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33
Personal perspectives onthe early
development ofinternal thoracic artery
graing and therole ofbilateral internal
thoracic arterygraing
George E. Green and Bruce W. Lytle
Fifty years ofinternal thoracic artery
grafting (George E.Green)
Full appreciation of the history of internal thoracic artery (ITA)
graing requires recognition of the persistent work of Arthur
Vineberg (1903– 1988). Based on his studies of myocardial anatomy,
Vineberg believed that implantation of the bleeding ITA into heart
muscle would create a new collateral blood supply to the heart. He
chose the ITA because his studies had convinced him that it rarely
was aected by atherosclerosis. His experimental work in dogs
began in 1945. He supported his contention by postmortem injections of radio- opaque medium into the implanted ITAs. On some
occasions the opaque medium was visualized in distal coronary
arterial segments. Connections to these arterial segments were arteriolar (0.001mm). Vineberg’s critics considered the postmortem
arteriographic ndings to be pressure artefacts.
In 1958, Mason Sones (1919– 1985), newly appointed to the
Cleveland Clinic, discovered and then rened the technique
of selective coronary arteriography. In 1962, Sones selectively
opacied ITAs implanted by the Vineberg technique. Most were
patent. A few communicated with distal coronary segments.
Sones and the cardiac surgical department directed by Donald
B.Eer broadened the study to determine by pre- and postoperative angiography which patients would benet from ITA implants. By 1965, analysis of the data conrmed that most implants
were patent but in only about 30% of patients were distal coronary
arterial segments also visualized. e unvisualized connections
were arteriolar (0.001mm). Patients who did benet had collateral connections (arteriolar) to distal coronary segments prior to
operation. ITA implants increased this collateral circulation. e
time required for new circulation ranged from weeks to 3months.
Eer was invited by the American Heart Association to present
these data at its annual convention, which was held in 1965 in
Miami, Florida.
I was attending that meeting to present data conrming
Jacobson’s contention that with the high magnication of the
surgical microscope blood vessels of 1 mm in diameter could
be anastomosed with consistent success. My surgical interest at
that time was using the technique to revascularize free gras of
jejunum transposed to the neck to replace segments of cervical
oesophagus. Listening to Eer describe communications (arteriolar) which could develop between the implanted ITA and distal
coronary branches Ithought of anastomosing the ITA directly to a
distal coronary segment. Iwas sure that using the surgical microscope the ITA could be anastomosed to a distal coronary segment
1mm in diameter.
ITA– coronary artery anastomosis was rst reported from the experimental laboratory in 1956. It was repeated by many surgeons in
many laboratories with many techniques and in 1964 was reported
in conjunction with the use of the heart– lung machine. All these
demonstrations were anastomoses of the ITA to proximal coronary
segments, approximately 3 mm in diameter. Misunderstanding
statements about the proximal location of coronary occlusions may
have led to this perseverative work. Although major occlusions usually were proximal, atherosclerotic thickening extended well beyond
them. ese thickenings were the basis of Szilagyi’s warning that bypass surgery would require anastomosis to vessels 2mm or less in
diameter.
In 1965 Ibegan a project of ITA anastomosis to 1mm distal le
anterior descending artery (LAD) segments. e project included
proximal LAD ligation, blood ow measurement early and late aer
anastomosis, and late postoperative (8months) cineangiography.
e success of these experiments brought me to grips with clinical
application. Despite the fact that Ihad conducted the work in the
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surgical laboratory of NewYork University, permission for clinical application at NewYork University was denied in September
of 1967. e story of the search for a place for clinical application
illuminates surgical thinking of the time. ITA implantation had
become accepted and was performed in most university centres.
It was so rmly established that extensions of ITA implants were
attempted with implants of the intercostal artery, the right
gastroepiploic artery, and the splenic artery. By contrast, direct
microsuture anastomosis using the surgical microscope was not
considered clinically feasible. Most of my letters of inquiry went
unanswered, but there were some respondents. C.Walton Lillehei,
the dynamic pioneer of cardiac surgery, was encouraging but was
in the process of leaving the University of Minnesota to become
Chairman of the Department of Surgery at NewYork Hospital of
the Cornell Medical Center and wrote that he could not in transition sponsor any new projects. Adrian Kantrowitz thought the data
interesting but wanted the experiments repeated in his laboratory.
At Sones’ urging, Donald Eer invited me to show him the postoperative cineangiograms; Dr Eer was impressed and favoured
clinical application at the Cleveland Clinic, but wanted me to do
so as his resident. Michael DeBakey did not reply to the letter but
during one of his visits to NewYork City an introduction was arranged. He listened closely to my proposal. His reply was denitive:clinical application was impossible, coronary bypass surgery
was not feasible.
