From the Guidelines
Syncope is a symptom that presents with an abrupt, transient, complete loss of consciousness, associated with inability to maintain postural tone, with rapid and spontaneous recovery, as defined by the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society 1.
Definition and Classification
The definition of syncope is based on the presumed mechanism of cerebral hypoperfusion, and it should not be confused with other nonsyncope causes of loss of consciousness, such as seizure, antecedent head trauma, or apparent loss of consciousness (i.e., pseudosyncope) 1.
- Syncope is characterized by a sudden loss of consciousness, typically lasting only a few seconds to minutes.
- The condition results from a temporary drop in blood pressure, heart rate, or blood oxygen levels that reduces cerebral perfusion.
- Common triggers include standing for long periods, dehydration, emotional stress, pain, or certain medical conditions affecting the heart or nervous system.
Key Features and Diagnosis
Before fainting, a person may experience warning signs called prodromal symptoms, including:
- Lightheadedness
- Nausea
- Sweating
- Ringing in the ears
- Visual disturbances The diagnosis of syncope is made primarily on the basis of a thorough history, physical examination, and eyewitness observation, if available 1.
Importance of Evaluation
Proper evaluation is important to distinguish between benign causes and potentially life-threatening conditions, such as underlying cardiovascular problems like arrhythmias or structural heart disease 1.
- Most episodes of syncope are benign, especially vasovagal syncope triggered by emotional stress or pain.
- However, some cases may indicate serious underlying conditions that require prompt medical attention.
From the Research
Definition of Syncope
- Syncope is defined as transient loss of consciousness due to global cerebral hypoperfusion 2
- It is characterized by having a relatively rapid onset, brief duration with spontaneous and full recovery 2
- The condition is often caused by a temporary reduction in blood flow to the brain, which can be triggered by various factors, including cardiac issues, reflex (neurally mediated) syncope, and orthostatic hypotension 3, 2
Key Characteristics
- Syncope has a rapid onset and brief duration, with most patients experiencing a full recovery 2
- The condition can be caused by cardiac syncope, reflex syncope, or orthostatic hypotension, each with distinct mechanisms and treatment approaches 3
- A thorough history and physical examination, including orthostatic assessment, are crucial for making an accurate diagnosis 2
Diagnosis and Treatment
- The first step in diagnosing syncope is to identify patients with cardiac syncope, who require mechanism-specific treatment 3
- For non-cardiac syncope, reflex (neurally mediated) syncope and orthostatic hypotension are the most frequent causes, and treatment efficacy is largely determined by the underlying mechanism 3
- Established treatment strategies include withdrawal of hypotensive drugs, applying fludrocortisone and midodrine for the hypotensive phenotype, and cardiac pacing in the bradycardic phenotype 3