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Junctional Rhythms Junctional Bradycardia (Example) Accelerated Junctional Rhythm (Example 1) Accelerated Junctional Rhythm (Example 2) Junctional Tachycardia (Example) A junction rhythm originates at or below the AV node and occurs when the sinus node fails to create the pacemaker activity of the heart, thus the AV node takes over this function. The QRS complex is narrow since conduction still occurs within the normal ventricular conduction pathway. The P waves (indicating atrial depolarization) would be inverted (or at least different than the sinus P wave) since the atrium are activated in the opposite direction than normal, however since the P wave in a junctional rhythm would occur at almost exactly the same time as the QRS complex (since the action potential which starts at the AV node travels up to the atrium AND down to the ventricles at the same time), the P wave may occur just barely before the QRS complex (short PR interval), during the QRS complex (so you would not see the P wave at all), or just after the QRS complex. The rhythm is called "accellerated" when the heart rate is above 60 since the AV node's intrinsic pacemaker rate is about 40-60 beats per minute. |
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