Coronary surgery without cardiopulmonary bypass.
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ABSTRACT: Objective: To analyze the difference in coronary artery bypass grafting (CABG) performed with normothermic cardiopulmonary bypass (CPB) and CABG supported with the intracardiac microaxial pump (ICP, Impella, Aachen, Germany). Methods: A prospective randomized study was conducted in seven centers. The study population consists of 199 patients undergoing isolated primary CABG (CPB group 94 patients, ICP group 105 patients). Both groups are equal in demographic variables, number of bypasses performed, and Euroscore predicted mortality. We analyzed clinical outcome, myocardial enzymes and blood parameters of hemolysis, organ function and inflammatory response. Results: Seventeen patients (16%), randomized in the ICP group, were switched to the CPB group. This was due to the inability to position the right side catheter adequately ðn ¼ 8Þ, to a pump failure ðn ¼ 1Þ or to the perioperative decision that beating heart surgery is technically not possible ðn ¼ 8Þ. There was no significant difference between the two study arms regarding the pump assistance time (CPB 67.1 ^ 22.9 min; ICP 67.7 ^ 30.3 min; P ¼ 0:88861), the number of grafts (CPB 2.4 ^ 0.7; ICP 2.3 ^ 0.8) and the number of grafts to the back wall (CFX; both groups n ¼ 37). There is no significant difference in clinical outcome, evolution of myocardial enzymes, indices of organ function and hemolysis. There is a reduced inflammatory response in the ICP group as indicated in the postoperative release of granulocyte elastase (CPB 259 ^ 195; ICP 150 ^ 126 mg/l; P , 0:00001) and complement C3 (CPB 0.73 ^ 0.2; ICP 0.65 ^ 0.2 g/l; P ¼ 0:008). Conclusion: The intracardiac pump for the right heart is difficult to introduce. As a consequence the right side pump underwent design modifications. There were no differences in clinical outcome between both groups. The inflammatory response is significantly reduced in the ICP group. q 2002 Elsevier Science B.V. All rights reserved.
Br HeartJ 1995;73:203-205
Coronary surgery without cardiopulmonary bypass
The drive towards cost containment is changing clinical
practice, and the emphasis is now on less invasive proce-
dures and simplicity.' The economic arguments for coro-
nary angioplasty (PTCA) are currently limited by high
restenosis rates and the need for further intervention
within the first three months (> 30%).2-4 Though from a
surgical perspective the results of coronary artery bypass
grafting (CABG) are clearly superior, excessive surgical
waiting times and the lesser immediate expense are used
to justify diversification of PTCA to patients with multi-
vessel disease.5 These arguments are reinforced by adding
to the equation the damaging effects of cardiopulmonary
Interaction between blood and foreign surfaces acti-
vates complement and neutrophils to produce a whole
body inflammatory response.6 Intrapulmonary sequestra-
tion of white cells, with generation of free radicals and
protease enzymes, causes the interstitial oedema gener-
ally implicated in the need for postoperative ventilation.7
These mechanisms, together with systemic microem-
bolism also have effects on the brain and kidney.89 The
bypass, which are well documented and perhaps over-
patient.'1-12 They argue in favour of an expeditious sur-
geon and short bypass times (< 60 minutes), or indeed
against cardiopulmonary bypass. Clearly, there are short-
term clinical reasons to avoid cardiopulmonary bypass
and to these can be added the cost of equipment (about
£500 in disposables), intensive care, and extended hospi-
tal stay. Many aspects of cardiac surgery have been taken
for granted since development of the specialty in the late
1950s. At the Oxford Heart Centre efforts to simplify
cardiac surgery have recently extended to performing
CABG without cardiopulmonary bypass
patients. Coronary surgery is undertaken without open-
ing a cardiac chamber and consequently it is not neces-
divert blood from within the
continued ventilation of the lungs and unimpaired pul-
monary blood flow there is no need for an oxygenator.
The only technical requirement for CABG is a bloodless
anastomotic field. This can be achieved by temporary
coronary occlusion while the heart continues to support
the circulation through uninterrupted cardiac action.
