Study of Heart Disease and Analysis of PPD Algorithm
m5151117Yumiko Kimezawa
October 28, 2011 RPS 1
Outline
• Previous Work• Modification to Methods• Current PPD Algorithm• My Opinion• Future Work
October 28, 2011 RPS 2
Previous Work
• Studying how to actually capture an ECG signal from people
• An A/D converter included in our daughterboard is unfit for capturing the ECG signal
• An input amplifier will be required because the ECG signal is very weak
October 28, 2011 RPS 3
Modification to Methods
• Capturing an ECG signal from people actually
• We use sample data from database as input data
• Capturing an ECG signal from people actually
October 28, 2011 RPS 4
•Hard•Taking long time
Modification
•Studying only
Current PPD Algorithm
• This algorithm seems to process only ECG signals include typical peaks (P, Q, R, S, T and U)
• This algorithm can not process irregular heart rhythm such as ventricular fibrillation (Vf)
October 28, 2011 RPS 5
Ventricular Fibrillation (VF)
October 28, 2011 RPS 6
ventricle
•Extremely dangerous situation•Deadly arrhythmia•Irregular rhythm•P wave is not found•QRS waves are wide-ranging•Severe decrease in blood pressure and no feeling a pulse
Processing Results of VF
October 28, 2011 RPS 7
PPD algorithm must have
detected peaks incorrectly
On the ventricular fibrillation wave, P waves don’t appear and QRS waves are wide-ranging
My Opinion
• Someone’s heart beats hundreds of thousands of times per day (100,000 times/day)
• In addition to extracting ECG wave form, computers have to support analysis of the wave whether heart is normal or not
• Doctors only have to receive information of patients considered at risk for heart disease
October 28, 2011 RPS 8
It is difficult for doctors to diagnose so many patients
My Opinion
Future Work
• Analysis of PPD algorithm• Optimization of PPD algorithm
October 28, 2011 RPS 9
October 28, 2011 RPS 10
October 28, 2011 RPS 11
MIT:16272
RR Interval
PPD Algorithm MIT Database
0.578s (0.000s - 0.578s) 0.570s (0.000s – 0.570s)
0.984s (0.578s – 1.562s) 0.984s (0.570s – 1.555s)
0.953s (1.562s – 2.516s) 0.953s (1.555s – 2.508s)
0.961s (2.516s – 3.477s) 0.969s (2.508s – 3.477s)
0.953s (3.477s – 4.430s) 0.953s (3.477s – 4.430s)
0.969s (4.430s – 5.398s) 0.961s (4.430s – 5.391s)
0.969s (5.398s – 6.367s) 0.977s (5.391s – 6.367s)
0.992s (6.367s – 7.359s) 0.984s (6.367s – 7.352s)
0.961s (7.359s – 8.320s) 0.969s (7.352s – 8.320s)
0.984s (8.320s – 9.305s)
October 28, 2011 RPS 12
MIT:16273
RR Interval
PPD Algorithm MIT Database
0.086s (0.000s - 0.086s) 0.070s (0.000s – 0.070s)
0.609s (0.086s – 0.695s) 0.609s (0.070s – 0.680s)
0.602s (0.695s – 1.297s) 0.602s (0.680s – 1.281s)
0.602s (1.297s – 1.898s) 0.602s (1.281s – 1.883s)
0.609s (1.898s – 2.508s) 0.609s (1.883s – 2.492s)
0.609s (2.508s – 3.117s) 0.609s (2.492s – 3.102s)
0.617s (3.117s – 3.734s) 0.617s (3.102s – 3.719s)
0.633s (3.734s – 4.367s) 0.633s (3.719s – 4.352s)
0.656s (4.367s – 5.023s) 0.656s (4.352s – 5.008s)
0.641s (5.023s – 5.664s) 0.641s (5.008s – 5.648s)
0.641s (5.664s – 6.305s) 0.633s (5.648s – 6.281s)
0.617s (6.305s – 6.922s) 0.625s (6.281s – 6.906s)
0.633s (6.922s – 7.555s) 0.633s (6.906s – 7.539s)
0.617s (7.539s – 8.156s)
0.625s (8.156s – 8.781s)
0.617s (8.781s – 9.398s)
October 28, 2011 RPS 13
MIT:16273
RR Interval
PPD Algorithm MIT Database
0.086s (0.000s - 0.086s) 0.070s (0.000s – 0.070s)
0.609s (0.086s – 0.695s) 0.609s (0.070s – 0.680s)
0.602s (0.695s – 1.297s) 0.602s (0.680s – 1.281s)
0.602s (1.297s – 1.898s) 0.602s (1.281s – 1.883s)
0.609s (1.898s – 2.508s) 0.609s (1.883s – 2.492s)
