Antiarrythmics - Miscelaneous

Question 1

How does adenosine work?

Answer 1

• activation of inward rectifier K+ channels (K+r) and inhibition of L-type Ca2+ channels.
• Results in hyper-polarization and suppression of Ca2+ dependent AP (nodal tissue)

Question 2

How does digitalis work?

Try to get detailed!

Answer 2

activation of vagal efferent nerves to the heart:
-Reduces the conduction in the AV node, leading to partial block and ventricular rate falls.
-Inhibits Na+/K+/ATPase pumps: increases intracellular Na+ concentration -> reverses action on Na+/Ca2+ exchanger -> more Ca2+ into cell -> improves cardiac contractility (binds to troponin).
Increased SV -> increased CO -> decreased HR!

Question 3

Which of these two is the drug of choice for prompt conversion of paroxysmal SVT?

Answer 3

Adenosine!

Question 4

Which one of these two is short-acting so that you can halt side effects shortly after stopping the administration?

Answer 4

Adenosine!

Question 5

Which of these drugs has a side effect of extreme AV block?

And with overdose it can cause nausea, vomiting diarrhea, xanthopsia, halos, arrhythmias, tremors, seizure, and death?

Answer 5

Digitalis. Yikes.

Question 6

How is digitalis eliminated?

Answer 6

Kidneys! (so watch out for peeps with renal failure)

Question 7

What are the contraindications for use of these meds?

Answer 7

Both contraindicated in heart block

Digitalis also contraindicated in hypokalemia and Wolf-Park.-White

Question 8

What is the therapeutic use of digitalis?

Answer 8

• Heart failure

- Reduces ventricular rate when it is being driven by high atrial rate (fibrillation or flutter)