Chapter 23- Antidysrhythmic Drugs Flashcards
Action potential
Electrical activity consisting of a self-propagating series of polarizations and depolarizations that travel across the cell membrane of a nerve fibre during the transmission of a nerve impulse and across the cell membrane of a muscle cell during contraction or other activity of the cell.
Action potential duration (APD)
For a cell membrane, the interval beginning with baseline (resting) membrane potential followed by depolarization and ending with depolarization to baseline membrane potential.
Arrhythmia
Literally “ no rhythm,” meaning absence of a heartbeat rhythm (i.e. no heartbeat at all). More commonly used in clinical practice to refer to any variation from the normal rhythm of the heartbeat.
Cardiac Arrhythmia Suppression Trial (CAST)
The name of the major research study conducted by the National Heart, Lung, and Blood Institute to investigate the possibility of eliminating sudden cardiac death in patients with asymptomatic, non-life-threatening ectopy that has arisen after a myocardial infarction.
Depolarization
The movement of positive and negative ions on either side of a cell membrane across the membrane in a direction that tends to bring the net charge to zero.
Dysrhythmia
Any disturbance or abnormality in the rhythm of the heartbeat.
Effective refractory period (ERP)
The period after the firing of an impulse during which a cell may respond to a stimulus but the response will not be passed along or continued as another impulse.
Internal pathways (Bachmann’s bundle)
Special pathways in the atria that carry electrical impulses spontaneously generated by the sinoatrial node. These impulses cause the heart to beat.
Relative refractory period (RRP)
The time after generation of an action potential during which a nerve fibre will show a (reduced) response only to a strong stimulus.
Resting membrane potential (RMP)
The transmembrane voltage that exists when cell membranes of heart muscle (or other muscle or nerve cells) are at rest.
Sodium-potassium adenosine triphosphatase (ATPase)
A mechanism for transporting sodium and potassium ions across the cell membrane against an opposing concentration gradient.
Sudden cardiac death
Unexpected, fatal cardiac arrest.
Threshold potential (TP)
The critical state of electrical tension required for spontaneous depolarization of a cell membrane.
Vaughan Williams classification
The system most commonly used to classify antidysrhythmic drugs
Based on electrophysiological effect
Antidysrhythmics
Drugs used for the treatment and prevention of disturbances in cardiac rhythm
