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Transcript of Robotic Cardiac Surgery
Journal of Long-Term Eff ects of Medical Implants, 13(6)451–464 (2003)
Document ID# JLT1306-451–464(206)
1050-6934/03 $5.00 © 2003 by Begell House, Inc.
Robotic Cardiac Surgery
Alan P. Kypson, MD, L. Wiley Nifong, MD, & W. Randolph Chitwood Jr., MD
Department of Surgery, Division of Cardiothoracic Surgery, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
Address all correspondence to Alan P. Kypson, Department of Surgery, Division of Cardiothoracic Surgery, Brody
School of Medicine, East Carolina University, 600 Moye Boulevard, Room 252, Greenville, North Carolina, 27858,
USA; [email protected]
ABSTRACT: Traditionally, cardiac surgery has been performed by median sternotomy. How-ever, a renaissance is occurring. Cardiac operations are being performed through smaller and alternative incisions with enhanced technological assistance. Both coronary artery bypass graft-ing and valve surgery can be accomplished with this novel methodology. Specifi cally, minimally invasive mitral valve surgery has become standard for many surgeons. At our institution, we have developed a robotic mitral surgery program with the da Vinci™ telemanipulation system. Th is system allows the surgeon to perform complex mitral valve operations through small port sites rather than a traditional median sternotomy. Our techniques and initial results are reported, as is a brief overview of the evolution of robotic cardiac surgery.
KEY WORDS: cardiac, surgery, robotic
Journal of Long-Term Effects of Medical Implants
A. P. KYPSON ET AL.
I. INTRODUCTION
Traditional cardiac surgery is performed through a
median sternotomy, which provides generous expo-
sure and access to all cardiac structures and the great
vessels. During the past decade, improvements in
endoscopic technology and techniques have resulted
in a substantial increase in the number of minimally
invasive noncardiac surgical procedures performed.
Unfortunately, because of the complexity of most
cardiovascular procedures, a median sternotomy and
cardiopulmonary bypass have been required.
However, in the early 1990s, alternative, less
traumatic methods for performing cardiothoracic
surgery were developed. Th e minimally invasive di-
rect coronary artery bypass (MIDCAB) provided a
single vessel bypass on the anterior surface of a beating
heart through a small anterior thoracotomy. Th e Port-
Access™ (Cardiovations Inc., Ethicon, Somerville,
New Jersey) method involved endoscopic cardiac
surgery on an arrested heart using novel closed-
chest cardiopulmonary bypass and cardioplegic ar-
rest methods.¹²
Nevertheless, there were many limitations that pre-
cluded the widespread adaptation of these methods.
For example, standard endoscopic instruments, with
only four degrees of freedom, reduce dexterity signifi -
cantly. Working through fi xed entry points (trocars),
operators have to reverse hand motions (fulcrum ef-
fect), and at the same time, instrument drag induces
the need for higher manipulation forces, leading to
hand muscle fatigue.³
Computer-enhanced instrumentation systems
have been developed to overcome these and other
limitations. Systems can be classifi ed according to the
tasks they help perform. Th e fi rst group functions as
an assisting tool that holds and positions instruments.
Th e Automated Endoscopic System for Optimal
Positioning (AESOP™ 3000, Computer Motion,
Inc., Santa Barbara, California) is typically used to
guide an endoscope, which is controlled using voice
activation. One can order the robot to hold a specifi c
position or reorient to a specifi c operative fi eld, pro-
viding a clear and steady view without tremor. Th e
second group consists of telemanipulators that were
invented to facilitate fi ne manipulations done under
remote conditions. Connected through a controller
panel, the operator’s motions direct the remote ma-
nipulator or end-eff ector. Currently, in cardiac surgery
there are two telemanipulation systems in use—the
da Vinci™ (Intuitive Surgical, Inc., Mountain View,
California) and the Zeus™ robotic system (Computer
Motion).
Th e da Vinci™ system comprises three compo-
nents; a surgeon console, an instrument cart, and a
visioning platform (Fıg. 1). Th e operative console is
physically removed from the patient and allows the
surgeon to sit comfortably and ergonomically with
his/her head positioned in a three-dimensional vi-
sion array. Th e surgeon’s fi nger and wrist movements
are registered digitally, through sensors, and these
FIGURE 1A. da Vinci™ robotic telemanipulation system:
operative console where the surgeon is seated.
