Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
(A) This is V1 lead of a healthy patient with normal left atrial size by echocardiography. V1 electrode placed in normal location (4th ICS) (A), 3rd ICS (B), and in 2nd ICS (C). It is clear that the normal P wave in the 4th ICS becomes progressively more negative (B and C) as the electrode of V1 is placed in higher ICS.
ICS, intercostal space
