03 / Cardiac Surgery · open
Coronary artery bypass grafting
New plumbing around blocked coronaries: conduit from the chest wall and leg, grafted onto the arteries beyond their disease, classically on a heart stopped and lent to a machine.
Indication: Left main or three-vessel coronary disease, and diabetics with multivessel disease, where surgery outlives stenting.
Read the imaging first
Practice before you scrub
Read the coronary angiogram
A 68-year-old with diabetes and exertional angina despite medical therapy. Coronary angiography is performed. (Fictional educational case.)
- Proximal LAD and left main disease pull hardest toward CABG: the muscle at stake is the argument.
- A lesion is only bypassable if the vessel beyond it is worth sewing to: the surgeon reads targets, not just narrowings.
The anatomy the operation is built on
On the tray for this operation
Test yourself on the tray
Stage
1 / 4
Sternotomy and conduit harvest
Median sternotomy; the left internal mammary artery is taken down from the chest wall while the saphenous vein is harvested from the leg.
Watch for: Sternal malunion or deep sternal wound infection · Conduit injury during harvest
Why are we operating?
CABG re-plumbs the heart's own blood supply: conduits carry blood past blocked coronaries so whole territories are revascularised at once. It is considered when disease is too proximal, too diffuse or too important for stents, classically left main disease, proximal LAD disease, multivessel disease, and the diabetic patient with several territories at risk.
Pulls toward surgery
Gives the team pause
The conduits
LIMA (internal thoracic artery)
Harvested from the underside of the chest wall, left attached at its origin.
The gold-standard graft: an artery that stays open for decades, classically sewn to the LAD.
One per side and it is precious; injuring it during harvest costs the operation its best conduit.
Saphenous vein
Harvested from the leg, then reversed so its valves do not block flow.
Long, available and forgiving: the workhorse for the remaining targets.
A vein living an artery's life: graft disease over years is its known weakness.
Radial artery
The non-dominant forearm, after confirming the ulnar can carry the hand.
An arterial alternative for high-grade lesions, where competitive flow will not shut it.
A muscular artery that spasms: it dislikes moderate lesions with competing native flow.
Shared foundations
What the surgeon is thinking
Sternotomy and conduit harvest
Why harvest the conduits before opening the pericardium?
The operation's clock is the bypass and clamp time, so everything that can happen off the clock does: conduits are prepared while the heart is still working for itself, often two teams at once, chest and leg.
Cannulation, bypass, arrest
Why are we going on bypass at all?
A beating, blood-filled heart is a moving target with a knife-hostile surface. Bypass hands the circulation to the machine; the cross-clamp and cardioplegia then buy a still, protected field measured in borrowed minutes.
The anastomoses
Why does the LIMA go to the LAD?
The LAD feeds the largest territory a single vessel owns, and the LIMA is the graft with the longest patency. Marrying the best conduit to the most important target is the single decision with the most future in it.
Weaning and closure
Why is the TEE checked before leaving the OR?
Weaning is an exam the heart sits under ultrasound: new wall-motion abnormality asks whether a graft is working, and residual air or a struggling ventricle is far cheaper to fix now than in the ICU an hour later.
Decision points
Which conduit for a tight proximal LAD lesion?
LIMA
The default marriage: best conduit, most important target.
Saphenous vein
Works, but spends the durable option's advantage on the wrong target.
Radial artery
Reasonable arterial alternative when the LIMA is unavailable.
Targets are ranked by the muscle they feed, conduits by how long they stay open; the operation pairs them in that order.
The heart will not separate from bypass: what categories does the team run?
Rhythm
Pace it, or fix what broke it: potassium, ischaemia, the clamp's cost.
Preload
An empty ventricle cannot eject; filling is the cheapest inotrope.
Contractility
Inotropes, and the question they imply: is a graft down?
Afterload
A vasoplegic circulation after bypass needs a vasoconstrictor, not more volume.
Weaning failure is approached as physiology, not panic: rhythm, preload, contractility, afterload, and the TEE arbitrating between them. A new regional wall-motion abnormality moves the conversation to the grafts.
Leaving the OR
The handoff
- Procedure
- CABG x3: LIMA-LAD, SVG-OM1, SVG-PDA
- Bypass time
- 94 min
- Cross-clamp
- 61 min
- Events
- Weaned on low-dose noradrenaline; TEE satisfactory
- Lines & drains
- Mediastinal + left pleural drains, atrial and ventricular pacing wires
- Watch for
- Drain output hourly, rhythm, lactate clearance
A fictional educational patient, handed over the way real ones are.
The postoperative course
- ICU arrivalSedated and ventilated; the first hours are drains, pressures and rewarming.
- POD 0-1Extubation, pressors weaning, drains slowing; the tachycardic board that still needs reading.
- POD 2-3Drains and wires out as criteria allow; the classic window for post-operative AF.
- POD 4-6Ward mobilisation, sternal precautions taught, secondary prevention started in earnest.
- DischargeHome with a healing sternum and a medication list that is half the operation's long-term benefit.
Watch it done
Cardiopulmonary bypass: the role of the circuit
Why the operation needs a machine at all: a still, bloodless heart with the body still perfused.
Source: CTSNet · Watch on YouTubeCardiopulmonary bypass: the circuit
The path blood takes from the venous cannula through the reservoir, oxygenator and pump back into the aorta.
Source: CTSNet · Watch on YouTubeCardiopulmonary bypass: circuit components
Each part of the circuit named and explained: cannulae, reservoir, pump heads, oxygenator, filters and suckers.
Source: CTSNet · Watch on YouTubeCardiopulmonary bypass: pathophysiology
What non-pulsatile flow, haemodilution, hypothermia and the foreign circuit do to the body, and why the ICU course follows.
Source: CTSNet · Watch on YouTubeCardiopulmonary bypass: conduct and weaning
Going on, running the pump, and the choreography of coming off: rewarming, rhythm, filling and the cannulae out.
Source: CTSNet · Watch on YouTubeCardiopulmonary bypass: emergency scenarios
What goes wrong on the pump and what the team does in the first minute: air, dissection at the cannula, pump failure, oxygenator failure.
Source: CTSNet · Watch on YouTubeCoronary artery bypass surgery
Sternotomy, conduit, bypass and the grafts, in the words of the centre that does the most of them.
Source: Cleveland Clinic · Watch on YouTube