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Biomedical subjects

L Padeletti

Publications and source records attributed to L Padeletti.

At least 19 recordsLinked to original sources
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

Hemodynamic effects of nitroglycerin.

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.

Female↗
PubMed1979

Assessment of sinus node function in asymptomatic subjects with sinus bradycardia and in symptomatic patients with sino-atrial disease.

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.

Arrhythmia, Sinus↗
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↗
PubMed1979

The cardiac electrophysiological effects of nifedipine.

A study was carried out on the electrophysiological effects of a sublingually administered antianginal drug: nifedipine (20 mg). The results show a significant shortening of sinus cycle length from 925 +/- 249 msec to 810 +/- 245 msec, (p less than 0.005) and the disappearance of some interpolation and echo zones. There are no significant effects on the other evaluated parameters of sino-atrial and AV-node function. In one case, during atrial pacing, a second-degree, Wenckebach type, A-V block was present only before nifedipine. The following conclusions were reached: 1. nifedipine has no significant electrophysiological effect on the human heart; 2. the electrophysiological effects observed are probably indirect and related to the vasodilating effect of the drug; 3. the absence of direct cardiac electrophysiological actions may be useful in patients suffering from coronary artery disease and presenting disturbances in the formation and/or conduction of the cardiac impulse.

Adult↗
PubMed1978

[Dynamic geometry of the left ventricle. Relaxation and elasticity indices].

A study was made of 34 patients with valve defects or arterial hypertension and a haemodynamic picture of left ventricle pressure or volume load. Echocardiography and haemodynamic investigated-established the size and mass of the left ventricle and also enabled its indices of contractility, relaxation and distensibility to be determined. The series was divided in accordance with the dynamic geometry of the left ventricle. In concentric hypertrophy, telediastolic rigidity increased in proportion to ventricular thickness and mass. In eccentric forms and ventricular dilatation, diastolic distensibility was reduced in cases with a high filling pressure. The relaxation values bore no relationship to distensibility and telediastolic compliance. The relaxation rate in protodiastole diminishes in proportion to functional depression of the left ventricle.

Cardiac Catheterization↗
PubMed1978

Preliminary experience with the pH-triggered pacemaker.

A cardiac pacemaker capable of responding to blood acidosis by change in its stimulation rate allows adjustment to a patient's metabolic needs. The blood pH is sensed by an iridium oxide electrode in the right atrium. During exercise, the venous pH decreases and the paced ventricular rate increases. If acidosis persists, the paced rate gradually returns to baseline and reaches it after about 70 minutes. A pH-triggered pacemaker has been implanted in a 72-year-old male. The pacemaker remained responsive one year after implant, increasing rate during exercise, cold pressor stress, ischemia of the arms and emotional stress.

Aged↗
PubMed1978

[Clinical and biological aspects in patient with pH-triggered implanted pacemaker (author's transl)].

The Authors have selected the variations of blood pH to drive the pacing rate according to the new biological balance created by exercise. The clinical tests performed on the patients who have had a pH-triggered pacemaker implanted one year previously demonstrated that: a) during physical exercise there is an increase of cardiac rate triggered by the pacemaker, comparable with that noted when sinus rhythm is present; b) situations causing an increased production of cathecolamines and thus a pH variation--Cold Pressor Test, Ischaemic Test, as well as emotional stress--cause an increase of the stimulation rate of pH triggered pacemaker.

Blood↗
PubMed1978

Bioavailability of digoxin in capsules.

The authors have studied the bioavailability of a commercially available digoxin solution in capsule. Data obtained were different from that reported by other authors using experimental preparations. Single-dose and steady-state studies evidenced a similar bioavailability for capsules and standard tablets. These results introduce the new problem of the inadequate bioavailability of capsules.

Adult↗
PubMed1977

Digoxin and congestive heart failure.

The purpose of our study was to evaluate the absorption of digoxin in alcoholic solution in normal subjects and in patients on congestive heart failure whose water and electrolyte balances were determined. While the parameters of the distribution kinetics were not significantly different between the two groups, the areas under the serum concentration curve resulted increased in the patients on congestive heart failure indicating a more efficient absorption respect to the normal subjects.

Aged↗