Digitalis, cardiac effects

Cardiac effects Use with caution and in lower doses in patients with CHF, reduced cardiac output, digitalis toxicity accompanied by AV block and in the elderly. 

In the process of observing the pharmacological effects of Digitalis, Withering identified desired endpoints to include increased urine production (now believed to be the result of increased cardiac output and increased blood flow through the kidneys) and a decreased pulse rate. He also noted the toxic central and cardiac effects... 

Ventricular extra beats, including coupled beats (that is ventricular bigeminy), are the most common cardiac effects of digitalis toxicity, although they are not specific. In more severe cases ventricular tachycardia, bidirectional tachycardia, and ventricular fibrillation can occur. There have also been reports of accelerated idioventricular rhythm (41,42). 

The risk of digitalis toxicity during the therapeutic use of cardiac glycosides is similar in children to that in adults, ranging in 12 separate published series from 12 to 50% (median 21%) (141). The most common non-cardiac effects are vomiting and feeding problems, and the most common cardiac effects are conduction defects, particularly atrioventricular block and ectopic rhythms, although (as in adults) any dysrhythmia can occur. 

Red squill contains many cardiac glycosides, the most prominent being scillaren A and scilliroside. These glycosides produce digitalis-like effects when ingested and, like digitalis, inhibit Na/K ATPase, block AV conduction, and cause sinus bradycardia. 

Alteration of the movement of ions, such as potassium, in heart tissue may be a toxic response to some foreign compounds. For example, the digitalis glycosides cause changes in tissue potassium and this may lead to serious cardiac effects. Diuretics may also cause low plasma potassium with potentially dangerous effects on heart function. 

The cardiac glycosides are a group of plant materials arbitrarily so named because of their specific digitalis-like effect on the heart muscle. Their physiological activity is primarily dependent on the nature of the aglycon rather than on the carbohydrate component. For their discovery, we are indebted to studies of medicinal and poisonous plants, especially of... 

One of the major side effects of using a loop diuretic Is excessive excretion of electrolytes. Including potassium Ions. Loss of potassium can eventually lead to hypokalemia (low blood potassium), and hypokalemia alone can lead to the development of cardiac arrhythmias. Potassium loss, however, also potentiates the actions of digitalis (cardiac sodlum-potassium-adenosine triphosphatase Inhibition) and can lead to digitalis-induced cardiac arrhythmias as well. Hypokalemia can be treated/prevented by the use of potassium supplements or the use of a potassiumsparing diuretic (e.g., triamterene and amiloride). Because potassium-sparing diuretics are weakly basic drugs, they do not alter the active secretion of loop diuretics. 

Cardiac glycosides Digitalis-like effects thiazines, sedatives, alcohol Potentiation of digitalis... 

Dlgltoxin. Digitoxin is a cardiac glycoside obtained from Digitalis purpurea. Digitoxin is indicated in the treatment of atrial flutter, atrial fibrillation, and supraventricular tachycardia. Its electrophysiologic and adverse effects are similar to those described for digoxin (87). 

Calcium is contraindicated in patients with hypercalcemia or ventricular fibrillation and in patients taking digitalis. Calcium is used cautiously in patients with cardiac disease. Hypercalcemia may occur when calcium is administered with the thiazide diuretics. When calcium is administered with atenolol there is a decrease in Hie effect of atenolol, possibly resulting in decreased beta blockade. There is an increased risk of digitalis toxicity when digitalis preparations are administered with calcium. The clinical effect of verapamil may be decreased when the drug is administered with calcium. Concurrent ingestion of spinach or cereal may decrease file absorption of calcium supplements. 

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