1. Anaesthesia for off pump
coronary artery bypass grafting
- the current concepts
Presented- DR. SACHIN BANSAL
Moderator- DR. ANJUM

2. DEFINITION
 Off-pump coronary artery bypass or "beating heart"
surgery is a form of coronary artery bypass
graft (CABG)surgery performed without cardiopulmonary
bypass (heart-lung machine) as a treatment for coronary
heart disease During most bypass surgeries, the heart is
stopped and a heart-lung machine takes over the work of
the heart and lungs.
 When a cardiac surgeon chooses to perform the CABG
procedure off-pump, also known as OPCAB (Off-pump
Coronary Artery Bypass), the heart is still beating while the
graft attachments are made to bypass a blockage.

3. Historical aspects
 the first open heart surgery was performed by John
Gibbon in 1952 using cardiopulmonary bypass
 First successful OPCAB was performed in 1961 and
Kolesov in 1964 performed the first successful
anastomosis of left internal mammary artery to left
anterior descending artery
 In 1967 Favalaro and Effler performed reversed
saphenous vein grafting.
 In 1968 Green performed anastomosis of the internal
mammary artery to the coronary artery.

4. Off pump coronary artery bypass grafting vs. on
pump coronary artery bypass grafting
 Systemic inflammatory response syndrome
(SIRS) -A combination of non pulsatile flow, myocardial
ischaemia, hypothermia and contact of the patient blood
with the artificial surface of the extra corporeal circuit is
responsible for the inflammatory process.
 Coagulopathy-disruption of the coagulation system
and haemodilution after cardiopulmonary bypass is
avoided in OPCAB.

5. Off pump coronary artery bypass grafting vs. on pump
coronary artery bypass grafting
 Neurologic dysfunction-four major causes-
embolization, inflammation, hypoperfusion and
hyperthermia.
Two type-1. death either due to stroke or hypoxic
encephalopathy,stuper n coma. Risk factors
are diabetes mellitus, atherosclerosis in the proximal
aorta and preexisting impairment of cerebral blood
flow.
Type-2- intellectual dysfunction, memory deficits,
confusion or agitation are due to small micro emboli
and inadequate perfusion

6. The incidence of stroke after OPCAB is about 1% when compared
to 9% after CABG
•Myocardial injury:-
myocardial injury as assessed by biochemical markers is much
less after OPCAB when compared to CABG.
•Pulmonary dysfunction:
CABG pulmonary dysfunction may be caused by alveolar
atelectasis, inflammation, increased shunting, and volume
infusion.
. The rate of renal failure is lower in patients undergoing
OPCAB.

7. The goals of anaesthetic
management
Provision of safe anaesthesia using a technique that
offers maximum cardiac protection and stability
 Maintaining haemodynamics in the intraoperative
period by physical and pharmacological methods
 Allowing early emergence, ambulation
 Providing adequate pain relief in the postoperative
period.

8. Preoperative anaesthetic
assessment
 Preoperative optimization of diabetes, hypertension and
reactive airway is essential.
 Preoperative assessment of the carotid arteries is routinely
carried out.
 Preoperative transthoracic echocardiography, chest X ray,
and ECG serve as baseline investigations.

9. Preoperative anaesthetic
assessment
 Beta blockers should continue to receive it in the same
dose
 Anti platelet medications should be stopped atleast 1 week
prior to surgery
 ACE inhibitors should be stopped 24 to 36 hours prior to
surgery.
 The last dose of low molecular weight heparin should be 12
hours prior to surgery & unfractionated heparin 6 hours
prior to surgery.
 review the coronary angiogram for a patient with poor left
ventricular function coupled with small caliber coronary
arteries.

10. Premedication
 Benzodiazepines, opioids and anticholinergic
medications.
 0.05mg.kg -1 of midazolam and 1µg.kg -1 of
fentanyl are administered intramuscularly
thirty minutes prior to surgery.
 provide supplemental oxygen.
Before insertion of intravenous and arterial
cannulae administer additional midazolam
and fentanyl.

