19 декабря 2001 00:00 |
Posterior Thoracotomy for Reoperative Coronary Artery Bypass
ABSTRACT
Background: This retrospective study evaluates morbidity and
mortality of reoperative coronary artery bypass grafting (CABG)
without cardiopulmonary bypass (CPB) using a posterior thoracotomy
to revascularize the lateral aspect of the heart.
Methods: From January 1995 to July 1999, reoperative CABG without
CPB was performed on 67 selected patients using a left posterior
thoracotomy approach. Preoperative risk factors, postoperative
mortality, and major complications were derived from the New York
State database.
Results: All patients were operated on without CPB. A total of 1.3
grafts per patient were performed. Freedom from major complications
was 95.5%. There were no postoperative cerebro-vascular accidents
(CVA) or new neurological deficits. Two patients (3%) had a
perioperative acute myocardial infarction. The actual mortality rate
was 4.5% (3/67), the expected mortality was 5.1% and the calculated
risk adjusted mortality was 2.1%.
Conclusions: Reoperative CABG without CPB to revascularize selected
coronary artery targets can be safely performed using a posterior
thoracotomy approach.
INTRODUCTION
Alternative surgical strategies have evolved over the last few years
to decrease the risks of reoperative CABG. Use of different surgical
incisions to avoid sternal reentry [Knight 1987, Grandjbakhch 1989,
Grosner 1990], minimization of graft and aortic manipulation to
decrease the possibility of embolism («no-touch» technique) [Savage
1994], and amelioration of the methods of myocardial protection to
limit the ischemic damage [Buckberg 1989] have all been included in
the surgical armamentarium of reoperative CABG. Avoidance of CPB has
been recently introduced and added as a strategy to limit the
invasiveness of primary CABG [Calafiore 1996, Bergsland 1998] and
its advantages have been particularly emphasized in patients at high
risk for conventional CABG [D'Ancona 1999b]. This technique has been
proposed as a safe alternative in reoperations, especially when
associated with alternative surgical approaches to revascularize
target areas of myocardium [Grandjean 1996, Akhter 1997, Boonstra
1997, Fonger 1997]. We herein report our experience with off-CPB
reoperative CABG using a left postero-lateral thoracotomy to
revascularize the lateral aspect of the myocardium.
MATERIALS AND METHODS
Reoperative CABG without CPB via a left posterior thoracotomy was
performed on 67 selected patients from January 1995 to July 1999.
This surgical approach was adopted in cases of recurrent coronary
artery disease (CAD) limited to the lateral wall of the heart.
Surgical technique
We started to use this approach for reoperative CABG in 1971
utilizing femoral cannulation for CPB [Grosner 1990]. In the last
several years, CPB has been avoided in the majority of cases. After
induction with general anesthesia and double lumen endotracheal
intubation, the patient was positioned for a standard left
posterolateral thoracotomy. An incision was then made 4 cm below the
tip of the scapula towards the left mid-axillary line and was
extended posteriorly towards the spine. The chest was entered
through the 6th intercostal space after dividing the latissimus
dorsi muscle and opening the thoracic fascia. The left lung was
collapsed and the pericardium was opened posterior to the phrenic
nerve. This exposure provided access to all obtuse marginal (OM)
branches of the circumflex system and posterolateral coronary artery
(PLA) branches.
After analysis of the adhesions, the target site had been selected
on either the native coronary or the hood of an old graft.
Intravenous heparin was administered. The coronary stabilizer
platform (CTS; Cupertino, CA) was positioned and proximal snaring of
the coronary artery was achieved with a 4−0 Prolene® pledgetted
suture. After 3 minutes of ischemic preconditioning, the target
vessel was opened. An appropriate size intracoronary shunt was
placed within the vessel and the snare was released to prevent
further myocardial ischemia. Distal anastomoses were performed with
7−0 Prolene® running suture using a blower-aerosolizer to improve
visibility during the procedure. The graft was then anastomosed
proximally to the partially clamped descending thoracic aorta.
Transit time flow measurement (TTFM) was used to confirm graft
patency. Flow curves and flow values were recorded in the flowmeter
hardware (Medistim Butterfly; Medistim, Oslo, Norway).
If combined revascularization of the left anterior descending (LAD)
and circumflex coronary artery territory was needed, the incision
was extended anteriorly, gaining access to the anterior aspect of
the heart. In this case harvesting of the left internal mammary
artery, whenever available, was performed, and the conduit was used
to revascularize either the LAD or the OM branches.
