# US 2017/0281097 A1 · Systems and methods for detecting worsening heart failure

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- Number: US 2017/0281097 A1
- Document ID: US20170281097A1
- Status: Published application
- Kind: A1
- Application number: 15/473,783
- Filed: 2017-03-30
- Published: 2017-10-05
- Earliest claimed: 2016-04-01
- Assignees: Cardiac Pacemakers, Inc.
- Applicants: Cardiac Pacemakers, Inc.
- Inventors: Pramodsingh Hirasingh Thakur; Yi Zhang; Qi An; Viktoria A. Averina
- Web page: https://patentgrep.com/patent/US20170281097A1

## CPC

- A61B 5/7275: {Determining trends in physiological measurement data; Predicting development of a medical condition based on physiological measurements, e.g. determining a risk factor}
- A61B 5/0205: Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
- A61B 5/091: Measuring volume of inspired or expired gases, e.g. to determine lung capacity
- A61B 5/4836: {Diagnosis combined with treatment in closed-loop systems or methods (A61B5/0036 takes precedence)}
- A61B 5/686: {Permanently implanted devices, e.g. pacemakers, other stimulators, biochips (A61B5/6861 takes precedence)}
- A61B 5/7264: {Classification of physiological signals or data, e.g. using neural networks, statistical classifiers, expert systems or fuzzy systems}
- A61B 5/7282: {Event detection, e.g. detecting unique waveforms indicative of a medical condition (cough events A61B5/0823; seizures A61B5/4094; sleep apnoea A61B5/4818)}
- A61B 5/746: {Alarms related to a physiological condition, e.g. details of setting alarm thresholds or avoiding false alarms}
- A61N 1/3627: {for treating a mechanical deficiency of the heart, e.g. congestive heart failure or cardiomyopathy}
- A61N 1/36585: {controlled by two or more physical parameters}
- G16H 40/63: for local operation
- G16H 40/67: for remote operation
- G16H 50/20: for computer-aided diagnosis, e.g. based on medical expert systems
- G16H 50/30: for calculating health indices; for individual health risk assessment
- A61B 5/0816: {Measuring devices for examining respiratory frequency (measuring frequency of electric signals G01R23/00)}
- A61B 7/04: Electric stethoscopes
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)
- A61N: ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY (measurement of bioelectric currents A61B; surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body A61B18/00; anaesthetic apparatus in general A61M; incandescent lamps H01K; infrared radiators for heating H05B)
- G16H: HEALTHCARE INFORMATICS, i.e. INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR THE HANDLING OR PROCESSING OF MEDICAL OR HEALTHCARE DATA

## Abstract

Systems and methods for detecting worsening cardiac conditions such as worsening heart failure events are described. A system may include sensor circuits to sense physiological signals and signal processors to generate from the physiological signals first and second signal metrics. The system may include a risk stratifier circuit to produce a cardiac risk indication. The system may use at least the first signal metric to generate a primary detection indication, and use at least the second signal metric and the risk indication to generate a secondary detection indication. The risk indication may be used to modulate the second signal metric. A detector circuit may detect the worsening cardiac event using the primary and secondary detection indications.

## Claims

### Claim 1

A system for detecting a worsening cardiac event in a patient, comprising:
sensor circuits including sense amplifier circuits to sense a first physiological signal and a second physiological signal;
a signal processor circuit configured to generate a first signal metric from the first physiological signal and a second signal metric from the second physiological signal;
a risk stratifier circuit configured to produce a risk indication indicating a risk of the patient developing a future worsening cardiac event; and
a detector circuit coupled to the signal processor circuit and the risk stratifier circuit, the detector circuit configured to:
generate a primary detection indication using at least the first signal metric;
generate a secondary detection indication using at least the second signal metric and the risk indication; and
detect the worsening cardiac event using the primary and secondary detection indications; and
an output circuit configured to generate an alert in response to the detection of the worsening cardiac event.

### Claim 2 (depends on 1)

The system of claim 1, further comprising a therapy circuit configured to deliver a therapy in response to the detection of the worsening cardiac event.

### Claim 3 (depends on 1)

The system of claim 1, wherein the first signal metric includes a heart sound signal metric and the second signal metric includes a respiratory signal metric,
wherein the heart sound signal metric includes a third heart sound (S3) intensity or a ratio of a third heart sound (S3) intensity to a reference heart sound intensity; and
wherein the respiratory signal metric includes a respiration rate measurement, a tidal volume measurement, or a ratio of the respiration rate to the tidal volume measurement.

### Claim 4 (depends on 1)

The system of claim 1, wherein the detector circuit is configured to detect the worsening cardiac event using a decision tree including the primary and secondary detection indications,
wherein secondary detection indication is generated based on a sub-decision tree included in the decision tree, the sub-decision tree including the risk indication and a detection based on at least the second signal metric.

### Claim 5 (depends on 4)

The system of claim 4, wherein the sensor circuits further includes a third sense amplifier circuit to sense a third physiological signal, and the sub-decision tree further includes a detection based on the third physiological signal; and
wherein the detector circuit is configured to:
if the decision based on the second physiological signal indicates a detection of the worsening cardiac event, generate the secondary detection indication using the risk indication; or
if the decision based on the second physiological signal indicates no detection of the worsening cardiac event, generate the secondary detection indication using the detection based on the third physiological signal.

