Download anaesthesia for beating heart surgery

ANAESTHESIA FOR BEATING
HEART SURGERY
INTRODUCTION –
 OPCAB – performed first in
1964
 CABG with CPB
 The revival of OPCAB technique occurred in 1980
with two different approaches:
 MIDCAB- anastomozing the LIMA to LAD through
small ant left thoracotomy.
 The second approach is multivessel grafting without
CPB performed through a standard median
sternotomy, which gives access to all coronary
vessels, and allows standard techniques of
mammary artery harvesting.
 The challenge in beating heart CABG surgery is that it
can be difficult to suture or "sew" on a beating heart.
The surgeon must use a "stabilization" system to keep
the heart steady.
 The stabilization system consists of a heart
positioner/surgical maneuvers to position heart and a
tissue stabilizer. The heart positioner guides and
holds the heart in a position that provides the best
access to the blocked arteries. The tissue stabilizer
holds a small area of the heart ,its placed on
epicardium over the arteriotomy site to provide
regional immobilisation, while rest of the heart is
beating normally.
 The Octopus® Tissue Stabilizer. Hs 2 flanged suction
devices with cups under the flanges which lift &
stabilize the myocardium. Its attached to vacuum of
400-600 mm hg..adv- it lifts than to compress heart.
SURGICAL ASPECT: midline sternotomy…. the left internal mammary
artery is harvested. At the time of harvesting, few
surgeons wish to administer half dose of heparin
(1mg.kg-1) to the patient. Prior to commencement of
grafting i.e. before the placement of ts stabilizers,
‘full heparinization’ is achieved by administering 23mg.kg-1 of heparin intravenously.
 ACT >240 secs is considered adequate. Repeat evry
30 min n repeat dose of heparin if required.
 The ascending aorta is exposed. A partial cross clamp
is applied onto the aorta and a hole measuring 4 mm
is punched in the ascending aorta; the ‘proximal end’
of the proposed conduit is anastomosed to aorta on
this punched hole. Followed by distal anastomosis to
coronary artery distal to blockade.
 Heart is‘positioned’ by placing a few ‘mops’
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underneath it. Then,target artery is ‘stabilized’ by
placing the epicardial stabilization devices Commonly
used are Octopus & starfish.
Stabilizing the heart to expose LAD artery and other
anterior coronary arteries does not cause serious
haemodynamic problems; however, positioning for
viewing the lateral vessels (obtuse marginals) may
cause haemodynamic changes.
After completion of grafting, residual heparinization
is reversed using protamine sulfate (1 mg for every mg
of heparin).
Pericardium & sternum closed closure.
Keep the perfusionist and CPB machine ready before.
ADVANTAGES OF OPCAB OVER
CONVENTIONAL CABG: Decreased ventilatory support & ICU stay, so
economically better.
 Decrsd mortality from 2.9% to 2.3% in OPCAB
 Decrsd complication rate from 12% to 8%
 Decreased rate of blood transfusion
 Decreased coagulopathy & renal dysfxn
 decreased neurological complications
 Its of more benefit in high risk patients.
C/I in presence of –intracavitary thrombi
-malignant vent arrythmias
-deep intramyocardial vessels
- procedure combined with valve
replacement / ventricular aneurysmectomy
PROCEDURES PERFORMED
ON BEATING HEART: Coronary artery bypass graft
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surgery (including ThoraCAB, a minimally
invasive option performed without cutting the
breastbone, as well as open-chest, beating-heart
bypass)
Surgery for atrial fibrillation
Treatment of some congenital heart defects,
such as closure of atrial septal defect
Valve repair (mitral, pulmonary, or tricuspid)
Valve replacement (mitral or tricuspid)
Ventricular reconstruction
PROBLEMS ASSOC WITH OPCAB:
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surgeon faces two main problems:
First, to obtain an adequate exposure of anastomosis site
with restrained cardiac motion; and second, to protect the
myocardium from ischemia during coronary artery flow
interruption.
For this purpose, he must displace the heart, compress the
ventricular wall, and if possible use a technique to allow
coronary perfusion while performing the anastomosis.
the anaesthetist must be prepared to handle severe
hemodynamic alterations, transient deterioration of
cardiac pump function, and acute intra-operative
myocardial ischemia.
The team must be prepared for conversion to CPB in case
of sustained ventricular fibrillation or cardiovascular
collapse
GOALS OF ANESTHETIC
MANAGEMENT
Provision of safe anesthesia using
a technique that offers max
cardiac protection and stability.
ii. Maintaining hemodynamics
through out intra-operative
period.
iii. Allowing early extubation,
ambulation.
iv. Providing adequate pain relief.
i.
