Abstract: A method of determining respiratory phase of a living body from a sequence of digitized fluoroscopic images of a living-body region exhibiting respiratory displacement, the method employing programmable computing apparatus and comprising the steps of: (a) in each living-body-region image in the sequence, defining one or more zones with each image having identical image-to-image zone locations, sizes, and shapes; (b) for each image, computing an average pixel intensity for each zone to form a sequence thereof for each zone; (c) for each zone, modifying the average pixel intensities by (i) computing the mean value of the sequence of average pixel intensities for such zone, and (ii) subtracting the mean from each average pixel intensity in the zone; (d) for each zone sequence, computing a figure-of-merit; (e) selecting the zone having the highest figure-of-merit; and (f) using the sequence of pixel intensities of the selected zone to determine respiratory phase.

Abstract: A method for automatically determining the 3D position and orientation of a radio-opaque medical object in a living body using single-plane fluoroscopy comprising: (a) capturing a stream of digitized 2D images from a single-plane fluoroscope; (b) detecting an image of the medical object in a subset of the digital 2D images; (c) applying to the digital 2D images calculations which preserve original pixel intensity values and permit statistical calculations thereon, using (i) multiple sequential determinations of a midline of the medical object image, (ii) a plurality of unfiltered raw-data cross-sectional intensity profiles perpendicular to each sequentially-determined midline, (iii) removal of outlier profiles from each plurality of profiles, and (iv) statistically combining each plurality of profiles to estimate image dimensions; (d) applying conical projection and radial elongation corrections to the image measurements; and (e) calculating the 3D position and orientation of the medical object from the corre

Abstract: A method of determining respiratory phase of a living body from a sequence of digitized fluoroscopic images of a living-body region exhibiting respiratory displacement, the method employing programmable computing apparatus and comprising the steps of: (a) in each living-body-region image in the sequence, defining one or more zones with each image having identical image-to-image zone locations, sizes, and shapes; (b) for each image, computing an average pixel intensity for each zone to form a sequence thereof for each zone; (c) for each zone, modifying the average pixel intensities by (i) computing the mean value of the sequence of average pixel intensities for such zone, and (ii) subtracting the mean from each average pixel intensity in the zone; (d) for each zone sequence, computing a figure-of-merit; (e) selecting the zone having the highest figure-of-merit; and (f) using the sequence of pixel intensities of the selected zone to determine respiratory phase.

Abstract: A method of determining respiratory phase of a living body from a sequence of digitized fluoroscopic images of a living-body region exhibiting respiratory displacement.

Abstract: A method of determining respiratory phase of a living body from a sequence of digitized fluoroscopic images of a living-body region exhibiting respiratory displacement.

Abstract: An automatic method of determining local activation time (LAT) from at least three multi-channel cardiac electrogram signals including a mapping channel and a plurality of reference channels. The method comprises (a) storing the cardiac channel signals, (b) using the mapping-channel signal and a first reference-channel signal to compute LAT values at a plurality of mapping-channel locations, (c) monitoring the timing stability of the first reference-channel signal, and (d) if the timing stability of the monitored signal falls below a stability standard, using the signal of a second reference channel to determine LAT values. Substantial loss of LAT values is avoided in spite of loss of timing stability.

Abstract: A method for generating a 3D map of a cardiac parameter in a region of a living heart, the method using single-plane fluoroscopic images and comprising: (a) placing a plurality of catheters each having one or more radio-opaque sensors into the region such that the locations of the sensors geometrically span the region; (b) capturing a first-view digitized 2D image of the region from a first fluoroscope positioned at a first angle; (c) identifying each of the plurality of sensors in the first-view image; (d) capturing a second-view digitized 2D image of the region from a second fluoroscope positioned at a second angle which is different from the first angle; (e) identifying each of the plurality of sensors in the second-view image; (f) associating each of the plurality of identified sensors in the second-view image with its corresponding identified sensor in the first-view image; (g) sensing and storing values of the cardiac parameter with each of the plurality of sensors; (h) determining the 3D location of ea

