UPMC Cardiothoracic Experts Identify Optimal Circulatory Arrest Temperature for Hemiarch Replacement with Antegrade Cerebral Perfusion

Circulatory arrest is a technique utilized in aortic surgery where the patient is cooled to a specific temperature that decreases the physiologic metabolism and allows cardiac surgeons to complete aortic surgeries where the blood flow to the body must be briefly discontinued. It was once standard for cardiac surgeons to target 18°C for operations such as hemiarch replacement, but now, in conjunction with antegrade cerebral perfusion, these operations are typically performed at temperatures between 21°C and 28°C. 

Yet the optimal temperature that allows for the safest circulatory arrest using antegrade brain perfusion in elective aortic hemiarch replacement had not been previously identified in practice guidelines. Therefore, UPMC experts led by Danny Chu, MD, professor of Cardiothoracic Surgery, UPMC Heart and Vascular Institute; director, Cardiac Surgery at the VA Pittsburgh Healthcare System, analyzed multicenter data from the Society of Thoracic Surgeons (STS) Adult Cardiac Surgery database to determine the optimal temperature for aortic hemiarch replacement for elective aneurysmal disease using the antegrade brain perfusion technique in the study, “Optimal Circulatory Arrest Temperature for Aortic Hemiarch Replacement with Antegrade Brain Perfusion,” published in The Journal of Thoracic and Cardiovascular Surgery in fall 2021. 

The team primarily investigated early mortality and adverse neurological outcomes. In the paper, researchers including Laura Seese, MD, who served as first author, and Ibrahim Sultan, MD, director, UPMC Center for Thoracic Aortic Disease, found that the lowest risk-adjusted early mortality for this patient population was observed at 27°C, while the risk-adjusted odds of neurological events were similar at all temperatures.

• Patients cooled between 25°C and 28°C had an early survival benefit over those cooled to 24°C. 
• Patients cooled between 21°C and 23°C had the highest risk-adjusted odds of operative mortality. 
• Particularly, researchers observed a 40% increase in the odds of mortality appreciated at 21°C.

Various benefits of cooling patients to warmer temperatures (between 25°C and 28°C) were observed, including fewer hours of mechanical ventilation, lower rates of cardiac arrest, and lower rates of reintubations. Dr. Seese presented these findings at the 2021 American Association of Thoracic Surgeons (AATS) annual meeting. 

“This project was truly a team effort that included experts from the UPMC Center for Thoracic Aortic Disease, the STS, Duke Clinical Research Institute, and many other thoracic aortic surgery specialists across the United States,” Dr. Chu said. “I am hopeful that the results of this study would serve as a practice-changing guideline for thoracic aortic surgeons across the world.” 

Reference

1. Laura Seese, Edward P. Chen, et. al. Optimal Circulatory Arrest Temperature for Aortic Hemiarch Replacement with Antegrade Brain Perfusion. The Journal of Thoracic and Cardiovascular Surgery. 2021.