Portable Heart Attack Detector (PHAD) Final Presentation

1. Supervisor Daniel Alkalay System architectures Nir Gluzman Alexei Iolin Technion - Israel Institute of Technology Department of Electrical Engineering High-Speed Digital Systems Lab Portable HeartAttack Detector(PHAD)Final Presentation 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. PXI-1042Q PXI-7831R 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. (*) website: http://ni.com

4. R T P Q S Basic ECG complex

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. 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 pointsdetection 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 developmentplatform • 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. What is LabVIEW?

16. Synchronizationviainterrupts LabVIEW developmentplatform (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.

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 TPrate 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 ofmechanical engineering System demonstration

28. Questions?