Generally, active implantable medical devices (AIMDs) are powered devices (other than from the human body or gravity) that are inserted into a patient’s body partially or fully through a natural orifice or by surgical means, and are intended to remain in the patient’s body. For example, coronary pacemakers, cochlear hearing implants, infusion pumps or neurostimulators. The UK and EU legislative definitions differ and are as follows:
The UK Medical Devices Regulations 2002 (MDR 2002), SI 2002/618, which implement Directive 90/385/EEC, the Active Implantable Medical Devices Directive in the UK, define AIMD as:
‘…a medical device which—
• relies for its functioning on a source of electrical energy or a source of power other than that generated directly by the human body or by gravity; and
• is intended to be totally or partially introduced into the human body (whether surgically or medically, including being introduced into a natural orifice) and which is intended to remain in the human body after completion of the surgical or medical procedure during which it is introduced,
even if it is intended to administer a medicinal product or incorporates as an integral part a substance which, if used separately, would be a medicinal product.’
Under Regulation (EU) 2017/745, the Medical Devices Regulation (EU MDR), an active device and an implantable device are separately defined:
‘…active device means any device, the operation of which depends on a source of energy other than that generated by the human body for that purpose, or by gravity, and which acts by changing the density of or converting that energy. Devices intended to transmit energy, substances or other elements between an active device and the patient, without any significant change, shall not be deemed to be active devices. Software shall also be deemed to be an active device.’
‘…implantable device means any device, including those that are partially or wholly absorbed, which is intended:
•
to be totally introduced into the human body, or
•
to replace an epithelial surface or the surface of the eye
by clinical intervention and which is intended to remain in place after the procedure.
Any device intended to be partially introduced into the human body by clinical intervention and intended to remain in place after the procedure for at least 30 days shall also be deemed to be an implantable device.’
Specific requirements for AIMDs are set out in Annex I of the EU MDR at Chapter 2, section 19.