Total arch replacement: technique of separate reimplantation of epiaortic vessels

Operative approach
The operation is usually performed through a median sternotomy, with extensions of the incision to both supraclavicular regions. This approach allows us to reach the descending aorta up to 5 cm distal to the origin of the left subclavian artery.

If the aneurysm is large enough in size, the descending aorta at the level of the tracheal bifurcation (T6) can be reached.

Cardiopulmonary bypass 
Cardiopulmonary bypass (CPB) is established by cannulating the ascending aorta or the right axillary artery, when necessary, for arterial inflow, and the right atrium, using a single two-stage cannula for venous drainage. After SCP is established, the left ventricular vent is inserted through the right superior pulmonary vein. Myocardial protection is provided by both antegrade and retrograde blood cardioplegia.

Epiaortic echo scanning and transesophageal echocardiography are routinely performed to select the site of arterial cannulation. If the ascending aorta is free from atherosclerotic debris, it is the preferred site for arterial cannulation. If the ascending aorta is found to be inappropriate because of the presence of atherosclerotic debris, the alternative site for arterial cannulation is the right axillary artery. An 8-mm Dacron graft is sutured to this artery in an end-to-side fashion.

Selective cerebral perfusion cannula
For antegrade SCP, a newly developed flexible perfusion cannula (Fuji System Corporation, Tokyo, Japan) is used (Photo 1). This cannula has 3 lumina: one for blood perfusion, one for balloon inflation, and one for pressure monitoring. A balloon at the tip prevents slippage of the cannula when inflated after cannulation of the arch vessels. The cannula, because of its flexible metallic support, can be bent manually at the desired angle without causing any luminal compromise.

This property of the cannula allows the surgeon to place it toward the patient’s head so that it does  not obscure the operative field. Cannula sizes used are 18 F for innominate artery perfusion and 14 F for left common carotid artery perfusion.

Antegrade selective cerebral perfusion protocol 
In principle, the bilateral 2-arch vessel perfusion technique is used (Schematic 1) [8, 9].

Both innominate and left common carotid arteries are perfused at a rate of 10 ml/kg/min at a rectal temperature of 25° C by a single pump separate from the systemic circulation. The left subclavian artery is kept cross-clamped during SCP. The right radial arterial pressure as well as the bilateral catheter tip pressure are adjusted to around 40 mmHg to regulate the perfusion pressure. Arterial blood pH is managed according to the alpha-stat strategy during CPB.

If the right axillary artery is used for arterial cannulation, systemic perfusion is started through the graft sutured to this artery together with the femoral artery. After cooling the patient, the innominate artery is clamped proximally, the left common carotid artery is cannulated, and both right axillary and left common carotid arteries are perfused as SCP (Schematic 2).

Three-arch-vessel perfusion (Schematic 3), that is additional left subclavian artery perfusion, is performed in selected patients who have occlusion of right vertebral artery, dominant left vertebral artery, and lack of efficient intracranial arterial communication, to avoid the risk of vertebrobasilar artery insufficiency.

Four-branched aortic arch grafts
Four-branched aortic arch grafts used for the separated graft technique are commercially available (Photo 2). Three branches are used for arch-vessel reimplantation, and one is used for antegrade systemic perfusion after the distal graft anastomosis is complete.

Separated graft technique
Schematic 4 shows the separated graft technique, which is now our preferred surgical procedure [10, 11].

Under SCP with systemic circulatory arrest, the distal end of the arch graft is sutured to the descending aortic stump. Antegrade perfusion is started from the side branch of the graft. The left subclavian artery is sutured to the 3rd branch of the arch graft and rewarming by CPB is begun. The proximal end of the arch graft is sutured to the ascending aortic stump. 

Then the innominate and the left common carotid arteries are sutured to the corresponding branches of the arch graft. An MR angiogram (Photo 3) shows the completed reconstruction. The details of the operative procedure are shown in Videos 1–17.

Separated graft technique for acute type-A dissection
The separated graft technique is also safely used in patients with acute type-A dissection [12]. The surgical technique is essentially similar to that used in an atherosclerotic aneurysm except for the obliteration of the proximal and distal false lumen and the elephant trunk technique, in which a short segment of graft is placed in the true lumen of the descending aorta (Schematic 5).

Advantages of separated graft technique 
The separated graft technique presents several advantages over the en bloc technique or island technique, in which the arch vessels are reimplanted to the side hole of the graft (Schematic 6) [13].

These advantages include:
1. Arch vessel anastomoses are performed at the intact distal arteries where they are free from atherosclerotic debris or dissection.
2. The pathological portion of the aortic arch can be completely resected in a Marfan’s patient.
3. Bleeding from the site of the arch vessels anastomoses can be easily controlled.
4. Antegrade systemic perfusion through the arch graft prevents retrograde embolization or organ malperfusion.