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