Two random events suddenly opened the way for clinical application of ITA– LAD anastomosis. First, the explosive impact of heart
transplantation reported in December of 1967 made other cardiac
procedures seem minor by comparison. en, in December of 1967,
e Journal of oracic and Cardiovascular Surgery published a report by the Russian surgeon Vladimir Kolessov of successful ITA–
LAD anastomosis in six patients.
Although the procedure had been prohibited at the NewYork
University Hospital, Dr David Tice, Director of Surgery at the afliated NewYork Veterans Administration Hospital, invited me to
do it there. Idid the rst ITA– LAD anastomosis in the United States
there in February of 1968., During that same month Bailey and
Hirose did the rst ITA suture anastomosis to right coronary using
the right ITA (RITA).
Although Sones had discovered coronary arteriography in
1958 and by 1968 had brought it to a very high point, few laboratories could match his capability. In the New York City
area, coronary arteriography could define proximal areas of
obstruction but rarely defined the status of the distal circulation. Postmortem studies had made it clear to me that although
severe areas of proximal atherosclerosis were prominent, other
areas extended well beyond the proximal obstruction in skiplike fashion. Placing a graft between two areas of stenosis
seemed less sensible than placement far distally beyond the
last atherosclerotic stenosis. My choice was placement of the
ITA graft to the distal third of the LAD, usually a normal thinwalled segment about 1.5mm in diameter. My expectation was
not to achieve normal myocardial perfusion but to augment
flow to the ischaemic myocardium. In 1968 Ioperated on 18
patients. Although all were desperately ill no operating room
fatalities occurred. Nevertheless, there were six early postoperative deaths. Postmortem examination showed patent ITA anastomoses but severe triple vessel disease.
In June of 1968, saphenous vein gra (SVG) to the right coronary
artery (RCA) was reported by Favaloro. I combined it with ITA
anastomosis to the LAD. Although Bailey and Hirose had described
RITA artery to right coronary anastomosis in 1968, Iwas reluctant
to use that procedure because the RCA is much larger than the ITA.
e size mismatch of small ITA to large RCA would cause turbulence of ow at the anastomosis. Ifeared this would make anastomotic stenosis likely. Skill in very high mobilization of the ITA and
routing it parallel to the phrenic nerve so that it could reach the posterior descending artery was to come later, as was the use of free ITA
gras arising from the aorta.
In 1969, Ibegan to perform anastomoses to the circumex artery,
and with the advent of triple bypasses the problem of early postoperative mortality was resolved. By 1969, several centres were
performing coronary bypass surgery. Most used only SVGs. Iwas
considered odd for persisting in the use of the ITA. Ipersisted because in my practice when angina recurred, angiography almost invariably showed SVG stenosis or occlusion to be the cause of the
recurrent angina. erefore, despite criticism Icontinued to use the
ITA on a routine basis for anastomosis to the LAD. By then several
other surgeons felt that ITA gras would prove to be preferable to
SVGs. Earle Kay felt so strongly that he initiated the use of both ITAs
as gras and reported a series in 1974.
At the urging of Mason Sones, Floyd Loop began to use the ITA
gra. To extend its use he introduced the free ITA gra, detached
from its subclavian origin and anastomosed to the ascending aorta.
is anastomosis was demanding because of the marked dierence
in thickness of the aorta and the ITA. Following the crowd, Loop
ignored the need for high magnication. To resolve this problem,
Hendrick Barner recommended anastomosing the ITA to the hood
of the vein gra and George Schimert recommended anastomosing it to a vein patch in the aorta. Because of the diculty of
handling the thin walled and friable ITA, Alain Carpentier introduced the radial artery (RA) free gra in 1973.
Even enthusiasts of arterial graing acknowledged that the ITA
was a far more demanding gra than the saphenous vein. As skilled
a surgeon as Favaloro wrote in 1970:
It is highly doubtful that full clinical application of this procedure will
reach a large scale:the anastomosis is extremely dicult to perform
mostly because of the fragile wall of the internal mammary artery ra-
ther than the coronary artery itself, and the limitation of the size of
the anastomosis by the caliber of the internal mammary artery in its
distal portion.
Favaloro’s statement highlights the dierence in technique required
for ITA gras as compared to the SVGs that he pioneered at the
Cleveland Clinic. Between 1976 and 1983 few surgeons used the ITA.
