Investigations leading to the diagnosis of Cardiac Heart Failure (CHF)

CHF is a grouping of clinical findings rather than a specific diagnosis or a single disease. CHF can be considered a symptom of impairment of the pumping action of the heart that is caused by an underlying disease.

The diagnosis of CHF is based on knowledge of the patient's pertinent medical history, a careful physical examination, and selected laboratory tests. These investigations are carried out to find evidence of cardiac dysfunction and to establish the underlying cause of heart failure.

A thorough patient history may disclose the presence of one or more of the symptoms of CHF (e.g. dyspnoea, orthopnoea, paroxysmal nocturnal dyspnoea, fatigue). In addition, a history of significant coronary artery disease, myocardial infarction, hypertension, diabetes, or significant alcohol use can be clues.

The physical examination is focused on detecting the presence of extra fluid i.e. oedema in the body. Pulmonary oedema can be detected by listening to the breathing sounds of the lungs (crackles and wheezes), and central cyanosis (bluish discoloration of the lips). Peripheral oedema is marked by swelling in the ankle or leg and peripheral cyanosis (bluish discoloration of the extremities). Jugular venous pressure is also checked to detect for any abnormal elevation. The heart is also examined (heart size – estimated with the position of the apical impulse, pulse, heart sounds, and murmurs). In addition, blood pressure is also measured to check for hypotension that maybe due to decreased cardiac output.

The first few diagnostic tests to order for a patient with suspected CHF include the electrocardiogram (ECG) and chest x-ray to explore the possibility of previous myocardial infarctions, arrhythmia, heart enlargement, and fluid in and around the lungs.

Blood tests are used to evaluate kidney and thyroid function as well as to check cholesterol levels, cardiac enzymes and the presence of anemia. Anemia is a blood condition that occurs when there is not enough hemoglobin (the substance in red blood cells that enables the blood to transport oxygen through the body) in a person's blood.

B-type Natriuretic Peptide (BNP) blood test. BNP is a substance secreted from the ventricles in response to changes in blood pressure that occur when heart failure worsens. BNP blood levels increases when heart failure symptoms worsen, and decreases when the heart failure condition is stable. The BNP level in a person with heart failure -- even someone whose condition is stable -- is higher than in a person with normal heart function.

Echocardiogram uses ultrasound to image the heart muscle, valvular structures, and blood flow patterns. The echocardiogram is very helpful in diagnosing heart muscle weakness. In addition, the test can suggest possible causes for the heart muscle weakness (e.g., prior heart attack, severe valvular abnormalities). Virtually all patients in whom the diagnosis of CHF is suspected should ideally undergo echocardiography at some point.

Cardiac catheterization: The arteries to the heart are visualized with coronary angiography (using dye inside of the blood vessels that can be seen using x-ray methods). During catheterization the pressures in and around the heart can be measured and the heart's performance assessed.

Other diagnostic tests include:
Nuclear medicine studies (radionuclide angiography)
Cardiac Biopsy: In rare cases (e.g. amyloidosis - an infiltrative disease)
Cardiac MRI: Only used if other tests do not provide satisfactory diagnosis.

The choice of tests depends on each patient's case and is based on the suspected diagnoses.

Contributed by John Lee