ROBOTIC CARDIAC SURGERY
Volume 13, Number 6, 2003
actions are transferred to an instrument cart, which
operates the synchronous end-eff ector instruments
(Fıg. 2). “Wrist-like” instrument articulation emulates
the surgeon’s actions at the tissue level, and dexterity
becomes enhanced through combined tremor sup-
pression and motion scaling. A clutching mechanism
enables readjustment of hand position to maintain an
optimal ergonomic attitude with respect to the visual
fi eld. Th e three-dimensional digital visioning system
enables natural depth perception with high-power
magnifi cation (10×). Visualization of the internal
thoracic artery, coronary arteries, and mitral appa-
ratus is excellent.
Th e Zeus™ system comprises three interactive arms,
mounted directly on the operating table (Fıg. 3). Al-
though the Zeus™ system lacks a fully articulated wrist
and allows only four degrees of freedom, the instru-
ment diameter is only 3.9-mm compared with the 7-
mm da Vinci arm. Th e surgeon also works at a console
that controls the instrument arms. Th e basic Zeus™
visualization system is two-dimensional; however, it
can be used in combination with an independently
developed three-dimensional visualization system.
FIGURE 1B. da Vinci™ robotic telemanipulation system:
the instrument cart.
FIGURE 2. da Vinci™ robotic telemanipulation system:
end-effector arms demonstrating all axis of motion.
FIGURE 3A. Zeus™ surgical console. Note the two-di-
mensional monitor the surgeon uses.
Journal of Long-Term Effects of Medical Implants
A. P. KYPSON ET AL.
II. EVOLUTION OF ROBOTIC CARDIAC SURGERY
Given the availability of telemanipulative systems,
endoscopic robotic cardiac operations have become
possible and have evolved through graded levels of
diffi culty with increasingly less exposure to a progres-
sive reliance on video assistance. In this scheme, entry
levels of technical complexity are mastered premoni-
tory to advancing past small incision, direct-vision
approaches (Level I), toward more complex video-
assisted procedures (Levels II-III), and fi nally, to
robotic cardiac operations (Level IV).
II.A. Level I: Direct Vision and Mini-Incisions
Initially, minimally invasive cardiac valve surgery
was based on modifi cations of previously used
incisions and performed under direct vision. In
1996, mini-sternotomies, parasternal incisions, and
mini-thoracotomies were used in the fi rst minimally
invasive aortic valve operations.⁴⁶ In Cosgrove’s fi rst
50 aortic procedures, operative times approximated
conventional operations, and mortality was 2%, with
half of the patients being discharged by postoperative
day fi ve.⁵ Cohn⁴ presented his series of 41 minimally
invasive aortic operations and demonstrated economic
benefi ts. Others⁶⁹ also found that minimal access in-
cisions provided adequate exposure of the mitral valve.
Surgical mortality (1–3%) and morbidity were com-
parable to those of conventional mitral surgery. Falk
reported on 24 mitral valve repairs performed through
a mini-incision with Port-access™ techniques.¹⁰ By
1997, the New York University group had done 27
Port-access™ mitral repairs/replacements with one
death. Th ere were no aortic dissections and no repairs
had residual regurgitation requiring reoperation.¹¹
Port-access™ methods were also used for coro-
nary artery bypass operations.¹²¹³ Th rough incisions
other than a median sternotomy, cardiac standstill was
feasible, allowing surgeons to graft multiple vessels.
Port-access™ coronary operations proved effi cacious
although they were more complex and required longer
perfusion times. Results of a prospective multicenter
trial¹⁴ on 302 consecutive patients demonstrated an
operative mortality of 0.99%, with a 3.3% incidence
of reoperation for bleeding and a 1.7% incidence
of stroke. Th ese encouraging results confi rmed the
feasibility and safety of these techniques and further
advanced the next level of “minimal invasiveness.”
