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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3734_Библиотеки_им_академика_М_И_Перельмана
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326
* SeeBSFr Decision Tree
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Changing Dissection
Treatment Paradigm
Acute Type A Dissection
Exceptionally
High Risk?
YES
NO
E. Germano et al.
Recently Active +
Good Anatomy
ASG+/- Additional
Stenting
Unfit for Op
or Endo
OMTx, Hospice
DeBakey
1
B-SAFER+/-
Root*
Limited Prox
Repair +/- Root
DeBakey
2
Limited Prox
Repair +/- Root
Fig. 2 The current decision-making algorithm for acute ascending aortic dissection at the
Cleveland Clinic. Op operation, Endo endovascular, ASG ascending stentgraft, OMTx optimal
medical treatment, B-SAFER branch stented anastomosis frozen elephant trunk repair, Prox
proximal
graft material infolding at the level of the anastamosis. The frozen elephant trunk
device main aortic stent graft is usually 10 or 15cm long, depending on the shape
of the arch so that it can extend beyond the curve of the arch and land parallel into
the upper descending aorta. The use of devices longer than 15cm may increase risk
for spinal cord injury and should be avoided. If the arch branch vessel stenting is
also planned, these devices are also selected preoperatively based on detailed imaging analysis of target vessels [25].
Our preferred technique for repair in the patient who is hemodynamically stable
on presentation begins with cutdown and exposure of the right axillary artery and
end-to-side anastomosis of an 8 or 10mm side graft on the axillary artery [26].
Median sternotomy and standard two-stage venous cannulation are then employed.
For patients who undergo this technique, right radial or brachial arterial access is
mandatory to monitor brain perfusion pressure during selective antegrade brain perfusion (SABP). A second arterial line in the contralateral arm or either femoral
artery is also helpful in determining accurate systemic perfusion pressures.
Cardiopulmonary bypass is then initiated via the axillary artery and cooling is begun.
In the hemodynamically unstable patient who presents in extremis, we forego
axillary artery cannulation and initiate cardiopulmonary bypass as expeditiously as
possible. Our preferred technique in this instance is emergency median sternotomy
to relieve tamponade followed by central aortic cannulation utilizing modied
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Seldinger technique with echocardiographic guidance to ensure the cannula is in the
true lumen of the aorta. As we have gained more experience with this technique, we
have increasingly been using it in stable patients as well to save time [27].
Once cardiopulmonary bypass is initiated and as the patient is being cooled,
exposure of the distal ascending and aortic arch is obtained. The innominate vein is
dissected free and retracted cranially using a self-retaining retractor. The remainder
of the arch is dissected via takedown of the pericardial reection and dissection of
the head vessels, which are then encircled with vessel loops. When the patient has
been cooled to a goal nasopharyngeal temperature of <24°C and bladder temperature of <28°C with electrical silence on bispectral index monitoring, the heart is
arrested, the innominate and left common carotid arteries are clamped and selective
antegrade brain perfusion (SABP) is initiated. We typically run the SABP perfusate
at a rate of ~1L/min and a perfusate temperature of <18°C.
The aorta is then transected obliquely from the base of the innominate artery to
the underside of the aortic arch. The stent is then brought into the eld, precurved,
and delivered in an antegrade fashion down the descending aorta. Use of Intravascular
Ultrasound (IVUS) to help guide wire placement prior to device delivery can assist
with safe access of the stent graft into the true lumen. After deployment, the stent
graft is secured to the lesser curve of the aortic arch with a 4-0 polypropylene suture.
Fine adjustment to the position of the device can be made before suturing into place.
