1. Heart Failure -- National Library of Medicine
Cardiac Resynchronization Therapy Procedure for Congestive Heart Failure. Heart Failure in Children and Adolescents (American Heart Association). Potassium Guidelines for Patients with Heart Failure (Cleveland Clinic Foundation).
http://www.nlm.nih.gov/medlineplus/heartfailure.html

2. Heart Failure -- Information from Healthwise
Echocardiogram can also be used to check whether your heart failure is getting worse by measuring how much blood your heart pumps to your body from the left lower chamber ( left ventricle ). Combining a two-chamber (biventricular) pacemaker and...
http://www.everettclinic.com/kbase/topic/special/hw44415/sec1.htm

3. Heart failure -- Mayo Clinic
Heart failure, also known as congestive heart failure, means your heart can't pump enough blood to meet your body's needs. Heart failure means your heart can t efficiently pump blood throughout your body.
http://www.mayoclinic.com/invoke.cfm?objectid=ED8BB6BC-745C-42AA-B1A61E5947AA80...