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Biomedical subjects

M C Porciani

Publications and source records attributed to M C Porciani.

At least 19 recordsLinked to original sources
PubMed1995

Wavelength index at three atrial sites in patients with paroxysmal atrial fibrillation.

The purpose of this study was to evaluate the wavelength index (WLI) at three atrial sites in a group of 23 patients with recurrent episodes of lone paroxysmal atrial fibrillation (LPAF) and a control group (n = 20). All patients underwent programmed atrial stimulation (paced cycle length = 600 ms) at high, medium, and low lateral right atrial wall. P wave duration, sinus cycle length, and corrected sinus node recovery time were not significantly different between the two study groups. WLI was calculated according to the following formulas: atrial effective refractory period (AERP)/duration of atrial extrastimulus electrogram (A2) or AERP/A2 + atrial latency; and atrial functional refractory period (AFRP)/A2. WLI was significantly shorter in LPAF than in the control group at each of the paced atrial sites independently of the formula used. Duration of premature atrial electrogram appeared to play the major role in determining the difference in WLI between patients with paroxysmal atrial fibrillation and the control group.

Atrial Fibrillation↗
PubMed1988

Atrial electrophysiologic properties of patients with asymptomatic Wolff-Parkinson-White syndrome.

To evaluate the existence of a peculiar atrial electrophysiologic substrate, we studied 18 patients with asymptomatic Wolff-Parkinson-White (WPW) syndrome. These patients were compared with 10 age-matched normal subjects (N). Effective and functional refractory periods were determined at two right atrial sites (high and low in the lateral wall), during atrial pacing (100 min-1) and at twice diastolic threshold. Disperson (D) of effective (ERP) and functional (FRP) refractoriness was evaluated as the difference between refractory periods at the two atrial sites. WPW patients showed significantly lower mean values of effective and functional refractoriness at both atrial sites and significantly higher mean values of D-ERP and D-FRP. Moreover, in calculating the highest normal values of D-ERP and D-FRP (as mean values of N plus 2SD) it was observed that WPW with abnormal values of D showed a statistically (chi 2 test) higher incidence (100%) of induced atrial fibrillation (AF). These findings indicate the existence of both an abnormal atrial electrophysiologic substrate and of a higher vulnerability in WPW. Finally, AF was induced generally at the site with the lower refractoriness (i.e. low lateral site). This should be taken into account when considering how atrial fibrillation can be induced more easily.

Adolescent↗
PubMed1985

Effects of isoproterenol and methoxamine on the electrocardiogram.

The effects of isoproterenal (ISP) and methoxamine (MTX) infusion in 20 asymptomatic subjects with labile T wave were studied. In those treated with ISP the T wave showed an early negative trend and later became clearly positive in 5 subjects. In the majority of the subjects treated with MTX the T wave became positive. T wave changes match variations of both the ventricular gradient and, to a lesser degree, the QRS area. These changes were not related to heart rate or, in the subjects treated with MTX, to the baroreceptorial sensitivity deduced from the slope of the regression equation between R-R internal and systolic arterial pressure. The results of this study confirm the existence of a neurogenic mechanism affecting the electrocardiographic changes in T wave.

Adult↗
PubMed1984

Coexistence of pupillary and heart sympathergic asymmetries in cluster headache.

Ten cluster headache patients and 10 healthy controls were subjected to electrocardiographic and pupillometric procedures in a search for cardiac and pupillary sympathergic asymmetry. Sympathergic stimulation was provoked by hyperventilation and by instilling tyramine into both eyes. In the control group, hyperventilation changed neither the T-wave form and polarity nor the QTc. Tyramine provoked an equal mydriasis on the two sides. In cluster headache sufferers, hyperventilation produced changes in the T-wave form and polarity as well as an increase of the QTc due to a disproportionate shortening of the R-R and Q-T intervals. An unequal mydriasis was noted after tyramine instillation due to less marked response on the symptomatic side. The observed electrocardiographic abnormalities are considered an expression of an asynchronous repolarization attributed to a sympathergic asymmetry. It is postulated that both the cardiac and pupillary sympathetic imbalance associated with cluster headache are central in origin.

Adolescent↗
PubMed1982

Possible lateralization of the cardiac sympathetic function in cluster headache.

In cluster headache an adrenergic dysfunction of the pupillary sympathetic system can be demonstrated even during pain-free periods by instillation of tyramine in the conjunctival sac. In this study 10 patients with typical cluster headache syndrome exhibited a positive tyramine conjunctival test (minor mydriatic response in the pain side). As the adrenergic dysfunction may also involve the heart, possible neurogenic changes in ventricular repolarization were investigated in a group of patients with cluster headache by means of a hyperventilation test. When compared to controls, an increase of the QTc interval, a faster heart rate and a minor shortening of the QT interval, were observed. In all cases except one the T waves became bifid or inverted, sometimes showing a pseudoischemic aspect. Since the positive response to hyperventilation seems to depend on an asynchronous repolarization which can, in turn, be related to asymmetric sympathetic function, the present results seem to suggest the presence of a possible lateralization of the cardiac sympathetic function, in cluster headache patients.

Adolescent↗
PubMed1982

Pheochromocytoma presenting as possible cardiomyopathy.

A case of pheochromocytoma presenting as a possible hypertrophic obstructive cardiomyopathy is reported. In a 67 years old woman without previous history of hypertension, the echocardiogram showed left ventricular concentric hypertrophy and systolic anterior movement of the mitral valve. The carotid pulse was deformed with a spike-and-dome pattern. The complex interactions between myocardial adrenergic receptors sites and catecholamines, and the relation between these substances and the pattern of cardiac hypertrophy are discussed.

Adrenal Gland Neoplasms↗
PubMed1980

[Carcinoid heart disease. Report of a case (author's transl)].

A case of carcinoid tumor characterized by isolated tricuspid insufficiency with stenosis is reported. This valvular disease was characterized by a slight increase of cardiac output and pulmonary pressures. Necropsy did not evidence the site of the primitive tumor. Tricuspid valve lumen was near normal while the pulmonary valve presented slight stenosis. The correlations between clinical feature and necroscopic findings are discussed.

Autopsy↗
PubMed1979

Effect of isoproterenol on the "early repolarization" syndrome.

A study has been carried out on a group of subjects with RS-T segment elevation, a normal variant of early repolarization. Following isoproterenol administration, the RS-T segment became isoelectric. In most cases this was accompanied by shorter QT and longer QTc intervals. The same effects were observed after physical exertion but not after atropine or amyl-nitrite. Propranolol administration exaggerated RS-T elevation. Considering the mechanism with which isoproterenol acts and some analogies with the electrocardiographic picture experimentally obtained by means of the unilateral stimulation of the stellate ganglions, the hypothesis is advanced that the normal variant of early repolarization is related to an enhanced activity of the right sympathetic nerves.

Adult↗
PubMed1979

Placental transfer of digoxin (beta-methyl-digoxin) in man.

The dynamics of placental transfer of digoxin (beta-methyl-digoxin) has been studied in 20 pregnant women. The drug was administered in a single dose, intravenously, during labor. The samples drawn within the first hour after administration showed significantly lower fetal serum digoxin concentrations (SDC) than in the mother. No significant difference appeared in specimens collected after the first hour.

Amniotic Fluid↗
PubMed1979

Digoxin clearance and glomerular filtration rate.

The authors have studied the correlation between digoxin clearance and glomerular filtration rate. This correlation was better than between digoxin clearance and creatinine clearance without reducing the error of a programed therapy.

Aged↗