Biomedical subjects

P Ciarlini

Publications and source records attributed to P Ciarlini.

4 recordsLinked to original sources

PubMed1998

Dependence of temporal variability of ventricular recovery on myocardial fibrosis. Role of mechanoelectric feedback?

OBJECTIVE: The study was aimed at establishing the effect of factors involved in the expression of mechanoelectric feedback in the heart, such as R-R interval and connective tissue, on time dependent changes in ventricular recovery, as determined at the body surface by beat to beat variability of QRST integral maps (BBV-IM). METHODS: We used 15 normal 6-month-old Wistar rats. In each anesthetized animal, we performed a 3-minute continuous recording of 44. The simultaneous chest ECGs. The signals were interactively processed, 1) to determine mean R-R interval and R-R variability throughout the recording period and 2) to compute QRST integral maps from approximately 50 beats belonging to the end of expiration. Then BBV-IM was calculated and expressed as percentage of beats significantly differing from a template. At sacrifice, the amount of myocardial fibrosis was morphometrically evaluated. RESULTS: R-R interval was 149 ms +/- 4, R-R interval variability 0.008 +/- 0.001 and BBV-IM 30.7% +/- 4.4. Myocardial fibrosis expressed as % volume of left ventricular myocardium, numerical density of fibrotic foci and average cross-sectional area of the foci was 3.0% +/- 0.4, 3.8 +/- 0.6 and 4.4 microns(2)/1000 +/- 0.1 respectively, BB-IM was positively correlated to the % volume of fibrosis (r = 0.83, P < 0.0003). Both measurements were positively correlated to R-R interval (BBV-IM: r = 0.83, P < 0.0001; % volume of fibrosis: r = 0.87, P < 0.001) and negatively correlated to cardiac weights (BBV-IM: r = -0.79, P < 0.0005; % volume of fibrosis: r = -0.75, P < 0.001). CONCLUSION: Beat to beat changes in ventricular repolarization attributable to mechanoelectric transduction can be detected at the body surface by means of BBV-IM.

Analysis of Variance↗

PubMed1989

Comparison of electrocardiographic data (P waves): test of a shape-based approach.

We tested a method for comparing ECG signals (P waves), in a sample of 10 normal males. In each subject, sets of 219 body surface ECGs were simultaneously recorded during tidal respiration. Only beats at end expiration and peak inspiration were considered. The beats of each group were subdivided into two subgroups of the same size (about 30 beats) and separately averaged. The two averaged beats at end expiration, assumed to be equal, were compared in order to estimate the noise variance (sigma2), i.e., the lowest value of variance at which the beats were statistically similar (P less than 0.05). At the same value of sigma2, the beat at end expiration significantly differed from that at peak inspiration. By considering the individual leads, significant differences were found in more than 50% of the 219 ECGs, in specific thoracic areas. The data indicated that the method can reveal differences between P waves occurring during tidal respiration and provide information on the topographical distribution of the differences.

Adult↗

PubMed1988

A recursive algorithm to compute the baseline drift in recorded biological signals.

Baseline estimation and removal is one of the main problems to overcome in order to obtain a correct interpretation of recorded biological signals. The method described in this paper is based on a new application of recursive estimation of a smoothing spline, selected to model the unknown baseline. Its advantages over conventional methods derive from these characteristics: it is parametric and recursive, it works in the time domain, and the same software can be used in different applications, since no a priori frequency knowledge is needed. In the example, the method is applied to ECG recordings and a spectral analysis is thereby shown.

Algorithms↗

PubMed1988

Newer data on the configuration and variability ranges of body surface maps in a sample of normal subjects.

Quantitative data on the normal variability of body surface maps (BSM) are scarce in the literature. This is one of the reasons why BSM are not yet widely used in clinical practice despite their superior information contents. In this study we determined the average value and variability of a number of parameters derived from BSM in a group of 36 normal adult males, ages 22 to 60. Forty to 60 homogeneous beats were averaged for each subject. This enabled us to extend our study to the low voltage intervals (P,PQ,ST,U) which encompass more than 60% of the entire P-U duration and to contribute new data to controversial issues, such as the presence of two simultaneous maxima during atrial excitation. The following parameters were measured: a) the coordinates of the absolute potential maximum and minimum on the chest surface during the entire cardiac cycle; b) the time course of four voltage-related functions, namely: highest instantaneous potential value on the chest surface, lowest (most negative) potential, highest potential difference, and surface integral of the absolute value of the potential function. In recent studies these parameters were shown to be of considerable value in discriminating normal subjects from different categories of cardiac patients.

Adult↗