Aortic Valve Replacement after Previous Coronary Artery
4
INTRODUCTION Recently, acceptable results have been reported for aortic valve replacement (AVR) after previous coro- nary artery bypass grafting (CABG); however, the procedure remains challenging [1], particularly in patients with patent bypass grafts (PBGs), where there is a 5% incidence of injury to the internal tho- racic artery (ITA) [2,3]. The presence of PBGs is asso- ciated with specific risks of graft injuries and insuffi- cient myocardial protection; the dissection required to clamp the PBGs increases the potential risk of graft injuries, although clamping the PBGs ensures myo- cardial protection. Accordingly, an alternative strat- egy that leaves the ITA graft undissected and unclamped has been applied [2-5]. In addition, the therapeutic planning, including graft design during the previous CABG [6] and preoperative computed tomography (CT) [7-9], has also been reported. For patients undergoing AVR after previous CABG who have PBGs, it is important to have a meticulous sur- gical strategy to minimize specific risks. We report on the surgical management of patients undergoing AVR after previous CABG. CASE REPORT A 71-year-old man was referred to our hospital for a 3-month history of chest pressure on exertion. He had undergone CABG of the left ITA to the left ante- rior descending artery, the right ITA via the transverse sinus to the posterolateral branch of the left circumflex Kurume Medical Journal, 60, 29-32, 2013 Summary: We experienced a case of aortic valve replacement after previous coronary artery bypass grafting with patent bypass grafts. Based on the retrosternal anatomy assessed by preoperative angiography and thoracic computed tomography, aortic valve replacement was performed through a median resternotomy. After careful dissection of the right side of the heart and the ascending aorta, cardiopulmonary bypass was established with can- nulation of the ascending aorta and bicaval venous cannulation. The patent bypass grafts were dissected only as required for clamping and were clamped during cardiac arrest. After aortic valve replacement, the patient was uneventfully weaned from cardiopulmonary bypass and had a good postoperative recovery. It is important that surgeons have a meticulous strategy for reducing the risks associated with operating on patients with patent bypass grafts. We report on the surgical management of patients undergoing aortic valve replacement after pre- vious coronary artery bypass grafting, including careful planning during the first operation. Key words aortic valve replacement, coronary artery bypass grafting, patent bypass grafts Aortic Valve Replacement after Previous Coronary Artery Bypass Grafting: A Case Report SHIGEMITSU SUZUKI, KATSUHIKO NAKAMURA, KAZUMI TAKAGI * , HIDEYUKI KASHIKIE AND KEIICHI AKAIWA Division of Cardiovascular Surgery, Cardiovascular Center, Omura Municipal Hospital, Omura 856-8561, * Department of Surgery, Kurume University School of Medicine, Kurume 830-0011, Japan Received 13 December 2012, accepted 28 February 2013 J-STAGE advance publication 22 July 2013 Edited by TAKAFUMI UENO Address for correspondence: Shigemitsu Suzuki, MD, Division of Cardiovascular Surgery, Cardiovascular Center, Omura Municipal Hospital, 133-22 Kogashima-machi, Omura 856-8561, Japan. Tel: +81-957-52-2161 Fax: +81-957-52-8931 E-mail: [email protected]Abbreviations: AS, aortic valve stenosis; AVR, aortic valve replacement; CABG, coronary artery bypass grafting; CPB, cardiopulmonary bypass; CT, com- puted tomography; ITA, internal thoracic artery; MDCT, multidetector computed tomography; PBGs, patent bypass grafts; PPG, peak pressure gradient. Case Report
Aortic Valve Replacement after Previous Coronary Artery
INTRODUCTION
Recently, acceptable results have been reported for aortic valve
replacement (AVR) after previous coro- nary artery bypass grafting
(CABG); however, the procedure remains challenging [1],
particularly in patients with patent bypass grafts (PBGs), where
there is a 5% incidence of injury to the internal tho- racic artery
(ITA) [2,3]. The presence of PBGs is asso- ciated with specific
risks of graft injuries and insuffi- cient myocardial protection;
the dissection required to clamp the PBGs increases the potential
risk of graft injuries, although clamping the PBGs ensures myo-
cardial protection. Accordingly, an alternative strat- egy that
leaves the ITA graft undissected and unclamped has been applied
[2-5]. In addition, the
therapeutic planning, including graft design during the previous
CABG [6] and preoperative computed tomography (CT) [7-9], has also
been reported. For patients undergoing AVR after previous CABG who
have PBGs, it is important to have a meticulous sur- gical strategy
to minimize specific risks. We report on the surgical management of
patients undergoing AVR after previous CABG.
