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In: Perspectives in Aortic Valve Disease ISBN: 978-1-53618-769-4
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Editor: Giovanni Concistrè © 2020 Nova Science Publishers, Inc.
Chapter 15
TOTALLY ENDOSCOPIC AORTIC VALVE
REPLACEMENT (EAVR)
Tommaso Hinna Danesi
Department of Cardiac Surgery, Osp. San Bortolo, Vicenza, Italia
ABSTRACT
In the last 15 years minimally invasive approach in cardiac surgery (MICS) become
a strong reality involving valvular and revascularization surgery. A variety of different
surgical approaches are described as minimally invasive, but may be be substantially
different one from another.
The trend of wound’s reduction requires the application of the thoracoscope in order
to perform surgery under indirect vision; this is the era of endoscopic minimally invasive
cardiac surgery (Endoscopic MICS) or cardiac endoscopy.
Performing surgery using videoscopy and long shaft instruments requires specific
skills and a wide expertise in other endoscopic surgeries such as mitral valve one should
be a pivotal startup.
All aspects of cardiac surgery are involved in this innovative procedure, including
the anesthesiological and cardio-pulmonary bypass setups.
Keywords: MICS, minimally invasive cardiac surgery, endoscopic cardiac surgery, cardiac
endoscopy, aortic valve replacement
INTRODUCTION
Over the past 15 years, minimally invasive cardiac surgery (MICS) has been increasingly
adopted especially with mitral valve surgery. Minimally invasive approach for the aortic
valve was often represented by mini-sternotomy.
, MD
Corresponding Author’s Email: tommasohinnadanesi@gmail.com.
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The MICS growth was driven by the desire to translate the benefits observed in other
surgery specialties, such as decreased pain, reduced surgical trauma, faster recovery and
meeting the patient’s needs to cardiac surgery.
The complexity of performing operations through a small incision, a reduced operating
field with no dedicated technologies, rudimentary minimally invasive instruments and the
compelling need of avoiding longer cross clamp time mitigated the initial enthusiasm.
However, innovation in perfusion techniques and devices, the devolpement of dedicated
surgical instruments and the availability of fast implanting bioprosthesis has made the way to
establish endoscopic MICS the standard of care in high volume centers in the current era.
MICS over a long period has undergone several changes with regard to techniques and
philosophy making it easier and reproducible, with surgical results comparable to the
conventional surgical approach.
In this chapter aortic valve replacement in an endoscopic fashion will be explored
referring to a surgery performed in a totally endoscopic under indirect vision where the use of
a thoracoscope is mandatory.
MINIMALLY INVASIVE CONCEPT
MICS and Endoscopic MICS
Figure 1 shows a right anterior thoracotomy (RAT) in which the divarication of the ribs
provides a large operative field and surgery can be performed under direct vision.
Figure 1. RAT in direct vision.
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There are several interpretations of minimally invasive concepts as shown in Figures 1, 2,
3.
Figures 2 and 3 show a minimally invasive RAT (MRAT). Both approaches are intended
as minimally invasive but there are several differences. First of all in MRAT the thoracoscope
is mandatory to perform surgery, otherwise the reduction of the skin incision does not allow
to preserve the natural stereo-vision of the operator and often the aortic valve should not be
directly visualized.
Figure 2. MRAT in thoracoscopic vision.
Figure 3. MRAT in thoracoscopic vision.
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The chapter will discuss only surgery performed trough MRAT in which the small skin
incision serves only to introduce the endoscopic surgical instruments, the plegia/root venting
line and the prosthetic valve.
This access is done without any rib spreading just wit the aid of soft tissue retractor and
any sacrifice of right mammary artery or cutting rib. The use of thoracoscope wit indirect
vision, the miniaturized skin incision, no rib spreading, dislocation or cutting and no right
mammary artery sacrifice are fundamental characteristics of endoscopic aortic valve MICS.
Rib spreading leads to postoperative pain ignoring one of the principles of endoscopic
MICS which is pain avoidance.
