Abstract 8772: Clinical Correlates of Pulmonary Artery Pulse Wave Velocity in Normal Subjects

Abstract

Background: In contrast to systemic artery, much less is known about age-related change in pulmonary artery stiffness. Pulse wave velocity (PWV) is an index for vascular stiffness. The purpose of this study is to assess pulmonary artery PWV and investigate their relations to age, body mass index (BMI), pulmonary artery systolic pressure, left ventricular (LV) diastolic pressure, and systemic artery PWV in normal subjects. Methods: Echocardiography with tissue Doppler imaging was performed in 92 normal subjects from 6 to 80 years. To measure pulmonary artery PWV, pulsed Doppler flow wave transmission time (T) between main pulmonary artery proximal (pulmonary valve) and distal point (pulmonary artery bifurcation) were measured. The distance (D) from the pulsed Doppler sample volume in the pulmonary valve to the pulmonary artery bifurcation was measured. The pulmonary artery PWV was defined as T/D. Pulmonary artery systolic pressure was calculated by use of the modified Bernoulli equation, with right atrial pressure assumed to be 10 mmHg. The ratio of early transmitral flow velocity (E) to early mitral annular myocardial velocity (Em) was used as an echocardiography-derived estimate of LV diastolic pressure. Results: Average value of pulmonary artery PWV was 179±58 cm/sec (range: 78 to 450cm/sec), in good agreement with literature values measured using invasive means. Pulmonary artery PWV did not correlate with heart rate. There were significant relationships between pulmonary artery PWV and age (r = 0.69, p < 0.01), body mass index (r = 0.46, p < 0.01), and pulmonary artery systolic pressure (r = 0.54, p < 0.01). A weak but significant relationship between systemic arterial PWV and pulmonary artery PWV was observed (r = 0.38, p < 0.01). There was no significant relationship between pulmonary artery PWV and mitral E/Em. Conclusions: We provide the first evidence of age-related increase in pulmonary artery pulse wave velocity, its association with increasing pulmonary artery systolic pressure and systemic vascular stiffening, and its negative impact on body mass index. Pulmonary artery pulse wave velocity may serve as a novel cardiovascular risk factor.