UNCONTROLLED WHEN PRINTED
Wandering Atrial Pacemaker

Occurs when the pacemaker site moves between SA node and an ectopic focus in the atria producing P-waves of varying size and shape.

1

QRS Complex P Wave PR Interval Rate (bpm)
0.08 – 0.10s (2 – 2.5 small boxes) Vary in shape, direction & size Slight Variation 60-100 bpm
Causes
  • Chronic lung & valvular heart disease
  • Increase vagal tone
Signs & Symptoms
  • No specific symptoms
Premature Atrial Contraction (PAC)

Premature ectopic foci discharge in the atria causing abnormal P-waves as impulse wasn’t from SA node. Ventricular conduction is normal, hence normal QRS complex. The SA node generally takes over after a PAC event therefore there may be a pause.

2

QRS Complex P Wave PR Interval Rate (bpm)
0.08 – 0.10s (2 – 2.5 small boxes) Premature & abnormal size/shape 0.12 – 0.20s (3 – 5 small boxes) Varying
Causes
  • Anxiety
  • Arial hypertrophy
  • Coronary Artery disease
  • Hyperthyroidism
  • Stimulants
  • Valvular Disease
Signs & Symptoms
  • Palpation
  • Skipped Beat
Non-conducting Premature Atrial Contraction (NCPAC)

3

When the ectopic foci in the atria discharges an impulse during refractory phase – The impulse cannot pass through AV node resulting in only a P-wave.

QRS Complex P Wave PR Interval Rate (bpm)
Absent after NCPAC Premature & abnormal size/shape Absent after NCPAC Varying
Causes
  • Anxiety
  • Arial hypertrophy
  • Coronary Artery disease
  • Hyperthyroidism
  • Stimulants
  • Valvular Disease
Signs & Symptoms
  • Palpation
  • Skipped Beat
Supraventricular Tachycardia (SVT) / Paroxysmal Atrial Tachycardia (PAT)

4

Arrythmia that does not originate from SA node – It is very fast rate due to the ectopic site and AV node creating an accessory pathway resulting in impulses travelling in circular motion throughout the atria at an accelerated rate.

QRS Complex P Wave PR Interval Rate (bpm)
0.08 – 0.10s (2 – 2.5 small boxes) Abnormal (hidden within T-wave) Not measurable 140 – 160 bpm
Causes
  • Anxiety
  • CCF
  • Stimulants
  • Valvular or Coronary Artery Disease
  • Hyperthyroidism
Signs & Symptoms
  • Palpation
  • Chest discomfort & pounding pulse
  • Syncope
  • Shortness of breath / Tiredness
  • Excessive urine production
  • Sweating
Atrial Flutter

5

When ectopic sites fire rapidly, and the SA node has lost control of pacemaking. This results in a fast-atrial rate – The AV node tries to control the impulses too, creating a variety of atrial-to-ventricle ratio. Causes reduction in cardiac output

QRS Complex P Wave PR Interval Rate (bpm)
0.08 – 0.10s (2 – 2.5 small boxes)
May not occur with every flutter wave
Sawtooth Flutter Waves Absent 300-400 bpm (Atrial)
Causes
  • Coronary Artery or Valvular Disease
  • Hypertension
  • Pulmonary Disease
  • Post Cardiac Surgery
  • Pulmonary Embolism
Signs & Symptoms
  • Palpations
  • Shortness of breath
  • Anxiety
  • Syncope
  • Angina
  • Weakness feeling
  • Hypotension
Atrial Fibrillation (AF)
6
7

When multiple ectopic sites fire rapidly, and the SA node has lost control of pacemaking. This results in a fast-atrial rate – Up to 600 impulses reach the AV node from various sites. Reduces cardiac output and high risk of thrombus formation after 24-48hrs of AF.

QRS Complex P Wave PR Interval Rate (bpm)
0.08 – 0.10s (2 – 2.5 small boxes) Wavy baseline Absent >400 bpm (Atrial)
Causes
  • Atrial dilation
  • Ischemic heart disease
  • Myocarditis or Pericarditis
  • Stress
  • Smoking or alcohol
  • Post cardiac surgery
  • Pulmonary disease
Signs & Symptoms
  • Heart palpations
  • Irregular pulse (pounding/racing/fluttering
  • Dizzy / Lightheaded
  • Fainting
  • Confusion
  • Fatigue
  • Difficulty breathing (especially when lying down)
  • Chest tightness sensation

References

College of Pre-Hospital Care. (2015). 12-Lead ECG Analysis: Self-Directed Learning Package. Version 3. St John Ambulance Ltd.  

Curtis, K., & Ramsden, C. (2016). Emergency and trauma care for Nurses and Paramedics (2nd ed.). Elsevier Australia.

DeLaune, S. C., Ladner, P. K., McTier, L., Tollefson, J., & Lawrence, J. (2016). Australian and New Zealand fundamentals of nursing (1st ed.). Cengage Learning Australia Pty Limited.

ECG & ECHO Learning. (2020). Clinical ECG Interpretation. https://ecgwaves.com/topic/ecg-normal-p-wave-qrs-complex-st-segment-t-wave-j-point/

Life in the Fast Lane. (2020). ECG Library. https://litfl.com/ecg-library/

St John WA Ltd. (2017). Electrocardiography (ECG). Clinical Resources. https://clinical.stjohnwa.com.au/clinical-skills/assessment/vital-signs/electrocardiography-(ecg)

WikiEM. 2020. The Global Emergency Medicine Wiki. https://www.wikem.org


Page contributors:

60825Thanh Bui, AP60825
Event Medic, Emergency Medical Technician &
Volunteer Development Officer

 

16790

Andrew Moffat, AP16790
Volunteer Training Manager & Volunteer Development Officer

Want to help improve this article? Visit our Contribute page.

St John Ambulance Western Australia Ltd © Copyright 2020, All Rights Reserved

Privacy Policy | Copyright Statement & Disclaimer