What is the relationship between the P waves and the QRS complexes?
Remember that in the normal ECG every QRS complex is preceded by a P wave, and the time between the two forms is less than 0.20 second. Heart blocks are rhythms that are caused by altered conduction through the AV node. As conduction in the AV node shows, the interval between the P wave and the QRS complex lengthens. If slowing in the node becomes pronounced, some P waves will be blocked in the AV node. In the worst case, no P waves will pass through the AV node to excite the ventricles. *This link is provided for convenience only, and is not an endorsement or assurance of the entity or any product or service. This content is reviewed regularly. Last updated 11/24/08.
