Factors influencing pricking pain threshold using a CO2 laser.

The purpose of this study was the evaluation of the best experimental conditions in healthy subjects for the measurement of the minimal thermal energy density E1 which induced pricking pain on the volar surface of the left forearm by means of CO2 laser pulses. E1 was measured on a well-defined area, using laser pulses of different durations and constant power P. The dependence of E1 on the stimulus power P, the size A of the radiated area and the surface temperature T(e) were explored. In the first part of the study, these relations were obtained using a computer program, from the calculated spatio-temporal distribution of the skin temperature during, and following, a laser pulse which caused pricking pain. The second part studied a set of subsequent measurements carried out on a group of five healthy trained subjects and agreed only in part with the calculated data. We found that the measurement error on E(t) was less than 10% with P between 1.5 and 3 W, and A between 0.15 and 0.25 cm2, respectively. The influence of sensitization and adaptation phenomena on the measured data was also explored. We also show a rhythmic annual change of T(e) and E1.

Numerical method for the interpolation of digitized lines (unrolling method).

The proposed method can be used for reconstructing, from n not necessarily equidistant points of a digitized polydrome line, a set of n1 equidistant points (with n1 > n) interpolating the original points. This method is based on a transformation of the original line into a digitized monodrome function D(1i) (unrolling function), where 1i is the line length between the origin and the ith point (i = 1,..., n1). Advantage of this method consists in reducing the two-dimensional interpolation problem to the one-dimensional field. In scintigraphic imaging, it is possible to achieve interpolation and coding of ROI's (Regions Of Interest) edges. For n samples of a monodrome line this method can also be applied, representing a possible alternative to splines. The numerical procedure is developed to reduce the noise on the points.

Pain threshold changes by skin vibratory stimulation in healthy subjects.

The purpose of this research is to evaluate the changes of cutaneous pain threshold induced by vibratory stimuli applied to the skin. The pain threshold was tested by means of electrical stimuli using the method of limits. Both vibratory stimuli (conditioning stimuli) and electrical stimuli (test stimuli) were driven by a computer. The experiments were carried out on the dorsal surface of the second phalanx of the index finger in the dominant hand of 34 healthy subjects (18 males and 16 females). The conditioning stimuli were sinusoidal waves (250 microm peak to peak) at a rate of 30 and 300 Hz. During the experiment (6 min of vibration and 9 min after) the cutaneous temperature of the stimulated area was recorded. Both vibratory rates induced significant increases of the pain threshold but the 30 Hz vibrations were the more effective. After stimulation the pain threshold lowered to a steady value which was higher than before the start of vibrations. Such threshold changes showed no correlation throughout the experiment with changes in skin temperature. We therefore advance the hypothesis that the main factors which modulate the pain threshold are neuronal connections between tactile and pain pathways.

Abnormalities of left ventricular shape in patients with stable angina.

In this study, left ventricular shape was evaluated quantitatively by calculating the power spectrum and the regional curvatures of angiographic outlines as seen in the right oblique anterior projection. Two groups of patients were studied: 16 normal subjects and 16 patients with stable angina who were selected because of normal left ventricular function (normal left ventricular volumes, pressures, ejection fraction and no regional wall motion abnormality at subjective analysis of ventriculograms). The two groups did not differ in terms of mean age of the patients. Regional curvatures were calculated using the Frenet-Serret formula starting from the mitral corner (point 1) and extending to the aortic corner (point 90). The power spectrum was calculated by means of Fourier analysis. The ventricular shape during diastole of the patients with angina differed significantly from that of the normal group in that there was a greater posterobasal curvature; a lower curvature of the inferior wall showing an inward convexity; a greater parietal curvature of the inferoapical region and a minor curvature of the anterobasal region. The power spectrum differed significantly from that of the normal subjects. The 1st and 2nd harmonics were reduced and the 3rd, 4th, 5th and 6th ones increased. The end-systolic contour of the group of patients with stable angina showed a higher amplitude of the 3rd and 5th harmonics and a lower amplitude of the 1st, 2nd, 9th, 10th and 11th harmonics with respect to the group of normal patients. Regional curvatures showed significant differences between the two groups in the antero-basal region. These modifications of left ventricular shape in patients with stable angina did not appear to be related to age and/or heart rate; to abnormalities in hemodynamics and wall motion; or to acute ischemia. Abnormalities of shape in patients with stable angina, therefore, may indicate a remodeling of the left ventricle due to the structural effects (myocardial and/or interstitial) of chronic ischemia.

[Analysis of the shape of the left ventricle by studying the regional curvature and power spectrum. I. Methodology and results in normal subjects]. / Analisi della forma del ventricolo sinistro mediante studio della curvatura regionale e dello spettro di potenza. I. Metodologia e risultati nei soggetti normali.