II.B. Level II: Video-Assisted and Micro-Incisions
Video assistance was fi rst used for closed chest in-
ternal mammary artery harvests and congenital heart
operations.¹⁵¹⁷ Although Kaneko¹⁸ fi rst described the
use of video assistance for mitral valve surgery done
through a sternotomy, it was Carpentier¹⁹ who in Feb-
ruary 1996 performed the fi rst video-assisted mitral
valve repair via a minithoracotomy using ventricular
fi brillation. Th ree months later, our group performed a
mitral valve replacement using a microincision, video-
scopic vision, percutaneous transthoracic aortic clamp,
and retrograde cardioplegia.²⁰²¹ In 1998, Mohr re-
ported 51 minimally invasive mitral operations using
FIGURE 3B. Zeus™ instrument arms. Note that they are
mounted directly to the surgical table.
ROBOTIC CARDIAC SURGERY
Volume 13, Number 6, 2003
Port-access™ technology, a 4-cm incision, and three-
dimensional videoscopy. Video technology was helpful
for replacement and simple repairs; however, complex
reconstructions were still approached under direct vi-
sion.²² Concurrently, our group reported 31 patients
using video-assistance with a two- dimensional 5-mm
camera. Complex repairs were possible and included
quadrangular resections, sliding valvuloplasties, and
chordal replacements with no major complications
and mortality less than 1%.²³
Unfortunately, early attempts at coronary revas-
cularization with long instruments through small
incisions proved futile. Surgeons began to also use
voice-activated robotic camera control to harvest in-
ternal mammary arteries with excellent facility and
less patient trauma than experienced by conventional
means.¹⁶ Th e addition of three-dimensional visual-
ization, robotic camera control, and instrument tip
articulation were the next essential steps toward a
totally endoscopic procedure where wrist-like instru-
ments and three-dimensional vision could transpose
surgical manipulations from outside the chest wall to
deep within the mediastinum.
II.C. Level III: Video-Directed and Port Incisions
In 1997, with the assistance of AESOP™ 3000,
cardiac surgery entered the robotic age and allowed
smaller incisions with better mitral valve and subval-
vular visualization.²⁴ Th e following year, we performed
the fi rst video-directed mitral operation in the United
States using the AESOP™ 3000 robotic arm and a
Vista™ (Vista Cardiothoracic Systems, Westborough,
Massachusetts) three-dimensional camera.²⁰²¹ Visual
accuracy was improved by voice manipulation of the
camera. We now use the robotic arm, endoscope, and
a conventional two-dimensional monitor routinely
and have done over 300 videoscopic mitral operations
successfully using this method. Recently, we reported
on the use of this approach²⁵ and compared the results
to a cohort who underwent conventional sternotomy.
Reduced bleeding, ventilator times, and hospital stays
were shown for the minimally invasive cohort.
II.D. Level IV: Video-Directed and Robotic Instruments
In 1998, Carpentier²⁶ performed the fi rst mitral valve
repair using an early prototype of the da Vinci™. Two
years later,²⁷ our group performed the fi rst complete
repair of a mitral valve in North America using the
da Vinci™ system. A trapezoidal resection of a large
P₂ was performed with the defect closed using mul-
tiple interrupted sutures, followed by implantation of
a #28 Cosgrove annuloplasty band. Subsequently, we
have performed over 70 other mitral repairs as part
of Food and Drug Administration (FDA)-approved
trials. To date, more than 250 mitral operations have
been done between Europe and North America using
the da Vinci™ system. Complex mitral repairs can
be done with reasonable cross clamp and perfusion
times as well as excellent midterm results. Repairs
have included annuloplasty band insertions, chordal
replacements, sliding valvuloplasties, chordal trans-
fers, and leafl et resections. Th e advancements in three-
dimensional video and robotic instrumentation have
progressed to a point where totally endoscopic mitral
procedures are feasible. In fact, Lange and associates²⁸
performed a totally endoscopic mitral valve repair
using only the 1cm ports with da Vinci™. Future
refi nements in these devices are needed to apply this
new technology more widely.
In May of 1998, Mohr and Falk harvested the
left internal mammary artery (LIMA) with the
da Vinci™ system and performed the fi rst human
coronary anastomosis through a small left anterior
thoracotomy incision.²⁹³⁰ More recently, work with
da Vinci™ has lead to FDA approval for internal
mammary harvesting in the United States.