0.609s (2.508s – 3.117s) 0.609s (2.492s – 3.102s)
0.617s (3.117s – 3.734s) 0.617s (3.102s – 3.719s)
0.633s (3.734s – 4.367s) 0.633s (3.719s – 4.352s)
0.656s (4.367s – 5.023s) 0.656s (4.352s – 5.008s)
0.641s (5.023s – 5.664s) 0.641s (5.008s – 5.648s)
0.641s (5.664s – 6.305s) 0.633s (5.648s – 6.281s)
0.617s (6.305s – 6.922s) 0.625s (6.281s – 6.906s)
0.633s (6.922s – 7.555s) 0.633s (6.906s – 7.539s)
0.617s (7.539s – 8.156s)
0.625s (8.156s – 8.781s)
0.617s (8.781s – 9.398s)
Our Architecture
October 28, 2011 RPS 14
A/Dconverter Filter RAM Processing Results
From patient
Sensor
Processing results are sent through the Ethernet
Important Things in Measurement of ECG Signal
• Clinically-important frequency component of ECG signal- 0 ~ 250Hz
October 28, 2011 RPS 15
• Change in voltage in chest wall- Less than 3mV (very weak)
• Measurement in environments with much noise
Change in voltage inside this range must be faithfully reproduced
Voltage gain of high signal-to-noise ratio (250 to 1000 times) must be gained• Signal-to-noise ratio: The ratio of signal power to the noise power
Book Knowledge
October 28, 2011 RPS 16
Impedance converter
Lead network
Head amplifier
Micro computerADCMain
amplifier
Isolation circuit
Output equipment
Lead Code
Power Circuit
•An example of block diagram illustrating cardiography equipment
Book Knowledge
October 28, 2011 RPS 17
Impedance converter
Lead network
Head amplifier
Micro computerADCMain
amplifier
Isolation circuit
Output equipment
Lead Code
Power Circuit
•An example of block diagram illustrating cardiography equipment
•This circuit prevents body’s impedance from being lower than input circuit’s impedance
Book Knowledge
October 28, 2011 RPS 18
Impedance converter
Lead network
Head amplifier
Micro computerADCMain
amplifier
Isolation circuit
Output equipment
Lead Code
Power Circuit
•An example of block diagram illustrating cardiography equipment
•Constitution of 12-lead from the combination of sensors•A~J : Sensors•Example
- Ⅰ: Output between A and E- aVR: Output between A and F
Book Knowledge
October 28, 2011 RPS 19
Impedance converter
Lead network
Head amplifier
Micro computerADCMain
amplifier
Isolation circuit
Output equipment
Lead Code
Power Circuit
•An example of block diagram illustrating cardiography equipment•ECG signal is very weak
•The signal must not be amplified suddenly
•Differential amplifier is used as head amplifier
An amplifier is needed
The signal is amplified in stages
• Noises are reduced• signal-to-noise ratio is
improved
Book Knowledge
October 28, 2011 RPS 20
Impedance converter
Lead network
Head amplifier
Micro computerADCMain
amplifier
Isolation circuit
Output equipment
Lead Code
Power Circuit
•An example of block diagram illustrating cardiography equipment
•For securing of security, impedance converter, lead network and head amplifier have to be isolated from main amplifier, power circuit and A/D converter
Question•A/D converter (AD9254) is included in HSMC- Pipelined switched capacitor ADC- Sampling frequency: 150MHz- Resolution: 14-bit- Power: 430mW
October 28, 2011 RPS 21
HSMC
Performance is overmuch•Clinically-important frequency component of ECG signal is from 0 to 250Hz
500Hz is enough for sampling frequency
•Using a lot of electricity•Conversion process is complex•Using A/D converter in HSMC is of questionable value
心電計の回路を表すブロック図の例
October 28, 2011 RPS 22
インピーダンス変換器
誘導ネットワーク
前置増幅器
マイクロコンピュータ
AD変換器主増幅器
アイソレーション回路
出力装置
誘導コー
ド電源回路
標準12誘導を作るための誘導ネットワークの原理
October 28, 2011 RPS 23
A
B C D
E
F
G
HI
J
A~Jの各点の出力を組み合わせる。例えば、第Ⅰ誘導は AとE、 aVRは AとFを組み合わせたものとなる。