Reflected pressure waves and flow patterns in open and occluded grafts and coronaries-model study

Atherosclerotic coronary artery disease is the most common cause of myocardial ischemia and the underlying reason for acute coronary syndromes including myocardial infraction. Correcting procedures of blockages such as angioplasty and bypass surgery are common. However, a reliable method for quantifying regional myocardial perfusion and coronary vascular reserve in man has not yet been developed. Assessment of coronary and graft stenosis is still obtained mainly by coronary angiography. This study presents a new model approach and technique to measure the severity of occluded arteries and grafts by measuring the reflected waves from the blocked region. The severity of the occlusion is analyzed using the cepstrum signal processing method. The cepstrum method was analytically formulated and then evaluated experimentally with a hydrodynamic model that simulated pressure waves in arteries. Pressure waves were sampled for varying degrees of occlusions at different distances from the measuring site. The measured results prove the method to be correct in estimating the severity of the occlusion and its location in the artery. Selected experimental results are presented to exhibit the technique.