Congestive heart failure is a collection of conclusions, so there is no single test that determines whether an individual has the syndrome. A number of tests are generally performed before a diagnosis is made. These include: an electrocardiogram (EKG) which may show causes of irregular heart rhythm; chest x-ray, showing an enlarged heart and/or fluid on the lungs; and an echocardiogram which can reveal the strength of the heart muscle, the size of the chambers, and valvular problems. Other tests used to determine presence of congestive heart failure are radionuclide ventriculogram (RVG) and cardiac catheterization.