Minimally Invasive Cardiac Surgery

Conventional Cardiac Surgery have been performed world wide very successfully over past 50 Years.Introduction of Minimally Invasive (M.I.)techniques in Surgical specialities  brought Paradigm shift in decision making in Cardiac Surgery also.The Basic Principle of Minimally Invasive surgery is to avoid the Complications of ACCESS trauma(Surgical Entry wound).If Access Trauma can be reduced without compromising the efficacy of the procedure,Less Invasive operation will be successful.

MICS is not a single procedure, but refer to all procedures where full sternotomy is avoided. Various approachs used in MICS are-

•   RT/LT Mini thoracotomy –Direct Vision
•   Hemi/ Partial Sternotomy
•   Port Access surgery
•   Video Assisted thoracotomy (VATS)
•   Robotic Cardiac surgery(Da Vinci System)

MICS was introduced in1995 on this principle by Benetti et al in Brazil  .Firstly,MICS was done for Coronary Artery Bypass Surgery(CABG) and it was extend to Mitral valve(heart valve) surgery.  This development was possible due to

• Alternate Surgical Entry Wound
• M.I.Instrumentation-Special Long &double shafted instruments
• Endoscopic Tissue Retractor &/or Stablization system
• Surgical Optics-Endoscopic Visualization
• Advances in Perfusion technology Via alternate site

Routine Cardiac surgery is done by sternum (chest bone) split which involves about 12-15 cms incision.In MICS , approach is by 7-8 cms Chest incision on side.To work in little more depth,Special Chest wall retractor & Long Double Jointed Instruments are developed.Tissue Stablization or Retraction are achived by Endoscopic tissue stabilizer or Suction stabilization(Octopus).Optical visualization is achived by Telescopic camera .Improvement in perfusion technology have enable us to use Alternate Route of Femoral Vessels(groin area) for  Cardiopulmonary bypass.

Advantages of MICS

•   less post operative pain
•   Less post operative morbidity
•   better cosmetic scar
•   Shorter hospital stay
•   less workday loss

Anesthesia Protocols for MICS

•   Double lumen Endotracheal tube
•   Swan –Ganz cather( P.A. Line)
•   Percutaneous defibrillator pads
•   Patient postitioning with RT/LT tilting
•   TEE – very important role in Valve & ASD surgery especially for

              Guidewires & venous cannula placement

MICS basically includes five types of Cardiac surgery procedures

1. Minimally Invasive Coronary Surgery(MIDCAB)
2. Minimally Invasive Valve Surgery (MIVS)
3. Minimally Inavasive Atrial septal defect (ASD)
4. Endoscopic Vein Harvesting(EVH)
5. Min. Inv. Atrial fibrillation surgery

MIDCAB

Major contributory cause of problems in coronary surgery are due to

•  Entry Wound Trauma(Median Sternotomy)
• Systemic Effect of Cardiopulmonary Bypass
• Brain complication due Aorta manipulationThese problems are overcome in MIDCAB with use of Left small Thoracotmy(4^th ICS) as entry wound ,Aovidence of CPB & Minimizing aortic manipulation  .MIDCAB allows Arterial Grafting (LIMA) of Lt. Anterior Decending (LAD)very well.LIMA harvesting is done with special set of retractor system ( Thoracotrac ). Major problems in Multivessel MIDCAB are
•   Expsure of Posterolateral part of heart
•   Proximal anastmosis placement
•   Off or On pump surgery
•   Quality of anastmosis

 Extension of MIDCAB for Multi Vessel Grafting with different conduits(Radial or Saphenous) are being developed but long term results are awaited.

MIVS

Problems of Access Trauma was also the main factor for evolution of this technique.Mitral valve surgery is commonly done with Small Right Thoracotomy (via 4^th ICS)&Aortic valve surgery was done via Mini sternotomy Or RT Thoracotomy(3^rd ICS)  .Cardiopulmonary Bypass was achived by femoral vessels route & operation is performed with the help Long shaft instruments,Endoscopic visualization & Self Retaining Retractor system.Long term results are good & comparable to conventional surgery.

M.I.ASD Closure

ASD Closure is also done by Rt.Thoracotomy(4^th ICS).This procedure can be done comfortably by this approach.Cardio-pulmonary Bypass is achived by Central Cannulation(aortic & atiral) or peripheral cannulation(femoral vessels).Long term results are comparable with conventional surgery.

Endoscopic Vein Harvesting(EVH)

Saphaneous vein harvesting for CABG can be done in minimally invasive way with the use of special instrument set known as VASOVIEW (MAQUET).Long incision of leg can be avoided. This procedure requires two small incisions & have a steep learning curve. It consists of subcutaneous dissection of vein (Tunnelling) &division of the branches using electrocautery. So wound healing is faster with less complications.

Controversies

• Antegrade Vs. Retrograde perfusion

Problem of adequacy of body perfusion in case of small femoral artery is always present. Higher rate of Stroke(6.4%vs. 2.4%)in Retrograde perfusion in patients above 45 year is also a point for consideration.

• Aortic cross clamping

In earliar experience,Balloon clamp(endo clamp) was used .This had reported many aortic injuries. So transthoracic clamp have been used routine for cross clamping.

• Venous Cannulation

 Use of single two stage or double venous cannula is also a debatable aspect.

Contraindications

• Emergency surgery
• Haemodynamic unstability
• Morbid obesity
• Periferal vascular disease
• Sev AR(>3+)
• Sev COPD
• Spinal deformity
• LV dysfunction
• Pulmonary hypertension

Minimally Invasive Cardiac Surgery gaining popularity gradually.Long term outcome of MIVS are very good and comparable to routine procedure.Single vessel MIDCAB is very satisfactory.Early complication rates in term of Bleeding, Pain, Recovery & Hospital stay are much less with MICS.