In 1970 Ile NewYork University to initiate the coronary surgery programme at St. Luke’s Hospital, NewYork. Simultaneously,
a clinical follow- up programme was initiated by Dr Airlie Cameron
of the Division of Cardiology. Soon thereaer, Dr Julio Sosa who
had worked with Sones during the development of coronary angiography, and who had participated in the rst angiographic studies
of ITA implants, expressed interest in referring patients to me for
ITA anastomosis and restudying them aer ITA anastomosis. e
restudies were not done arbitrarily. ey were done to evaluate recurrence of angina, recurrent myocardial infarction, or signs of ischaemia on electrocardiographic stress tests. Few restudies were
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performed prior to 1975. During the latter part of the decade restudies became more frequent. By 1981, Sosa had restudied 37
patients who had both ITA and SVGs. e mean time following operation was 7years. Analysis of the data was striking:94% of the
ITA gras were widely patent, 50% of the SVGs were occluded, and
50% of those patent showed atherosclerotic stenosis within the body
of the gra. In 1981, the data was submitted for presentation at the
annual meeting of the American Association for oracic Surgery.
It was not selected for presentation. Iwas persistent and submitted
the data again in 1982. e resubmission was selected, presented
in spring of 1983, and published later that year. By then, similar
angiographic studies had come from Montreal. In 1984, Grondin,
whose 1975 publication dampened enthusiasm for ITA gras,
reversed his position and became a champion of the procedure.
e use of sequential ITA gras was described by Tector in 1984
and John Pym described the use of the right gastropiploic artery for
anastomosis to the distal RCA in 1987.
In 1985, Cameron collated the 15- year follow- up data of the 748
patients operated at St. Luke’s Hospital between 1970 and 1973. ere
was a highly signicant advantage conferred to those patients who
had single ITA (SITA) anastomosis in combination with SVGs as
compared to those who had SVGs alone. ere was even further advantage to those patients who had bilateral ITA gras. e number
of patients having bilateral ITA anastomoses was too small to reach
statistical signicance but Ifound the trend compelling. Iwas eager
to understand why ITA gras fared so much better than SVGs.
One obvious dierence between the vein gra and the ITA gra
was that of nutrient vessels. All vasa vasorum were disrupted in the
process of removing a SVG from the leg. It was known to take many
weeks before nutrition of the wall of the vein gra was reconstituted.
is seemed a plausible explanation for the 10% of saphenous gras
Recognition of the superiority of the ITA gra created such a demand for its use that it became the standard gra to the all- important
LAD in many surgical practices. Because the ITA gra remains patent even if its anastomotic site to the LAD is stenotic, angiographic
scrutiny of the surgical result may not have been optimal, but it did
show ITA narrowings that were usually called ‘spasm’ limiting blood
ow and causing ‘hypoperfusion’. ‘Spasm’ may well have been late
stricture caused by damage to the ITA during mobilization or rupture
of the IEL by forceful dilatation (mechanical or hydrostatic) prior to
anastomosis. Such dilatation was advocated by many surgeons.
e small size of the ITA also posed problems to its mobilization
from the chest wall. Too oen, instead of meticulous mobilization
within 2mm of the ITA a broad pedicle was quickly mobilized
using high- intensity cautery. is le devitalized tissue on the chest
wall, impaired blood ow to the sternum, and may have been the
cause of high rates of postoperative sternal dehiscence and mediastinal infection reported by some surgeons.
e rst study that statistically demonstrated the clinical advantage of bilateral ITA gras was that of Earle Kay. It was based on
surgery performed in 1972 when mobilization of the ITA to its origin
from the subclavian artery and avoiding damage the nearby phrenic
nerve had not been perfected. Nor had proper routing of pedicle
gras to posterior areas of the heart. More dramatic advantage of
multiple ITA gras including free and sequential gras was published in 1994. It reported a consecutive series of 143 patients requiring multiple gras; 317 of the 441 anastomoses were constructed
from ITAs. Of the 143 patients, 103 had bilateral, 51 sequential, and
49 free ITAs gras. During 5years of follow- up, postoperative angina and myocardial infarction were signicantly more common in
those patients who had been operated with just one ITA compared
to those who received multiple ITA gras.
that suered early brotic occlusion, but the explanation for late atherosclerosis which aected the majority of SVGs was not apparent
until the publication of the work of Frank Sims (1921– 2013). Sims, a
pathologist, accepted the resistance of the ITA to atherosclerosis as a
known fact. Wanting to study the incidence and severity of coronary
atherosclerosis in residents of the Fiji Islands he used each subject’s
ITA as a standard of normality and then compared the intimal thickness of the coronary to that of the ITA, in age groups ranging from
the rst to the eighth decade. In so doing he noticed that the dening
boundary between the intima and the media, the internal elastic
lamina (IEL), was radically dierent in ITAs from that in the coronaries. e IEL of the ITA was usually dense and unbroken. e
IEL of the coronary was usually fragmented. Smooth muscle cells
migrated through gaps in the IEL and changed from a synthetic to
a hyperplastic mode in their new locale. He later showed that endothelium of ITAs was stable. Endothelium anchored to the IEL. When
the IEL was broken and discontinuous endothelial slough ensued.
