Diagnosing Heart Failure

  • Your health care team may need to do some tests to see how the heart is working, to find out the cause of heart failure (HF), and to see if you have other problems that may make HF worse.You may feel better by treating all found problems.
  • Knowing all about your HF will allow for the right treatments to begin. Starting the right treatment quickly may help improve your heart function.
  • There are many tests that can be done to assess your heart function. The type of test will depend on what your doctor is looking for. One of the things they need to know is how much the heart is squeezing with each beat. This is called the "ejection fraction" or EF. A normal EF is 55-70%- meaning that about 55% of the blood is squeezed out of the left side of the heart with each heartbeat. An EF less than 45% indicates that you have "systolic" heart failure. This means that your heart is weak and can't pump very well. Some people have heart failure when their heart squeezes a normal amount but does not rest between beats. This is called "diastolic" heart failure. This occurs when the heart is stiff, with thick walls, and isn't able to handle fluid changes in the heart. Tests which help your health care team learn about your heart function include:
    • Echocardiogram :
      Echocardiogram (Echo) is the best way to get a picture of the heart using ultrasound- or sound waves. An echo can tell the EF, the heart's size, the thickness of the walls, and heart valve function. Echos can also detect blood clots, abnormal growths, or holes between the chambers. This test is often done to help detect heart failure, and is done every so often to monitor the heart's response to treatment. Echos are painless and safe.
    • Other tests that can assess the heart's squeezing function, that provide an EF- include:
      • Ventriculogram: This is part of a heart catheterization (cath), or angiogram, when dye is given into the heart to show the heart's EF through moving X-ray pictures. This is done in the cath lab, where a hollow tube is placed into the large vessel in the groin that leads to the heart.
      • Cardiac magnetic resonance (CMR): This is an MRI of the heart, using fields of magnets to create pictures of the heart.
      • Multi gated acquisition scan (MUGA): A MUGA scan is a test done to assess the EF, of both the right and left sides of the heart. Special medicine is given into the blood that is followed as it moves through the heart. The images show the squeezing function.
      • Other nuclear medicine tests: There are many types of stress tests, which are done to see if there is a blockage of the heart vessels called coronary artery disease. During this test, a special medicine helps create pictures that measure the EF.
      • Positron Emision tomography (PET).

        A PET scan is a nuclear imaging study that shows changes and functions of organs at the cellular level. This scan is helpful with certain heart problems. A PET scan uses a special medicine given into the vein.

        This medication tags to the tissues and organs. A special scanner records the energy produced by the cells. A computer converts the recording into three-dimensional pictures of an area of the body and any cells that are changing show up at a brighter contrast to any surrounding normal cells.

  • Your doctor looks at your heart rhythm to check the electrical function of your heart. The heart's pumping depends on its electrical function. Many heart failure patients have heart rhythm problems, or "arrhythmias". Weak or enlarged heart muscles may have more rhythm problems in both the top and bottom chambers of the heart. Knowing about these heart rhythm problems helps prevent worse problems like fainting or even death .
    • Electrocardiogram (ECG) :
      This is an easy test to assess the heart rhythm. The ECG is done using patches that are placed on the skin, to give an electrical image over six seconds. The ECG tells your doctor the heart rate, the heart rhythm, and can help show the thickness of the heart, and delays along the normal path electricity takes in your heart. The ECG is a quick and easy test that can also show if there is not enough blood feeding your heart, a sign of a heart attack.
    • Other tests to assess the heart rhythm may be done over longer time frames, to show the heart rate and rhythm. A Holter monitor is like an ECG, but a few of the patches are left on with a small box worn in a fanny pack, to measure the heart's rhythm for 24-48 hours. For patients who have heart fluttering, or "palpitations", an event monitor may be used. This type of heart box may be worn for up to a month. If you are wearing this type of monitor you can push a button to record your heart rhythm if you have symptoms of fluttering or palpitations. This is very helpful if the symptom happens infrequently. The recording can then be transmitted over a phone line. Telemetry is another type of heart monitor where a small box is worn while in the hospital. This allows the nurses and doctors to watch your heart rate and rhythm during your stay.
  • Stress testing: The purpose of a stress test is to stress the heart, either with exercise or medications to see if there are blocked heart vessels. Blood pressure, symptoms and the ECG are watched closely during stress tests. Pictures are taken of the heart before, during and after the stress portion, to see how the heart pumps at rest and with stress. Some types of stress testing include:
    • Stress treadmill:
      A treadmill is used used to increase your heart rate. It starts slowly and the rate and incline is gradually increased to make your heart work harder. The EKG is watched during this test to see if exercise causes changes from a lack of bloodflow to the heart muscle.
    • Stress echo- this test uses an echo (above) that is done on the heart at rest, and then during exercise or when medicines are given to "stress" the heart.
    • Nuclear stress- As part of this test, the nuclear medicine or "tracer" is given that shows heart pumping at rest and after the stress.
    • Stress CMR- this is like the nuclear stress test, but uses magnetic resonance imaging (MRI).
  • Angiograms are tests done in the cath lab to see if there is blockage of the arteries that are on the outside of the heart, and if so, to what degree. Special lines are placed into the large vessels in the groin that lead right to the heart. Dye is given into this line and pictures of your heart are shown on a TV screen that shows the blood flow through the heart vessels . If there are blocked heart vessels, treating them can often improve the heart function of people with HF.
  • Right heart cath: A right heart catheterization (cath) is a test usually done in the hospital's cardiac catheterization lab (but sometimes may be done in the intensive care unit), where a special line is placed in a vein in the neck, leading into the right side of the heart. This line is placed to measure the pressures in the right side of the heart, the vessels that lead to the lungs, and some measures of the left side of the heart.

