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Biomedical subjects

L Padeletti

Publications and source records attributed to L Padeletti.

At least 91 records · Page 5Linked to original sources
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↗
PubMed1977

[Effects of oxyfedrine on sino-atrial function and on conduction in patients with sinus node and/or atrial dysrhythmias (author's transl)].

The electrophysiological effects of Oxyfedrine on sino-atrial function and on A-V junctional and subjunctional conduction have been studied in 16 patients with sinus node and/or atrial dysrhythmias. The following effects have been observed: --a positive chronotropic effect on the sinus node; --an essentially indirect (rate-dependent) shortening of the Functional and Effective Refractory Periods (FRP and ERP) of the atria without variation of the Intra-Atrial Conduction Time (HRA-LRA). There was no significant shortening of the Maximal Atrial Latency (max AL), of the Corrected Sinus Node Recovery Time (CSNRT) and of the Sino-Atrial Conduction Time (SACT). The limits of Zones I, II, III of the sinus node response to atrial extra-stimuli were reduced with no significant change in their duration, expressed as percentage of the Sinus Cycle Length (SCL); --an improvement in the A-V junctional conduction (shortening of the A-H interval for comparable cycle lengths) due to a relatively shortened A-V junctional ERP. The use of the drug in patients with sinus bradycardia and/or atrial dysrhythmias and conduction disturbances, is proposed.

Adult↗
PubMed1976

Idioventricular parasystolic rhythms.

A description is given of the electrocardiograms of three subjects with artificial demand pacemakers in whom no inhibition of the idioventricular rhythms occurs, thus causing unusual relationships between the artificial and the spontaneous rhythms. The latter are protected and therefore appear to be parasystolic. In the first two cases, interpolated artificial beats are inscribed in the spontaneous rhythm. In the third case, the spontaneous parasystole is intermittent and alternates with concealed extrasystolic beats originating in the same focus.

Aged↗
PubMed1976

Bioavailability of digoxin and beta-methyl-digoxin.

In a randomized crossover study the bioavailability of a single dose of digoxin and of beta-methyl-digoxin tablets was tested in four normal volunteers. No difference was found between the two products in the rate and extent of drug absorption using 6 day cumulative urinary excretion and serial serum concentration measurements.

Adult↗