18 leads electrode cardiogram

hi , guys .,, is there any one knows how to do the 18 leads electrode cardiogram ? where the leads should be connect ?
Thanks !

have a great day !
In addition to the 12 lead EKG placement V4R right midclavicular line in the 5th intercostal space (V3 lead)V5R right anterior axillary line from V4R (use V2 lead)V6R right midaxillary line straight line from V5R (use V1 lead)V7 left posterior axillary line, straight line from V6 (use V4 lead)V8 left midscapular line straight line from V7 (use V5 lead)V9 left paraspinal line straight line from V8 (use V6 lead)

If you are lazy, simply obtaining a V4R is about 90% sensitive and specific regarding the identification of a RVI.