CASE REPORT
A 71-year-old man was referred to our hospital for a 3-month
history of chest pressure on exertion. He had undergone CABG of the
left ITA to the left ante- rior descending artery, the right ITA
via the transverse sinus to the posterolateral branch of the left
circumflex
Kurume Medical Journal, 60, 29-32, 2013
Summary: We experienced a case of aortic valve replacement after
previous coronary artery bypass grafting with patent bypass grafts.
Based on the retrosternal anatomy assessed by preoperative
angiography and thoracic computed tomography, aortic valve
replacement was performed through a median resternotomy. After
careful dissection of the right side of the heart and the ascending
aorta, cardiopulmonary bypass was established with can- nulation of
the ascending aorta and bicaval venous cannulation. The patent
bypass grafts were dissected only as required for clamping and were
clamped during cardiac arrest. After aortic valve replacement, the
patient was uneventfully weaned from cardiopulmonary bypass and had
a good postoperative recovery. It is important that surgeons have a
meticulous strategy for reducing the risks associated with
operating on patients with patent bypass grafts. We report on the
surgical management of patients undergoing aortic valve replacement
after pre- vious coronary artery bypass grafting, including careful
planning during the first operation. Key words aortic valve
replacement, coronary artery bypass grafting, patent bypass
grafts
Aortic Valve Replacement after Previous Coronary Artery Bypass
Grafting: A Case Report
SHIGEMITSU SUZUKI, KATSUHIKO NAKAMURA, KAZUMI TAKAGI, HIDEYUKI
KASHIKIE AND KEIICHI AKAIWA
Division of Cardiovascular Surgery, Cardiovascular Center, Omura
Municipal Hospital, Omura 856-8561, *Department of Surgery, Kurume
University School of Medicine, Kurume 830-0011, Japan
Received 13 December 2012, accepted 28 February 2013 J-STAGE
advance publication 22 July 2013
Edited by TAKAFUMI UENO
Abbreviations: AS, aortic valve stenosis; AVR, aortic valve
replacement; CABG, coronary artery bypass grafting; CPB,
cardiopulmonary bypass; CT, com- puted tomography; ITA, internal
thoracic artery; MDCT, multidetector computed tomography; PBGs,
patent bypass grafts; PPG, peak pressure gradient.
Case Report
Kurume Medical Journal Vol. 60, No. 1, 2013
artery, and the right gastroepiploic artery to the right posterior
descending branch of the right coronary ar- tery for angina
pectoris 9 years previously. In addition, mild aortic valve
stenosis (AS) with highly echogenic leaflets and a transvalvular
peak pressure gradient (PPG) of 26.0 mmHg had also been observed on
tran- sthoracic echocardiography. Angiography to investi- gate his
symptoms of chest pressure on exertion showed triple-vessel disease
of the native coronary arteries, all of which had PBGs (Fig. 1).
Cardiac catheterization showed an increased PPG across the aortic
valve of 47.0 mmHg. Consequently, we decided to perform AVR to
treat the deterioration of his AS.
Two months after discharge, he was readmitted for AVR, but
complained of shortness of breath on exer- tion. On physical
examination, a systolic and diastolic grade 2 murmur was audible at
the left sternal border in the third intercostal space. Chest X-ray
showed car- diomegaly with a cardiothoracic ratio of 58.0% and mild
pulmonary congestion. Transthoracic echocardi- ography showed
severe AS with a PPG of 85.4 mmHg. After treatment for congestive
heart failure, preopera- tive thoracic CT was performed, showing a
safe space between the ascending aorta and the sternum and prox-
imity of the right ventricle free wall to the sternum (Fig.
2).
AVR was performed through a median resternot- omy, paying close
attention to prevent injury to the mediastinal structures. After
careful dissection of the adhesions around the right side of the
heart and the ascending aorta, cardiopulmonary bypass (CPB) was
established with cannulation of the ascending aorta and bicaval
venous cannulation. The PBGs were dissected only as required for
clamping. After the initiation of total CPB, a right atriotomy was
performed and a cor- onary sinus cardioplegic catheter was
introduced for retrograde cardioplegia. The ascending aorta was
care- fully cross-clamped while avoiding injury to the right ITA.
Cardiac arrest was achieved by retrograde cold blood cardioplegia
with clamping of the PBGs. After a transverse aortotomy, the aortic
valve was exposed. All three cusps of the valve were thickened with
fused commissures that limited their excursion. A 21-mm
bioprosthesis was implanted in the supra-annular posi- tion with
pledgeted mattress sutures. The patient was uneventfully weaned
from the CPB. The durations of the operation, CPB, and aortic
cross-clamping were 723, 294, and 175 min, respectively.
The patient was treated for a superficial postopera- tive sternal
wound infection and discharged on the 46th postoperative day. Five
years after surgery, the patient is doing well.
30
Fig. 1. Preoperative angiography showing good patency of all in
situ arterial grafts in the first operation (A, B, and C). (B) The
right internal thoracic artery (arrow) was placed through the
transverse sinus and grafted to the posterolateral branch of the
left circumflex artery (arrowhead).
