A. Belardinelli

An automatic procedure to convert ECGs from graph paper to digital signals

Today most commercial equipment already provides ECG signals in a digital form and allow their registration in a local archive. However, the recovery of past ECGs from graph paper is still needed since ECGs are a valuable source of information regarding the clinical history of a patient and, consequently, it is very useful to have all the ECG recordings of the same patient in the same digital archive for subsequent analyses and comparisons. In this paper we propose a new method to convert ECGs from graph paper to digital signals. First a digital image of the ECG on graph paper is obtained with a flatbed scanner (600 dpi) and then a line detection procedure is used to detect and locate the ECG trace. The first order absolute moment (FOAM) is used as a mathematical operator to highlight the ECG trace with a ridge and the ECG signal is subsequently located at the top of the ridge with a multi-resolution approach.

The effect of mitral annuloplasty on left ventricular regional diastolic function: a finite element model

The surgical procedure of mitral valve repair is often accompanied by the insertion of a semirigid or flexible annular ring. An important effect of the insertion of small rings is a major reduction of the chamber volume and then a better ventricular performance. To evaluate this effect, a finite element model of the left ventricle has been developed. The geometry of the 3D ventricular structure has been modelled with a truncated ellipsoid. The diastolic mechanical properties of the ventricular walls have been modelled by means of a nonlinear isotropic hyperelastic material; the parameters of the constitutive equations have been chosen on the basis of the expected end diastolic pressure-volume relations. The simulations showed a reduction in the end diastolic volumes with an increase in diastolic wall stress in the equatorial and basal regions. The results suggest that a tailored annuloplasty results to be more effective.

A computerized multiparametric approach for the evaluation of cardiovascular risk in hypertensive patients

In order to evaluate the factor of cardiovascular risk in hypertensive patients, the most common measured physiological parameter is the arterial blood pressure (BP), often leaving out of considerations other important cardiovascular parameters, such as mechanical arterial compliance. To better evaluate the inherent variability of blood pressure, with respect to the control of cardiovascular system and situational determinants, a computerised system has been developed. By means of a PC, equipped with a 12 bits A/D board, BP, heart rate patient voice and posture and external temperature have been acquired. The systolic, diastolic, and mean values of BP and the heart rate have been continuously, beat-to-beat, acquired with a Finapres, while ad hoc developed sensors have been used to acquire the other parameters. The signals, acquired in the different detected situations, have been processed by means of a software developed in LabView environment. A linear regression of systolic blood pressure and RR interval in agreement with the Karemaker equation, is carried out, evaluating the baroceptorial system sensitivity. The developed system may be usefully exploited in the investigation of the baroceptorial reflex and the of control mechanism of cardiovascular system. Moreover, the multiparametric accomplished analysis method could be used in the evaluation and in the setting up of pharmacological interventions.