Conference Coverage

Achieving aortic arch replacement without deep hypothermic circulatory arrest


 

AT AATS AORTIC SYMPOSIUM 2014

References

NEW YORK – A novel technique for aortic arch repair, which avoids both circulatory arrest and profound hypothermia, was associated with low mortality and low cerebral morbidity in a group of 62 patients who underwent aortic arch replacement using this procedure.

Advantages of the "branch-first" procedure include visceral organ and cardiac protection and less need for blood/product transfusions, according to Dr. George Matalanis, who presented the findings at the meeting sponsored by the American Association for Thoracic Surgery.

The branch-first technique avoids many of the pitfalls associated with the widely used combination of antegrade perfusion and deep hypothermic circulatory arrest (DHTA). Such pitfalls include a higher incidence of cerebral injury than with proximal aortic surgery, as well as renal failure, ischemic hepatitis, and paraplegia, said Dr. Matalanis, a cardiothoracic surgeon at Austin Hospital, Kew, Australia. He noted that perfusion cannulas used for antegrade perfusion increase the risk of particulate and air emboli and branch injury or dissection, and their insertion extends cumulative cerebral circulatory arrest time.

DHTA also has a number of clinically significant disadvantages, such as prolongation of cardiopulmonary bypass times during cooling and rewarming, increased potential for cerebral ischemic reperfusion injury, and imposition of time constraints.

A feature of the branch-first technique is that it allows a complete and unhurried repair, allowing the surgeon to systematically interrogate each branch anastomosis, resulting in a low incidence of blood product use. By maintaining cardiac and distal body perfusion, even the most complex reconstructions can be carefully accomplished without concern about incomplete organ protection, allowing complete correction of pathology, according to Dr. Matalanis. The technique avoids the need for deep hypothermia, circulatory arrest, extended periods of cardiopulmonary bypass, and cerebral, cardiac and other organ circulatory exclusion.

Dr. Matalanis presented the results of a study involving 62 patients who underwent arch replacement using the branch-first procedure. The mean age was 65 years, and 60% were men. Almost 40% were urgent/emergent, and 32% had acute type A aortic dissection. One quarter had previous cardiac surgery. This work is an extension of an earlier study, which reported outcomes in 42 patients (Ann. Cardiothorac. Surg. 2013;2:194-201).

There were two deaths (3%), both in patients with acute type A aortic dissection with malperfusion. Neurological events occurred in 5%, with one permanent deficit. Six percent required renal support and 2% intra-aortic balloon support. One-quarter did not need red blood cell transfusion, and 15% did not require red blood cells or platelets/factors. Patients awakened as if they had undergone coronary artery bypass grafting (80% within 48 hours and 25% within 11 hours).

"This technique relies on two basic principles," explained Dr. Matalanis "The first is the extensive collateral network that exists between the three major arch branches, in addition to and far more expansive than the circle of Willis, allowing the brief interruption of one branch to be compensated by collateral flow from the other two. The second is the use of a modified trifurcation graft with a perfusion side arm to reconstruct the arch branches, allowing antegrade perfusion to resume as soon as each branch is reconstructed."

The procedure consists of establishing bypass using femoral inflow and moderate hypothermia (28° C), followed by serial disconnection and reconstruction of each arch branch, proceeding from the innominate to left subclavian, using a trifurcation arch graft with a perfusion side arm port. The proximal descending aorta is clamped, the distal arch anastomosis is constructed, and the aortic root reconstruction is completed. Finally, a connection is made between the common stem of the trifurcation graft and the ascending aorta graft.

There are no periods of global circulatory arrest, no interruption to cerebral perfusion during the anastomosis of the two grafts, and cardiac perfusion is maintained during the whole phase of arch branch reconstruction. Distal organ perfusion is also maintained throughout the procedure, says Dr. Matalanis.

Disadvantages of the branch-first technique include loss of the deep hypothermia "security blanket," the possibility of clamp injuries or air/thrombo-embolism, and difficulties with femoral cannulation. Issues may also arise with kinking or stenosis of the trifurcation graft and adhesions.

Dr. Matalanis reported having no relevant financial disclosures.

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