Th e fi rst totally endoscopic coronary artery bypass
(TECAB) was performed on an arrested heart at the
Broussais Hospital in Paris³¹ using an early proto-
type of the da Vinci™ system. Th e Leipzig group
attempted a total closed chest approach for LIMA
to left anterior descending coronary artery (LAD)
grafting on the arrested heart in 27 patients and were
successful in twenty-two.³² Furthermore, surgeons
in Europe improved the initial da Vinci™ coronary
Journal of Long-Term Effects of Medical Implants
A. P. KYPSON ET AL.
method and eventually were able to complete bilat-
eral internal mammary artery grafts off -pump to the
anterior descending and right coronary arteries while
working from one side of the chest.³³³⁴
In September of 1998, Reichenspruner³⁵ performed
an endoscopic robotically assisted coronary anasto-
mosis using the Zeus™ system. He used a standard
myocardial stabilizer inserted through a mini-thora-
cotomy. Th e pericardiotomy, vascular occlusion, and
dissection of the LAD were all manually performed
using conventional instruments. Damiano³⁶ fi rst ex-
panded coronary surgery with Zeus™ to the United
States; and Boyd, at the London Health Services
Center in Canada, reported on six successful closed-
chest beating-heart single-vessel revascularizations
using the same system.³⁷ Despite early procedural
success, future refi nements in these devices are needed
to apply this new technology more widely.
III. CLINICAL APPLICATIONS/PATIENT SELECTION
Early in the development of any minimally invasive
cardiac surgery program, strict inclusion and exclusion
criteria should be followed. In our initial experience
with robotic mitral repairs, all patients had isolated
mitral insuffi ciency. Patients with a previous right
thoracotomy were excluded from the da Vinci™ pro-
cedures; however, we now approach these patients with
a video-assisted mitral valve operation. Patients with
severely calcifi ed mitral annulus are not candidates. De-
calcifi cation requires further instrument development
as well as a reliable means to evacuate any calcium that
may fall into the left ventricle. Patients with mitral valve
stenosis were excluded in the early FDA trials; however,
patients treatable by commissurotomy would be suitable
candidates for robotic repair. Th e improved visualiza-
tion of the valve and subvalvular apparatus along with
the maneuverability of bladed microinstruments would
facilitate performance of a commissurotomy.
As previously discussed, early eff orts at totally
endoscopic coronary surgery using conventional
instruments were discouraging and were hampered
with imprecision and two-dimensional visualization.
With the development of computer-assisted telema-
nipulation systems and three-dimensional visualiza-
tion, TECAB has not only become feasible but has
also been demonstrated to be safe. Nevertheless, with
current technology, these operations are usually per-
formed on single vessel (LAD) disease with either
an arrested heart using the Port-Access™ system, or
a beating heart using specially designed endoscopic
stabilizers. Clinical trials are currently underway in
Europe and North America.
IV. OPERATIVE TECHNIQUES
IV.A. Mitral Valve Surgery
Pre- and postoperative surface and transesophageal
echocardiographic (TEE) studies are performed. Pa-
tients are anesthetized and positioned with the right
chest elevated 30°–40° and the right arm suspended,
padded, and positioned over the forehead. Single left-
lung ventilation is used for complete intrathoracic
exposure.
Cardiopulmonary bypass is established at 26 °C
using femoral arterial infl ow and kinetic venous drain-
age through a femoral (21–23 Fr) and right internal
jugular vein (17 Fr) cannula. If the femoral artery is
too small or atherosclerotic, either a Bio-Medicus™
(Medtronic, Minneapolis, Minnesota, USA) or Di-
rectfl ow™ (Cardiovations, Somerville, New Jersey,
USA) cannula can be placed through a second inter-
space port for antegrade aortic perfusion. A 4–5 cm
infra-mammary incision is used, and a subpectoral
fourth-intercostal space (ICS) mini-thoracotomy is
developed to provide cardiac access. Th e pericardium
is opened under direct vision 2 cm anterior to the
phrenic nerve. Antegrade cardioplegia is given by an
aortic needle/vent placed either under direct vision
or videoscopically. To minimize intracardiac air en-
trainment, the thoracic cavity is fl ooded continuously
with carbon dioxide at 1–2 liters per minute. A trans-
thoracic aortic cross-clamp (Scanlan International,
Minneapolis, Minnesota, USA) is positioned in the
ROBOTIC CARDIAC SURGERY
Volume 13, Number 6, 2003
midaxillary line via a 4-mm incision in the third ICS,
and intermittent antegrade cold blood cardioplegia
maintains cardiac arrest and myocardial protection.
