Exertional syncope

Introduction Labor syncope suggests a cardiac outflow obstruction, mainly due to aortic stenosis. This syncope reflects cerebral ischemia caused by the simultaneous expansion of peripheral blood vessels due to the inability to increase cardiac output due to labor. Prolonged syncope can cause seizures. Low blood volume and positive inotropic drugs (such as digitalis) can aggravate outflow obstruction in patients with hypertrophic obstructive cardiomyopathy, and sudden syncope may occur. Syncope often occurs immediately after exercise because of reduced venous return, decreased left atrial pressure, and reduced ventricular filling. Arrhythmia may also be a contributing factor. Functional abnormalities after heart valve replacement may also be the cause. Labor syncope may also cause outflow obstruction due to other causes (such as pulmonary vascular occlusion or pulmonary hypertension caused by pulmonary embolism), and left ventricular filling or pericardial tamponade due to decreased left ventricular compliance, or venous return obstruction ( Such as severe pulmonary hypertension or tricuspid stenosis, caused by intracardiac myxoma. Myxoma can cause orthostatic syncope because the pedicled left atrial myxoma blocks the mitral valve opening. Coughing and urination can cause venous return to reduce syncope, and syncope can also occur when doing Valsalva action. The increase in intrathoracic pressure limits venous return, which reduces cardiac output and decreases systemic arterial pressure.

Cause

1. Cardiac outflow obstruction, aortic stenosis.

2. Reduced venous return, decreased left atrial pressure and decreased ventricular filling.

3. Functional abnormalities after heart valve replacement may also be the cause.

4. Outflow obstruction caused by other causes (such as pulmonary vascular occlusion caused by pulmonary embolism or pulmonary hypertension), and left ventricular filling or pericardial tamponade due to decreased left ventricular compliance, or venous return obstruction (such as severe pulmonary artery) High pressure or tricuspid stenosis, intracardiac myxoma).

an examination

Syncope is a group of clinical manifestations of sudden, transient loss of consciousness and loss of control caused by various causes, and self-recovery. Typical syncope episodes are transient and the loss of consciousness rarely exceeds 20-30 seconds. Before the onset of partial syncope, there are prodromal symptoms such as dizziness, tinnitus, sweating, blurred vision, pale complexion, and general malaise. This period is called the prodromal period. Symptoms such as fatigue, nausea, vomiting, lethargy, and even incontinence after the onset are called recovery periods. Therefore, the entire process of syncope may last for a few minutes or longer. Syncope usually does not produce retrograde forgetting, and the orientation and correct behavior often recover quickly.

Labor syncope often occurs immediately after exercise, and prolonged syncope can cause seizures.

Differential diagnosis

(a) Reflective syncope

1, simple syncope: also known as vasovagal syncope, vascular decompression syncope. Clinically more common, there are obvious incentives before fainting, such as pain, high temperature, nervousness, fear, emotional, poor ventilation, air pollution, fatigue, persistent standing, hunger, pregnancy and the late stages of various chronic diseases. The pre-syncope period is relatively short, usually 15-30s. If you immediately lie flat in this period, the prodromal symptoms disappear, and the prodromal symptoms are mostly dizziness, nausea, paleness, sweating and so on. The performance of syncope is also temporary. It lasts for 30s to 2-3min. It is characterized by loss of consciousness, paleness, weakness of limbs, decreased blood pressure, slow heart rate, weak pupil, dilated pupils, and disappearance of light response. Whether there is urinary incontinence, limb convulsions, biting the tongue, etc. Symptoms of late syncope may have transient weakness or dizziness, etc., generally recover faster, no obvious aftereffects.

Should pay attention to the identification of epilepsy, rickets and dizziness. In the case of seizures, there are no obvious prodromal symptoms, and there is a loss of consciousness during the attack. There may be urinary incontinence, limb convulsions, biting the tongue, etc. EEG and brain CT or MRI are abnormally found. There are obvious mental stimuli during the onset of rickets, and the attack lasts for a long time. When the attack occurs, it disappears unconsciously and responds to people and things around. There is no obvious cause before vertigo, and vertigo is a kind of illusion of movement or movement. The patient feels that the external environment or itself is rotating, moving or shaking, which is caused by vestibular nervous system lesions.

