CHAPTER 18 SYNCOPE Flashcards
it is the transient self limited self conscious due to acute global impairment of cerebral blood flow
syncope
onset of syncope
rapid duration brief and recovery spontaneous
differential diagnosis for syncope
seizures
vertebrobasilar ischemia
hypoxemia
hypoglycemia
what is the typical presyncope (syncopal prodrome)
dizziness lightheadednes faintess weakness fatigue visual and auditory distrubances
causes of syncope
neurally mediated syncope also called for reflex or vasovagal syncope
orthostatic hypotension
cardiac syncope
type of syncope that comprises heterogenous group of functional disorders that is characterized by transient change in the reflexes responsible for maintaining cardiovascular homeostasis
neurally mediate syncope
causes for the temporary failure of blood pressure control
episodic vasodilation (loss of vasoconstrictor tone)
cause of orthostatic hypotension
autonomic failure where the cardiovascular homeostatic reflexes are chronically impaired
causes of cardiac syncope
arrhythmias or structural cardiac disease that can cause a decrease in cardiac output
what is peak incidence of syncope
age 10 to 30 years
gender prevalence of syncope
females than in males
pathophysiology of syncope
standing-pooling of blood in lower extremities-decrease in venous return to the heart-reduced ventricular filling-result to diminished cardiac output and blood pressure
the decreased cardiac output will activate the
compensatory reflex response initiated by the baroreceptors in the carotid sinus and aortic arch resulting to increased sympathetic outflow and decreased vagal nerve activity
the reflex will result to:
increased peripheral resistance, venous return to the heart, cardiac output thus limits the fall in the blood pressure
if the response fails?
chronic: orthostatic hypotension
transient: neurally mediated syncope
leading to cerebral hypoperfusion
responsible for autoregulation of cerebral blood flow
myogenic factors
local metabolites
autonomic neurovascular control
how many minutes cessation of blood from the brain will result to loss of consciousness
6-8 seconds
bp that will result to syncope
a fall in systolic blood pressure of 50 or lower
causes of decreased cardiac output
decreased effective circulating blood increased thoracic pressure massive pulmonary embolus cardiac brady and tachyarrhythmias valvular heart disease myocardial dysfunction
what are the two patterns of EEG changes in syncopal subjects
slow flat slow pattern followed by sudden flattening of the EEG followed by the return of slow waves and then normal activity
slow pattern characterized by increasing and decreasing slow wave activity
cause of flattening pattern
cessation or attenuation of cortical activity
this type of syncope is the final pathway of a complex central and peripheral nervous system reflex arc where is sudden transient change in autonomic efferent activity with increased parasympathetic outflow resulting in bradycardia, vasodilatation and reduced constriction tone
neurally mediated syncope
subtypes of neurally mediated syncope based on afferent pathway
vasovagal syncope and situational reflex syncope
another term for vasovagal syncope
common faint
common faint is provoked by
intense emotion
pain
orthostatic stress
cause of situational reflex syncope
specific localized stimuli that provoke the reflex vasodilation and bradycardia that leads to syncope
the subtypes of efferent syncope
vasodepressor syncope and cardioinhibitory syncope and mixed syncope
features of neurally mediated syncope
orthostatic intolerance dizziness lightheadedness fatigue premonitory features of autonomic activation: pallor, diaphoresis, palpitations, nausea, hyperventilation, and yawning
features during the attack
proximal and distal myoclonus- possibility of epilepsy eyes open and deviate upward pupils are dilated roving eye movement grunting moaning snorting stertous breathing urinary incontinence fecal incontinence postictal confusio visual and auditory hallucination
predisposing factor of neurally mediated syncope
motionless upward posture warm ambiance temperature intravascular volume depletion alcohol ingestion hypoxemia anemia pain sight of blood venipuncture intense emotion
cornerstone treatment for neurally mediate syncope
reassurance
avoidance of proactive stimuli
plasma volume expansion with fluid and salt
how to raise blood pressure by increasing blood central volume and cardiac output
isometric counterpressure maneuvers of limbs such as leg crossing or handgrip and arm tensing
pharmacotherapy for neurally mediated syncope
fludrocortisone
vasoconstricting agents
beta adrenenoreceptor antagonist
when is cardiac pacemaker used
older px >40 years old in which the syncope is associated with asystole or severe bradycardia and in patients with prominent cardioinhibition due to carotid sinus syndrome
type of syncope that is defined as reduction in systolic blood pressure of at least 20mmHg or diastolic blood pressure of at least 10 mmHg within 3 minutes of standing or head tilt up
orthostatic hypotension
variant of orthostatic syncope that hypotension is delayed which occurs beyond 3 mins of standing
mild or early form of sympathetic adrenergic dysfunction
a variant of orthostatic syncope where hypotension occurs within 15 seconds of standing that reflect a transient mismatch between cardiac output and peripheral vascular resistance and it does not represent autonomic failure
initial orthostatic hypotension
features of orthostatic hypotension
light headedness dizziness presyncope (near faintness) nonspecific: general weakness, fatigue, cognitive slowing, leg buckling or headache visual blurring neck pain dyspnea angina
cause of visual disturbance
retinal and occipital lobe ischemia
location of neck pain
suboccipital
posterior cervical
shoulder region (the coat hanger headache)
cause of dyspnea
ventilation-perfusion mismatch due to inadequate perfusion of ventilated lung apicess
cause of agina
impaired myocardial perfusion even with normal coronary arteries
aggravating factors for symptoms
exertion
prolonged standing
increased ambient temperature or meals
causes of neurogenic orthostatic hypotension
central and peripheral autonomic nervous system dysfunction
drugs that can cause orthostatic hypotension
alpha adrenoreceptor antagonists antihypertensive nitrates vasodilators tricyclic agents phenothiazines
first step of treatment for orthostatic hypotension
remove the reversible causes such as vasoactive medications
second step in treatment of orthostatic hypotension
nonpharmacologic interventions such as patient education regarding staged moves from supine to upright
warnings about the hypotensive effects of large meals
pharmacologic intervention for orthostatic hypotension
fludrocortisone acetate
vasoconstricting agents
cause of cardiac syncope
arrhythmias and structural heart disease
bradyarrhythmias that can cause syncope includes
sinus node dysfunction such as sinus arrest or sinoatrial block
atrioventricular block
most common association of bradyarrhythmias due to sinus node dysfuction
atrial tacyarrhythmia known as tachycardia-bradycardia syndrome
syncope due to bradycardia or asytole is referred as
strokes-adams attack
cause of the compromised hemodynamic function during ventricular tachycardia
infective ventricular contraction
the long QT syndrome that is associated with prolonged cardiac repolarization and a predisposition to ventricular arrhythmias
torsades de pointes
it is a inherited associated with exercise stress induced ventricular arrhythmias syncope or sudden death
catecholaminergic polymorphic tachycardia
treatmen for cardiac syncope caused by arrythmias
cardiac pacing for sinus node
AV block and ablation-antiarrhytmic drugs and cardioverter defibrillators
type of seizure present in syncope
myoclonic-generalized or multifocal
reorientation from drowsiness in syncope
occurs immediately after the syncopal event
syncope are provoked by emotions unlike seizures
true