Under video-assisted guidance, the posterior tine of
the clamp is passed through the transverse sinus with
care taken not to injure the right pulmonary artery,
left atrial appendage, left main coronary, or aorta.
After cardioplegic arrest, a transthoracic retractor
is used to expose the mitral valve through a 3–4 cm
left atriotomy made medially to the right superior
pulmonary vein entrance (Fıg. 4).
After valve inspection, positions for da Vinci™ left
and right arm port incisions are determined. Th e right
trocar is placed in the fourth ICS posterior lateral to
the incision and parallel to the right superior pulmo-
nary vein. Occasionally, the fi fth ICS provides a better
angle for the right robotic arm. Th e left trocar generally
is placed 6 cm cephalad and medial to the right trocar,
insuring internal clearance between arms to avoid both
external and internal confl icts. Optimal robotic arm
convergence avoids left atrial wall tearing during in-
strument manipulations. A high-magnifi cation camera
is used with a 30° (looking up), 3D endoscope placed
through the medial portion of the mini-thoracotomy.
Th e remainder of the incision is used as a working port
for the assistant. Needles are retrieved using a long
magnetic device, and suture remnants are removed
from the surgical fi eld using vacuum assistance.
Operative procedures are performed from the
surgeon’s console placed approximately ten feet from
the operating table but in the same operating room.
Th e patient-side assistant changes instruments and
supplies and retrieves operative materials. Most often
an annuloplasty band (Edwards Lifesciences, Irvine,
California, USA) has been used to support repairs or
provide annular reduction. In video-assisted robotic
cases, early placement of annuloplasty sutures facili-
tates exposure during complex repairs. Exposure of
each new suture often becomes predicated on retrac-
tion of the previous one. Leafl et resections, papillary
muscle reconstruction, and chord insertions or trans-
positions should be performed after annular sutures
are completed and suspended. Each suture is placed
and tied intracorporeal. Upon completion of the re-
pair, robotic devices are removed, and the left atrium
is closed under direct vision to decrease operative
times. Standard de-airing and weaning procedures
are performed under TEE control. A typical robotic
mitral valve repair is depicted in Fıgure 5. One month
FIGURE 4. Operative view through the working port.
Note the excellent view of the mitral valve apparatus
with the left atrial retractor in place seen exiting through
the chest wall.
FIGURE 5. Typical da Vinci™ mitral valve repair: the P2 seg-
ment of the posterior leafl et is being resected by robotic
microscissors. The annulus is reduced and both P1 and P3
are approximated.
Journal of Long-Term Effects of Medical Implants
A. P. KYPSON ET AL.
after discharge, all patients return for a follow-up visit
and a transthoracic echocardiogram.
IV.B. Coronary Artery Bypass Surgery
Patients are intubated with a dual-lumen endotra-
cheal tube, allowing single right-lung ventilation. Th e
patient is placed on the operating room table in a
supine position with the left side of the chest elevated
about 30°, with the left arm placed along the body
below the midaxillary line. Th oracic landmarks such
as the sternal notch, xiphoid, and ribs are marked
for external orientation and port placement. Proper
port placement is essential for initiating endoscopic
mammary artery harvesting. After defl ation of the
left lung, the camera port is placed bluntly in the fi fth
intercostal space on the anterior axillary line. Th e chest
is insuffl ated with continuous CO₂ at pressures of
5–10 mm Hg to increase the available space between
the heart and sternum. An endoscope is placed into
this port and under visual control; two more port sites
are placed, usually in the third and seventh intercostal
spaces above the anterior axillary line, for both robotic
arms, forming a triangle. Th e LIMAis mobilized from
the subclavian artery all the way down to the distal
bifurcation with a 30° endoscope. Th e distal end is
skeletonized with the concomitant veins and fascia
left intact to provide countertraction.
