Understanding Arrhythmia

Study Notes

Irregularities in the heartbeat, can be either too fast or too slow.
A resting heart rate above 100 beats per minute is tachycardia, below 60 beats per minute is bradycardia
Some arrhythmias have no symptoms, while other may have symptoms like palpitations, feeling a pause between heartbeats, lightheadedness, passing out, shortness of breath or chest pain.
Most cases of arrhythmia are not serious, but some can lead to stroke, heart failure, or even sudden death.

Extra beats: premature atrial contractions, premature ventricular contractions, and premature junctional contractions.
Supraventricular tachycardias: atrial fibrillation, atrial flutter, and paroxysmal supraventricular tachycardia.
Ventricular arrhythmias: ventricular fibrillation and ventricular tachycardia.
Bradyarrhythmias: due to sinus node dysfunction or atrioventricular conduction disturbances.

Many arrhythmias can be treated effectively.
Treatments include medications, medical procedures, and surgery.
Medications for a fast heart rate include beta blockers and antiarrhythmic agents like procainamide.
Pacemakers are often used for slow heart rates.
Blood thinners are used to reduce the risk of complications for patients with an irregular heartbeat.
Severe symptoms or medical instability may require urgent treatments like cardioversion or defibrillation.

Unstable is defined as hypotension, acutely altered mental status, signs of shock, ischemic chest discomfort, or acute heart failure.
Treatment options:
- Atropine 0.5 mg every 3–5 minutes (maximum dose 3 mg).
- If atropine fails, use transcutaneous pacing, dopamine 5–20 mcg/kg/minute, or epinephrine 2–10 mcg/minute.

Unstable: synchronized cardioversion
Stable:
- Determine if QRS complex is narrow or wide:
  - Narrow complex tachycardia (QRS less than 120 milliseconds): Usually atrial arrhythmias
    - Regular ventricular rhythm: Supraventricular tachycardia (SVT) or sinus tachycardia likely. Treatment:
      - Vagal maneuvers or adenosine 6-mg intravenous push, followed by a 20-mL saline flush, then a 12-mg intravenous push (may repeat once).
  - Irregular ventricular rhythm: Atrial fibrillation (or possibly atrial flutter)
    - Hemodynamically stable: General management should focus on control of the rapid ventricular rate. Treatment: Usually nondihydropyridine CCBs (diltiazem, verapamil) or β-blockers; digoxin is sometimes useful.
    - Hemodynamically unstable: Synchronized cardioversion recommended.
      - Patients with AF for more than 48 hours are at high risk of cardioembolic events and should not be immediately cardioverted if stable.