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 conscious) due to transient global cerebral hypo-perfusion characterized by rapid onset, short duration 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

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 by emotion or by orthostatic stress.  It is usually preceded by prodromal symptoms 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 sinuses.  In the more common form no mechanical trigger is found and it is diagnosed by carotid sinus massage

Orthostatic Hypotension  OH is defined as an abnormal decrease in systolic BP upon standing.

Cardiac syncope  Arrhythmic  Structural

Cardiac syncope  Arrhythmias are the most common cardiac causes of syncope.  They induce haemodynamic impairment, which 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 initial evaluation, are more frequent in emergency referrals and reflect the multifactorial complexity of these patients.  The high unexplained syncope rate in all settings justifies new 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 outcomes seem to be related to the severity of the underlying disease rather than to syncope per se.

Recurrence of syncope and risk of physical injury  one-third of patients have recurrence of syncope in 3 years follow-up.  The number of episodes of syncope during life 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 key questions: (1) Is it a syncopal episode or not? (2) Has the aetiological diagnosis been determined? (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 manoeuvres  Tilt training  Pharmacological therapy  Cardiac pacing