He showed that all the arteries of domestic animals are similar to the
ITA. Human arteries are similar to the coronary. Human veins have
even more deciencies of IEL than human arteries.
Putting that knowledge into practice was relatively easy in 1985
because enthusiasm for arterial graing in both the cardiological
and cardiac surgical communities was growing. Synchronous with
Cameron’s (15- year) study from St. Luke’s in New York, a similar
(10- year) study from the Cleveland Clinic was published. Robert
Dion’s work on the broad application of bilateral and sequential
gras was published in 1989.
The role ofbilateral internal thoracic
artery grafting (Bruce W.Lytle)
Introduction
Following the study by Loop et al. published in 1986 that documented a survival advantage produced by the le ITA (LITA)– LAD
gra, it became a standard part of operations for coronary bypass
graing. Prior to the publication of those data, the LITA– LAD
gra was usually not used as part of revascularization operations
despite patency data that showed the superiority of ITA to SVGS.
Subsequently, many further observational, risk- adjusted studies
have appeared to conrm the survival benet of the LITA– LAD
gra, and today that part of the revascularization operation has
reached the status of a quality indicator in the performance of bypass
surgery, despite the lack of a large randomized trial conrming its
superiority. e LITA to LAD surgical strategy is used in over 95%
of bypass operations and is the only cardiac surgical technique, perhaps the only surgical technique of any kind, considered mandatory
during the performance of an operation.
From the dawn of the coronary bypass era, small numbers of bilateral ITA (BITA) gra operations were performed, oen when alternative conduits were not available or by scattered surgeons and
centres where the ITA concept was an article of faith. In 1980, we
reviewed patients undergoing multivessel coronary revascularization
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whose saphenous veins had previously been removed in order to
follow the outcomes of alternative bypass gras. We found that despite a high level of incomplete revascularization, this patient subset
did extremely well clinically, leading us to rethink our graing strategies and move in the direction of using BITA graing more oen in
elective situations. Perhaps it was the case that adding the benets
of a RITA gra to the LITA gra would further enhance the clinical eectiveness of bypass surgery operations. Aer all, the risk of
death produced by multivessel coronary disease exceeded that of
single- vessel LAD disease. Other groups had asked the same questions and had come to the same conclusion, thus leading to the alteration of clinical practice, use of BITA graing, and the creation of
clinical databases. ese advancements would allow the long- term
evaluation of the BITA strategy by Barner in St. Louis, Kurlansky
in Miami, and Tector in Milwaukee, among others, as well as the
Cleveland Clinic.– As time has passed, multiple non- randomized
studies have been conducted both in the United States and abroad,
involving single- centre, multicentre, state, national, and professional
databases. e heavy preponderance of data appears to indicate that
in heterogeneous groups of patients, the use of the BITA strategy produces superior long- term outcomes in terms of survival and avoidance of repeat revascularization when compared with a SITA strategy.
However, in contrast to the LITA– LAD gra, the BITA operation has
not become standard part of coronary bypass graing, being used
during approximately 4% of operations in the United States despite
the acknowledgement by most in the eld that the BITA approach
produces superior long- term outcomes. Even in operations performed for ‘good- risk’ patients, few centres use the BITA approach in
the majority of operations. In this part of the chapter, Iwill examine
current data involving outcomes, some technical aspects of BITA
graing, and some of the reasons it appears to be underutilized.
Outcomes ofBITAgrafting
Studies comparing BITA and SITA graing that have included
enough patients receiving BITA graing followed long enough to
be able to draw conclusions began to appear in the late 1990s and
continue to this day. No currently available studies with long- term
follow- up contain randomized cohorts but multiple methods of statistical adjustment have been used in attempts to mitigate selection
bias. Realistically, however, it must be assumed that patient and surgeon selection biases have played a role in the assignment of operation in all observational studies, and it cannot be assumed that
any statistical adjustments turn an observational study into a randomized trial. e skill, experience, commitment, and opinions of
the surgeons who are deciding which operation to perform do not
represent binary variables and have evolved over time, as has the
make- up of the population of patients undergoing bypass surgery. In
very few institutions of the many who have reported outcomes has
the proportion of patients undergoing bypass surgery and receiving
BITA gras ever exceeded, or even approached 50%, itself an indication of selection biases. It is also illogical to think that the outcomes
of the randomized trial now in progress will answer all questions.
