Minimal invasive cabg

Minimal Invasive CABG
Technical Concepts and Results
Dr. Deep Chandh Raja.S

GOAL OF CABG
• Complete revascularisation of the area of
myocardium that is perfused by a coronary
artery with ≥50% stenosis (Hills et al. CIRCULATION 2011,
Practice guidelines)
• Conventional CABG  Median sternotomy
with help of cardio-pulmonary bypass
• Heart-Lung machine with Cardioplegic cardiac
arrest

OUTLINE
• BASIC CONCEPTS IN CABG- Conduits, Heart Lung
Machine, Cardioplegia
• Demerits of conventional CABG
• Introduction of OPCAB
• Various terminologies-
OPCAB, MIDCAB, TECAB, PACAB
• Types of Minimal Invasive CABG surgery
• MIDCAB-techniques
• Trials with respect to OPCAB/MIDCAB vs
Conventional
• Short views on PACAB, TECAB, HYBRID CABG

Basic Surgical Process of CABG
• Graft Harvesting – LIMA, LSVG, RIMA, Radial A.
• Heparinization
• Cardioplegia
• CPB Cannulation
• Distal Anastomosis (Snaring & shunting)
• Proximal Anastomosis
• Reversal of Protamine
• Decannulation
• Maintenance of normothermia, graft patency,
coagulation

CONDUITS IN CABG
• ARTERIAL
LIMA, RIMA, RADIAL
ARTERY, GASTROEPIPLOIC
ARTERY, INFERIOR
EPIGASTRIC ARTERY,
SPLENIC ARTERY
• VENOUS  SAPHENOUS
VENOUS

PATENCY RATES OF CONDUITS
1 year 10 years
SVG 80-90%
(2%/yr upto 5 yrs.)
50%
(5%/yr upto 10 yrs.)
LIMA 98%
(93-98% depending on
type of CABG))
>90%
Other arterial grafts 90% 60%
* Chikwe J, Beddow E, Glenville B. Cardiothoracic Surgery. Oxford: Oxford University Press; 2006

DETERMINING FACTORS FOR GRAFT
PATENCY
• Venous vs Arterial- SVG not suited for high shear
stresses of arterial circulation
• Type of arterial grafts- LIMA vs other grafts
Muscular arteries-Radial, Epigastric,
Gastroepiploic
• Target vessel- <70% stenosis in the native vessel
acts as a competitive supply to the target region
leading to graft atrophy and occlusion, hence
arterial grafts not used for these purposes
ARTERIAL GRAFTS HAVE POOR PATENCY IF USED TO GRAFT RCA WITH
<90% STENOSIS CLASS III

LIMA- A Unique Conduit !!
• RESISTANT TO ATHEROSCLEROSIS nearly
continuous elastic lamina, release of
prostacyclins, high eNO activity, platelet
inhibitors
• Less muscular than other comparable graft
vessels
• Parent origin from SCA, no need for proximal
anastomosis
• Good length
CONTRAINDICATION FOR LIMA HARVEST:
1.Lt. SCA stenosis
2.Poor LIMA flow
3.Emergency surgery
4.Radiation injury to LIMA

CARDIOPLEGIA
• Potassium rich solution with varying concentrations of
blood, nutrients, bicarbonate, buffers, electrolytes
• COLD 4 degree celcius
SIDE EFFECTS:
• Duration of cardioplegia α myocardial dysfunction
• Around 10-20% decline in myocardial function
immediate postop due to Myocardial edema,
Ischemia-Reperfusion injury
• HYPOTHERMIA induced release of cytokines post
perfusion

HEART LUNG MACHINE
• Blood comes in contact with tubings,
reservoirs, filters
• Form of artificial circulation in order to
maintain systemic perfusion
• Activation of complement system, leucocyte
activation, depletion of platelets, clotting factors
• Need for heparinisation ACT maintained
>400sec, 3mg /kg heparin

Mechanism of side effects in CABG
• Aortic manipulation (cannulation, clamp,
anastomosis)Micro and macroemboli (cholesterol)
• CPB microemboli (air, clots)
• CPB Complement activation (↑s100 beta)SIRS
(MODS-ARDS, AKI)
• CPB loss of platelets, coag. factors ↑ transfusion
of blood products and its inherent risks
• Microemboli Neurological adverse effects ranging
from stroke to cognitive dysfunction
• Large incision wound infection
Groom et al. Microemboli from cardiopulmonary bypass are associated with a serum marker of brain injury. J Extra Corpor Technol. 2010;42:40–4

