Electrophysiology mapping is a medical technology used to study the heart’s electrical activity from the inside. It helps doctors find the source of arrhythmias, which are abnormal heart rhythms that can make the heart beat too fast, too slowly, or irregularly. By turning electrical signals into a 3D map, clinicians can see how activation spreads through the atria and ventricles.
This matters because precise mapping can guide treatment while reducing damage to healthy heart tissue.
During an electrophysiology study, thin catheters with electrodes are guided through blood vessels into the heart. The electrodes record voltage and timing data at many points, and software combines these measurements with position data to build a colored electrical map. Early activation, slow conduction, and abnormal circuits can appear as distinct regions on the map.
Physicians can then target these regions with ablation, pacing, or other therapies to restore a safer rhythm.
Key Facts
- Electrophysiology mapping records voltage and timing signals from electrodes placed inside or near the heart.
- Activation time is the time when a region of heart tissue depolarizes during a heartbeat.
- Conduction velocity can be estimated with v = distance / time.
- Heart rate is related to period by heart rate = 60 / T, where T is the time for one beat in seconds.
- Voltage maps help distinguish healthy tissue from scarred or low-voltage tissue.
- Ablation targets arrhythmia sources or pathways identified by the electrical map.
Vocabulary
- Electrophysiology
- Electrophysiology is the study of electrical activity in living tissues, especially the heart and nervous system.
- Arrhythmia
- An arrhythmia is an abnormal heart rhythm caused by disrupted electrical signaling.
- Catheter electrode
- A catheter electrode is a thin flexible medical tool that records or delivers electrical signals inside the heart.
- Activation map
- An activation map is a 3D display showing when different parts of the heart become electrically active.
- Ablation
- Ablation is a treatment that destroys or modifies small areas of heart tissue that cause abnormal rhythms.
Common Mistakes to Avoid
- Confusing an ECG with EP mapping is wrong because an ECG records electrical activity from the body surface, while EP mapping records detailed signals from many locations inside the heart.
- Assuming the brightest color always means the most dangerous region is wrong because map colors usually represent timing, voltage, or another chosen variable that must be read from the legend.
- Treating a 3D heart map as a picture of blood flow is wrong because EP maps show electrical activation patterns, not how blood moves through chambers.
- Ignoring units when calculating conduction velocity is wrong because distance and time must be in compatible units to get a meaningful speed.
Practice Questions
- 1 A signal travels 6.0 cm across heart tissue in 0.12 s. What is the conduction velocity in cm/s?
- 2 A patient has a heartbeat period of 0.80 s. Using heart rate = 60 / T, what is the heart rate in beats per minute?
- 3 An activation map shows one small atrial region activating earlier than surrounding tissue during each abnormal beat. Explain why this region might be considered a possible arrhythmia source.