晕 厥 -syncope 浙江大学医学院附属第二医院 心内科 项美香. definition syncope is...
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晕 厥 -Syncope
浙江大学医学院附属第二医院
心内科 项美香
Definition
Syncope is a T-LOC (transient loss of consci
ous) due to transient global cerebral hypo-perfu
sion characterized by rapid onset, short durati
on and spontaneous complete recovery.
Mechanism
Global cerebral hypo-perfusion Blood pressure which determined by
Cardiac output
peripheral vascular resistance
Classification
Cardiac syncope Reflex syncope Orthostatic syncope
Classification of syncope
Classification of syncope
Classification of syncope
Reflex syncope
Reflex syncope is usually classified as Cardiac-inhibitory Vasodepressor Mixed
Reflex syncope may also be classified based on its trigger
Vasovagal’ syncope (VVS)
known as the ‘common faint’, is mediated b
y emotion or by orthostatic stress.
It is usually preceded by prodromal sympto
ms of autonomic activation (sweating, pallor,
nausea).
Situational’ syncope traditionally refers to reflex syncope associated
with some specific circumstances.
Post-exercise syncope can occur in young
athletes as a form of reflex syncope as well as in
middle-aged and elderly subjects as an early
manifestation of ANF before they experience
typical OH.
Carotid sinus’ syncope
In its rare spontaneous form it is triggered by
mechanical manipulation of the carotid sinus
es.
In the more common form no mechanical trig
ger is found and it is diagnosed by carotid si
nus massage
Orthostatic Hypotension
OH is defined as an abnormal decrease in s
ystolic BP upon standing.
Cardiac syncope
Arrhythmic
Structural
Cardiac syncope
Arrhythmias are the most common cardiac c
auses of syncope.
They induce haemodynamic impairment, wh
ich can cause a critical decrease in CO and
cerebral blood flow.
Cardiac syncope
Bradycardia Tachycardia
Cardiac syncope
Structural disease Cardiac valvalar disease Hypertrophic cardiomyopathy Atrial myxoma Pericardial disease /tanponade Acute aortic dissection Pulmonary hypertension or embolus
Prevalence of the causes of syncope
Reflex syncope is the most frequent cause of
syncope in any setting.
Syncope secondary to cardiovascular disease is
the second most common cause.
Higher frequencies are observed in emergency
settings mainly in older subjects, and in settings
oriented toward cardiology.
Prevalence of the causes of syncope
In patients <40 years , OH is a rare cause of syncope;
OH is frequent in very old patients.
Non-syncopal conditions, misdiagnosed as syncope at initi
al evaluation, are more frequent in emergency referrals and
reflect the multifactorial complexity of these patients.
The high unexplained syncope rate in all settings justifies n
ew strategies for evaluation and diagnosis
Prognosis
two important elements should be considered:
risk of death and life-threatening events;
risk of recurrence of syncope and physical injury.
The structural heart disease and primary electrical
disease are the major risk of SCD
Prognosis
Most of the deaths and many poor outcome
s seem to be related to the severity of the un
derlying disease rather than to syncope per
se.
Recurrence of syncope and riskof physical injury
one-third of patients have recurrence of syn
cope in 3 years follow-up.
The number of episodes of syncope during li
fe is the strongest predictor of recurrence.
Diagnosis History Physical examination Orthostatic BP measurement Relative examination
Tilt table testing Echo EP others
Diagnosis The initial evaluation should answer three ke
y questions:
(1) Is it a syncopal episode or not?
(2) Has the aetiological diagnosis been deter
mined?
(3) Are there data suggestive of a high risk of
cardiovascular events or death?
Treatment
Goal: to prolong survival, limit physical
injuries, and prevent recurrences.
the cause of syncope has a key role in
selection of treatment.
Treatment of reflex syncope
Patient education Lifestyle: physical counter-pressure manoeuvr
es Tilt training Pharmacological therapy Cardiac pacing