COMPLICATIONS OF CABG
• Low Output syndrome: 4-9%, managed with
inotropes, IABP
• 1-5%- Myocardial Infarction
• 30% Arrythmias
• Adverse neurological outomes: 3%
Stroke:2-4%
Cognitive dysfunction: 40-60%
• Renal Injury-4%
• Transfusion
• Upto 2.9 % perop mortality, increases to 7.2%>80
years

Perioperative complication Isolated CABG(%)
Euro Heart Journal

OFF PUMP (BEATING HEART SURGERY -BHS)
• OPCAB- Off Pump CABg
• Majority of side effects of CABG specially
those related to CPB can be circumvented
• Innumerous trials and RCTs between OPCAB
and conventional CABG Debate continues
• Not immune to side effects, in fact has
created a new dimension of problems esp.
cardiac motion

New ventures
• Minimally invasive CABG problems of a
large incision can be overcome
• Space constraint, inaccess to posterior lateral
branches, incomplete revascularisation

Confusing Terminologies
• OPCAB
• MIDCAB
• PACAB
• TECAB
BEATING HEART SURGERY: OPCAB, MIDCAB, TECAB
MINIMAL INVASIVE SURGERY: MIDCAB, TECAB, PACAB

MINIMAL INVASIVE CABG
• MIDCAB
• PACAB
• TECAB
- MIDCAB & TECAB are OFF PUMP
- PACAB is ON PUMP
Definition- OFF PUMP CABG UNDERTAKEN WITHOUT A FULL MEDIAN
STERNOTOMY

INDICATIONS
• SINGLE VESSEL DISEASE (NonPTCAable)
• MULTI VESSEL DISEASE WITH HIGH PERIOP
RISK
• HYBRID PROCEDURES (MIDCAB to LAD + PTCA
to other vessels)

HIGH RISK CASES FOR CABG
• High risk of deep sternal wound infection
(e.g., diabetics, morbidly obese)
• Severely impaired left ventricular function
• Chronic kidney disease
• Significant carotid or neurological disease
• Severe aortic calcification
• Prior sternotomy, Redo CABG
• Elderly

TECHNIQUES IN MIDCAB
• EXPECTED PROBLEMS
• INCISION, POSITION
• INSTRUMENTATION
• STEPS

EXPECTED PROBLEMS
• BEATING HEART coronary motion, suturing
related complications
• INTERRUPTION OF CORONARY FLOW
regional ischemia, arrythmias
• COLLATERAL BLOOD FLOW hampers view
• MINIMAL ACCESS to posterior heart, PLVs, OM
vessels manoeuvring the heart in a small
space decreases SV significantly by ˜ 40%,
Incomplete revascularisation

ANSWERS TO THE PROBLEMS
ANSWERS
CORONARY MOTION MECHANICAL TISSUE
STABILISERS
INTERRUPTION OF
CORONARY FLOW
ARTERIOTOMY SEAL,
SHUNT, CANNULA
COLLATERAL BLOOD
FLOW
SALINE/ CO2 JET
MINIMAL ACCESS APICAL STABILISATION,
ROBOTS, HYBRID

POSITION AND INCISION
• 15-30° Right lateral position
• 5-7 cm incision: 4th
, 5th
ICS
• LAST- left anterior small thoracotomy
• Multiple small incisions may be taken for
access to other sites- like subxiphoid incision
for PDA

Deep Pericardial Traction Sutures

MICS RETRACTOR SYSTEM (THE BOW)

MECHANICAL TISSUE STABILISERS
• OCTOPUS™
• PLATYPUS™
• IMMOBILISER™
Immobilises the target area of interest:
- Evidence suggests better anastomotic results
than the prestabilisation device use era
- Class 1 Indication for performing MIDCAB

LAST
Lt.Pleural cavity opened, left lung
deflated, LIMA skeletonised
Pericardium opened,
Deep pericardial traction sutures paced
Saline sprayer,OCTOPUSArteriotomy
Intracoronary shunts
Anastomoses with continuous
polypropylene sutures
Lt.Pleural/pericardial drain placed

LIMITATIONS
• Not more than 2 coronary arteries can be
grafted (At present)
• Anastomotic site occlusion was frequent in
the earlier daysREINTERVENTIONS
• Severe LV dysfunction surgeons prefer on
pump CABG inspite of high risks

CONTRAINDICATIONS
• Small target vessels
• Calcified target vessels
• Diffusely diseased target vessels
• Intramyocardial target vessel
• Emergency cases
• Patients with hemodynamic instability

