Operative Technique

Surgical Anatomy of the Heart

Access to heart

• Harvesting of Long saphenous vein
• chest opened via sternotomy + LIMA dissected from chest wall
• Heart cannulated via ascending aorta + right atrium before cardiopulmonary
• Longitudinal arteriotomy made beyond narrowing of coronary vessel + distal anastamosis is performed
• Application of aortic cross clamping prevents blood flow down coronary arteries (but increases risk of ischaemia)
• Patient re-warmed, clamps removed, heart re-perfused

Selection of Conduit

• Venous Grafts:
  • Long saphenous vein (10 year patency rate 50-60%)
  • short saphenous vein
  • cephalic vein
• Arterial Grafts:
  • Left internal mammary artery (internal thoracic artery) - conduit of choice for LAD (10 year patency rate 90%)
  • Radial artery -NB Allen's test to ascertain collateral circulation

Pre-operative workup

• ECG
• Echocardiography
• Carotid duplex study
• Pulmonary function tests
• Angiography
• FBC, U+Es, LFTs, Clotting, G+S

• Antibiotics: Cefuroxime 1.5g +/- Vancomycin

Post-op management

• Prophylactic chest drain
• External cardiac pacing

Complications

Bleeding
3-5% of patients.
May develop tamponade / hypotension
Medical management first
May require emergency re-sternotomy

Management of Bleeding:

Check coagulation profile
Fibrinogen
Platelets

Specific treatments:

1. Protamine sulphate
   • Directly binds to heparin and inactivates
2. Trasylol / Aprotin 2MU iv
   • (Bovine) serine protease inhibitor (specifically trypsin, chymotrypsin, plasmin, kallikrein)
   • Effect on Kallikrein: inhibits formation of factor XIIa and plasmin - slows down fibrinolysis
3. Tranexamic acid
   • Inhibits activation of plasminogen into plasmin

Arrythmias
Common to develop ST / AF

Management of Tachyarrythmias

1. Correct potassium >4.5mmol/l - Potassium chloride
2. Correct magnesium: 8/10-20mmol MgSO4 IV

Atrial Flutter

1. Vagal manoeuvres
2. Adenosine 6mg/12mg/12mg
3. B-blocker rate control
4. DC synchronised cardioversion

Atrial Fibrillation

1. B-blocker iv / Digoxin 500mg iv/12'
2. Amiodarone 300mg iv/1' + 900mg iv/23'
3. DC synchronised cardioversion

Management of Bradyarrythmias

1. Atropine 500mcg iv bolus (repeat to maximum of 3mg)
2. Adrenaline 2-10mcg/min
3. Cardiac pacing