DOBUTAMINE STRESS ECHO

When a stress test on a treadmill or other tests are not conducted due to any associated medical condition, such as inability to walk, severe pain in the legs during the test, or another patient's similar condition, your doctor may decide to use intravenous medication such as dobutamine.

This medicine is diluted in a serum and is administered in the vein, slowly and under strict control. It makes the heart beat faster, as when you exercise.

Indications obtained from the study:

• Observe the blood flow as related to the heart walls, to determine whether it is secondary to an obstruction of a coronary.

• During a convetional stress test changes may suggest a coronary disease, or an inability to perform the test due to a medical problem associated with knee pain or poor physical fitness, among others.

• In people who have suffered a myocardial infarct (muscle death) it is adviseable to examine other areas of the heart that might be at risk and other procedures may be used to determine if the blockage can be removed to avoid another attack.

• Assessment of areas that are still viable (not dead) and are susceptible to procedures that may improve blood flow such as angioplasty or coronary surgery.

• To assess the situation of the patient who will be undergoing surgery.

• The degree of the lesion or the impact of the heart disease.

What is the study?:

The Stress Echo is an ultrasound diagnostic procedure for assessing the left ventricular contractility at rest and during and after drug administration.

It is done in four phases: without medication or with low and high doses and a recovery phase without the medication. Heart rate increases progressively until at least 85% of the maximum frequency expected for the patient's age. Sometimes it is necessary to administer other medications or move the patient´s arms to increase heart beat and achieve the goal.

Each of the phases records heart beat, blood pressure, oximetry, and both the ultrasound images and the electrocardiogram.

In the end, responses and lines and images of each stage are compared and evaluated, to prepare a report with the conclusions of a doctor specialized in this type of study.

Preparation for the study:

• The patient must fast at least 6 hours before the test.

• The preparation and test takes about an hour.

• Your doctor will tell you which drugs have to be suspended before the test.

• Tell your doctor if you are or suspect to be pregnant or if you are breastfeeding.

• Some factors may interfere with the test such as smoking or caffeine within three hours before the procedure.

• Drugs such as beta blockers (atenolol, carvedilol, nebivolol, metoprolol, propranolol and bisoprolol) affect the increase in heart rate.

To perform the study:

• An IV conduit will be placed in the arm before the procedure to inject liquid medications and dobutamine.

• The patient will lie on the left side on a stretcher and may change position during the procedure.

• Electrodes are placed in the chest connected to an EKG monitor that records the heart's electrical activity. During the procedure, vital signs (heart rate, blood pressure, respiratory rate and blood oxygen level) are monitored. Graphic records of electrocardiogram at rest and during the entire test will be also registered.

• An echocardiogram (heart ultrasound) will be conducted to obtain various measurements of the heart and observe its movement before administering dobutamine. This is the basal phase.

• Start the dobutamine drip at a rate that will increase steadily until it reaches the target heart rate (determined by the physician taking the echo according to the age and physical condition of each patient) or until the maximum dose of dobutamine is achieved.

• Every time the dip rate of dobutamine increases, all vital signs are taken, as well as electrocardiogram and echocardiography images in different views to be able to compare the different phases.

• The echocardiographer moves the transducer or probe in the chest to obtain different views of the heart and you may hear a sound caused by the flow of blood through the heart.

• Once it has reached the target heart rate or the maximum dose of dobutamine the drug is suspended. Vital signs, electro and echocardiogram will continue to be monitored for 10-15 minutes until everything returns to its initial state.

• The patient shall inform the physician if he/she experiences chest pain, palpitations or lack of breath. It is normal to experience tingling in the head or body tremor.

• Once all images have been obtained and both the heart rate and blood pressure return to initial levels, the electrodes are removed.

After the study:

The patient may resume his/her diet and continue their activities as before the test, unless the doctor says otherwise, but in general no special care is necessary. It is possible that the physician gives the patient diagnosis or treatment options after the study.

Risks involved:

It is very safe and the procedure is performed under strict medical supervision and continuous cardiovascular monitoring. Chest pain may be present, as well as a considerable increase in blood pressure, arrhythmia, nausea or fatigue. Related lterature reports the possibility of a heart attack, although it is very rare. Significant changes in heart rate or ECG are rare, but if present, immediate treatment is necessary. People who are likely to have such complications are excluded from these tests and other studies are chosen to confirm the diagnosis of the patient under investigation.