Coronary Artery Bypass Grafting (CABG)
Cardiology,  Internal Medicine

Coronary Artery Bypass Grafting

The goal of CABG is to restore blood flow to the myocardium.

Preoperative Care

During preoperative assessment of patients undergoing coronary artery bypass grafting, special care should be paid to the severity of their coronary artery disease, their vascular function, the presence of comorbid disease, and explaining to the patient the procedure and postoperative care expectations.


Cardiac medications are to be continued up to the morning of the operation, except ACE inhibitors and digoxin.


Routine monitoring of CABG patients often includes:

5 lead ECG

Temperature – core temperature (nasopharyngeal)

Pulse oxymetry


Central venous pressure

Invasive BP monitoring

Anesthesia for CABG

An example protocol for induction: Etomidate, Fentanyl, and Rocuronium (muscle relaxant). For maintanence: an inhalational agent e.g. isoflurane or an infusion of propofol.

CABG operation

Coronary artery bypass grafting is an invasive procedure that require the chest to be opened. This is usually done by median sternotomy or another thoracotomy incision, and then the pericardium is incised. Caridopulmonary bypass (CBP) may be used and is stopped after the conduit has been grafted/ attached. The pericardium is left open until the patient is hemodynamically stabilized after which a closed water-seal chest drain is applied and the wound is closed.

Postoperative Care

Cardiovascular post-op complications include: hypotension (due to low CO or low SVR), hypertension, arrhythmias, conduction abnormalities and pulmonary hypertension.

Respiratory complications following CABG include atelectasis, penumothorax, hydrothorax, bronchospasm, and failure to wean from ventilator.

Conduits for CABG

Internal Mammary Arteries (aka Internal Thoracic Arteries as conduits

The internal mammary arteries, also called the internal thoracic arteries, are the most commonly used vessels for coronary artery bypass grafting. This is because of their excellent long term patency. Both the left and right internal mammary arteries have a patency greater than 90%, usually said to be 95%, at 15 years post operation.

The left internal mammary artery (LIMA) is the most commonly used source for grafting aka conduit. When right internal mammary artery (RIMA) is also used in addition to LIMA when bilateral grafts are needed. However, this can increase the risk of the sternum not healing properly. The RIMA is often used for occlusion of the right coronary artery (RCA), whereas the LIMA is often used for occlusion of the left anterior descending artery (LAD) as well as occlusion of the diagonal branch of the LAD and the left circumflex artery (LCX).

During harvesting, the entire LIMA is removed with only a small amount of tissue left at its origin at the subclavian artery. When grafted onto the LAD, the anastomosis is done either side-to-side or end-to-side.

Saphenous Veins as conduits

When multiple vessels are occluded/ severely stenosed, then the greater saphenous and lesser saphenous veins can be used. However, it has a lower patency rate long term, and is not an option in patients with venous insufficiency, arterial insufficiency or deep vein thrombosis because of concerns over healing of the harvesting site.

The gastroepiploic, inferior epigastric, and radial arteries are sometimes used as free grafts. Lastly, when there is no other conduit available, cryopreserved saphenous veins or umbilical vein allografts may be used, but they are last choice because of their poor patency.

Conduits (graft sources) for CABG

Graft source (conduit)Details
Left Internal Mammary Artery (LIMA)Best option with 95% patency rate at 15 years
Saphenous Veins25% patency at 10 years, 50% occluded, 25% stenosed
Right Internal Mammary Artery (RIMA)Similar patency rate to LIMA, used when both arteries are needed
Radial ArteryRisk of severe post-op vasospasm; patency 90% at 5 years
Right Gastroepiploic Artery90% patency at 5 years; use limited because artery is fragile, and technical issues
Inferior epigastric artery


Cover image from: staff (2014). “Medical gallery of Blausen Medical 2014“. 

WikiJournal of Medicine 1 (2). 


ISSN 2002-4436.