Doppler catheter measurements of blood flow velocity in coronary arteries.
2015-11-19T08:50:30Z (GMT) by
Most heart disease is related to the luminal narrowing of the arteries that supply blood to the heart tissues, the coronary arteries. Coronary arteriography (CA) is regarded as the most accurate method for detecting the presence and severity of coronary disease. Nevertheless, there are some limitations associated with CA. In order to obtain further information on the severity of the stenosis many investigations have been performed with the use of a complementary technique: the intravascular Doppler catheter. Despite its growing use, there are few reported investigations of the errors introduced into velocity estimates obtained using catheter tipped transducers. Velocity estimates are used to calculate parameters which are then correlated with the haemodynamic situation under investigation. This dissertation reports theoretical and experimental investigations carried out to assess the limitations of the technique in obtaining accurate velocity estimates. It also describes a microcomputer based system developed to obtain velocity estimates from Doppler signals sampled from coronary arteries and calculate parameters currently discussed in the literature. To calculate these parameters two other waveforms are sampled and processed: electrocardiogram and pressure. Discussion on digital techniques regarding improvement of the velocity estimates and analysis of Doppler signals is presented. Examples of clinical data obtained with the system developed and calculated parameters are given. Limitations of this technique and clinical procedures based on it are also discussed.