2, upright hypotonic syncope

When the patient changes from a supine position to an upright position, the blood pressure drops rapidly and the cerebral blood flow is insufficient. When the symptoms of syncope appear, it is called orthostatic hypotension.

Cause: The cause is unknown. At present, the possible factors or theories are:

(1) A degenerative disease that originates in the central nervous system or the surrounding autonomic nervous system, resulting in dysfunction of the central or peripheral autonomic nervous system.

(2) Defects in the conduction function of the body, resulting in insufficient synthesis of norepinephrine.

(3) Metabolic disorders of catecholamines form the basis of autonomic and extrapyramidal diseases, while dopamine decarboxylase and homovanillic acid are also found to be reduced.

(4) The baroreceptor in the lower limb and visceral blood vessel wall reacts abnormally, so that the small arterial reflex contraction disorder and the venous return decrease occur during standing.

Pathological manifestations: multiple degeneration and atrophy of the nervous system, or degeneration of the autonomic ganglia, lateral horn cells of the spinal cord, brain stem, cerebellum, cortex, basal ganglia, especially the dorsal and substantia nigra of the putamen The caudal end, the blue nucleus, the lower nucleus, and the dorsal vagus nucleus become distinct.

Clinical manifestations: more than in the middle age, more men than women. The onset of illness can be from several months to several years, and the elderly can reach more than 10 years. In the early stage, there are only mild symptoms of autonomic dysfunction. After slow progress, the following symptoms may occur: (1) Orthostatic hypotension: when standing for too long, dizziness, blurred vision, transient darkness, and even syncope may occur. It can also trip. Sudden onset, no change in heart rate, recovered in a few seconds or 1-2 minutes. The patient's blood pressure was normal in the supine position, and there was also higher than normal. The blood pressure decreased significantly when standing up, and the decrease range was 4.0-6.7 kPa (30-50) mmHg). In severe cases, whenever you change to an upright position, your blood pressure drops rapidly and syncope occurs. The cause of orthostatic hypotension may be due to the lesion of the autonomic nerve center, blocking the reflex arc of the baroreceptor, and the disorder of peripheral autonomic function. (2) autonomic symptoms: common impotence, menstrual disorders, local or systemic sweating abnormalities. Sphincter disorders such as frequent urination, urgency, urinary retention or incontinence, constipation or stubborn diarrhea. Body temperature fluctuations, or with the Horner sign, advanced patients often have respiratory disorders or even respiratory arrest. (3) Somatic neurological symptoms: often have unclear speech, nystagmus, ataxia and other cerebellar signs; muscle toughness, static card tremor, less activity, mask face, panic gait and other Parkinson-like symptoms; hyperreflexia, pathology Cone beam signs such as reflex positive, and other signs of neurological damage such as cranial nerve palsy, muscle atrophy, dementia, iris atrophy, and hoarseness.

Auxiliary examination: (1) The standing and standing blood pressure usually decreases by 4.0-6.7 kPa (30-50 mmHg). (2) bladder pressure measurement, no tension type. (3) Cerebrospinal fluid examination is normal. (4) EMG can be seen in the fibrillation and tremor potential, and the nerve conduction velocity in the lower limbs is reduced. (5) Head CT common cerebellar hemisphere or ankle and midbrain, pons atrophy, fourth ventricle enlargement, some cortical atrophy and lateral ventricle enlargement.

Diagnosis: There may be a history of syncope in the medical history at night or during the day of getting up or standing for a long time. The blood pressure drop in the supine position and the upright position is 4.0-6.7 kPa (30-50 mmHg) or more, and there are corresponding clinical symptoms, and the secondary blood pressure reduction caused by drugs can be excluded, and often accompanied by impotence, No sweat and bladder rectal dysfunction, or with extrapyramidal dysfunction.

3, urinary syncope: urinary syncope occurs in urination, or at the end of urination, causing decreased blood pressure and syncope. It most often occurs when the patient wakes up at midnight to urinate, and can also occur when urinating in the morning or in the nap.

4, carotid sinus syncope, also known as carotid sinus syndrome, is due to carotid artery stimulation, carotid atherosclerosis or its adjacent lesions, when the collar is too tight. Such as carotid sinus near the tumor, inflammation, trauma, traction or compression of the carotid sinus by external forces, etc. lead to carotid sinus syncope. Clinically, it can be artificially vain type: there is reflex sinus bradycardia, or atrioventricular block; 2 decompression type: mainly showing a significant decrease in blood pressure; 3 central type: mainly manifested as syncope, and blood pressure and heart rate The performance is not obvious. When the carotid sinus pressure test is performed clinically, the heart rate may be slowed down or the blood pressure may be lowered or the syncope may be caused.