MONITORING:
 ECG: most imp monitoring. Stick ECG leads on the back
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of the pt thus decreasing the dislodgement of them in
midst of surgery, as well as disturbance during handling
of chest.
must ensure well visualized P & QRS complexes b4 start
of d surgery.
its common to notice sudden disappearence of QRS in the
midst of surgery due 2 change in cardiac axis caused by
positioning of heart.
hrt manipulations modify the positional relationship
btwn the heart and surface electrodes thus shape of it is
altered as well as amplitude is reduced.. Impiaring its
diagnostic accuracy.
On monitors …Use diagnostic mode with ST segment
trending ..filtering off done.
 Pulse oximetery & capnography : - decrease in ETCO2
during heart manpulation is early sign of decrease in CO
 Intra arterial access-rt femoral preferred-coz 1st, it
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permits access to the central tree(less suceptible to
abnrml values during alterations in
BP/hypotension)..2ndly quick access to insertion of
intra-aortic balloon pump.
Rt radial preffered over left..after allen’s test…coz
with left internal mammary artery harvesting left
radial ar pulsations affected.
After artery access- take ABG & ACT samples
Venous access & CVP- although rt atrial pressures
and PCWP may b distorted wid d verticalization of
heart.
SvO2 < 50% assoc with bowel ischaemia.
 Indications 4 PAC
insertion-LVEF <40%
-significant LV wall motion
abn
- LVEDP > 18 mmHg at
rest
-recent MI & UA
- post MI complications like
VSD, LV aneurysm,MR, CCF
- emergency surgery
-combined procedure
- reoperation
BIS for awareness
monitoring.( <60 indicates
adequate depth)
 TEE- dcrsd accuracy bt still
interpretable..causes of
difficulty are…. as AIR
around hrt, SWABS near
esophagus & displacement
of heart.
uses- early MI detection, to
assess LV dysfxn, assessing
improvement in myocardial
fxn after completion of
revascularization.
beware- Akinesia due to tissue
stabilization shud nt b
mistakn for myocardial
dysfxn.
 Temp monitoring –
rectal, nasopharyngeal
 U.O.
 Blood loss- trigger for
transfusion 8 gm%
How to Avoid hypothermia : warm blanket covers in pre-op period,
 keep OT warm,
 Put warm blankets under patient,
 The time taken for sterile preparation of the
patient by painting the patient with antiseptic
solution and draping by sterile sheets should be
kept to the minimum.
 avoid spillage of cold fluids on patient by draping
with water proof sheets,
 use warm i/v fluids,
 low FGF with CO2 re-absorption circuits.
Changes in anesthetic techniques that have
emerged in patient undergoing OPCABG: Reduction in dosage of opioids.
 Use of shorter acting opioids.
 Administration of opioids in terms of infusion.
 Maintainence with inhalational agents/propofol.
 Use of TEA / intrathecal opioids
 Intensive monitoring & maintainence of
hemodynamics.
 Early extubation.
 Intensive pain management in the post-op period.
Induction & maintenance:
 Disadv of High dose
morphine-Vasodilation 4m
histamine release
- no amnesia
- prolonged resp
depression
 Preferred opioids
fentanyl
,alfenta,sufent.
- no hemodynamic
unstability
- bradycardia desired in
CAD
- post op analgesia
Disadv- amnesia not
gauranteed , incision
can cause incrs HR &
BP
opioids should form the base for
induction & hypnotics and BZDP shud
supplement it
 Induction alone wid
HYPNOTICS like
 thiopentone & propofol
unsuitable as it results
in……….peripheral
vasodilatation & myocardial
depression.
 Alone wid BDZP ( midaz
0.2mg/kg ) not suitable
as……. doesn’t abolish
surgical or intubation
stimulation.
 Also ……..dose and speed of
induction vary wid every pt.
 Risk of hypotension whn
used along wid opioids in
induction,
 give them b4 intubation to
ensure amnesia… and 2
obtund response to
stimulation opioids r used.
 In pts wid gud LV fxn-hv
strong sympth response to
inense surgical stimuluslike
incrsd HR ,BP.
 Requiring large dose of
anesthetics,BB,vasodilators
or both.
high dose opioids( fenta 2550 mcg/ kg & sulfenta 5-10
mcg/kg bolus dose) plus
BZDP thn followd by MR
bolus.
if TACHYCARDIA wid HTN
use B-blockers ( metoprolol
1mg incremental dose )
..Small bolus of thiopentone
2control if only HTN.
After induction put invasive
lines
in pts wid Poor LV
fxn…results in hypotension
with anesthetics coz of
reducton in CO/vasodilation.
thus may require
vasopressors/ionotropes./bo
th…
 BDZP given only if after
intubation HTN response
seen.
 Reduce doses of induction
agent & give incremental
doses to obtund
hyperdynamic response in
stressful stimulations.
 Put invasive lines first
followed by induction..
