When you hear about coronary artery bypass grafting (CABG), you may come across terms such as internal mammary artery graft, radial artery graft and saphenous vein graft. These are the three main types of blood-vessel conduits commonly used to create bypasses around blocked coronary arteries.
Strictly speaking, CABG itself is not divided into only three types. The procedure can also be described according to the number of bypasses performed or how the surgery is carried out. However, when patients ask about the “three types of CABG,” they are often referring to the three commonly used graft sources.
If you are learning about bypass surgery more broadly, you can also explore our guide to Coronary Artery Bypass Grafting (CABG).
The three main graft types used in CABG
During CABG, the surgeon needs a healthy blood vessel that can be used to create a new route for blood flow. This vessel is called a graft or conduit.
The three commonly discussed options are:
- Internal mammary artery graft
- Radial artery graft
- Saphenous vein graft
Each has different characteristics, and the choice depends on the patient's coronary anatomy, age, other medical conditions, the location of the blockage and the surgeon's assessment.
*AI-generated image - for illustration only. Clinical accuracy is not guaranteed.
1. Internal mammary artery graft
The internal mammary artery, also called the internal thoracic artery, runs along the inside of the chest wall. The left internal mammary artery (LIMA) is particularly important in CABG.
When the left anterior descending (LAD) coronary artery requires bypassing, the left internal mammary artery is generally the preferred conduit because of its strong long-term performance.
Instead of completely removing the artery, surgeons can preserve its original blood supply at one end and connect its other end to the coronary artery beyond the blockage. This allows blood to flow through the graft into the heart muscle.
Why is the internal mammary artery commonly preferred?
Arterial grafts have structural characteristics that make them well suited to long-term use in coronary bypass surgery. The left internal mammary artery, in particular, has demonstrated excellent long-term patency when used to bypass the LAD.
2. Radial artery graft
The radial artery is located in the forearm and is another arterial conduit that can be used for CABG. Because the radial artery is an artery rather than a vein, it is naturally exposed to higher blood pressure and can provide good long-term graft performance in appropriately selected patients.
Is everyone suitable for a radial artery graft?
No. The surgeon needs to make sure that using the radial artery will not compromise blood flow to the hand.
The circulation between the radial and ulnar arteries is assessed before the artery is harvested. Doctors also consider whether the patient has kidney disease that may eventually require dialysis and whether the radial artery has previously been used for catheter-based procedures.
For example, current guidance advises avoiding use of the radial artery as a bypass conduit in patients with chronic kidney disease who have a high likelihood of progressing rapidly to haemodialysis.
3. Saphenous vein graft
The saphenous vein is located in the leg and has historically been one of the most commonly used vessels for CABG. A section of the vein is harvested and used to create a new route between the circulation and a coronary artery beyond its blockage.
Because veins normally carry blood at lower pressure than arteries, saphenous vein grafts do not have the same long-term durability as the best-performing arterial grafts. Nevertheless, they remain extremely useful in CABG because they are readily available, versatile and can be used to bypass multiple coronary vessels.
Saphenous vein grafts are commonly used for coronary territories such as the right coronary and circumflex systems, depending on the patient's anatomy and the surgeon's strategy.
Why are vein grafts still used if arterial grafts can last longer?
A CABG operation may require several bypasses, and there may not be enough suitable arterial conduits to graft every target vessel. The saphenous vein provides a practical and versatile option for additional bypasses.
The choice also depends on the patient's age, kidney function, diabetes status, target-vessel anatomy, expected longevity and risk of complications from harvesting additional arteries.
Therefore, using a vein graft does not mean that the surgery is inferior. It means the surgeon is selecting the most appropriate combination of conduits for that individual patient.
How are the three grafts different?
| Graft type | Where it comes from | Typical role | Key feature |
|---|---|---|---|
| Internal mammary artery | Inside the chest | Frequently used for the LAD | Excellent long-term performance |
| Radial artery | Forearm | Often used for an important non-LAD coronary vessel | Good long-term patency in appropriate patients |
| Saphenous vein | Leg | Frequently used for additional coronary targets | Versatile and readily available |
Does the type of graft affect how long a bypass lasts?
Yes. The type of conduit can influence long-term graft patency, which means how well the graft remains open and allows blood to flow over time.
Arterial grafts generally have better long-term patency than saphenous vein grafts. This is one reason modern CABG strategies often aim to use arterial conduits when appropriate.
However, graft longevity depends on more than the type of blood vessel. The severity of the blockage in the target coronary artery, the quality of the blood vessel, patient factors and long-term cardiovascular risk management can all influence outcomes.
Are there different numbers of CABG bypasses?
Yes. This is where another common source of confusion comes in. You may hear terms such as:
- Single bypass – one coronary artery is bypassed
- Double bypass – two coronary targets are bypassed
- Triple bypass – three coronary targets are bypassed
- Quadruple bypass – four coronary targets are bypassed
Are there also different ways of performing CABG?
Yes. CABG can also be classified according to how the operation is performed. The two broad approaches are:
On-pump CABG
In conventional or on-pump CABG, a heart-lung machine temporarily takes over the heart's pumping and oxygenation functions while the surgeon performs the bypass operation on a relatively still heart.
Off-pump CABG
In off-pump CABG, the surgeon performs the bypasses while the heart continues beating. Special stabilising equipment helps keep the area being operated on sufficiently steady.
*AI-generated image - for illustration only. Clinical accuracy is not guaranteed.
These are different surgical techniques rather than different graft types. The choice depends on the patient's anatomy, medical condition and the surgeon's experience.
How does the surgeon decide which graft to use?
There is no single graft combination that is right for every patient. The surgeon considers:
- Which coronary arteries need bypassing
- The location and severity of the blockages
- The quality and size of the target coronary arteries
- The patient's age and expected longevity
- Diabetes and other medical conditions
- Kidney function
- The condition of the potential graft vessels
- Previous procedures involving the arteries that might be harvested
- The risk of wound or other complications
Can more than one type of graft be used in the same CABG operation?
Yes. It is very common for surgeons to use a combination of conduits. For example, a patient may receive a left internal mammary artery graft to the LAD, a radial artery graft to another important coronary artery and one or more saphenous vein grafts for additional targets. The combination depends on the number and location of coronary blockages and the patient's suitability for each type of conduit.
The Bottom Line
When people refer to the “three types of CABG,” they are usually talking about the three main types of blood-vessel grafts used during bypass surgery: the internal mammary artery, radial artery and saphenous vein.
The internal mammary artery, particularly the left internal mammary artery, is especially important for bypassing the LAD. The radial artery can provide a durable arterial graft for suitable non-LAD targets, while the saphenous vein remains a versatile option for additional bypasses.
There is no single combination that is best for every patient. Surgeons select the grafts according to the coronary arteries that need bypassing, the patient's anatomy, age, medical conditions and long-term treatment goals.
*AI-generated image - for illustration only. Clinical accuracy is not guaranteed.
It is also important to distinguish graft type from number of bypasses. A single, double, triple or quadruple bypass describes how many coronary targets are bypassed—not which type of graft is used.
