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Questions and Answers
What is defined as a resting heart rate above 100 beats per minute in adults?
Which of the following is NOT a typical symptom experienced during arrhythmias?
Which category of arrhythmias includes ventricular fibrillation?
What treatment option is typically used for patients with a slow heart rate?
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Which type of tachycardia is characterized specifically by atrial flutter?
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What is a potential complication of certain arrhythmias?
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Which is an example of an extra beat arrhythmia?
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What class of drugs is often used to manage a fast heart rate during arrhythmias?
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What is one of the recommended strategies to ensure the absence of left atrial clot before cardioversion?
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Which group of medications is deemed harmful and not recommended for cardioversion?
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What is the treatment for unstable polymorphic ventricular tachycardia?
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What should be administered for stable polymorphic ventricular tachycardia?
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Which of the following is NOT a class I antiarrhythmic agent?
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What is the primary concern related to QTc prolongation in patients taking certain antiarrhythmic drugs?
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If atrial fibrillation lasts longer than 7 days, which drug is recommended for chemical cardioversion?
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What should be done if a patient is taking a drug that can prolong the QT interval?
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What is the initial treatment for symptomatic bradycardia if atropine fails to be effective?
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Which scenario requires urgent treatment with synchronized cardioversion?
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What is the maximum total dose of atropine that can be administered for symptomatic bradycardia?
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In the presence of Wolff-Parkinson-White syndrome, which medication should be avoided?
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What is a key consideration before performing cardioversion in patients with atrial fibrillation that has lasted more than 48 hours?
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When administering adenosine for paroxysmal supraventricular tachycardia (SVT), what is a critical action if initial doses fail?
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For a narrow complex tachycardia with a regular ventricular rhythm, what is a standard treatment option?
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What is the acceptable heart rate for patients with asymptomatic persistent atrial fibrillation at rest?
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What is the primary management for asymptomatic nonsustained ventricular tachycardia (VT)?
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What medication is considered the mainstay therapy for symptomatic nonsustained VT?
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In patients with structural heart disease (SHD) experiencing sustained VT, what is the immediate intervention?
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Which class of antiarrhythmic agents should be avoided in patients with heart failure?
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What is the recommended electrolyte level for potassium in the context of drug-induced QT prolongation?
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Which medication is contraindicated for patients with symptomatic heart failure and recently decompensated conditions?
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What should be done if significant QT prolongation is observed?
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What adverse effect is associated with class Ia medications in post-myocardial infarction survivors?
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Study Notes
Arrhythmia
- Irregularities in heartbeat, including when it is too fast or too slow.
- Resting heart rate above 100 beats per minute is tachycardia.
- Resting heart rate below 60 beats per minute is bradycardia.
- Some arrhythmias have no symptoms, while others can cause palpitations, lightheadedness, fainting, breathlessness, or chest pain.
- Most cases are not serious, but some increase risk of stroke or heart failure.
- Can be fatal in some cases.
Arrhythmia Categories
- Extra beats: premature atrial, ventricular, and junctional contractions occur due to an extra beat.
- Supraventricular tachycardias: atrial fibrillation, atrial flutter, and paroxysmal supraventricular tachycardia originate from upper chambers of the heart.
- Ventricular arrhythmias: ventricular fibrillation and ventricular tachycardia originate from lower chambers of the heart.
- Bradyarrhythmias: caused by sinus node dysfunction or atrioventricular conduction disturbances.
Arrhythmia Treatment
- Medications, medical procedures, and surgery can effectively treat many arrhythmias.
- Beta blockers and antiarrhythmic agents like procainamide are used for fast heart rates.
- Pacemakers are used for slow heart rates.
- Blood thinners are given to reduce complications in those with irregular heartbeats.
- Cardioversion or defibrillation using controlled electric shock can be urgently used for severe symptoms or instability.
Symptomatic Bradycardia Treatment
- Unstable patients with low blood pressure, altered mental state, shock signs, chest pain, or acute heart failure require treatment:
- Atropine 0.5 mg every 3-5 minutes, maximum dose 3 mg
- If Atropine fails, consider transcutaneous pacing, dopamine 5-20 mcg/kg/minute, or epinephrine 2-10 mcg/minute.
Symptomatic Tachycardia Treatment
- Unstable patients require synchronized cardioversion.
- If stable, assess whether the QRS complex is narrow or wide.
- Narrow complex tachycardia (QRS less than 120 milliseconds): Usually atrial arrhythmias
- Regular ventricular rhythm: supraventricular tachycardia or sinus tachycardia likely.
- Vagal maneuvers or adenosine 6 mg IV push, followed by 20 mL saline flush, then 12 mg IV push.
- Higher doses may be needed for patients taking theophylline or caffeine.
- Initial dose should be reduced to 3 mg in patients taking dipyridamole or carbamazepine, after heart transplantation, or if the drug is given through central access.
- Use adenosine cautiously in severe coronary artery disease (CAD).
- Don't give adenosine to patients with asthma.
- Don't give for unstable, irregular, or polymorphic wide complex tachycardias.
- If vagal maneuvers or adenosine fail, consider calcium channel blockers (CCBs) or beta-blockers.
- Avoid verapamil, diltiazem, and digoxin in Wolff-Parkinson-White syndrome.
- Irregular ventricular rhythm: atrial fibrillation (or possibly atrial flutter)
- If hemodynamically stable, manage rapid ventricular rate with nondihydropyridine CCBs (diltiazem, verapamil), beta-blockers, or digoxin.
