Abstract:
Blood pressure recordings are among the most frequently used parameters in clinical practice to assess cardiovascular status, performance and disease. At present, the only way to accurately measure pressure in the left ventricle (LV) is invasively, via cardiac catheterisation. Echocardiography is the workhorse of cardiac imaging and is widely available. Currently in the clinic, pressure gradients are estimated non-invasively using 2D + time echocardiography, which uses an approach that is known to overestimate the ventricular pressures. New innovative methods are being developed to estimate LV pressure non-invasively by recording full-field velocity using research tools such as phase-contrast magnetic resonance imaging and 4D flow echocardiography. However, these methods are not currently available in the clinic due to cost and time consumption. This thesis investigated state-of-the-art methods used to estimate chamber pressures. An experimental study was conducted in a well-controlled laboratory environment to investigate the viability of using fluid pressure recordings in conjunction with 2D + time Doppler ultrasound images as a non-invasive surrogate for catheterisation recordings. The study was conducted using physical phantoms to mimic aortic regurgitation under continuous and pulsatile flow. Based on the results from these laboratory studies, an alternative approach was developed to estimate the chamber pressure with 2D + time echocardiography using conservation of energy principles. This alternative method could potentially be viable for use in the clinic to estimate pressures in chambers of hearts with abnormalities related to regurgitation and stenosis. Such new technology would assist with non-invasive detection of cardiovascular disease.
