Sinus Arrhythmia

• Irregular P-P interval
• No pacemaker unless symptomatic sinus bradycardia

Sinoatrial Exit Block

• No p wave during the pause and then the next p wave comes on time buried in the junctional escape beat

Sinus Pause/Arrest

• No p wave for over 3 seconds

Sinus Node Dysfunction

Sinus Node Dysfunction

• Sinus bradycardia: Sinus rate <50 bpm
• Ectopic atrial bradycardia: Atrial depolarization attributable to an atrial pacemaker other than the sinus node with a rate <50 bpm
• Sinoatrial exit block: Evidence that blocked conduction between the sinus node and adjacent atrial tissue is present. Multiple electrocardiographic manifestations including “group beating” of atrial depolarization and sinus pauses.
• Sinus pause: Sinus node depolarizes >3 s after the last atrial depolarization
• Sinus node arrest: No evidence of sinus node depolarization
• Tachycardia-bradycardia (“tachy-brady”) syndrome: Sinus bradycardia, ectopic atrial bradycardia, or sinus pause alternating with periods of abnormal atrial tachycardia, atrial flutter, or AF.
• Chronotropic incompetence: Broadly defined as the inability of the heart to increase its rate commensurate with increased activity or demand, in many studies translates to failure to attain 80% of expected heart rate reserve during exercise.
• Isorhythmic dissociation: Atrial depolarization (from either the sinus node or ectopic atrial site) is slower than ventricular depolarization (from an atrioventricular nodal, His bundle, or ventricular site).

Pacemaker?

Note: no time stipulation for pauses

2:1 AV Block

• Wide QRS makes Mobitz II more likely
• Normal PR makes Mobitz I less likely

Pacemaker?

Mobitz I (Wenckebach)

• Group beating should clue Type 2 AV Block
• Prolonging PR clue to Mobitz 1
• Compare PR before and after drop

Pacemaker?

Complete Heart Block

• More Ps than Qs
• Dissociated
• QRS are regular

Pacemaker?

Temporary Transvenous?

Alternating Bundles

• Sinus bradycardia with sinus arrhythmia with 1st degree A-V block with occasional with 2nd degree A-V block (Mobitz I) , 2:1 av-block , Premature ventricular complexes with ventricular escape complexes

• Intermittent Left bundle branch block and Right bundle branch block complexes

High Grade AV Block

• Two consecutive p waves that don't conduct

Pacemaker?

AV Block

• First-degree atrioventricular block: P waves associated with 1:1 atrioventricular conduction and a PR interval >200 ms
• Second-degree atrioventricular block: P waves with a constant rate (<100 bpm) where atrioventricular conduction is present but not 1:1
  • Mobitz type I: P waves with a constant rate (<100 bpm) with a periodic single nonconducted P wave associated with P waves before and after the nonconducted P wave with inconstant PR intervals
  • Mobitz type II: P waves with a constant rate (< 100 bpm) with a periodic single nonconducted P wave associated with other P waves before and after the nonconducted P wave with constant PR intervals (excluding 2:1 atrioventricular block)
  • 2:1 atrioventricular block: P waves with a constant rate (or near constant rate because of ventriculophasic sinus arrhythmia) rate (<100 bpm) where every other P wave conducts to the ventricles
  • Advanced, high-grade or high-degree atrioventricular block: 2 consecutive P waves at a constant physiologic rate that do not conduct to the ventricles with evidence for some atrioventricular conduction
• Third-degree atrioventricular block (complete heart block): No evidence of atrioventricular conduction
• Vagally mediated atrioventricular block: Any type of atrioventricular block mediated by heightened parasympathetic tone
• Infranodal block: Atrioventricular conduction block where clinical evidence or electrophysiologic evidence suggests that the conduction block occurs distal to the atrioventricular node

Pacemaker?