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Originally published April 25, 2025
Last updated April 25, 2025
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A type A aortic dissection, located in the ascending aorta, is an immediate medical and surgical emergency. It can also, however, lead to complications and adverse events in the future that may require further interventions. Even after open-heart surgery is performed to repair a type A aortic dissection, for instance, patients whose aortic arch or descending aorta are dissected or aneurysmal face the risk of a future aortic rupture or worsening dissection.
“If you have an aorta that is already very wide and aneurysmal, the risk of it rupturing in the future becomes high,” says Serge S. Kobsa, MD, PhD, a cardiac surgeon with Keck Medicine of USC. Kobsa is associate director of the USC Comprehensive Aortic Center, part of the USC Cardiac and Vascular Institute at Keck Medicine.
Each year, Kobsa and his colleagues treat many type A aortic dissections. In some of these patients, a total aortic arch replacement — specifically, a zone 2 total aortic arch replacement with a frozen elephant trunk — is a prescient treatment in the long term. As Kobsa explains, although a total arch replacement is extensive and complex, it can save patients who need aortic repairs down the road the need to undergo another open-chest surgery.
It is thought that some type A aortic dissections may require total arch repair; however, proper patient selection for this extensive and complex operation is a matter of some controversy and active research. “A type A aortic dissection typically originates and, by definition, involves the ascending aorta. In a vast majority of cases, that dissection extends from the ascending aorta into the aortic arch and, very commonly, into the descending aorta as well — a so-called DeBakey type I dissection,” Kobsa explains. “And it can go all the way down into the abdominal aorta and down to the femoral vessels. It can often also involve the head vessels, the major vessels that come off of the aortic arch: the innominate artery, the left common carotid artery and the left subclavian artery.”
Depending on specific findings, if a patient’s acute type A aortic dissection involves the aortic arch, the head vessels or the descending aorta, Kobsa says a total arch repair is often beneficial. “This,” he explains, “essentially involves replacing a better part of the aorta in the chest, typically the ascending aorta and the aortic arch, with an artificial graft material.”
The procedure Kobsa and his colleagues at the USC Comprehensive Aortic Center often use is a zone 2 total aortic arch replacement with a frozen elephant trunk. This procedure replaces the entire aortic arch in the zone 2 area between the left common carotid artery and the left subclavian artery. Once this is done, Kobsa and his colleagues then place an endovascular stent-graft in the thoracic descending aorta using the frozen elephant trunk procedure (also known as open-stent grafting). The frozen elephant trunk procedure is an improvement over the conventional elephant trunk procedure because it simultaneously replaces the aortic arch and stents the descending aorta, stabilizing the aorta in one procedure.
Importantly, the frozen elephant trunk procedure also improves the chances that future aortic repairs, if needed, can be done endovascularly.
“Total arch replacement with a frozen elephant trunk addresses the entirety of the aorta that is dissected in the central portion of the chest,” Kobsa says, “but, more importantly, it creates landing zones for potential future interventions using endovascular techniques. To use an endovascular stent to repair the aorta, you must have a portion of the aorta that is structurally sound so that these stents can anchor in those areas and create a seal — a so-called ‘landing zone.’ If we leave any of the dissected or dilated portion of the aorta remaining during a type A dissection repair, then that portion of the aorta cannot really serve as a landing zone in the future as a structural basis for endovascular stents because it will not seal or will risk rupturing.”
Without this type of extensive repair up front during the initial operation, patients needing aortic repair for an aortic rupture or dissection in the future would likely have to undergo another open-chest surgery — a reoperative total arch replacement — to replace the aneurysmal aorta.
“For patients who have a residual dissection in their descending aorta after a type A dissection that needs to be repaired, if the aorta was not repaired in the manner described above — if the total arch replacement was not done at the time of the original type A dissection — then those patients very often have to go back and have another, reoperative open-chest surgery in order to replace the arch and then potentially later receive the endovascular interventions,” Kobsa says.
It’s also worth noting that for total aortic arch replacement, Kobsa and his colleagues advocate a branch-first technique in which the initial portions of the head vessels are replaced before replacing the aortic arch. This method was shown in retrospective research published by USC Cardiac and Vascular Institute cardiothoracic surgeon Fernando Fleischman, MD, to significantly lower 30-day mortality compared with traditional total arch replacement techniques. The coauthors of this journal article, including some of Kobsa’s Keck Medicine colleagues, stated, “Branch-first [total aortic arch replacement] has been described as an alternative approach to traditional techniques and typically proceeds with serial clamping, debranching, and reperfusion of the head vessels using a trifurcated graft with a side perfusion port.”
Kobsa says preemptively employing total aortic arch replacement with a frozen elephant trunk may yield better long-term options for many type A aortic dissection patients, but whether this is true across the board will need to be investigated in future research studies. Additionally, however, performing this procedure requires a lot of experience in aortic arch surgery. At the USC Comprehensive Aortic Center, surgeons, OR staff, ICU teams and anesthesiologists have that experience, he says.
“We are well equipped to do these operations, which are far more extensive than what I would describe as a standard approach to repairing type A dissection, which is typically called a hemiarch operation,” he says. “Surgeons and institutions that don’t have extensive experience in aortic arch surgery are certainly not in a good position to try to do these complex operations, especially in a very acute, emergent setting like a type A dissection.”
Deciding if a total aortic arch replacement with a frozen elephant trunk should be performed depends on the size of a patient’s aortic arch and descending aorta. “If there is an aneurysm of the aortic arch of the descending aorta, in addition to the dissection that is there, then certainly this approach is warranted,” Kobsa says.
Another use case is if the entry tear (the actual tear in the dissection flap) extends into the aortic arch or the descending aorta, he says. Finally, he says, “If there is a bad dissection extending into the head vessels, I think select patients can also benefit from this more extensive repair.”
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