Download Axillary Cannulation in Cardiopulmonary Bypass for Thoracic Aorta

Yvon Raoul Baribeau, M.D.; Benjamin Minge Westbrook, M.D.
· INTRODUCTION.
The need for an extraaortic cannulation site occurs
regularly in cardiac surgery, and although the femoral
artery has been used most frequently, it has been frowned
with complications including thrombosis, tear, local and
dreadful proximal dissection (1-3) and possibly increased
stroke rate by retrograde flow (4). The axillary artery
has been used frequently in peripheral revascularization
since the first description of the axillofemoral bypass by
Blaisdell in 1963 (5). Vascular surgeons were already
exploiting the lesser incidence of atherosclerotic
involvement of the axillary artery and upper limb vessels
compared to the femoral and tibial vessels (6). Despite
wider use as an outflow source, there has been only
anecdotal use of the axillary artery as an inflow vessel
until Sabick report on direct axillary cannulation in thirtyfive patients (7). There was a 5.7% incidence of
neurovascular injury. Bichell reported seven patients with
axilloaxillary bypass with direct cannulation without
neurovascular injury (8). We also described our technique
by graft interposition on the medial first part of the
axillary artery with no neurovascular complications in
twenty-nine patients (9).
· ANATOMY OF THE AXILLARY ARTERY.
The axillary artery is a continuation of the subclavian
artery as it leaves the superior border of the first rib,
and terminates at the lower border of the teres major
(10). It is divided in three parts by the pectoralis minor.
The first part is proximal to the last muscle and the only
branch given is the supreme thoracic which supplies
the first intercostal space and the pectoralis major and
minor muscles. More importantly, none of the brachial
plexus cords has reached the artery, and only the posterior cord lies posterior to the artery. The lateral pectoral
nerve crosses anteriorly to the artery on its way to
innervate the pectoralis major muscle (11). It forms a
loop in front of the artery by sending a ramus to the
medial pectoral nerve. Both also supply the pectoralis
minor muscle. The second part is lying behind the
pectoralis minor and becomes surrounded by the three
cords of the brachial plexus, lateral, medial and posterior. It gives off two branches: thoracoacromial and lateral thoracic. The third and last portion of the axillary
lies lateral to the pectoralis minor to the lower border of
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the teres major muscle. The artery is also surrounded by
the secondary branches of the brachial plexus and gives
three branches: subscapular, posterior and anterior
humeral circumflex branches.
Because of this anatomical position, the first portion
is the only one without brachial plexus involvement, and
this has been our preferred site of graft anastomosis for
cannulation of the axillary artery (9). Indeed, Blaisdell
(5) targeted the same portion in his first description of
the axillofemoral bypass.
· PATIENT SELECTION AND ANESTHESIA.
All our surgical patients are screened preoperatively
with bilateral brachial pressure measurement. Significant
gradient is defined as a difference greater than 15 mm
Hg. Most of these patients will have an arch arteriogram
to define any proximal arch branch stenosis, and the
operation is performed accordingly. Any proximal
stenosis to the right (preferred) axillary artery is a
contraindication to the axillary technique. As well, most
patients have a carotid duplex examination preoperatively.
Particular attention is given to occlusion of one or two
carotids in view of the double incidence of severely
atherosclerotic proximal aorta in these patients (12), and
need for extraaortic cannulation then if off-bypass is
not an option. Pressure monitoring is realized with two
Figure 1: Subclavicular incision, dissecting medial to the
pectoralis minor.
AXILLARY CANNULATION IN CARDIOPULMONARY BYPASS FOR THORACIC AORTA REPAIR
radial lines since the systemic pressure on bypass will
be read from the left (contralateral) side. The ipsilateral
right radial line will be higher reflecting the increased ar
flow from the graft interposition technique of cannulation.
We favor the graft interposition technique to allow
easy control on the artery from the arteriotomy time to
closure. An horizontal incision is made below the medial
third of the right clavicle (fig. 1), or on the left if the
right cannot be used. The clavipectoral fascia is incised
and pectoralis major fibers retracted to expose the axillary
vein. The pectoralis minor if seen is retracted laterally.
The axillary artery is easily exposed under the vein and
gently mobilized for 2 centimeters. An umbilical tape is
looped around the artery, and gentle traction applied.
After heparinization a side-bite clamp is then applied
across the artery clamping the artery proximally and
distally at the same time, and an 8 mm woven Dacron
graft (Meadox Medicals, Inc. Oakland, New Jersey) or
8 mm Gelweave graft (Sulzer Vascutek USA, Austin,
Texas) is anastomosed with Prolene 4-0 or 5-0 depending
on the size of the artery (fig. 2). The graft is then
clamped and the side-bite clamp released. Any
anastomotic bleeding is corrected then. Next it is
connected to a 24 French “arch” or Flexible Arterial
Cannula (Sarns 3M Health Care Ann Harbor Michigan)
and the pressure compared to the contralateral radial
systemic pressure to confirm that there is no gradient.
Venous inflow is obtained through right atrial cannulation
after sternotomy or through the femoral vein
percutaneously using a Bio-Medicus cannula (Medtronic
Bio-Medicus, Inc, Eden Prairie, Minnesota) with
vacuum assist. Extracorporeal circulation is then
established at 2.2 to 2.8 l/m2/min at normothermia
(fig. 3). During extracorporeal circulation the systemic
pressure is monitored through the contralateral radial
line since pressure tends to be higher on the side of the
perfused axillary artery.
If circulatory arrest is necessitated, the patient is cooled
down to 22° C and the innominate artery clamped while
the flow is simply turned down at the desired level, usually
10 cc/kg/min. Our flow rate during circulatory arrest is
based on normal physiology (13) and the studies by Tanaka
and colleagues at moderate hypothermia (14). Based on
experimental and clinical datas, they recommend a
perfusion rate of 10 ml/kg/min at a pressure greater than
30 mm Hg or more for selective cerebral perfusion. The
left common carotid can be clamped as well if no
significant disease exists at the proximal segment (fig.
4). The brain perfusion pressure is monitored through
the right radial artery during that time and kept at or below
50 mmHg. When extracorporeal circulation is reestablished, the proximal innominate artery is released and
the flow simply increased to 2.2 to 2.4 L/m/min and the
patient rewarmed (fig. 5). At the end of the procedure,
Figure 2: End to side anastomosis is created using an 8 mm
Hemashied (Meadox Medicals, Oakland NJ) or Gelweave
(Sulzer Vascutek,Austin TX) graft, then connected to a 24F
flexible “arch” cannula (Sarns 3M, Ann Harbor MI).
Figure 3: Antegrade extracorporeal circulation is established.
Systemic pressure is monitored through contralateral left
radial line.
· TECHNIQUE OF CANNULATION.
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