IBHRE Syncope and Autonomic Disorders 2 — Questions and Answers
Question 1: In the VASIS (Vasovagal Syncope International Study) classification, Type 2B vasovagal syncope is characterized by:
- Cardioinhibitory response without asystole
- Cardioinhibitory response with asystole ≥3 seconds (Correct answer)
- Pure vasodepressor response
- Mixed equal bradycardia and hypotension
Correct answer: Cardioinhibitory response with asystole ≥3 seconds
VASIS Type 2B is defined as a cardioinhibitory response with asystole of ≥3 seconds, which may favor pacemaker implantation in selected patients.
Question 2: The standard tilt table test is typically performed at what upright angle?
- 45 degrees
- 60 degrees
- 70 degrees (Correct answer)
- 90 degrees
Correct answer: 70 degrees
The Westminster protocol and most international guidelines recommend a tilt angle of 70 degrees as the standard for evaluating neurally mediated syncope.
Question 3: Fludrocortisone reduces syncope primarily by:
- Increasing heart rate through sympathetic stimulation
- Increasing blood volume via renal sodium and water retention (Correct answer)
- Decreasing peripheral vascular resistance
- Blocking vagal efferent signals to the heart
Correct answer: Increasing blood volume via renal sodium and water retention
Fludrocortisone is a synthetic mineralocorticoid that promotes renal sodium retention and fluid expansion, increasing central blood volume and reducing orthostatic hypotension.
Question 4: Syncope occurring during exercise in a young patient should raise concern for which underlying condition?
- Vasovagal syncope
- Hypertrophic cardiomyopathy (Correct answer)
- Orthostatic hypotension
- Carotid sinus hypersensitivity
Correct answer: Hypertrophic cardiomyopathy
Exercise-induced syncope in young patients is a red flag for obstructive or arrhythmic cardiac causes, with hypertrophic cardiomyopathy being a leading concern.
Question 5: The autonomic response in vasovagal syncope involves activation of which reflex?
- Hering-Breuer reflex
- Bainbridge reflex
- Bezold-Jarisch reflex (Correct answer)
- Cushing reflex
Correct answer: Bezold-Jarisch reflex
The Bezold-Jarisch reflex, triggered by activation of cardiac C-fibers (mechanoreceptors) in the inferior left ventricular wall, causes reflex bradycardia and vasodilation.
Question 6: On an implantable loop recorder (ILR) in a patient with recurrent syncope, which finding best supports a neurally mediated (vasovagal) mechanism?
- Sustained monomorphic ventricular tachycardia
- Gradual progressive bradycardia leading to asystole coinciding with syncope (Correct answer)
- Sudden onset complete AV block without preceding slowing
- Rapid ventricular response during atrial fibrillation
Correct answer: Gradual progressive bradycardia leading to asystole coinciding with syncope
A gradual progressive sinus bradycardia followed by asystole during spontaneous syncope on ILR is the hallmark ILR pattern of neurally mediated syncope.
Question 7: POTS is most commonly seen in which demographic group?
- Elderly men over age 65
- Young women between ages 15 and 50 (Correct answer)
- Middle-aged men between ages 40 and 60
- Pre-pubertal children under age 10
Correct answer: Young women between ages 15 and 50
POTS predominantly affects young women in the second through fourth decades of life, with a female-to-male ratio of approximately 5:1.
IBHRE Syncope and Autonomic Disorders 2
In the VASIS (Vasovagal Syncope International Study) classification, Type 2B vasovagal syncope is characterized by: