Occurs when the pacemaker site moves between SA node and an ectopic focus in the atria producing P-waves of varying size and shape.
| 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 |
- Chronic lung & valvular heart disease
- Increase vagal tone
- No specific symptoms
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.
| 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 |
- Anxiety
- Arial hypertrophy
- Coronary Artery disease
- Hyperthyroidism
- Stimulants
- Valvular Disease
- Palpation
- Skipped Beat
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 |
- Anxiety
- Arial hypertrophy
- Coronary Artery disease
- Hyperthyroidism
- Stimulants
- Valvular Disease
- Palpation
- Skipped Beat
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 |
- Anxiety
- CCF
- Stimulants
- Valvular or Coronary Artery Disease
- Hyperthyroidism
- Palpation
- Chest discomfort & pounding pulse
- Syncope
- Shortness of breath / Tiredness
- Excessive urine production
- Sweating
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) |
- Coronary Artery or Valvular Disease
- Hypertension
- Pulmonary Disease
- Post Cardiac Surgery
- Pulmonary Embolism
- Palpations
- Shortness of breath
- Anxiety
- Syncope
- Angina
- Weakness feeling
- Hypotension
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) |
- Atrial dilation
- Ischemic heart disease
- Myocarditis or Pericarditis
- Stress
- Smoking or alcohol
- Post cardiac surgery
- Pulmonary disease
- Heart palpations
- Irregular pulse (pounding/racing/fluttering
- Dizzy / Lightheaded
- Fainting
- Confusion
- Fatigue
- Difficulty breathing (especially when lying down)
- Chest tightness sensation
Page contributors:
 | Thanh Bui, AP60825 Event Medic, Emergency Medical Technician & Volunteer Development Officer
|
 | Andrew Moffat, AP16790 |
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