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At least 73 records · Page 4Linked to original sources
PubMed1979

[Morphology of the heart conduction system].

Using his own experience and literary research, the author gives an outline of the morphology of the conduction systems of normal children's and adult hearts, including its blood supply.

Adolescent↗
PubMed1992

[Effect of epirubicin on the heart conduction system in patients with Hodgkin's disease].

24 patients (12 women and 12 men) aged 17 to 70 years with Hodgkin's disease in the clinical stages IIA-IVB were treated according to the polychemotherapeutic schemes containing epirubicin (epiDX). Using the 24-hour ambulatory ECC on the day before and the day of drug application as well as after completion of the therapy, heart rate, arrhythmias and conduction abnormalities were estimated. There was statistically insignificant decrease in heart rate (mean, minimal and maximal) on the day of epiDX administration and after therapy completion. Arrhythmias in form of supraventricular and ventricular extrasystoles including bigeminy and couplets of VES in one patient and two episodes of atrial tachycardia in another one on the day of drug injection were noticed. In 2 young women occurred interruption of sinus rhythm lasting longer than 3 sec., due to sinus arrest in one and due to 2:1 sinus exit block in the second one. The above mentioned disturbances were in majority of patients not associated with clinical symptoms. The authors conclude that the reduction in heart rate and SVES formation might be in the majority of patients neurogenic but in some of them as well as VES generation result from epiDX action.

Adolescent↗
PubMed1990

Neurofilament proteins are co-expressed with desmin in heart conduction system myocytes.

We have recently shown that specialized myocytes of the rabbit heart express a cytoskeletal protein similar to the M subunit of neurofilaments (NF). Since this result was obtained using a single anti-NF-M monoclonal antibody, we tested on conduction myocytes a panel of five anti-NF antibodies, specific for each of the three NF subunits and for phosphorylated and non-phosphorylated epitopes. Two antibodies, one specific for the L subunit and one for phosphorylated M subunit of NF, reacted with specialized myocytes in immunohistochemistry. In immunoblots on conduction tissue homogenates the two antibodies recognized two polypeptides with electrophoretic mobility and solubility properties identical to those of NF-L and NF-M in the sciatic nerve. The subcellular distribution of NF immunoreactivity in specialized myocytes was very similar to desmin localization; namely, it was distributed on large filamentous bundles and on fine filaments localized transversely at the level of the Z line. At the ultrastructural level, immunoreactive filaments were localized in the intermyofibrillar space and connected myofibrils with mitochondria. Co-expression of NF proteins and desmin was also observed in vitro in a minor population of cardiac myocytes cultured from embryonic rabbit heart. In most cases NF immunoreactivity co-localized with desmin, especially where filaments were well organized, but in some cells anti-NF and anti-desmin antibodies labelled different filamentous structures. These results indicate that NF proteins are structural components of the cytoskeleton of specialized myocytes and show a subcellular distribution very similar to desmin. Such a composition of intermediate filaments indicates that in these cardiac cells muscle differentiation is compatible with the expression of neuronal proteins.

Animals↗
PubMed1996

[Heart conduction system and accessory pathways].

The morphology of atrioventricular (AV) junctions in the heart has been investigated using comparative anatomical analyses. For scanning electron microscopy, tissue blocks are treated with HCl to digest connective tissue elements. In fishes, amphibians and reptiles, there is a muscular system connecting the atrial muscle to the ventricular myocardium. These muscle fibers completely surround the inner surface of the atrioventricular ring and termed "ring muscular tissue", the cells of which are slender and small and vertically oriented. They contain small-sized mitochondria, relatively few myofibrils and variable amounts of glycogen. In mammalian hearts, the AV node and bundle system is the only functional myocardial connection between the atria and ventricles. Architecture and ultrastructure of AV nodal cells are similar to those of AV ring muscular tissue seen in the lower vertebrates. In human hearts, however, the muscle bundles which directly connect the atrium with the ventricle, i.e., accessory conduction pathways, are scarcely encountered. From the developmental- and comparative-anatomical points of view, it is likely that the accessory pathways in man are the remnants of the ring muscular tissue seen in lower vertebrates.

