Both the proximal and distal aortic stumps have to be stabilized with a felt strip and biological glue in all cases. In addition, the distal anastomosis has to be created openly in all cases. Today, the subclavian artery is cannulated in most cases so that cerebral perfusion can be carried out during the procedure on the aortic arch, or while creating the open anastomosis in the area of the distal ascending aorta. If aortic arch replacement is necessary, the supra-aortic branches can be excised as a common island in most cases and reimplanted into the prosthesis later. If the dissection is to include the supra-aortic branches as well, aortic arch prostheses are available nowadays with prefabricated separate Dacron prostheses emerging from the prosthesis for the brachiocephalic trunk, the left common carotid artery, and the subclavian artery.
Another special form of aortic arch replacement is the “elephant trunk” technique. This is discussed with aortic arch surgery below.
Fig. 2.1–9a-e Surgical steps in acute aortic dissection.
In acute dissections, particular attention should be given to the aortic root. Using biological glues and felt strips, it is often possible to carry out supracoronary ascending aorta replacement. However, if the dissection already includes the coronary ostia or has completely destroyed the aortic root, a David operation should be considered as well, possibly in combination with bypass treatment for dissected coronary arteries.
Fig. 2.1–10a, b Hemi-arch replacement with isolated valve replacement.
Conventional aortic arch replacement
Hemi-arch replacement
Hemi-arch replacement means replacement of the concave part of the aortic arch using an open anastomosis technique. This often-used procedure not only allows complete replacement of the ascending aorta, but also specialized arch replacement without the need to reimplant the supra-aortic branches. This surgical procedure can be used for both degenerative aneurysms and dissections (Fig. 2.1-10).
Replacement of the complete aortic arch
Replacement of the complete aortic arch is now carried out in combination with antegrade cerebral perfusion (usually via the right subclavian artery) (Fig. 2.1-11). Replacement of the entire aortic arch can be carried out:
Operations in the area of the aortic arch with antegrade cerebral perfusion are carried out with the patient in hypothermia (bladder temperature 22–25°C). During antegrade cerebral perfusion via the right subclavian artery, the brachiocephalic trunk, left carotid artery, and left subclavian artery are either clamped, closed with rubber bands, or blocked with catheters to prevent reverse bleeding from these vessels, resulting in a potential cerebral steal phenomenon, and to improve visibility in the surgical field. In most cases, a presealed Dacron tube prosthesis 24–30 mm in size is used as a substitute aortic arch, and the anastomoses are created with felt reinforcement. In the first step of the operation, the anastomosis to the descending aorta is carried out, and the island of the supra-aortic branches is then reimplanted into the prosthesis. Initially, a felt cuff is anastomosed onto the aortic stump using 4–0 Prolene with a mattress technique, to provide better quality in the aorta for later anastomoses. After exhaustive elimination of air, perfusion of the whole brain and lower half of the body is restored via the brachiocephalic trunk.
The proximal aortic anastomosis is carried out as the last step in the operation, either in a supracoronary position or as an anastomosis between two prostheses.
Protecting the myocardium is particularly important in these very large and often prolonged operations. The authors exclusively use cold antegrade/retrograde blood cardioplegia with terminal warm reperfusion. In addition, the surgical field is flooded with CO2. The patient is warmed to a bladder temperature of 35°C. Subsequent stepwise warming up to 36–37°C is then carried out later in the intensive care unit with the appropriate warming mats.
Elephant trunk technique
Fig. 2.1–11a-e Replacement of the aortic arch with a distal end-to-end anastomosis and reimplantation of the supra-aortic branches in an island.
Fig. 2.1–12a, b Complete arch replacement with separate prosthetic use of the brachiocephalic trunk, left common carotid artery and left subclavian artery.
Patients with aortic aneurysms extending from the aortic root over the ascending aorta and the entire aortic arch to the descending aorta represent a special problem. To minimize the problems in these large operations, Borst and colleagues (Borst et al. 1983, 1988) developed a two-step surgical technique in which the ascending aorta and aortic arch are initially replaced, with a segment of a distal Dacron graft being introduced into the descending aorta. The method is known as the “elephant trunk” technique. Numerous modifications of the original technique now exist, such as that described by Svensson and Crawford (1997) (Fig. 2.1-13a-r).
Frozen elephant trunk technique
Another method of replacing the aortic arch and descending aorta via a median sternotomy involves a combined endovascular stent graft implantation with conventional aortic arch replacement (a hybrid technique). This technique was first described by Suto and colleagues (1996) and Usui and colleagues (1999). It was later named the “frozen elephant trunk” technique (Karck et al. 2003, 2005, 2008). In this technique, the entire aortic arch is first dissected free and opened. A special stented Dacron prosthesis with a Dacron prosthesis at its cranial end is then introduced via the aortic arch into the descending aorta. After previous measurement of the diameter of both the distal and proximal landing zones in the area of the descending aorta and of the desired length of the stent, the prosthesis can be implanted via the aortic arch under direct vision. The Dacron prosthesis attached to this Dacron-coated stent is then retracted and used to replace the aortic arch.
Replacement