ECG lead V1

Lead placement: right 4th intercostal space in the parasternal space. Normally an S wave (downward deflection) in V1 from LV free wall depolarization. Septal R wave in V1 (if present) 25 msec. Q-wave not abnormal in V1. Causes of R in V1: 1) right bundle branch block - prolonged QRS 2) posterior myocardial infarction a) generally occurs in association with inferior wall MI b) Q's in II, III, aVF from inferior wall MI 3) Wolf Parkinson White (WPW) type A (accessory tract anterior to mitral valve) 4) right ventricular hypertrophy

References

Practial ECG Interpretation, Basic Electrocardiography & Cardiac Arrhythmias, T. Evans, M.D., UCSF, Ring Montain Press, 1998