Abstract: A method for generating a 3D map of a cardiac parameter in a region of a living heart, the method using single-plane fluoroscopic images and comprising: (a) placing a plurality of catheters each having one or more radio-opaque sensors into the region such that the locations of the sensors geometrically span the region; (b) capturing a first-view digitized 2D image of the region from a first fluoroscope positioned at a first angle; (c) identifying each of the plurality of sensors in the first-view image; (d) capturing a second-view digitized 2D image of the region from a second fluoroscope positioned at a second angle which is different from the first angle; (e) identifying each of the plurality of sensors in the second-view image; (f) associating each of the plurality of identified sensors in the second-view image with its corresponding identified sensor in the first-view image; (g) sensing and storing values of the cardiac parameter with each of the plurality of sensors; (h) determining the 3D location of ea

Abstract: A method for automatically determining the 3D position and orientation of a radio-opaque medical object in a living body using single-plane fluoroscopy comprising: (a) capturing a stream of digitized 2D images from a single-plane fluoroscope; (b) detecting an image of the medical object in a subset of the digital 2D images; (c) applying to the digital 2D images calculations which preserve original pixel intensity values and permit statistical calculations thereon, using (i) multiple sequential determinations of a midline of the medical object image, (ii) a plurality of unfiltered raw-data cross-sectional intensity profiles perpendicular to each sequentially-determined midline, (iii) removal of outlier profiles from each plurality of profiles, and (iv) statistically combining each plurality of profiles to estimate image dimensions, thereby to measure the medical-object image from a final estimation of image dimensions; (d) applying conical projection and radial elongation corrections to the image measurements;

Abstract: A method for detecting a stimulus pulse by using two or more electrical signals derived from a living body, the method comprising the following steps: (a) for each electrical signal, digitizing the signal with an analog-to-digital converter to produce a sampled signal Sk; (b) for each signal Sk at a sample time ti, computing a primary difference ?kp(ti)=abs[Sk(ti)?Sk(ti?p)]; (c) determining the minimum value of all of the computed differences, such minimum being a detector output D(ti); (d) comparing the detector output D(ti) with a detection threshold; and (e) indicating that a stimulus pulse has been detected when the detector output D(ti) is above the detection threshold.

Abstract: A method for automatically determining the 3D position and orientation of a radio-opaque medical object in a living body using single-plane fluoroscopy comprising capturing a stream of digitized 2D images from a single-plane fluoroscope (10), detecting the image of the medical object in a subset of the digital 2D images, applying pixel-level geometric calculations to measure the medical-object image, applying conical projection and radial elongation corrections (31) to the image measurements, and calculating the 3D position and orientation of the medical object from the corrected 2D image measurements.

Abstract: An automatic method of determining local activation time (LAT) from at least three multi-channel cardiac electrogram signals including a mapping channel and a plurality of reference channels. The method comprises (a) storing the cardiac channel signals, (b) using the mapping-channel signal and a first reference-channel signal to compute LAT values at a plurality of mapping-channel locations, (c) monitoring the timing stability of the first reference-channel signal, and (d) if the timing stability of the monitored signal falls below a stability standard, using the signal of a second reference channel to determine LAT values. Substantial loss of LAT values is avoided in spite of loss of timing stability.

Abstract: A method for detecting a stimulus pulse by using two or more electrical signals derived from a living body, the method comprising the following steps: (a) for each electrical signal, digitizing the signal with an analog-to-digital converter to produce a sampled signal Sk; (b) for each signal Sk at a sample time ti, computing a primary difference ?kp(ti)=abs[Sk(ti)?Sk(ti?p)]; (c) determining the minimum value of all of the computed differences, such minimum being a detector output D(ti); (d) comparing the detector output D(ti) with a detection threshold; and (e) indicating that a stimulus pulse has been detected when the detector output D(ti) is above the detection threshold.

