DIAGNOSIS OF HEART FAILURE
The diagnosis of heart failure is primarily made based on symptoms and backed by more precise diagnostic tests to either rule out similar disease processes or confirm a diagnosis of HF.
Health History
Taking a focused health history is an essential part of reaching a differential diagnosis of HF. This may include any medical or surgical history, list of medications taken, recent diagnostic test results, any concerning or pertinent symptoms (such as orthopnea, paroxysmal nocturnal dyspnea, weight gain, abdominal bloating, reduced appetite, and dyspnea-free activity), family cardiac history, and vital signs. It may be taken by a physician or an advanced practice nurse.
Physical Examination
A physical examination is performed to verify the subjective complaints of the patient and further determine a diagnosis of HF. Abnormal findings may support the diagnosis of HF.
Cardiovascular examination includes blood pressure, heart rate, pulses, and cardiac auscultation. Chest pain may occur from decreased coronary artery perfusion secondary to decreased cardiac output or coronary artery obstruction. The point of maximum impulse (PMI), which is the point furthest from the sternum where the cardiac impulse can be felt, may be displaced due to left ventricular hypertrophy.
Intake and output and daily weights are measured accurately using a consistent method to determine fluid balance or overload.
Inspection of the skin for edema or skin discoloration will show the presence of fluid retention. Copper-colored, shiny lower-leg and ankle discoloration accompanied by dry, flaky skin may indicate recurrence of swelling and reabsorption of fluid. Moderate or severe heart failure may produce visible shortness of breath. The skin may be pale, ashen, or cyanotic. Jugular veins may appear distended. The skin may be cold and clammy from vasoconstriction.
Palpation is used to determine the severity of peripheral edema and whether a depression (pitting) is produced that does not resolve immediately. The abdomen is palpated to establish hepato- or splenomegaly. Abdominal tenderness over the liver is indicative of hepatic congestion.
Auscultation of the heart and lungs may elicit adventitious breath sounds, such as crackles as in the case of pulmonary edema or pleural effusion caused by left-sided HF. S3 and S4 heart sounds or a cardiac murmur may be heard. Labored respirations may indicate hypoxia, pulmonary edema, pleural effusion, and hypervolemia.
Vital signs are usually checked every 1 to 8 hours during hospitalization based on the severity of the HF and checked with each physician or clinical visit, where the patients bring in a log of their blood pressures that they have taken themselves. Hypertension is common due to increased venous resistance (afterload) or hypervolemia from fluid retention. Tachycardia >100 beats per minute is often an early sign of HF as a compensatory mechanism for decreased cardiac output.
Cardiac monitoring may need to be performed continuously to assess for dysrhythmias. The respiratory rate may be elevated (>14 to 16 breaths per minute) due to pulmonary edema or decreased cardiac output as the body attempts to increase oxygen intake to compensate for hypoxia.
Hemodynamic monitoring when a patient is in the ICU may include continuous BP monitoring via an arterial line as well as cardiac output, pulmonary artery pressure, and pulmonary artery capillary wedge pressure via a pulmonary artery or Swan-Ganz catheter. Diuretic medications and ultrafiltration or aquapheresis (fluid removal) orders are based on these readings to remove excess sodium and fluid.
Oxygen saturation is decreased (<94%) in the presence of fluid in the lungs and may need to be monitored continuously, necessitating supplemental oxygen or positive pressure to be given (Harding et al., 2020).
Electrocardiogram
An electrocardiogram (ECG) is performed to determine the presence of any dysrhythmias, including an abnormal heart rate, since damage to the ventricular myocardium following an acute myocardial infarction may result in ventricular dysrhythmias. This can also be observed on the patient’s cardiac monitor atrial fibrillation. The ECG can also reveal evidence of myocardial ischemia indicating coronary artery disease as an indirect cause of HF. This may be performed by nurses, emergency room technicians, medical assistants, lab technicians, or ECG technicians.
Chest X-Ray
A chest X-ray may show cardiomegaly, which is common in protracted HF. It may also display abnormalities in the cardiac chambers, pulmonary congestion, displacement of the heart, and abnormalities of the lungs and greater blood vessels. This is performed by a radiology technologist. It may only be officially read by a physician, particularly a radiologist, or an advanced practice nurse.
