1. Portable Heart Attack Detector (PHAD) Final Presentation
Technion - Israel Institute of Technology
Department of Electrical Engineering
High-Speed Digital Systems Lab
Portable Heart Attack Detector (PHAD) Final Presentation
Supervisor
Daniel Alkalay
System architectures
Nir Gluzman
Alexei Iolin
Nov 27, 2005

2. AGENDA Project objective System block diagram
ECG signal analysis algorithm
Firmware block diagram
LabVIEW development platform
VI blocks and GUI
Summary and conclusions
System demonstration

3. Project objective
Develop a system that detects R characteristic point and measures ST-elevation and QRS duration.
Implement the system on National-Instrument(*) Real-Time FPGA development environment using LabVIEW graphical programming language.
PXI-7831R
PXI-1042Q
(*) website:

4. Basic ECG complex R P Q S T

5. ST Elevation

6. System block diagram

7. ECG signal analysis algorithm
ECG characteristic points are detected with DWT (Discrete Wavelet Transform).
DWT is implemented with “Algorithme à trous” (implementation without decimation).
Source: “A wavelet-based ECG delineator: evaluation on standard databases”, IEEE Transaction on biomedical engineering, April 2004.

8. Why can ECG characteristic points be detected with Wavelet transform?
Algorithm (cont.)
Why can ECG characteristic points be detected with Wavelet transform?
The Wavelet transform (WT) is proportional to the derivative of the filtered version of the signal.
Zero-crossing of the WT corresponds to the local maxima or minima of the filtered signal.
Maximum absolute values of the WT are associated with the maximum slopes in the filtered signal.

9. Algorithm (cont.)
ECG waves are composed of slopes and local maxima or minima.
Therefore, QRS complex produces an unique pattern (max-min-max).

10. ECG characteristic points detection flow chart

11. Q, S detection

12. R detection

13. Firmware block diagram
Algorithm has been implemented in VHDL.
Firmware includes 3 main blocks:
Wavelet decomposition.
d4 signal processing for QRS complex detection and calculation of QRS duration.
ST elevation calculation.

14. Firmware (cont.)
Top level

15. LabVIEW development platform
What is LabVIEW?
Graphical programming language with built-in functions for I/O, control, analysis and data presentation.
LabVIEW advantages:
Intuitive graphical development similar to flowcharting.
Bulit-in tools for design, control, data acquisition and data presentation.

16. LabVIEW development platform (cont.)
Platform includes two independent modules:
LabVIEW for Windows (Host):
 Floating-point calculations.
 Data presentation.
 Off-line data acquisition.
LabVIEW for FPGA:
 Fix-point signal processing.
 Real-time data acquisition.
 VHDL integration.
Synchronization via interrupts

17. VI blocks and GUI
FPGA
Data trans-ceiving between FPGA (signal processing) and host (data presentation) is based on synchronization interrupts.
FPGA synchronization interrupts demands sequential framing operations:
FPGA VI includes three frames:
I/O and signal processing modules (VHDL core).
Sampling time delay.
IRQ to host.
HDL clock is synthesized from ‘while loop’ index’s LSB.

18. VI blocks and GUI (cont.)
FPGA VI

19. VI blocks and GUI (cont.)
Host
Host includes two independent sub VIs:
Test mode for system verification (off-line ECG analyzing).
Real-time controlling mode for analyzing on-line ECG signals.
Host’s GUI graphically presents both sub VIs outputs and controls FPGA module.

20. VI blocks and GUI (cont.)
Test mode VI

21. VI blocks and GUI (cont.)
Real-time controlling mode VI

22. VI blocks and GUI (cont.)
System’s GUI

23. Summary and conclusions
Project involves a system development for a medical application.
The system is based on a firmware implementation for a sophisticate signal processing algorithm (DWT).
ECG real-time DWT analysis is feasible for HW implementation.
This project has familiarized us with new development tools and techniques, such as:
LabVIEW, HDL designer, ModelSim, Matlab/Simulink.
Real-time system development.
HW-SW integration.

24. Summary and conclusions
System performance
Both QRS complex and R characteristic point FP (False Positive = false alarm) rates are very low.
QRS complex TP (True Positive) rate is very high (>95%).
R characteristic point TP rate is lower than in Matlab/Simulink model, because implemented algorithm doesn’t use d2 and d3 (in addition to d4).
System can be used as STEMI detector, because QRS complex TP rate is high enough to detect irregular ST level variations on time.

25. Summary and conclusions
LabVIEW platform advantages
Rapid prototype system.
Dedicated hardware and software.
I/O easy access.

26. Summary and conclusions
LabVIEW platform disadvantages
Development environment is non-conventional - design extraction to other non NI environments is NOT possible.
VHDL code is hidden from user.
Lack of debugging tools.
Unfriendly VHDL interface.
Emulator supports FPGA simulations but doesn’t support IRQ simulation (FPGA-Host data trans-ceiving).

27. The faculty of mechanical engineering
System demonstration
The faculty of mechanical engineering

28. Questions?