Syncope and Autonomic Disorders Flashcards

What is the most common type of syncope in the general population?

Answer: Vasovagal syncope

Vasovagal (neurally mediated) syncope accounts for approximately 50% of all syncope cases and is the most prevalent form.

Orthostatic hypotension is defined as a sustained reduction in systolic blood pressure of at least how many mmHg within 3 minutes of standing?

Answer: 20 mmHg

Orthostatic hypotension requires a drop of ≥20 mmHg in systolic BP or ≥10 mmHg in diastolic BP within 3 minutes of standing.

The cardioinhibitory type of vasovagal syncope is primarily characterized by:

Answer: Significant bradycardia or asystole with minimal hypotension

Cardioinhibitory vasovagal syncope is defined by predominant bradycardia or asystole with relatively preserved blood pressure until near loss of consciousness.

Carotid sinus hypersensitivity is diagnosed when carotid sinus massage produces a ventricular pause of at least:

Answer: 3 seconds

A ventricular pause of ≥3 seconds during carotid sinus massage defines the cardioinhibitory form of carotid sinus hypersensitivity.

POTS (Postural Orthostatic Tachycardia Syndrome) is defined by a heart rate increase of at least how many beats per minute upon standing within 10 minutes, without orthostatic hypotension?

Answer: 30 bpm

POTS requires an increase in heart rate of ≥30 bpm (or HR ≥120 bpm) within 10 minutes of standing without a concurrent drop in blood pressure ≥20 mmHg.

Which alpha-1 adrenergic agonist is used to treat neurally mediated syncope and orthostatic hypotension by increasing peripheral vascular resistance?

Answer: Midodrine

Midodrine is a selective alpha-1 agonist that raises peripheral vascular resistance and venous return, reducing syncope recurrence and has a Class IIa recommendation for vasovagal syncope.

The vasodepressor type of vasovagal syncope is primarily characterized by:

Answer: Hypotension with little or no bradycardia

Vasodepressor syncope is defined by predominant hypotension due to peripheral vasodilation, with heart rate decreasing by less than 10% of peak value.

In the VASIS (Vasovagal Syncope International Study) classification, Type 2B vasovagal syncope is characterized by:

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.

The standard tilt table test is typically performed at what upright angle?

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.

Fludrocortisone reduces syncope primarily by:

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.

Syncope occurring during exercise in a young patient should raise concern for which underlying condition?

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.

The autonomic response in vasovagal syncope involves activation of which reflex?

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.

On an implantable loop recorder (ILR) in a patient with recurrent syncope, which finding best supports a neurally mediated (vasovagal) mechanism?

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.

POTS is most commonly seen in which demographic group?

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.

Which of the following is an example of situational reflex syncope?

Answer: Micturition syncope

Micturition syncope is a form of situational reflex syncope triggered by specific physiological acts such as urination, defecation, coughing, or swallowing.

An implantable loop recorder (ILR) is most appropriately indicated for:

Answer: Patients with recurrent unexplained syncope after a complete initial evaluation

ILR is indicated for unexplained recurrent syncope where standard non-invasive tests have been inconclusive, allowing long-term ECG monitoring during spontaneous episodes.

Neurogenic orthostatic hypotension is commonly associated with which of the following conditions?

Answer: Parkinson's disease

Parkinson's disease and related synucleinopathies (e.g., multiple system atrophy) cause central and peripheral autonomic neurodegeneration, leading to neurogenic orthostatic hypotension.

The EGSYS (Evaluation of Guidelines in Syncope Study) score is primarily used to:

Answer: Predict the probability of a cardiac (arrhythmic) cause of syncope

The EGSYS score uses clinical variables (palpitations, ECG abnormalities, structural heart disease, absence of vagal triggers) to predict the likelihood of cardiac syncope and guide risk stratification.

Physical counterpressure maneuvers (PCMs) such as leg crossing with muscle tensing and handgrip are recommended as first-line treatment for:

Answer: Prodromal vasovagal syncope with warning symptoms

PCMs increase venous return and cardiac output during the prodromal phase of vasovagal syncope, aborting or delaying the syncopal episode without pharmacologic side effects.

An HV interval of 70 ms or greater found during an electrophysiology study in a syncope patient is significant because it indicates:

Answer: Significant infranodal conduction disease increasing risk of high-degree AV block

An HV interval ≥70 ms reflects markedly prolonged His-Purkinje conduction and is a strong predictor of spontaneous high-degree or complete AV block, guiding pacemaker implantation.