1. Chapter 2 - ECG Supraventricular Rythms Early beats arising from above the ventricles. PAC, PJC

3. Normal Sinus Rhythm Sinus Arrythmia Irregular rhythm (R-R). Can be caused by respiration. HR increases with inspiration (vagal nerve depressed) and decreases with expiration (vagal nerve stimulated). Phasic SA – due to respirations vs. Non-phasic SA not due to respirations

4. Normal Sinus Rythm A. Figure 2.4, page 21. Sinus Tachycardia and SA Nodal Re-Entrant Tachycardia If obtained under resting conditions this would be considered: “SA Nodal Re-Entrant Tachycardia” (pg. 23). Occurs suddenly with abrupt termination, but slower than SVT with only a rate of 120-150. Depolarizing “spins” around the SA node, circling repeatedly causing a high heart rate at rest.

5. Sinus Bradycardia cause: fitness, meds, disease In this example, the heart rate is 34 beats · min –1.

6. Sinus Pauses – Difficult to know why “ a delay occuring before the appearance of a P wave” Failure of SA Node to depolarize – Note: after pause rhythm resumes with a “P” wave that is normal with a normal QRS. SA Block – depolarization does not “escape” from the SA Node – Note: Rhythm resumes with a normal QRS.

7. Sinus Pause

8. PAC – premature, ectopic beat arising somewhere other than the SA Node. Arises in atria or AV node. P wave morphology is different. PR interval will differ (shorter) due to change in time for conduction to move to ventricles. QRS is normal. Blocked or non-conducted PAC. AV node is still in the refractory period. *= ectopic focus

9. Junctional Premature Complex or PJC Premature beats w/- or absent P waves due to origin at or near the AV Node Sometime difficult to decide origin so both terms will work.