1. ANAESTHESIA FOR BEATING HEART SURGERY
MODERATOR- Dr Ajay Sood
PRESENTED BY- Dr Anupam

2. INTRODUCTION – OPCAB – performed first in 1964 CABG with CPB
The revival of OPCAB technique occurred in 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.

3. 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 mm hg..adv- it lifts than to compress heart.

5. 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 2- 3mg.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.

6. Heart is‘positioned’ by placing a few ‘mops’ underneath it
Heart is‘positioned’ by placing a few ‘mops’ 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.

7. 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

8. PROCEDURES PERFORMED ON BEATING HEART:-
Coronary artery bypass graft 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

9. PROBLEMS ASSOC WITH OPCAB:-
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

10. GOALS OF ANESTHETIC MANAGEMENT
Provision of safe anesthesia using a technique that offers max cardiac protection and stability.
Maintaining hemodynamics through out intra-operative period.
Allowing early extubation, ambulation.
Providing adequate pain relief.

11. MONITORING:
ECG: most imp monitoring. Stick ECG leads on the back 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

12. Intra arterial access-rt femoral preferred-coz 1st, it 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.

13. TEE- dcrsd accuracy bt still interpretable. causes of difficulty are…
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%
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)

14. 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.

15. 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.

16. 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

17. 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.

18. 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 mcg/ kg & sulfenta 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..

19. Muscle relaxants : MAINTAINENCE- opioids,MR,inhalational
Opioids infusion ….
fenta mcg/kg/min
Or small top ups of
fentanyl 50mcg every 30 min….
Inhalational agents- isoflurane & sevoflurane.
Use gases to control HTN response in pts wid good LV fxn.
Sch mg/kg
Atra mg/kg
Vecu mg/kg
Pancu mg/kg
Rocu- 0.6 mg/kg
Pipecuronium & doxacurium longer acting and provides stable hemodynamics thn pancuronium.

20. 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.

21. 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.

22. Fig 4 The heart position using the technique of ‘rocking’ with a tissue stabilizer device.
Fig 4 The heart position using the technique of ‘rocking’ with a tissue stabilizer device. The right ventricle is squeezed between the left ventricle and the right hemi‐sternum; the right ventricular outflow tract is compressed (courtesy of Medtronics™).
Chassot P et al. Br. J. Anaesth. 2004;92:
The Board of Management and Trustees of the British Journal of Anaesthesia

23. Hemodynamic alterations with cardiac manipulation results from :-
In Vertical position the atrias are situated below the corresponding ventricles, and the blood must flow up into the ventricular cavities.
Pressure exerted by retractor on ventricular wall, restricts local wall motion and decreases ventricular dimensions.
Vertical position of heart distorts the mitral & tricuspid valves, thus significant regurgitation may occur.
Surgical techniques- enucleation, heart rocking.
Intraoperative hypotension shud b managed with
Fluid therapy, leg elevation/trendelenberg positioning.
Vasopressor/Ionotropic support(maintain MAP > 70 mmHg )
ask surgeon to reposition cotton packs/ epicardial stabilizers
Intra aortic balloon pump support
Look for arrythmias and its causes & treat them

24. Fig 3 Modification of mitral shape with heart manipulation reconstructed in its three‐dimensional aspect, as viewed from above (from reference 49, with permission).
Fig 3 Modification of mitral shape with heart manipulation reconstructed in its three‐dimensional aspect, as viewed from above (from reference 49, with permission). (a) Normal saddle shape of the mitral ring when the heart is in its normal position. (b) When the heart is moved to the vertical position, the mitral ring is severely distorted. (c) When the lifted heart is rotated to gain access to the lateral wall, the ring is further folded and twisted.
Chassot P et al. Br. J. Anaesth. 2004;92:
The Board of Management and Trustees of the British Journal of Anaesthesia

25. 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.

26. 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.
intraop Arrhythmias- cardiac displacement increases the risk..especially reperfusion arrhythmias…maintain potassium>4.5 , magnesium given after induction.

27. 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

28. 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.

29. Methods of post-op pain relief:
i/v opioids
Patient controlled analgesia
Intercostal nerve block
TEA
Intrathecal opioids
Intrapleural local anaesthesia.

30. THANKS