Arterial segment	Arterial branch	Perfused region	ECG effects of ischemia
Proximal segment	SA nodal branch	SA node	Sinus bradycardia
	Right atrial branch	Atrial free wall	Atrial infarct pattern, atrial fibrillation
Middle segment	Lateral RV branches	Lateral RV free wall	ST segment elevation; later, abnormal Q waves in leads V3R through V6R
	Marginal RV branch	Inferior (posterior) RV free wall
Distal segment	AV nodal branch	AV node	AV block
Posterior descending segment	Posterior lateral LV branches Posterior descending artery	Posterior left ventricle Inferior septum, inferior LV free wall	ST segment elevation; later, abnormal Q waves in leads II, III and aVF