The purpose of this study is:

• To document the incidence of electromagnetic oversensing of ICDs during non-thoracic surgery.
• To identify any non-thoracic procedure with a higher incidence of generating electromagnetic oversensing.
• To document the ability of dual chamber ICDs to discriminate electromagnetic oversensing.

Electrocautery devices used during surgery generate a high electromagnetic field with a frequency that may result in ICD oversensing. Oversensing may in turn result in false detection of a ventricular arrhythmia and for the ICD to discharge. Because of this possibility, patients frequently have their ICDs inactivated prior to the procedure.

Although oversensing appears to be highly unlikely in clinical practice, vast resources are utilized in the process of deactivating and reactivating ICDs for surgeries. In addition, there are reports of deaths from failure to reactivate ICDs following elective surgery.

In this study we intend to document the incidence of oversensing, identify procedures with a higher likelihood of oversensing and evaluate the ability of dual chamber ICDs to discriminate electromagnetic oversensing.

Inclusion Criteria:

• Patients with Medtronic or Boston Scientific single and dual chamber ICDs

Exclusion Criteria:

• Non-thoracic ICD generator placement (abdominal)
• Pregnant

Patients undergoing elective, non-thoracic surgical procedures will be enrolled.