    Sometimes medications are given during the right heart cath to see how the heart responds such as medications to dilate or relax the blood vessels in the heart and lungs.

  • The VO2 test is an exercise test, using a bike or treadmill, to see how well the heart is getting needed oxygen to the muscles. Elite athletes measure their VO2 to see their degree of fitness. In HF patients, this test helps to decide if the feeling tired or fatigued is due to problems with the heart.
  • Symptoms such as shortness of breath and a cough are due to problems with the lungs or because of heart failure . Knowing the cause helps decide the best treatment. Common tests done to help decide this include:
    • Chest X-ray (CXR):
      Chest X-ray is a common test that takes a picture of the chest that can show if there is an infection (pneumonia) or extra fluid in the lungs. The CXR also shows the size of the heart, and the bones and structures of the chest.
    • Oximetry- a probe is placed on your finger (or ear) that uses light waves to measure the extra oxygen in the blood. Low levels of oxygen in the blood may help your doctor decide that you need to receive extra amounts.
    • Pulmonary function test (PFTs) - may be done to see if shortness of breath is caused by lung disease, such as asthma or chronic obstructive pulmonary disease (COPD), or emphysema.
    • Polysomnography (sleep study) - over recent years, we have learned that HF patients are at risk for "sleep apnea". Sleep apnea may make your HF worse. We can treat sleep apnea with special masks that provide oxygen while you sleep.
  • Blood (lab) tests:
    • Most blood tests are done to find out the cause and extent of heart failure, to check your response to medicines, and to find other problems that people with heart failure may have.
      1. B-type natriuetic peptide (BNP)- is one of the newest blood tests used in persons with heart failure . High levels suggest release of this hormone when the heart is stretched from too much fluid. Very high levels may mean severe heart failure. How to best measure and use BNP is now being studied.
      2. Thyroid function tests- are done to see if there are problems with the thyroid gland, which controls many of the body's functions, such as heart rate, temperature, maintaining body weight, and more. Some heart failure is caused by an under- or over- active thyroid, so problems need to be treated.
      3. Complete blood count- tells about the number of red and white blood cells, and other blood counts. This test is done to see if your blood count is low and might be causing shortness of breath. Low blood count is a common problem in patients with heart failure.
      4. Metabolic panel- tells your doctor about your kidney function, electrolytes and minerals in the body. These levels should be kept in a certain range. The kidney function may be low in heart failure patients because the heart is not pumping blood as strongly as it should. It can also be lowered because of some of the medicines you need to take. Some electrolytes in your body may be lost in the urine by taking water pills or "diuretics". These need to be closely watched and you may need to take extra pills to replace them.
      5. Lipid panel- high blood lipids can cause blockages in the heart vessels. Keeping lipid levels low may prevent a heart attack.
      6. Others blood tests: HIV can cause heart failure although it is an uncommon cause. Another rare disorder in which iron collects in your heart and liver can cause heart failure. Your doctor may recommend testing for these causes in some cases.
      7. Other tests: Urinalysis- may be done to see if there are other problems such as leaking proteins that may be found in persons with high blood sugar.