Cardiac Dysrhythmias Advanced

What is the pacemaker of the heart normally? - Answer- SA Node. Where does the SA node originate? - Answer- Upper right atrium. What is the pathway of conduction in the heart? - Answer- SA node - atria - AV node - bundle of his - bundle branches - purkinje fibers - ventricles. What does stimulation of the vagus nerve cause? - Answer- Decreased firing of the SA node and slowed impulse conduction of the AV node. What does stimulation of the sympathetic nerves cause? - Answer- Increased firing of the SA node and increased impulse through the AV node, and cardiac contractility. What does the P wave represent? - Answer- Time for the passage of the electrical impulse through the atrium causing atrial depolarization (contraction). What is the normal P wave duration? - Answer- 0.06 - 0.12. What is a possible variation cause of a P wave? - Answer- Disturbance in conduction within the atria. What does the PR interval represent? - Answer- The measure from the beginning of the P wave to the beginning of the QRS complex, represents time taken for impulse to spread through the atria, AV node, and bundle of his, the bundle branches and purkinje fibers, to a point of immediately preceding ventricular contraction. What is the normal PR interval? - Answer- 0.12 - 0.20. What is a possible variation cause with PR interval? - Answer- Disturbance in conduction usually in the AV node, bundle of his, or bundle branches but can be atria as well. What does the QRS interval represent? - Answer- Measure from beginning to end of QRS complex, represent time taken for depolarization (contraction) of both ventricles (systole). What