Alternative definition : CDISC: A unipolar electrocardiogram lead site; the electrode is placed on the anterior
chest wall at the fourth intercostal space (between ribs 4 and 5) to the left of the
sternal border. In small animals it corresponds to V2-V3 where it is placed at the
6th left intercostal space near the sternum. In large animals it is placed over the
6th rib at the level of the costochondral junction on the left side of the thorax.;
Currated CISMeF NLP mapping