Muscle relaxants :
 Sch- 1-1.5 mg/kg
MAINTAINENCEopioids,MR,inhalational
 Atra- 0.5- 1 mg/kg
 Vecu - 0.08-0.2 mg/kg  Opioids infusion ….
 Pancu- 0.08-0.15
fenta 0.1-0.5
mg/kg
 Rocu- 0.6 mg/kg
 Pipecuronium &
doxacurium longer
acting and provides
stable hemodynamics
thn pancuronium.
mcg/kg/min
Or small top ups of
fentanyl 50mcg every
30 min….
 Inhalational agentsisoflurane &
sevoflurane.
 Use gases to control
HTN response in pts
wid good LV fxn.
Intra-operative challenges :Haemodynamic changes related to heart
position:
 to visualize the coronary arteries surgeon may lift the
heart ( enucleation by pericardial stitches)or place
cotton mops or use tissue stabilizers (rocking
tech).The anesthetist shud anticipate these steps and
treat the resultant haemodynamic problems.
 For grafting of RCA & obtuse marginal branches
“verticalization” of the heart (posterior pericardial
stitches and a gentle retracting socket) is required.
 During grafting of RCA territory there can be
bradycardia. Treatment includes use of atropine and
atrial pacing if required.
1.
 During anastomosis / grafting of the circumflex Ar &
obtuse marginal artery heart positioning may result in
kinking or partial obstruction in the venous return &
right ventricle out flow obstruction, thus causing
hemodynamic compromise. Here, RV assist pump
devices can be used..to maintain hemodynamics.
Fig 4 The heart position using the technique of ‘rocking’ with a tissue stabilizer device.
Chassot P et al. Br. J. Anaesth. 2004;92:400-413
The Board of Management and Trustees of the British Journal of Anaesthesia
Hemodynamic alterations with cardiac
manipulation results from :1. In Vertical position the atrias are situated below the
corresponding ventricles, and the blood must flow up
into the ventricular cavities.
2. Pressure exerted by retractor on ventricular wall,
restricts local wall motion and decreases ventricular
dimensions.
3. Vertical position of heart distorts the mitral & tricuspid
valves, thus significant regurgitation may occur.
4. Surgical techniques- enucleation, heart rocking.
 Intraoperative hypotension shud b managed with
I.
Fluid therapy, leg elevation/trendelenberg positioning.
II. Vasopressor/Ionotropic support(maintain MAP > 70
mmHg )
III. ask surgeon to reposition cotton packs/ epicardial
stabilizers
IV. Intra aortic balloon pump support
V. Look for arrythmias and its causes & treat them

Fig 3 Modification of mitral shape with heart manipulation reconstructed in its
three‐dimensional aspect, as viewed from above (from reference 49, with permission).
Chassot P et al. Br. J. Anaesth. 2004;92:400-413
The Board of Management and Trustees of the British Journal of Anaesthesia
Intra-operative MI :SIGNS : increase in PCWP or appearance of new “v’ waves .(
less sensitive)
:SWMA on TEE
This can be avoided by :
 Maintaining MAP of at least 70mmHg.A mixed venous
oxygen saturation of at least 60% or more is suggestive of
adequate tissue perfusion.
 Reduction in myocardial oxygen consumption: by
avoiding tachycardia using intraoperative beta-blockers,
TEA or calcium channel blockers.
 Bradycardia may decrease cardiac output. It may be easier
and faster to correct bradycardia by electrically pacing the
patient.
 A certain degree of ischemia will occur during distal
anastomosis and can be prevented by using intraluminal
coronary shunts.
 PRECONDITIONING- volatile anesthetics such
as isoflurane or sevoflurane protect the
myocardium against ischemia by activation of a
preconditioning- like mechanism when
administered at 2 minimum alveolar
concentration (MAC) at least 30 min before the
ischemic insult.
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intraop Arrhythmias- cardiac displacement
increases the risk..especially reperfusion
arrhythmias…maintain potassium>4.5 ,
magnesium given after induction.
INDICATIONS FOR CONVERSION
TO CPB :Persistence of the followings for >15 min despite
aggressive therapy:
 Cardiac index <1.5 litre min–1 m–2
 SvO2 <60%
 MAP <50 mm Hg
 ST‐segment elevation >2 mV
 Large new wall motion abnormalities or collapse of
LV function assessed by TOE
 Sustained malignant arrhythmias
Fast track anesthesia: Tracheal extubation with in 8 hours, early
mobilization and early discharge from hospital.
 Pts not suitable for fast tracking:- bleeding,
dysrhythmias, hemodynamic instability.
 Benefits- economical, early regaining of cough
reflex thus lowers incidence of atelectasis,
pneumonia.
 To achieve early extubation,post op pain relief is
an imp consideraton.
Methods of post-op pain relief:
 i/v opioids
 Patient controlled analgesia
 Intercostal nerve block
 TEA
 Intrathecal opioids
 Intrapleural local anaesthesia.
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