After LIMA harvesting, the patient is placed on
cardiopulmonary bypass through femoral vessel can-
nulation if the procedure is being performed on an
arrested heart. Otherwise, attention is turned to the
pericardium, which is opened. Th e target vessel (LAD)
is identifi ed and sharply dissected free. For beating
heart operations, a 1-cm skin incision is created at
the subxiphoid area, and an endoscopic stabilizer is
introduced. Th is stabilizer resembles conventional off -
pump stabilizers and consists of two arms that contain
special slots for attachment of silastic vessel loops used
for coronary artery occlusion during the creation of
the anastomosis (Fıg. 6). An irrigation tube is attached
to this endo-stabilizer, allowing saline fl ushing for
clear visualization of the desired area. After placing
the stabilizer onto the LAD, blood fl ow through this
vessel is temporarily interrupted using silastic loops.
After incision of the LAD with the robotic system,
the anastomosis is completed on a beating heart using
7-0 polypropylene running suture. After completion
of the procedure, chest tubes are placed through the
camera port and the instrument port.
V. CLINICAL OUTCOMES
Currently, the world experience with robotic mitral valve
surgery is mostly anecdotal, retrospective, and noncon-
trolled. Nevertheless, surgical results thus far have been
encouraging and are hastening the way toward a com-
pletely endoscopic, robotic mitral valve operation.
FIGURE 6. Coronary stabilizer placed endoscopically as
used for TECAB. Note the irrigator that provides a clear
view for creation of the anastomosis.
ROBOTIC CARDIAC SURGERY
Volume 13, Number 6, 2003
Recently, we published our results of the fi rst 38
mitral repairs with the da Vinci™ system.³⁸ Total
robot time represents the exact time of robot deploy-
ment after valve exposure and continues until the end
of annuloplasty band placement. Th is time decreased
signifi cantly from 1.9 hours in the fi rst group of 19
patients to 1.5 hours in the second group. At the same
time, leafl et repair times fell signifi cantly from 1.0
hour to 0.6 hours, respectively. Also, total operating
times decreased signifi cantly from 5.1 hours to 4.4
hours in the second group of patients. Furthermore,
both cross-clamp and bypass times decreased signifi -
cantly with experience as well. For all patients, the
total length of stay was 3.8 days, with no diff erence
between the two groups. Of all patients in the study,
84% demonstrated a grade 3 or greater reduction in
mitral regurgitation at follow-up. In the entire series
there were no device-related complications or opera-
tive deaths. One valve was replaced at 19 days because
of hemolysis secondary to a leak that was directed
against a prosthetic chord.
In reviewing the Leipzig robotic mitral experi-
ence, Mohr described 17 patients that underwent
robotic mitral valve repair.³ Fourteen of the 17
patients underwent a successful mitral valve re-
pair with the da Vinci™ system. In three patients,
conversion to conventional endoscopic instruments
became necessary. Th e average cross clamp time was
89 ± 18 minutes. Following the repair, intraoperative
TEE demonstrated no regurgitation in 13 patients
and trace regurgitation in three. One patient had a
grade 2 leak requiring immediate endoscopic valve
replacement. Postoperative results were notable for
one failure of a repair requiring emergent valve
replacement on postoperative day 3 secondary to a
disrupted annuloplasty ring.
To date, we have completed over 60 robotic mitral
valve repairs with the da Vinci™ system and have
noted certain trends. For example, bypass and cross-
clamp times between the fi rst 25 patients and the
second group of 25 patients continue to signifi cantly
decrease and are currently averaging 2.69 and 2.12
hours, respectively. Suture placement time for annu-
loplasty rings has decreased signifi cantly from 2.15
minutes per suture to 1.46 minutes in the second
group. When P₂ robotic repair times were compared
from the fi rst group of 25 to the second, there was
a signifi cant decrease from 54.19 minutes to 30.79
minutes. A multicenter da Vinci™ trial enlisting
112 patients has recently been completed and dem-
onstrates effi cacy and safety in performing these
operations by multiple surgeons at various centers,
thereby becoming the fi rst robotic telemanipulation
system to become FDA approved for mitral valve
repair surgery.
