Mechano-biology in the thoracic aortic aneurysm: a review and case study.

An aortic aneurysm is a permanent and localized dilatation of the aorta resulting from an irreversible loss of structural integrity of the aortic wall. The infrarenal segment of the abdominal aorta is the most common site of aneurysms; however, they are also common in the ascending and descending thoracic aorta. Many cases remain undetected because thoracic aortic aneurysms (TAAs) are usually asymptomatic until complications such as aortic dissection or rupture occurs. Clinical estimates of rupture potential and dissection risk, and thus interventional planning for TAAs, are currently based primarily on the maximum diameter and growth rate. The growth rate is calculated from maximum diameter measurements at two subsequent time points; however, this measure cannot reflect the complex changes of vessel wall morphology and local areas of weakening that underline the strong regional heterogeneity of TAA. Due to the high risks associated with both open and endovascular repair, an intervention is only justified if the risk for aortic rupture or dissection exceeds the interventional risks. Consequently, TAAs clinical management remains a challenge, and new methods are needed to better identify patients for elective repair. We reviewed the pathophysiology of TAAs and the role of mechanical stresses and mathematical growth models in TAA management; as a proof of concept, we applied a multiscale biomechanical analysis to a case study of TAA.

Successful reversal of recurrent spinal cord ischemia following endovascular repair of a descending thoracic aortic aneurysm.

Despite recent advances in technique, spinal cord ischemia remains one of the most dreaded complications of thoracic aortic surgery. Recently, it has been suggested that thoracic endovascular aortic repair may decrease the risk of paraplegia. We present a case of delayed paraplegia following thoracic endovascular aortic repair that was successfully reversed on 3 separate occasions in the same patient. This highlights the importance of vigilant clinical assessments, efficient multidisciplinary teamwork, and maintenance of the determinants of spinal cord perfusion following endovascular thoracic aortic intervention.

Anesthesia for deep hypothermic circulatory arrest in adults: experience with the first 50 patients.

OBJECTIVE: To evaluate the efficacy of a simple method of central nervous system (CNS) protection in patients undergoing deep hypothermic circulatory arrest (DHCA) lasting less than 30 minutes, for a variety of complex cardiovascular procedures. DESIGN: A retrospective case review. SETTING: A university teaching hospital. PARTICIPANTS: Fifty consecutive patients (25 women, 25 men) undergoing elective or emergency cardiovascular operations requiring DHCA between August 1991 and December 1996. INTERVENTIONS: Patients underwent DHCA for a variety of surgical procedures. Neurologic protection was with thiopental, ice packs to the head, and systemic core hypothermia to a nasopharyngeal temperature (NPT) of 18 degrees to 20 degrees C. MEASUREMENTS AND MAIN RESULTS: The mean duration of circulatory arrest was 18 +/- 10 minutes (range, 5 to 42 minutes). The mean NPT at time of arrest was 18.7 degrees +/- 1.7 degrees C. Three patients (6%) had gross CNS morbidity, one of whom died. The circulatory arrest times for these three patients were 8, 39, and 40 minutes. Perioperative mortality was 8% (n = 4). The circulatory arrest times for the patients who died were 12, 13, 23, and 39 minutes. CONCLUSION: The anesthetic management of DHCA described is simple, effective, and safe, and can be performed in any institution that performs cardiac surgery.