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

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

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: http://ni.com

Basic ECG complex R P Q S T

ST Elevation

System block diagram

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.

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.

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

ECG characteristic points detection flow chart

Q, S detection

R detection

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.

Firmware (cont.) Top level

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.

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

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.

VI blocks and GUI (cont.) FPGA VI

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.

VI blocks and GUI (cont.) Test mode VI

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

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

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.

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.

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

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).

The faculty of mechanical engineering System demonstration The faculty of mechanical engineering

Questions?