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digitalis (dĭjˌĭtălˈĭs), any of several chemically similar drugs used primarily to increase the force and rate of heart contractions, especially in damaged heart muscle. The effects of the drug were known as early as 1500 B.C.; it was later obtained from the foxglove plant, Digitalis purpurea, and from fuchsia (see figwort). It was used in the 19th cent. to treat dropsy (edema). Digitalislike substances are found in a wide variety of plants and animals, including the poisons of some toad species. Foxglove remains the main source for the drug used medically today.

Chemically, digitalis is composed of a sugar (glycoside), a steroid, and a cyclic ester known as a lactone; the pharmacological activity varies according to differences, occurring naturally or introduced synthetically, in the steroid or sugar portions. Common preparations include digitalis, digitoxin, and digoxin, all from foxglove, and ouabain from Strophanthus gratus, the ouabaio tree; these vary both in solubility and in rapidity and duration of effect.

Digitalis slows the pulse and slows the conduction of nerve impulses in the heart. By increasing the amount of calcium available to the heart muscle, it improves the force of each heartbeat and increases the amount of blood pumped. It is used in the treatment of congestive heart failure and cardiac arrhythmias. The mechanism by which it acts to enhance heart muscle contraction is not definitely known. Toxic effects include nausea, vomiting, and visual disturbances.

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(organic chemistry)
C41H64O14 A crystalline steroid obtained from a foxglove leaf (Digitalis lanata); similar to digitalis in pharmacological effects.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
The results from a 10-year randomized trial known as the CABANA trial (Catheter Ablation versus Antiarrhythmic Drug trial for Atrial Fibrillation) have recently been released.
No cardiac injury was determined, and the rhythm reverted to normal sinus rhythm spontaneously on the 3rd hour after the accident without the use of any antiarrhythmic drug.
Findings during electrophysiology testing Finding Atrial flutter Sinus rhythm P value group (n = 94) group (n = 94) Spontaneous atrial 2 (2.1%) 4 (4.3%) 0.68 fibrillation Inducible atrial 7 (7.5%) 20 (21.3%) 0.007 fibrillation Atrial fibrillation 5 (71.4%) 8 (40%) 0.15 requiring cardioversion Median flutter cycle 258 (180-370) 252.5 (183-370) 0.34 length (range), ms Bidirectional block 93 (98.9%) 94 (100%) NA Isthmus dependent 85 (95.5%) 63 (90%) 0.29 Antiarrhythmic drugs 20 (21.3%) 15 (15.9%) 0.35 prescribed at discharge
Propafenone (Rythmol, Abbott, Chicago, IL, USA) is a group 1C antiarrhythmic drug that has sodium channel-blocking effects.
Multiple clinical trials have established the superiority of CA over antiarrhythmic drug therapy (AAD) for the maintenance of sinus rhythm and improvement of quality of life.
Treatment options for arrhythmic syncope include implantable cardiac pacemakers, defibrillators, antiarrhythmic drugs and catheter ablation.
Brugada syndrome is diagnosed in patients with Type 2 or Type 3 ST-segment elevation in [greater than or equal to]1 lead among the right precordial leads V1,V2 positioned in the 2nd, 3rd, or 4th intercostal space when a provocative drug test with intravenous administration of Class I antiarrhythmic drugs induces a Type 1 EKG morphology.
We then summarized the recent advances on the pharmacological effects of natural antiarrhythmic drugs in treating cardiac arrhythmia, exploring their potential mechanisms, and looking for novel targets.