The disclosure provides methods and apparatus for simultaneously providing protection to an implantable
medical device, such as an extra-cardiac implantable defibrillator (EID), while allowing efficacious therapy delivery via an external defibrillator (e.g., an
automated external defibrillator, or AED). Due to the orientation of the electrodes upon application of therapy via, for example, via an AED the structure of the EID essentially blocks therapy delivery. In addition, but for the teaching of this disclosure sensitive circuitry of an EID can be damaged during application of external
high voltage therapy thus rendering the EID inoperable. EIDs are disclosed that are entirely implantable subcutaneously with minimal surgical intrusion into the body of the patient and provide distributed
cardioversion-
defibrillation sense and stimulation electrodes for delivery of
cardioversion-
defibrillation shock and pacing therapies across the heart when necessary. Configurations include one hermetically sealed housing with one or, optionally, two subcutaneous sensing and
cardioversion-
defibrillation therapy delivery leads or alternatively, two hermetically sealed housings interconnected by a power /
signal cable. The housings are generally dynamically configurable to adjust to varying rib structure and associated articulation of the
thoracic cavity and muscles. Further the housings may optionally be flexibly adjusted for ease of
implant and
patient comfort. One aspect includes partially insulating a surface of an EID that faces away from a heart while maintaining a major conductive surface facing the heart.