SYNCOPE
PAYAD, KAREN A. M.D.
SYNCOPE
◼ Transient , self limited loss of consciousness due to acute
global impairment of cerebral blood flow
◼ Rapid
◼ Brief
◼ Spontaneous and complete recovery
PRESYNCOPE
◼ Dizziness
◼ Lightheadedness/faintness
◼ Weakness
◼ Fatigue
◼ Visual/auditory disturbances
PATHOPHYSIOLOGY
Upright position- pooling of 500–1000 mL of blood in the lower
extremities and splanchnic circulation
decrease in venous return
reduced ventricular filling
diminished cardiac output and blood pressure
PATHOPHYSIOLOGY
compensatory reflex response -baroreceptors (carotid sinus
and aortic arch)
Increased sympathetic outflow
decreased vagal nerve activity
Increases peripheral resistance
venous return and CO
PATHOPHYSIOLOGY
◼ Cerebral blood flow - 50 to 60 mL/min per 100 g brain
tissue
◼ Perfusion pressures ranging from 50 to 150 mmHg
PATHOPHYSIOLOGY
◼ Cessation of blood flow for 6–8 s will result in LOC
◼ impairment of consciousness ensues- blood flow
decreases to 25 mL/min per 100 g brain tissue
CLASSIFICATION
◼ Neurally Mediated Syncope
◼ Orthostatic Hypotension
◼ Cardiac Syncope
NEURALLY MEDIATED SYNCOPE
◼ AKA Reflex or Vasovagal Syncope
◼ Most common
◼ transient change in the reflexes responsible for maintaining
cardiovascular homeostasis
◼ Episodic vasodilation and bradycardia occur in varying
combinations, resulting in temporary failure of blood
pressure control
CLINICAL FEATURES
◼ Orthostatic intolerance
▪ Dizziness, lightheadedness, fatigue
◼ Autonomic activation
▪ diaphoresis, pallor, palpitations, nausea, hyperventilation, and
yawning
◼ Proximal and distal myoclonus
CLINICAL FEATURES
◼ eyes remain open and deviate upward
◼ Pupils are dilated
◼ Grunting, moaning, snorting, and stertorous breathing
◼ Urinary incontinence
◼ Fecal incontinence - very rare
TREATMENT
Cornerstones of the management
◼ Reassurance
◼ Avoidance of provocative stimuli
◼ Plasma volume expansion with fluid and salt
TREATMENT
Isometric counterpressure maneuvers
◼ leg crossing
◼ Handgrip
◼ arm tensing
TREATMENT
◼ Fludrocortisone
◼ Vasoconstricting agents
◼ β-adrenoreceptor antagonists
ORTHOSTATIC HYPOTENSION
◼ reduction in systolic blood pressure of at least 20 mmHg or
diastolic blood pressure of at least 10 mmHg within 3 min of
standing or head-up tilt on a tilt table
◼ is a manifestation of sympathetic vasoconstrictor
(autonomic) failure
ORTHOSTATIC HYPOTENSION
◼ no compensatory increase in heart rate despite
hypotension
◼ partial autonomic failure, heart rate may increase to some
degree but is insufficient to maintain cardiac output
ORTHOSTATIC HYPOTENSION
“Delayed” orthostatic hypotension
▪ occurs beyond 3 min of standing reflects a mild or early form
of sympathetic adrenergic dysfunction
“Initial” orthostatic hypotension
▪ hypotension occurs within 15 s of standing
▪ may reflect a transient mismatch between cardiac output and
peripheral vascular resistance and does not represent
autonomic failure
CHARACTERISTIC SYMPTOMS
◼ light-headedness, dizziness, and presyncope
◼ generalized weakness, fatigue, cognitive slowing, leg
buckling, or headache
◼ Visual blurring
◼ Neck pain
▪ suboccipital, posterior cervical, and shoulder region (the “coat-
hanger headache”)
◼ Orthostatic dyspnea
◼ Angina
TREATMENT
◼ remove reversible causes
◼ Nonpharmacologic interventions
▪ patient education: staged moves from supine to upright
▪ warnings : hypotensive effects of large meals
▪ Instructions: isometric counterpressure maneuvers
▪ raising the head of the bed to reduce supine hypertension
◼ Intravascular volume expansion
TREATMENT
◼ Pharmacologic intervention
▪ fludrocortisone acetate
▪ Midodrine
▪ L-dihydroxyphenylserine
▪ Pseudoephedrine
◼ Intractable
▪ Pyridostigmine
▪ atomoxetine,
▪ yohimbine,
▪ desmopressin acetate (DDAVP)
▪ erythropoietin
CARDIAC SYNCOPE
◼ caused by arrhythmias and structural heart disease
TREATMENT
◼ Cardiac pacing
◼ Ablation
◼ Antiarrhythmic drugs
◼ Cardioverter-defibrillators
APPROACH TO PATIENT WITH
SYNCOPE
◼ Initial Evaluation
▪ Detailed history
▪ Thorough questioning of eyewitnesses
▪ Complete physical and neurologic examination
◼ Laboratory tests
◼ Tilt-table testing
◼ Carotid Sinus Massage
◼ Cardiac Evaluation
▪ ECG
▪ Holter Monitoring
▪ Echocardiography
▪ Treatmill Exercise Testing
◼ Psychiatric Evaluation
