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Page 6 of 15 Troncone et al. Vessel Plus 2023;7:14 https://dx.doi.org/10.20517/2574-1209.2023.08

possibility of the circulatory mixing point being in the aortic arch, raising the risk of retrograde embolism
despite competing antegrade cardiac output. This could potentially be monitored with the use of right and
left radial arterial lines, assessing for the loss of pulsatility in the left radial as a potential indicator that the
left subclavian artery was no longer receiving inflow from native pulsatile flow, and that the mixing point
had become more proximal. However, the combination of right axillary and femoral arterial access may
both improve the safety and simplify the cooling and re-warming phases, as it would permit the use of
antegrade axillary flow for cooling, reducing the risk of retrograde atheroembolism associated with
retrograde femoral flow. Additionally, the ability to have retrograde femoral arterial flow may be beneficial
both during DHCA for the proximal anastomosis with distal aortic clamping as well as the completion of
visceral vessel incorporation, to maintain spinal cord collateral and lower body perfusion. Once all
anastomoses are complete, re-warming can be still accomplished with the use of the antegrade axillary
arterial line, once again avoiding the risk of retrograde embolization.

Regarding the performance of the proximal aortic anastomosis, both aortic clamp techniques and open
aortic approaches with DHCA can increase the risk of neurologic complications from both embolism and
hypoperfusion. While straight DHCA has been used with good outcomes in various cardiac surgical
procedures, it is commonplace to supplement DHCA with additional methods of cerebral protection,
classically in the form of antegrade or retrograde cerebral perfusion, to both increase the safe duration of
circulatory arrest as well as potentially reduce post-operative neurologic complications. These techniques
are easily implemented during cases involving standard median sternotomies, as it allows access to the base
of the innominate artery for permitting antegrade cerebral perfusion from the right axillary artery, as well as
access to the superior vena cava for retrograde cerebral perfusion. While it has been postulated that the risk
of stroke associated with DTA/TAAA repairs is related to atheroembolic debris from arch clamping, large
analyses between these types of cases treated with aortic cross-clamping or DHCA did not reveal a
[8]
difference in post-operative stroke rates . It can be inferred from these studies that the risk of stroke may be
multifactorial, both from embolic causes in the case of arch clamping, as well as global hypoperfusion in
relation to the use of DHCA. Thus, it remains an attractive option to potentially supplement DHCA with
other adjunctive forms of cerebral protection conventionally used for central aortic repairs via sternotomy;
however, there are anatomic challenges given the left thoracotomy exposure used for DTA/TAAA repairs.
Regarding selective antegrade cerebral perfusion, there are multiple described techniques of delivering
antegrade cerebral perfusion during DHCA from the left thoracotomy incision once the proximal aorta is
opened via the insertion of balloon-tipped occlusion catheters into one or both innominate and left carotid
arteries . In this retrospective analysis of 30 patients to assess antegrade cerebral perfusion for DTA/TAAA
[33]
repair, total circulatory arrest time independent of adjunctive cerebral perfusion remained the only
identifiable risk factor for post-operative neurologic dysfunction, with no correlation identified between the
[33]
use of antegrade cerebral perfusion and neurologic sequelae . While maintaining cerebral perfusion may
mitigate the risk of global hypoperfusion associated with DHCA, and while circulatory arrest may abrogate
the risk of atheroembolism with aortic clamping, these described methods of achieving antegrade cerebral
perfusion require both manipulation of the arch vessels with placement of catheters, as well as the potential
for “sandblasting” effects of perfusion velocity jets from catheters into the cervical vessels, both of which
may actually increase the risk of embolic phenomena. In lieu of this, it has been suggested that the use of
retrograde cerebral perfusion may serve to reduce the risk of neurologic sequelae by flushing the cerebral
vasculature of both air and embolic debris. Once again, retrograde cerebral perfusion is an established
technique for surgical approaches via midline sternotomy with facile access to the superior vena cava,
however it is more difficult to achieve this from the left thoracotomy position. In their retrospective analysis
of 189 patients undergoing DTA/extent I/extent II TAAA repairs, Bavaria described their technique of
combining retrograde cerebral perfusion with DHCA for cerebral protection. They either directly
cannulated the inferior vena cava at the inferior cavoatrial junction from the left thoracotomy or inserted a