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: 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: 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.

Abstract: An automatic method of determining local activation time (LAT) in multi-channel cardiac electrogram signals including a ventricular channel, a reference channel and a mapping channel wherein selection of at least one of a reference-channel activation and a mapping-channel activation is based on one or more activation times in the ventricular channel.

Abstract: An automatic method of determining local activation time (LAT) in multi-channel cardiac electrogram signals including a plurality of cardiac channels, the method comprising: (a) storing the cardiac channel signals; (b) using a ventricular, a reference and a mapping channel to compute first LAT values at a plurality of mapping-channel locations; (c) monitoring the quality of at least one of the ventricular, reference and mapping channels; (d) if the quality of a monitored cardiac channel falls below a standard, replacing the sub-standard channel with another channel of the plurality of channels having an above-standard quality; and (e) computing second LAT values based on the replacement cardiac channel.

Abstract: An automatic method of determining local activation time (LAT) in multi-channel cardiac electrogram signals including a plurality of cardiac channels, the method comprising: (a) storing the cardiac channel signals; (b) using a ventricular, a reference and a mapping channel to compute first LAT values at a plurality of mapping-channel locations; (c) monitoring the quality of at least one of the ventricular, reference and mapping channels; (d) if the quality of a monitored cardiac channel falls below a standard, replacing the sub-standard channel with another channel of the plurality of channels having an above-standard quality; and (e) computing second LAT values based on the replacement cardiac channel.

Abstract: A method for detecting an R-wave from an ECG signal (x(t)) derived from a living body, the method comprising the steps of (a) acquiring the ECG signal from the living body, (b) digitizing the ECG signal into a digital ECG signal (x(ti)), (c) filtering the digital ECG signal with a bandpass filter (53) and applying an absolute value filter (55) thereto to create a filtered ECG signal (g(ti)), (d) for each sequential value of the filtered ECG signal, comparing (57) the filtered ECG signal to an ECG tracking threshold (TT), (e) if the filtered ECG signal is no greater than TT, incrementing a counter (59), but if greater than TT, setting the counter to zero; and (f) comparing (63) the counter to a predetermined refractory count RC and, if the count is equal to RC, outputting an R-wave trigger indicating that an R-wave has been detected.

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.

Abstract: An automatic method of determining local activation time (LAT) in multi-channel cardiac electrogram signals including a plurality of cardiac channels, the method comprising: (a) storing the cardiac channel signals; (b) selecting a mapping channel, a ventricular channel, and a reference channel from among the plurality of cardiac channels; (c) using the selected channels to compute first LAT values at a plurality of mapping-channel locations; (d) monitoring the quality of at least one selected channel; (e) if the quality of a monitored cardiac channel falls below a standard, replacing the sub-standard channel with another channel of the plurality of channels having an above-standard quality; and (f) computing second LAT values based on the replacement cardiac channel.

Abstract: An automatic method of measuring parameters of multi-channel cardiac electrogram signals including at least one ventricular channel and at least two other cardiac channels, the method comprising: (a) digitizing and filtering a ventricular-channel signal and a first other cardiac signal over a first preset time window to generate corresponding absolute-value velocity signals; (b) estimating a pulse interval in the ventricular absolute-value velocity signal; (c) autocorrelating the first other cardiac absolute-value velocity signal; (d) selecting a peak value of the autocorrelation based on ventricular pulse-interval estimates; and (e) setting the cycle length of the first other cardiac signal to the lag value of the selected peak in the autocorrelation. Local activation times are measured, and several multiple-channel configurations decrease measurement time, decrease the impact of signal degradation, and increase the amount of data generated during a procedure.

Abstract: An automatic method of determining local activation time (LAT) in multi-channel cardiac electrogram signals including at least two cardiac channels, one of the cardiac channels being a mapping channel and another cardiac channel being a reference channel, the method comprising: (a) estimating a cycle length CL in the reference channel; (b) determining a mapping-channel fiducial time tM in the mapping channel signal; (c) determining a plurality of reference-channel fiducial times tR; (d) computing adjusted reference-channel fiducial times tRA by adding or subtracting multiples of cycle length CL to each time tR such that each time tRA is within a time window of length CL surrounding mapping-channel fiducial time tM; (e) computing a single final reference-channel fiducial time tRF from the plurality of adjusted reference-channel fiducial times tRA; and (f) computing the LAT as tM minus tRF.

Abstract: A method for 3D reconstruction of the positions of a catheter as it is moved within a human body, comprising: (a) ascertaining the 3D position of a point on a catheter for insertion into the body; (b) acquiring fixed-angle, single-plane fluoroscopic image data of the body and catheter; (c) transferring the image data and catheter-point position to a computer; (d) determining 2D image coordinates of the point on the catheter; (e) changing the insertion length of catheter by a measured amount; (f) acquiring additional single-plane fluoroscopic image data of the body and catheter from the same angle, transferring the length change and image data to the computer, and determining image coordinates of the point on the catheter; (g) computing the 3D position of the catheter point; and (h) repeating steps e-g. A 3D model is constructed by assembling the plural 3D positions of the catheter point.

Abstract: A method for detecting an R-wave from an ECG signal (x(t)) derived from a living body, the method comprising the steps of (a) acquiring the ECG signal from the living body, (b) digitizing the ECG signal into a digital ECG signal (x(ti)), (c) filtering the digital ECG signal with a bandpass filter (53) and applying an absolute value filter (55) thereto to create a filtered ECG signal (g(ti)), (d) for each sequential value of the filtered ECG signal, comparing (57) the filtered ECG signal to an ECG tracking threshold (TT), (e) if the filtered ECG signal is no greater than TT, incrementing a counter (59), but if greater than TT, setting the counter to zero; and (f) comparing (63) the counter to a predetermined refractory count RC and, if the count is equal to RC, outputting an R-wave trigger indicating that an R-wave has been detected.

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.