GENERAL CONSIDERATIONS
From the Society of Thoracic Surgery database (STS database), a minimally invasive
valve surgery is defined as the one not performed with a full sternotomy and with a CPB
support [1]. According to Chitwood et al., [2] MICS should not be defined in term of a
specific procedure, but rather a philosophy that requires an operation-specific strategy. Each
minimally invasive strategy introduces alternatives for CPB cannulation (central or
peripheral), aortic occlusion (endovascular or external trasnthoracic i.e., in mitral valve
surgery) and cardioplegia delivery (antegrade, atrial retrograde or transjugular retrograde) [23]. The concept of avoiding a full sternotomy translates into a wide range of surgical
procedures in which a partial sternotomy and a full length right thoracotomy are both
considered minimally invasive surgery.
Preoperative assessment of aortic patient candidates to MICS surgery is still debated, i.e.,
several centers consider a full aortic CT scan mandatory to assess the feasibility of fem-fem
cannulation. While in mitralic patients in which 60 t0 70% of mitral valve pathology is due to
degenerative disease and the average age of them is quite low a preoperative CT scan could
be considered useful to detect ascending aorta calcification affecting aortic cross clamp as
well as prediction of peripheral cannulation-related complications [4] in aortic population a
preoperative CT scan should be routinely performed.
Anesthesiological setup is not very different from conventional cardiac surgery. Although
double lumen endo-tracheal intubation is widespread this often is not mandatory. A
retrospective study on 96 patients from Kim et al., who underwent MICS procedure using a
single lumen tube or double lumen tube did not show any difference in ICU stay of failure in
fast track protocols [5].
Double lumen tube should be considered for patients with previous sternotomy and is
mandatory in redo patient with a previous right thoracotomy or a right lung procedure i.e.,
pleurodesis or chest tube insertion.
Central venous cannulation can be achieved through either the right or the left internal
jugular veins. the right subclavian vein should be generally spread because is proximal to the
insertion site of the Chitwood clamp which is placed in the 1st or the 2nd intercostal space
(ICS).
The right internal jugular vein may be also necessary for double venous CPB drainage in
case of elevated BMI patients or in redo cases.
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Cannulation techniques for MICS have constantly evolved over the past few years; until
2010 cannulation strategies evolved in our experience to favor peripheral femoral cannulation
over central ascending aorta one. [6] Percutaneous or surgical dual stages bicaval venous
drainage over a percutaneous adjunctive neck access and direct external aortic cross clamp
with Chitwood clamp.
Currently, the most common aortic valve minimally invasive approach is PortAccess
through RAT or MRAT, depending on the center preference or experience (direct or indirect
vision). Because our large experience with endoscopic Mitral Valve surgery and this
endoscopic approach is more attractive for both patients and surgeons we translate our
knowledge in the setting of aortic surgery.
PATIENT SELECTION AND PREOPERATIVE
ASSESSMENT FOR EAVR
In an experienced MICS center used to completely thoracoscopic surgery no Patient
selection is needed. The endoscopic indirect vision surgery is not affected by the position of
the aorta (several Centers needs a more than 50% of dextroposition of the aorta respect the
right margin-sternal line) [7].
The habitus of the Patient do not affect the surgical access because once the thoracoscope
is positioned in the right way every mediastinal structure is easily accessible.
Moving to a full video guided surgical procedure, no specific preoperative assessment is
needed. For medical and legal reasons a CT scan or Echo Color Doppler of groin’s vascular
axis can be made. It can be reasonable considering that aortic population is older than mitral
one and may present some vascular comorbidities such as aortopathy or lower limb
atherosclerosis precluding a safe aortic cross clamp or retrograde perfusion.
Once the endoscopic skills are well acquired a Patient undergoing to EAVR could follow
the same path of other standard surgery candidates.
OPERATING THEATRE SETUP AND PATIENT POSITIONING
EAVR does not need any specific setup except for the videocoloumn and the CO”
insufflator connected to the thoracoscope trocar. [8]
The patient must lay supine with an elevation of 30 to 40° of the right hemithorax. It can
be useful the use of an inflating pillet that can be deflated in case of need to convert the
procedure into a full sternotomy.
