Gentle cooling of heart during surgery

Cooling Down: Moderate Hypothermia as a Safer Approach to Aortic Dissection Repair

Rhea Morgan in Health & Wellness December 2025 • 4 min read.

"New research suggests that moderate hypothermia may offer a safer alternative to deep hypothermia for patients undergoing surgery for acute type A aortic dissection, potentially reducing the risk of stroke and improving outcomes."

When it comes to complex heart surgeries like repairing a torn aorta (acute type A aortic dissection), protecting the brain is a top priority. For years, surgeons have relied on deep hypothermia (DH), which involves significantly cooling the body to slow down brain activity and reduce its need for oxygen during the procedure.

However, deep hypothermia isn't without its drawbacks. The extensive cooling and rewarming process can be hard on the body, potentially leading to complications like prolonged recovery times and organ dysfunction. That's why some experts have been exploring moderate hypothermia (MH) as a possible alternative.

Now, a new study is adding to the growing evidence that moderate hypothermia might be a smarter choice. The research compares outcomes for patients undergoing aortic dissection repair with either deep or moderate hypothermia, suggesting that the more gentle approach could lead to fewer complications and better survival rates.

Is Moderate Hypothermia Really a Better Option?

The study, published in the International Journal of Angiology, looked back at the records of 132 patients who underwent surgery for acute type A aortic dissection at a single medical center. Of those patients, 105 were cooled using deep hypothermia, while 27 received moderate hypothermia.

The researchers then compared the two groups, focusing on things like:

How well patients recovered after surgery
Whether they experienced major complications
Survival rates over a 10-year period

While the study wasn't a large-scale clinical trial, the results hinted at some potential advantages of moderate hypothermia. For example, the operative mortality rate was lower in the moderate hypothermia group (7.4%) compared to the deep hypothermia group (17.1%). Perhaps even more striking, none of the patients in the moderate hypothermia group experienced a permanent stroke, while 12.4% of those in the deep hypothermia group did.

The Future of Brain Protection During Aortic Surgery

Of course, it's important to remember that this was just one study, and more research is needed to confirm these findings. But the results suggest that moderate hypothermia, possibly combined with techniques to maintain blood flow to the brain during surgery, could be a valuable alternative to deep hypothermia for certain patients. Ultimately, the best approach will depend on the individual patient and the specific circumstances of their case. However, this study offers hope that we can continue to refine our techniques and improve outcomes for people undergoing this life-saving surgery.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1055/s-0038-1675204, Alternate LINK

Title: Role Of Moderate Hypothermia And Antegrade Cerebral Perfusion During Repair Of Type A Aortic Dissection

Subject: Cardiology and Cardiovascular Medicine

Journal: International Journal of Angiology

Publisher: Georg Thieme Verlag KG

Authors: Michael Mchugh, Brian Conway, Marcos Nores, Sotiris Stamou

Published: 2018-10-29

Everything You Need To Know

What is deep hypothermia and why is it used in aortic dissection repair?

Deep hypothermia (DH) is a technique used during complex heart surgeries, like acute type A aortic dissection repair, to protect the brain. It involves significantly cooling the body to slow down brain activity, reducing the brain's need for oxygen. The goal is to minimize potential damage during the procedure when blood flow to the brain might be interrupted. While effective, deep hypothermia can have drawbacks due to the extreme cooling and rewarming process, potentially leading to complications such as prolonged recovery times and organ dysfunction.

Can you explain moderate hypothermia and how it differs from deep hypothermia?

Moderate hypothermia (MH) is an alternative approach to deep hypothermia for brain protection during surgeries like acute type A aortic dissection repair. It involves cooling the body to a lesser extent than deep hypothermia. The potential benefit of moderate hypothermia is that it may reduce the risk of complications associated with the more extreme cooling and rewarming required by deep hypothermia, potentially leading to better patient outcomes.

What is acute type A aortic dissection, and why is brain protection so important during its surgical repair?

Acute type A aortic dissection is a serious condition involving a tear in the wall of the aorta, the body's main artery. Surgical repair is often necessary to prevent life-threatening complications. Protecting the brain during this surgery is critical because the procedure can disrupt blood flow to the brain. Both deep hypothermia and moderate hypothermia are strategies employed to minimize brain damage during these complex operations.

What were the main findings of the study comparing deep hypothermia and moderate hypothermia for aortic dissection repair?

The study compared the outcomes of patients undergoing acute type A aortic dissection repair who were treated with either deep hypothermia or moderate hypothermia. The study suggested that moderate hypothermia may lead to a lower operative mortality rate and a reduced risk of stroke compared to deep hypothermia. However, it is important to note that this was a single-center retrospective study, and more research is needed to confirm these findings.

Besides hypothermia, are there other strategies to protect the brain during aortic dissection surgery?

Maintaining blood flow to the brain during surgery, possibly in combination with moderate hypothermia, is another approach to protect the brain. Ensuring continuous blood flow can help deliver oxygen and nutrients to the brain, minimizing the risk of damage during periods when blood flow might otherwise be compromised. The optimal strategy for brain protection during aortic dissection repair may involve a combination of techniques tailored to the individual patient's needs.