Animals↗
PubMed1975

[Electrophysiological effects of the antiarrhythmia agents disopyramide and propafenone on human heart conduction system].

The effect of Disopyramide and Propafenone on intracardiac conduction and refractory periods was tested by means of His bundle electrography and atrial stimulation. Disopyramide (1,7 mg/kg) was administered in 10 patients. There was no significant change of heart rate and conduction time within the atrium and the AV-node. The conduction velocity within the His-Purkinje system was significantly slowed by 13% of the control value. The ERP of the atrium as well as the ERP and FRP of the AV node were prolonged. Propafenone (1,7 mg/kg) was tested in 18 patients. The heart rate was significantly slowed by 13% of the control value. The conduction velocity within all compartments of the heart was depressed uniformly. The all-over-all prolongation of the HBE-intervals was 15%. Furthermore the results are in favour of a prolongation of the ERP of the atrium and the ERP of the AV node. The results can only partially explain the antiarrhythmic effect of the drugs. However, the data are important for assessing the possible side effects during antiarrhythmic treatment especially in patients with disease of the conduction system.

Adult↗
PubMed1991

[Status of the heart conduction system in patients with epileptic seizures].

Diagnostic computed transesophageal pacing was used to examine 45 patients with epileptic seizures of different genesis. Clinically, they had no signs of cardiac rhythm disturbances. 28 patients with heart arrhythmias and 30 practically healthy subjects served as control groups. 64.44% of the patients with epileptic seizures manifested different types of the clinically existing pathology in the conduction system of the heart. Among the practically healthy subjects, the analogous disorders accounted for 10%; only single premature heart beats were recorded during the examination. 60.71% of the control group patients with heart arrhythmias subjected to ECG studies demonstrated alterations of the epileptic type. It is concluded that there is a close relationship between the epileptic process and pathology of the conduction system of the heart.

Adolescent↗
PubMed1992

[The capacity for reactive DNA synthesis of the myocytes in the heart conduction system in experimental and clinical myocardial pathology].

The DNA synthesis has been studied in the conductive system (CS) myocytes, compared to that in atrial and ventricular myocytes: 1) in the left ventricular myocardial infarction induced in two- and three-week-old and adult rats, 2) after isoproterenol injections to adult rats and mice, and 3) in the hypertrophied human heart. The extent of DNA synthesis reactivation was evaluated by the cumulative labeling indices in experiments with multiple 3HTdR injections to rats and mice. In the human cardiac myocyte nuclei, the DNA content was determined by the Feulgen-cytophotometry. The difference between the control and experimental mean values of the labeling indices for CS myocyte nuclei was statistically significant only for atrioventricular part of the CS in the infarcted hearts of adult rats. In the human heart CS the ability of myocytes to polyploidization varies from one cell type to another, the lowest being in nodal cells.

Adult↗
PubMed1988

Heart conduction system: a neural crest derivative?

Using the anti-neurofilament monoclonal antibody iC8 we report here that muscle fibers of the conduction system of the adult and developing rabbit heart express a cytoskeletal protein antigenically and electrophoretically similar to the middle subunit of neurofilaments (NF-M). In the 11-day embryo a number of cardiac muscle cells also express a neural crest surface marker recognized by the monoclonal antibody HNK-1. Both markers are found in many cells of the 3rd and 4th branchial arches, which are populated by cells of neural crest origin. In the 11-day embryo cells of the 4th branchial arch are in close proximity to and intermingled with the atrial myocardium: cells co-expressing sarcomeric myosin heavy chain with iC8 and HNK-1 immunoreactivity are seen at these sites. The findings suggest that conduction tissue cells of the rabbit heart originate from a population of neural crest-derived cells migrating from the branchial arches into the developing heart.

Animals↗