11. Monitoring
Electrocardiogram (ECG)-well visualized 'P' wave and
QRS complex prior to commencing the surgery.
Non invasive monitors- include pulse oximetry and
capnography.
Invasive blood pressure monitoring-By radial or
femoral artery.
 The cannulation of the femoral artery not only permits
access to the central arterial tree but provides access to
quick insertion of an intra aortic balloon pump.
 If radial artery cannulation is planned the Allen's test must
be performed prior to performing cannulation.

12. Pulmonary artery catheter (PAC)-
PAC is usually via the right internal jugular vein.
Indication-
 Ejection fraction less than 0.4.
Significant abnormality of the left ventricular wall
motion.
LVEDP greater than 18 mm Hg at rest.
Recent MI and unstable angina.

13. pulmonary artery catheter
(PAC)-
Post MI complications
 VSD
 LV aneurysm
 Mitral regurgitation
 Congestive cardiac failure
Emergency surgery
Combined procedures
Reoperations

14. Transesophageal echocardiography
(TEE)
Advantages-
 Identify myocardial ischaemia early by detecting regional wall motion
abnormalities.
 assess left ventricular dysfunction intra operatively.
 assessing the improvement in myocardial function after the
completion of revascularization.
Dissadvantage- Inability to image the required part of the heart
during grafting .
Monitoring of urine output, oropharyngeal and rectal
temperature is essential.

15. INDUCTION
 induction should be slow.
 induce general anaesthesia by inhalational
technique by either sevoflurane or isoflurane
in 1-2 minimal alveolar concentration.
 Neuromuscular blockade is achieved by
injecting 0.7 mg.kg -1 of rocuronium intra-
venously prior to intubation.
 Maintenance of is achieved with an infusion
of fentanyl, atracurium and isoflurane.

16. Intraoperative management
 Hypotension-
 treated with volume loading.
 adequate heart rate in sinus rhythm.
 increasing afterload to maintain systemic perfusion
pressures.
 Inotrope therapy should ,like dopamine, epinephrin &
dobutamine by infusion.
 informing to surgeon for cotton packs under heart and
the epicardial stabilizers should be repositioned.
 resting the heart in the pericardial cavity.
 If there is no improvement, an intra aortic balloon pump
support can be instituted.

17. Intraoperative management
Arrhythmia-
 Use lidocaine (without preservative) infusion if
patient has arrhythmia caused by myocardial
ischaemia.
 If arrhythmias caused by electrolyte imbalance
then start an infusion of potassium chloride and
magnesium chloride.

18. Intraoperative management
Intraoperative heparinisation and
neutralization-
 The dose of heparin is 2mg.kg -1 (200 units.kg -1 )
intravenously.
Activated clotting time( ACT) should be per-
formed 3 minutes after administration.
 The goal is to keep the ACT between 250 - 300
seconds.

19. Intraoperative management
ACT should be repeated hourly and repeat
bolus of 5000 units intravenously is essential
if the ACT value is less than 250 seconds.
Heparin is reversed with protamine sulfate
with dose 1 mg/1mg of heparin.
 Acceptable ACT is in the range of 130 to 140
seconds after protamine administration.
A high ACT will require additional protamine
in a dose of 25 to 50 mg.

20. Prevention of hypothermia
Warm blanket covers in the pre operative
Period.
Keep the operating theatre warm till
induction and there after the temperature can
be decreased gradually.
The time taken for sterile preparation by
painting and draping by sterile sheets should
be kept to the minimum.

21. Prevention of hypothermia
 Spillage of cold fluids on the patient is
avoided by draping the patient with
waterproof sheets.
 intravenous fluids intended for use are
warmed by fluid warmers.
Low fresh gas flows with carbon di oxide
reabsorption circuits.

22. Prevention of Myocardial
ischaemia
Maintaining systemic blood pressure by keeeping
mean arterial pressure of at least 70 mm Hg all
times by administration of boluses intravenous
fluid and Trendelenburg position.
Reduction in myocardial oxygen consumption by
avoiding tachycardia , using intraoperative beta-
blockers or calcium channel blockers.
 Ischaemia during distal anastomosis can be
prevented by using intraluminal coronary
shunts .

23. Intracoronary
shunts
These are double
limb shunts that fit
into the proximal
and distal ends of
the open coronary
artery

24. Intracoronary shunts
Benefits:-
Native coronary arterial blood flow is
maintained preventing intraoperative
ischaemia.
Blood loss during coronary anastomosis is
avoided or decreased.
The coronary stent prevents embolization of
carbon dioxide into the coronary arteries.

