Johns Hopkins University

David George Hunter

Henry R Halperin

Ronald David Berger

Harikrishna Tandri

Leslie Tung

Seth Weinberg

Ehud J Schmidt

Ronald D Watkins

David Lee Guyton

Robert L Fry

Julie Christine Sandruck

Saurabh Navinchandra Patel

A magnetic-resonance-imaging-compatible (MRI-compatible) cardiac defibrillator includes: a defibrillator generator; first and second electric wires, each being electrically connected to said defibrillator generator; first and second defibrillation pads, each being electrically connected to a respective one of said first and second electric wires; and a low pass filter electrically connected between said defibrillator generator and said first and second electric wires to prevent a noise in an MRI image caused by a radiofrequency interference from the defibrillator as well as protect a patient and the defibrillator from MRI radiofrequency imaging signals, wherein said low pass filter has a cutoff frequency set such that differential mode noise at an MRI Larmor frequency is in an attenuated band while a system-test signal by said defibrillator generator is in a pass band of said low pass filter.

MRI-compatible cardiac defribrillator

The present invention provides both methods and devices for termination of arrhythmias, such as ventricular or atrial tachyarrhythmias. The device and method involves application of alternating current (AC) for clinically significant durations at selected therapeutic frequencies through the cardiac tissue to a subject experiencing arrhythmia. Methods are also provided to minimize or eliminate pain during defibrillation.

Method and device for treating cardiac arrhythmias

MRI-compatible cardiac defibrillator

Apparatus and method are provided for assessing the direction of fixation of an eye by detecting polarization-related changes in light retroreflected from the fundus of the eye. Nerve fibers in the retina of the eye are birefringent and alter the polarization state of light traversing them as a function of their orientation. The nerve fibers are arrayed in a characteristic pattern in the retina, specifically radiating outward from the fovea and converging to the optic nerve head. By assessment of polarization-related changes in rctroreflected light from multiple retinal areas either sequentially or simultaneously, characteristic birefringence signatures of portions of the retina can be identified which are used to assess the direction of fixation of the eye. In addition, interference from the corneal birefringence is reduced by using incident light having a polarization state that is substantially independent of meridional direction. Circularly polarized light or non-polarized light is used for the assessment. Interference from the corneal birefringence is reduced still further by detecting polarization-related changes that are substantially independent of the meridional direction of the corneal birefringence. This is accomplished by detecting changes in ellipticity by measuring solely the Stokes parameter S.sub.3 or by measuring any two Stokes parameters. An alternative is measuring the overall intensity of the retroreflected light when the dichroism of the lutein pigment particles in the vicinity of the fovea is used for the assessment.

Eye fixation monitor and tracker

Growing community of inventors

Baltimore, MD, United States of America

David George Hunter