As you know, standard ECG (the left-sided one) is not so useful in diagnosing the RIGHT VENTRICULAR INFARCTION.
For this purpose, RIGHT-SIDED ECG is used.
V1 is the only lead on the standard ECG that reflects changes in the right ventricle.
That's why recordings from leads placed on the right side of the chest are much more sensitive and specific in detecting the changes of right ventricular infarction.
The right-sided precordial electrodes are placed across the right side of the chest in a mirror image of the standard left-sided leads and are labeled V1R to V6R (RV1 to RV6 is another commonly used nomenclature for this lead distribution).
You may use either the entire right-sided leads V1R to V6R or the single lead V4R.
Lead V4R(or RV4 but NOT V4) is placed in the right 5th intercostal space at the mid-clavicular line.
V4R is the most useful lead for detecting STE associated with right ventricular infarction and may be used solely in the evaluation of the possible right ventricular infarction.