25. Intracoronary shunts
 shunt prevents the surgeon from taking a
suture on the posterior wall of the coronary
artery.
Presence of the shunt assures a proper coro-
nary anastomosis.
 insertion of intraluminal coronary shunts will
reverse the changes caused by ischaemia like
myocardial oedema, endothelial and
contractile dysfunction.

26. Haemodynamic changes related to
heart position
Lifting and rotating the heart during
OPCAB can alter the haemodynamics such
as cardiac output, stroke work, left
ventricular end diastolic pressure and right
atrial pressure.
 During grafting of right coronary artery
bradycardia can occure due to reduction in
blood supply to the sinus and AV nodes, so
if required use atropine and atrial pacing .

27. Haemodynamic changes related to
heart position
During grafting of the right coronary artery and
obtuse marginal branches "verticalization" of the
heart is required, so posterior pericardial stitches
and a gentle retracting socket will greatly
facilitate haemodynamic .
 Reduction in the dose of intravenous
vasodilators can increase the haemodynamic
changes. During such times it may be essential to
reduce the dose of the vasodilator and add a
vasoconstrictor.

28. Post operative management
 Get a 12 lead electrocardiogram for any fresh changes like
ischaemia or myocardial infarction & treated with low molecular
weight heparin, anti platelet medications, insertion of an intra
aortic balloon pump or revision of grafting.
 During transfer of the patient continuous monitoring of ECG ,
pulse oximetery and invasive blood pressure is essential.
 Always carry prefilled syringes of diluted 1:200,000 adrenaline,
1.2mg of atropine and 100mg of lidocaine (preservative free) to
treat a crisis during the transfer phase.
 cardiac index and partial pressure of oxygen is decreased and
took almost 15 to 20 minutes to return to baseline.

29. I.C.U. management
Patients are connected to the ventilator:-
parameters are as follows:-
 FiO2 of 0.8
 tidal volume- 7-10 ml.kg -1
 frequency -12- 15/min
 I:E ratio of 1:2, and controlled mode of
ventilation.
Arterial blood gas analysis is performed after
thirty minutes. FiO2 is reduced to 0.4 if
oxygenation, carbon dioxide elimination and
tissue perfusion.

30. I.C.U. management
Thirty minutes later a reassessment of-
 blood loss (not more than 10% of blood volume)
 fluid balance (not more than 10-15 ml.kg- 1 body
weight)
 core temperature ( not less than 35 deg Celsius ),
 arrhythmias
 urine output (at least 1-2 ml.kg -1 .hr-1 ) are done.
If the residual neuromuscular blockade is present
then reversed by injecting a combination of
neostigmine and glycopyrrolate.

31. I.C.U. management
After confirming adequacy of reversal
ventilatory mode is switched to the
spontaneous modes of ventilation, such as
pressure support, or continuous positive
airway pressure.
Thirty minutes after supported ventilation
arterial blood gas analysis is repeated and If
the analysis shows satisfactory values of
oxygenation, carbon dioxide elimination and
metabolism, the patients are extubated.

32. Fast track anesthesia
 Defined:- as tracheal extubation within 8
hours after cardiac surgery, early mobilization
of patient and early discharge from the
hospital.
 availability of short acting opioid
medications have made it possible to subject
the patients after cardiac surgery to fast track
anaesthesia.
.

33. Fast track anesthesia
 Early extubation resulted in regaining the
cough reflex and thus a lower incidence of
atelectasis and pneumonia.
 All patients may not be suitable for fast
tracking; presence of bleeding, dysrryhtmias
and haemodynamic instability warrant
ventilation till stability is achieved.
 Long acting sedatives should be avoided

34. Management of postoperative
pain
 Epidural analgesia:- begin an epidural fentanyl
infusion with Fentanyl 3000 mcg (60 ml), 0.5%
bupivacaine 55ml and saline 155ml are added to make a
final total volume 265 ml & start at a rate of 2ml.hour-1
Intravenous opioids:- Fentanyl 3000mcg and
saline 215ml are added to make a final concentration 11
mcg.ml -1 of fentanyl.