The following are key points to remember from the Practical Instructions for the 2018 European Society of Cardiology (ESC) Guidelines for the Diagnosis and Management of Syncope:

1. Reflex syncope is the most frequent cause of syncope in any setting and at all ages, with cardiac syncope as the second most common cause.
2. Transient loss of consciousness is characterized by four specific characteristics: short duration, abnormal motor control, loss of responsiveness, and amnesia for the period of loss of consciousness.
3. Carotid sinus massage (CSM) preferably is performed during continuous electrocardiogram (ECG) and noninvasive beat-to-beat blood pressure (BP) monitoring. Carotid sinus hypersensitivity is diagnosed when CSM elicits abnormal cardioinhibition (i.e., asystole ≥3 seconds) and/or vasodepression (i.e., a fall in systolic BP >50 mm Hg).
4. It is recommended that the following method be adopted for tilt testing:
• Patients should be fasted for 2–4 hours before the test.
• Ensure a supine pre-tilt phase of ≥5 minutes when there is no venous cannulation, and of ≥20 minutes when there is venous cannulation.
• Tilt angle between 60 and 70 degrees.
• Passive phase of tilt of ≥20 minutes in duration and a maximum of 45 minutes.
• Use either sublingual nitroglycerin or intravenous isoproterenol for drug provocation if the passive phase is negative. The duration of the drug-challenge phase is 15–20 minutes.
• For nitroglycerin challenge, a fixed dose of 300–400 μg sublingually administered with the patient in the upright position.
• For isoproterenol challenge, an incremental infusion rate from 1 μg/min rising to 3 μg/min to increase average heart rate by about 20–25% over baseline.
• The test should be continued until complete loss of consciousness occurs or completion of the protocol.
• Tilt tables have only one specific requirement: the tilt-down time should be short (<15 seconds), as longer times increase the duration of precipitated asystole.
5. Autonomic function testing should be performed by a specialist trained in autonomic function testing and interpretation. The required equipment includes beat-to-beat BP and ECG monitoring, a motorized tilt table, 24-hour ambulatory BP monitoring devices, and other specialized equipment depending on the range of testing.
6. During the Valsalva maneuver, the patient is asked to conduct a maximally forced expiration for 15 seconds against a closed glottis, i.e., with closed nose and mouth, or into a closed loop system with a resistance of 40 mm Hg. The hemodynamic changes during the test should be monitored using beat-to-beat continuous noninvasive BP measurement and ECG.
7. During the deep-breathing test, the patient is asked to breathe deeply at 6 breaths per minute for 1 minute under continuous heart rate and BP monitoring. In healthy individuals, heart rate rises during inspiration and falls during expiration.
8. Classical orthostatic hypotension is defined as a sustained decrease in systolic BP ≥20 mm Hg, diastolic BP ≥10 mm Hg, or a sustained decrease in systolic BP to an absolute value <90 mm Hg within 3 minutes of active standing or head-up tilt of at least 60 degrees.
9. Postural orthostatic tachycardia syndrome patients, mostly young women, present with severe orthostatic intolerance (light-headedness, palpitations, tremor, generalized weakness, blurred vision, and fatigue) and a marked orthostatic heart rate increase (>30 bpm, or >120 bpm) within 10 minutes of standing or head-up tilt in the absence of orthostatic hypotension.
10. The BP fall of orthostatic vasovagal syncope differs from that in classical orthostatic hypotension. In vasovagal syncope, the BP drop starts several minutes after standing up and the rate of BP drop accelerates until people faint, lie down, or do both. Hence, low BP in orthostatic vasovagal syncope is short-lived. In classical orthostatic hypotension, the BP drop starts immediately on standing and the rate of drop decreases, so low BP may be sustained for many minutes.

Keywords: Arrhythmias, Cardiac, Amnesia, Blood Pressure, Carotid Sinus, Catheterization, Dizziness, Electrocardiography, Glottis, Heart Arrest, Hypotension, Hypotension, Orthostatic, Isoproterenol, Nitroglycerin, Orthostatic Intolerance, Postural Orthostatic Tachycardia Syndrome, Primary Prevention, Syncope, Syncope, Vasovagal, Tilt-Table Test, Tremor, Valsalva Maneuver

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