Methods of characterizing ventricular operations and applications thereof

A method of characterising ventricular operation of a patient's heart, comprising sensing a plurality of electrical signals from different spatial positions with respect to the heart during depolarisation and repolarisation of the heart, the plurality of electrical signals being sensed by an implantable medical device and being associated with the propagation of depolarisation and repolarisation waves originating from a patient's heart, processing the electrical signals to yield a plurality of vectors which describe the propagation direction of a wavefront for a depolarisation wave and a plurality of vectors which describe the propagation direction of a wavefront for a repolarisation wave, wherein ventricular operation is characterised in terms of the cosine of the angle between the plurality of vectors for the depolarisation and repolarisation waves, wherein at least one of the plurality of vectors describes the propagation of the wavefront as a function of time and the mean of the cosine of the angle between pairs of vectors is determined.

An implantable medical device comprising a plurality of medical electrical leads, the leads having electrodes for sensing electrical signals from different spatial positions in, on or near a patient's heart, wherein the device processes the electrical signals to yield directions of propagation for depolarisation and repolarisation waves of a patients heart, calculates the angle of deviation between the depolarisation and repolarisation waves, and generates an output signal corresponding to the angle of deviation, wherein the output signal varies in accordance with the cosine of the angle of deviation.

A method of characterising ventricular operation, comprising sensing a plurality of electrical signals associated with the propagation of a repolarisation wave originating in the patient's heart, the plurality of electrical signals being sensed from different spatial positions on, in or near the patient's heart, processing the plurality of electrical signals to yield a plurality of vectors that are representative of the wavefront of the repolarisation wave, and determining a measure of the spatial variation of the repolarisation wavefront, wherein the spatial variation is calculated by determining vector contributions for the repolarisation wavefront in each of a set of predetermined directions and measuring the angle between pairs of vector contributions.

A method of characterising ventricular operation of a patient's heart, comprising sensing a plurality of electrical signals to monitor repolarisation of the heart from different spatial positions with respect to the patients heart, processing the plurality of signals to yield a vector describing the propagation of a repolarisation wave through the heart, projecting the vector onto a set of axes to determine vector contributions of the signal vector in the directions of the axes, and measuring the angle between pairs of vector contributions, wherein the vector corresponds to a direction of maximum energy of the repolarisation wave.

A method of characterising ventricular operation of a patient's heart comprising sensing a plurality of electrical signals to monitor propagation of repolarisation through the heart from different spatial positions with respect to the patient's heart, processing the plurality of electrical signals to yield a vector describing the propagation of a repolarisation wave with respect to time and with respect to a first set of axes defining an optimum domain space, mapping the path of a tip of the vector in the optimum domain space to generate a T-wave loop and calculating a parameter describing the morphology variation of that loop, wherein the parameter is determined by projecting the T-wave loop on to reconstruction vectors corresponding to electrode positions to generate vector contributions in those electrode directions, and determining the angle between all pairs of vector contributions.

A method of characterising ventricular operation of a patient's heart comprising sensing a plurality of electrical signals associated with the propagation of a repolarisation wave originating in the patient's heart from different spatial positions with respect to the patient's heart, processing the plurality of electrical signals to yield a vector which is representative of the wavefront of the repolarisation wave with respect to a first set of axes, transforming the vector to a second set of axes defining an optimised orthogonal domain having a first axis aligned with a direction of maximum energy, the domain comprising three dimensions representing the dipolar components of the repolarisation wavefront vector and at least one further dimension representing the non-dipolar components of the repolarisation wavefront vector and determining the energy of the non-dipolar components, wherein said optimised orthogonal domain has eight dimensions and the transformed repolarisation wavefront vector S has eight components s1 to s8 corresponding one to each dimension, wherein the vector components are ranked in order of most significance with respect to energy and the non-dipolar components are represented by the fourth to eighth components s4 to s8.

A method of detecting whether a patient is healthy or sick, wherein more than one parameter characterising ventricular operation as claimed in any of claim 1, 3, 4, 5, 6, 14, 15, 16, 17, 19, 20, 21, 33 or 22 is calculated.

A method of detecting abnormalities of ventricular repolarisation in a patient using a method of characterising ventricular operation as claimed in any of claim 1, 3, 4, 5, 6, 14, 15, 16, 17, 19, 20, 21, 33 or 22, wherein preferably said method is a method of detecting the onset of ischemia.

A method of determining whether a patient is suffering from heart failure, and preferably a method of determining whether the patient is suffering from one of hypertropic cardiomyopathy, idiopathic dilated cardiomyopathy and acute myocardial infarction, comprising measuring a parameter characterising ventricular operation as claimed in any of claim 1, 3, 4, 5, 6, 14, 15, 16, 17, 19, 20, 21, 33 or 22, wherein preferably the method is accomplished by employing an implantable medical device which is capable of sensing depolarisation and repolarisation waves, and processing same.

A method of categorising subjects using a method of characterising ventricular operation as claimed in any of claim 1, 3, 4, 5, 6, 14, 15, 16, 17, 19, 20, 21, 33 or 22.

A method of monitoring the autonomic system of a subject, wherein a method of characterising ventricular operation as claimed in any of claim 1, 3, 4, 5, 6, 14, 15, 16, 17, 19, 20, 21, 33 or 22, is used to measure changes in the autonomic system of the subject, wherein the method is accomplished by employing an implantable medical device which is capable of sensing depolarisation and repolarisation waves and processing same.

A method of determining depolarisation start and end points for measuring characteristics of a signals representing changes in energy during depolarisation of a patient's heart, comprising finding a first peak in the energy of the signal corresponding to depolarisation of the patient's heart, determining a point in time, tRP, corresponding to the peak energy and determining the maximum energy ERmax of the signal at that point, determining a point in time t′RS before tRP and a point in time t′RE after tRP where the energy of the signal drops to a predetermined percentage of the maximum energy, determining the depolarisation start point by subtracting a first predetermined time interval from time t′RS and determining the depolarisation end point by adding a second predetermined time interval to time t′RE.