Electrophysiology studies examine the electrical activity of the heart muscle. They are used for the diagnosis and treatment of heart conditions that affect the heart’s electrical activity.
Over the years, electrophysiology methods have developed to become less invasive by utilizing imaging modalities like computed tomography (CT) and magnetic resonance imaging (MRI). Over time, advances in imaging techniques have been made simultaneously with progress in electrophysiological procedures. Today, cardiac electrophysiology can provide electrical information about the epicardial surface of the heart non-invasively.
In this article, we outline the traditional electrophysiology techniques, before comparing them with today’s technology.
Traditional electrophysiology techniques
Electrophysiology techniques can be used to assess different conditions, mainly relating to heart arrhythmias. These typical electrophysiology techniques include:
Electrocardiogram
An electrocardiogram (EKG) records the heart’s electrical signals. It is a quick and painless procedure that is used for the detection of heart problems and the monitoring of heart health.
Electrocardiograms can be used to identify or detect; coronary artery disease, arrhythmias, how well heart disease treatments are working, and if a patient has previously had a heart attack.
Implantable loop recorder
An implantable loop recorder is a heart monitoring device. It can record the heart rhythm continuously, for a period of up to three years, allowing your heartbeat to be monitored. An implantable loop recorder is typically recommended for people with arrhythmias, syncope, or who have had an unexplained stroke. An accompanying transmitting device will be provided to the patient.
Holter monitor
A Holter monitor is a wearable device that tracks the heart rhythm. It is worn for one or two days and allows a doctor to monitor the heartbeats of a patient. Holter monitor tests are typically ordered when an EKG cannot provide sufficient information. Using information from the Holter monitor, a doctor can diagnose arrhythmias. If arrhythmias can’t be detected, a monitor to be worn over a longer period – such as an implantable loop recorder – may be recommended.
Holter monitor tests are usually advised for patients that have arrhythmia symptoms or syncope (unexplained fainting). It may also be recommended for patients who have heart conditions that increase their chances of having an arrhythmia.
Pre-procedure imaging for the EP lab
Modern-day electrophysiology uses CT and MRI imaging to provide a reconstructed volume of the heart, displaying fibrosis of the heart, and adjacent anatomies. This volume is then imported into the electrophysiology (EP) lab and synchronized with the volume created by the electroanatomical mapping system located in the EP lab, which includes electrical information. The name of this non-invasive functional imaging modality is pre-procedure imaging (CT and MRI) for the EP lab.
For many clinicians, integrating CT and MRI imaging into the EP workflow has proven beneficial to pre-planning procedures in patients with conditions such as congenital heart disease. The ADAS 3D software platform is designed to support this technique, enabling the use of pre-procedural planning to complement electro-anatomical mapping in the EP lab. Using ADAS 3D, LV/LA fibrosis and LV wall thickness and display surrounding anatomical structures can be quantified.
Traditional ECG techniques vs pre-procedure imaging for the EP lab
How do traditional electrocardiology (ECG) techniques – such as EKGs, implantable loop recorder, and Holter monitor – compare with the modern-day pre-procedure imaging for the EP lab technique?
Simply put, pre-procedure imaging for the EP lab goes beyond what traditional ECG techniques are capable of. The main limitation of traditional techniques is that they offer electrical signals on the surface of the body; a significant distance away from the heart.
These signals record the electrical activity of the heart remotely, and consequently, with low resolution. Today’s technology provides a way to examine geometrical properties and discover the origin of arrhythmias.
Pros and cons of pre-procedure imaging for the EP lab
What are the advantages and drawbacks of pre-procedure imaging for the EP lab?
Pros
- Non-invasive
- Can accurately determine the exact location of the corridor within the endo-to-epi space
- Translates LGE MR into 3D visualizations to quantify and understand fibrosis
- Identifies LV Fibrotic corridors automatically
- Converts CTA images into 3D LV wall thickness images
- Provides the ability to see the myocardium in layers being able to display the structure of the scar tissue from endo to epi
- It displays LV/LA adjacent anatomy (coronaries, aorta for the LV, pulmonary veins, esophagus, phrenic nerve for the LA for example)
Cons
- Endocardial potentials reconstruction requires a degree of knowledge that may not be available in clinic
- Can only provide imaging of the fibrosis or thickness of the tissue
- Does not identify electrical information or provide electrical mapping
Conclusion
It is clear to see why the modern-day, technological world may favor pre-procedure imaging for the EP lab. The advances in accuracy presented by pre-procedure imaging for the EP lab make it a valuable tool that offers many more diagnostic possibilities than traditional ECG tools.
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Sources:
https://cardiacrhythmnews.com/stepping-beyond-ecg-electrocardiographic-imaging