Treadmill Stress Test
A treadmill stress test is performed to determine activity tolerance. It is used to diagnose coronary artery disease, cardiac valvular disease, and chronic HF. It is performed concurrently with ECG and BP monitoring by a physician or trained clinician. The testing is stopped if the patient experiences extreme hypertension, tachycardia, or chest pain (NIH, 2020). A treadmill stress test is preferable to assess activity tolerance, but a chemical stress test with nuclear imaging may be needed for those unable to physically walk or raise their heart rate to a target goal (Morgan, 2021).
Echocardiogram
An echocardiogram shows abnormalities of the valves, the size and structure of the heart and chambers, and the condition of the pericardial sac and the ascending aorta. The ejection fraction is also measured during an echocardiogram, signifying the strength of the myocardium as a pump. Therefore, an echocardiogram is crucial in determining whether the HF is systolic or diastolic. This is performed by a trained sonographer who uses conducting gel and a transducer to transmit information to a specialized computer via sound waves. It is evaluated by a cardiologist.
Cardiac Catherization
Cardiac catheterization (heart cath), or coronary angiography, is a highly invasive procedure in which a physician advances a thin, flexible catheter via the radial or femoral artery (for a left cardiac catheterization) and through the internal jugular, femoral, or subclavian veins (for a right cardiac catheterization) to obtain right-sided heart pressures. Dye is then injected into the arteries, and a radiologic video (cine) is taken to measure the degree of blockage in any of the coronary arteries. During this procedure, an angioplasty and stent placement may be performed. Each coronary artery will reveal the percentage of obstruction, guiding the need for and type of intervention. Coronary artery disease is one possible cause of heart failure (NIH, 2020).
Labwork
BNP (B-type natriuretic peptide) testing is the most definitive diagnostic test for HF. This biomarker establishes both the presence and severity of HF. BNP levels are also frequently rechecked to measure the success or failure of treatment. Normal range for BNP is <100 pg/ml. The higher the reading, the more severe the HF.
The neurohormone BNP is produced by myocardial cells. An increase in this hormone is caused by increased atrial or ventricular diastolic wall stretch to show the degree of left ventricular failure, as in HF. The BNP level may read as normal in heart failure in patients with HFpEF. Patients with acute decompensated HFpEf may have an elevated BNP (100–500 pg/ml), but lower than patients with HFrEF. Obesity sometimes causes decreased BNP production and increased BNP clearance, resulting in lower BP levels, sometimes to the point of normal (Yancy et al., 2017).
Other diagnostic labwork for heart failure includes:
- A complete blood count (CBC) will determine the presence of infection or anemia.
- A comprehensive metabolic panel (CMP) measures electrolytes, kidney function (BUN and creatinine), liver function, glucose, calcium, magnesium, and albumin.
- Urine sodium is measured to determine the possibility of sodium retention.
- Urine specific gravity measures urine concentration.
- Thyroid function is measured to rule out thyroid disease as a cause of HF, and for elderly patients and those with atrial fibrillation.
- Serum iron, ferritin, and TIBC are measured to distinguish the possible causes of anemia.
- Serum interleukin-6 is a cytokine that signals the presence of inflammation.
- C-reactive protein (CRP) is produced by the liver and is increased in the presence of inflammation.
- Tumor necrosis factor-a (TNF) is a cytokine that signals the presence of inflammation.
(Merck & Co, 2020)
| A widely accepted and long-established system of HF classification is the New York Heart Association (NYHA) functional classifications. It distinguishes different levels of heart failure severity according to the patient’s ability to perform certain physical activities. | |
| Class | Patient Ability |
|---|---|
| (Shoemaker et al., 2020; Sole et al., 2020) | |
| I | No physical limitations |
| II | Slight limitations; comfortable only at rest; minimum activity starts to produce the symptoms of HF |
| III | Marked limitations; comfortable only at rest; moderate activity produces HF symptoms |
| IV | Unable to perform any activity without symptoms of HF; symptoms while at rest |
| Stage | Description |
|---|---|
| (Shoemaker et al., 2020; Sole et al., 2020) | |
| A | At high risk of developing heart failure, but without structural heart disease or symptoms of HF (e.g., people with hypertension, coronary artery disease, diabetes, history of drug or alcohol abuse, rheumatic heart disease, or family history of cardiomyopathy) |
| B | Structural heart disease with or without symptoms of HF (e.g., left ventricular structural changes, heart valve disease, or a history of myocardial infarction) |
| C | Structural heart disease with prior or current symptoms of HF (e.g., shortness of breath, fatigue, or symptom-free and receiving treatment for prior symptoms) |
| D | Refractory or end-stage HF requiring specialized interventions such as cardiac transplantation or compassionate care such as hospice |
| * American College of Cardiology/American Heart Association | |