Hilbert Transform Based Time Signal Displays for Doppler Echo Cardiograms

Abstract

From the echo-Doppler quadrature Signals I and Q of a typical diagnostic ultrasound machine, data processing by using Hilbert Transform enabled the separation of the positive and negative frequency Doppler shift signals as actual typical time-course signals. This provided extra information regarding valve leaflet functioning. Choosing short instants at the T wave fall (Electrocardiogram), the P wave beginning as well the rising edges of the E and A waves (Doppler Spectrogram), such time signals are shown to throw light on the condition of the valves, by means of vibrations typically found in rheumatic mitral valve conditions and even mild mitral stenosis cases. A PC with add on ADC/DSP hardware was used with an ultrasound diagnostic machine in a clinical centre, which enabled the results to be observed on its monitor side by side with the usual B-scan, Colour Doppler and Spectrogram displays on the machine.

Indexing terms:

• Doppler ultrasound echocardiography
• Stenosis of valves
• Blood flow in cardiac chambers
• Regurgitation
• Hilbert Transform

Additional information

Notes on contributors

K Padmanabhan

K Padmanabhan, was born in 1939 in Ramanathapuram. He got his qualifications in Engineering in the University of Madras by 1966 and joined the University Service in 1966 as Reader. Later in 1976, he became Professor of Instrumentation Engg. and he recently retired from service. He has contributed articles on Elec. Engg., Microprocessors and Instrumentation in various Journals and Magazines.

S Dhanasekaran

S Dhanasekharan, was born in 1951 in Virudhunagar. He did his BE and MSc by the year 1975 and worked a while with the University of Madras and by 1981, joined the Technical Teacher Training Centre at Chennai, where he is presently working as a Professor. He subsequently did his PhD also. He has been actively teaching and doing research on Microprocessor technology, Instrumentation and Computer Science.

D Nedumaran

D Nedumaran, was born in 1965 in Alangottai, Mannargudi. He did his MSc from Bharathidasan University and did his MPhil in the Instrumentation Centre of Madras University in 1989. Later, he also worked and got his PhD in Instrumentation from the same University. He has contributed several papers in Instrumentation and he is presently working with Ozonetek Ltd., Chennai as a Research and Development Scientist.

S Ananthi

S Ananthi, was born in 1958 in Thalainayar. She did her Diploma in Electronic Instrumentation in 1977 and worked for a while with the Madras Institute of Technology and later, in 1980, joined the University of Madras as a Technical Officer. She specialised in Microprocessors and has contributed to several practical circuits in the ‘Electronics for You’. She did her BE by part-time in 1988 and later joined in the IISc at Bangalore for her MTech, which she completed by 1994. She completed her PhD recently in 1999. She has done several research topics in Instrumentation. She is a Member of IETE.