Session P34.3

An Automatic Brachial Ankle Pulse Wave Velocity Measurements for Vascular Damage Assessments

R Gonzalez*, O Morales, J Delgado, JM Padilla,
J Saiz, JM Ferrero

Universitat Politècnica de València
Valencia, Spain

The pulse wave velocity is the velocity of a pulse wave travelling a given distance between two sites in the arterial system. It involves taking recordings from the two sites simultaneously, or gating separate recordings to a fixed point in the cardiac cycle, usually the R wave of ECG. Generally, the time interval of pulse wave velocity is determined by the foot-to-foot pulse wave. In people with diagnosed cardiovascular diseases, the shape of waveform could be irregular, making the automatic pulse wave velocity measurements non consistent.
The aim of this work is to increase the accuracy of automatic brachial ankle pulse wave velocity measurements by using the maximal time derivative point of waveform rather than foot-to-foot pulse wave as time interval.
An automatic brachial ankle pulse wave velocity device was developed using plethysmographic method based on blood pressure cuffs wrapped on arm brachial artery and tibial artery of ankle. Four electrodes of electrocardiogram were placed on ventral surface of both wrists and medial side of ankles. The acquired signals of volume pulse and ECG were displayed. The time interval between brachial and ankle was calculated as the time difference between maximal time derivative points and foot-to-foot pulse waves originated by the same QRS complex. The distance between sampling points of brachial ankle pulse wave velocity was calculated according to the height of the subject using a mathematical approach. This distance divided by the time interval is the pulse wave velocity. In this work a study was carried out for evaluating the usefulness of these brachial ankle pulse wave velocity measurements with 39 people, 22 healthy volunteers and 17 patients with diagnosed cardiovascular diseases as hypertension, atherosclerosis or diabetes mellitus. After the volunteers and patients had rested in a supine position at least 5 min, eight brachial ankle pulse wave velocity measurements ( four for maximal time derivative points and four for foot-to-foot pulse waves ) were measured by subject.
A t-tested distribution of brachial ankle pulse wave velocity was performed between healthy volunteers and patients using maximal time derivative. It had shown a significant difference ( 7.16 vs 15.08 m/sec, p< 0.0001 ). A second t-tested distribution was performed using foot-to-foot pulse waves. It showed a significant difference ( 8.08 vs 19.18 m/sec, p< 0.0001 ). However, the variance in patients measurements using foot-to-foot pulse wave was found to be higher than using maximal time derivative ( 26.25 vs 12.3 ) and also for healthy volunteers ( 1.14 vs 0.32 ).
In conclusion, automatic brachial ankle pulse wave velocity measurements using maximal time derivative showed to be more accurate than foot-to-foot pulse wave both in patients with cardiovascular disease and in healthy volunteers.

(Abstract Control Number: 236)