This ECG shows a classic inferior - posterior STEMI. This M.I. was due to complete occlusion of the right coronary artery. ST elevation apparent in Leads II, III, and aVF show the acute injury in the inferior wall, while ST depressions in V1 and V2 are reciprocal of the ST elevations in the posterior wall. The tall R waves in Leads V1 - V3 most likely are reciprocal to pathological Q waves in the posterior wall. Tall R waves in the right precordial leads can be caused by other cardiac conditions, such as right ventricular enlargement. RV hypertrophy can probably be ruled out in this case because there is no right axis deviation or P pulmonale. Because inferior wall M.I.s often extend into the posterior wall, it is the most likely cause of the tall R waves.
Posterior Wall M.I.
These two ECGs are from a 57 year old man with chest pain. The initial ECG shows ST elevation in Leads II, III, and aVF - inferior wall STEMI. Reciprocal changes are as expected in I and aVL. Reciprocal ST depression also seen in V1 and V2 indicate probable posterior wall involvement. Not surprising since the inferior wall is simply the lower part of the posterior wall. The first ECG also shows the patient in sinus brady with junctional escape: AV dissociation. The sinus node is often affected in IWMI that is caused by right coronary artery occlusion. The second ECG shows a slight increase in the sinus rate, and a sinus bradycardia. A V4 right lead has been performed, clearly showing ST elevation, and indicating right ventricular M.I.
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