cardiac impulse
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Heart ◽  
2021 ◽  
pp. heartjnl-2021-320304
Author(s):  
Damián Sánchez-Quintana ◽  
Robert H Anderson ◽  
Justin T Tretter ◽  
José Angel Cabrera ◽  
Eduardo Back Sternick ◽  
...  

Knowledge of the anatomy of the ‘conduction tissues’ of the heart is a 20th century phenomenon. Although controversies still continue on the topic, most could have been avoided had greater attention been paid to the original descriptions. All cardiomyocytes, of course, have the capacity to conduct the cardiac impulse. The tissues specifically described as ‘conducting’ first generate the cardiac impulse, and then deliver it in such a fashion that the ventricles contract in orderly fashion. The tissues cannot readily be distinguished by gross inspection. Robust definitions for their recognition had been provided by the end of the first decade of the 20th century. These definitions retain their currency. The sinus node lies as a cigar-shaped structure subepicardially within the terminal groove. There is evidence that it is associated with a paranodal area that may have functional significance. Suggestions of dual nodes, however, are without histological confirmation. The atrioventricular node is located within the triangle of Koch, with significant inferior extensions occupying the atrial vestibules and with septal connections. The conduction axis penetrates the insulating plane of the atrioventricular junctions to continue as the ventricular pathways. Remnants of a ring of cardiomyocytes observed during development are also to be found within the atrial vestibules, particularly a prominent retroaortic remnant, although that their role has still to be determined. Application of the initial criteria for nodes and tracts shows that there are no special ‘conducting tissues’ in the pulmonary venous sleeves that might underscore the abnormal rhythm of atrial fibrillation.


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Junichi Sugita ◽  
Katsuhito Fujiu ◽  
Yukiteru Nakayama ◽  
Takumi Matsubara ◽  
Jun Matsuda ◽  
...  

AbstractCardiac arrhythmias are a primary contributor to sudden cardiac death, a major unmet medical need. Because right ventricular (RV) dysfunction increases the risk for sudden cardiac death, we examined responses to RV stress in mice. Among immune cells accumulated in the RV after pressure overload-induced by pulmonary artery banding, interfering with macrophages caused sudden death from severe arrhythmias. We show that cardiac macrophages crucially maintain cardiac impulse conduction by facilitating myocardial intercellular communication through gap junctions. Amphiregulin (AREG) produced by cardiac macrophages is a key mediator that controls connexin 43 phosphorylation and translocation in cardiomyocytes. Deletion of Areg from macrophages led to disorganization of gap junctions and, in turn, lethal arrhythmias during acute stresses, including RV pressure overload and β-adrenergic receptor stimulation. These results suggest that AREG from cardiac resident macrophages is a critical regulator of cardiac impulse conduction and may be a useful therapeutic target for the prevention of sudden death.


2020 ◽  
Vol 11 ◽  
Author(s):  
Stefano Andrea De Simone ◽  
Sarah Moyle ◽  
Andrea Buccarello ◽  
Christian Dellenbach ◽  
Jan Pavel Kucera ◽  
...  

2019 ◽  
Vol 12 (3) ◽  
pp. e225411
Author(s):  
Ambreen Gul ◽  
Muhammad Asad Sheikh ◽  
Atif Rao

Runaway pacemaker is phenomenon in which pacemaker induces ventricular tachycardia as a result of some malfunction in the device. This entity is not very common in clinical practice. Normally, the pacemaker perceives the inherent cardiac impulse and hence averting the delivery of pacemaker stimulus in susceptible period of cardiac cycle. This is a case of a pacemaker-induced tachycardia (named as runaway pacemaker) in a patient with a history of Single Chamber Ventricular (VVI) pacemaker. A 75-year-old man was admitted with 3 days history of fluttering in the chest, shortness of breath, central chest and epigastric pain which radiated to the back. His medical history includes pacemaker implantation in 1996 with lead complication following which he was managed with VVI pacemaker, and the last procedure was generator change 4 years ago with no complication. Examination revealed ventricular tachycardia with ECG showing paced rhythm with ventricular pacing at the rate of 200–150/min. His pacemaker-induced ventricular tachycardia was immediately aborted after putting magnet on the device which restored his baseline rhythm with heart rate of 60/min. Pacemaker was explanted urgently with replacement of new pulse generator. The patient was discharged home with VVI pacemaker showing excellent parameters.


Author(s):  
Donatus Onukwufor Onwuli ◽  
Sandra A. Jones

Cardiac arrhythmia affects ~ 6% in those over 65 years of age (old), but with 0.2% occurrence in those of 45 years and below (young). Arrhythmia can result from dysregulation of the cardiac impulse generation and its conduction. Connexin proteins are responsible for cardiac impulse conduction, and phosphorylation of connexin 43 determines its functional ability. In this study, Phosphorylated connexin 43, density and expression were assessed in ventricular tissues from young (6 months old) and old (24 months old) Wister rats, using the techniques of western blot and immunohistochemistry. Results show that phosphorylated Cx43 in the left ventricle of 24 months old rats significantly declined (P=0.04 & 0.01) by method of western blot and immunohistochemistry respectively, but did not differ in the right ventricle. The left ventricle is known to be responsible for cardiac output. This data suggest an age-associated decline in the expression of phosphorylated connexin 43 in the left ventricle, which may play a significant role in the development of cardiac arrhythmia in the elderly.


2017 ◽  
Vol 38 (suppl_1) ◽  
Author(s):  
J. Sugita ◽  
K. Fujiu ◽  
Y. Nakayama ◽  
T. Matsubara ◽  
J. Matsuda ◽  
...  

Author(s):  
M. B Shvyrkov

With gunshot wounds person observed serious violations of the cardiovascular system. In 83,3% of the wounded was detected: deafness heart sounds, blood pressure instability with a tendency to hypotension, lability of heart rate, tachycardia, heart rhythm disturbances caused by changes in automaticity sino-atrial node, excitability and conduction of cardiac impulse, myocardial hypoxia, metabolic disorders. In wounds of the upper jaw to the EEG revealed a violation of brain biocurrents as gipersinhronizatsii and distribution of basic rhythm, dysrhythmia and reduced reactivity to afferent stimuli, hemispheric asymmetry.


2017 ◽  
Vol 2 (2) ◽  
pp. 68-70
Author(s):  
Naina P Dalvi ◽  
Apeksha A Gala ◽  
Sunil K Gvalani ◽  
Sourav Mahajan

ABSTRACT Sick sinus syndrome (SSS) is a generalized abnormality of cardiac impulse formation. Abnormalities encompassed by this syndrome may include inappropriate sinus bradycardia, sinus arrest, bradyarrhythmias, or tachyarrhythmias. We present a case of a 54-year-old hypertensive male posted for L4–L5 decompression, whom we suspected to develop SSS due to overdose of combined beta-blocker (BB) and calcium channel blocker (CCB) therapy. How to cite this article Gala AA, Dalvi NP, Gvalani SK, Mahajan S. A Case of suspected Sick Sinus Syndrome due to combined Beta-blocker and Calcium Channel Blocker Therapy: Anesthesia Management. Res Inno in Anesth 2017;2(2):68-70.


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