1. Continuous Wave Doppler Device Group 16: Abbas Bandukwala Padma Chunduru Chris Harvey Advisor: Dr. Raul Guzman

2. Project Objective Design, build and test a system to measure Doppler velocity waveforms in ankle blood vessels Design, build and test a system to measure Doppler velocity waveforms in ankle blood vessels Improve current technology Improve current technology Better signal quality Better signal quality Easier measurement Easier measurement

3. Peripheral Vascular Disease (PVD) Definition: restriction of blood flow to limbs due to narrowing or clogging of arteries Definition: restriction of blood flow to limbs due to narrowing or clogging of arteries Causes Causes Common vascular diseases Common vascular diseases Artherosclerosis, aneurysms, venous thrombosis Artherosclerosis, aneurysms, venous thrombosis Distort normal blood pressure and flow Distort normal blood pressure and flow At risk populations At risk populations >50 years old >50 years old Smokers Smokers Diabetics Diabetics High blood pressure or high cholesterol High blood pressure or high cholesterol

4. Peripheral Vascular Disease (PVD) Incidence of PVD Incidence of PVD 1 in 20 people >50 years old = ~10 million people 1 in 20 people >50 years old = ~10 million people 75% of cases go undiagnosed 75% of cases go undiagnosed Importance of Diagnosis Importance of Diagnosis PVD is a strong predictor of heart disease PVD is a strong predictor of heart disease PVD patients are at a higher risk of stroke and heart disease PVD patients are at a higher risk of stroke and heart disease

5. Noninvasive Vascular Disease Diagnosis Disease diagnosis using noninvasive techniques Disease diagnosis using noninvasive techniques Check for presence, location, severity of disease Check for presence, location, severity of disease External diagnosis is quick, noninvasive External diagnosis is quick, noninvasive Screen high-risk patient populations Screen high-risk patient populations Goal: reduce the number of undiagnosed cases of PVD Goal: reduce the number of undiagnosed cases of PVD ~50 screenings/month or ~600 screenings/year at the Vanderbilt University Vascular Lab ~50 screenings/month or ~600 screenings/year at the Vanderbilt University Vascular Lab

6. Noninvasive Measurement Blood pressure cuff occlusion technique Blood pressure cuff occlusion technique Doppler velocity waveforms are measured at DP and PT arteries in ankle Doppler velocity waveforms are measured at DP and PT arteries in ankle

7. medicine.ucsd.edu/clinicalmed/ extremities.htm www.curtin.edu.au/.../podiatry / encyclopedia/vasdisease/ For the DP, the pulse felt on the top of the foot, between the first and second metatarsal bones. In 8 to 10 per cent of the population this pulse cannot be detected. (www.WebMD.com) For the DP, the pulse felt on the top of the foot, between the first and second metatarsal bones. In 8 to 10 per cent of the population this pulse cannot be detected. (www.WebMD.com) Noninvasive Measurement for DP

8. http:// www.csuchico.edu/phed/atc/Foot/PostTibArtery.jpg Noninvasive Measurement for PT

9. Doppler Velocity Waveforms Triphasic, Normal Biphasic, Abnormal Monophasic, Abnormal

10. Doppler Theory Measures velocity Measures velocity 2 piezoelectric crystals 2 piezoelectric crystals Transmitting, receiving Transmitting, receiving Change in frequency due to movement of red blood cells Change in frequency due to movement of red blood cells Crystals RBC Blood Flow

11. Current Technology Advantages/Disadvantages Advantages/Disadvantages Hard to locate proper vein or artery if blood velocity is low. Hard to locate proper vein or artery if blood velocity is low. Must train person to use device. Must train person to use device. User hand tied down with device User hand tied down with device Device is compatible with all persons. Device is compatible with all persons.

12. Advantages of Doppler Array Cheap because it does not require trained crew Cheap because it does not require trained crew Easier to find signal Easier to find signal Works on a high percentage of the population Works on a high percentage of the population Universality of device Universality of device User is able to perform multiple functions User is able to perform multiple functions

13. Parts Doppler crystal array ($45/crystal) Doppler crystal array ($45/crystal) Doppler pens ($100/pen) Doppler pens ($100/pen) Computer Computer Connectors (~$25/crystal) Connectors (~$25/crystal) A/D Converter A/D Converter LabView LabView An Ace bandage Doppler Gel Doppler Audio Amplifier Oscilloscope Power supply Op-amps, resistors, capacitors Breadboard

14. How we are going to go about solving the problem? Ace Bandage Piezoelectric Crystals Data Acquisitio n & Analysis High Pass & Amplifier circuit Power Supply

15. Past Work Investigation into the use of Doppler as a means of vascular disease diagnosis Investigation into the use of Doppler as a means of vascular disease diagnosis Research on the equipment necessary for data acquisition Research on the equipment necessary for data acquisition Acquisition of equipment Acquisition of equipment Design of High Pass filter and Amplifier to increase SNR Design of High Pass filter and Amplifier to increase SNR Signal (waveform) displayed on LabView Signal (waveform) displayed on LabView

16. Current Status Acquisition of signal from Doppler crystal Acquisition of signal from Doppler crystal high pass filter high pass filter Amplifier Amplifier Doppler Crystal High Pass Filter Amplifier Signal In Speaker Out Audio Doppler Box Oscilloscope on LabView

17. Current Status Development of LabView program Development of LabView program Input of audio Doppler output Input of audio Doppler output Display of signal on an oscilloscope in LabView Display of signal on an oscilloscope in LabView Recording of data for analysis (of signal quality) Recording of data for analysis (of signal quality) Highest Amplitude Highest Amplitude Do not need a Demultiplexer Do not need a Demultiplexer Change in frequency not necessary for diagnosis Change in frequency not necessary for diagnosis Doppler Crystal High Pass Filter Amplifier Signal In Speaker Out Audio Doppler Box Oscilloscope on LabView

18. Future Test data acquisition with LabView Test data acquisition with LabView Pencil probes Pencil probes Picking the signal with the highest amplitude from multiple inputs Picking the signal with the highest amplitude from multiple inputs Working on crystals that can give signal and can eventually be incorporated into an array Working on crystals that can give signal and can eventually be incorporated into an array Increase sensitivity so the input signal can be perceived Increase sensitivity so the input signal can be perceived