Patient will present as → a 22-year-old female comes to the emergency department for a syncopal episode. Just prior to the syncopal episode, the patient experienced painful menstrual cramping. She experienced a cold sweat and palpitations with the cramping. The patient describes similar episodes to her menstrual cramps in the past. Her vital signs and physical examination are normal. ECG is unremarkable.
Vasovagal syncope (common faint, neurocardiogenic syncope, or reflex syncope) is characterized by an abrupt onset of hypotension followed by a syncopal episode often in reaction to a stressful trigger
- Caused by a paradoxical withdrawal of sympathetic stimulation and a replacement by enhanced parasympathetic (vagal) activity causing bradycardia, vasodilation, marked decrease in BP, and cerebral perfusion
- The most common cause of syncope. Most people have one episode, but for some, it is a recurrent problem
- Common triggers include strain, stress, extended periods of standing, heat exposure, or the sight of blood
- Symptoms include paleness, nausea, sweating, a rapid heartbeat, and fainting
In healthy patients with a classic history of vasovagal syncope, a normal exam, and a normal ECG, no further testing is indicated, and laboratory testing is low yield
- When a diagnosis is not certain, or when patients have multiple potential causes of syncope, serum electrolyte testing, complete blood count, and cardiac enzymes may be indicated
- Upright tilt-table study can reproduce the symptoms in susceptible people
- Can occur at any age, but if the first episode is after age 40, be reluctant to make this diagnosis
Can usually be reversed by assuming the supine posture and elevating the legs
- Treatment usually involves trigger avoidance, but may on rare occasions include β-blockers and disopyramide or a pacemaker
Question 1 |
A 63-year-old female is brought to the ED by the rescue squad after an episode of syncope at home. Her husband witnessed the event. He describes the patient as falling suddenly to the floor from a standing position. She lost consciousness for about 5 seconds, after which she rapidly regained consciousness and was oriented and appropriate. The patient remembers feeling lightheaded, nauseous, and developing “tunnel vision” prior to the event. No bowel or bladder incontinence was noted. PMH is significant for DM, HTN, and depression. She denies any chest pain or SOB. Vital signs are: Temperature = 100.2, BP = 118/68, pulse = 84, RR = 18. Oxygen saturation on room air is 96%. Physical examination is significant only for bruising of her left wrist and thigh. Heart and lung examination is normal. Which of the following is the most likely diagnosis?
Arrhythmia Hint: Cardiovascular causes of syncope include arrhythmias, mechanical heart disease (e.g., aortic stenosis and hypertrophic cardiomyopathy), pulmonary embolism, aortic dissection, and cardiac tamponade. Patients with sudden onset syncope and trauma to the face (indicating an inability to brace the fall) should increase the reader’s suspicion for a cardiac etiology. | |
Orthostatic hypotension Hint: Orthostatic hypotension usually occurs in the presence of hypovolemia, dysautonomia, and/or certain medications (e.g., diuretics and β-blockers). Diagnosis can be made if systolic blood pressure decreases by ≥20 mm Hg or diastolic blood pressure decreases by ≥10 mm Hg when going from a sitting to a standing position, which was not seen in this patient. | |
Seizure Hint: Seizures technically do not meet the definition of syncope, since they are not caused by a disruption in cerebral blood flow. History that would indicate a seizure includes a preceding aura, tonic–clonic movements during the episode, and a postictal state (confusion with gradual improvement in neurologic function). | |
Vasovagal syncope | |
Aortic stenosis Hint: Cardiovascular causes of syncope include arrhythmias, mechanical heart disease (e.g., aortic stenosis and hypertrophic cardiomyopathy), pulmonary embolism, aortic dissection, and cardiac tamponade. Patients with sudden onset syncope and trauma to the face (indicating an inability to brace the fall) should increase the reader’s suspicion for a cardiac etiology. |
Question 1 Explanation:
Vasovagal syncope. Syncope is defined as loss of consciousness that results from cerebral hypoperfusion. The most common cause of syncope is neurocardiogenic (vasovagal) syncope, which is caused by a sudden surge of sympathetic activity that transiently increases the contractility of the left ventricle. Mechanoreceptors in the left ventricle sense this increased contractility and cause an excessive vagal response, which lowers heart rate and contractility. This transiently drops the blood pressure and causes syncope. These patients typically have symptoms of lightheadedness, nausea, and narrowing vision before losing consciousness and can usually brace their fall somewhat. Diagnosis can be made with the tilt table test.
Question 2 |
Which of the following best explains the pathophysiology of vasovagal syncope?
Increase in parasympathetic signals and withdrawal of sympathetic signals | |
Severe narrowing of the aortic valve | |
Drop in blood pressure upon standing due to inadequate peripheral vasoconstriction | |
Occlusion of the pulmonary artery leading to right ventricle dysfunction | |
Blood accumulation in the brain leading to compression of adjacent brain structures |
Question 2 Explanation:
Vasovagal syncope is the most common cause of syncope. Syncope is essentially transient loss of consciousness due to the lack of cerebral perfusion. Vasovagal syncope is usually triggered by something, such as emotion or stress. A leading hypothesis of vasovagal syncope is that it is due to an increase in parasympathetic signals and withdrawal of sympathetic nervous signals.
There are 2 questions to complete.
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References: Merck Manual · UpToDate
