ECG Cardiac Pharmacology 3

Question 1

Atropine is administered to a patient in symptomatic bradycardia. What is its mechanism of action on the heart?

Accepted Answer

Blocks muscarinic receptors, increasing heart rate

Answer

Atropine competitively blocks muscarinic (M2) receptors, removing vagal tone and allowing the SA node to increase its firing rate.

Question 2

Which medication used in ACLS for ventricular fibrillation works by blocking both sodium and potassium channels?

Accepted Answer

Amiodarone

Answer

Amiodarone is a Class III agent with Class I, II, and IV properties that blocks sodium, potassium, and calcium channels and is a first-line antiarrhythmic in VF/pVT.

Question 3

A patient in torsades de pointes should receive which treatment to stabilize cardiac membranes?

Accepted Answer

IV magnesium sulfate

Answer

Magnesium sulfate is the treatment of choice for torsades de pointes because it stabilizes cardiac membranes and suppresses early afterdepolarizations.

Question 4

Propranolol's cardiac effects are primarily due to blockade of which receptor?

Accepted Answer

Beta-1 adrenergic receptors

Answer

Propranolol is a non-selective beta-blocker that blocks beta-1 receptors in the heart, reducing heart rate, contractility, and conduction velocity.

Question 5

Which drug is given during CPR primarily to increase systemic vascular resistance and improve coronary perfusion pressure?

Accepted Answer

Epinephrine

Answer

Epinephrine stimulates alpha-1 receptors to cause vasoconstriction, increasing aortic diastolic pressure and coronary perfusion pressure during CPR.

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ECG Cardiac Pharmacology 3