Cardiovascular

Detailed evaluation of the cardiovascular system is essential prior to undertaking complex aortic repair. Major fluid shifts, aortic cross-clamping, and the physiologic stress of intraoperative and postoperative blood loss represent a significant threat to the cardiovascular system. Major thoracic aortic surgery falls into the highest risk group for perioperative cardiac morbidity. Up to two-thirds of patients demonstrate diastolic dysfunction with aortic cross-clamping, and 30% of patients manifest some degree of cardiac dysfunction postoperatively. Hypertension is a common comorbidity, and older patients may also have coexisting coronary artery disease (CAD). Evidence of congestive heart failure may also be present as a result of progressive AI due to aneurysm enlargement.

Cardiac workup should at least include an electrocardiogram (ECG) and TTE, although stress testing and/or coronary angiography are routinely performed at many centers. Patients who are found to have unstable CAD, left main stenosis, or three-vessel disease are typically revascularized prior to or during the repair of the aneurysm. There is debate about whether or not to perform percutaneous coronary intervention (PCI) on less complex lesions because the antiplatelet therapy that accompanies PCI may complicate surgical hemostasis. Occasionally, aneurysmal expansion can result in ischemia from compression of the coronary arteries. Patients taking antihypertensive and antianginal drugs should continue these until the time of surgery, and titrated preoperative anxiolysis medication is important to prevent stress-induced hypertension and tachycardia, which could precipitate aneurysm rupture. Therapeutic anticoagulation or antiplatelet agents should be discontinued or bridged with short-acting alternatives prior to surgical intervention.

Respiratory

The respiratory system also deserves special attention in the preoperative evaluation of patients undergoing thoracic aneurysm repair. Perioperative respiratory failure is the most common serious complication of thoracic and thoracoabdominal aneurysm repair, and patients with a history of smoking or COPD are at especially high risk. Pulmonary function testing and a room air arterial blood gas analysis should be obtained preoperatively because one-lung ventilation (OLV) is important for open surgical repair of Crawford type I, II, III, and V aneurysms. Patients with very poor pulmonary reserve may require cardiopulmonary bypass (CPB) because of an inability to tolerate OLV. Preoperative smoking cessation should be encouraged.

In addition to the evaluation of pulmonary mechanics, history should include consideration of positional dyspnea or stridor, which may indicate aneurysmal compression of the trachea or, more commonly, the left mainstem bronchus. A review of the CT or MRI is important to determine whether significant bronchial compression is present because this may complicate airway management and double-lumen endotracheal tube placement. Finally, patients with significant preoperative respiratory dysfunction should be counseled about the possible need for prolonged postoperative mechanical ventilation, including tracheostomy placement.

Renal

Many patients also have baseline renal insufficiency, which places them at risk for subsequent postoperative renal failure. There is a high incidence of postoperative acute kidney injury following TAAA, with series reporting 1% to 17% of patients requiring hemodialysis and 6% with chronic renal failure. Although evidence for preoperative hydration is minimal, at many centers, it is common practice to admit patients the night before surgery for intravenous (IV) hydration.

Neurologic

The neurologic system deserves special consideration, given the risk to both the brain and spinal cord during aneurysm repair. In an effort to minimize stroke risk, carotid and brachiocephalic angiography are often performed preoperatively, especially in patients with a prior history of stroke or transient ischemic attack. Patients should also be counseled about the risk of possible postoperative paralysis from spinal cord ischemia. Although the risk was historically much higher, the current incidence of postoperative spinal cord injury is between 2% and 15%, depending on the anatomy of the aneurysm, urgency of the repair, patient comorbidities, and surgeon and center experience. Onset can either be immediate or delayed up to 2 weeks, in both open and endovascular repairs.

In summary, preoperative assessment prior to thoracic aneurysm repair is important for both anesthetic and surgical planning. Although aortic surgery represents a high-risk procedure, evaluation of clinical risk factors, multisystem assessment, thoughtful preoperative testing, and, when appropriate, referral to subspecialists for medical optimization can improve perioperative outcome.

References

• Anton JM, Herald KJ. Anesthetic management of open thoracoabdominal aortic aneurysm repair. Int Anesthesiol Clin. 2016;54:76-101.
• Chatterjee S, Casar JG, LeMaire SA, Preventza O, Coselli JS. Perioperative care after thoracoabdominal aortic aneurysm repair: The Baylor College of Medicine experience. Part 1: preoperative considerations. J Thorac Cardiovasc Surg. 2021;161:693-698.
• Isselbacher EM, Preventza O, Hamilton Black J 3rd, et al; Peer Review Committee Members. 2022 ACC/AHA guideline for the diagnosis and management of aortic disease: a report of the American Heart Association/American College of Cardiology Joint Committee on clinical practice guidelines. Circulation. 2022;146:e334-e482.