A resting ECG is the standard of care for the initial assessment of many heart conditions — and it may be the most important thing you do for your patients in a day. It’s imperative that everyone involved in your ECG workflow is aware of and compliant with the key fundamentals. If overlooked, the data captured by your ECG could be impacted, with consequences for resulting interpretations, diagnoses and patient treatment plans.
When was the last time you reexamined how you prepare for and conduct ECG exams to ensure the best possible outcome? If it’s been a while, here are some factors to consider that could be impacting your results.
An ECG is only as good as the waveform acquired. That’s why each aspect of the exam is important, even down to how the electrodes themselves are handled and applied. A dry electrode with inadequate gel can reduce conduction of the ECG signal, compromising the data acquired. In most instances, this is simply the result of improper storage and can be easily avoided by following manufacturer’s instructions and these simple guidelines:
In addition to proper storage, the type of electrodes used during an exam can make a difference — not all electrodes can be used with all ECG devices. Some tips to keep in mind are:
High-quality ECG waveforms require good practices when prepping the patient and placing electrodes. Even for the most experienced clinicians, periodically reviewing best practices is worthwhile. If proper techniques have not been followed, ECG interpretation may be compromised before it even begins. Following these guidelines for patient prep consistency can help minimize motion and electrostatic artifact. It can also help ensure accuracy and comparability between traces done at different times, or across facilities.
Patient preparation best practices:
Taking just a few extra moments for patient prep can lead to higher quality exams the first time. Proper electrode placement is also critical, as even the slightest deviation from the correct position can create clinically significant changes.1 Improperly placed electrodes can potentially lead to mistaken interpretation, misdiagnosis of conditions and mismanagement of patient care.2
When it comes to an inaccurate ECG interpretation, the top factor cited is precordial electrode misplacement.2 According to the ACC and AHA, 5% of all ECGs performed are done with a lead reversal.3 Some lead reversals can be difficult to discern as an error and may lead to physicians incorrectly identifying arrhythmia where there is none.4
Make sure to review proper electrode placement. Many manufacturers include visual placement guidelines right on the device.
An ECG signal can be interrupted by various types of “noise,” producing artifacts that could impact the quality of your ECG data. Let’s review some types of signal interference to be aware of:
Electromagnetic interference (EMI)
Electromagnetic interference (EMI) is a consequence of the growing use of smartphones and wearable devices such as smart watches and activity trackers. A review of clinical literature on this topic shows that:
To avoid this form of artifact, make sure the patient and anyone else present removes and turns off these electronic devices.
External forces such as movement from nearby construction have been hypothesized to cause signal interference.
ECG interpretation depends on the quality of the data captured, not just the skill of the practitioner reading the data. Some factors that have a critical impact on the data captured include filtering and sampling. With a better understanding of these factors and their implications, you can take appropriate steps to achieve ECG results you can trust for diagnosis and treatment decisions.
ECG filtering removes noise from ECG recordings. In so doing, it’s intended to help physicians see waveform data more clearly, making ECGs easier to read and interpret. Filters can be very beneficial, if set to an appropriate threshold, and if the interpretive algorithm still looks at the original versus the processed waveform.
While filtering can yield a clean-looking ECG, too much filtering can distort or remove authentic waveform data. The problem with overly filtered ECGs is that you may not know what you’re missing. Physicians need to be aware of the filtering that takes place on any given ECG, and its potential impact on the interpretation.
Governing bodies like the ACC, AHA and HRS publish adult and pediatric guidelines to:
An ECG is really just a visual representation of the electrical activity of the heart. The electrical stimulus of the heart occurs continuously and in a repeated pattern to make the heartbeat. To accurately represent this activity in digital form, a resting electrocardiograph is tasked with collecting enough data points to reproduce the analog signal as close to the original as possible.
The rate at which these data points are sampled can have a significant impact on ECG waveforms that have fast-moving or high-frequency components. Some examples of high-frequency information include:
The data captured by your ECG directly impacts the resulting interpretations, diagnoses and patient treatment plans. Whether you are involved in ECG acquisition or interpretation, spending a little more time considering these critical factors can help improve the accuracy of the data collected and the resulting ECG interpretation.