Data collection and statistical analysis
All data regarding this group of patients were entered in the New
York State Database and retrospectively analyzed. Operative priority
was defined as emergent when severity and distribution of CAD, along
with hemodynamic instability, mandated immediate surgery.
In regard to perioperative outcomes, perioperative stroke was
defined as any new neurologic event lasting more than 24 hours after
the operation. Perioperative acute myocardial infarction (AMI) was
defined as an abnormal elevation of cardiac enzymes (CK-MB,
failure was defined as the need for ventilatory support for 48 hours
or more, postoperatively. The absence of any postoperative
complication was referred to as «freedom from complications». Actual
mortality was defined as in-hospital within 30 days from the
operation. Expected mortality rate reflected preoperative risk
factors. Risk-adjusted mortality rate was calculated by dividing the
actual mortality by the expected mortality and multiplying the
result by the New York State mortality rate.
RESULTS
Demographic data are summarized in Table 1. Mean age was 65.4 years
(range: 47−80 years). There were 60 males (89.6%) and 7 females
(10.4%). All patients had undergone at least one operation for CAD,
6 patients (9%) had already been operated on twice and two patients
(3%) three times. A total of 1.3 grafts per patient were performed.
Data regarding the type of conduits used and the target coronary
arteries are summarized in Table 2.
There were no conversions to CPB or to median sternotomy. Mortality
and morbidity rates are reported in Table 3. No strokes or
postoperative neurological deficits were reported. Two patients (3%)
developed a postoperative AMI. Freedom from complications was 95.5%.
Average hospitalization after surgery was 8 days. Actual mortality
was 4.5% (3/67), expected mortality was 5.1% and risk-adjusted
mortality was 2.1%. Two patients (3%) died from left ventricular
failure and in one case (1.5%) respiratory failure occurred
accompanied by acute pancreatitis and sepsis. Intraoperative TTFM
was adopted to document patency in 43 grafts. Flows were measured
with and without proximal snaring of the native coronary artery and
all grafts tested were patent by TTFM.
DISCUSSION
The referral pattern for CABG has been changing including an
increasing number of high-risk patients. In this regard, it has been
estimated that 17% of the patients, previously submitted for CABG,
deleterious complications of reoperative CABG, attention has been
focused on alternative surgical strategies aimed at improving
myocardial protection and at reducing manipulation of the heart,
aorta, and old grafts. Appropriate use of antegrade and retrograde
cardioplegia in re-operations has, for example, been shown to reduce
mortality to levels as low as 3.4% [Lytle 1987]. Similarly, the use
of a variety of surgical techniques, such as «no-touch» dissection
and single aortic cross-clamping, has been shown to decrease
operative mortality [Salerno 1982, Savage 1994].
Although the above-mentioned techniques have decreased the risks of
reoperative CABG, the complications related to the use of CPB are
still present, especially whenever long perfusion periods are
required during reoperations. Long CPB time has been identified as
the most powerful independent predictor of mortality after
reoperative CABG [He 1995]. In this regard, avoidance of CPB may be
proposed as a valuable alternative to treat recurrent CAD.
To further contain the risks of this already highly compromised
population, use of alternative surgical approaches can be suggested
to revascularize, off-CPB, limited areas of the myocardium avoiding
the hazards of resternotomy and limiting manipulation on the
ascending aorta, heart, and old grafts. Different approaches have
been proposed to achieve an off-CPB revascularization of target
coronary artery branches in the setting of reoperative CABG.
Boonstra et al. [Boonstra 1997] first suggested the use of a left
anterior small thoracotomy (LAST) with anastomosis of the left
internal mammary artery (LIMA) to the LAD to treat recurrent CAD
involving the LAD. Grandjean et al. proposed a subxiphoid approach
with harvesting of the right gastroepiploic artery (RGEA) to reach,
Revascularization of recurrent isolated lesions of the circumflex
system can be achieved via a left postero-lateral thoracotomy. This
approach was first performed using the femoral vessels for
institution of CPB [Knight 1987, Grandjbakhch 1989, Grosner 1990],
and only later the same conceptual framework was adopted without CPB
[Fonger 1997, Baumgartner 1999].