Besides the historical documentation of this approach we
have become increasingly aware from PTCA experience
that coronary occlusion and myocardial ischaemia are
surprisingly well tolerated for up to 15-20 minutes."'>6
This is longer than the time needed to isolate a coronary
artery in the beating heart, open the vessel, and apply
either an internal mammary or saphenous vein graft.
The PTCA principle of addressing the culprit lesion by
non-pump CABG could be applied to certain high
risk patients but the method is mostly used for those in
whom complete revascularisation can be undertaken
through the left anterior descending and right coronary
Lessons from previous experience
In the early 1950s, before cardiopulmonary bypass came
into use, coronary endarterectomy, coronary excision
with interposition vein grafts, and both saphenous vein
and internal mammary artery bypass were performed
experimentally and on patients without significant mor-
bidity or mortality. 14-16 William Longmire first performed
an anastomosis between the left internal mammary artery
and the left anterior descending coronary artery in 1958.
Longmire recalls "At the time we were doing the coro-
nary thromboendarterectomy procedure, we also I think
performed a couple of the earliest internal mammary to
coronary anastomoses. We were forced into it when the
coronary artery we were endarterectomising disintegrated
and in desperation we anastomosed the internal mam-
mary artery to the distal end of the right coronary and
later decided it was a good operation." Sabiston per-
formed a right coronary saphenous vein graft in 1962 and
DeBakey succeeded with a saphenous vein bypass of the
left coronary artery without extracorporeal circulation in
1964, though the event was published only after 7 year
follow up showed
Widespread adoption of cardiopulmonary bypass and
cold cardioplegic arrest made CABG easy and provided
the stimulus for a dramatic increase in the number of
procedures from 1968 onwards.'7 This stifled further
efforts to operate on the beating and unsupported heart
at a time when vascular surgical techniques remained
Ankeney in 1972 described 143 patients in whom car-
diopulmonary bypass was not used.18 Buffolo
reported coronary bypass by simple interruption of coro-
nary flow in 1985 and the same year Frederico Benetti
and his group described their initial experience from
Buenos Aires.'9 20 Benetti's experience of more than 2000
cases was stimulated by limited resources. Non-pump
CABG allowed a substantially greater throughput of
patients than would otherwise have been possible.20
Postoperative angiography has shown no significant dif-
ference in graft patency between bypass and non-bypass
patients when the saphenous vein or the intemal mam-
mary artery was used.20
Others have followed Benetti's lead for elective, emer-
gency, and re-operative coronary bypass. Pfister et al
of the Washington Hospital Centre, reported 220 opera-
off bypass, comparing the outcome with 220
conventional operations matched for number of grafts,
left ventricular function, and date of operation.2' They
that the graft was
concluded that selected patients with disease of left ante-
rior descending and right coronary arteries can safely
undergo CABG without cardiopulmonary bypass and
that left ventricular function was better preserved than
after cold cardioplegic arrest.