Similarly, experience with endoscopic coronary
artery bypass surgery has been limited to only a
few centers, and results are highly controlled. Be-
cause the success of coronary surgery depends on
multiple, complex steps culminating in the creation
of a vascular anastomosis, most clinical series have
introduced robotically assisted coronary surgery in
a stepwise fashion. Specifi cally, initial experience is
limited to endoscopic LIMA harvesting, followed by
a robotically assisted anastomosis through a median
sternotomy, and fi nally a total endoscopic procedure
performed on an arrested heart followed by a beating
heart operation.
Currently, the largest published series of TECAB
come from Europe. Wimmer-Grenecker’s group in
Frankfurt reported on 45 patients that underwent
TECAB on an arrested heart.³⁹ Most of these (82%)
were single-vessel bypass (either LIMA–LAD or
right internal mammary artery to right coronary
artery). Th e fi rst 22 patients had angiograms prior
to discharge, revealing a 100% patency rate. Mean
operative time for single-vessel TECAB was 4.2 ±
0.9 hours and 6.3 ± 1.0 hours for double-vessel bypass
procedures. Th e average cross clamp time for single
bypass was 61 ± 16 minutes and 99 ± 55 minutes
for double bypass. Th e initial conversion rate of 22%
decreased to 5% in the last 20 patients, refl ecting an
obvious learning curve.
Kappert⁴⁰ described TECAB in 37 patients, of
which 29 were performed on a beating heart. Of
these 29 patients, three received double vessel bypass
using bilateral mammary arteries, and the rest were
revascularized with a LIMA–LAD. As experience was
Journal of Long-Term Effects of Medical Implants
A. P. KYPSON ET AL.
gained, the duration of surgery decreased noticeably
from 280 ± 80.2 to 186 ± 58.6 minutes. An average
of 30 ± 6.5 minutes for robotically performed anas-
tomosis versus 12 ± 3 minutes for directly hand-sewn
anastomoses was observed. Nevertheless, none of the
37 patients revealed any sign of delayed wound heal-
ing, but three patients did undergo a reexploration for
bleeding. Currently, midterm follow-up angiography
is being performed to assess graft patency.
In the United States, Damiano and colleagues⁴¹
initiated multicenter clinical trials on robotically
assisted coronary surgery using the Zeus™ system.
In his FDA safety and effi cacy trial, 19 patients
underwent a median sternotomy with cardioplegic
arrest of the heart. All grafts were sewn by hand in a
traditional manner except the LIMA–LAD, which
was sewn robotically. Seventeen had adequate intra-
operative fl ow (mean 38.5 ± 5 mL/min) in the LIMA
graft. Anastomotic time was 22.5 ± 1.2 minutes. One
patient underwent reexploration for mediastinal hem-
orrhage. At eight weeks’ follow-up, graft patency was
assessed by angiography and all grafts were open. Th e
average hospital stay was 4.1 ± 0.4 days.
Boyd and associates³⁷ from London Health Sci-
ences Center in Ontario, Canada, have also been
extensively involved in initial endoscopic coronary
surgery trials with the Zeus™ system. In 2000, he
published a report on a series of six patients that
were the fi rst to undergo TECAB in North America
on a beating heart using a specialized endoscopic
stabilizer. Each of these patients had single-vessel
LAD disease and underwent LIMA–LAD grafting.
Special 8-0 polytetrafl uoroethylene suture 7 cm in
length was used to minimize suture time placement.
Intracoronary shunts were used to provide needle
depth landmark when performing endoscopic anas-
tomosis with two-dimensional cameras. LIMA
harvest time averaged 65.3 ± 17.6 minutes (range
50–91 min). Th e anastomotic time was 55.8 ± 13.5
minutes (range 40–74 min) and median operative
time was 6 hours (range 4.5–7.5 h). All patients had
angiographically confi rmed patent grafts before leav-
ing the hospital. Th e average hospital length of stay
was 4.0 ± 0.9 days.
