See brief interpretation of EKG strip above
– sinus node beats followed by a nearly 5 second pause seen as an isoelectric line
– no relationship between the preceding PP intervals and the pause
Sinus arrest is a transient pause in sinus node activity. Sinus arrest is recognized on the EKG as an isoelectric line of variable duration with no P waves or QRS complexes. The pause is usually followed by an AV-nodal escape beat or a new sinus node beat (as in the EKG above).
Sinus arrest may look like a sino-atrial (SA) block. In SA block the sinus activity is preserved, but the impulses are blocked resulting in missed P waves and QRS complexes. However, in SA block the pause seen on the EKG will represent a multiple (whole number) of the preceding P-P interval. This relationship is absent in sinus arrest.
Sinus arrest may be seen due to increased vagal tone, drug intoxication or sick sinus node syndrome.