Electrophysiology – EP Study and RF Ablation
Study of the electrical activity of the heart (or any other organ). Strictly speaking, study of the electrical activity of the heart should be called cardiac electrophysiology.
When is electrophysiology study (EP study) advised?
Study of the electrical activity of the heart is recommended in electrical disorders of the heart. It can be considered both when the heart rate is high (tachycardia) and when it is low (bradycardia), if other secondary causes are excluded. For example, if the heart rate is high due to heart failure, anemia or increased activity of the thyroid gland, EP study is not recommended. Most often it is done just prior to electrical treatment of heart rhythm disorders. In cases of fast rhythms, the abnormal focus within the heart can be located by EP study and a small targeted radiofrequency (RF) current can be delivered to the site to destroy the trouble making focus. This process is known as RF ablation. If RF ablation is successful, the abnormal rhythm does not recur and the person can avoid lifelong medications which would otherwise be needed to suppress the disease.
How is an EP study done?
EP study is done in cardiac catheterization laboratory which has been modified by additional equipment for the purpose. Patient is kept fasting for a few hours prior to the procedure. In adult person, only local anaesthesia is needed for the procedure. In children who get frightened, general anaesthesia may be needed. Small electrode catheters are introduced into the heart through the blood vessels of the neck or groin. Skin puncture under local anaesthesia is used for the procedure. The tips of the electrode catheters are placed in various parts of the heart under X-ray fluoroscopic guidance. The electrical signals from each region is recorded in the EP recorder, which is an advanced type of ECG machine with monitor. An electrical signal generator is then used to pace different parts of the heart to check the way in which signal travels within the heart. Sometimes the abnormal heart rhythm is induced during the procedure. If that occurs, the origin and path it takes within the heart can be identified by signal mapping. This helps in guiding treatment with RF ablation as mentioned above.
Is RF ablation curative?
In certain types of heart rhythm disorders like supraventricular tachycardia (SVT) which originates in the upper chamber of the heart, success rate is around 95%. But for another one called atrial fibrillation success rate is lower around 60%. But recurrence can be often be treated by a repeat procedure. Success rates for abnormal rhythms originating from the lower chambers (ventricular tachycardia) depends on its cause. Those without structural cause or inherited electrical defect have good success rates.