Holter monitor is essentially EKG of the heart for 24 hours. Patients get the monitor with leads (stickers). Staff will give instructions on how to apply the leads along with precautions. Patients are expected to do their regular activities during the 24 hour period. After the monitor is returned, the data is then decoded and analyzed by the computer software and the physician. The holter monitor is the size of an average cellphone. Common reasons to get a Holter monitor are palpitations, dizziness or arrythmia that physician is monitoring.