Cardioactive glycoside, a subset of cardioactive steroids, that comes from the foxglove plant, Digitalis lanata
Inhibits Na+/K+ ATPase in the myocardium
Causes increase in intracellular sodium levels
Results in reversal of sodium-calcium exchanger
Normally imports three extracellular sodium ions into the cardiac myocyte in exchange for one intracellular calcium being exported
Sodium accumulates intracellularly and is exchanged for Calcium.
Causes an increase in the intracellular calcium concentration increasing contractility
Also a lengthening of phase 4 and phase 0 of the cardiac action potential which ultimately decreases heart rate
Summary
Inhibits NaK pump
Positive inotropy
Negative chronotropy/dromotropy
Indirect vagal stimulator
Causes increase in intracellular sodium levels
Results in reversal of sodium-calcium exchanger
Normally imports three extracellular sodium ions into the cardiac myocyte in exchange for one intracellular calcium being exported
Sodium accumulates intracellularly and is exchanged for Calcium.
Causes an increase in the intracellular calcium concentration increasing contractility
Also a lengthening of phase 4 and phase 0 of the cardiac action potential which ultimately decreases heart rate
Normally imports three extracellular sodium ions into the cardiac myocyte in exchange for one intracellular calcium being exported
Also a lengthening of phase 4 and phase 0 of the cardiac action potential which ultimately decreases heart rate
Inhibits NaK pump
Positive inotropy
Negative chronotropy/dromotropy
Indirect vagal stimulator
Positive inotropy
Indirect vagal stimulator
Increases vagal tone
At toxic levels,<unk>  can block the SA node's intrinsic impulses along with blocking AV nodal conductions
Can lead to bradyarrhythmias (esp in young)
Increases automaticity<unk>  acts on the Purkinje fibers by decreasing the resting potential, shortening the action potential duration, and causing enhanced automaticity leading to ventricular dysrhythmias (esp in elderly)
At toxic levels,<unk>  can block the SA node's intrinsic impulses along with blocking AV nodal conductions
Can lead to bradyarrhythmias (esp in young)<unk>  acts on the Purkinje fibers by decreasing the resting potential, shortening the action potential duration, and causing enhanced automaticity leading to ventricular dysrhythmias (esp in elderly)
Recent dose increase
Electrolyte Imbalance
Hypokalemia, Hyperkalemia, Hypomagnesemia, Hypercalcemia
Hypovolemia
Renal insufficiency
Cardiac Ischemia
Hypothyroidism
Meds
Calcium-Channel Blockers, Amiodarone
Hypokalemia, Hyperkalemia, Hypomagnesemia, Hypercalcemia
Calcium-Channel Blockers, Amiodarone
Plants that contain cardiac glycosides:
Oleander
Foxglove
Lily of the valley
Milkweed
Oleander
Foxglove
Lily of the valley
Milkweed
Digoxin toxicity
Cardiac
Beta-blocker toxicity
Inferior MI 
Amiodarone pulmonary toxicity
Sick sinus syndrome
Clonidine toxicity
Neurocardiogenic/reflex-mediated