University of TehranSchool of Electrical and Computer

Engineering

ISSCC 2013

Intra-Cardiac Signal-Processing IC

Spring 2013

 by:Yasser Rezaeiyan

 

Sunyoung Kim et al, "A 20µW intra-cardiac signal-processing IC with 82dB bio-impedance measurement dynamic range and analog feature extraction for ventricular fibrillation detection," Solid-State Circuits Conference Digest of Technical Papers (ISSCC), 2013 IEEE International , vol., no., pp.302,303, 17-21 Feb. 2013

Cardiac biologic system

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Time, ms

Volta

ge, m

V

S–T elevation

ECG

Intracardiac electrogram

J.G. Webster,”Design of Cardiac Pacemaker” , IEEE PRESS 1998. 1/12

Importance of Intra-Cardiac SPThe accurate recognition of multiple intra-

cardiac signals is becoming more and more important for:Cardiac Resynchronization Therapy (CRT)the analysis of the intra-thoracic fluid status

But for Cardiac pacemakerRobust and accurate heart rate (HR) at the

right/left ventricles and right atriumBut for the intra-cardiac rhythm analysis

accurate motion sensorthoracic impedance measurement Sunyoung Kim et al, "A 20µW intra-cardiac signal-processing IC with 82dB bio-impedance measurement dynamic range

and analog feature extraction for ventricular fibrillation detection," Solid-State Circuits Conference Digest of Technical Papers (ISSCC), 2013 IEEE International , vol., no., pp.302,303, 17-21 Feb. 2013J.G. Webster,”Design of Cardiac Pacemaker” , IEEE PRESS 1998. 2/12

Cardiac PacemakerMemory

AV interval timer

Pacing interval timer

Microprocessor

Telemetry Atrial stimulus generator

Atrial sense

Ventricular sense

Ventricular stimulus generator

Data bus

To heart

Implantable Cardiac pacemaker Requirement:Ultra Low Power 7-10 years life timeHigh Accuracy intra cardiac Signal AnalysisSmall System delay < 10 msSmall Size

Sunyoung Kim et al, "A 20µW intra-cardiac signal-processing IC with 82dB bio-impedance measurement dynamic range and analog feature extraction for ventricular fibrillation detection," Solid-State Circuits Conference Digest of Technical Papers (ISSCC), 2013 IEEE International , vol., no., pp.302,303, 17-21 Feb. 2013J.G. Webster,”Design of Cardiac Pacemaker” , IEEE PRESS 1998. 3/12

Analog signal processing IC

It consists of: 3 power-efficient intra-cardiac signal readout channels An ultra-low-power readout circuit for an external accelerometer(RA) Two quadrature bio-impedance readout channels

Digitized sinusoidal current generator

Accurate Wide dynamic range

Sunyoung Kim et al, "A 20µW intra-cardiac signal-processing IC with 82dB bio-impedance measurement dynamic range and analog feature extraction for ventricular fibrillation detection," Solid-State Circuits Conference Digest of Technical Papers (ISSCC), 2013 IEEE International , vol., no., pp.302,303, 17-21 Feb. 2013 4/12

Intra-thoracic fluid analysis requirespurely sinusoidal current source

Resolve bio-impedance down to a mΩ-range change (AC) superimposed on up to a kΩ-range average (DC) impedance

This approach consumes many mWs of powerμW-range power consumption can be

achieved by square-wave current combined with

quadrature demodulation intolerable measurement errors as high as 23%

Sunyoung Kim et al, "A 20µW intra-cardiac signal-processing IC with 82dB bio-impedance measurement dynamic range and analog feature extraction for ventricular fibrillation detection," Solid-State Circuits Conference Digest of Technical Papers (ISSCC), 2013 IEEE International , vol., no., pp.302,303, 17-21 Feb. 2013

5/12

Current Generator16-level quantized-sinusoidal current source

Suppresses all harmonics’ power below the 63rd

harmonic: High resolution with high THD

Low power consumptionBenefits of this approach:

Maximize the power efficiency Mitigate the AC current mismatch Simply adjust the current magnitude (10–

40μAp-p)

Sunyoung Kim et al, "A 20µW intra-cardiac signal-processing IC with 82dB bio-impedance measurement dynamic range and analog feature extraction for ventricular fibrillation detection," Solid-State Circuits Conference Digest of Technical Papers (ISSCC), 2013 IEEE International , vol., no., pp.302,303, 17-21 Feb. 2013 6/12

Bio-impedance readout channel Quadrature demodulation Extract both DC and AC bio-impedance Offset of the QIRC may affect the

accuracy of the DC bio-impedance calculation that resolve with Multi-Purpose Chopper

These offset values are calibrated in the DSP

97% accuracy (THD < 3%)

Sunyoung Kim et al, "A 20µW intra-cardiac signal-processing IC with 82dB bio-impedance measurement dynamic range and analog feature extraction for ventricular fibrillation detection," Solid-State Circuits Conference Digest of Technical Papers (ISSCC), 2013 IEEE International , vol., no., pp.302,303, 17-21 Feb. 2013 7/12

Programmable QRS extraction Consumes only 426nA

Sunyoung Kim et al, "A 20µW intra-cardiac signal-processing IC with 82dB bio-impedance measurement dynamic range and analog feature extraction for ventricular fibrillation detection," Solid-State Circuits Conference Digest of Technical Papers (ISSCC), 2013 IEEE International , vol., no., pp.302,303, 17-21 Feb. 2013 8/12

ConclusionASP IC for

emerging CRT:achieve accuracy-

delay optimization for HR monitoring

programmable QRS feature extractor

Highly accurate ultra-low-power

(only 20μW when all channel are active)

Sunyoung Kim et al, "A 20µW intra-cardiac signal-processing IC with 82dB bio-impedance measurement dynamic range and analog feature extraction for ventricular fibrillation detection," Solid-State Circuits Conference Digest of Technical Papers (ISSCC), 2013 IEEE International , vol., no., pp.302,303, 17-21 Feb. 2013 9/12

Trend Pacemakers Leadless Pacemakers

www.medtronic.com10/12

Refrences Sunyoung Kim et al, "A 20µW intra-cardiac signal-processing IC with 82dB

bio-impedance measurement dynamic range and analog feature extraction for ventricular fibrillation detection," Solid-State Circuits Conference Digest of Technical Papers (ISSCC), 2013 IEEE International , vol., no., pp.302,303, 17-21 Feb. 2013

J.G. Webster,”Design of Cardiac Pacemaker” , IEEE PRESS 1998. www.medtronic.com

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Thanks for your attention

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