Orestis Vardoulis

Learn More
The method used for pulse transit time (PTT) estimation critically affects the accuracy and precision of regional pulse wave velocity (PWV) measurements. Several methods of PTT estimation exist, often yielding substantially different PWV values. Since there is no analytic way to determine PTT in vivo, these methods cannot be validated except by using in(More)
BACKGROUND Left atrial (LA) dilatation is associated with a large variety of cardiac diseases. Current cardiovascular magnetic resonance (CMR) strategies to measure LA volumes are based on multi-breath-hold multi-slice acquisitions, which are time-consuming and susceptible to misregistration. AIM To develop a time-efficient single breath-hold 3D CMR(More)
Total arterial compliance (C T) is a main determinant of cardiac afterload, left ventricular function and arterio-ventricular coupling. C T is physiologically more relevant than regional aortic stiffness. However, direct, in vivo, non-invasive, measurement of C T is not feasible. Several methods for indirect C T estimation require simultaneous recording of(More)
OBJECTIVE Vascular prostheses currently used in vascular surgery do not have the same mechanical properties as human arteries. This computational study analyses the mechanisms by which grafts, placed in the ascending aorta (proximal) and descending aorta (distal), affect arterial blood pressure. METHODS A one-dimensional cardiovascular model was developed(More)
Cardiac output (CO) monitoring is essential for the optimal management of critically ill patients. Several mathematical methods have been proposed for CO estimation based on pressure waveform analysis. Most of them depend on invasive recording of blood pressure and require repeated calibrations, and they suffer from decreased accuracy under specific(More)
Glaucoma results in an increase in the resistance of the aqueous humor outflow, which in turn leads to an increase of the intraocular pressure (IOP). Several treatments are proposed to reduce and stabilize the IOP that include medications, filtering surgery and glaucoma drainage devices (GDD). So far computational fluid dynamics (CFD) modeling of the eye(More)
We introduce a novel variational framework for the regularized reconstruction of time-resolved volumetric flow fields. Our objective functional takes the physical characteristics of the underlying flow into account in both the spatial and the temporal domains. For an efficient minimization of the objective functional, we apply a proximal-splitting algorithm(More)
We propose a new variational framework for the problem of reconstructing flow fields from noisy measurements. The formalism is based on regularizers penalizing the singular values of the Jacobian of the field. Specifically, we rely on the nuclear norm. Our method is invariant with respect to fundamental transformations and can be efficiently solved. We(More)
Recent advance in imaging modalities used frequently in clinical routine can provide description of the geometrical and hemodynamical properties of the arterial tree in great detail. The combination of such information with models of blood flow of the arterial tree can provide further information, such as details in pressure and flow waves or details in the(More)
Gaddum et al., recently published in Annals of Biomedical Engineering an interesting article seeking the optimal method for the estimation of arterial pulse transit time (TT) between two arterial sites. Accurate and precise TT estimation in vivo is a critical issue, because TT is one of the two parameters (together with distance measurement) needed for the(More)