Abstract: An automatic method of determining local activation time (LAT) from at least four multi-channel cardiac electrogram signals including a ventricular channel, a mapping channel and a plurality of reference channels. The method comprises (a) storing the cardiac channel signals, (b) using the ventricular and mapping channel signals and a first reference channel signal to compute LAT values at a plurality of mapping-channel locations, (c) monitoring the timing stability of the first reference channel signal, and (d) if the timing stability of the monitored signal falls below a stability standard, using the signal of a second reference channel to determine LAT values. Substantial loss of LAT values is avoided in spite of loss of timing stability.

Abstract: An automatic method of determining local activation time (LAT) from at least four multi-channel cardiac electrogram signals including a ventricular channel, a mapping channel and a plurality of reference channels. The method comprises (a) storing the cardiac channel signals, (b) using the ventricular and mapping channel signals and a first reference channel signal to compute LAT values at a plurality of mapping-channel locations, (c) monitoring the timing stability of the first reference channel signal, and (d) if the timing stability of the monitored signal falls below a stability standard, using the signal of a second reference channel to determine LAT values. Substantial loss of LAT values is avoided in spite of loss of timing stability.

Abstract: An automatic method for categorizing heartbeats using two or more selected ECG signals, the method comprising, when a heartbeat has been detected, the steps of: (a) determining a signal velocity for each selected signal at a categorization fiducial time tC within the detected heartbeat; (b) forming a vector F(tC) having as its components the velocities of each of the selected signals at time tC; (c) determining the angle between the vector F(tC) and a previously-stored template vector; (d) comparing the angle with a threshold angle; and (e) if the angle is less than the threshold angle, categorizing the heartbeat as similar to a heartbeat which corresponds to the template vector.

Abstract: An automatic method for detecting heartbeats of a patient from two or more selected ECG signals, the method comprising: (a) determining a velocity for each of the selected signals; (b) summing together absolute values of each of the velocities; (c) comparing the sum with a threshold T having a value about one-half of an expected maximum value of the sum; and (d) if the sum is greater than the threshold T and if elapsed time since an immediately-previous heartbeat detection is greater than a preset refractory period tR, a heartbeat has been detected at a time tD of the velocity determinations. The method also further includes steps by which the detected heartbeats are categorized based on the velocities at the time of detection.

Abstract: An automatic method for categorizing heartbeats using two or more selected ECG signals, the method comprising, when a heartbeat has been detected, the steps of: (a) determining a signal velocity for each selected signal at a categorization fiducial time tC within the detected heartbeat; (b) forming a vector F(tC) having as its components the velocities of each of the selected signals at time tC; (c) determining the angle between the vector F(tC) and a previously-stored template vector; (d) comparing the angle with a threshold angle; and (e) if the angle is less than the threshold angle, categorizing the heartbeat as similar to a heartbeat which corresponds to the template vector.

Abstract: An automatic method for detecting heartbeats of a patient from two or more selected ECG signals, the method comprising: (a) determining a velocity for each of the selected signals; (b) summing together absolute values of each of the velocities; (c) comparing the sum with a threshold T having a value about one-half of an expected maximum value of the sum; and (d) if the sum is greater than the threshold T and if elapsed time since an immediately-previous heartbeat detection is greater than a preset refractory period tR, a heartbeat has been detected at a time tD of the velocity determinations. The method also further includes steps by which the detected heartbeats are categorized based on the velocities at the time of detection.

Abstract: A method for detecting an R-wave from an ECG signal derived from a living body, the ECG signal including a plurality of ECG channel signals, the method comprising the steps of providing a plurality of channel R-wave detectors each processing a distinct signal of the plurality of channel ECG signals to generate a distinct channel trigger signal of a plurality of channel trigger signals, and inputting each channel trigger signal into a composite R-wave detector to generate a composite R-wave trigger, whereby the composite R-wave detector more accurately detects R-waves than each of the plurality of channel R-wave detectors.