Quantitative analysis of left ventricular shape, obtained by measuring the regional curvatures and power spectrum of the harmonics of left ventricular outlines, is a useful method that has seldom been used in clinical research because of the need for a reliable and replicable method. The curvature of each point of an outline is the reciprocal of the radius of the circle that best fits a segment of the arc (window) centred at any specified point. We proposed a method based on the rate of change of the tangent vector with respect to the change in arc length, normalized for the width of the considered segment (Frenet-Serret formula). The series of curvature values allows us to obtain the power spectrum by means of Fourier analysis. The application of the method to a series of ellipses with variable eccentricity and size demonstrated that the width of the window is critical in the circulation of the curvature, and the choice of the number of points for computing has to be optimized to obtain the best signal-noise ratio. The method, applied using a sampling every 0.1 mm and optimized using a window of 25 points in the experimental model, is independent of the size of the samples, is able to distinguish small variations of eccentricity and to separate the signal from the noise due to digitizing and computing up to the 12th harmonic. The method has been applied to the left ventricular outlines of 16 subjects without any cardiac abnormalities.(ABSTRACT TRUNCATED AT 250 WORDS)

[Analysis of the shape of the left ventricle by studying the regional curvature and power spectrum. II. Morphologic changes in post-infarction ischemic heart disease]. / Analisi della forma del ventricolo sinistro mediante studio della curvatura regionale e dello spettro di potenza. II. Modificazioni morfologiche nella cardiopatia ischemica post-infartuale.

The quantitative analysis of left ventricular shape in ischaemic heart disease has seldom been performed because of the lack of a reliable and reproducible method of analysis. Diastolic and systolic left ventricular outlines in two groups of patients with previous myocardial infarction (anterior in 13 cases and inferior in 14 cases) were studied by analyzing the regional curvature and the power spectrum. This method allowed us to obtain left ventricular curvatures from the mitral to the aortic corner and the power spectrum of the first 12 harmonics. The results obtained in these two groups were compared with those obtained in 16 normal subjects. The diastolic power spectrum in both infarcted groups was similar. It was characterized by a double peak which was different from that of the normal subjects. Slight differences between the two infarcted groups were due to the diverse amplitude of the highest harmonics. The regional analysis of the curvature in both groups showed similar abnormalities of the posterobasal, inferior and antero-basal regions. The posterior wall showed a uniform curvature with the point of minimum shifted towards the mitral corner; the anterior wall showed a rounded profile with a regular curvature. In the group with anterior myocardial infarction the curvature of the inferior wall was negative, i.e., convex towards the left ventricular cavity. The systolic power spectrum showed a double peak profile which was different from that of the normal subjects. There were some differences between the two groups as regards the first and the highest degree harmonics. In inferior myocardial infarction the apex was rounded whereas in the anterior one the most important abnormalities were the convexity of the inferior wall towards the inside and the presence of a region with minor curvature between two regions with greater curvature of the anterior wall. Some of the systolic abnormalities involved the probable site of the infarct while others were in remote regions. The meaning of remote abnormalities is not clear. However, we did not verify a correlation between wall motion, at least as shortening of radii, and regional curvature. The abnormalities of the diastolic outline were independent of the site of the infarct and did not appear to be correlated to end-diastolic pressure or to the ejection fraction. They seemed to be the morphological counterpart of the filling abnormalities reported in ischaemic cardiac disease and they may depend on the regional distribution of stresses.

[Quantitative evaluation of isotopic left ventriculography]. / Valutazione quantitative della ventricolografia sinistra isotopica.

A radioisotopic technique which, through the injection of 99mTc-red cell into the pulmonary artery, gives images of left ventricular chamber in RAO at first pass and in LAO at blood pool gated, has been assessed. A quantitative analysis of left ventricular wall motion was performed with semiautomatic program. The Authors report their experience with 42 patients.

[Quantitative evaluation of left ventriculography with contrast media and radioisotopes]. / Valutazione quantitativa della ventricolografia sinistra contrastografica ed isotopica.

A radioisotopic technique which, through the injection of 99mTc-red cell into the pulmonary artery, gives images of left ventricular chamber in RAO at first pass and in LAO at blood pool gated, has been assessed. A quantitative analysis of left ventricular wall motion was performed with semiautomatic program. The Authors report their experience with 30 CHD patients.

[Left ventricular kinetics in bundle-branch block. Analysis by different methods in patients without coronary artery diseases (author's transl)]. / La cinetica ventricolare sinistra nel blocco di branca sinistra. Analisi con diversi sistemi di riferimento in pazienti non affetti da cardiopatia coronarica.

Radiological ventriculographic findings of twenty-three patients with left bundle branch block (LBBB) without valvular heart disease and without evident coronarographic lesions are studied by means of six differents methods for quantitative evaluation of wall motion analysis. The patients are subdivided into two subgroups on the basis of hemodynamic criteria, but the results of wall motion studies are similar in both, if the values obtained are normalized for election fraction (EF). End-diastolic images of left ventricle are similar in both subgroups too, but very different from those of normals because apical region is characterized by rounded contour of images. The modes of contractility in LBBB patients evidence, after normalization by the same EF, hypercinetic motility of anterior wall. The patterns of contractility, shaped by progressive simulated EF, show that low EF are obtained through contraction of anterior wall. Greater EF are obtained by further uniform contraction of all the explored regions. The apical zone in LBBB patients is affected by persistent hypokinesis.

[Left ventricular regional kinetics. Comparative analysis of the reference systems, correlations and physiological considerations]. / Cinetica regionale ventricolare sinistra. Analisi comparativa dei sistemi di riferimento, correlazioni e considerazioni fisiologiche.

The AA. studied segmental wall motion of the LV by means of 7 different methods. The study was performed in order to determine which reference system is the best for utilizing in subjects not affected by any heart disease. Two interesting points have emerged: first the methods which utilise the gravity center are the most sensitive; second, LV wall motion depends on the ejection fraction. In this perspective the AA. present a model of left ventricular motion.