Heart Failure and Antidysrhythmics. Pharmacology NUR 3703 By Linda Self. Review of Heart. Unique properties of heart: Contractility Conductivity Excitability. Layers of Heart. Pericardium Myocardium epicardium. Conduction of the Heart. SA node Internodal tracts AV node/junction
By Linda Self
CO=SV x HR
Digoxin (Lanoxin)—cardiac glycoside. Therapeutic levels are 0.5-2.0 ng/mL (in renal failure and the elderly, therapeutic level is .5-1.3).
Works by inhibition of Na, K-ATPase, enzyme affects sodium and calcium exchange after contraction, results in greater availability of calcium to activate actin and myosin w/ resultant increased cardiac contractility.
RMP Ca++ Ca++ K+ Na+ K+
Re-entry—the diversion of a repolarization wave from a direction in which it is blocked to another in which it is not. The wave then goes back up the original pathway to produce a contraction. This leads to a continuing series of premature beats.