LITA, left internal thoracic artery; LAD, left anterior descending
artery; RITA, right internal thoracic artery; PL, posterolateral
branch; LCx, left circumflex artery; RGEA, right gastroepiploic
artery; PD, posterior descend- ing branch; RCA, right coronary
artery
(A)
(B)
(C)
31
AVR AFTER PREVIOUS CABG
DISCUSSION
The presence of PBGs in patients undergoing AVR after previous CABG
is associated with risks of graft injuries and insufficient
myocardial protection. Con- sequently, surgeons make particular
efforts to reduce these specific risks.
To our knowledge, the most common surgical pro- cedure in this
situation involves median resternotomy and clamping of the PBGs.
The advantage of clamping the PBGs is that regional myocardial
rewarming and cardioplegia ‘‘wash-out’’ near the PBGs during cardi-
oplegic arrest are avoided, which ensures myocardial protection.
However, the dissection required to clamp the PBGs increases the
potential risk of graft injuries. Some authors [2-5] have reported
on the efficacy of an alternative strategy that leaves the ITA
graft undissected and unclamped. Fujita et al. [5] recently
confirmed that their surgical strategy of leaving the patent ITA
grafts undissected was of benefit with regard to the postoperative
peak creatine kinase-MB level, ST changes seen on the
electrocardiogram, and new asyn- ergy seen on the echocardiogram. A
surgical strategy to eliminate dissection for PBG clamping would be
widely accepted and could induce favorable outcomes in
future.
Nevertheless, in patients with a patent right ITA crossing the
midline, as in our case, surgeons dissect the bypass graft from the
aorta to enable aortotomy for AVR. Therefore, it is indispensable
for a favorable out-
come that surgeons are aware of not only the route of the PBGs, but
also the relationship between the PBGs and mediastinal structures.
Preoperative CT has been reported to be of benefit in patients
undergoing cardiac reoperations [7,8]. In recent years,
multidetector CT (MDCT) has emerged as a highly reliable modality
for the comprehensive assessment of mediastinal and by- pass graft
anatomy, and it is routinely performed dur- ing preoperative
planning [8]. For patients undergoing cardiac reoperations, we have
also routinely performed preoperative thoracic CT, but not always
MDCT be- cause earlier-generation MDCT was often discouraged owing
to induction of bradycardia with β-blockers. Fortunately, a safe
space was observed between the ascending aorta and the sternum on
preoperative tho- racic CT in the present case. Moreover, the
informa- tion obtained from preoperative angiography (Fig. 1b) and
the previous operation report indicated that the right ITA had been
passed behind the ascending aorta. Consequently, we were able to
perform an aortotomy for AVR without injuring the patent right ITA;
how- ever, preoperative MDCT would have helped in plan- ning the
surgical approach.
With the improved long-term survival of CABG, we occasionally
encounter patients who require AVR after previous CABG. Most of
these patients were di- agnosed with mild or moderate AS at the
time of the previous CABG. The management of patients with mild or
moderate AS at the time of CABG remains com- plex: patients with
untreated AS may require AVR at a
Fig. 2. (A) Axial view of preoperative thoracic computed tomography
(CT) scan showing the safe space between the ascending aorta and
the sternum.
AA, ascending aorta; DA, descending aorta; PA, pulmonary artery;
ST, sternum; LL, left lung; RL, right lung
(B) Axial view of preoperative thoracic CT scan showing the
proximity of the right ventricular wall to the underside of the
sternum.
RV, right ventricle
Kurume Medical Journal Vol. 60, No. 1, 2013
later time, and those who underwent AVR will be ex- posed to risks
associated with prosthetic valves, such as endocarditis and
bioprosthetic valve degeneration [1,10]. For these patients,
surgeons should therefore plan their surgical procedure to enable
future aortot- omy for AVR at the time of CABG. Sugita et al. [6]
reported a case in which the proximal anastomoses were attached in
a more distal position of the ascend- ing aorta than usual. In our
case, we planned the CABG procedure using only in situ arterial
grafts with the po- sition of the right ITA behind the ascending
aorta and could more easily perform the AVR after previous CABG.
Meticulous surgical planning can play an im- portant role in the
ease of any future AVR operation.
CONCLUSION
In patients undergoing AVR after previous CABG who have PBGs, MDCT
helps to define the anatomy of the PBGs and their relationships
with other medias- tinal structures, and this is useful in planning
the AVR procedure to achieve a favorable outcome. If surgeons
carefully plan the CABG procedure, keeping in mind the possibility
of a future aortotomy for AVR, the AVR procedure can be performed
more easily.
DISCLOSURE STATEMENT
The authors declare no conflicts of interest associ- ated with this
study.
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