SURGICAL ACCESS
In endoscopic aortic valve replacement surgery (EAVR), the choice of the skin incision
and the ICS in the MRAT is crucial, in order to achieve a comfortable surgical
procedure.Usually the 2nd ICS is entered through a prepectoral skin incision performed above
the 3rd rib extended for 2 to 4 cm laterally from the midclavicular line. This is the “Working
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Port.” The incision over the 3rd rib easily allow to access the 3rd ICS in case the 2nd results
too high for a short ascending aorta.
The incorrect ICS or a very medial MRAT can result in an uncomfortable setup and may
lead to a more invasive needs such as rib dislocation, cutting or right mammary artery
sacrifice to improve the rib spreading and the operating field. If the chosen ICS is too high the
approaching angle, may be very uncomfortable making difficult any maneuver on the aortic
valve. There are not differences preparing men and women.
It is preferable to enter the ICS more laterally in order to achieve a better divarication of
the ribs which are more fix close to the sternum.
A soft tissue retractor is needed, it allows to gently increase the working port. Other two
5 mm incisions are needed: one in the 2nd or 1 st ICS laterally to the midclavicular line to
introduce the aortic clamp and one in the 3rd i.s. at the level of the anterior axillary line to
introduce the ventricular vent-line. These are the “Mini-Ports.”
CARDIOPULMONARY BYPASS
The small Working Port doesn’t allow direct aortic and right atrial cannulation may be
difficult and can steal lot of space of operating field. The CPB is instituted through femoral
vessels. Is mandatory to check the position of the venous guidewire into the superior vena
cava with TEE to avoid any atriocaval junction injury or malpositioning of the cannula
resulting in an inappropriate venous drainage.
The usage of the vacuum assisted venous drainage is mandatory. The vacuum should not
exceed -60 mmHg into the venous reservoir to avoid RBCs damage [9].
In large Patients (BSA > 1.9 m2) an additional venous drainage cannula can be
considered. Usually a 14 fr. cannula inserted into the right internal jugular vein is enough
[10].
AORTIC CROSS CLAMPING, CARDIOPLEGIA
AND VENTRICULAR VENTING
Aortic cross clamp is obtained using a Chitwood clamp, other clamps can be used too i.e.,
Cygnet and Glauber MIS clamps. Once the CPB has been instituted is mandatory to obtain a
gentle dissection of the transverse sinus to allow the aortic cross clamp as distal as possible
and avoiding any injury of the right branch of the pulmonary artery that may result in an
emergency conversion to full sternotomy.
As for mitral valve endoscopic surgery a root needle is putted in place and the
cardioplegia is delivered. Custodiol or Bretschneider cardioplegic solutions may be a valid
option giving lot of time free from adjunctive doses. If aortic regurgitation is present the first
shot may be delivered into the root and then the dose completed directly into the coronary
ostia.
Unfortunately the Working Port is too small to allow the positioning of a retroplegia
catheter, if desired additional neckline such as Propledge (Edwards Lifescience, Irvine CA)
can be used.
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The left ventricle is vented as usual through the superior right pulmonary vein and the
sump is passed through the 5 mm mini-port inte the 3rd I.S. Putting in place the purse string
and the tourniquet at this time may steel some operating field space making the Working Port
uncomfortable. If desired a percutaneous ventline can be used (Endovent by Edwards
Lifescience, Irvine, CA).
AORTIC VALVE ACCESS IN ENDOSCOPIC SURGERY
The 30° thoracoscope is essential and provides a magnified surgical view and allows to
navigate the mediastinum accessing alla cardiac structures involved in the operation;
sometimes the visualization results better than in standard surgery i.e., pulmonary veins and
Sondergaard groove.
Many attention must be paid to the aortotomy, in general concepts we must consider that
median structures toward the pulmonary artery are very difficult to reach from a right sided
access.
A good strategy should be to remove accurately the pleuro-pericardial fat, identify the
phrenic nerve to avoid any injury and then open the pericardium. This maneuver should be
attempted once the patient is on CPB in order to avoid any right atrium injury.
Once the pericardium has been opened our goal is to pull the target structures towards us
reducing the distance. Pericardial retraction stitches should be placed in order to achieve this
goal. Usually three stitches are enough to expose the aorta and the Sondergaard groove.
