How Is Heart Failure Diagnosed?
The heart is a mechanical pump, and as such, lends itself to measurement of its functional physiology. Diagnosis of heart failure begins with a history and physical exam to identify dyspnea, fatigue, and exercise intolerance, volume overload and edema, weight loss, or signs of inadequate perfusion (renal compromise).
Blood Tests in the Diagnosis of Heart Failure (HF)
- Kidney evaluation: Serum creatinine, which can indicate the reduction in glomerular filtration rate (GFR–the function of the kidney) seen in HF. Blood Urea Nitrogen (BUN) rises with HF. These parameters can be followed serially as a gauge for HF progression.
- Serum sodium: sodium depletion is due to neurohumoral changes of the body’s perceived decreased volume (from a paradoxical perspective of decreased ejection fraction).
- Serum albumin: the hypoalbuminemia from liver dysfunction and renal and GI losses will present as a low albumin level in the blood.
- Liver function tests and serum bilirubin evaluation: bilirubin can rise and liver function can decline in HF.
- Natriuretic peptide measurement: persistent elevations occur in HF.
Chest X-ray (CXR)
CXR can demonstrate volume overload as pulmonary edema, pleural effusions, and vascular congestion in the lung.
An ECG can demonstrate alterations in the normal wave patterns typically recorded in healthy individuals and how far they deviate from the normal. Although there is no ECG “marker” that is diagnostic for HF, wave abnormalities that indicate prior myocardial infarction or cardiomyopathy can reveal possible causes of HF or its comorbidities. Arrhythmias such as the atrial fibrillation or ventricular tachycardia that contribute to advanced HF can be identified for the purpose of driving therapy decisions.
Diagnosis of Advanced Heart Failure
Much of the diagnostic evaluation on HF patients, since there is a previously established diagnosis of HF, is to diagnose the transition to advanced heart failure, which is based on severity of symptoms and failure to remedy fluid retention or renal failure, along with advancing cardiac dysfunction. Such a transition into the “advanced” category worsens the prognosis and therefore calls for more aggressive surveillance and therapy:
- Blood tests for serum electrolytes (including sodium), blood count (CBC), renal function tests (BUN and creatinine), thyroid function tests, liver function tests (including serum albumin, bilirubin, and liver enzymes), and natriuretic peptide levels
- Chest X-ray to identify any pulmonary edema and rule out other causes for dyspnea (pneumonia, malignancy, etc.)
- Ultrasonography–a transthoracic echocardiogram (TTE) to evaluate ventricular and valve function and if inconclusive, a transesophageal echogram (TEE)
- Limited exercise testing, if feasible
- Right cardiac catheterization for those on mechanical circulatory support (left ventricular assistance devices–LVADs) or who have had cardiac transplantation