The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 20, 1981
Filed:
Aug. 15, 1979
George Benzing, III, Cincinnati, OH (US);
Rumult Iltis, Cincinnati, OH (US);
Children's Hospital Medical Center, Cincinnati, OH (US);
Abstract
A method and apparatus are disclosed for measuring the ohmic, that is, purely d-c, resistance at the area of contact between cardiac tissue and a pacemaker electrode surgically implanted in the heart of a patient requiring a pacemaker. The contact resistance is measured by apparatus connected across the electrical circuit formed by the electrode and heart. The apparatus includes circuitry for sampling and holding the instantaneous voltage across the electrical circuit formed by the electrode and heart at the onset of a pulse generated by the pacemaker pulse generator, at which time the effect of a parallel capacitance in the electrical circuit formed by the pulse generator, electrode wire, electrode, heart, and return path through the body to the pulse generator is such that the current initially produced is determined only by the voltage and equivalent output impedance of the pulse generator, the resistance of the electrode wire, and the resistance at the area of contact between cardiac tissue and the electrode. The apparatus further includes analog signal processing circuitry for deriving the contact resistance from the instantaneous voltage based on an equivalent circuit model for the electrical circuit formed by the pacemaker and the heart taking into account the effect of the parallel capacitance at the onset of a pulse. The apparatus also includes a device for displaying the measured contact resistance. The disclosed method and apparatus are also applicable for measuring the ohmic contact resistance of an electrode attached to other body tissue.