Pharmacology Ch. 45: Antiarrhythmic Agents

Adverse effects of class IV anti arrhythmic drugs (Diltiazem)

-Related to vasodilation of blood vessels throughout the body -CNS effects -GI effects -Hypotension, HF, shock, arrhythmias, AV block, edema

Class 0 of Antiarrhythmic Agents include...

ACE and ARBs

Class 2 of Antiarrhythmic Agents include...

Act on autonomic receptors

The action potential of cardiac muscle cells consists of how many phases? Three Four Five Six

Five

Phase 2

(plateau stage) Occurs as the cell membrane becomes less permeable to potassium and calcium slowly enters the cell

Indication of class IV anti arrhythmic drugs (Diltiazem)

-Antihypertensives -Treatment of angina -Treatment of rapid supraventricular dysrhythmias

Drug-drug interactions of class II antiarrhythmic drugs (Propranolol)

-Verapamil -Antidiabetic medications -Methylxanthines (theophylline and caffeine)

What is the drug of choice to treat supraventricular tachycardia (SVT)? Atenolol Amlodipine Atropine Adenosine

Adenosine

MOA of class IV anti arrhythmic drugs (Diltiazem)

-Blocks the movement of calcium ions across the cell membrane - Depressing the generation of action potential -Delaying phases 1 and 2 of repolarization -Slow conduction through the AV node

Adverse effects of class 1 antiarrhythmic drugs (Lidocaine)

-CNS effects: Dizziness, fatigue, slurred speech -GI - Nausea and vomiting -CV - Arrhythmias -Respiratory depression -Misc. - Rash, loss of hair, and potential bone marrow suppression

MOA of class II antiarrhythmic drugs (Propranolol)

-Competitively block beta receptor sites in the heart and kidneys -Decrease heart rate, cardiac excitability, and cardiac output -Slow conduction though the AV node -decreased renin

Causes of Cardiac Arrhythmias

-Electrolyte disturbances that alter the action potential -Decreases in oxygen delivered to the cells -Structural damage changing the conduction pathway through the heart -Acidosis or accumulation of waste products altering the action potential -Drugs that alter the action potential or cardiac conduction

What must you assess when administering any of these antiarrhythmic drugs to a pt?

-History and Physical Exam; Known allergy -Impaired kidney or liver function, heart block, HF, hypotension, shock, respiratory dysfunction, electrolyte disturbances -Pregnancy and lactation, neurological and cardiac status, respirations, baseline ECG and appropriate lab values

Indications of class III anti-arrhythmic drugs (Amiodarone)

-Life-threatening ventricular arrhythmias -Maintenance of sinus rhythm after conversion of atrial arrhythmias

Indication for class 1 antiarrhythmic drugs (Lidocaine)

-Management of acute ventricular arrhythmias during cardiac surgery or MI -Preferable in conditions such as tachycardia

Adverse effects of class III anti-arrhythmic drugs (Amiodarone)

-Related to changes in action potentials Common: nausea, vomiting, weakness, dizziness, hypotension -Bradycardia or AV block that could progress to HF

Adverse effects of class II antiarrhythmic drugs (Propranolol)

-Related to the effects of blocking beta receptors in the sympathetic nervous system -CNS - Dizziness, insomnia, dreams, and fatigue -CV - Hypotension, bradycardia, AV block, arrhythmias -Respiratory - Bronchospasm and dyspnea -GI - Nausea, vomiting, anorexia -Misc. - Loss of libido, decreased exercise tolerance, alterations in blood glucose levels

MOA of class 1 antiarrhythmic drugs (Lidocaine)

-Stabilize cell membrane by binding to sodium channels, depressing phase 0 of action potential and changing duration of action potential -Decreases depolarization, decreasing automaticity of the ventricular cells; increases ventricular fibrillation threshold

Types of Cardiac Arrhythmias

-Tachycardia (faster-than-normal heart rate) -Bradycardia (slower-than-normal heart rate) -Premature atrial contractions (PACs) or premature ventricular contractions (PVCs) -Atrial flutter -Atrial fibrillation or ventricular fibrillation -Alterations in conduction through the muscle (heart blocks and bundle branch blocks)

Class 3 Antirrhythmic Agents

Act on potassium channels

According to the American Heart Association's Advanced Cardiac Life Support guidelines, which is one of the drugs of choice for treating ventricular fibrillation or pulseless ventricular tachycardia in cardiac arrest situations? Amiodarone Dofetilide Ibutilide Sotalol

Amiodarone

A patient has been diagnosed with atrial fibrillation. What class of medications is expected to be prescribed? Anticholinergics Anticoagulants Proton pump inhibitors Histamine blockers

Anticoagulants -to prevent blood pooling in the ventricles and causing clots, which can lead to pulmonary embolism or stroke.

MOA of class III anti-arrhythmic drugs (Amiodarone)

Block potassium channels and slow the outward movement of potassium during phase 3 of the action potential - This action prolongs the action potential

What is the priority intervention for a patient in ventricular fibrillation? Defibrillation Cardioversion Notifying the family Continue to monitor

Defibrillation

Phase 0

Depolarization. Na+ rapidly enters the cell. Charge gets more +. Happens very fast. Occurs when the cell reaches a point of stimulation.

Drug-drug interactions of class 1 antiarrhythmic drugs (Lidocaine)

Foods that alkalinize the urine (citrus juice, vegetables, antacids, milk products) -Grapefruit juice

In order to prevent toxic effects, patients taking quinidine should avoid what juice? Apple Cranberry Grapefruit Tomato

Grapefruit

Which drug is used to treat life-threatening arrhythmias during myocardial infarctions or cardiac surgery? Lidocaine (Xylocaine) Flecainide (generic) Propafenone (Rythmol) Adenosine (generic)

Lidocaine (Xylocaine)

Class 4 of antiarrhythmic agents include...

Modulate calcium channels

What are the lifespan considerations for older adults using antiarrhythmic agents?

Older adults frequently are prescribed one of these drugs. Older adults are more likely to have renal and/or hepatic impairment related to underlying medical conditions, which could interfere with the metabolism and excretion of these drugs. · The dosage for an older adult may need to be started at a lower level than that recommended for other adults. The patient should be monitored closely and the dose adjusted based on patient response. If other drugs are added or removed from the drug regimen, appropriate dose adjustments may need to be made.

Phase 3

Period of rapid repolarization as the calcium influx stops

Which class I antiarrhythmic drug can be given IV, IM, or orally to treat atrial arrhythmias? Disopyramide Quinidine Procainamide Propranolol

Quinidine

What is the conducting system of the heart?

SA node, AV node, bundle of His, bundle branches, and Purkinje fibers

What should you caution when administering a class III anti-arrhythmic drug (Amiodarone) to a pt?

Shock, hypotension, respiratory depression, prolonged QT interval, renal or hepatic disease

Which are causes of bradycardia? Select all that apply. Fever Sleeping Infection Vagal nerve stimulation Spinal cord injury

Sleeping, Vagal nerve stimulation, Spinal cord injury

Class 1 of Antiarrhythmic Agents include...

Sodium channel blockers

What is the best way to treat sinus tachycardia? Administer beta blockers. Encourage deep breathing exercises. Treat the underlying cause. Cardiovert.

Treat the underlying cause.

Indications of class II antiarrhythmic drugs (Propranolol)

Treatment of rapid AF, atrial flutter, paroxysmal SVTs, hypertension angina, PVCs, ventricular tachycardia

Phase 1

early repolarization -Short period when the fast sodium ion channels close and there is decreased permeability of sodium

Phase 4

resting membrane potential