In observational trials, bias occurs at the point of treatment selection; whereas, in randomized trials bias occurs at the point of inclusion of the patient into the trial. However, at this point there are
some general principles that can be gleaned from the mountain of
observation data that have been reported.
1. Patients undergoing BITA graing appear to have a superior
long- term survival rate to those having SITA operations. e
dierences in survival rate vary according to the make- up of the
patient sample but the hazard ratio for late death of the BITA patients centres around 0.8 for heterogeneous groups of patients in
studies with at least a 10- year follow- up interval. us, the incremental benet of BITA relative to SITA graing may be slightly
less and is recognizable aer longer follow- up than when SITA
graing is compared with an SVG- only strategy. Moreover, the
observation that a heterogeneous group of patients experiences
a survival advantage with BITA graing does not necessarily
mean that every single patient would be expected to experience a
survival advantage and much work has been dedicated to trying
to identify subgroups that do particularly well or particularly
poorly with BITA or SITA graing. In general, the longer the
life expectancy, based on age and comorbidities, the more the
advantage of BITA graing. However, reports have also documented the seeming advantage of this strategy in cohorts of elderly and diabetic patients.,
e survival advantage of BITA graing is assumed to be
based on the superior long- term patency of a second ITA gra
relative to an SVG, although because we do not have a means of
continuously establishing gra patency, that relationship is hard
to prove. In addition to multiple studies that establish favourable
long- term ITA gra patency, there are also data which suggest
that placing an ITA gra leads to less rapid and less consistent
native coronary occlusion, an eect that also may have a positive
impact on late survival.
2. BITA graing probably leads to a decreased rate of reinter vention.
e emergence of percutaneous coronary intervention as an alternative anatomical treatment for treatment of stenosis in bypass gras and native coronary arteries has made this issue more
dicult to study than it was in the days when reoperation was
the preferred strategy for most reinterventions. However, it is
certainly the observation that BITA graing decreases the likelihood of postoperative reoperation, in part because it is less frequently needed and perhaps in part because surgeons are less
likely to want to undertake it following a primary procedure that
includes BITA graing.
3. e operative mortality rate of BITA and SITA operations is
probably equivalent in the hands of surgeons equally experienced with both, considering that all surgeons employ judgement in matching patient and operation. Many surgeons
consider uncontrolled diabetes and severe obesity to be relative
contraindications to BITA graing, and the limited life expectancy of such patients may lessen the benet achieved. e differences in operative risk between SITA and BITA graing that
have been reported, statistically signicant or not, are probably
based on patient selection, and surgeon- related variables. BITA
graing is oen a technically more complex operation, and in
most studies increases operative time relative to SITA strategies,
but when applied with reasonable selective criteria does not appear to increase operative mortality.
4. When compared with SITA graing, BITA graing engenders
a higher risk of serious sternal complications. ose risks have
diminished with time, today hovering around 1%, and in many
modern studies the dierence is not statistically signicant, but
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there is a dierence between the SITA and BITA strategies. Use
of skeletonized ITA preparation, glucose control, and probably
patient selection have largely ameliorated this issue, but it remains the most real and salient disadvantage of BITA graing.
5. e determination of long- term gra patency is fraught with
potential inaccuracy for multiple reasons. We do not have a way
of continuously monitoring gra patency, so if an angiographic
study shows a gra to be occluded, we do not know precisely
when that occlusion occurred. Also, postoperative studies are
not routine today the way they were in the 1970s, so many fewer
patients are restudied, and they undergo restudy at less frequent
intervals. Unless a prospective angiographic trial is carried
out, a small proportion of operated patients are restudied and
most of those are thought to have symptoms. Only surviving
patients undergo postoperative angiography; however, some
‘broad strokes of the brush’ observations can be made. e
documented patency rate is the best for the in situ LITA– LAD
gra. Nothing is as good as that gra. Moreover, patency of ITA
gras appears to be a very stable situation. Some observational
studies have now extended out to 30years, showing that if an
ITA to the LAD gra is patent 5years aer operation it is very
unlikely to ever become occluded. In situ ITA gras to the circumex coronary artery are almost as reliable as those to the
LAD. ITA gras constructed to the RCA do not have as high a
patency rate as do those to le- sided vessels, but it is dicult
to isolate the ‘right coronary eect’ from the ‘moderate stenosis
eect’. An ITA gra, or any arterial gra, constructed to a vessel
with a non- signicant stenosis is less likely to function well than
an arterial gra to a severely stenotic vessel, probably because
of competitive ow through the native coronary. is competitive ow appears to lead to the creation of the ‘string sign’, a diminished gra diameter and possible eventual occlusion of the
arterial gra. However, graing a marginally stenotic coronary
artery with an ITA gra does not appear to make the clinical
situation worse as recent data indicate that patient survival is
not compromised. e disadvantage of graing a mildly or
moderately stenotic vessel is that it risks wasting the ITA as an
eective gra. ‘Free’ gras, those with a proximal anastomosis
constructed to the aorta, or another ITA gras appear to have a
slightly diminished patency rate, but that decrement appears to
be based on technical issues rather than an intrinsic predisposition to occlusion of free gras.
