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Syncope – Causes, Diagnosis


syncope arterial hypotensionSyncope is manifested clinically by transient loss of consciousness caused by global cerebral hypoperfusion and is characterized by sudden tripping with short duration and total spontaneous recovery.

Faintness is characterized by malaise, without loss of consciousness. Sometimes to be considered as a transient loss of consciousness of short duration it is accompanied by post critical amnesia.

Pathophysiology – motivation

Syncope is the result of an acute or sub-acute cerebral ischemia as a result of respiratory arrest or sudden decrease in blood pressure or a transient hypoxia.

Three mechanisms have a decisive character:

1. Reflex Syncope (with nervous character)

Vasovagal: – Triggered by emotional stress: fear, pain, surgical maneuvers, fear of blood;

     – Triggered by orthostatism.

Situations: – Coughing, sneezing;

     – gastrointestinal stimulation;

     – Micturition;

     – Post-exercise;

     – Post-prandial;

     – Other conditions: emotions, lifting weights, efforts for singers with blowing instruments

Syncope through hypersensitivity of carotid sinus.

Reflex Syncope

2. Syncope due to orthostatic hypotension

Nervous primary dysautonomia:

  • Isolated dysautonomia, nerve atrophy caused by systemic disease;

  • Parkinson nervous autonomic dysfunction, dementia with lewy bodies.

Nervous secondary dysautonomia:

  • Diabetes, amyloidosis, uremia, spinal cord injuries.

Drug-induced orthostatic hypotension:

  • Alcohol, vasodilators, diuretics, phenothiazines, antidepressants.


  • Post-bleeding, diarrhea, vomiting, etc.

3. Cardiac arrhythmic syncope:

Bradycardia: – Sinus node disease;

        – Atrioventricular conduction disturbances;

        – Pacemaker malfunctions.

Tachycardia: – Supraventricular

        – Ventricular

        – ICD – Malfunctions


A more pronounced manifestation of syncope and faintness occurs in people between 10 and 30 years at a rate of 47% in women and 31% in men with the most common cause the vasovagal mechanism. The second peak of incidence occurs in people aged more than 65 years in both women and men and reflex syncope is the most common mechanism.

Orthostatic hypotension is rare, being more common in the elderly.

Clinical diagnosis of Syncope

Typical syncope is characterized by: sudden onset, it is not preceded by prodromal symptoms, is accompanied by trauma, rapid recovery, the patient presents amnesia after the crisis.

Manifestation: – the patient is pale with muscular hypotonia, abnormal movements and without any loss of urine or bite of the tongue, unless when anoxia is prolonged.

Atypical Syncope (frequent) is characterized by: sweating, vertigo, visual disturbances, accompanied by seizures, biting of the tongue, loss of urine and loss of consciousness more than 30 seconds.

Percritic exam – abnormal heart rhythm, pupils state, convulsions, presence of cyanosis. Long-term loss of consciousness will proceed with resuscitation maneuvers.

Examination postcritic – the patient recovered and in this phase is examined: circumstances in which the accident occurred, the duration of loss of consciousness, if the patient has other diseases like diabetes, alcohol consumption or toxic substances (drugs).

Complete physical examination – cardiovascular and neurological examination, palpation and listening to vessels murmurs (carotids), search of a sensory deficit.

Syncope Etiological Diagnosis

Circumstances preceding syncope: patient position (sitting or standing); the work done by the patient (forerunner such as: position changes, effort, urine, etc.); predisposing factors or precipitating states. (Such as: heat, crowds, fear, and pain).

Manifestations during onset of syncope: nausea, vomiting, abdominal discomfort, feeling of sweat, pain in the neck or shoulders, blurred vision, dizziness, palpitations.

During Syncope: falling by kneeling or collapse, skin color, the duration of loss of consciousness, breathing mode, movements and duration of movements, bite of the tongue.

The end of syncope episode: nausea, vomiting, abdominal discomfort, feeling cold, sweating, muscle aches, skin color, chest pain, palpitations, urinary or faecal incontinence, trauma.

A history of the patient: family members with cardiac diseases, neurologic disorders, metabolic disorders, alcohol or drugs consumption.

Laboratory tests: To do a physical exam, including measurement of blood pressure in orthostatic position, an electrocardiogram and the following diagnostic tests: 1. Echocardiography; 2. Carotid sinus massage; 3. Orthostatic test; 4. tilt test; 5. Electrocardiographic monitoring; 6. Effort test; 7. Electrophysiological study; 8. Cardiac catheterization; 9. Psychiatric evaluation; 10. Neurological evaluation.

Diagnostic criteria for initial evaluation

Vasovagal syncope: is precipitated by emotional stress or prolonged orthostatism and is associated with typical prodromal symptoms.

Situational syncope – occurs during or after the triggering factors.

Syncope orthostatic – occurs after orthostatism with documentation about orthostatic hypotension.

Syncope in relation with arrhythmia is diagnosed by ECG:

  • persistent sinus bradycardia <40 bpm or repetitive sinoatrial block;

  • sinus pauses >  or equal of 3s;

  • second degree AV block type II or grade III Mobitz;

  • alternate branch block;

  • TV or fast TSV;

  • TV episodes and long or short QT interval;

  • dysfunction of pacemaker or ICD with cardiac pause

Syncope in relation to ischemic heart disease – is accompanied by ECG evidence of acute ischemia with or without myocardial infarction.

Cardiovascular syncope occurs in patients with prolabant atrial myxoma, severe aortic stenosis, pulmonary hypertension, pulmonary embolism and acute aortic dissection.

Differential diagnosis – are considered two types of conditions

  1. Affections with loss of consciousness, partial or total, without global cerebral hypoperfusion:  epilepsy, metabolic disorders (including hypoglycemia, hypoxia, hyperventilation or hypercapnia); intoxication; carotid transient ischemic episode.

  2. Affections without impaired consciousness: Cataplexy; drop attacks (minor stroke); fainting; psychogenic pseudo-syncope; carotid transient ischemic episode.

Risk criteria

  • Coronary artery disease or severe heart disease;

  • Clinical aspects and ECG suggesting arrhythmogenic syncope: During exercise; palpitations during the syncope; family history of sudden death; ventricular tachycardia with duration less than 30 seconds; bifascicular block (intraventricular conduction abnormalities with QRS duration>= 120 ms); sinus bradycardia (<50 bpm); complex QRS with pre-excitation; long or short QT intervals; appearance of right bundle branch block with ST elevation in leads V1-V3; negativity of the T wave in the right precordial leads.

  • Comorbidities: severe anemia and electrolyte disorders.

Syncope treatment – the knowledge of the case ensures appropriate treatment key

Emergency treatment – emergency kit: The monitor, portable electrocardiograph or portable defibrillator that can record heart rate, give electric shocks and can achieve a transient external stimulation.

Injectable drugs – atropine, isoprenaline, epinephrine, lidocaine, metoprolol, and glucose, saline solution.

Etiological treatment.

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