5, supine hypotension syncope: mainly seen in the late stage of pregnancy, abdominal tumors, thrombophlebitis, inferior vena cava aponeurosis obstruction and venous primary leiomyoma. The main manifestations are: sudden drop in blood pressure, increased heart rate and syncope during supine. The mechanism is mainly due to the mechanical compression of the inferior vena cava by the mass, which causes the blood in the heart to suddenly decrease and is strange.

(2) Cardiac syncope

Cardiac syncope is mainly caused by cardiac arrest, severe arrhythmia, myocardial ischemia, etc., which causes a sudden drop in blood output from the heart, and a lack of blood supply to the face causes syncope. Onset when standing upright, no obvious signs of aura are more suggestive of cardiac syncope or orthostatic hypotonic syncope. If the syncope in the supine position is more likely to be cardiogenic syncope.

The main causes of cardiogenic syncope are:

1, arrhythmia such as paroxysmal tachycardia, seen in rheumatic heart disease, coronary atherosclerotic heart disease, pulmonary heart disease, hyperthyroidism and pre-excitation syndrome and bradycardia - Overspeed syndrome, etc.

2, sick sinus syndrome and conduction block seen in coronary heart disease, myocarditis, pericarditis, tumor invasion and heart, after atrial septal repair and may damage the operation of the sinus node; conduction block is mainly complete room When the block is blocked, or when a drug that causes a block is applied, such as lidocaine, quinine, or beta blocker.

3, cardiogenic cerebral ischemic syndrome is common in patients with heart disease such as: coronary heart disease, congenital heart disease, conduction block, rheumatic heart disease, myocarditis, vagus reflex.

4, congenital heart disease such as tetralogy of Faro, pulmonary hypertension, patent ductus arteriosus. And primary pulmonary hypertension and left atrial myxoma and left atrial thrombosis can lead to a sudden decrease in cardiac output, acute cerebral vascular insufficiency caused by syncope.

Electrocardiogram, cardiac B-ultrasound, cardiac angiography and other examinations can confirm the diagnosis.

(C) brain-derived syncope

1. Syncope caused by insufficient blood supply to the brain: Hypertension, hypertoxicity of pregnancy, and glomerulonephritis may cause a sudden rise in blood pressure, sudden headache, vomiting, and even syncope, generalized convulsions, and signs of nervous system localization. High intracranial pressure syndrome and other manifestations. Brain-borne syncope is generally longer in causing syncope. Patients with cerebral vascular stenosis can also cause local cerebral insufficiency leading to syncope. When syncope occurs, blood pressure drops and blood flow is slow, which may lead to cerebral thrombosis.

2, the brain tissue itself caused by the disease of syncope: mainly affects the brain stem vascular movement center, the attack time can be longer, the prognosis is not good. Mainly found in: brain stem tumors, symptoms, degeneration, high spinal cord disease.

3, other drugs such as sedatives, tranquilizers, anesthetics, etc. can inhibit central nervous system vasomotor center leading to syncope.

(4) Others

Because of the many causes of syncope, different causes are called different syncopes, such as swallowing syncope, various brain vascular diseases caused by insufficient blood supply to the brain, syncope of the nerve tissue itself, and intracranial damage caused by syncope, etc. Such as hyperventilation syncope, hypoglycemic syncope, severe anemia syncope, crying most embarrassing.

Syncope is a group of clinical manifestations of sudden, transient loss of consciousness and loss of control caused by various causes, and self-recovery. Typical syncope episodes are transient and the loss of consciousness rarely exceeds 20-30 seconds. Before the onset of partial syncope, there are prodromal symptoms such as dizziness, tinnitus, sweating, blurred vision, pale complexion, and general malaise. This period is called the prodromal period. Symptoms such as fatigue, nausea, vomiting, lethargy, and even incontinence after the onset are called recovery periods. Therefore, the entire process of syncope may last for a few minutes or longer. Syncope usually does not produce retrograde forgetting, and the orientation and correct behavior often recover quickly.

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