Stress Echocardiography

Stress echocardiography (stress echocardiography; synonym: stress echocardiography) is a diagnostic procedure in cardiology (study of the heart) that can be used, among other things, to evaluate coronary artery disease (atherosclerosis of the coronary vessels/supplying vessels). Stress echocardiography is the term used for an ultrasound examination of the heart that can be used to precisely determine the effect of physical stress on the heart and, indirectly, the blood supply to the heart.

Indications (areas of application)

  • Localization and assessment of the relevance of ischemia (reduced blood flow to the heart) – With the help of stress echocardiography, in addition to the localization of the area of ischemia, it is also possible to classify the relevance of stenosis (vasoconstriction) of the coronaries (coronary arteries) in the presence of coronary artery disease.
  • Angina pectoris (“chest tightness”; sudden onset of pain in the cardiac region) on exertion without ECG change – If chest tightness sensations or other angina pectoris-like symptoms occur without causing a change in the ECG when an exercise ECG is performed, the use of stress echocardiography is indicated.
  • Follow-up after PTCA (percutaneous transluminal coronary angioplasty) and bypass surgery – Both PTCA and bypass surgery, in which an endogenous artery or vein is designed to take over the function of the stenosed (narrowed) coronary artery, serve to improve blood supply to the myocardium (heart muscle). Stress echocardiography can be used to check the extent to which myocardial function is preserved in the respective areas of blood supply after the procedures have been performed.
  • Unclear ST segment change in the ECG – Especially in young women or taking medication (digitalis – foxglove preparations), the relevance of the change in the ECG is difficult to assess, so stress echocardiography should be used as a diagnostic tool for closer examination.
  • Left bundle branch block (LSB) – When left bundle branch block (defective conduction of impulses in the heart) occurs, stress echocardiography is a useful additional diagnostic method.
  • Pacemaker control – In the context of an extended pacemaker control, the procedure can be used.
  • Detection of inner layer ischemia during exercise – In the presence of coronary artery disease, the procedure can be used to detect inner layer ischemia of the myocardium.
  • ST-segment changes in diabetes mellitus – Diabetes is an important risk factor for the development of coronary artery disease and myocardial infarction (heart attack). The nerve damage in diabetes mellitus can also impair the perception of warning symptoms of the heart, so regular checks by ECG and stress echocardiography are useful and necessary.
  • Vitality detection of myocardium – Experimental studies have demonstrated that noncontracting (immobile) but still vital myocardium coexists with irreversible necrosis (nonvital tissue) after myocardial infarction. The noncontracting tissue can be detected by stress echocardiography and therapeutically restored to contraction by reperfusion measures (measures to restore blood flow) such as PTCA (“hibernating myocardium”).

Contraindications

  • Acute phase of unstable angina – In cases of new-onset angina or increase in symptoms, the patient should not be initially examined by stress echocardiography. It is indispensable that stabilization of the patient is achieved first and only then the performance of an ischemia test (stress ECG, myocardial scintigraphy or stress echocardiography).
  • At least moderate aortic stenosis – Depending on the opening area of the aortic valve (closure valve of the connection of the left ventricle and the aorta), the examination is a contraindication due to the increased risk of complications.
  • Hypertrophic obstructive cardiomyopathy – In this heart disease, among other symptoms, there is an enlarged left ventricle. The presence of this cardiomyopathy is an absolute contraindication.
  • Severe uncontrolled hypertension – Due to the high risk of complications, effective long-term blood pressure lowering must occur before the procedure is performed.
  • Contraindications of pharmaceuticals – Depending on the form of stress echocardiography procedure, a drug is administered to achieve the stress state. Accordingly, the contraindications are also dependent on the particular drug.

Before the examination

  • Medication history – In addition to a general history, the examining physician must ask about any medications taken by the patient, as they may be harmful from exposure or may reduce the value of the echocardiogram.
  • Food abstinence – Four hours before the examination, the patient should not eat any food.
  • Nicotine abstinence (refrain from tobacco use).