CABG MIDCAB
INCISION MIDLINE 10-15 cm 5 cm
HEART-LUNG MACHINE + -
TECHNIQUE Less complex Steep learning curve
MORTALITY RATES SIMILAR SIMILAR (DEBATE !)
GRAFT PATENCY GOOD LESSER
REVASCULARISATION COMPLETE INCOMPLETE
REPEAT PROCEDURES LESS FREQUENT
TRANSFUSIONS MORE LESS
RECOVERY & LENGTH OF
STAY
DELAYED & LONGER QUICKER & SHORTER

TRIALS
• Innumerous observational studies (cases
series/nonrandomised comparison) published
• Few RCTs and Meta analyses
• POEM STUDY 2001
• ROOBY TRIAL 2009
• CORONARY METAANALYSES 2012
• Perioperative mortality 2.5% comparable to 2.9%
in conventional CABG

POEM STUDY
• 165 MIDCAB vs 145 onpump
CABG
• Comparable LIMA patency
rates (96.5% in MIDCAB
vs97.6%) at 1 yr
• Comparable MACCE rates
• Advantages of MIDCAB-
lesser duration of hospital
stay, lesser transfusions
*Mehran et al. CTT 2000

ROOBY TRAIL
• Largest RCT to date (Randomised On/Offpump
Bypass trial)
• ˜2200 pts.
• Neuropsychological outcomes similar in both
groups
• MACE rate lesser and graft patency rate better
in ON PUMP conventional CABG

Results
• There was no significant difference between
off-pump and on-pump CABG in the rate of
the 30-day composite outcome (7.0% and
5.6%, respectively; P = 0.19).
• The rate of the 1-year composite outcome
was higher for off-pump than for on-pump
CABG (9.9% vs. 7.4%, P = 0.04).
• Patients with fewer grafts completed than
originally planned was higher with off-pump
CABG than with on-pump CABG (17.8% vs.
11.1%, P<0.001).

CRITICISM OF ROOBY TRIAL
• 99% Males
• Low risk group
• MIDCAB most suited for High risk patients
where a difference in outcomes can be
demonstrated

• Meta-analyses of 59 trials involving 8961 pts
– reduction in early strokes with off-pump
– no differences in other major CV outcomes.
CORONARY INVESTIGATION
OUTCOMES
44

OFF-PUMP
(n = 2375)
%
ON-PUMP
(n = 2377)
%
p value
Any Blood Transfusion 50.7 63.3 <0.001
Antifibrinolytics 26.1 37.0 <0.001
Re-operation for bleeding 1.4 2.4 0.02
Peri-operative Transfusions and
Bleeding
45

1st
Co-Primary Outcome (30 Days)
46
Off Pump
%
On Pump
%
Hazard
Ratio
95% CI
p
value
Primary Outcome
Death, Stroke, MI, Renal Failure
9.8 10.3 0.95 0.79-1.14 0.59
Components
Death 2.5 2.5 1.02 0.71-1.46
Stroke 1.0 1.1 0.89 0.51-1.54
Non Fatal MI 6.7 7.2 0.93 0.75-1.15
New Renal Failure 1.2 1.1 1.04 0.61-1.76

Other Outcomes at 30 days
47
Off Pump
%
On Pump
%
Hazard
Ratio
95% CI p value
Angina 0.1 0.1 1.50 0.25-8.99 0.66
PCI 0.5 0.1 3.67 1.02-13.2 0.05
Re-do CABG 0.2 0.04 6.00 0.72-49.8 0.01
PCI/Re-do CABG 0.7 0.2 4.01 1.34-12.0 0.01
All re-operations (re-do CABG) 3.3 3.9 0.85 0.63-1.14 0.27
All re-operations/Re-do CABG/PCI 3.7 4.0 0.94 0.70-1.25 0.65

Off Pump
%
On Pump
%
Relative
Risk 95% CI p value
Respiratory Infection or
failure
5.9 7.5 0.79 0.63-0.98 0.03
Acute Kidney Injury
AKIN Stage 1 28.0 32.1 0.87 0.80-0.96 0.01
RIFLE risk 17.0 19.6 0.87 0.76-0.98 0.02
New Renal Failure requiring
Dialysis
1.2 1.1 1.04 0.61-1.76 0.77
Other Outcomes at 30 days
48
Acute Kidney Injury Network (AKIN): absolute increase in serum creatinine value ≥27 µmol/L
OR an increase of ≥150 % from the baseline serum creatinine value
Risk, Injury, Failure, Loss and End-stage Renal Disease (RIFLE): increase of ≥150 % from the
baseline serum creatinine value