It is usually positioned such that it covers the left subclavian artery ostia and depending upon the location of entry tear, it may also cover the origin of left common
carotid artery. Fenestrations in the device are cut with a scalpel at the location of
covered arch branch arteries. Short branch stent grafts (typically 2–3cm in length)
are selected so as to minimize branch vessel manipulation. The branch stent grafts
are directly positioned through these fenestrations over a wire into the target vessels
and deployed. Proper positioning of branch stent is conrmed by direct visualization and the devices are expanded by direct manipulation with a clamp and gently
molded with a soft conformable occlusion balloon. The branch devices are aligned
with about 5–10mm of extension into the aortic lumen to assure good overlap and
xation. This rst suture line is then run circumferentially to the stentgraft and the
aortic wall and typically runs around the distal edge of the left common carotid
(zone 2) or innominate artery (zone 1) to optimize xation and seal in the arch.
The surgical graft to replace the ascending aorta and hemiarch is sized based on
the diameter of the sinutubular junction. The graft is beveled distally and then
sutured circumferentially to the transected aorta and the stentgraft and along the
proximal edge of the innominate artery. In patients with particularly complex branch
anatomy, or a large aneurysm of the arch itself, the innominate or left common
carotid arteries may be separated from the aorta and reconstructed as separate anastomoses. This multiple anastamotic variation of the B-SAFER operation is typically
reserved for chronic dissection cases (Fig.3).
Following anastomotic completion, the entire graft is deaired and clamped proximally. Full cardiopulmonary bypass is then re-initiated and warming commenced.
During re-warming, attention is turned to the aortic root. Next the attention is
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Fig. 3 Illustration of the
multiple anastomoses,
single stent B-SAFER
operation
E. Germano et al.
directed to the proximal aortic reconstruction based on the condition of the aortic
root. Mostly, the valve and root can be preserved by re-approximation of the dissected layers at the level just above the coronary ostia. Other options included valve
replacement with a bioprosthesis and supracoronary graft anastomosis, total root
replacement with reimplantation of the coronaries and valve replacement (modied
Bentall), or valve sparing root replacement (modied David’s procedure in young
stable patients).
In case of concern that the patient may have ongoing distal malperfusion, aortography or intravascular ultrasound may be performed. Based on the ndings
additional endovascular interventions can be extended distally [28]. This may
include the addition of a bare aortic dissections stent (Zenith dissection device,
Cook, Indiana, USA) directed at dynamic compression or additional branch vessel stenting directed at treating focal static branch occlusion. These adjunctive
procedures can best be performed in a timely manner in the hybrid operating room.
Postoperative care for the patient with the frozen elephant trunk repair is the
same as any other patient who presents with acute type A dissection. Patients are
imaged with contrast-enhanced CT angiography prior to discharge, 3 months postoperatively, and annually.
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Results
Several reports have been published from Europe and Asia where frozen elephant
trunk devices have been commercially available for several years. Outcomes for
these procedures in most of the experiences have been similar to what is expected
with conventional approaches [29, 30]. In a recent combined series from two of the
busiest centers in Europe the mortality was 14.9%, stroke rate was 10.8%, and spinal cord injury was 5.5% [31].
One of the biggest concerns with the early reports on the frozen elephant trunk
repair has related to the potential for increased risk of spinal cord injury, a complication not typically seen with limited repair of acute dissection [32]. Although results
from a recent multi-center analysis of patients undergoing total arch replacement
with or without FET demonstrated no increase in risk of spinal cord injury with the
addition of FET to a total arch—4% for total arch replacement and 6% for FET [33].
This data suggests that the exact mechanisms of spinal cord injury are yet to be
elucidated. The risk is likely related to extent and pattern of disease as much as it is
to the techniques used to address it. Improvements in technique and a concerted
effort to reduce the circulatory arrest time may help to reduce neurologic risks as the
experience improves.
The largest single center series from Beijing have demonstrated excellent results
with mortality of 6.5%, stroke 2%, and spinal cord injury of 2.4% [34]. It is important to note that the patient population in the Chinese series was about 10 years
younger (mean 46 years old) than their European and American counterparts. Also,
the mean time from dissection to operation was 5 days so this likely represents a
select population of patients who are less likely to have the severest forms of malperfusion. Malperfusion at presentation has repeatedly been shown to be an important predictor of acute outcomes and the addition of FET to acute repair may prove
to be benecial in these patients as the technique optimizes distal true lumen ow
[35, 36].
