8 Factors That Can Interfere With an ECG Reading

The ECG is an essential tool for diagnosing and monitoring cardiac conditions, in both human and veterinary medicine. By recording the heart's electrical activity, it lets clinicians spot irregularities that may point to cardiovascular disease.

Even so, a number of factors can interfere with ECG results, undermining the accuracy of the data and the reliability of the diagnosis.

In this article we walk through the situations most likely to affect an ECG reading and how to make the results more dependable.

Why the ECG matters

The electrocardiogram (ECG) is a non-invasive test that records and tracks the heart's electrical activity. In veterinary medicine it is central to diagnosing cardiac disease, monitoring cardiovascular status in emergencies, and assessing the heart before surgical procedures.

These recordings are key to identifying arrhythmias, ischemia, conduction disturbances, and other conditions that, left untreated, can seriously threaten the animal's health.

Beyond diagnosis, the ECG also plays a crucial role in prevention and treatment follow-up, allowing the veterinarian to track the patient's response and fine-tune the therapeutic approach as needed.

When is an ECG ordered?

In veterinary practice an ECG is ordered in a range of situations, including:

Pre-anesthetic assessment: before surgery the ECG helps confirm the patient is fit for the procedure, lowering the risk of complications.

Diagnosis of arrhythmias and cardiovascular disease: it reveals irregularities in heart rate and rhythm.

Monitoring in emergencies: it gives a fast read on a patient's cardiac status in critical situations.

Follow-up of cardiac treatment: the ECG helps track the response to therapy and guide any adjustments.

8 factors that can interfere with an ECG reading

Accurate as it is, the ECG can still be thrown off by several factors, leading to incomplete or even mistaken diagnoses. Below are the situations that most often interfere with the reading:

1. Incorrect electrode placement · Poorly placed electrodes can distort the electrical signals picked up, producing inaccurate readings. The ECG requires the electrodes to sit at specific points on the animal's body so the heart's electrical impulses are captured correctly. Keep in mind that the ECG should ideally be performed with the patient in right lateral recumbency. If another position is used, the reading clinician must be told which one.

2. Patient movement · Involuntary movements such as tremors or spasms can disturb the captured signals, adding noise and making the trace harder to interpret. In many cases the patient needs to stay completely still during the exam to ensure accuracy.

3. Poor electrode contact · When the electrodes do not make good contact with the patient's skin, the electrical signals are not transmitted effectively, leading to incomplete or incorrect recordings. Cleaning the area properly and applying conductive gel are essential steps to ensure solid contact.

4. External electrical interference · Nearby electronic equipment, such as monitors and anesthesia machines, can generate electromagnetic interference that distorts the ECG signal. Running the exam in a space free of electronics, or moving the equipment away from the patient, helps minimize this effect.

5. Breathing or physical exertion during the exam · Changes in the patient's breathing, or panting, can affect the reading, since chest movement alters the signals picked up by the electrodes. To avoid this kind of interference, the patient should be at rest before the exam.

6. The patient's body position · The patient's position during the exam can also affect the results. Shifts in posture can interfere with the captured signals, especially in animals that are not used to staying still or holding a specific position.

7. Rusty alligator clips or worn springs · Alligator clips that are worn, rusted, or have lost spring tension can compromise electrode contact and produce inconsistent readings. Routine equipment checks help prevent mechanical problems.

8. Patient anxiety or stress · Stress can raise the heart rate and alter ECG results. Proper handling techniques and a calm environment are essential to ease the patient's anxiety and ensure a more accurate exam.

How to ensure a quality ECG

A few practices help ensure the ECG delivers more reliable, accurate data. Here are some of them:

Equipment maintenance: regular servicing and care of the ECG device and accessories prevent malfunctions and ensure better signal capture.

Team training: a well-trained team is essential to run the exam correctly and to handle any interference. Technical know-how on applying and reading the ECG makes the exam more effective.

Up-to-date equipment: modern devices, such as high-definition ECG models, are more accurate and less prone to interference. Today's technology also adds features like data recording and integration with telemedicine systems, streamlining patient follow-up.

A suitable exam environment: a space free of noise and electronic interference supports accurate ECG data. Rooms set up for exams reduce distractions and lower the chance of electrical interference.

Reliable, practical veterinary ECG

To make the ECG both practical and reliable, INpulse offers advanced equipment that adds confidence to the diagnosis. INcardio X, INcardio Agile, and INmonitor are among the solutions designed to deliver precision and patient comfort while making the work easier for the veterinary team.

Built on the latest technology, these devices provide accurate data and support detailed patient monitoring, paving the way for faster, more effective diagnoses.

For more on how to optimize the ECG and to explore other solutions for your practice, browse our content on veterinary electrocardiography and veterinary telemedicine in the clinic.