Cardio: Class V Antiarrhythmics

Question 1

How does digoxin exert antiarrhythmic effects?

Answer 1

It directly stimulates the vagus nerve, leading to increased parasympathetic input on the SA and AV nodes –think of the “Las Vegas” sign next to DJ Foxglove.

Question 2

What kind of arrhythmias can digoxin treat?

Answer 2

Atrioventricular (such as atrial fibrillation represented by the TVs behind DJ Foxglove), because it controls the rate (which is the first priority in treatment of atrial fibrillation)

Question 3

What unique problem can magnesium treat?

Answer 3

Torsades The mechanism is not understood. (Think of the guy moonwalking over the torn torsades banners

Question 4

Severe muscle weakness is a symptom of _______-kalemia.

Answer 4

hypo

Question 5

A cardiac patient presenting with muscle weakness might have what ECG sign?

Answer 5

U waves (indicative of hypokalemia)

Question 6

The antiarrhythmic that is also a purine interacts with what cardiac receptor?

Answer 6

The A1 receptor (this being adenosine) (Think of the doorway allowing only A1-level swing dancers onto the floor.)

Question 7

What is the mechanism of adenosine?

Answer 7

It allows more potassium to exit the cell and less calcium to enter, allowing the membrane to remain negative and suppressing AV nodal action potentials. (Think of the swing dancers on the musical NODE – in the middle of the heart – with the banana flying up and the calci-yum fallen onto the ground.)

Question 8

What does adenosine do to the heart?

Answer 8

It temporarily causes heart block, thus being an ideal drug for treating supraventricular tachycardia.

Question 9

True or false: A1 stimulation can lead to vasodilation.

Answer 9

False. The A2 receptors (also stimulated by adenosine) mediate vasodilation.

Question 10

What two drugs can inhibit the effects of adenosine?

Answer 10

Caffeine and methylxanthine (represented by the guy drinking the xanthine energy drink, blocking the entrance to the Swing Dance podium)