The Lewis or S5 Lead
Christopher Watford has described the physiology and advantages of the Lewis lead extensively in his blog post, Highlighting Atrial Activity on an ECG: The S5 Lead, as well as via audio on the EMCrit Podcast with Scott Wiengart. References as follows:
High and Low Precordial Sequences
“High” and “Low” precordial leads have been utilized to visualize underrepresented regions of myocardium (such as the high lateral wall), as well as to better appreciate the typical 12-lead perspective when the heart is shifted up or down in the chest (as in emphesema). The Cardiophile blog describes this in greater detail.
ECG from a Brugada syndrome patient showing most severe ST–T abnormalities in leads overlying right ventricular outflow tract (shaded area): coved-type ST segment in second and third intercostal space (V2IC2 and V2IC3). Intermediate ST–T abnormalities (saddleback-type) arerecorded in fourth intercostal space (V2IC4). [Graphic and text – Meregalli, et al., 2005]
[Unknown image source.]
The three types of Brugada syndrome as seen on ECG. Image retrieved from http://reference.medscape.com/features/slideshow/complications-alcoholism.
[Image retrieved from Life In The Fast Lane: http://lifeinthefastlane.com/ecg-library/brugada-syndrome/]
Body Surface Mapping
Heartscape Technologies has a case library describing some of the benefits of this modality, as well as a diversity of educational resources associated with their product, The 80-Lead Prime ECG. Obviously this is not without conflict of interest, but their “occult STEMI” cases are quite interesting.
Highlighting Pacemaker Activity
Four lead placement variants used to better visualize pacemaker activity: