Before the catheter ablation is scheduled, electrophysiology studies will be performed to locate exactly where the abnormal rhythms are coming from. During an electrophysiology study (EP study), a catheter is placed into a blood vessel and fed all the way up to the heart. 

Once in place, the catheter is able to detect and map electrical currents in the heart. In this way, physicians are able to precisely pinpoint where abnormal impulses are originating. Once the physician has located the source of the arrhythmia(s), the catheter ablation can be scheduled. Additional tests that may be performed before ablation include an electrocardiogram, echocardiogram and maybe others, depending on any underlying conditions.

Patients may be instructed not to eat or drink anything for up to 8 hours before the ablation procedure. Any prescription drugs that manipulate the heart's electrical system may also be discontinued, including beta blockers, calcium channel blockers, digoxin and certain antiarrythmic drugs.  On the day of the procedure, they will be admitted to the hospital. A nurse or physician will explain what is going to happen, and patients are encouraged to ask any questions that they may have.