β-adrenergic receptor blockade can also help reduce ventricular following rates in atrial flutter and fibrillation, again by acting at the AV node. (pharmacology2000.com)
I.V. administration is used for rapid beta-receptor blockade in treatment of atrial fibrillation with high ventricular following rates. (pharmacology2000.com)
E. The chronic or long standing PSVT'S like atrial flutter or fibrillation do not revert without treatment,often fail to revert even with attempted treatment and if reverted will often recur despite therapy. (rjmatthewsmd.com)
Radiofrequency catheter ablation techniques are safe and effective as well, especially for patients with poor tolerance to drugs (see figure figure 3b radiofrequency ablation in WPW, as well as in the treatment of atrial flutter and fibrillation by identifying tract carrying the excitation impulse). (rjmatthewsmd.com)
A large number of studies have found that in heart failure, atrial fibrillation, myocardial hypertrophy and myocardial infarction, atrial and ventricular HCN2 and HCN4 channels gene express unusually causing atrial or ventricular myocyte If current rise or fall, and all of these may be associated with heart disease fatal arrhythmia [18] . (bjcvs.org)
Ventricular fibrillation ( V-fib or VF ) is an abnormal heart rhythm in which the ventricles of the heart quiver instead of pumping normally. (mdwiki.org)
INTRODUCTION - Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia in clinical practice. (medilib.ir)
See "Atrial fibrillation: Overview and management of new-onset atrial fibrillation" . (medilib.ir)
EPIDEMIOLOGY - Atrial fibrillation (AF) is a global health care problem with evidence suggesting an increasing prevalence and incidence worldwide [ 4-6 ]. (medilib.ir)
Atrial ectopic tachycardia is believed to be secondary to increased automaticity of a nonsinus atrial focus or foci. (medscape.com)
This arrhythmia, which is also known as ectopic atrial tachycardia or automatic atrial tachycardia, has a high association with tachycardia-induced cardiomyopathy. (medscape.com)
Atrial ectopic tachycardia is often refractory to medical therapy and is not usually responsive to direct current (DC) cardioversion. (medscape.com)
The diagnosis of atrial ectopic tachycardia is based on the presence of a narrow complex tachycardia (in the absence of aberrancy or preexisting bundle branch block) with visible P waves at an inappropriately rapid rate. (medscape.com)
Patients with atrial ectopic tachycardia may present with circulatory collapse similar to patients with cardiomyopathy. (medscape.com)
Three options are available for long-term treatment of patients with atrial ectopic tachycardia: medication to suppress the arrhythmia or control the ventricular response, catheter ablation, or, uncommonly, surgery (see Treatment ). (medscape.com)
A small cluster of cells with abnormal automaticity is presumed to be responsible for atrial ectopic tachycardia. (medscape.com)
Because atrial ectopic tachycardia is often incessant, tachycardia-induced cardiomyopathy is commonly observed. (medscape.com)
Atrial tumors have been reported to be associated with atrial ectopic tachycardia. (medscape.com)
[ 2 ] Atrial ectopic tachycardia originating from aneurysms of the right atrial appendage has been reported. (medscape.com)
The adult form of atrial ectopic tachycardia may have a different etiology and natural history than the pediatric form. (medscape.com)
Although the exact incidence is unknown and few large series have been reported, atrial ectopic tachycardia reportedly comprises 5-10% of pediatric SVTs. (medscape.com)
Although estimates of the incidence of pediatric SVTs widely vary, atrial ectopic tachycardia likely occurs with an incidence of approximately 1 case per 10,000 children. (medscape.com)
Tachycardia-induced cardiomyopathy is the most significant sequela of atrial ectopic tachycardia and may be insidious. (medscape.com)
There are three main physiological explanations for premature ventricular contractions: enhanced ectopic nodal automaticity, re-entry signaling, and toxic/reperfusion triggered. (wikipedia.org)
Ectopic enhanced nodal automaticity suggests foci of sub-pulmonic valvular pacemaker cells that have a subthreshold potential for firing. (wikipedia.org)
Myocardial4
This condition is frequently seen in patients with underlying heart disease that creates areas of differential conduction and recovery due to myocardial scarring or ischemia. (wikipedia.org)
In a limited number of studies of patients with compromised myocardium (severe congestive heart failure, acute myocardial infarction, hypertrophic cardiomyopathy), administration of intravenous diltiazem produced no significant effect on contractility, left ventricular end diastolic pressure, or pulmonary capillary wedge pressure. (nih.gov)
The myocardial wire was implanted directly into the myocardium with the other end connected to an exterior stimulator. (wikidoc.org)
Reentry occurs when an area of 1-way block in the Purkinje fibers and a second area of slow conduction are present. (wikipedia.org)
G. There is a slow conduction pathway as well as a fast one. (rjmatthewsmd.com)
Supraventricular1
The therapeutic benefits of diltiazem in supraventricular tachycardias are related to its ability to slow AV nodal conduction time and prolong AV nodal refractoriness. (nih.gov)
Nodal refractoriness1
β-adrenergic receptor blockers increase AV conduction time and increase AV nodal refractoriness, thereby helping to terminate nodal reentrant arrhythmias. (pharmacology2000.com)
Arrhythmias2
During hypertension and heart failure, If activity is observed in the ventricular myocardium due to re-expression of HCN genes [18,21-23] , several studies proved that If current density and occurrence is significantly greater in hypertrophic cardiomyocytes and end-stage failing hearts and this is directly related to the arrhythmias [18,21,24-27] . (bjcvs.org)
