Cardio: Digoxin, Milrinone, and Nesiritide

Question 1

What is the mechanism of digoxin?

Answer 1

It inhibits the Na/K pump, preventing sodium from being pumped out and potassium from being pumped in. The excess intracellular sodium then leaves the cell through increase Na/Ca exchange, thereby providing more calcium for the sarcoplasmic reticulum. (Think of the coach with peanuts, unable to leave the gym and the Calci-Yum sneaking in through the door opened by the kid sneaking out with peanuts.)

Question 2

Other than systolic heart failure, digoxin can also treat _____________.

Answer 2

atrial arrhythmias, because it has a greater effect on the atria (due to vagal stimulation which is felt greatest in the atria)

Question 3

_____________ is an indicator of digitalis toxicity.

Answer 3

Hyperkalemia

Question 4

Those with digoxin toxicity often have what symptom?

Answer 4

PVCs

Question 5

Long-term digoxin use can lead to what ECG finding?

Answer 5

“Scooped” ST segments (Think of the high schooler scooping the taSTy ice cream.)
This is NOT a sign of toxicity

Question 6

Because digoxin stimulates vagus nerve activity, it can lead to ______________.

Answer 6

bradycardia from SA node slowing
(Think of the Las VeGaS theme –representing increased vagal nerve tone –with John Cusack on the SA node holding a dangling heart-shaped pocket watch.)

Question 7

Digoxin should be used in extreme caution with drugs that _______________.

Answer 7

can cause heart block (like beta-blockers); this is because digoxin can also cause AV nodal heart block
(Think of the girl on the dance floor blocking the guy’s advances at the AV node location; also, the exit to the gym needs to remain unßlocked.)

Question 8

Common side effects of digoxin include _________________.

Answer 8

xanthopsia (objects appearing yellow) and GI upset

Think of the guy in the dance hall about to vomit –he’s bathed in a yellow spotlight.

Question 9

Why does hypokalemia increase risk of digoxin toxicity?

Answer 9

Because more digoxin binds when there is less potassium to bind (Think of the additional vending machine getting pushed up against the wall when its bananas have been depleted.)

Question 10

What can increase the half life of digoxin?

Answer 10

• Kidney failure- Antiarrhythmic drugs (Think of the overturned, kidney-shaped juke box, with the rival high schooler standing over it with a long, tapering flag. There are also records thrown over the floor –symbolizing antiarrhythmics like verapamil and amiodarone that can prevent renal clearance of digoxin.)

Question 11

What can treat digoxin overdose?

Answer 11

Digoxin Fab! (Just like the FABulous Las Vegas theme!)

Question 12

What is the mechanism of milrinone?

Answer 12

It is a phosphodiesterase inhibitor that leads to increased inotropy and arteriolar vasodilation.
(Think of the politician with the cAMPaign: “one in a MILlion.” He is trying to PHOSter interest. He also has floppy dilated ears.)

Question 13

What is the mechanism of nesiritide?

Answer 13

It is a BNP analog, stimulating vasodilation of arteries and veins as well as diuresis of sodium.
(Think of the elephant with the dilated arterial trunk and venous legs who is pouring out water onto peanuts.)

Question 14

True or false: milrinone and nesiritide are acute agents.

Answer 14

True! (Think of the “Acute Issues” campaign.)

Question 15

What antiarrhythmics can decrease the clearance of digoxin?

Answer 15

Verapamil
Amiodarone
Quinidine

Question 16

T or F: digoxin decrease the mortality of those with chronic HF

Answer 16

FALSE

Digoxin only decrease symptoms and therefore is not the first line agent for treatment of chronic HF

Question 17

What is the treatment of digoxin toxicity?

Answer 17

Anit-digoxin Fab fragments

also normalize K and give Mg