Dr. Luc Tambeur Coronary artery bypass grafting CABG - OPCAB

Coronary artery disease  Definition:  Narrowing of the coronary arteries  Caused by thickening and loss of elasticity of the arterial walls  Limiting blood flow to the myocardium  Flow reserve (effort)  At rest  Occlusion

Coronary artery disease  Morphology and processes:  Focal intimal accumulation of lipids, blood elements, fibrous tissue, calcium etc. with associated changes in the media  → Plaque  → Stenosis  Regression of plaque and collateral formation  Plaque rupture and thrombosis  Usually affects multiple coronaries simultaneously, proximally and at bifurcations

Myocardial infarction  Imbalance between oxygen supply and demand  Myocardial necrosis starts after 20 minutes  Border zone  Reperfusion within 3-4 hours can limit the extent of myocardial necrosis  Scarring. LV systolic and diastolic dysfunction. Chronic heart failure.

Diagnosis  Symptoms: Angina pectoris, acute myocardial infarction, chronic heart failure, sudden death, incidental finding on ECG  Noninvasive tests to identify and quantify CAD and sequelae: ECG, CXR, Labs, Exercise testing, Nuclear scans, Echocardiography, CT (Ca ++ )

Diagnosis  Associated conditions  Atherosclerosis: carotids, PAD  Definitive diagnosis: extent, distribution and severity of anatomic coronary artery disease  Coronary angiography  New modalities: CT (MRI)

Coronary angiography  Grading of stenoses:  Moderate: 50% diameter = 75% cross- sectional area loss  Severe: 67% diameter = 90% cross- sectional area loss  Distribution:  Single system / two system / three system  Left main

Coronary anatomy

Indications for surgery  Comparative benefit of surgery relative to no treatment / medical treatment / PCI  Enormous variability in CAD, impacting on risk calculation → patient-specific predictions  General indications:  Left main or left main equivalent  3 system disease  2 system disease with severe prox. LAD and LVEF < 50% or ischemia on non-invasive testing  1 or 2 system disease with large area of viable myocardium and high-risk criteria

Bypass grafting  Full sternotomy and CPB (HLM): CABG  Full sternotomy, no CPB: OPCAB  Small sternotomy, parasternal access, thoracotomy, with or without CPB: e.g. MIDCAB

Bypass grafting  CABG = Golden standard and still most widely used (STS database ± 80%)  Objective: complete revascularisation by bypassing all severe stenoses in all affected coronary branches with ≥ mm diameter  Most widely used conduits: LIMA, RIMA, SVG, radial artery, gastro-epiploic artery

Conduits LIMA / RIMA

Conduits SVG

Conduits Radial

Conduits Gastro-epiploic

Conduit configurations

Endarter- ectomy

CABG  Median sternotomy  Conduit harvesting  Heparin, cannulation and CPB with mild to moderate hypothermia  Cross-clamping of the aorta and cardioplegia  Distal anastomoses. Rewarming started.  Cross-clamp removed. Proximal anast. using a partially occluding clamp. Clamp removed. De-airing.  CPB discontinued, cannulae removed, protamine.  Pacing wires, drainage tubes, hemostasis and closure.

CABG

OPCAB  Attempt to maintain normothermia  Median sternotomy  Conduit harvesting  Heparin. Pacing wires.  Maneuvers to maintain hemodynamic stability (Trendelenburg, table, R pleura,.)  Pericardial sling  Luxation. Stabilisation. Distal anastomoses with or without shunting.  Proximal anastomoses. Protamine.  Chest drains. Hemostasis. Closure.

Not discussed  IABP and other support devices  Emergency surgery  Redo surgery  Other modalities of bypass grafting: MIDCAB, robotic surgery, …  Adjunctive surgical treatment: TMLR, growth factors, cell transplantation  Combined surgery

Results  Early mortality can be predicted, using risk stratification models (Euroscore, STS)  Time-Related Survival, generally:  1 month: 98%  1 year: 97%  5 year: 92%  10 year: 81%  15 year: 66%  NB: ± 25% of early and late deaths are not related to CAD or CABG

Time-Related Survival

Results  Freedom from angina: 60% at 10 years  Freedom from AMI: 86% at 10 years  Freedom from sudden death: 97% at 10 years  80% of patients are working 1 year postop.  Graft patency:  LIMA (to LAD) ± 90% at 10 and 20 years.  Radial artery ± 80% at 7 years  Gastro-epiploic artery ± 60% at 10 years  SVG ± 50-60% at 10 years, 80% to LAD