11.3 Pacemakers, ICDs, Holter Hookup & Other Special ECG Considerations
Key Takeaways
A pacemaker spike is a sharp vertical line; a ventricular spike followed by a wide QRS shows capture.
A pacing spike that is not followed by a P wave or QRS complex suggests failure to capture and must be reported immediately.
Turn on the ECG machine's pacemaker detection setting and do not place an electrode directly over the implanted generator.
A patient who reports an ICD shock is reported to the nurse right away; repeated shocks are an emergency.
Holter electrodes go on the chest over bony areas such as the sternum and ribs, after careful skin prep, with lead wires looped and taped to prevent pulling.
Pacemakers, ICDs, Holter Hookup & Other Special ECG Considerations
NCCT's ECG content includes adapting technique to patients with special considerations (for example, amputee, pacemaker), accounting for special considerations during troubleshooting (for example, hair, pacemaker/AICD), and placing electrodes appropriately for the test (for example, 12-lead, Holter, telemetry). Section 11.2 covers 12-lead placement and amputees, and Section 12.4 covers telemetry placement and Holter patient education. This section fills in implanted cardiac devices, other special situations, and the Holter hookup itself.
Implanted Cardiac Devices
Ask every patient whether they have a pacemaker or implanted defibrillator before recording an ECG. Most devices sit under the skin below the left collarbone (sometimes the right), with leads running into the heart.
| Device | What It Does |
|---|---|
| Pacemaker | Senses the heart's own rhythm and sends electrical impulses when the heart is too slow or pauses |
| Implantable cardioverter-defibrillator (ICD or AICD) | Detects dangerous fast rhythms such as ventricular tachycardia or fibrillation and delivers pacing or a shock; most ICDs also pace |
Reading Pacemaker Spikes
- A pacing spike is a sharp, narrow vertical line on the ECG.
- Atrial pacing: a spike right before the P wave.
- Ventricular pacing: a spike right before a wide QRS complex, because the impulse starts in the ventricle rather than traveling through the normal conduction pathway.
- Dual-chamber pacing: spikes before both the P wave and the QRS.
| Finding | Meaning | PCT Action |
|---|---|---|
| Spike followed by a P wave or QRS | Capture (the heart responded) | Normal paced rhythm; label the tracing |
| Spike not followed by a P wave or QRS | Failure to capture | Check the patient and report immediately |
| No spikes when the heart rate falls below the set rate | Possible failure to pace | Check the patient and report immediately |
| Spikes landing in the wrong place, such as on T waves | Possible sensing problem | Report |
The PCT recognizes and reports; the nurse and provider interpret and manage the device.
Recording an ECG on a Patient With a Device
- Turn on the ECG machine's pacemaker detection or enhancement setting, if it has one, so pacing spikes print clearly and are not filtered out or mistaken for artifact.
- Do not place an electrode directly over the generator. Move the electrode slightly to a nearby spot, keeping placement as close to standard as possible, and note the change.
- Label the tracing "pacemaker" or "ICD" so the reader expects the spikes and the wide paced complexes.
- Keep magnets away from the device; placing a magnet over it changes how it works and is done only by licensed staff for specific reasons.
When an ICD Fires
- A patient may describe a shock as a sudden "kick" or "punch" in the chest.
- Anyone touching the patient during a shock may feel a tingle, which is not dangerous to staff, especially with gloves on.
- Report any shock to the nurse right away, stay with the patient, and check responsiveness and breathing. Repeated shocks or a shock followed by chest pain, fainting, or unresponsiveness is an emergency. If the patient becomes pulseless, start CPR and use the AED as usual, avoiding pad placement directly over the device.
Daily Living Questions Patients Ask
Manufacturers generally advise keeping cell phones and headphones with magnets at least about 6 inches (15 cm) from the device, walking through store and airport security gates at a normal pace rather than lingering, and telling every provider about the device before an MRI or procedure. Refer detailed questions to the nurse or cardiology team.
Other Special Considerations
| Situation | Adaptation |
|---|---|
| Heavy chest hair | Clip the hair at the electrode sites (do not shave with a razor unless policy allows), then clean and dry the skin |
| Sweaty (diaphoretic) or oily skin | Dry the skin, clean with alcohol, let it dry, and use electrodes designed to stick to moist skin |
| Tremor or Parkinson's disease | Move limb electrodes closer to the torso, keeping them symmetric (Section 12.4) |
| Patient cannot lie flat | Record in semi-Fowler's position and note it on the tracing (Section 11.2) |
| Burns, wounds, or casts | Use the nearest intact skin at a symmetric site on both limbs |
| Children | Use pediatric electrodes, keep the child warm and calm (a parent can help), and remember that normal heart rates are higher in children |
| Seizure during recording | Stop the recording, protect the patient, call for help, and repeat the ECG later |
Holter Monitor Hookup
A Holter monitor records the heart rhythm continuously, usually for 24 to 48 hours, while the patient goes about daily life. Hookup quality decides whether the whole recording is usable.
- Verify the order and identify the patient, explain the purpose, and ask about devices and skin allergies.
- Prepare the skin meticulously: clip hair, clean each site with alcohol, let it dry, and lightly abrade it. Poor prep is the main cause of noisy, unreadable Holter data.
- Place electrodes on the chest over bony areas, such as the sternum and ribs, rather than over large muscles, which reduces motion artifact. The exact positions follow the monitor's diagram; common systems use 3 to 7 electrodes.
- Attach the lead wires, make a small stress loop in each wire, and tape it so movement does not tug the electrodes.
- Check the signal on the recorder or its app to confirm a clean tracing on each channel.
- Record the start time and make sure the recorder's clock is correct, because the patient's diary entries are matched to that clock.
- Give the patient the diary and instructions (Section 12.4): record activities and symptoms with exact times, continue normal activities, protect the recorder from water, and return at the scheduled time.
Patch Monitors and Event Recorders
- Adhesive patch monitors stick to the upper left chest and record a single channel for up to about 14 days. Many patches allow brief showers, so follow the specific device's instructions rather than the traditional Holter rules.
- Event and loop recorders store the rhythm when the patient presses a button during symptoms or when the device detects an abnormal rhythm. They are useful when symptoms happen less often than once or twice a day.
Clinical Trap: The Invisible Spikes
A PCT records a 12-lead ECG on a patient with a pacemaker without turning on the machine's pacemaker setting and places the V2 electrode over the generator pocket. The tracing shows wide QRS complexes with no visible spikes, and the reader worries about a new bundle branch block. Asking about devices, enabling pacemaker detection, moving the electrode off the generator, and labeling the tracing would have prevented the confusion.
A PCT is preparing to record a 12-lead ECG on a patient who has a pacemaker. Which actions are correct?
Place the V2 electrode directly over the generator to capture the device signal
Remove the pacemaker magnet from the crash cart and place it over the device
Turn on the machine's pacemaker detection setting, keep electrodes off the generator, and label the tracing
Record the ECG with the patient standing to reduce pacing spikes
A telemetry strip for a patient with a ventricular pacemaker shows regular pacing spikes, but several spikes are not followed by any QRS complex. What does this suggest?
Failure to capture, which should be reported immediately
Normal ventricular capture
Somatic tremor artifact that needs no action
A properly functioning dual-chamber pacemaker
Where should Holter monitor electrodes generally be placed to produce a clean recording?
Over the large muscles of the upper arms and thighs
Directly over the breast tissue so the wires are hidden
On the abdomen below the umbilicus
On the chest over bony areas such as the sternum and ribs, after careful skin prep, with wire loops taped down
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