The aortotomy should be made considering the prosthetic valve chosen; a 3 to 3.5 cm
high aortotomy should be mad in case of sutureless valve implantation meanwhile a standard
J stick or italic S incision can be performed for standard stented or rapid deployment valves.
SURGICAL TECHNIQUE
Aortotomy
Aortotomy is made the right on possible avoiding any extension or tear towards the
pulmonary artery. This zone is very difficult to manage once the aorta has been declamped in
case of bleeding.
Three to four suspension stitches can be placed in order to maximize the exposition of the
aortic valve.
One stitch should be placed on the distal part of the ascending aorta and secured to the
pericardium avoiding any interference with the operating field by the distal stump of the
aorta. Other two or three stitches can be placed in order to open wide the aortic root and
achieve a better exposition of the aortic valve; we have to consider that just one Surgeon can
act into the operating field.
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Aortic Valve Replacement (AVR)
The aortic valve is normally excised and the annulus decalcified. The technique for AVR
implantation depends on the chosen prosthesis. If a standard biological or mechanical
prosthesis is chosen a standard technique of implantation can be adopted (2-0 polyester suture
with subannular pledgets); in case of Rapid deployment valve implantation three 2-0
polyester suture are required. Considering the small working space check with the
thoracoscope the correct position of the three tourniquets required for the implantation of
these kind of bioprosthesis; in some cases (discrepancy between non coronary sinus and
right/left coronary sinuses) we used to secure rapid deployment valves with at least six 2-0
polyester stitches. This technique increase the safety of a correct valve positioning
considering that the Working Port do not allow rude manipulation of the bioprosthesis such as
hard pushing into the annulus and allows or hard pulling of the stitches that may lead to an
annular damage.
If a sutureless bioprosthesis is chosen the thoracoscope allows to easily check the correct
positioning of the valve. Once the bioprosthesis has been released as a tip we suggest to
introduce the thoracoscope into the ventricle to check its correct positioning.
Aortorrhaphy
Start from the medial part of the aortotomy paying attention to that zone.
Deairing
EAVR does not allow an efficient deiaring as well as in standard sternotomic surgery, but
continuous CO2 inflation during the procedure significantly reduces gaseous emboli.
Electrodes
The small Working Port does not allow to easily reach a safe landing zone for the pacing
wire. This must be placed when the heart is empty because once the heart has been filled is no
longer possible to expose the right ventricle. If desired consider an endocavitary temporary
pacing.
Drainages
Two small 24 fr flexible silastic drains are enough to maintain an efficient drainage of the
chest. They can be passed through the miniports used to place te ventline and the clamp or the
thoracoscope.
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CONCLUSION
In conclusion EAVR is a safe, reproducible and appealing technique. Many attention
must be paid at the beginning in order to avoid failure which may leads to a minimally
invasive program stop. A large experience in minimally-invasive and endoscopic mitral valve
surgery may represent a must do to approach a safe EAVR.
A strong standardization of the procedure plays a key role in a successful Endoscopic
Cardiac Surgery Program.
REFERENCES
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robot-assisted mitral valve surgery. Surg. Laparosc. Endosc. Percutan. Tech.
2002;12:58-63.
[4] Enriquez-Sarano M, Akins CW, Vahanian A. Mitral regurgitation. Lancet
2009;373:1382-94.
[5] Kim HY, Baek SH, Je HG, Kim TK, Kim HJ, Ahn JH, Park SJ. Comparison of the
single-lumen endotracheal tube and double-lumen endobronchial tube used in
minimally invasive cardiac surgery for the fast track protocol. J. Thorac. Dis.
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[6] Chan EY1, Lumbao DM, Iribarne A, Easterwood R, Yang JY, Cheema FH, Smith CR,
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[7] A. Miceli, M. Murzi, D. Gilmanov, R. Fuga,’ M. Ferrarini, M. Solinas, et al. Minimally
invasive aortic valve replacement using right minithoracotomy is associated with better
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[10] UpToDate: Obesity in adults: Prevalence, screening and evaluation. Retrieved on
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