Nuclear LEXISCAN™ Stress Test?

WHAT IS A NUCLEAR LEXISCAN™ STRESS TEST?  Or  “Sit Down Stress Test”

A Nuclear Sit Down Stress Test or Lexiscan stress test, or LEXI, is designed to evaluate the condition of your coronary arteries.  These are the arteries that supply the heart itself with blood. This type of stress test is given when the Cardiologist feels that you may not be able to walk to an appropriate level of exercise on a treadmill.  This may be due to: arthritis, poor conditioning, the use of certain blood pressure medications that prevent your heart rate from increasing with exercise,  or the use of devices like a pacemaker of defibrillator.

Using a special type of imager, a small amount of radioactive tracer is injected into your blood before and after an injection of a medication called Lexiscan, and pictures are taken of your heart muscle.  Lexiscan replaces the physical act of exercise, and elicits the same response from your body that would occur if you were actually exercising. The pictures that are taken before and after the Lexiscan injection are then compared to each other, to see if there are any differences. Such differences in the pictures helps your cardiologist determine whether there are may be any major blockages in your arteries.  They can also see if there has been damage to the heart muscle after a heart attack.  It will also help them determine the best type of treatment you may need to correct any abnormal finding. Treatment options may include medications, dietary and lifestyle modification, or perhaps a cardiac procedure such as an angioplasty or coronary artery bypass surgery.

There are different reasons why your cardiologist may want you to have a LEXI and these may include:

  • symptoms or signs suggestive of coronary artery disease (CAD) such as chest pain, shortness of breath
  • significant risk factors for CAD such as smoking, high blood pressure, high cholesterol
  • assessment of your condition after a cardiac procedure such as bypass surgery or coronary angioplasty
  • clearance for certain surgeries that are determined to be of intermediate to high risk

Who will be performing my test?

  • An imaging technologist with special training in the use of radioactive drugs (Nuclear Medicine Technologist) will be taking the images of your heart using a machine called a Gamma Camera.
  • The Stress test will be supervised by a Hamilton Cardiology Nurse, Nurse Practitioner or Physician’s assistant. A Cardiologist is immediately available at all times in case of any medical emergency.
     

Is there any kind of preparations or instructions that I need to follow?

Please refer to the full instruction sheet that you were given at checkout or visit the website at www.hcahamilton.com, but general instructions are as follows.

  • No caffeine of any kind after 8pm the night before your test.  This includes chocolate, coffee, tea and sodas including decaffeinated beverages, since these include a small amount of caffeine.  Certain migraine medicines and cough syrups may contain caffeine so please refer to the package inserts or ask your pharmacist before taking any of these medications.
  •  Certain medications may interfere with the procedure and should be discontinued for at least 24hrs prior to testing:  TheoDur, Theo24, Theophylline, Aggrenox, Persantine, Slobid Aminophylline, Slobid, Uniphyl, Trental or Pentoxifylline.
  • For our male patients: The use of the following meds must be discontinued 24 hours prior to testing: Levitra or Viagra.  Cialis must be stopped 4 days prior to testing.
  •  For our female patients: To ensure that the breast is in the same position on both sets of images please wear a bra the day of your test if possible. An underwire bra is permissible.
  • You may use deodorant but please do not use any sort of body lotion or powder the day of your test. It is very difficult to get the EKG pads to adhere to your skin if it is too oily
  • Due to equipment requirements the imaging area is kept at approximately 68 – 72 degrees (F).  Please bring a sweatshirt or blanket if you are uncomfortable in a slightly cold environment.

