New clues to high blood pressure after aortic dissection

Published: 29 September 2026

Researchers are investigating whether the body’s fight-or-flight response drives dangerous blood pressure spikes after aortic dissection.

New research into one of the most life-threatening cardiovascular emergencies, aortic dissection, is looking at why survivors often have dangerously high blood pressure long after the event and whether new targeted treatments could reduce the risk of future events.

An aortic dissection is one of the most serious medical emergencies affecting the heart and blood vessels. It occurs when a tear develops in the wall of the aorta, the body's main artery.

The condition can rapidly become life-threatening, and many people die before reaching hospital. Even with emergency treatment, aortic dissection carries a significant risk of death, particularly in the first days and weeks after it occurs.

Dr Ryan Sixtus, from the University of Auckland, has received a Heart Foundation research fellowship to investigate why many aortic dissection survivors experience dangerously high blood pressure despite treatment.

Ryan believes the nervous system may be part of both the problem and the solution.

Ryan is part of a University of Auckland collaboration led by cardiothoracic surgeon and Heart Foundation F100 Fellow Associate Professor Nishith Patel and Professor James Fisher. The team will investigate whether an overactive sympathetic nervous system, the body's 'fight-or-flight' response, is linked to sudden blood pressure surges after aortic dissection.

"When the sympathetic nervous system is activated, it acts as the body's accelerator," he says. "For a lot of survivors and people with high blood pressure, this accelerator is jammed on."

High blood pressure is the most common risk factor for aortic dissection and a major influence on how long survivors live. When blood pressure remains high, it places ongoing strain on the weakened aorta and raises the risk of another tear or rupture.

For people who survive, controlling blood pressure is a lifelong priority. However, many survivors have resistant hypertension, which means their blood pressure stays high despite taking several medicines.

"The aortic dissection community told us at the annual Aortic Dissection Awareness Day that one of the biggest challenges they face is controlling their blood pressure. They don't want to be dying from further complications. They want to be able to live their lives without fear," he says.

"These are people who are doing everything right, taking multiple tablets a day, yet their blood pressure still won't budge. That tells us we might not be correctly targeting the real underlying problem."

Understanding the root cause

The researchers will directly measure sympathetic nerve activity in aortic dissection survivors and assess how it affects blood pressure control, arterial health and responses to everyday situations such as exercise, cold temperatures and mental stress.

"We want to change the way this condition is treated. Current medicines target things such as blood volume, the kidneys and heart rate. What we're saying is they might not be targeting the right thing," Ryan says.

"What we need to do first is show that the accelerator is on and not coming unstuck. If that's proven, it could offer a new direction that allows us to more effectively control blood pressure by targeting or dampening down the fight-or-flight response."

Looking for earlier warning signs

The study will also include people with aortic aneurysms, who have a greater risk of aortic dissection. By comparing them with people who have survived aortic dissection, the team hopes to find out whether overactive sympathetic nerve activity and extreme increases in blood pressure could help identify people at increased risk of a future dissection.

Ryan says controlling blood pressure is about much more than preventing another aortic dissection.

"Maintaining healthy blood pressure reduces the risk of another event. It doesn't have to be another rupture or dissection we're preventing. It could be a heart attack, a stroke or any number of cardiovascular problems."

He compares it to maintaining an ageing vehicle.

"It's like having a beat-up old car. You might fix one broken hose, but if you don't deal with the underlying issues, something else will eventually go wrong. We can repair an aorta, but if we don't tackle the high blood pressure that's damaging the system, we're constantly patching problems without fixing the underlying cause."

The goal is to prevent future aortic dissections and improve survivors' cardiovascular health and quality of life.

Heart Foundation Medical Director, Dr Gerry Devlin, says Ryan and his colleagues' research offer hope to people who have survived, or who are at risk of, aortic dissection.

"For people living with aortic disease, survival is only the first step," Gerry says.

"This research could help us better understand why blood pressure remains difficult to control and lead the way for more tailored care that reduces future complications and helps people live longer, healthier lives."