[Effects of unilateral stellate ganglion block on the ST-T segment and QT interval in a group of subjects with normal cardiovascular systems].
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Biomedical subjects
Publications and source records attributed to L Padeletti.
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Shortened return cycles after premature atrial stimulation (PAS) are commonly referred to as sinoatrial entrance block and exit delay at the sinoatrial junction or sinus-node reentries. In the 2 reported cases PAS at critical coupling intervals was followed by shortened return cycles characterized by a changed high right electrogram (and surface P waves in 1 case) and a normal sequence of atrial activation with unaltered intraatrial conduction. These changes lasted for some beats and a concomitant shorter or longer atrial cycle length was observed. Electrophysiological events furnish indirect evidence of sinoatrial pacemaker shift as a cause of incomplete interpolation in man.
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.
A case of ventricular tachycardia induced by atrial pacing is described. The hypthesis is considered that the arrhythmia could be triggered by direct activation of the ventricles along the preferential conduction pathways of the atria.
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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.
The authors have studied the hemodynamic effects of sublingually administered nitroglycerin (NG). Obtained data indicate that the response to NG is time-dependent. A first phase, lasting about 2 minutes, is characterized by a reduction of total systemic resistance (TSR) and an increase of cardiac output (CO), without significant variations of left ventricular filling pressure (FP) and blood pressure (BP). A modest increase of heart rate (HR) is observed. The second phase is characterized by a reduced FP and later, after 5 minutes, of BP. Subsequently HR increases to a greater degree, CO decreases and TRS presents a variation toward control values.
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Sinus node function was evaluated in 18 patients with sinus bradycardia without complaints (Group I), in 16 patients with sinus bradycardia and/or sinoatrial block with complaints (subgroup IIa) and in 14 patients with the bradycardia-tachycardia syndrome (subgroup IIb). Mean values of corrected sinus node recovery time (CSRT), atrial effective refractory period (AERP) and atrial functional refractory period (AFRP) differentiated significatively asymptomatic subjects of group I from the two subgroups of patients with sinoatrial disease, but failed to differentiate each subgroup from the other one. There was no significative difference in mean sinoatrial conduction time (SACT) between group I and each of the two subgroups. Three patients of subgroup IIa and 1 patient of subgroup IIb had a false negative response after both overdrive and premature programmed atrial pacing. Spontaneous cycle length was directly correlated with the sinus node recovery time and the atrial refractoriness in group I, and with the only sinus node recovery time in subgroup IIb. No direct correlations were observed in subgroup IIa. This suggests a less disturbed sinus node automaticity in bradycardia-tachycardia syndrome.
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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.
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.
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