Even if the advantages offered by these alternative surgical
approaches seem to be intuitively evident, there is still a limited
number of comparative studies with traditional reoperative coronary
artery surgery. Miyaji et al. [Miyaji 1999] demonstrated similar
results between primary and reoperative CABG performed off-CPB.
Allen et al. [Allen 1997] showed a significant decrease in the rate
of atrial fibrillation, number of transfusions and ICU length of
stay when comparing a group of patients reoperated upon via LAST
with a group of conventional redo operations with disease limited to
the LAD.
Absence of strokes, low rate of periopeartive AMI (3%) and high rate
of freedom from complications (95.5%), have been reported in our
experience with reoperative CABG off-CPB via left thoracotomy. These
results are very encouraging and are similar to those proposed for
larger groups operated on with conventional CPB and via median
sternotomy [Lytle 1987, Loop 1990, Aranki 1994, Savage 1994].
Operative mortality in reoperative CABG varies between 3.4% and
12.5% with a median of 8% [He 1995]. In our experience, a rate of
4.5% reflects the results published by other authors using
conventional surgical techniques on CPB [Lytle 1987, Loop 1990,
Aranki 1994, Savage 1994, He 1995].
The feasibility of reoperative CABG off-pump via median sternotomy
is not well documented, and exposure of the lateral coronary artery
branches, i.e. circumflex system, can be troublesome if meticulous
lysis of the pericardial adhesions is not performed before using the
modern techniques of elevation and stabilization of the heart.
Revascularization of the lateral vessels of the heart without CPB
through median sternotomy has been made easier since the
introduction of the «single suture» technique in the oblique sinus
of the pericardium [Karamanoukian 1999] in conjunction with modern
stabilization systems. Despite that, a posterior-thoracotomy
approach can result in better and safer coronary exposure in
patients with recurrent CAD, extended and limited to the circumflex
coronary system.
In our experience a total number of 1.3 grafts per patient, as above
reported, appears to be very reductive. It has to be emphasized that
all patients referred for this procedure had limited CAD localized
to the lateral aspect of the heart and complete myocardial
revascularization was performed in all cases.
Lack of clinical and angiographic follow-up is an important
limitation of our study and, for this reason we have limited our
discussion to the intraoperative and perioperative results. Partial
documentation of intraoperative graft patency was obtained via TTFMs
in 41 grafts. This technology has been demonstrated to be
particularly useful to detect, and eventually correct, critical
anastomotic lesions [Cerrito 1999, D'Ancona 1999a, D'Ancona (in
press)].
In conclusion, our results indicate that reoperative CABG for CAD,
extended and limited to the circumflex system, can be safely
performed via a left posterior thoracotomy without CPB, limiting
postoperative morbidity and mortality. Extensive dissection and
manipulation of the heart and old grafts can be avoided thereby
minimizing the risks for embolism and achieving revascularization of
culprit coronary lesions. Median sternotomy or other surgical
approaches should be, on the contrary, performed if the CAD is not
limited to the circumflex system aiming always to a complete
myocardial revascularization. Acquisition of enough confidence with
the modern techniques of coronary exposure, stabilization and
shunting, as used during primary operations off-CPB, is mandatory
before performing this operation as a redo. Clinical and
angiographic follow-up in prospective randomized studies are
necessary to better define limits and indications of this very
promising technique.
REVIEW AND COMMENTARY
1. Editorial Board Member L023 writes:
This is a nicely written paper, with a sufficient number of
patients, albeit without medium or long-term follow-up of an
approach to redo revascularization.
a) The author should comment on whether all patients had «total
revascularization» redo surgery or only major target vessels
revascularized with this approach. Their indications for selecting
this approach should also be more fully discussed.
b) Their statistics in terms of the % number of redo cases that this
cohort formed would also be of interest, as the number of redo cases
approached by other minimally invasive/off-pump approaches.
Author(s)' Response by Giuseppe D'Ancona, MD:
a) All patients had complete myocardial revascularization. Coronary
artery branches that at angiography were determined to have very
poor quality and to be bad surgical targets were not revascularized.
This approach was chosen only for patients with coronary artery
disease limited to the marginal branches. If other coronaries were
amenable to surgical treatment, a median sternotomy was preferred.
b) In the same period of time a total of 274 patients underwent
reoperative CABG off-CPB and 307 on-CPB. In the off-CPB group, 122
patients had a median sternotomy (44.5%), and the remaining patients
were treated with alternative surgical approaches (posterior
thoracotomy, LAST-RAST, subxiphoid with RGEA). More specific data
can not be disclosed and has already been submitted for publication.
