Patent ID: 8768460

Claim:
A system comprising: an implantable energy delivery circuit configured to deliver a nondefibrillating and nonfibrillation-inducing energy to a first thoracic region; a first implantable electric field detector configured to detect, in response to the nondefibrillating and nonfibrillation-inducing energy, a first electric field at a second thoracic region, wherein the second thoracic location includes a location in, on, or near at least one of a left apical region of the heart or a left ventricular free lateral wall of the heart; a second implantable electric field detector configured to detect, in response to the same nondefibrillating and nonfibrillation-inducing energy, a second electric field between a third thoracic region and a fourth thoracic region, wherein the third thoracic region includes a location at or near at least a portion of the first thoracic region, and wherein the fourth thoracic location includes a location at or near at least a portion of the second thoracic region; and an implantable or external controller configured to calculate an estimated defibrillation threshold using the nondefibrillating and nonfibrillation-inducing energy, the detected first electric field, and the detected second electric field.