Pacemakers and cardiac devices on chest X-ray

Written by the X-Ray Atlas editorial team from the sources listed below · Medical review pending · Updated 24 October 2026 · Level: Intermediate

Cardiac implantable electronic devices (CIEDs) include pacemakers, implantable cardioverter-defibrillators (ICDs), cardiac resynchronisation therapy (CRT) devices and implantable loop recorders. They are common on chest films, especially in older patients. The X-ray lets you identify the type of device, check that each lead tip is where it should be, and look for complications such as lead displacement, lead fracture or a pneumothorax after implantation. Device function is checked by interrogation and the ECG, not by the film, but the film often gives the first clue that something mechanical has gone wrong.

1. How to look

A PA and, where possible, a lateral film are the standard pair after implantation. The lateral is particularly useful because it separates anterior structures (the right ventricle) from posterior ones (the coronary sinus and its veins). Use a fixed order:

1. Generator: where is it? Usually below the left clavicle, in a subcutaneous or submuscular pocket, but right-sided and abdominal generators occur.
2. Count the leads and follow each from the generator, through the vein (usually the subclavian, axillary or cephalic), down the SVC and into the heart.
3. Find each tip and decide which chamber it is in.
4. Check continuity of every lead along its whole length, and the connection to the generator.
5. Compare with previous films. Lead displacement is often only obvious on comparison.
6. Look for complications: pneumothorax, effusion, and a change in the cardiac silhouette.

2. Lead positions

Lead	Frontal (PA) film	Lateral film
Right atrial (RA) lead	Usually in the right atrial appendage. Forms a J shape, curving upwards and medially at its tip, projected over the upper right heart.	Points anteriorly and upwards.
Right ventricular (RV) lead	Tip at the RV apex, projected over the left side of the heart just left of the spine near the diaphragm, or on the RV septum (more medial and higher).	Tip anterior, curving forward towards the sternum.
Left ventricular (LV) lead (CRT)	Enters the coronary sinus and runs up and to the left along the left heart border in a posterolateral cardiac vein.	Runs posteriorly, behind the heart.

3. Identifying the device

• Single-chamber pacemaker: one lead, usually in the RV.
• Dual-chamber pacemaker: two leads, one in the RA and one in the RV. This is the most common arrangement.
• ICD: recognised by a thick, dense shock coil on the RV lead. Some have a second coil higher up, in the SVC. The generator is often larger than a pacemaker's.
• CRT (biventricular) device: RA and RV leads plus an LV lead in the coronary sinus. A CRT device with a shock coil is a CRT-D; without, a CRT-P.
• Subcutaneous ICD (S-ICD): no leads in the heart. The generator lies in the left lateral chest wall, and a single lead runs under the skin along the left side of the sternum.
• Leadless pacemaker (for example Micra): a small capsule, about the size of a large vitamin pill, within the RV, with no generator in the chest wall.
• Implantable loop recorder: a small, thin device under the skin to the left of the sternum, with no leads. It records rhythm only.

Many generators have a radiopaque identifier code that the cardiology team can use to identify the manufacturer, which matters, for example, when a patient needs an MRI scan and the team must establish whether the system is MRI-conditional. That decision belongs to the cardiology and MRI teams, not to the film reader.

4. Complications

Early (after implantation)

• Pneumothorax: from subclavian or axillary vein puncture. Always check the apex on the side of the generator.
• Lead displacement (dislodgement): most common in the first weeks. The tip has moved from its previous position: for example, an RA lead that has lost its J shape, or an RV lead tip that has pulled back towards the tricuspid valve. Comparison with the post-implant film is the key.
• Perforation: the lead tip projects outside the cardiac silhouette, or beyond the epicardial fat. A new pericardial effusion (an enlarging, globular heart) should raise concern. Echocardiography or CT is used to confirm.
• Pocket haematoma: soft-tissue swelling around the generator; usually a clinical diagnosis.

Late

• Lead fracture: a break in the continuity of the conductor, often subtle. A classic site is between the clavicle and the first rib, where the lead is squeezed (the "subclavian crush" phenomenon). Zoom in and follow the lead closely through this region. The insulation can fail without a visible break, so a normal film does not exclude lead failure.
• Twiddler syndrome: the patient rotates the generator in its pocket, often unconsciously, which coils the leads around it and pulls them back from the heart. On the film the leads are twisted near the generator, and the tips have retracted, sometimes into the SVC or the brachiocephalic vein. A related "reel" variant rotates the generator on its long axis.
• Disconnection of a lead from the generator header.
• Abandoned leads: old leads left in place when a system is upgraded. They are cut and capped, and are not a complication in themselves, but they make the film harder to read.

5. Other things that look like devices

• Temporary pacing wires: a thin wire passed through a central vein to the RV, with an external pulse generator. Also epicardial pacing wires after cardiac surgery, which run from the anterior chest wall to the surface of the heart, often alongside sternotomy wires.
• Central lines and PICCs running alongside the leads. See central line and PICC position.
• Prosthetic heart valves and annuloplasty rings, and left atrial appendage occluders.
• ECG electrodes and leads on the skin surface: outside the body, and usually crossing the edge of the chest.
• Other implanted stimulators (for example vagus nerve or spinal cord stimulators) can sit in the chest wall, but their leads run to the neck or spine, not the heart.

Red flags: act now

What to focus on, by role

Role	Priorities
Medical student	Count the leads and name the device: single, dual, ICD (shock coil), CRT (coronary sinus lead). In an OSCE, mention the device in your "everything else" review.
Nurse	Know the patient has a device, report wound swelling and new symptoms, and check that a post-implant film has been reviewed for pneumothorax.
Junior doctor	Check the post-implant film for pneumothorax and lead position, and compare later films with it. Involve cardiology early for any change.
Radiographer	Include the whole generator and leads; a lateral is often part of the post-implant protocol.
Advanced / FRCR	S-ICDs, leadless devices, coronary sinus anatomy, subtle fractures, abandoned lead systems and MRI-conditional pathways.

See also: how to read a chest X-ray, heart failure and pulmonary oedema and the glossary.

Practise on lines and tubes films →

References

1. Aguilera AL, et al. Radiography of cardiac conduction devices: a comprehensive review. RadioGraphics 2011;31(6):1669–1682. pubs.rsna.org
2. Radiopaedia. Cardiac pacemakers. radiopaedia.org
3. Radiology Masterclass. Chest X-ray: lines and tubes. radiologymasterclass.co.uk

For education only. Not a substitute for a formal report, senior review or your local policy. Never use this page to make decisions about a real patient.