The superior preservation of left ventricular function
despite periods of "unprotected" regional ischaemia fol-
lowed by reperfusion was described by Akins et al in a
comparative study ofCABG performed with and without
extracorporeal circulation.22 They found that postopera-
tive septal wall motion was abnormal in patients operated
on with cardiopulmonary bypass, aortic cross clamping,
and myocardial preservation techniques, whereas those
operated without had either no change or an improve-
ment in septal motion after revascularisation. Benetti et al
explored this aspect by performing intraoperative left
ventricular biopsies and showed superior preservation of
the mitochondria in the non-bypass patients.2' Clearly
myocardial stunning does not become important in non-
pump patients despite occlusion times of 10-15 min-
utes.2425 Myocardial reperfusion injury has a central role
in the pathophysiology of myocardial stunning after peri-
ods of coronary occlusion, but the effects of obstructing a
previously normal vessel are not the same as for an
obstructed or severely narrowed diseased vessel. A clue
to the absence in stunning after non-pump reperfusion,
compared with reperfusion after global ischaemia during
cardiopulmonary bypass, is that the interaction between
blood and foreign surfaces activates leucocytes which are
implicated in the mechanism ofreperfusion injury.26
Collectively, the data from these groups suggest that
non-pump CABG procedures are safe, cost effective, and
advantageous-notably, for those with impaired ventri-
cles, for hypertensive patients, certain reoperations, and
for those with carotid and renal disease.27 Those who
refuse blood transfusion benefit through preserved coag-
ulation and minimal blood loss. The method is best
applied for those in whom revascularisation is complete
with one to three grafts in the accessible territories.28 29
For those at high risk of morbidity from cardiopulmonary
bypass-for example, those with a calcified (eggshell)
aorta or carotid occlusion-grafting of a culprit lesion in
an accessible territory with one or both internal mam-
mary arteries is preferable to the near certainty of cere-
Technical aspects ofnon-pump coronary surgery
The Oxford experience is limited but we have used both
vein grafts and the left internal mammary artery and have
achieved extensive right coronary endarterectomy on the
beating heart. With appropriate planning the operation is
safe and causes surprisingly little haemodynamic insta-
bility. Anaesthetic methods are modified to allow extu-
in the immediate postoperative
operating conditions are clearly not as good as for cardio-
plegic arrest but are not dissimilar to those of intermit-
tent aortic cross clamping with a fibrillating heart. The
occlusive, stay sutures provide access and stability to the
coronary artery and, with practice, hand/eye coordination
adapts to the rhythmic movement. A certain degree of
surgical skill is needed to suture a 1P5 mm mammary
artery to a moving target of 2 mm diameter. It will be dif-
ficult to match Benetti's results, but experience and
familiarity with the approach leads to greater ease, accu-
racy, and confidence. Benetti grafts the circumflex coro-
nary from the front and Faro has used left thoracotomy
for reoperative circumflex grafts, without bypass." We
reserve non-pump CABG for tightly occluded or highly
stenotic well collateralised and easily accessible lesions of
the left anterior descending or right coronary arteries.
The issue of complete revascularisation in non-pump
operations is of concern. Interventional cardiology has
usurped many of the straightforward one and two graft
cases, but with informed consent based on the ran-
domised trials of CABG versus PTCA for multivessel
disease, more patients with the combination of left ante-
rior descending right coronary artery disease are likely to
opt for surgery.2-5 The fact that PTCA of the culprit
lesion(often with sacrifice of diagonal or marginal
branches) gained acceptance in the medical community
is an argument in support of non-bypass procedures,
given that PTCA offers less protection to the patient than
non-pump CABG. However, a note of caution is needed.
In the discussion of Pfister's paper, Gundry of Loma
Linda, described a similarly encouraging in hospital
experience with 128 patients but an inordinate number
of graft anastomotic stenoses and narrowings occurred at
the site of the loops placed around the diseased vessel.
This, together with several unexpected
caused the Loma Linda
Further investigations are appropriate in certain cate-
gories of patient because non-bypass CABG can be per-
formed without added risk and at a cost similar or less
than multivessel PTCA. What then is the future for
CABG? Cardiopulmonary bypass is still necessary to per-
form multiple grafts, including those in the circumflex
territory, and when there are combinations of lesions
which carry exorbitant risk. Myocardial protection with
cardioplegia provides a motionless and bloodless field
that expedites surgery. Coronary surgery without car-
diopulmonary bypass is already applicable in the circum-
stances described but its use may expand with the use of
axial flow pumps, which provide circulatory support
without the need for extracorporeal circulation. With
continued innovation it is likely that CABG (a closed car-
diac operation) will soon be performed routinely without
the heart/lung machine.
In conclusion, coronary surgery without cardiopul-
monary bypass is safe, eliminates both the need for blood
transfusion and the damaging effects of cardiopulmonary
bypass, and allows extubation on the operating table.
Patients can be discharged from hospital on the fourth or
fifth postoperative day. The disadvantages of the method
are the limitation to two vessel disease, a technically
more challenging anastomosis, and a question mark over
graft patency if snares are used. However, with costs
equivalent to angioplasty and a longer lasting result use
ofthis method must increase.
Oxford Heart Centre, John Radcliffe Hospital,
Headington, Oxford OX3 9DU
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