• At 30 days there was no difference in the
primary outcome between Off pump CABG and
On pump CABG (9.8% vs. 10.3%, p=0.59).
• Off-pump was associated with:
–Less transfusions and re-operation for bleeding
–Less acute kidney injury
–Less respiratory infections/failure
–More early revascularizations
Conclusions
49

Early Cognitive Dysfunction
• Reference: Assessment of neurocognitive impairment
after off-pump and on-pump techniques for coronary
artery bypass graft surgery: prospective randomized
controlled trial. Zamvar V, Williams D, Hall J, et al. BMJ
2002;325:1268-1273.
• Message: neurocognitive impairment more in
ONPUMP CABG.
One week postop, 27% in the off-pump and 66% in the
on-pump had neurocognitive impairment (P=0.004).
Ten weeks postop, 10% of the off-pump and 40% of
the on-pump had neurocognitive impairment
(P=0.017).

Early Stroke
• Reference: Safety and efficacy of off-pump coronary
artery bypass grafting. Arom KV, Flavin TF, Emery RW,
et al. Ann Thorac Surg 2000;69:704-710
• Message: Several postoperative events are studied
• Of Interest: There were no significant differences in
the number of patients who suffered from
neurological deficits such as permanent stroke (2.0 %
on-pump versus 1.4 % off-pump, p=0.42) and transient
ischemic attack (0.9 % on-pump versus 0.3 % off-
pump, p=0.35)

CONFLICTING EVIDENCE
AUTHOR et al YEAR FAVOURS
Athanasiou 2004 Less stroke MIDCAB
Moller 2010 NO diff. in MACCE
Eifert 2010 NO diff. in MACCE
Jensen 2008 NO diff. in MACCE
Mack 2004 Lesser stroke MIDCAB
• All observational studies/ retrospective analyses
from registries
• No RCTs in High risk groups

2011 GUIDELINES (AHA STATEMENT)
“ BOTH CONVENTIONAL CABG AND MIDCAB HAVE SIMILAR
OUTCOMES AND NONE HAS SUPERIORITY OVER THE
OTHER”
• Periop STROKESIMILAR in both
• MIDCAB advantageslesser neurocognitive dysfunction,
lesser renal dysfunction, lesser duration of hospital stay
• CONVENTIONAL CABG advantages lesser complexity,
better access to posterolateral wall complete
revascularisation
• Decision left to the surgeon to individualise the decision of
minimally invasive off pump vs conventional cabg in a given
patient

PTCA VS MIDCAB
(esp. for PLAD)
• Buszman et al. JACC 2011
• Around 200 pts. In each arm
• NO short (30days) / Long term (5yrs.)
differences in MACE rates
• ↑ short term adverse events like wound
infection, low output syndrome, bleeding in
MIDCAB
• ↑ long term repeat revascularisations in PCI
arm (72% IInd generation DES used)

HYBRID PROCEDURES
• BEST OF BOTH WORLDS
• Advantages of MIDCAB ( minimally invasive, off
pump, long term patency of LIMA)
• Advantages of PTCA (difficult to approach vessels
like LCX)
• NO TOUCH AORTIC surgeries
CLASS I INDICATIONS FOR MIDCAB/HYBRID:
Calcified proximal aorta
Unfavourable LAD/ Distal LM for PCI
Lack of conduits for grafting
Poor nonLAD targets for CABG which are amenable to PCI

STAGED HYBRID
• SINGLE need for HYBRID suites for both
procedures to be done in same sitting
• 2 STAGED CABG f/b PCI within 36 hours
• UNIQUE CHALLENGES !!

MINIMALLY INVASIVE CABG
• MIDCAB
• PA CAB
• TECAB

PACAB
• PumpAssisted minimal incision CAB-ON PUMP
• Femoral CBP & Endoaortic clamp
• Only advantages of a minimal incision
– Surgeons in the early phase of MICS experience
– Before advent of tissue stabilisers

TECAB
• Totally Endoscopic CABG
• Robotic assisted anastomoses
• Early graft failure, reinterventions, CABG
conversion rates
• At present, comparison of TECAB vs
conventional CABG is lacking

MIDCAB vs PACAB vs TECAB
(Jegaden et al. JCTS 2011. Retrospective analysis)
• Early postop results • Follow-Up results

TAKE HOME MESSAGES
• Beating heart surgery- OPCAB
• OPCAB + MINIMAL INVASIVEMIDCAB
• Other minimal invasive surgeries: PACAB,
TECAB
• OPCAB vs ONPUMP CABG: none superior
• HYBRID CVR- promising concept with
collecting evidences and new challenges
• HIGH RISK CABGMIDCAB may be considered

Minimal invasive cabg

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