Cardiac Arrhythmias and Long QT Syndrome

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Questions and Answers

What medication should be given to a patient with Long QT syndrome in an acute setting?

Amiodarone

Magnesium sulfate (correct)

Beta blockers

Quinidine

Which classes of antiarrhythmic drugs increase the risk of QT prolongation?

Class I and Class II

Class II and Class IV

Class I and Class III (correct)

Class III and Class IV

What do patients typically feel when experiencing Torsades De Pointes?

Dizziness and fatigue

Shortness of breath

Skipped beats, palpitations, racing heart, chest discomfort/pain/pressure (correct)

Numbness and tingling

What takes longer in a long QT interval?

Repolarization Signup and view all the answers

Which class of antiarrhythmics decreases heart contractility by causing a blockade of calcium channels in the SA node AV node?

Class IV Signup and view all the answers

Which class of antiarrhythmics is Amiodarone a prototype drug for?

Class III Signup and view all the answers

True or false: all the drugs used to treat dysrhythmias can cause dysrhythmias.

True Signup and view all the answers

Beta blockers belong to which class of antiarrhythmics?

Class II Signup and view all the answers

What type of blockers prevent cardiac output?

Sodium Blockers Signup and view all the answers

What is the effect of Class I sodium channel blockers on action potentials?

Decrease action potential propagation Signup and view all the answers

What is the mechanism of action of Calcium Channel Blockers?

Inhibit calcium influx Signup and view all the answers

What is the effect of Class II antiarrhythmics on the heart?

Decrease heart rate Signup and view all the answers

What is the prototype drug for Class 1A sodium channel blockers?

Quinidine Signup and view all the answers

What is the major side effect of Amiodarone?

Pulmonary toxicity Signup and view all the answers

What is the effect of Potassium Channel Blockers on cardiac cells?

Decrease potassium efflux Signup and view all the answers

Which class of antiarrhythmics is associated with QT prolongation?

All of the above Signup and view all the answers

What is the effect of Class IV calcium channel blockers on the heart?

Decrease heart rate Signup and view all the answers

Which of the following is a side effect of Non-selective beta blockers?

Broncospasms Signup and view all the answers

What is the major risk associated with Class 1A sodium channel blockers?

QT prolongation Signup and view all the answers

Which class of antiarrhythmics does beta blockers belong to?

Class II Signup and view all the answers

What is the mechanism of action of beta blockers?

Decrease automaticity of the SA node Signup and view all the answers

What are the clinical uses of beta blockers?

Antihypertension, heart failure, angina, myocardial infarction, arrhythmias Signup and view all the answers

What type of arrhythmia is Amiodarone primarily indicated for?

Ventricular arrhythmia Signup and view all the answers

Can Amiodarone cross the blood-brain barrier?

Yes Signup and view all the answers

What is the side effect of Amiodarone?

Pulmonary toxicity, thyroid dysfunction, hepatotoxicity, optic neuropathy Signup and view all the answers

Which class of antiarrhythmics includes Amiodarone?

Class III Signup and view all the answers

What is the mechanism of action of Class III antiarrhythmics?

Block potassium channels preventing efflux of potassium Signup and view all the answers

Does Amiodarone accumulate in the tissues?

Yes Signup and view all the answers

Study Notes

Cardiac II

Long QT Syndrome

In an acute setting, magnesium sulfate should be given to a patient with Long QT syndrome.
Long QT syndrome is associated with delayed repolarization, when the heart is supposed to be relaxing but a beat hits into that relaxation period.

Antiarrythmic Drugs

Class I: Sodium channel blockers (Quinidine) and Class III: Potassium Channel Blockers (Amiodarone) increase the risk of QT prolongation.
Other medications associated with increased risk of QT prolongation include Antipsychotics, Antidepressants (mental health drugs), and antibiotics.

Torsedes De Pointes

A patient experiencing Torsedes De Pointes may feel skipped beats, palpitations, racing heart, and chest discomfort or pain/pressure.

Classes of Antiarrythmics

Class I sodium channel blockers are the largest group of antiarrhythmics.
Mnemonic to remember classes of antiarrhythmics: SODIUM BLOCKERS PREVENT CARDIAC OUTPUT
Class II: beta blockers, Class IV: Calcium Channel Blockers, and Class V: Others (Adenosine)

MOA of Class I Sodium Channel Blockers

Blocks sodium from entering nerve cells along the axon, which blocks action potentials along nerves in the heart, thus decreasing the speed of impulse across atria and ventricles.

Class 1A Sodium Channel Blockers

Prototype drug: Quinidine (PO), Procainamide (IV)
Major risks: QT prolongation

Beta Blockers

Belong to Class II antiarrhythmics
MOA: Decrease the automaticity of the SA node and slow the conduction through the AV node, helping control tachyarrythmias.
Clinical uses: Antihypertension, heart failure, angina, myocardial infarction, arrhythmias
First generation: Non-selective (Propranolol); cause bradycardia, hypotension, and broncospasms
Second generation: Beta 1 selective (Metoprolol, Atenolol); slow down heart rate. Preferred for patients with respiratory issues since it does not impact lungs.
Third generation: Non-selective with additional actions blocking B1, B2, and A1 adrenergic receptors (Carvedilol, labetelol); also blocks alpha 1 so it helps with hypertension.

Class III Antiarrythmics

Belong to Potassium Channel Blockers
MOA: Block potassium channels, preventing efflux of potassium from the cell, which leads to a delayed repolarization of the cardiac cell membrane.
Prototype drug: Amiodarone
Side effects: Pulmonary toxicity, thyroid dysfunction, hepatotoxicity, optic neuropathy, blue gray skin color changes. Also, hypotension, bradycardia, and QT prolongation.

Class IV Antiarrythmics

Belong to Calcium Channel Blockers
MOA: Slow down heart rate by inhibiting the influx of calcium ions during the cardiac action potential, particularly affecting the AV and SA nodes.

Class V Antiarrythmics

Include Atropine, Digoxin, and Adenosine

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Description

This quiz covers topics related to cardiac arrhythmias, including Long QT syndrome, medications that increase the risk of QT prolongation, and patient symptoms.