Biomechanical and Elastic Properties of the Ascending Wall of the Human Aorta in Aneurysm

Description of the procedures:

All surgical procedures will be performed via median sternotomy. During the aortic arch anastomosis, continuous, unilateral SACP using innominate artery will be employed. Unilateral SACP may be converted to bilateral ACP at the surgeon's discretion if adequate cerebral flows are not achieved or if there are concerns with cerebral oximetry measurements.

Once on CPB, the patient will be cooled to a nasopharyngeal (NP) temperature of 28-30 °C. Rectal temperature with be monitored as an additional temperature sites. Unilateral SACP will only be initiated once the target temperature has been reached. SACP via the innominate artery will be commenced with target flows of 8-10 ml/kg/min and perfusion pressure of 60-80 mmHg. Perfusion adequacy will be evaluated using measurement of blood pressure in both radial arteries and cerebral oximetry using near-infrared spectroscopy (NIRS).

After completion of the aortic hemiarch replacement, CPB will be resumed and the patient re-warmed to 36 °C prior to coming off CPB, with a = 1 °C temperature difference between temperature monitoring sites (NP and rectal).

Intraoperative information will be collected from the anesthetic record, surgical notes and perfusion records. Intraoperative data collection will include total operative time, CPB time, cross-clamp time, hypothermic cardiac arrest time, uSACP time, lowest nasopharyngeal and rectal temperature, arterial pressure in both radial arteries, perfusion rate and perfusion pressure during both of CPB and unilateral SACP, lowest hemoglobin concentration (g/L) and hematocrit (%), acid-base indices, intraoperative red blood cell transfusion (units), highest dose/agent used for intraoperative inotrope or vasopressor support. Also during the surgery will be performed NIRS and BIS-monitoring.