V.A. Limitations
Th e early clinical experience with computer-enhanced
telemanipulation systems has defi ned many of the
limitations of this approach despite rapid procedural
success. Th e lack of force feedback is currently being
addressed, and a strain sensor is being incorporated
into advanced robotic surgical tools that may allow
for greater control of force applied at the robotic end-
eff ector.⁴² Furthermore, conventional suture and knot
tying add signifi cant time. Advancements, such as
nitinol U-clips™ (Coalescent Surgical, Sunnyvale,
California, USA) should decrease operative times sig-
nifi cantly. In a series of experiments at East Carolina
University, average suture/clip placement times and
knot tying/deployment times signifi cantly decreased
from 4.9 minutes to 2.6 minutes by using clips. When
implanting mitral annuloplasty bands, a clip deploy-
ment time of 0.75 minutes versus 2.78 minutes for
suture tying was noted.⁴³ Because of these promis-
ing results, we have begun using the U-clip™. To
date, four patients have had mitral annuloplasty ring
implantation performed (Fıg. 7) and intraoperative
times have been analyzed. Fırst, there is no diff er-
ence between the placement times of the U-clip™
and conventional suture (1.1 ± 0.5 vs. 1.5 ± 0.9 min).
Most likely, this is because the motion of placing a
U-clip™ and a suture is the same. However, U-clip™
deployment time is signifi cantly less than suture tying
time. Th e average deployment time of a suture is 1.1 ±
0.7 minutes versus 0.5 ± 0.2 minutes for the U-clip™.
Th is novel technology may ultimately help reduce
cardiopulmonary bypass time and arrested heart times
in minimally invasive cardiac surgery.
For endoscopic coronary surgery, where port
placements are critical to the procedure’s success,
the potential use of image-guided surgical tech-
nologies will provide real-time data acquisition of
physiological characteristics, allowing one to better
assess the delivery of percutaneous therapy. Preop-
erative three-dimensional images of the thorax are
acquired by both computed tomography and electro-
cardiogram-gated magnetic resonance imaging and
are imported into a planning platform. A surgeon
ROBOTIC CARDIAC SURGERY
Volume 13, Number 6, 2003
may visualize and manipulate simulated objects in-
teractively, and once optimal access port placements
are determined, the positions of the simulated tools
can be recorded and marked directly on the patient to
specify positions for port incisions. Current research
being conducted in collaboration with Carpentier is
focusing on simulating and planning robotic proce-
dures. Surgeons will have a virtual platform to analyze
and plan optimal topographic surface targets that
would optimize port site placement.⁴⁴⁴⁵ Such three-
dimensional planning systems based on preoperative
imaging data have already been introduced into other
surgical specialties, including craniomaxillofacial and
orthopedic surgery.⁴⁶
VI. CONCLUSION
Clearly, advances in cardiopulmonary perfusion,
intracardiac visualization, instrumentation, and ro-
botic telemanipulation have hastened a shift toward
effi cient and safe minimally invasive cardiac surgery.
Today, cardiac surgery, particularly valve surgery done
through small incisions, has become standard practice
for many surgeons. Moreover, closed-chest coronary
bypass surgery is in its early developmental phases.
A renaissance in cardiac surgery has begun, and
robotic technology has provided benefi ts to cardiac
surgery. With improved optics and instrumentation, in-
cisions are smaller. Th e placement of wrist-like articula-
tions at the end of the instruments moves the pivoting
action to the plane of the operative fi eld. Th is improves
dexterity in tight spaces and allows for ambidextrous
suture placement. Sutures can be placed more accu-
rately because of tremor fi ltration and high-resolution
video magnifi cation. Furthermore, robotic systems may
serve as educational tools. In the near future, surgical
vision and training systems may be able to model most
surgical procedures through immersive technology.⁴⁷⁴⁸
Th us, a “fl ight simulator” concept emerges where one
may be able to simulate, practice, and perform the op-
eration without a patient. Already, eff ective curricula
for training teams in robotic surgery exist.⁴⁹
Robotic cardiac surgery is an evolutionary pro-
cess, and even the greatest skeptics must concede that
progress has been made. Surgical scientists must con-
tinue to evaluate this technology critically in this new
era of cardiac surgery. Despite enthusiasm, caution
cannot be overemphasized. Surgeons must be careful,
because indices of operative safety, speed of recovery,
level of discomfort, procedural cost, and long-term
operative quality have yet to be defi ned. Traditional
cardiac operations still enjoy long-term success with
ever-decreasing morbidity and mortality, and thus
remain our measure for comparison.
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