Antiarrhythmics Flashcards
What is an anti arrhythmic
Antiarrhythmic agents are a group of pharmaceuticals that are used to suppress abnormal rhythms of the heart (cardiac arrhythmias), such as atrial fibrillation, atrial flutter, ventricular tachycardia, and ventricular fibrillation.
What are the different classes
class I- sodium channel blockers Class II - beta blockers Class III- Potassium Channel Blockers Class IV- Calcium channel blockers Class V- Others (Digitalis, glycosides and adenosine)
What is arrhythmia
Cardiac arrhythmia, also known as cardiac dysrhythmia or irregular heartbeat, is a group of conditions in which the heartbeat is irregular, too fast, or too slow. A heartbeat that is too fast - above 100 beats per minute in adults - is called tachycardia and a heartbeat that is too slow - below 60 beats per minute - is called bradycardia.[1] Many arrhythmias have no symptoms. When symptoms are present these may include palpitations or feeling a pause between heartbeats. More seriously there may be lightheadedness, passing out, shortness of breath, or chest pain.[2] While most arrhythmias are not serious some predispose a person to complications such as stroke or heart failure.[1][3] Others may result in cardiac arrest.
What facilitates cardiac arrhythmia
hypokalemia, impaired conduction, velocity, impaired refractory period, ischemia, hypoxia, acidosis and alkalosis.
What are some of the causes of arrhythmia
Post MI scarring of the heart tissue, cariomypathy, CAD, HBP, Diabetes, Hyperthyroidism, smoking, alcohol and drug use.
What is accessory pathway
An accessory pathway is an additional electrical conduction pathway between two parts of the heart. It alters characteristics of the electrical conduction system of the heart, and so has the potential to affect the cardiac cycle.
What is wolf-parkinson-white syndrome
Wolff–Parkinson–White syndrome (WPW) is one of several disorders of the electrical system of the heart that are commonly referred to as pre-excitation syndromes.WPW is caused by the presence of an abnormal accessory electrical conduction pathway between the atria and the ventricles. Electrical signals traveling down this abnormal pathway (known as the bundle of Kent) may stimulate the ventricles to contract prematurely, resulting in a unique type of supraventricular tachycardia referred to as an atrioventricular reciprocating tachycardia.
What is class I drugs
The class I antiarrhythmic agents interfere with the sodium channel. Class I agents are grouped by what effect they have on the Na+ channel, and what effect they have on cardiac action potentials.Class I agents are called Membrane Stabilizing agents. The ‘stabilizing’ word is used to describe the decrease of excitogenicity of the plasma membrane which is brought about by these agents. (Also noteworthy is that a few class II agents like propranolol also have a membrane stabilizing effect.)Class I agents are divided into three groups (Ia, Ib and Ic) based upon their effect on the length of the action potential
What is class IA drugs
intermediate rate of association/dissociation with open or activate sodium channels. Blocks Fast Na+ channels. Preferred in open or activated state. Increased action patellate duration and effective refactor period.
What are examples of class IA drugs
(Quinidine, Disopyramide and Procainamide)
What is the main side effect of IA drug
Torsade de Pointes
What are class IB drugs
rapid rate of association/dissociation with inactivated sodium channels. Blocks fast Na channels. Blocks inactivated channels. increased threshold of excitation and less excitation of hypoxic heart. Decrease APD and ERP. Used to treat ventricular arrhythmia but shorting QT and duration of action potential.
What are examples of IB drugs
(Lidocaine (CNS toxicity), Phenytoin(CNS effects) and Mexiletine (CNS toxicity)
What are class IC drugs
slow rate of association/ dissociation with sodium channels this leads to prolonged action potential slowing of phase 0. Blocks fast Na channels. Blocks fast Na channel and no effect on ADP and ERP. no ANS effect.
What are examples of class IC drugs
(Flecainide and Propafenone)