The primary advantage of the B-SAFER technique is that it allows for repair of
the entire ascending, arch, and proximal descending aorta in one relatively efcient
operation with a limited period of circulatory arrest. In the early experience with
this technique, the results were good with mortality, stroke, and spinal cord injury
risk of 4%, respectively. In patients in whose dissection extends only into the arch,
this can be the denitive procedure. In those who have residual thoracoabdominal
dissection, the residual dissected segment beyond the FET component can be easily
addressed with a future endovascular repair [37, 38].
The Future
Next generation frozen elephant trunk devices feature additional branch limbs arising from the surgical graft component and easier to use delivery and deployment
systems (Thoraex, TerumoAortic, Scotland—Fig. 4a; EvitaNeo, Cryolife,
330
Branches for head vessel
t
Release handle
ab
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management
Vascular graft
part
E. Germano et al.
Collar
Perfusion port
Stent graft par
Release trigger
Control handle
Protective wire
Graft
protector
Pusher
Tip (36F)
Release wire
Fig. 4 Commercially available (in Europe; investigational in US) dedicated frozen elephant trunk
devices: (a) Thoraex, TerumoAortic and (b) EVITA Open Neo, Cryolife. Images provided by
manufacturers
Atlanta—Fig. 4b). Additional devices that are currently in trial include a bare stent
that extends across the arch with or without and additional descending stentgraft
component.
Our experience with the B-SAFER technique has continued and now accounts
for the majority of acute DeBakey Type 1 repairs and chronic aortic dissection
repairs performed in our center. The operation has been performed by nine of our
staff surgeons in over 250 patients. We are currently actively enrolling patients in a
physician sponsored investigational device exemption study to allow for prospective assessment of the outcomes for this procedure. Additional advances in the
development of frozen elephant trunk repair devices are likely to include built-in
branch grafts to accommodate the left subclavian artery and to further simplify
extended repair.
Although progress has been slow, it has been steady and we should continue to
see improvements in the care of aortic dissection with the use of frozen elephant
trunk techniques becoming the new standard of surgical treatment.
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E. Germano et al.
One-Stage Repair ofExtensive Chronic
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Thoracic Aortic Dissection
AlexanderKulik andNicholasT.Kouchoukos
Introduction
Following successful repair of acute type A aortic dissection with graft replacement
of the ascending aorta and part of the aortic arch, the false lumen frequently remains
patent. Progressive dilation of the remaining dissected aorta may thereafter develop
[1, 2], occurring most commonly in younger patients and those with connective tissue disease (Marfan syndrome) [3–5]. Ultimately, up to 30% of patients will require
operative re-intervention for aneurysmal disease or progressive aortic valve insufciency 5–10 years after the initial dissection surgery [1–4, 6–10]. Late reoperations for thoracic aortic dilation may also be necessary for patients who develop
aortic dissection after coronary or valve operations [11–13], and for those who
develop retrograde dissection and enlargement of the aortic arch following type B
aortic dissection or endovascular stent-graft repair of the thoracic aorta [14–16].