e prediction of long- term patency for all types of bypass
gras has been complicated by changes that have taken place
over the last 20years that make some of the conclusions from
older studies less reliable. First, vein gra atherosclerosis is
not as dramatic as it used to be. is probably results from effective perioperative and postoperative pharmacological therapies that include aspirin and statins. Second, techniques for
harvesting the saphenous vein have changed in the direction of
endoscopic approaches that clearly have decreased the likelihood of wound complications, but may increase the incidence
of submaximal damage to the vein. Some smaller studies have
shown favourable vein gra patency rates when preparation
techniques considered less traumatic have been employed.
ese considerations along with the fewer postoperative
studies done today make it dicult to know what the relative
long- term patency rates of vein and ITA gras may be in the
modern era. However, the vast bulk of data indicate that ITA
gra patency is better than that for SVGs and that advantage
widens with time, except for gras to the RCA or to moderately
stenotic vessels.
e situation is even more complicated when non- LAD ITA
gras are compared with RA gras. e RA gra has several
advantages compared to a BITA strategy. e RA can be prepared concurrently with the LITA, saving operative time, and
usually is larger, thicker, and easier to work with than the RITA.
It also does not increase the risk of sternal complications. When
sequential arterial gras are contemplated, the RA is particularly more forgiving than an ITA gra. e excellent and relatively recent patency studies comparing SVG and RA gras
seem to show to my eye that at 5years the eective patency
rate of RA gras is better than that for SVG gras, but only
slightly. Additionally, there are observational studies that appear to show equivalent late patient survival with the BITA and
LITA– RA approaches, both being superior to the LITA– SVG
strategy. At this point, those studies are dicult to interpret
(as the follow- up intervals are shorter than comparable BITA
follow- up intervals), but certainly the RA gra may provide an
advantage to many patients. My concern about the strategy of
substituting the RA for the RITA for most patients is the occasional unexpected occlusion of an RA gra in a situation where
gra failure would seem unlikely. At this point, it is my opinion
that in a perfect situation (tightly stenotic le- sided vessel, patient that is not obese) the RITA gra produces the most reliable
long- term outcomes despite the increased operative challenge
it represents. Time will tell whether the RA and RITA patency
and survival curves will separate. We do use both the RITA and
a RA gra for many patients.
6. Once an ITA gra passes the 5- year follow- up mark and it is pa-
tent, it is likely to stay patent indenitely. Late ITA compromise
by atherosclerosis, the long- term nemesis of SVG gras, is exceedingly rare, although progressive subclavian occlusive disease
may compromise gra ow.
Preoperativeevaluation
Part of a preoperative coronary angiogram should be a study of at
least the LITA and preferably both ITAs. Intrinsic ITA or subclavian
disease is uncommon but may occur. In re- operative situations, an
angiogram is essential as the ITA may have been damaged during
the previous procedure. It is also helpful to know what other conduits may or may not be available, information that may be obtained
with non- invasive studies.
Conduitpreparation
Most BITA operations are performed through a median sternotomy
and from the very start this incision must be made with the assumption that sternal ischaemia will be present when the operation is
completed. Use of electrocautery must be minimized and attention
paid to maintaining collateral ow through the inferior epigastric
system. e sternum should be divided with the sternal saw and
electrocautery used only on specic periosteal bleeding points. We
have routinely opened both pleurae to allow the ITA gras to take
the most direct route to the point of graing and to prevent tension
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on the ITA gras from the expanding lungs. e endothoracic fascia
overlying the ITA is incised with scissors, exposing the ventral surface of the ITA, and a skeletonized dissection is carried out. When
possible, the ITA branches are divided with scissors between two
small haemoclips. is dissection is a meticulous process and may be
time- consuming. Proximally, the ITA is taken to the rst intercostal,
which must be clipped and is usually divided. On occasion it will be
dicult to expose well and clipping alone must suce. Distally the
LITA should be dissected as far distally as long as is needed to reach
the LAD at the point where it is to be graed. at point is usually
not distal to the major bifurcation of the ITA, and ‘extra’ LITA length
should be taken only if a Y- gra to a diagonal is contemplated.
