Optical coherence tomography (OCT): a Cath Lab 101 guide

Reviewed by Rodnie Oro, cath lab charge nurse · Last reviewed: October 2026 · Education only, not medical advice

OCT in one minute

What it is: light-based imaging on a catheter that shows the inside of a heart artery in very fine detail.

Who it is for: people having an angiogram or PCI where the team needs detail on plaque, stent size or expansion.

Main risks: the risks of the angiogram or PCI, plus a small extra amount of contrast and rare artery injury.

Usually: a few extra minutes during an angiogram or PCI.

On this page: What is OCT? · Who is it for? · When is it done? · Step by step · Recovery · Risks · Kit list · First time in the lab? · FAQ

What is OCT?

OCT uses near-infrared light rather than sound.

• a thin imaging catheter is passed over the guidewire
• contrast is flushed briefly to clear blood
• the catheter is pulled back quickly, recording detailed pictures

OCT shows fine detail of the artery surface, plaque and stent struts.

New to the acronyms? See the Cath Lab Abbreviations A–Z.

Who is it for?

It may be considered for people with:

• planning and sizing a stent
• checking stent expansion and position
• understanding plaque in heart attacks
• investigating stent failure

The decision is made by your heart team, who will talk through the reasons, the alternatives and the risks with you.

When is it done?

It can be planned in advance or done urgently. Before it, you usually have:

• blood tests, including kidney function and blood count
• an ECG, and often an echo or other scan
• a review of your medicines, especially blood thinners and diabetes medicines, as per centre protocol
• a chance to ask questions and give consent

Step by step

1. Getting ready

You lie on the X-ray table. The wrist (or groin) is numbed with local anaesthetic. ECG, blood pressure and oxygen levels are monitored. You may be given medicines to thin the blood, as per centre protocol.

2. Access

A sheath is placed in the radial artery at the wrist or the femoral artery in the groin, sizes per device and operator. A guide catheter is placed at the opening of the coronary artery and heparin is given, dose as per centre protocol. A thin guidewire is passed across the narrowing.

3. Imaging run

• A. Wire. A guidewire is placed in the artery.
• B. Catheter. The OCT catheter is advanced beyond the area.
• C. Flush and pull. Contrast clears blood during the fast pull-back.
• D. Measure. The team measures and plans.

Most people don't feel the imaging or measurement.

4. Finishing

A final angiogram checks the result. The sheath is removed and the wrist closed with a pressure band, or the groin with pressure or a closure device, per device and operator.

Recovery and aftercare

• After the procedure: recovery depends on the main procedure (usually an angiogram or PCI).
• Going home: often the same day.
• Results: the images are stored and used to guide treatment.
• Medicines: take your blood thinners exactly as prescribed; don't stop them without talking to your heart team.
• Activity: avoid heavy lifting with the treated arm or leg for a few days.

Call 999 if you have chest pain, breathlessness, fainting, signs of a stroke, or heavy bleeding or swelling at the access site.

Risks and complications

Your team will explain the risks that apply to you. Possible problems include:

• the risks of the angiogram or PCI it is part of
• artery spasm, usually relieved with medicines
• artery tear or blockage (rare)
• rhythm disturbances (rare)

Cath lab kit list (printable)

Barts example kit list

An example from one UK centre, written generically. Every lab has its own protocol, and sizes and doses vary.

• radial or femoral arterial sheath, size per device and operator
• guide catheter, shape per operator
• coronary guidewire, per operator
• Y-connector and flush set
• heparin, as per centre protocol
• OCT catheter and console, per device and operator
• contrast for flush, volume as per centre protocol
• nitrate, as per centre protocol

Procedural steps (Barts example)

• Wire; nitrate
• OCT catheter beyond target
• Guide engaged; flush with pull-back
• Measurements
• Treatment decision

First time in the cath lab?

💡 First-time tip

• Good engagement. The guide must be well seated for the flush.
• Flush ready. Prepare the injector.
• Kidney function. Note contrast totals.
• Save runs. Label each run.

FAQ

Does OCT use X-ray?

No; it uses light.

Does it use more dye?

A little, for flushing.

Will I feel it?

Usually not.

Related Cath Lab 101 guides

• PCI (coronary angioplasty and stents)
• Coronary angiogram
• Chronic total occlusion (CTO PCI)
• Cath Lab Abbreviations A–Z

Sources

All checked on 10 October 2026. Each page's own date is shown where it gives one.

• Knuuti J, et al. 2019 ESC Guidelines for the diagnosis and management of chronic coronary syndromes. Eur Heart J 2020;41(3):407–477. PubMed 31504439
• Byrne RA, et al. 2023 ESC Guidelines for the management of acute coronary syndromes. Eur Heart J 2023;44(38):3720–3826. PubMed 37622654
• StatPearls (NCBI Bookshelf), search: optical coherence tomography coronary. ncbi.nlm.nih.gov/books

Disclaimer

Education only. This page is for general education for healthcare students, cath lab staff and curious readers. It isn't medical advice and doesn't replace advice from your own doctor, heart team or local unit protocols. Equipment and medicines are described generically. No product or manufacturer is recommended. If you think someone is having a heart emergency, call 999.

Disclosure: I work for a company that makes a device used in this procedure. This page is independent education, isn't sponsored or reviewed by any company, and doesn't recommend any product.

All diagrams on this page are original illustrations created for rodnieoro.com.