AVNRT occurs when a reentrant circuit is present within the AV node itself. In this situation, there are two separate conduction pathways within the AV node instead of just one (present in about 5 ...

Note the premature ventricular contraction (PVC) that triggers the AVNRT in this ECG. If a premature atrial contraction (PAC) or premature ventricular contraction (PVC) occurs at the right time ...