The prototype system consists of the following major components:
System Block Diagram
Signals are initially picked up from the heart (or from a simulator) by an especially designed catheter
These signals are then transferred to an amplification unit via a junction box
The amplification unit then removes common sources of noise and filters any offset that may be present
The processed signals are then transferred to a PC using a Data Acquisition Unit (DAQ)
On the PC, the signals can then be viewed using software developed during the ISAAD project or transferred over to the telemedicine system
ISAAD software was developed in LabVIEW due to its superior hardware-software integration features and the ease of building noise removal filters, analyzing signals and communicating with networks using this tool. The program has been developed for a two-monitor user environment.
The program was built to include the following main features:
Signal acquisition using a DAQ card
Band-pass filtering (for baseline removal and high frequency noise)
Notch filtering (for Power Line Interference (PLI) removal).
Display of the ICEG signals
Analysis of the ICEG signals
AN EARLY VERSION OF THE ISAAD SOFTWARE
An Early Version of the ISAAD Software
The program allows for the recording of several hours of IECG and standard ECG signals. A live display of the signals being received is also shown. At any point in time, a user can rewind the display to view abnormalities or important features in the recorded signals. Recorded signals are also saved in a format suitable for use with MATLAB software for further analysis.
Left: Live Signal View. Right: Recorded Signal View
Power Line Interference (PLI) is removed by the software using an algorithm developed over the course of the project:
Results of the PLI Removal Algorithm
The software is also capable of detecting QRS points in ECG signals and calculating the vent rate by using the locations of R peaks in the signal.
PQRST Sections of an ECG Signal
Vent Rate Display
AV nodal reentrant tachycardia (AVNRT), or atrioventricular nodal reentrant tachycardia, is a type of tachycardia (fast rhythm) of the heart. The ISAAD software is capable of analyzing signals from the heart to detect the condition in patients:
HISP with A, V, and H measured
Analog Front End (AFE) hardware was developed during this project as an alternative to currently available solutions on the market.Intracardiac signals are very sensitive signals and carry noise in their raw form. In order to make these signals stong and perform noise cancellation a 16-channel amplication and filteration board was developed for the prototype.
Output of the AFE Unit
Below is an outline of the way in which the telemedicine system interfaces with the IECG signal generated by the ISAAD project.
There are two major parts of telemedicine system. The first is the local area network (i.e. the network within the hospital or facility). This network allows doctors within the hospital to view the signals on their Laptops, PDA’s and other smart devices using a developed portal. A LAN or Wi-Fi router can be utilized to create this local area connection.
The second part of this system communicated over the internet. Using a dedicated portal, doctors worldwide can view and analyze signals.
Like the software developed by ISAAD the application used by the telemedicine system was also developed in LabVIEW. As a result, this module was easily incorporated into the system.
The Telemedicine Module
The Intracardiac data in lab view is written into a text file and then it is send through telemedicine system to central server. Then this data can be viewed on any laptop, computer or PDA using a dedicated application.