PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Heart Conduction System”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 235 records · Page 13Linked to original sources
PubMed1988

[Effect of allapinin on the function of the atrioventricular conduction system of the heart].

The effect of allapinin on atrioventricular conductivity was assessed at intracardiac electrophysiologic investigation in 11 patients with various heart rhythm disorders. The effect of a 30 mg intravenous dose of the drug was evaluated 60 min after the injection. Allapinin significantly lengthened the P-Q interval and expanded the QRS complex. The effect was associated with a 24% increment in the P-A interval, a 7% increment in the A-H interval and a 31% increment in the H-V interval, suggesting that allapinin can be regarded as belonging to the first class of antiarrhythmic agents by Vaughan Williams' classification. Allapinin also shortened effective refractory time of the atrium and the atrioventricular node, as well as the total refractory period of the His-Purkinje system. Ventricular refractory periods were also shortened insignificantly. The drug is therefore assumed to have a vagolytic or, perhaps, sympathomimetic action.

Aconitine↗
PubMed1981

[A new method of recording spike potentials of the atria from the body surface].

A new method of recording spike potentials (rapid deflections) of the heart conductive system (sinus node, atrial conductive tracts, His' bundle)from the body surface was developed using differential magnifying 50 to 250 times and yielding frequencies 30-110 Hz with special filters. The curves with differentially amplified spike potentials (DASP) of the heart conductive system were recorded in 249 patients with various cardiac arrhythmias; the control group consisted of 60 healthy persons. By means of synchronous recording of intracardiac ECG and DASP curves on the latter well recognizable points for the determination of the excitation spreading rate in certain areas of the conductive system were distinguished. The recording of DASP-curves allowed the determination of intraatrial conduction disturbances, atrial overloading and distinguishing of retrograde conduction in atria, sinoventricular conduction, ectopic prefibrillatory activity and differentiation of paroxysmal tachycardias. The new method of recording of spike potentials of the atria from the body surface allows the diagnosis of the conduction disturbances and cardiac arrhythmias, including life threatening ones, which were previously determined using exclusively intracardiac ECG. The application of our method enables to increase the possibilities of the investigation of cardiac arrhythmias and conductive disturbances and allows a multiple examination and evaluation of the influence of drugs on the heart conductive system.

Arrhythmias, Cardiac↗
PubMedDate not supplied

Pathology of the heart and conduction system in a case of sudden death due to a cardiac fibroma in a 6-month-old child.

A 6-month-old female infant considered to be in good health died suddenly and unexpectedly. Post-mortem examination was requested, with clinical diagnosis of sudden infant death syndrome. Gross examination revealed, however, the presence of a cardiac mass 4.5 X 4 x 3.5 cm in diameter. Histological examination of the heart confirmed the presence of a cardiac fibroma. In the present case, the sudden death could have been due to the left ventricular outflow obstruction, as much as to conductive disturbances caused by overstretching and compression of the atrioventricular node and of the bundle branches. Hemodynamic and conductive abnormalities are presumed to have provoked bradycardia degenerating into ventricular fibrillation and sudden death. Necroscopy studies of sudden death should always include histological examination of the cardiac conduction system but seldom do.

Female↗
PubMed1998

A PRC based model of a pacemaker cell: effect of vagal activity and investigation of the respiratory sinus arrhythmia.

In this study we present a computer model of a pacemaker cell subjected to vagal stimulation. This model allows us to investigate the entrainment phenomena of the pacemaker cell resulting from its dynamic interaction with a periodic train of vagal bursts. The possibility of entrainment depends mainly on the fact that a vagal stimulation discharge can "correct" the pacemaker rhythm by an amount that depends on its instantaneous relationship to the pacemaker cycle length. This very simple model, is based on the two most important functional properties of the cardiac pacemaker cells. The first property is the intrinsic pacemaker cycle length, which is an "internal" parameter of the cell, describing the most basic feature of a pacemaker cell. The second one is the phase response curve (PRC), which is an "overall collective" function, containing all the "information" about the possible interactions between the pacemaker cell and the outside world (i.e. its interaction with surrounding cells, external stimulus, etc.). A "collective" PRC was reconstructed from the resulting effects of all the pulses composing a burst. It appears that the PRC parameters as well as the vagal burst parameters are important factors in predicting the entrainment phenomena. Specifically, we found that the tendency of the pacemaker cell to become synchronized with bursts of vagal activity is greater, the larger the number of pulses per burst. However, increasing the number of pulses may also increase the tendency of the pacemaker towards instability, which was unveiled as changes in the configuration of the "collective" PRC. We applied the periodic train of vagal bursts so as to simulate the respiratory sinus arrhythmia (RSA) modulation on the pacemaker cell. We included also a modulation of sympathetic origin, represented as periodic changes in the intrinsic pacemaker cycle length. The frequency response of the pacemaker to "autonomic" modulations allowed us to demonstrate that the RSA dynamics can be interpreted in terms of the entrainment of the pacemaker cell by the respiratory modulation of vagal activity.

Autonomic Nervous System↗