Origin of prefabricated frozen elephant trunk

Abstract

At first glance, the frozen elephant trunk (FET) appears as a disruptive innovation in aortic surgery. Like any important surgical innovations, however, be it a product or a procedure, the prefabricated, four-branched device has undergone a stepwise, iterative phase of development prior to its first clinical implantation in 2010. In parallel, the surgical procedure of aortic arch replacement itself has had to mature towards a level of quality and risk control to allow for refinement via a new device. These preparatory technical steps included mastering circulatory arrest, including brain and spinal cord protection, which required decisive innovation in extracorporeal circulation (ECC) management. In addition, patient selection with respect to age and risk factors, but also his or her underlying disease-aneurysm, dissection, atherosclerosis-has been optimized prior to the introduction of the prefabricated substitute for aortic arch replacement. Of utmost importance were those steps, taken by individual surgeons and institutions by use of self-fabricated substitutes, combining various commercially available devices. Thus, the frozen elephant technique, as applied today, did not crash into the armamentarium of unprepared aortic surgeons via device engineering and industrial product development alone. Instead, it resembles an evolutionary process, guided by a number of international institutions exploring preliminary approaches, and learning from each other via scientific exchange. This process, however, would have remained unthinkable without the tremendous advances in medical imaging via tomographic techniques, including their increasing resolution and 3D depiction. This communication will focus on the intermediary surgical steps and the technological advances between the prefabrication of the FET by the medical product industry and its first successful clinical application, as it is used today.

Keywords: Aortic arch surgery; aortic dissection; frozen elephant trunk (FET).

Figure 1

Enabling and facilitating medical technology for the origin of FET. FET, frozen elephant trunk.

Figure 2

Cerebroprotection during aortic arch surgery. (A) ECC circuit allowing for circulatory arrest (upper left) and antegrade cerebral perfusion via open arch vessels (upper right). Lower panel, technique of intracerebral oxygen measurement (left) and its recording (right) during brain perfusion. (B) Our technique of antegrade brain perfusion according to technique of Bachet (12). ECC, extracorporeal circulation; LCA, left coronary artery; RCA, right coronary artery.

Figure 3

Modification and extension in aortic arch repair for aortic dissections, evolving with time.

Figure 4

Hans Georg Borst, inaugurator of the original elephant technique.

Figure 5

Left: the original elephant trunk technique (stage 1); middle: stage 2, completion via open surgical replacement of descending thoracic aorta; right: stage 2, endovascular completion.

Figure 6

Antegrade stenting of the diseased descending thoracic aorta during arch repair. Separate grafts for arch and descending aorta.

Figure 7

Custom-made prefabricated FET for compassionate use in mother institution alone. FET, frozen elephant trunk.

Figure 8

Axial computed tomographic sections of patient three with aneurysms of ascending aorta (A) as well as of proximal descending aorta commencing at origin of left subclavian artery (B). After open surgical replacement of ascending aorta and placement of the stent graft in aortic arch and descending aorta (C), note that of the descending aorta aneurysm has thrombosed completely around graft (D).

Figure 9

Custom-made instrument for deployment of the stented portion of the aortic arch graft int the open descending thoracic aorta at Hannover Medical School.

Figure 10

Early drawing of a collar to facilitate anastomosis of the graft to the proximal descending thoracic aorta, where significant variations in diameter may be present as a result of the underlying disease.

Figure 11

EACTS daily news 2012. Depicted arch grafts: e-Vita left, Hannover Hybrid (customised, middle), Thoraflex (right).

Video

Origin of the prefabricated frozen elephant trunk.