ECG Quiz

ECG Quiz

What is the rhythm?
a) Sinus rhythm
b) Low atrial rhythm
c) Idioventricular rhythm
d) None of the above
Answer: b) Low atrial rhythm
ECG showing negative P waves in inferior leads – II, III and aVF. A superior P wave axis means that the atrial activation is proceeding from below upwards. This occurs when the focus is in the low atrium – low atrial rhythm or coronary sinus rhythm. Low atrial rhythm can occur in sinus venosus ASD as the region of the sinus node is defective and an ectopic atrial focus takes over.

In addition the ECG also shows an intraventricular conduction defect in the form of notched R wave in leads II and aVF and an rSR’ pattern in lead III. Sometimes this pattern occurs in atrial septal defect and it is known as crochetage sign. The QRS width seems to be a little more than that in usual crochetage sign.