What can I expect?
Check In: Prep and Resting Imaging

  • Once you have checked in you will be given a consent form to read and to sign.  If you have any questions about the testing, please feel free to ask for assistance.
  • You will then be taken into the prep area by one of our Nuclear Medicine Technologists.  They will verify information from your record and explain the procedure to you.
  • An intravenous line (IV Line) will also need to be placed into a vein in your arm or hand.  This is used to administer the radioactive drug used for imaging.  It is required for this procedure or we will not be able to take the pictures of your heart.
  • You will be asked to lift your shirt or blouse and electrocardiograph (ECG) stickers (heart monitoring stickers) will be placed on your chest. These electrodes are attached to cables which link to an ECG machine.  These will be used to constantly monitor your heart during the stress test portion.
  • The first dosage of the radioactive tracer (Cardiolite) will be administered.  This allows the cardiologist to see what your heart normally looks like.  This will be compared to the later images to see if any changes have occurred.
  • You will be asked to return to the waiting room and to drink about 12 to 16 oz of liquid. There is a water cooler in the hallway for your use.  There is also a refrigerator on the counter near the exit door that contains diet and regular non caffeinated soda.  You may drink one of these instead of water. Please use the rest room at any time.
  • To allow for the proper imaging a 45 to 60 minute wait is required before imaging can be started. You will be called back to the imaging area when it is time for your pictures.
  • Imaging is accomplished using a special type of radiation detector called a gamma camera.  This detects the injected tracer in the heart muscle and transfers it to a computer.  The computer processes these images into thin slices so that the doctor can look at blood flow into your heart muscle.
  •  You will sit on the imaging chair and bring your arms over your head.  It is very important that at least the left arm be raised above the head. If it is by your side it may prevent some of the tracer in the heart from reaching the detector. We can attempt to do the scan with your arms at your side but this may seriously affect the ability of the cardiologist to properly evaluate your exam.
  •  The imager will be positioned close to your chest and will slowly rotate around your body in a half circle.  The picture takes approximately 15 minutes and it is very important that you remain still and not move at all.
  • Once the picture is completed you will be directed to return to the waiting room until they are ready for your stress test.

Stress Testing Procedure and Stress Imaging:

Your pulse, blood pressure and ECG are monitored during and after the test. If these reach any critical level as determined by the monitoring nurse, nurse practitioner, or physician assistant, you will be given medication to counter the effect of the Lexiscan.

  •  Lexiscan will be administered through the IV.  Side effects include facial flushing, chest heaviness and shortness of breath. These will occur after about 15 to 20 seconds. These side effects, if you should have any, will last only a few minutes.
  • You will be asked at times during the test if you have any symptoms such as chest or leg discomfort or shortness of breath. If you feel unwell you should inform us at once.
  •  Lexiscan does not make your heart race fast.  There is, however, a slight increase in your heart rate.  It may also cause a decrease in  blood pressure.  These will be monitored by our RN, Nurse Practitioner or Physician Assistant.
  • Immediately after the Lexiscan injection you will be given another injection of the Nuclear Tracer for a second set of images.
  • You may be asked to walk on the treadmill at a very slow speed with no hill or incline.  This can lessen symptoms from the Lexiscan and also helps the quality of the second set of images.
  •   Your EKG and Blood pressure will be monitored for 5 minutes after you are injected with the Lexiscan.
  • When the monitoring Nurse, Physician Assistant or Nurse Practitioner determines that your vital signs have returned to their baseline, you will be released back to the waiting room to wait for your final set of images.
  • The EKG leads will be left in place on your chest as some of them will be used for the stress imaging portion.  Please do not remove them
  • You may eat, drink or take any medications at this time.  There are no further restrictions of any kind at this point.
  • Waiting time for the stress images is about 45 – 75 minutes after the stress test.
  • The stress imaging procedure is the same as the one used for resting images except that wires will be placed on 3 of the remaining EKG leads.  The imager will use your heart rate to format the pictures.
  • This picture takes about 10 – 15 minutes. It is again very important that you remain as still as possible.
  • Once this picture has been completed, your procedure is complete.  The length of time from beginning to end is approximately 3 – 4 hours.
     

What are the risks?

  • In recommending this procedure your doctor has balanced the benefits and risks of the test against the benefits and risks of not proceeding. Your doctor believes there is a benefit of you having an EST.
  • There is a small radiation exposure from the radioactive drug, but this is generally no more than you would receive from any other X-Ray procedure such as a CAT Scan or some X-Ray Procedures.
     

The procedure is generally very safe, however a few risks include

  • mild angina e.g. chest pain
  • shortness of breath
  • sore muscles or joint pain
  •  fainting (rare)
  •  An abnormal heart rhythm that continues for a long time. This may require further treatment to correct  (rare)
  • heart attack (extremely rare)
  •   death as a result of this procedure is extremely rare ( less than 1 in 10,000 patients)
  • The risks are higher if you already have blocked arteries in the heart (Coronary Artery Disease)