Preparation of both ITAs should be undertaken with the plan for
graing in mind so it will be possible to dissect only those lengths
that will actually be needed. Sternal ischaemia usually is most clinically important in the inferior sternum and maintaining the inferior
epigastric collateral supply to extend as far superiorly as possible is
important. For example, if a LITA– RITA Y- gra is contemplated and
a gra to a RCA branch is not planned, it is not necessary to prepare
the RITA all the way to its bifurcation. Conversely, if the operative
plan is to use the distal LITA as a Y- gra to a diagonal branch, then
the LITA must be prepared quite far distally. Making these decisions accurately will help to minimize sternal devascularization and
should be made with an understanding of the coronary angiogram,
ITA size and length, and, sometimes, opening the pericardium to inspect the targets. Once the ITA gras are prepared they are wrapped
in papaverine- soaked sponges, le in place, heparin is given, and
cannulation is undertaken if on- pump surgery is contemplated.
is treatise does not hope to resolve the on- vs o- pump debate,
but in our own practice we usually use cardiopulmonary bypass and
cardiac arrest with cardioplegia for performing all anastomoses as
BITA procedures are oen technically complex operations where a
substantial price can be paid for technical error, particularly if sequential ITA gras are contemplated. at being said, BITA graing
can be very appropriate in conjunction with o- pump surgery as all
aortic manipulation can be avoided with this approach, and ‘simple’
BITA graing such as LITA to LAD with a Y- gra RITA to circumex is little more dicult than using vein gras.
Graft configuration andanastomoses
Our usual BITA conguration is to place the LITA to the LAD and
to use a RITA Y- gra from the LITA to gra the coronary vessels
of the lateral wall of the heart. At this point in the operation, the
Y- gra is constructed. e LITA is rotated to allow access to the anterior aspect, then xed to the chest wall with 6- 0 silk adventitial
sutures. is makes the LITA an immobile xed target. An incision is then made longitudinally in the LITA about twice the length
of the diameter of the proximal RITA and an 8- 0 Prolene® suture
is used to construct a continuous 90° anastomosis starting in the
proximal aspect of the LITA incision. e proximal aspect of the
RITA has been spatulated and is larger in area than the LITA incision
(Fig. 33.1). is right- angled anastomosis allows the greatest exibility in gra positioning, and prior to cardiopulmonary bypass the
Y- gra is placed on the anterior aspect of the heart and the intended
route of the gra visualized. If the anastomosis does not turn out to
be exactly at 90° that is not a disadvantage.
Fig.33.1 The graft- to- graft anastomoses of the RITA to the LITA is a critical part of the ‘Y’ arterial graft procedure and is carried out with the vessels
fixed to the chest wall to eliminate instability and motion.
LITA-RITA
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anastomosis
LCX
LITA to LAD
OM1
OM2
OM3
LVA
Fig.33.2 Sequential ITA grafts are constructed with the graft and native
vessel parallel. The end anastomoses may be constructed in a rightangle fashion. LCX, left circumflex; LVA, left vertebral artery; OM, obtuse
marginal.
33 Early development of internal thoracic artery grafting 265
interrupted strategy is that it avoids tension on the wall of the gra as
most of the sutures can be placed before they are tied, avoiding tension on those sutures that have already been placed in the gra. e
disadvantage is that there is a premium on rapid tying without tension. e ITA gra is much more fragile than the SVG and damage
to the gra is a much greater danger than when an SVG is employed.
Once the anastomosis is completed the gra is open to ow, allowing
it to be examined and the length to the next anastomosis to be measured. Once the initial anastomosis is carried out, the gra is curved
to allow it to approach the next vessel with the ITA and the native
coronary artery being parallel. e nal end- to- end anastomosis of
a sequential gra may be carried out as a right angle, rather than a
parallel anastomosis as the end of the ITA is usually large enough
to match the coronary arteriotomy. With a serpentine gra it is not
always the case that the RITA will reach comfortably to the posterior
descending branch, and if that is an important and severely stenotic vessel it may be best to forgo the intervening circumex anastomoses in order for the length to be adequate to reach the posterior
descending artery. e circumex is then graed with a RA or SVG.
When the lateral and posterior wall anastomoses are completed,
and all the proximal anastomoses (if RA or SVG gras are used) have
been accomplished, the LITA to LAD anastomosis is completed. We
rarely employ a sequential ITA to the diagonal– LAD system and do
so only if it is not necessary to curve the ITA to accomplish the task
(which creates the risk of kinking and decreasing ow). If we cannot
gra a diagonal with the RITA gra we may use a separate short segment Y- gra to the diagonal, and despite an extra anastomosis we
consider this to be a safer approach (Fig. 33.3).
Once all anastomoses are completed, the cross- clamp is removed from the aorta and the heart is allowed to recover. At this
point, the lungs are inated and the lie of the gras is examined.
