Arrythmias

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Dear Bloggers, In present blog, We will discuss briefly on some importance & basic matter on arrythmias. So, let we see : Definition : An arrhythmia is any abnormality in the rate, regularity, or site of origin or a disturbance in conduction that disrupts the normal sequence of activation in the atria or ventricles. [1] Reasons : electrolyte abnormalities structural abnormalities metabolic derangements genetic mutations drug toxicity [2] Types : Supraventricular Tachycardia Wolff-Parkinson-White (WPW) Syndrome. Atrial Fibrillation. Ventricular Tachycardia (VT). Bradycardia. Sick Sinus Syndrome A-V block or heart block. Sinus node dysfunction [3]. Arrhythmogenesis : In general, arrhythmia mechanisms have been described as abnormalities in electrical development, electrical conduction, or a combination of both. Abnormalities in electrical development arise from irregular automaticity or triggered activity from the SA node or other sites producing ectopic beats. Reentry and conduction block are the most common electrical conduction abnormalities associated with arrhythmogenesis. Reentry describes a concept of infinite impulse propagation by continued activation of previously refractory tissue. Reentry depends on different conduction velocities along adjacent myocardial fibers, with one fiber containing an area of unidirectional conduction block. This allows continued excitation in a repetitive manner. This circus rhythm may develop as areas of infarcted tissue block or delayed conduction. A single circuit of the fibers may induce a premature contraction, whereas continuous cycling of impulses might produce sustained tachycardia. This process may occur in both atrial and ventricular tissue. Conduction block occurs when the normal conduction pathway is blocked and the impulse either expires or conducts through an alternative inappropriate route to depolarize the myocardium. [4] Some common Antiarrhythmic Drugs by Vaughn-Williams Classification : Class 1a Quinidine Procainamidea Disopyramide Moricizineb Class 1b Lidocaine Tocainide Phenytoin Mexiletine Class 1c Flecainide Propafenone Class 2 v-blockers Class 3 Bretylium Amiodaroned Sotalole Ibutilide N-acetylprocainamide Class 4 Calcium channel blockers [5] REFERENCES : [1]http://www.clevelandclinicmeded.com/medicalpubs/diseasemanagement/ cardiology/cardiac-arrhythmias/ [2] http://heart-disease.health-cares.net/cardiac-arrhythmia- causes.php [3] http://heart-disease.health-cares.net/cardiac-arrhythmia- types.php [4] Roles of Sodium-Calcium Exchange, Inward Rectifier Potassium Current, and Residual ss-Adrenergic Responsiveness. Steven M. Pogwizd1, Klaus Schlotthauer1, Li Li, Weilong Yuan, Donald M. Bers . Circulation Research.2001;88:1159-1167 Published online before print May 24, 2001, doi:10.1161/hh1101.091193 [5] http://www.doctorslounge.com/cardiology/drugs/antiarrhythmic/
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Swagat K. Soni's picture
Author: Swagat K. Soni

Comments

K Rajakrishna's picture

Sir, you have very well explained the topic in short. Can your please explain about metabolic derangements. And drug toxicity. How do they cause arrhythmia
Amol Dhiaman's picture

Will you please tell me what happens in WPW syndrome. With Regards Amol Dhiman Team GLORY

Amol Dhiaman

Sirisha Pingali's picture

hello swagat One simple question but i dont have an appropriate answer.."Why do doctors check the patient with a stethoscope before treating. What kind of inference they can draw? Does this give a vague idea regarding arrhthymia?"

Sirisha Pingali

http://www.pharmainfo.net/sirisha

Viswanadha Institute of Pharmaceutical Sciences.

www.vnips.edu.in

Siva Mavuduru's picture

Its so easy to understand sir. I have one doubt. how metabolic derangements and drug toxicity causes arrhythmia?
SS Md Shafi's picture

nice blog....

may I know how arrhythmias conformed & how phenytoin acts....??

shafi ..

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