# US 2021/0330237 A1 · Apparatus and a method for qt correction > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0330237 A1 - Document ID: US20210330237A1 - Status: Published application - Kind: A1 - Application number: 17/370,660 - Filed: 2021-07-08 - Published: 2021-10-28 - Earliest claimed: 2019-03-22 - Assignees: Tampere University Foundation sr - Applicants: Tampere University Foundation sr - Inventors: Ilya POTAPOV; Esa RÄSÄNEN; Katriina AALTO-SETÄLÄ - Web page: https://patentgrep.com/patent/US20210330237A1 ## CPC - A61B 5/36: Detecting PQ interval, PR interval or QT interval - A61B 5/364: Detecting abnormal ECG interval, e.g. extrasystoles, ectopic heartbeats - A61B 5/02455: {provided with high/low alarm devices} - A61B 5/352: Detecting R peaks, e.g. for synchronising diagnostic apparatus; Estimating R-R interval - A61B 5/366: Detecting abnormal QRS complex, e.g. widening - A61B 5/7203: {for noise prevention, reduction or removal} - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) ## Abstract A method for QT correction is provided, the method comprising receiving an ECG signal; extracting a plurality of beat-to-beat (RR) intervals; extracting a plurality of QT intervals; computing a first probability distribution for a range of QT values based on the plurality of QT intervals; computing a second probability distribution for a range of QT values based on the plurality of QT intervals and the plurality of RR intervals; solving one or more points, wherein the first probability distribution and the second probability distribution intersect or wherein a difference between the first probability distribution and the second probability distribution is below a pre-defined difference threshold; designating one of one or more QT values corresponding to the one or more points as a corrected QT interval for a given QT interval of the plurality of QT intervals. ## Claims ### Claim 1 A method comprising receiving, by an apparatus, an electrocardiogram, ECG, signal; extracting, by the apparatus, a plurality of beat-to-beat (RR) intervals; extracting a plurality of QT intervals; computing, by the apparatus, a first probability distribution for a range of QT values based on the plurality of QT intervals; computing, by the apparatus, a second probability distribution for a range of QT values based on the plurality of QT intervals and the plurality of RR intervals; solving, by the apparatus, one or more points, wherein the first probability distribution and the second probability distribution intersect or wherein a difference between the first probability distribution and the second probability distribution is below a pre-defined difference threshold; designating, by the apparatus, one of one or more QT values corresponding to the one or more solved points as a corrected QT interval for a given QT interval of the plurality of QT intervals. ### Claim 2 (depends on 1) The method according to claim 1, wherein the first probability distribution defines a probability of detecting the given QT interval of the plurality of QT intervals provided the QT interval(s) prior to the given QT interval were detected. ### Claim 3 (depends on 1) The method according to claim 1, wherein the second probability distribution defines a probability of detecting the given QT interval of the plurality of QT intervals provided the QT interval(s) prior to the given QT interval and the RR interval(s) prior to the given QT interval or a given RR interval of the plurality of RR intervals were detected. ### Claim 4 (depends on 2) The method according to claim 2, wherein the QT intervals prior to the given QT interval comprise 5 to 10 QT intervals preceding the given QT interval. ### Claim 5 (depends on 3) The method according to claim 3, wherein the RR intervals prior to the given RR interval comprise 5 to 10 RR intervals preceding the given RR interval. ### Claim 6 (depends on 1) The method according to claim 1, further comprising designating the one or more QT values corresponding to the one or more solved points as one or more candidate QT intervals for the given QT interval; and selecting a candidate QT interval which is closest to a QT interval observed at a pre-defined heart rate to be designated as the corrected QT interval. ### Claim 7 (depends on 6) The method according to claim 6, further comprising in response to not observing the pre-defined heart rate, extrapolating QT and RR data derived from the ECG signal towards the pre-defined heart rate. ### Claim 8 (depends on 1) The method according to claim 1, further comprising designating the one or more QT values corresponding to the one or more solved points as one or more candidate QT intervals for the given QT interval; and selecting a candidate QT interval which has a maximum probability to be designated as the corrected QT interval. ### Claim 9 (depends on 1) The method according to claim 1, further comprising designating the one or more QT values corresponding to the one or more solved points as one or more candidate QT intervals for the given QT interval; and forming a relation based on at least a probability of a candidate QT interval, a distance between the QT candidate interval and a QT interval observed at a pre-defined heart