NURS 3550H Lecture Notes - Lecture 4: Cardiac Glycoside, Digoxin, Inotrope
28 Dec 2018
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Document Summary
Belongs to family of drugs known as cardiac glycosides. Has profound effects on mechanical and electrical properties of the heart. Indicated for hf and control of dysrhythmias: when used for hf, does not prolong life (when used by women, may actually shorten life, now considered a second-line drug for treating hf. Digoxin exerts positive inotropic action on the heart. Drug increases the force of ventricular contraction and can thereby increase co. Increases myocardial contractility by inhibiting sodium, potassium-atpase enzyme. Calcium then augments contractile force by facilitating the interaction of myocardial contractile proteins: actin & myosin. Potassium ions compete with digoxin for binding to na, k-atpase. Potassium can impair therapeutic responses, in potassium can cause toxicity. By increasing contractility, digoxin shifts the relationship of fiber length to stroke volume in the failing heart toward that in a healthy heart. Consequences of increased cardiac output: sympathetic tone decreases, urine production increases, renin release declines.
