The sensation will differ for each individual patient. A shock from an ICD can feel like a sharp or quick thump to the chest. The muscles in your chest and upper arm may tighten so strongly that you jump up in surprise. Try not to worry if this happens, remember that a defibrillating shock from an ICD can be lifesaving. If there is any pain caused by a shock, it often passes quickly. Anyone touching you at the time you get the shock may feel a muscle spasm or a tingle. It will not hurt the person touching you. Any questions on what to expect in the event of a shock should be directed to your doctor.