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C

The ECG displayed shows sinus bradycardia with hyperacute ST segment elevation in the inferior limb leads, and to a lesser extent in leads V6 and V5. There is reciprocal ST segment depression in the anterior chest leads (V1 to V3). These findings are consistent with acute occlusion of a large dominant right coronary artery that supplies branches to the inferior LV wall (posterior descending artery) and to the inferolateral to lateral surface of the LV, giving rise to a large acute inferior MI (STEMI).

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E

The ECG displayed shows a narrow complex irregular rhythm, and no two R-R intervals in the lead II rhythm strip at the bottom of the image are the same (hence the term "irregularly irregular" that is often used of atrial fibrillation). Inspection of leads III and V1, in particular, shows that the atrial activity is very disorganised and irregular. P waves are not seen in atrial fibrillation; instead there are irregular fibrillatory waves at a rate of 400 to 600 per minute, only a proportion of which are conducted to the ventricles, to produce a rapid irregular ventricular rate (in the presence of normal AV conduction).