Heart Failure Support Group
Heart failure is a condition that can result from any structural or functional cardiac disorder that impairs the ability of the heart to fill with or pump a sufficient amount of blood throughout the body. It is often undiagnosed due to a lack of a universally agreed definition and difficulties in diagnosis, particularly when the condition is considered "mild."
Jesus
An echocardiogram should show if CHF is a factor, but maybe they wouldn't do that unless there is more indication of it.
Be sure to include all symptoms when talking to the doctor.