Heart Arrhythmias

• • Irregular atrial and ventricular rhythms.
  • Normal P wave preceding each QRS complex.

  Sinus Arrhythmia
• • Atrial and ventricular rhythms are regular.
  • Rate > 100 bpm.
  • Normal P wave preceding each QRS complex.

  Sinus Tachycardia
• • Regular atrial and ventricular rhythms.
  • Rate < 60 bpm.
  • Normal P wave preceding each QRS complex.

  Sinus Bradycardia
• • Atrial and ventricular rhythms normal except for missing complex.
  • Normal P wave preceding each QRS complex.
  • Pause not equal to multiple of the previous rhythm.

  Sinoatrial (SA) arrest or block
• • Atrial and ventricular rhythms vary slightly.
  • Irregular PR interval.
  • P waves irregular with changing configurations indicating that they aren’t all from SA node or single atrial focus; may appear after the QRS complex.
  • QRS complexes uniform in shape but irregular in rhythm.

  Wandering atrial pacemaker
• • Premature, abnormal-looking P waves that differ in configuration from normal P waves.
  • QRS complexes after P waves except in very early or blocked PACs.
  • P wave often buried in the preceding T wave or identified in the preceding T wave.


  Premature atrial contraction (PAC)
• • Atrial and ventricular rhythms are regular.
  • Heart rate > 160 bpm; rarely exceeds 250 bpm.
  • P waves regular but aberrant; difficult to differentiate from preceding T wave.
  • P wave preceding each QRS complex.
  • Sudden onset and termination of arrhythmia
  • When a normal P wave is present, it’s called paroxysmal atrial tachycardia; when a normal P wave isn’t present, it’s called paroxysmal junctional tachycardia.


  Paroxysmal Supraventricular Tachycardia
• • Atrial rhythm regular, rate, 250 to 400 bpm
  • Ventricular rate variable, depending on degree of AV block
  • Saw-tooth shape P wave configuration.
  • QRS complexes uniform in shape but often irregular in rate.

  Atrial flutter
• • Atrial rhythm grossly irregular rate > 300 to 600 bpm.
  • Ventricular rhythm grossly irregular, rate 160 to 180 bpm.
  • PR interval indiscernible.
  • No P waves, or P waves that appear as erratic, irregular base-line fibrillatory waves

  Atrial Fibrillation
• • Atrial and ventricular rhythms are regular.
  • Atrial rate 40 to 60 bpm.
  • Ventricular rate usually 40 to 60 bpm.
  • P waves preceding, hidden within (absent), or after QRS complex; usually inverted if visible.
  • PR interval (when present) < 0.12 second
  • QRS complex configuration and duration normal, except in aberrant conduction.

  Junctional Rhythm
• • Atrial and ventricular rhythms are irregular.
  • P waves inverted; may precede be hidden within, or follow QRS complex.
  • QRS complex configuration and duration normal.

  Premature Junctional Conjunctions
• • Atrial and ventricular rhythms regular
  • PR interval > 0.20 second.
  • P wave preceding each QRS complex.
  • QRS complex normal.

  First-degree AV block
• • Atrial rhythm regular.
  • Ventricular rhythm irregular.
  • Atrial rate exceeds ventricular rate.
  • PR interval progressively, but only slightly, longer with each cycle until QRS complex disappears.
  • PR interval shorter after dropped beat.

  Second-degree AV block Mobitz I (Wenckebach)
• • Atrial rhythm regular.
  • Ventricular rhythm regular and rate slower than atrial rate.
  • No relation between P waves and QRS complexes.
  • No constant PR interval.
  • QRS interval normal (nodal pacemaker) or wide and bizarre (ventricular pacemaker)

  Third-degree AV block (complex heart block)
• • Atrial rhythm regular
  • Ventricular rhythm irregular
  • QRS complex premature, usually followed by a complete compensatory pause
  • QRS complex wide and distorted, usually >0.14 second.
  • Premature QRS complexes occurring singly, in pairs, or in threes; alternating with normal beats; focus from one or more sites.
  • Ominous when clustered, multifocal, with R wave on T pattern.

  Premature ventricular contraction (PVC)
• • Ventricular rate 140 to 220 bpm, regular or irregular.
  • QRS complexes wide, bizarre, and independent of P waves
  • P waves no discernible
  • May start and stop suddenly

  Ventricular Tachycardia
• • Ventricular rhythm and rate are rapid and chaotic.
  • QRS complexes wide and irregular, no visible P waves

  Ventricular Fibrillation
• • No atrial or ventricular rate or rhythm.
  • No discernible P waves, QRS complexes, or T waves

  Asystole
• • main pacemaker
  • fastest firing rate (60–100 bpm)
  • best automaticity

  SA node
• • second highest firing rate (50 – 60 bpm)

  AV node
• Purkinje Fibers in the muscles have a firing rate of

  30 – 40 bpm
• Bundle branch fibers have a firing rate of

  40 – 50 bpm
• ventricular fibers fire at

  </=40 bpm
• Right bundle branch: contains how many fascicle/s

  1
• Left bundle branch contains how many fasicles

  two, anterior and posterior fascicles
• When is 15 lead ECG used

  Pediatrics
• 12 LEAD ECG SYSTEM

  3 Bipolar Leads (I, II, III)

  3 Modified Unipolar Leads (aVR, aVL, aVF)

  6 Precordial Leads (V1, V2, V3, V4, V5, V6)
• Additional Leads in 15 Lead ECG System


  V7, V8, V9, V3R, V4R, V7-V9
• Locations of additional leads in 15-lead ecg system

  V7

  5th intercostal space at posterior axillary line
• Locations of additional leads in 15-lead ecg system

  V8

  5th intercostal space at posterior scapular line
• Locations of additional leads in 15-lead ecg system

  V9

  5th intercostal space at left border of the spine
• Locations of additional leads in 15-lead ecg system

  V3R

  placed in mirror image position of V3 on the right side of the chest (halfway between V1 and V4R)
• Locations of additional leads in 15-lead ecg system

  V4R

  5th intercostal space at right midclavicular line
• Locations of additional leads in 15-lead ecg system

  V7-V9

  Taken in the same horizontal plane as V4
• Leads V3R and V4R are sensitive for

  right-sided myocardial infarctions
• Electrode locations posterior to V6 can be used to help detect

  acute posterior-lateral infarction
• Additional Leads in 15 Lead ECG System [Myocardial Wall]

  V1 to V2

  Septal
• Additional Leads in 15 Lead ECG System [Myocardial Wall]

  V3-V4

  Anterior
• Additional Leads in 15 Lead ECG System [Myocardial Wall]

  V5-V6

  Anterolateral
• Additional Leads in 15 Lead ECG System [Myocardial Wall]

  I, avL

  High lateral