The procedure

To achieve stress on the heart, various methods of stress echocardiography can be used:

  • Physical stress – By applying physical stress that causes extra work for the heart, cardiac output can be increased. This form of stress echocardiography is also called dynamic stress echocardiography. The method allows an allocation of the ischemia area to the supplying coronary artery, which is extremely important in therapy planning and can not be achieved by the stress ECG, contrary to common belief.
  • Pharmacological stress – To achieve drug-mediated stress on the heart, for example, a vasodilator (vasodilating drug e.g. dipyridamole or adenosine) is administered, which can induce ischemia in the stenotic areas via “pooling” of blood in the peripheral vessels. If necessary, theophylline can be applied as an antidote. Another option is infusion of a short-acting sympathomimetic, which stimulates the sympathetic nervous system (“activating” part of the autonomic nervous system). Pharmacological substances used include dobutamine or arbutamine. These substances increase the oxygen consumption of the heart. As a possible antidote, a beta-blocker can be given. Among other things, this method can be used to detect wall motion abnormalities (WBS) of the heart as a result of exercise-induced myocardial ischemia. An advantage of this method is that patients who cannot be examined ergometrically (by means of physical exercise) and who have, for example, peripheral arterial occlusive disease, orthopedic or neurological concomitant diseases can be examined by administering the drug.
  • Transesophageal (“across the esophagus”) atrial pacing – This method relies on rapid atrial pacing in combination with transesophageal (“across the esophagus”) echocardiography. The method is not used regularly and is to be used only for special questions.

Regardless of the examination method, a multi-lead ECG should be written down and assessed during the examination. The presence of a physician as well as an emergency kit including defibrillator and the competence for resuscitation must be ensured! The following findings may be detected during stress echocardiography:

  • Ischemia (reduced blood flow): myocardial segment (myocardial portion) with inducible wall motion disturbance under stress.
  • Scar: myocardial segment remains akinetic under low-dose and high-dose.
  • Hibernating myocardium (“hibernation” (German: Winterschlaf); hibernating heart): here there is a chronic underperfusion with secondarily adapted reduced contraction of the myocardium (reversible-ischemic loss of function); the myocardial segment shows an increase in regional contractility under low-dose, deterioration of regional contractility under high-dose.
  • Stunning myocardium ((Occurrence, for example, in the first weeks after acute myocardial infarction (heart attack) with successful lysis therapy (therapeutic measure to dissolve a blood clot) or acute PTCA / percutaneous transluminal coronary angioplasty): the heart is reperfused, but is still hypo- or akinetic is; it shows under low-dose and high-dose an increase in regional contractility.
  • Clinically, transitions between stunning myocardium and hibernating myocardium may occur; eg.B. in the case of successful lysis therapy after myocardial infarction with continued relevant residual stenosis (“residual narrowing”) in the supplying coronary artery (coronary artery).

After the examination

Following the examination, the patient is still monitored to detect any adverse effects of the stress on the heart and, if necessary, to treat them quickly.

Possible complications

  • Severe angina or dyspnea (shortness of breath).
  • Clear occurrence of distinct wall motion abnormalities of the ventricles of the heart
  • Pathological stress ECG (eg, ischemia signs in previously unremarkable resting ECG).
  • Repeated arrhythmias of the ventricles.
  • Pronounced drop in blood pressure or marked increase in blood pressure
  • Supraventricular tachycardia (arrhythmia originating in the atria of the heart) and atrial fibrillation
  • Sudden cardiac death (PHT)
  • Myocardial infarction (heart attack)

Important Notice. In patients with cardiovascular instability, SonoVue ultrasound contrast agent can cause severe cardiac arrhythmias. Patients at risk are those who are administered dobutamine during stress echocardiography, according to a red-hand letter from the manufacturer.