2. Editorial Board Member EE455 writes:
The lateral thoracotomy approach should become standard for this
peculiar and marginal group of patients presented with isolated
lateral lesions and patent grafts or native vessels on the anterior
and inferior walls.
a) The operative results are not reported. Neither the graft
patency, which is discussed by the authors, nor the effects on
angina recurrence.
b)The authors assess that this approach is feasible with results as
good as those provided by median sternotomy. In my experience, the
PT approach is much easier technically, thus faster than sternotomy.
It requires less dissection of the pericardial adhesions and less
blood loss are to be expected in this very marginal group of
patients. I think the advantages should be stressed.
c) We have combined this approach with TMLR on the anterior aspect
of the heart in four cases. Do the authors have an opinion on this
type of hybrid approach, which increases the potential indications
to patients with antero-lateral viability not due to complete
classical revascularization?
d) Conversion to sternotomy, which has not happened in the cohort,
would be very difficult in this position. In case of emergency, CPB
should be instituted through a groin incision, thus mandating a
preoperative assessment of the ilio femoral vasculature. This point
might be highlighted.
Author(s)' Response by Giuseppe D'Ancona, MD:
a) As already specified by the title («perioperative results») and
discussed in the manuscript, we are perfectly conscious of the
limitations of the study and the lack of angiographic and clinical
follow-up.
b) It is obvious that avoidance of resternotomy can decrease the
risks of injury on vital structures and reduce manipulation of the
heart, old grafts and large vessels. On the other hand, the PT
approach can be extremely difficult and adequate exposure and
stabilization of the coronary targets can be very troublesome. We
suggest adopting this approach only after having acquired enough
experience with off-CPB primary operations.
c) We do not have experience with TMLR and the clinical
applicability of this technology is still very controversial.
d) Conversion to sternotomy is almost always not necessary and
femoral vessels can be cannulated for CPB. We do not routinely
perform perioperative assessment of the groin vessels. This is a
very good point, probably applicable to all reoperative CABG
patients.
3. Editorial Board Member EK34 writes:
This is a nice relatively large series of a highly selected group.
The data should be a gold-standard for this patient group. The
author must use the STS definition of mortality [~] «all deaths
occurring during the hospitalization in which the operation was
performed. Those deaths occurring after hospitalization but within
30 days of the procedure….Those deaths occurring after 30 days
that are clearly related to the surgical procedure will also be
counted as operative mortality».
Author(s)' Response by Giuseppe D'Ancona, MD:
We have not yet reviewed our follow-up data for this group of
patients. We can only consider the in-hospital mortality and, for
this reason, the STS definition of mortality is not applicable in
this particular case.
4. Editorial Board Member AR11 writes:
The authors need to detail the information on their patient group
(from how big an overall group of revascularization patients were
they selected; 67 patients in a 4.5 year interval doesn't sound like
very many). Comparison data to other reops in their institution
might be helpful, and certainly interesting, for the reader.
Author(s)' Response by Giuseppe D'Ancona, MD:
A total of 274 patients underwent off-CPB reoperative CABG in the
same period of time. Different surgical approaches were used on the
basis of the extension of the coronary artery disease. A total of
307 patients were reoperated on using CPB. A lower incidence of
postoperative CVA was recorded in the off-CPB group together with a
higher rate of freedom from major complications. More extensive data
have been submitted for publication and can not be discussed.
5. Editorial Board Member MN93 writes:
This is an innovative approach for re-op surgery where access to the
descending thoracic aorta is required. A more anterior approach,
Author(s)' Response by Giuseppe D'Ancona, MD:
A more anterior incision facilitates harvesting of the LIMA. In this
case, revascularization of the circumflex territory with the
pedicled LIMA can be achieved only after having extended the
incision posteriorly to gain adequate surgical exposure.
AUTHOR/ARTICLE INFORMATION
Reprint requests to: Hratch Karamanoukian, MD, Kaleida
Health–Buffalo General Hospital Site, 100 High Street, Buffalo, New
York 14203; Phone: (716) 859−1080, Fax: (716) 859−4687
Submitted on: February 15, 2000; Accepted on: February 16, 2000
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