In my previous blog I talked about one of the three types of stress tests, how your doctor will calculate your maximum heart rate, and what types of parameters they may be looking for during a stress test. In the second portion of the blog I will go over the other two types of stress testing, what parameters are looked for during these tests and why one may be used over the other.
The Stress ECHO test generally functions the same as the ETT with the addition of pictures of your heart to evaluate its function. The total time for this test is about 1 hour. You will be connected to the ECG stress system and then asked to walk on the treadmill or bike on an Ergometer; the same as in an ETT. You will have your HR and BP monitored to ensure that these parameters remain within safe levels. Your doctor will want you to remain on the stress equipment as long as you are able, to work your heart as hard as you can.
Once you have reached the maximum amount that you are able to give you will be asked to quickly get off the treadmill and lie on the hospital bed on your left side. This needs to be done quickly (generally within 30 seconds) because conditions within your heart can change rather rapidly. Remember, a healthy heart can recover from strenuous activity in 1 minute. The stress technician will take images and video of your heart using an Echocardiogram for your doctor to evaluate. The images that are collected can help diagnose your risk for coronary artery disease or detect heart problems that are not present at rest (e.g., if an area of the heart muscle doesn't pump as it should during exercise). It is important to tell your clinician if you feel any discomfort at all during this test as your symptoms can help identify certain heart conditions.
The Nuc Test
A Nuclear Stress test can be done in multiple ways and given for a variety of reasons. The first reason is if you are unable to perform the motion portion of the stress test due to physical difficulties. This test might be prescribed to you as an alternative. There is a common medicine called Lexiscan that is used to 'simulate' stress on the heart, where it will elevate your BP and make your heart work a bit harder. This drug is given to a patient if the doctor believes that the patient will not reach their maximum HR on their own during the physical portion of the stress test or if they are physically unable to perform the motion portion of the test. The total time for this test is about 45 minutes to 1 hour.
Secondly, there are other medicines that use a small amount of a radioactive tracer solution that is injected into the blood stream during a stress test. These medicines are used to track blood flow into the heart to evaluate the heart's function. The medicine is usually injected just after the test starts, whether or not you are sitting during the stress test or motion is involved. These tests are usually referred to as Dobutamine-Atropine Nuclear Stress tests or Adenosine or Dipyridamole Nuclear Stress Tests. You will have 2 sets of pictures taken of your heart. The first will be before the medicine has been administered and stress test started – this provides your doctor your heart's resting images. The second set of images will be taken after the stress test has finished, usually about 10 to 20 minutes after the test has been completed. The total time for this test is about 1.5 to 2 hours.
During both of these types of Nuclear stress tests your HR and BP will be monitored. Additionally, your doctor will ask you if you feel any pain in your chest or have shortness of breath. These are common symptoms of the medicines that were issued during the test, and they want to see if things feel different than normal for you. Are these pains that you usually feel or are they different? Any of these medicines will increase your heart rate and/or dilate the arteries in your heart. This test can help identify if you have blockages in your arteries that are more pronounced when the heart is stressed.
With your new found knowledge about stress testing and all it implies have a discussion with your doctor about the types of tests available and the medicines that may be used during the test. Always remember that the most important part of the test is your safety, this is why your clinicians office has automated devices such as ECG machines, heart rate monitors, and blood pressure monitors – to ensure your safety comes first.
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