rate, and a distance between the QT candidate interval and the given QT interval; selecting a candidate QT interval minimizing the relation to be designated as the corrected QT interval. ### Claim 10 (depends on 1) The method according to claim 1, further comprising one or more of: providing the corrected QT interval for display; providing results determined based on an electrocardiography recording for display; causing an alarm if the corrected QT interval is below a first pre-defined threshold or above a second pre-defined threshold. ### Claim 11 An apparatus comprising means for performing: receiving an ECG signal; extracting a plurality of beat-to-beat (RR) intervals; extracting a plurality of QT intervals; computing a first probability distribution for a range of QT values based on the plurality of QT intervals; computing a second probability distribution for a range of QT values based on the plurality of QT intervals and the plurality of RR intervals; solving one or more points, wherein the first probability distribution and the second probability distribution intersect or wherein a difference between the first probability distribution and the second probability distribution is below a pre-defined difference threshold; designating one of one or more QT values corresponding to the one or more solved points as a corrected QT interval for a given QT interval of the plurality of QT intervals. ### Claim 12 (depends on 11) The apparatus according to claim 11, wherein the first probability distribution defines a probability of detecting the given QT interval of the plurality of QT intervals provided the QT interval(s) prior to the given QT interval were detected. ### Claim 13 (depends on 11) The apparatus according to claim 11, wherein the means are further configured to perform: designating the one or more QT values corresponding to the one or more solved points as one or more candidate QT intervals for the given QT interval; and selecting a candidate QT interval which is closest to a QT interval observed at a pre-defined heart rate to be designated as the corrected QT interval. ### Claim 14 (depends on 11) The apparatus according to claim 11, wherein the means are further configured to perform: in response to not observing the pre-defined heart rate, extrapolating QT and RR data derived from the ECG signal towards the pre-defined heart rate. ### Claim 15 (depends on 11) The apparatus according to claim 11, wherein the means are further configured to perform: designating the one or more QT values corresponding to the one or more solved points as one or more candidate QT intervals for the given QT interval; and selecting a candidate QT interval which has a maximum probability to be designated as the corrected QT interval. ### Claim 16 (depends on 11) The apparatus according to claim 11, wherein the means are further configured to perform: designating the one or more QT values corresponding to the one or more solved points as one or more candidate QT intervals for the given QT interval; and forming a relation based on at least a probability of a candidate QT interval, a distance between the QT candidate interval and a QT interval observed at a pre-defined heart rate, and a distance between the QT candidate interval and the given QT interval; selecting a candidate QT interval minimizing the relation to be designated as the corrected QT interval. ### Claim 17 (depends on 11) The apparatus according to claim 11, wherein the means are further configured to perform: providing the corrected QT interval for display; providing results determined based on an electrocardiography recording for display; causing an alarm if the corrected QT interval is below a first pre-defined threshold or above a second pre-defined threshold. ### Claim 18 (depends on 11) The apparatus according to claim 11, wherein the means comprises at least one processor; at least one memory including computer program code; the at least one memory and the computer program code configured to, with the at least one processor, cause the performance of the apparatus. ### Claim 19 (depends on 11) The apparatus according to claim 11, wherein the apparatus is a wearable monitoring device or an electrocardiogram monitoring device. ### Claim 20 A non-transitory computer readable medium comprising computer program code configured to, when executed on at least one processor of an apparatus, cause the apparatus to perform: receiving an ECG signal; extracting a plurality of beat-to-beat (RR) intervals; extracting a plurality of QT intervals; computing a first probability distribution for a range of QT values based on the plurality of QT intervals; computing a second probability distribution for a range of QT values based on the plurality of QT intervals and the plurality of RR intervals; solving one or more points, wherein the first probability distribution and the second probability distribution intersect or wherein a difference between the first probability distribution and the second probability distribution is below a pre-defined difference threshold; designating one of one or more QT values corresponding to the one or more solved points as a corrected QT interval for a given QT interval of the plurality of QT intervals.