Syncope and Collapse: Diagnostic Tests

Obligatory medical device diagnostics.

  • Vital signs including temperature, oxygen saturation, and respiratory rate.
  • Repeated blood pressure measurement* on both arms with cuff adjusted to arm circumference.
  • Electrocardiogram* (ECG; recording of the electrical activities of the heart muscle; here: 12-lead ECG) – for basic diagnosis or when arrhythmogenic syncope (due to cardiac arrhythmia) and/or structural cardiac syncope (due to structural heart disease) is suspected[Arrhythmia during syncope is probative of cause; normal ECG during syncope does not rule out rhythmogenic cause].

Optional medical device diagnostics – depending on the results of the history, physical examination, and obligatory laboratory parameters – for differential diagnosis.

  • Orthostasis test (Schellong test).
    • 1st part (measurements in lying position): blood pressure and pulse are measured in minute intervals. Duration: 3-10 minutes.
    • 2nd part (measurements in standing position): immediately following the last lying measurement, blood pressure and pulse are measured in standing position (instant value). During the standing period, at minute intervals, the measurement is repeated. Duration: 5-10 minutes

    Assessment: the Schellong test is positive if the systolic blood pressure persistently drops by at least 20 mmHg and / or diastolic by at least 10 mmHg in the standing position within 3 minutes after standing (compared to resting values after 4 minutes lying down) or at 60 ° elevation on the tilt table.Alternatively, one speaks of orthostatic hypotension in the case of a drop of more than 30 mmHg in hypertensive patients with blood pressure above 160 mmHg in the supine position. In these cases, a so-called orthostatic dysregulation is very likely.Indication: V. a. reflex or orthostatic dysregulationNote: The tilt table examination has recommendation grade IIa.The S1 guideline recommends an active standing test with blood pressure/pulse measurements in the supine position and at least 3 minutes in the standing position(so-called shortened Schellong test).Presence of orthostatic hypotension:

    • (blood pressure drop ≥ 20 mmHg systolic and/or ≥ 10 mmHg diastolic or systolic blood pressure value < 90 mmHg after 3 minutes) and
    • POTS (pulse increase ≥ 30 bpm (in adolescents younger than 19 years ≥ 40 bpm) or absolute pulse rate ≥ 120 bpm after 10 minutes.
  • Long-term ECG (Holter ECG) (ECG applied over 24 hours; for more accurate assessment of cardiac function within the day) – indications [ESC guideline: recommendation grade IIa]:
    • The clinic or ECG findings are suggestive of arrhythmogenic syncope; and
    • If there is a high likelihood that syncope will occur again soon; and
    • When the patient might benefit from specific therapy if the cause is found.
  • Event recorder (long-term ECG over a prolonged period of usually 24 hours; cardiac arrhythmias?) – for recurrent (recurring) syncope and suspected cardiac (heart-related) cause [recommendation grade 1a].
  • Implantable event recorder (ILR) – for recurrent syncope without prodromes (precursors; early warning signs) and with risk of injury to determine the indication for a pacemaker, if necessary [S1 guideline].
  • Electrophysiologic study (EPU) [ESC guideline] – in patients with unexplained syncope and bifascicular block (impending high-grade AV block) or when tachycardia is suspected ; indications for pacemaker implantation (pacing recommendations) include the following:
    • Bisfascicular block (IIb recommendation).
    • Prolonged sinus node recovery time (IIa recommendation).
    • HV interval (time between excitation of His bundle (His spike) and first ventricular excitation in the lead) of > 70 msec.
  • Long-term blood pressure measurement (24-hour blood pressure measurement) – if blood pressure regulation disorders are suspected.
  • Echocardiography (echo; cardiac ultrasound) – suspected cardiac cause of syncope or suspected structural heart disease (e.g., aortic valve stenosis, mitral valve stenosis; pericardial tamponade; aortic dissection).
  • Doppler sonography (ultrasound examination that can dynamically visualize fluid flow (especially blood flow)) of the carotids (carotid arteries) – if plaques (deposits) or stenoses (vasoconstrictions) in the carotids are suspected; no carotid imaging in cases of fainting or syncope as long as no other neurological symptoms are present
  • Coronary angiography (radiologic procedure that uses contrast agents to visualize the lumen (interior) of the coronary arteries (arteries that surround the heart in a wreath-like fashion and supply blood to the heart muscle) – if coronary artery disease (CAD) is suspected)
  • Encephalogram (EEG; recording of the electrical activity of the brain) – for neurological abnormalities such as Parkinson’s symptoms, ataxia or cognitive disorders; if epilepsy is suspected.
  • Computed tomography/magnetic resonance imaging of the skull (cranial CT or.cCT/cranial MRI or cMRI) – if neurologic cause such as cerebral ischemia is suspectedNote: In a meta-analysis, cranial CT was performed in adults with syncope in more than one in two patients. This revealed intracranial (“inside the skull“) causes in 1-4% of cases. CONCLUSION: In low-risk patients with syncope, the indication for cranial CT should be restrictive.
  • Computed tomography (CT) with angiography (imaging of blood vessels) of the pulmonary arteries (CTPA) – as a basic diagnostic tool in suspected pulmonary embolism [gold standard]Alternative: pulmonary scintigraphy: V/P scintigraphy (ventilation/perfusion scintigraphy) (sensitivity (percentage of diseased patients in whom the disease is detected by using the test, i.e., a positive test result occurs): Approx. 78 %; Specificity (probability that actually healthy persons who do not suffer from the disease in question are also detected as healthy by the procedure): 98 %)Note: Clarification in patients with symptoms such as dyspnea (shortness of breath), clinical signs of deep vein thrombosis (DVT) or ECG signs such as a right bundle branch block.

* See also under “Symptoms – Complaints/Canadian Syncope Risk Score.”

Further notes

  • According to the current 2018 European Society of Cardiology “ESC Guidelines for the diagnosis and management of syncope,” routine performance without specific suspicion of chest radiography (chest X-ray) and cranial CT is not recommended.
  • In patients with syncope and intermediate risk, the sensitivity (percentage of diseased patients in whom the disease is detected by use of the test, ie, a positive test result occurs) for identification of a serious event within 1 week by ECG after examination for at least 12 hours was 89%; the specificity (probability that actually healthy persons who do not have the disease in question are also identified as healthy by the procedure) was only 78%.