What is the detailed procedure for open coronary heart surgery?

Detailed Procedure of Open Coronary Heart Surgery

The standard open coronary artery bypass grafting (CABG) procedure is performed via median sternotomy with cardiopulmonary bypass, using the left internal mammary artery as the primary conduit for the left anterior descending artery to improve long-term outcomes. 1

Preoperative Assessment and Preparation

• Comprehensive cardiac evaluation is essential to identify patients with ischemic heart disease, heart failure, or valvular disease that may affect surgical outcomes 1
• Antiplatelet medications should be managed appropriately before surgery:
  • Clopidogrel and ticagrelor should be discontinued at least 5 days before elective surgery 2
  • Prasugrel should be discontinued at least 7 days before surgery 2
  • For urgent cases, these medications should be discontinued for at least 24 hours 2
• Aspirin (100-325 mg daily) should be administered preoperatively 2

Surgical Approach and Setup

• The procedure is typically performed through a full median sternotomy, which provides complete access to the heart and great vessels 1
• Approximately 70% of CABG operations worldwide use extracorporeal circulation (cardiopulmonary bypass) 1
• Transesophageal echocardiography (TEE) is recommended for monitoring ventricular function, regional wall motion, and valvular function during surgery 1

Step-by-Step Surgical Procedure

1. Access and Exposure

   • After sterile preparation, a midline incision is made from the sternal notch to below the xiphoid process 1
   • The sternum is divided with a saw, and a sternal retractor is placed to expose the heart and mediastinum 1

2. Conduit Harvesting

   • The left internal mammary artery (LIMA) is harvested from the chest wall while still attached proximally 1
   • Additional conduits may include:
     • Saphenous vein grafts harvested from the leg
     • Radial artery from the non-dominant arm
     • Right internal mammary artery in selected cases 1

3. Cardiopulmonary Bypass Establishment

   • The pericardium is opened to expose the heart
   • Cannulation sites are prepared:
     • Ascending aorta for arterial return
     • Right atrium or both venae cavae for venous drainage 1
   • Systemic heparinization is administered
   • Cardiopulmonary bypass is initiated after achieving adequate anticoagulation 1

4. Myocardial Protection

   • The ascending aorta is cross-clamped
   • Cardioplegia solution is delivered (antegrade via aortic root and/or retrograde via coronary sinus) to arrest the heart and provide myocardial protection 1
   • Systemic hypothermia may be employed to further protect organs 1

5. Distal Anastomoses

   • Target coronary arteries are identified beyond their stenoses
   • Arteriotomy is performed on each target vessel
   • Distal anastomoses are created using continuous polypropylene suture or interrupted silk sutures 1
   • The LIMA is typically anastomosed to the LAD artery first, as this is the most critical graft 1

6. Proximal Anastomoses

   • For vein or free arterial grafts, proximal anastomoses are created on the ascending aorta
   • These may be performed during cross-clamp or with a partial occlusion clamp after the cross-clamp is removed 1

7. Completion and Closure

   • After all anastomoses are completed, the cross-clamp is removed allowing reperfusion
   • The heart is gradually weaned from cardiopulmonary bypass
   • Protamine is administered to reverse heparin
   • Temporary pacing wires and mediastinal/pleural drains are placed
   • The sternum is closed with stainless steel wires
   • Soft tissues and skin are closed in layers 1

Alternative Techniques

• Off-pump coronary artery bypass (OPCAB) may be performed without cardiopulmonary bypass using stabilizing devices to immobilize the target area of the beating heart 2
• Minimally invasive direct coronary artery bypass (MIDCAB) uses smaller incisions for selected cases 2
• Hybrid coronary revascularization combines LIMA-to-LAD grafting with percutaneous coronary intervention (PCI) of non-LAD vessels and may be reasonable in patients with:
  • Heavily calcified proximal aorta or poor target vessels for CABG
  • Lack of suitable graft conduits
  • Unfavorable LAD artery for PCI due to excessive tortuosity or chronic total occlusion 2

Outcomes and Complications

• Early clinical outcomes at 3 months after CABG include:
  • 1-2% mortality rate
  • 1-2% morbidity rate for each of: stroke, renal failure, pulmonary failure, cardiac failure, bleeding, and wound infection 1
• Hospital mortality is higher for urgent procedures, patients with left main stenosis, or diabetes 1
• Potential complications include:
  • Myocardial infarction (2.4% incidence) 3
  • Stroke, particularly in patients with diseased ascending aortas 1
  • Bleeding requiring reoperation
  • Wound infections
  • Atrial fibrillation 1

Special Considerations

• In patients with recent myocardial infarction, CABG mortality is elevated for the first 3-7 days after infarction 1
• Techniques that minimize aortic manipulation may reduce neurological complications in patients with diseased ascending aortas 1
• Perioperative beta-blockade should be carefully managed to avoid hemodynamic instability 1