- Rate is acceptable if it is less than 110 beats/minute at rest in asymptomatic persistent atrial fibrillation.
- If hemodynamically unstable, synchronized cardioversion is recommended.
- Patients with AF for over 48 hours are at high risk of cardioembolic events; don't immediately cardiovert if stable.
- Transesophageal echocardiography before cardioversion can confirm absence of left atrial clot.
- Thromboembolic event risk is highest within 10 days following (both pharmacologic and electrical) cardioversion.
- If atrial fibrillation duration is up to 7 days, consider elective direct current conversion or chemical cardioversion:
- Flecainide, dofetilide, propafenone, ibutilide, or amiodarone may be used
- Digoxin and sotalol are not recommended due to potential harm.
- Disopyramide, quinidine, and procainamide are less effective.
- If atrial fibrillation duration is greater than 7 days, consider elective direct current conversion or chemical cardioversion with dofetilide, amiodarone, or ibutilide.
- Regular ventricular rhythm: supraventricular tachycardia or sinus tachycardia likely.
- Wide complex tachycardia (QRS greater than 120 milliseconds): Usually ventricular arrhythmias
- Regular ventricular tachycardia (VT)
- Adenosine can be considered only if regular and monomorphic.
- Intravenous procainamide, amiodarone (or sotalol); lidocaine as a second line.
- Avoid procainamide and sotalol if prolonged QTc.
- Polymorphic (irregular) VT: (torsade de pointes), primarily induced when QTc interval is over 500 milliseconds.
- If unstable, immediate defibrillation is required.
- If stable, intravenous magnesium 1- to 2-gram IV bolus, maximum 16 g/24 hours.
- Regular ventricular tachycardia (VT)
- QT-prolonging medications should be withdrawn if QTc interval is greater than 450 milliseconds. Electrolytes, thyroid function, and drug interactions should be assessed.
- Electrolyte levels should be maintained at optimal levels (K+ greater than 4 mmol/L and less than 5 mmol/L, Mg++ greater than 2 mg/dL).
Vaughan-Williams AAD Classes
- Class I/Na+ channel blockers:
- Ia (intermediate): Disopyramide, Quinidine, and Procainamide
- Ib (fast): Lidocaine, Mexiletine, and Phenytoin
- Ic (slow): Flecainide, Propafenone, and Encainide
- Class II β-Blockers: Metoprolol, Esmolol, and Atenolol
- Class III K+ channel blockers: Sotalol, Amiodarone, Dronedarone, Dofetilide, and Ibutilide
- Class IV Ca2+ channel blockers: Diltiazem and Verapamil
Management of Ventricular Arrhythmias
- Nonsustained VT:
- Asymptomatic:
- Infrequent ventricular ectopic beats:
- No treatment needed for patients without structural heart disease or inherited arrhythmia disorder.
- Infrequent ventricular ectopic beats:
- Symptomatic:
- Beta-blockers:
- Considered mainstay therapy.
- Effective in suppressing ventricular ectopic beats and reducing sudden cardiac death (SCD) across a spectrum of cardiac disorders.
- Nondihydropyridine CCBs are an alternative for patients without structural heart disease.
- Antiarrhythmic drugs (AAD) (amiodarone, flecainide, mexilitine, propafenone, sotalol) can be added.
- Beta-blockers:
- Asymptomatic:
- Sustained VT:
- Immediate defibrillation if pulseless.
- Synchronized cardioversion if VT with pulse.
- Implantable cardioverter defibrillator (ICD) for structural heart disease (SHD) with beta-blockers, amiodarone, or sotalol.
Arrhythmias in Special Patient Populations
- Heart failure:
- Avoid Class Ia and Class Ic agents.
- Amiodarone and dofetilide (for atrial arrhythmias only) have a neutral effect on mortality after myocardial infarction (MI) in patients with left ventricle dysfunction.
- Dronedarone (for atrial arrhythmias only) is contraindicated in patients with symptomatic heart failure with recent decompensation requiring hospitalization or NYHA Class IV symptoms.
- Acute MI:
- Avoid Class Ia and Class Ic agents.
- Class Ia medications are linked to increased mortality in post-MI survivors.
- Amiodarone and dofetilide (for atrial arrhythmias only) have a neutral effect on mortality after MI in patients with left ventricle dysfunction.
Drug-Induced Arrhythmias
- Drug-induced QT prolongation:
- Discontinue the offending agent if QT prolongation is significant (greater than 450 milliseconds).
- Ensure proper renal and hepatic dosing adjustments.
- Review electrolyte abnormalities and thyroid function tests.
- Make sure all electrolytes are maintained at critical levels (K+ greater than 4 mmol/L and less than 5 mmol/L, Mg++ greater than 2 mg/dL).
- Drug-induced bradycardia or atrioventricular block:
- Beta-blockers, CCBs, digoxin are possible causes.
- Administer appropriate antidote (e.g., calcium for CCB toxicity).
- Review for drug interactions, as antiarrhythmic agents can have interactions that result in significant outcomes.
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Description
Test your knowledge about arrhythmias, including their types, causes, symptoms, and potential treatments. Explore the difference between tachycardia and bradycardia, along with the significance of various arrhythmia categories. This quiz will help you understand the complexities of heart conditions and their implications.
