Fig. 3.
Number of procedures plotted against time. Light grey: PVA; Medium grey: AVA; Failed AVA (crossover group) are represented by the solid line. Number of failures decreases with time.
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.