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Page 6 of 16 Katz et al. Vessel Plus 2023;7:1 https://dx.doi.org/10.20517/2574-1209.2022.52

Hematological
Because patients undergoing TAAA or DTA repair are at significant risk for hemorrhage, preoperative
hematological analysis is essential. Serum hemoglobin, blood type and screen, platelet count, and measures
of coagulation status - including partial thromboplastin time, prothrombin time, and fibrinogen level -
should be routinely checked preoperatively, including on the day of surgery. Supplemental tests, such as
platelet aggregation to evaluation function, may be indicated in select patients. Any abnormalities should be
corrected before the operation.

The preoperative management of antiplatelet or antithrombotic agents should proceed in accordance with
guidelines from the American College of Cardiology/American Heart Association and the American Society
of Regional Anesthesia, especially in patients who will require a cerebrospinal fluid (CSF) drainage catheter
to prevent procedural complications, such as spinal epidural hematomas . If a patient with a mechanical
[23]
prosthetic valve is taking a vitamin K antagonist, the international normalized ratio (INR) is allowed to drift
down. When indicated, more-rapid correction can be achieved with vitamin K or prothrombin complex
concentrate (KCentra; CSL Behring, King of Prussia, PA).

For elective cases, warfarin is held for a minimum of 9 days preoperatively; enoxaparin is used as a bridge in
selected patients with mechanical valves and is stopped 48 h before surgery. In inpatient cases, an
unfractionated heparin drip will allow for rapid reversal as needed.

INTRAOPERATIVE CONSIDERATIONS
As a high-risk, technically challenging endeavor, TAAA or DTA repair - especially for Crawford extent II
aneurysms - can cause potentially serious complications, such as intraoperative death, paraplegia, and renal
[24]
failure. Protective surgical techniques should be employed to mitigate the extent of injury . Cardiac
anesthesiologists require an in-depth understanding of the steps involved in order to anticipate and mitigate
physiological disturbances during periods of hemodynamic instability [7,24] .

Before surgery, the blood bank should be notified for typing and cross-matching of 6 units of packed red
blood cells, 6 units of fresh frozen plasma, at least 1 or 2 units of platelets (more may be warranted,
depending on initial platelet count and previous antiplatelet medications), and cryoprecipitate. These
products should be available before surgical incision, with the understanding that delays may arise due to
[24]
preexisting antibodies .
Cerebrospinal fluid drainage
Spinal cord injury may be caused by periods of hypoperfusion and subsequent reperfusion injury. The risk
for this devastating complication is high during TAAA and DTA repairs, and preventing it remains a focus
of ongoing research. Placing a CSF drain is an American College of Cardiology, American Heart
Association, and American Association for Thoracic Surgery class I recommendation for any open or
endovascular repair in patients at high risk for spinal cord injury, so long as there is no contraindication to
[25]
placement . A CSF drain allows for careful maintenance of adequate spinal cord perfusion pressure
(SCPP), which is the difference between mean arterial pressure (MAP) and intraspinal pressure (ISP). In
our randomized trial in patients with extent I or II aneurysms, CSF drainage was associated with an 80%
reduction in the incidence of postoperative deficits .
[26]

Practices regarding the timing and location for elective placement of a CSF drain vary across institutions.
Some institutions prefer placement in the preoperative holding area, with the patient sitting and leaning
[27]
forward, similar to the approach used for labor and thoracic epidural placement . Other institutions prefer