If the cardiac ECG, exercise ECG, and cardiac ultrasound (echocardiography) are abnormal, but the diagnosis is not accurate, myocardial scintigraphy is the method of choice. It is non-invasive and has a high informative value.

What is myocardial scintigraphy?

The doctor wants to recognize how circulatory disorders affect the heart muscle. The cause of the disturbed blood circulation is usually in constrictions of the coronary arteries.

Myocardial scintigraphy is a gentle, nuclear-medical diagnostic procedure to examine the blood flow, metabolism and mass of the heart muscle. The examination of the heart takes place in two phases: under stress and at rest.

Subsequently, the findings are compared with each other. In the scintigram, the doctor can see how circulatory disorders affect the heart muscle. The cause of the disturbed blood circulation is usually in constrictions of the coronary arteries. A lack of blood flow to the heart carries the risk of a life-threatening heart attack. Myocardial scintigraphy can determine if the extent of circulatory problems necessitates cardiac catheterization and may even save some patients.

Function, effect & goals

Myocardial scintigraphy enables the doctor to determine which amount of blood reaches the heart at rest and under stress. By comparing the images, he can determine whether different areas of the heart are less well supplied with blood during exercise than others. Low blood flow could be a sign of vasoconstriction and an increased risk of heart attack.

If the patient has already had a heart attack, the size of the scar, the extent of tissue damage, and residual blood flow to the infarcted area can be determined. The result determines whether a bypass operation is required or a stent must be set. Beyond these questions, myocardial scintigraphy provides insights into the pumping power of the heart and the physical capacity of the patient, who is worse off after a heart attack than in healthy, well-perfused tissue.

For myocardial scintigraphy, an access to the brachial vein is laid over which, during the exercise test on the bicycle ergometer, a slightly radioactively marked carrier substance can be injected, which makes the cardiac vessels visible. In patients who are physically limited, z. B. due to orthopedic problems or if the blood pressure at rest is already too high, it is possible to administer while lying a drug for stress.

The stress test is controlled by a doctor and monitored by an ECG. In the phase of increased load, a radioactive carrier is injected via the access. After the exercise follows a rest period of 30 to 60 minutes, in which the patient should eat a brought as fatty as possible meal. After the resting phase, the gamma camera takes about 20 minutes while lying down and evaluates it. Based on these images, it is decided whether a rest examination is still required.

Sometimes the stress test is enough. If a check-up is still required for clarification, radioactivity in the heart must first be removed for about 2 hours before the second part of the exam follows. Then follows the same procedure again, only without load.

Myocardial scintigraphy always makes sense to rule out coronary heart disease (CHD) if the following risk factors persist:

  • high blood pressure
  • Smoke
  • overweight
  • Diabetes mellitus
  • elevated cholesterol levels
  • familial disposition to heart disease
  • Angina pectoris
  • Abnormalities in the ECG

Because myocardial scintigraphy determines the extent of the circulatory disorder, it can help to optimize treatment and avoid unnecessary surgical procedures. After successful treatments, it can be used as a non-invasive method of controlling new vascular constrictions. It can also determine an individual heart risk. The examination is offered by all statutory and private health insurance companies as a standard benefit.

Risks, side effects & dangers

Side effects such as allergies are rare in radioactive substances, rather in X-rays in response to contrast agents. The radiation exposure is low and not higher than with X-rays. Nevertheless, a very low risk of cancer as a delayed result can not be completely ruled out. Therefore, benefits and risks should always be weighed individually.

Even the stress phase rarely leads to complications even in patients with cardiac disease. In order to ensure an optimal informational value of the examination result, the patient must reach the highest possible level for him. In extremely rare cases it can lead to arrhythmia and a heart attack. Occasionally mild side effects such as chest tightness, a feeling of warmth, shortness of breath, a feeling of pressure in the abdomen, headache, arm and leg discomfort and dizziness may occur. However, these occur only in the case of a drug-induced stress. The radioactive substance itself does not cause any side effects.

During pregnancy, myocardial scintigraphy is performed only in exceptional cases. In breast-feeding, mothers have to take two days' breastfeeding pauses after the examination. In severe organ diseases, the stress on the cardiovascular system may be too high. Other contraindications are feverish infections, acute myocardial infarction or heart failure, uncontrollable high blood pressure, severe cardiac arrhythmias and valve defects, and acute myocarditis.

Patients should be fasted for at least 12 hours, and may only drink slightly low-carbon water. Medicines should be taken, heart medicines should be exposed for 24 hours, beta blockers even 2 to 3 days. They can be taken before the resting phase if necessary. Diabetics are allowed to eat a small, low-fat meal.

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