Photo: Human heart, anterior view, artificial valve, coronary bypass. Illustration by Patrick J. Lynch. Source: Flickr, free to use under Creative Commons Attribution 2.5 License (https://creativecommons.org/licenses/by/2.5/).
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.