The "Guidelines for the diagnosis and treatment of neurally mediated syncope in children and adolescents (revised 2024)" was published by the Chinese Pediatric Cardiology Society in 2024, which is an update of the 2018 edition guidelines. The English version of the guidelines can be found on PubMed Central with the DOI: 10.1007/s12519-024-00812-7.
Since the publication of the 2018 guidelines, significant progress has been made in the diagnosis and treatment of pediatric syncope. The revised guidelines are based on the latest global research progress and evidence-based medicine, aiming to assist pediatricians in effectively managing children with syncope.
The guidelines classify the etiology of syncope in children and adolescents, including neurally mediated syncope (NMS), orthostatic intolerance (OI) syndromes such as postural tachycardia syndrome (POTS), orthostatic hypotension (OH), orthostatic hypertension (OHT), sitting tachycardia syndrome (STS), and sitting hypertension (SHT), as well as syncope caused by other factors such as arrhythmia and 器质性 heart disease.
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Initial Evaluation: Includes detailed history taking, physical examination, and standard electrocardiography. These can help diagnose some syncope types such as POTS, OH, and situational syncope directly.
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Postural Tests: For patients whose diagnosis cannot be confirmed by the initial evaluation, postural tests can be performed, including the active standing test, head-up tilt test (HUTT), and active sitting test. These tests can help diagnose NMS and determine its hemodynamic type.
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Active Standing Test: The child lies supine for 10-30 minutes first, then stands actively for 10 minutes while monitoring heart rate (HR), blood pressure (BP), and ECG. It can help diagnose POTS, OH, or OHT.
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HUTT: There are basic HUTT (BHUT) and sublingual nitroglycerin-provoked HUTT (SNHUT). In BHUT, the child lies supine on the tilt bed for 10-30 minutes, then the bed is tilted upward at an angle of 60° for 45 minutes. If no positive response occurs in BHUT, SNHUT can be performed by giving sublingual nitroglycerin (4-6 μg/kg, maximum ≤ 300 μg) and continuing to monitor for 20 minutes.
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Positive Response Criteria for HUTT: For vasovagal syncope, a positive response includes SBP ≤ 80 mmHg or DBP ≤ 50 mmHg, or mean pressure decrease ≥ 25%; HR < 75 bpm for 4-6-year-old children, < 65 bpm for 6-8-year-old children, and < 60 bpm for children and adolescents > 8 years; ECG showing sinus arrest, junctional escape rhythm, atrioventricular block (II or III degree) or cardiac arrest ≥ 3 seconds.
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Non-pharmacological Treatment: It is the first-line treatment for NMS, including patient education, increasing fluid and salt intake, physical countermaneuvers (such as leg crossing, handgrip), and exercise training. Patient education is the fundamental part, which should let patients and their families understand the nature of the disease, 诱发 factors, and preventive measures.
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Pharmacological Treatment: Indicated for children with recurrent syncope (more than twice every 6 months or more than three times per year), with risk of injury, and poor response to non-pharmacological therapy. The main drugs include midodrine hydrochloride and metoprolol. The initial dose of midodrine hydrochloride is 1.25-2.5 mg/time, once or twice daily, which can be increased to 2.5 mg/time, three times daily after 2-4 weeks. The initial dose of metoprolol is 0.5 mg/kg/day orally, twice daily, and can be gradually increased to a tolerable dose (no more than 2 mg/kg per day or the maximum adult daily dosage).
The guidelines also put forward specific suggestions for the follow-up process and efficacy evaluation of NMS, emphasizing the importance of regular follow-up, monitoring of symptoms, BP, HR, and ECG, and adjustment of treatment strategies according to the evaluation results.