Problems such as atrial arrhythmias are very common and quite benign, with little influence on the patient's hospital course or long‐term prognosis. (thoracickey.com)
Sinoatrial2
In the healthy adult heart, HCN channels are predominantly expressed in the conduction system, especially in the sinoatrial node, HCN4 has been determined as the principal HCN isoform in sinoatrial node cells. (bjcvs.org)
It has no effect on the sinus node recovery time or on the sinoatrial conduction time in patients without SA nodal dysfunction. (nih.gov)
Tachycardias2
Occasionally, mycoplasmal or viral infections, such as respiratory syncytial virus , may trigger this arrhythmia, although more complex atrial tachycardias, such as chaotic atrial tachycardia, are more frequently found in this scenario. (medscape.com)
Diltiazem exhibits frequency (use) dependent effects on AV nodal conduction such that it may selectively reduce the heart rate during tachycardias involving the AV node with little or no effect on normal AV nodal conduction at normal heart rates. (nih.gov)
Ventricle2
A conduction delay from atrium to ventricle often occurs, with most patients demonstrating first-degree AV block and some showing second-degree block. (medscape.com)
[18] demonstrated for the first time comparing the mRNA and protein expression of HCN subunits in the human atrial and ventricle under normal and heart failure conditions in human heart failure, an upregulation of ventricular HCN2 and HCN4 underlies the increase in functional If current, Michael et al. (bjcvs.org)
Ventricular rate1
the ventricular rate may be less when AV conduction is incomplete. (rjmatthewsmd.com)
Disturbance1
When there is a disturbance in the normal conduction through the fast pathway, the slow pathway may be activated to conduct the excitation wave to the bundle of His, as well as retrograde back to the fast one, and then back again down the slow pathway continuously to produce the PSVT (see Figure 1). (rjmatthewsmd.com)
Premature1
Simulations also demonstrated that β-adrenergic receptor stimulation in this specific region reduced the formation of conduction block and the probability of premature ventricular activation propagation. (frontiersin.org)
Sinus node1
Порушення функції синусового вузла Sinus node dysfunction refers to a number of conditions causing physiologically inappropriate atrial rates. (msdmanuals.com)
Pathways1
His-Purkinje tissue, atrial and ventricular muscle, and extranodal accessory pathways. (nih.gov)
The conduction spreads from this cluster to the surrounding atrium and to the ventricles via the atrioventricular (AV) node. (medscape.com)
Conduction time through AV node is increased while contractility is diminished. (pharmacology2000.com)
The SA node may be insulated from the surrounding atrial myocytes except at a limited number of preferential exit sites. (medilib.ir)
Pacemaker1
The primary purpose of a pacemaker is to maintain an adequate heart rate , either because the heart's native pacemaker is not fast enough, or there is a block in the heart's electrical conduction system . (wikidoc.org)
Currents1
While the calcium and potassium currents are the predominant determinants of SA nodal automaticity, there is evidence to suggest that the sodium channel may also play a role. (medilib.ir)
Tissue1
The damaged myocardium acts as substrate for re-entrant circuits, due to changes in tissue refractoriness. (medscape.com)
Electrical2
Evidence exhibits that HCN channels play critical roles in the generation and conduction of the electrical impulse and the physiopathological process of some cardiac diseases. (bjcvs.org)
Complications can be roughly categorized as Electrical dysfunction (conduction. (msdmanuals.com)
Dysfunction1
AMI is characterized by generalized autonomic dysfunction that results in enhanced automaticity of the myocardium and conduction system. (medscape.com)
Structural2
The chronic and recurrent ones are related to underlying structural causes like atrial disease or mitral disease. (rjmatthewsmd.com)
C. They tend to be recucurrent when an underlying structural cause such as atrial disease or mitral disease is the dominant pathophysiologic factor. (rjmatthewsmd.com)
System2
Under normal conditions, HCN channels are poorly expressed outside the cardiac pacemaking and conduction system [11,18-20] , but it changes during cardiac disease. (bjcvs.org)
Furthermore, transmural infarction can interrupt afferent and efferent limbs of the sympathetic nervous system that innervates myocardium distal to the area of infarction. (medscape.com)
Block2
While high levels of overall cardiac sympathetic drive are a negative prognostic indicator of mortality following MI and during heart failure, β-adrenergic receptor stimulation in the infarct border zone reduced spatially heterogeneous alternans, and prevented conduction block and propagation of extrasystoles. (frontiersin.org)
It was long after the concept of heart block from Chinese physician Pien Ch'io that the treatment was sought, due to the scarce knowledge of the details of the cardiac conduction. (wikidoc.org)
Longer1
Dual voltage/calcium optical mapping of post-MI Langendorff perfused hearts (using RH-237 and Rhod2) demonstrated that the border zone was significantly more prone to alternans than the surrounding myocardium at longer cycle lengths, predisposing to spatially heterogeneous alternans. (frontiersin.org)
Channels1
This is exacerbated by changes in the expression of membrane ion channels and under-expression and reorganization of gap junctions ( Luke and Saffitz, 1991 ) in the infarct border zone also slowing conduction ( Tse, 2016 ). (frontiersin.org)