Type of Bradyarrhythmia | Causes and Mechanisms | Main ECG Findings |
---|---|---|
Sinus Bradycardia | 🔷 Physiological, particularly in athletes | |
🔷 Sinus node dysfunction (see sick sinus syndrome) | ||
🔷 Drugs ⇒ beta blockers, calcium channel blockers | 🔷 Rate < 60 bpm | |
🔷 Normal P wave before every QRS complex | ||
Tachycardia-Bradycardia Syndrome | 🔷 Abnormal supraventricular impulse generation and conduction | |
🔷 See sick sinus syndrome for details | 🔷 Intermittent tachyarrhythmias and bradyarrhythmias | |
Respiratory Sinus Arrhythmia | 🔷 Physiological, particularly in youths (A natural variation of the heart rate during respiration) | 🔷 Minor changes in the R-R interval during respiration ⇒ reduction during inspiration and increase during expiration |
Sinus Pause or Arrest | 🔷 May occur in healthy individuals | |
🔷 Underlying cardiovascular disease (see sick sinus syndrome) | 🔷 Transient (sinus pause) or complete (sinus arrest) absence of the P wave |
Benign ⇒ Sleep, well-conditioned athletes.
Drugs ⇒ Beta-blockers, calcium channel blockers (CCBs).
Pathologic ⇒ SA node disease, increased intracranial pressure (ICP), obstructive sleep apnea (OSA), hypothyroidism.
<aside> 💡 Increased ICP → Cushing triad
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Severe bradycardia and AV block during laparoscopy directly after Co2 insufflation is due to peritoneal stretching → Vagal stimulation → ↓↓ HR
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[A] Sinus bradycardia
Hemodynamically Stable
Hemodynamically Unstable
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Hemodynamically Unstable
Sinus bradycardia with sinus pause and junctional escape rhythm
<aside> 💡 Preferred initial diagnostic study ⇒ 12-lead ECG
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Chronotropic incompetence
[A]
[B]
[C]