We then initiate cardiopulmonary bypass, use aortic crossclamping and antegrade and retrograde cardioplegia for myocardial
protection, and construct all anastomoses during a single period of
aortic cross- clamping. When saphenous vein or RA gras are intended, they are constructed rst.
Usually the RITA portion of the Y- gra is used to revascularize
lateral le ventricular vessels, proximal diagonal and circumex
branches. e order of graing coronary vessels is proximal to distal,
so diagonals are approached rst followed by circumex vessels.
is allows the surgeon to open the gra aer each anastomosis to
check for leaks and to measure the correct length between vessels.
e increase in length when an ITA gra is lled with blood is variable. Also, all anastomoses of sequential ITA gras are constructed
with the gra parallel to the native coronary artery, meaning that
the RITA gra progresses from proximal to distal in a serpentine
fashion, and making the measurement of length important (Fig.
33.2). Commonly, a large proximal diagonal will be the rst vessel
graed and the direction of the parallel anastomosis will be retrograde. e coronary arteriotomy will be about twice the diameter of
the coronary vessel and the arteriotomy in the ITA should be slightly
longer. e ITA should not be stretched to accommodate the native arteriotomy. Saphenous vein can be slightly stretched, the ITA
cannot. Ipersonally use an interrupted anastomosis with 7- 0 silk for
all distal ITA anastomoses, but most surgeons employ a continuous
technique utilizing 7- 0 or 8- 0 polypropylene. e advantage of an
Fig.33.3 A‘Y’ graft from the LAD to a proximal diagonal is less likely
to kink at the anastomoses than is a sequential graft, as shown in this
postoperative angiogram showing complete left coronary artery ITA
revascularization.
SECTION 6 Conduits forcoronary artery bypass graft surgery266
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We usually open the pericardium on the le side posteriorly towards the phrenic nerve to allow the LITA a direct route to the LAD
area. Cardiopulmonary bypass is then discontinued. With the heart
full, the lie of the gras is then re- examined and if needed they are
tacked to the epicardium with 6- 0 silk sutures through the adventitia. Protamine is given, and haemostasis is obtained. Athoracic
tube is placed in each hemithoracic cavity and a single one is placed
in the mediastinum through the midline abdominal fascia. We make
a point of avoiding damage to either of the inferior epigastric arteries
by either chest tube or pacing wire placement.
Sternalclosure
We assume that a relative degree of sternal ischaemia is present
during the closure, and place 12 individual wires to the sternum.
Others have used more complex sternal closures including doubled
wires and various closure devices which may be reasonable although
more expensive. It is important to obtain a tight sternal closure and
surgical procedure that accounts for much of the surgical programme
at many centres. Whereas few cardiac surgeons believe they are equally
capable at pulmonary valve autotransplantation, neonatal switches,
thoracoabdominal aneurysm resections, and cardiac transplantation,
it is believed that most surgeons should do coronary bypass surgery,
leading to acceptance of simpler procedures in the coronary arena.
is trend has been enhanced by the attitude of the professional societies concerning this issue, which has been to encourage BITA use, but
not to demand it. at posture has probably been wise considering
the likelihood that if BITA use was mandated, it might engender an
increase in short- term complications for heterogeneous patients and
heterogeneous surgeons. However, there are some aspects of coronary
surgery that are not generic, BITA graing being one, and the patient
who is a good candidate with severe multivessel disease, tight lesions,
and a long life expectancy should undergo surgery in a situation where
they are likely to receive BITA graing. At this point, it is the best op-
eration that we can do for such a patient.
perfect opposition of the sternal edges. e muscle and fascial layers
over the sternum are closed with interrupted absorbable sutures and
the skin with a subcuticular closure.
e best way to avoid the potential complications of a median
sternotomy would be to use an alternative access, and some small
numbers of operations have been done using the BITA strategy with
small thoracotomy access, oen with the assistance of robotics technology. ITA preparation is very straightforward with this approach,
and with time, enough surgeons may become facile enough with this
approach for it to impact surgery signicantly. At present, these are
experimental procedures and should only be done in institutions
and by surgeons with a substantial commitment to these investigations including careful follow- up.
Role ofBITA grafting incoronary
revascularizationtoday
Despite volumes of data that support the use of the BITA strategy
and the superiority of the long- term outcomes that it produces, it
has not become a standard revascularization principle. ere are
some reasons for this that are understandable, and some less so.
BITA graing does increase the risk of sternal wound complications.
In the modern era that risk has lessened, but still exists, particularly
for diabetic and obese patients. e ‘payo’ of the BITA operation is
only clearest aer the 10- year mark whereas surgeons and hospitals
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