The Dobutamine Stress Echocardiograph (DobECHO) is usually ordered for Patients who are experiencing symptoms of chest discomfort, shortness of breath or palpitations (irregular heart beat). Often these symptoms are related to physical activity.
The DobECHO is used as a test for the detection of coronary artery disease (a build up of plaque in the blood vessels to the heart causing a partial or complete obstruction). It is a test performed in Patients who are unable to exercise for various reasons such as arthritis, poor circulation in the legs or lung disease. It is also used in some Patients to determine whether damaged heart muscle is dead or not.
Dobutamine is a drug, which essentially simulates the changes that occur during exercise. The Dobutamine is given by a constant intravenous infusion. The heart rate will increase and the force of contraction of the heart will become stronger as increasing doses of Dobutamine are administered. The blood pressure response is variable. Usually the blood pressure either does not change much or may even drop a little during the infusion.
Prior to the DobECHO an Allied Heath Professional will take a brief history including medication history and symptoms, ask you about your risk factors (High blood pressure, Cholesterol level, Smoking, Diabetes, etc…) and then explain the test to you. You will then be examined to make sure there is no reason to cancel the DobECHO. Once this is completed you will be asked to sign a consent form. It is important you bring all of your medications or an up to date list.
The Allied Health Professional will then prepare the skin so the Electrocardiogram (ECG) can monitor your heart rhythm continuously throughout the DobECHO without interference.
For Men this involves shaving the skin, rubbing it vigorously with alcohol and then gently roughening the skin with special abrasive paper. For Women the skin still has to be rubbed with alcohol and then gently roughed. Ten electrodes are then applied to the chest. The electrodes are placed in a position so that the Echocardiographer can obtain good images of the heart.
Following this, an intravenous line will be established for the delivery of Dobutamine using a special IMED infusion pump and a specific protocol whereby the drug dose is gradually increased. If during the Dobutamine infusion it becomes obvious to the Allied Health Professional that the heart rate response is inadequate a drug called Atropine will be give to increase the heart rate.
During your DobECHO there are always 2 experienced Physicians immediately available. One of these Physicians is experienced in the interpretation of Echocardiography. All the necessary resuscitation equipment and emergency medications are readily available. There are 2 Allied Health Professionals present throughout the test. At the Kingston Heart Clinic we have performed over 7,000 DobECHOs.
Before the DobECHO your blood pressure and ECG will be recorded. The Echocardiographer will then take the resting ultrasound images of the heart. Ultrasound images will be viewed continuously throughout the test and images aquired at low dose Dobutamine, pre-peak Dobutamine and peak Dobutamine. During the DobECHO you will be asked, how you are feeling and your blood pressure will be recorded every 3 minutes. Your heart rhythm is monitored continuously and an ECG is taken every 3 minutes as a permanent record for the Physician to review. If you are experiencing any difficulties this must be related to your Allied Health Professional.
The DobECHO is a heart rate limited, symptom limited and protocol limited test. The target heart rate is 85% of your maximum predicted heart rate (220-Age in years) plus an extra 10 beats per minute. The test will stop if you complete the protocol, develop symptoms, achieve your target heart rate, or develop multiple wall motion abnormalities by ultrasound imaging, whichever occurs first. The test will also be stopped if you tell the Allied Health Professional to stop. The Allied Health Professional because of changes in the ECG, Ultrasound images or blood pressure may also stop the DobECHO test.
At the completion of the DobECHO your clinical condition, blood pressure, and ECG will be monitored until everything returns to baseline. Once this has occurred a final set of ultrasound images are obtained.
At our facility, all DobECHOs are interpreted at a later time by a Physician and a formal written report will then be mailed to your Doctor, which will be received within 10 days. Tests which are significantly abnormal are interpreted immediately and FAXed to the referring Physician. If necessary, the patient will be interviewed and advice and/or drug therapy initiated