While several operative techniques exist, the optimal surgical approach for the management of patients who develop substantial enlargement of the remaining dissected
thoracic aorta has yet to be determined. Options for management include staged
procedures, commonly using conventional [17–19] or frozen elephant trunk techniques [20–23], hybrid procedures using endovascular grafts to exclude the aneurysmal thoracic aortic segments [24–26], and 1-stage procedures [27–29]. Herein,
we present our experience with the 1-stage technique which we have used exclusively since 1995 for patients with chronic thoracic aortic dissection who require
A. Kulik (*)
Lynn Heart and Vascular Institute, Boca Raton Regional Hospital, Boca Raton, FL, USA
Florida Atlantic University, Boca Raton, FL, USA
N. T. Kouchoukos
Division of Cardiovascular and Thoracic Surgery, Missouri Baptist Medical Center, BJC
HealthCare, St. Louis, MO, USA
Washington University School of Medicine, St. Louis, MO, USA
J. S. Coselli et al. (eds.), Aortic Dissection and Acute Aortic Syndromes,
https://doi.org/10.1007/978-3-030-66668-2_24
333© Springer Nature Switzerland AG 2021
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A. Kulik and N. T. Kouchoukos
extensive resection of the descending thoracic aorta. We have focused on the details
of the surgical technique, and have highlighted the early and late clinical outcomes
associated with the procedure.
Technique
Previously reported [27, 30–33], our operative technique involves the use of bilateral anterior thoracotomy incisions through the fourth intercostal space and a
transverse sternotomy (Fig. 1). Peripheral venous cannulation is performed
through the right common femoral vein using a 2-stage cannula with the tip positioned in the superior vena cava, and arterial cannulation is achieved through the
right common femoral artery and the right axillary artery. For axillary cannulation, through a right subclavicular incision, an 8- or 10-mm collagen-impregnated
polyester graft (Hemashield Platinum straight tube graft; MAQUET Cardiovascular
LLC, Wayne, NJ) is sutured to the axillary artery in an end-to-side fashion and the
graft is then connected to the cardiopulmonary bypass (CPB) circuit (Fig.2a, b).
Two separate arterial lines from the pump oxygenator are used during aortic arch
operations, and the desired ratio of ow through the two arterial lines is achieved
Fig. 1 Patient is positioned in a modied right lateral decubitus position. Dashed lines indicate
sites of incision. (From Kouchoukos [33])
One-Stage Repair ofExtensive Chronic Thoracic Aortic Dissection
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335
ab
cannula with tip in SVC
Rt Axillary a.
Arterial line
Fig. 2 (a) Axillary artery graft. (From Kouchoukos [33]]. (b) Right femoral artery and vein can-
nulation. (From Kouchoukos [33])
Cannula in femoral a.
Two-stage venous
during the operation by using occluders and in-line owmeters. The femoral arterial line is initially clamped, and CPB is established using the axillary perfusion
graft. Cooling is then initiated, and a catheter is inserted into the right superior
pulmonary vein for venting the left heart. A cannula is also inserted into the coronary sinus for delivery of cold blood cardioplegic solution (Fig.3). During cooling the head is packed in ice and intravenous methylprednisolone (7–10mg/kg)
and thiopental (10–15mg/kg) are administered. The pericardium is incised over
the distal ascending aorta and aortic arch, and the left phrenic and left vagus
nerves are identied and protected without isolation or traction. If the ascending
aorta can be safely clamped, additional antegrade cardioplegia is administered
(Fig.4). When the nasopharyngeal temperature reaches 13–18°C and the electroencephalogram becomes isoelectric, circulatory arrest is established. The axillary
perfusion graft is clamped and the ascending aorta and aortic arch are opened with
care to prevent dislodgment of atheromatous debris. The brachiocephalic arteries
are dissected from the surrounding tissue and transected at their origins from the
aorta. In the presence of atheroma or dissection, the arteries may require division
more distally (Fig.5). Perfusion from the axillary artery is then slowly initiated to
evacuate trapped air and debris (Fig.6). The arteries are ushed and individually
clamped. Cerebral perfusion is then initiated from the right axillary artery graft
(ow 10–15mL/kg/min; temperature 20–22°C) to provide perfusion to the right
carotid and right vertebral arteries, and, through the circle of Willis and other collateral channels, to the left side of the brain. The ow rate is adjusted to maintain
a mixed venous oxygen saturation of 85–95% using bilateral cerebral oximetric
monitoring. Perfusion pressure is continuously monitored from the left radial
artery. A clamp is placed on the descending thoracic aorta distal to the aneurysmal
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