**Abstract**

Implantable devices, including Implantable Cardiac Defibrillators (ICD) and Pacemakers (PM), are being seen with increasing frequency in patients wanting to conduct recreational diving or referred for Hyperbaric Oxygen Therapy (HBOT). Under hyperbaric conditions, these devices are at risk of malfunction, mostly by changes of ambient pressure. In some cases, manufacturers publish information on how their devices operate under increased pressure. Unfortunately, this is not always the case, and for other devices, someone must perform an individual risk-benefit analysis specific for single patient and his/her implanted device. In case of medical treatment, such analysis must take into account the patient's clinical condition, the indication for HBOT, and the capability of the HBOT facility for monitoring and intervention in the chamber.

**Keywords:** diving, hyperbaric medicine, oxygen, defibrillator