### Claim 6 (depends on 1)

The system of claim 1, wherein:
at least one of the primary or secondary detection indication includes a Boolean-logic or fuzzy-logic combination of two or more signal metrics; or
the risk indication includes a Boolean-logic or fuzzy-logic combination of two or more risk indications.

### Claim 7 (depends on 1)

The system of claim 1, wherein the detector circuit is configured to:
generate a composite signal trend using a combination of the first signal metric and the second signal metric modulated by the risk indication; and
detect the worsening cardiac event in response to the composite signal trend satisfying a specified condition.

### Claim 8 (depends on 7)

The system of claim 7, wherein the composite signal trend includes a linear combination of a temporal change of the first signal metric and a temporal change of the second signal metric modulated by the risk indication, the modulated second signal metric including:
the temporal change of the second signal metric weighted by the risk indication; or
the temporal change of the second signal metric sampled when the risk indication satisfies a specified condition.

### Claim 9

A system for identifying a patient's risk of developing a future worsening cardiac disease, the system comprising:
sensor circuits including sense amplifier circuits to sense first, second, and third physiological signals;
a signal processor circuit configured to generate a first signal metric from the first physiological signal, a second signal metric from the second physiological signal, and a third signal metric from the second physiological signal;
a risk stratifier circuit coupled to the signal processor circuit, the risk stratifier circuit configured to:
generate a primary cardiac risk indication using at least the first signal metric;
generate a secondary cardiac risk indication using at least the second and third signal metrics; and
generate a composite cardiac risk indication using both the primary and secondary cardiac risk indications; and
an output circuit configured to provide the composite cardiac risk indication to a clinician or a process.

### Claim 10 (depends on 9)

The system of claim 9, wherein the risk stratifier circuit is to generate a secondary cardiac risk indication using a plurality of measurements of the second signal metric during a time period when the third signal metric satisfies a specified condition.

### Claim 11 (depends on 9)

The system of claim 9, wherein:
the signal processor circuit is to generate a first plurality of measurements of the first signal metric and a second plurality of measurements of the second signal metric; and
the risk stratifier circuit is to:
generate the primary cardiac risk indication including a first statistic of the first plurality of measurements of the first signal metric, and the secondary cardiac risk indication including a second statistic of the second plurality of measurements of the second signal metric; and
generate the composite cardiac risk indication using a combination of the first statistic of the first signal metric and the second statistic of the second signal metric.

### Claim 12 (depends on 9)

The system of claim 9, further comprising a fusion model selector circuit configured to select a fusion model from a plurality of candidate fusion models based on signal quality of the first, second, and third physiological signals,
wherein the risk stratifier circuit is configured to generate the composite cardiac risk indication using both the primary and secondary cardiac risk indications according to the selected fusion model.

### Claim 13

A method for detecting a worsening cardiac event in a patient, comprising:
sensing, via sensor circuits, first and second physiological signals;
generating a first signal metric from the first physiological signal and a second signal metric from the second physiological signal;
producing a risk indication indicating a risk of the patient developing a future worsening cardiac event;
generating a primary detection indication using at least the first signal metric, and a secondary detection indication using at least the second signal metric and the risk indication; and
detecting the worsening cardiac event using the primary and secondary detection indications.

### Claim 14 (depends on 13)

The method of claim 13, wherein detecting the worsening cardiac event includes using a decision tree based on the primary and secondary detection indications,
wherein the decision tree includes a sub-decision tree based on the risk indication and a detection based on at least the second signal metric.

### Claim 15 (depends on 14)

The method of claim 14, wherein:
at least one of the primary or secondary detection indication includes a Boolean-logic or fuzzy-logic combination of two or more signal metrics; or
the risk indication includes a Boolean-logic or fuzzy-logic combination of two or more risk indications.

### Claim 16 (depends on 14)

The method of claim 14, further comprising generating a composite signal trend using a combination of the first signal metric and the second signal metric modulated by the risk indication, wherein the worsening cardiac event is detected in response to the composite signal trend satisfying a specified condition.

### Claim 17 (depends on 16)

The method of claim 16, wherein the modulation of the second signal metric includes a scaled temporal change of the second signal metric weighted by the risk indication, or a sampled temporal change of the second signal metric when the risk indication satisfies a specified condition.

### Claim 18 (depends on 13)

The method of claim 13, wherein producing the risk indication includes:
generating a primary cardiac risk indication using at least a first signal metric for cardiac risk assessment;
generating a secondary cardiac risk indication using at least second and third signal metrics for cardiac risk assessment; and
generating a composite cardiac risk indication using both the primary and secondary cardiac risk indications.

### Claim 19 (depends on 18)

The method of claim 18, wherein generating the secondary cardiac risk indication includes taking a plurality of measurements of the second signal metric during a time period when the third signal metric satisfies a specified condition.

### Claim 20 (depends on 18)

The method of claim 18, wherein producing the risk indication further includes transforming the composite cardiac risk indication using a sigmoid function.