utilizing DHCA, have identified elevated BMI as an independent risk factor
for postoperative complications such as myocardial infarction, sepsis, pulmonary and gastrointestinal
[10]
sequelae, as well as overall mortality . While there are numerous additional challenges posed by obesity on
the conduct of CPB, there are some specific challenges related to cases using DHCA. As higher flow rates
are required for larger patients, this necessitates higher venous return, and a much larger venous reservoir
may be required to accommodate the larger circulating volume of these patients during the exsanguination
phase of DHCA . However, there have been no dedicated analyses performed to date looking at the
[11]
implications of obesity specifically on the outcomes of DTA/TAAA repair using DHCA. At this point, there
can be no recommended cut-offs on the applicability of DHCA to the repair of these complex pathologies,
as the more salient technical and clinical factors as detailed above seem to be more impactful.

There are numerous medical adjuncts used in the efforts to improve the safety of performing
thoracoabdominal aneurysm repair with DHCA. One such strategy involves the administration of systemic
corticosteroids, either intravenously or delivered via the CPB reservoir, to improve neurologic outcomes.
There is considerable variation in the literature regarding the timing and dosing of these medications, with
[12]
some advocating administration at least 6-8 h pre-operatively, to their delivery intraoperatively .
Nevertheless, the administration of adjunctive medication, be it corticosteroids or otherwise, is a practice
that is as variable as the institution performing the repair. While there are no robust data on the efficacy of
any of these medical adjuncts for organ protection for the specific repair of DTAs or TAAAs, there is some
[13]
non-human basic scientific evidence in its use for neurologic outcomes after circulatory arrest . Following
this, there have been some clinical studies which have suggested a trend towards improved neurologic
[14]
outcomes with corticosteroid administration in patients undergoing surgical cases requiring DHCA .
However, in a retrospective study of 328 patients undergoing total arch replacement with moderate
hypothermic arrest and selective antegrade cerebral perfusion, administration of large doses of
[15]
methylprednisolone intraoperatively was not associated with any differences in neurologic outcomes . In
lieu of these conflicting data, there can be no formal recommendation of the administration of
corticosteroids for the purpose of end-organ protection during DTA/TAAA repair using DHCA until the
accumulation of more robust clinical evidence.

In addition to its immediate intraoperative and early post-operative negative sequelae as described
previously, the main post-operative concern of DHCA utilization has been on the preservation of
neurologic function following surgery. While there are documented movement disorders as well as reports
of behavior and intellectual changes after both pediatric and adult cardiac surgery using DHCA, there is
little in the literature specifically regarding DTA/TAAA repair. The aortic group at Yale published data on
394 patients undergoing thoracic aortic surgery using straight DHCA as their protection strategy, showing
excellent clinical cognitive outcomes . They went on to publish data on 29 patients from that cohort that
[16]
were, by their definition, employed in careers requiring a high degree of cognitive ability, concluding that
there were no perceptible or quantifiable changes in their cognitive capacity post-operatively, including
[17]
memory function . Overall, there is a robust published amount of data on the overall safety and tolerability
of DHCA for various adult cardiac surgical procedures when used within acceptable margins of time,