Doctor Susana Gomes

Cardiologist

Pharmacologic stress echocardiography

HPA Magazine 13

The high prevalence of coronary heart disease (“blockage” of the heart vessels) and consequent ischemia - low oxygen supply to the heart muscle, with angina pectoris and myocardial infarction (called “heart attack”), resulted in the need for complementary tests to evaluate and diagnose this pathology.
The “gold standard” test for assessing coronary disease is coronary angiography or cardiac catheterization. However, since cardiac catheterization is an invasive procedure, it should be performed on patients with a strong suspicion of coronary artery disease who will need a revascularization procedure or stent implantation.
Non-invasive exams include the classic treadmill stress test or the exercise echocardiography. Although they are widely used and important, they have limitations, especially in people with some type of mobility difficulty and they are sometimes inconclusive (the result is sometimes doubtful). This is when a pharmacologic stress echocardiography is needed. 

What is a pharmacologic stress echocardiography?

An echocardiogram is an examination performed by means of a probe that emits ultrasounds thereby obtaining images of the heart. An echocardiogram is usually performed at rest.
When necessary, the heart can be assessed in effort or overload, by performing a pharmacological overload echocardiogram, also known as a stress echo, where medication is administered to accelerate the heart, simulating a physical effort.
With this examination, functional or structural alterations that occur under stress can be detected, both in the heart muscle (myocardium), as well as in the coronary arteries and valves.

What is the purpose of this exam? What are its indications?

The pharmacologic stress echocardiogram, allows the cardiologist to identify areas of the myocardium that might be unable to work properly in effort, meaning that there is not enough blood flow irrigating a specific part of the heart due to an obstruction of the coronary arteries.
This myocardial ischemia study can be used both in patients with suspected coronary disease, as well as in the follow-up of patients who have already undergone revascularization procedures (post-stent implant or cardiac bypass surgery). It also studies the myocardial viability after a heart attack, that is, to identify areas of the heart that do not work properly at rest, but that have recovery capacity.
The stress echocardiography can also help to clarify the severity of a valve problem, especially in aortic valve stenosis with depression of myocardial function.

How is a pharmacologic stress echocardiogram performed?

The pharmacological stress echocardiogram is performed by a team of professionals consisting of a cardiologist, a cardiopneumologist technician and a nurse, all with extensive experience in this area.
The examination is performed while the patient is lying down. An intravenous serum is placed through which the drugs that cause the cardiac effort are administered while electrodes are placed on the chest to monitor the heart rhythm and perform the electrocardiogram (ECG).
The light in the room is dimmed so that the images on the ultrasound screen can be better viewed.
A transparent gel is applied on the left side of the patient’s chest where the probe or transducer is placed. This transducer emits and receives an ultrasound beams reflected as images on the ultrasound monitor. Blood pressure measurements are also collected. Images are obtained before, during and after the administration of the medications that cause cardiac stress.
Throughout the exam, images are recorded and the electrocardiogram is recorded continuously. It is also sometimes necessary to administer an ultrasound contrast.
During the exam a warm sensation may be felt and the heart may beat faster and stronger (palpitations). A slight headache, dry mouth, tiredness and a strange sensation on the chest may be felt. These effects, which relate to cardiac exertion, are temporary.
At the end of the exam, an antidote is administered to reverse all the effects of the medication used to cause the cardiac effort.
The duration of this exam is 45-60 minutes. After the exam, the patient must give himself a few additional minutes for the body to recover, before returning to a normal daily routine.

How to prepare for this exam?

The pharmacologic stress echocardiogram requires a period of fasting of 4 hours. A small quantity of liquids can be taken with medication if necessary. 
It may be necessary to suspend some of the patient’s normal medication for 1-2 days before the exam in order to avoid interference with the medication administered for the pharmacologic stress echocardiogram.
In the 12 hours prior to the exam, the following food is prohibited, as they may interfere with the test results and their interpretation: coffee, tea, chocolate, soft drinks and alcoholic beverages.

Benefits

The diagnostic value of a stress ultrasound is much higher than that of a conventional stress test. However, even with a technically advanced examination, lesions and diagnoses may, although rarely, not be detected.

Risks

This exam is safe. There are risks involved but they are slight and comparable to that of any more vigorous effort.
Ultrasound is innocuous to one’s health, but the medication administered can cause some side effects. The inherent risks range from more frequent reactions, such as blood pressure changes, feeling ill and heart rhythm alterations, including arrhythmias, to less frequent situations such as allergic reactions. Cases of acute myocardial infarction and cardiac arrest have been described, but these are extremely rare. Therefore, as a precaution, medical assistance is available, including the equipment necessary in the event of any complications.

Other reliable and scientifically recognized alternative interventions

There are other reliable tests as an alternative to the Stress Echocardiogram, such as Myocardial Scintigraphy and Stress MRI, each have advantages and disadvantages when compared with this test.

Conclusion

The pharmacologic stress echocardiogram is a test that combines high diagnostic accuracy, is safe, non-invasive, easily accessible and does not use ionizing radiation.