Implantable automatic difibrillator with low threshold
First Claim
1. An automatic defibrillator adapted to be implanted in the body of a patient, comprising stimulus generator means for sensing fibrillation of the patient'"'"'s heart and responsive thereto for delivering defibrillation energy to the patient'"'"'s heart via a defibrillation electrode adapted to be positioned in the heart, an electrically conductive case housing said stimulus generator means, and a conforming biocompatible electrically insulating layer coating a central region at a side of the case which is to face inwardly of the patient'"'"'s body when the stimulus generator means is implanted, to leave at least a portion of the edge bounding said side uninsulated and thereby produce a predetermined electric field concentration between said defibrillation electrode and the uninsulated portion of the boundary edge of said side when the case is used as an electrode for defibrillation.
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Accused Products
Abstract
An automatic defibrillator is arranged and adapted to be implanted in a cardiac patient. The defibrillator includes a stimulus generator for sensing fibrillation of the patient'"'"'s heart and for responding by delivering defibrillation energy to the patient'"'"'s heart via a defibrillation electrode positioned in the right ventricle of the heart. An electrically conductive case houses the stimulus generator, and a conforming biocompatible electrically non-conductive layer is coated over only a predetermined portion less than all of the case to produce a predetermined shape of electric field between the intracardiac defibrillation electrode and the case when the case is used as an electrode for defibrillation. The predetermined portion of the case coated with the non-conductive layer includes a side of the case to be implanted in a direction facing the heart of the patient, with the non-conductive layer being confined solely to the central portion of that side.
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Citations
21 Claims
- 1. An automatic defibrillator adapted to be implanted in the body of a patient, comprising stimulus generator means for sensing fibrillation of the patient'"'"'s heart and responsive thereto for delivering defibrillation energy to the patient'"'"'s heart via a defibrillation electrode adapted to be positioned in the heart, an electrically conductive case housing said stimulus generator means, and a conforming biocompatible electrically insulating layer coating a central region at a side of the case which is to face inwardly of the patient'"'"'s body when the stimulus generator means is implanted, to leave at least a portion of the edge bounding said side uninsulated and thereby produce a predetermined electric field concentration between said defibrillation electrode and the uninsulated portion of the boundary edge of said side when the case is used as an electrode for defibrillation.
- 8. A method of defibrillating a patient'"'"'s heart with an automatic implanted defibrillator, comprising the steps of sensing fibrillation of the patient'"'"'s heart and responding thereto by delivering defibrillation energy to the patient'"'"'s heart from a stimulus generator of the defibrillator via a defibrillation electrode in the heart, using the electrically conductive case that houses the stimulus generator as a second electrode for defibrillation, and concentrating an electric field attributable to the delivery of defibrillation energy between the defibrillation electrode and the second electrode over a predetermined portion constituting less than all of a side of the case facing inwardly of the patient'"'"'s body.
- 17. An automatic, body-implantable defibrillator device comprising an electrical waveform generator for detecting fibrillation of atrial or ventricular chambers of a patient'"'"'s heart and for response thereto by generating defibrillation energy to be delivered to the fibrillating chambers, and an electrically conducting case with a pair of side walls separated by an end wall to form a sealed enclosure for said generator, said case having an electrically insulating external surface pattern to render at least a substantial part of an exposed surface of each of the side walls insulated and an exposed surface of the end wall uninsulated in a surface ring configuration.
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19. A method of establishing an electric field pattern conducive to defibrillating the atrial or ventricular chambers of a patient'"'"'s heart with relatively low energy levels, said method comprising the steps of positioning a pair of defibrillation electrodes with one of said pair on a transvenous lead and located in a chamber to be defibrillated at the right side of the heart, and with the other of said electrodes being an electrically conducting housing of a defibrillation waveform generator implanted in the left pectoral region of the patient with a pattern of insulating material on the surface of said housing exposed to said transvenous lead electrode so that when a defibrillation waveform is delivered across said pair of electrodes the electric field produced therebetween is concentrated in a ring-like pattern at the periphery of said housing relative to said transvenous lead electrode.
- 20. A method of preparing the electrically conducting housing of an implantable defibrillation waveform generator for use as one defibrillation electrode for interaction with another defibrillation electrode located on a transvenous lead to be introduced into a chamber in the right side of a heart, said method comprising applying a layer of electrically insulating biocompatible material onto an external surface of said housing and conforming thereto in a pattern wherein at least a substantial part of an exposed surface of each of a pair of side walls of said housing is insulated and an exposed surface of an end wall of said housing separating said side walls to form a sealed enclosure is left uninsulated as a conducting surface ring configuration.
Specification