Episodic syncope

Introduction Situational syncope is a manifestation of neuro-mediated syncope and one of the most common manifestations of syncope. The reason why it is called episodic syncope is that the syncope episode must have a certain situation. The appearance of this kind of situation constitutes the condition of syncope, and similar scenes can cause multiple episodes of syncope, which is a predisposing factor for syncope. Situational syncope is more common in the elderly. It refers to syncope that occurs under certain circumstances, including coughing syncope, urinary syncope, defecation syncope, and swallowing syncope.

Cause

1. Human brain weight accounts for 2% of body weight, brain blood supply accounts for 1/6 of cardiac output, brain oxygen consumption accounts for 20% of systemic oxygen consumption, and the critical value of cerebral blood flow required to maintain consciousness is per minute. 30ml/100g, syncope can occur when the cerebral blood flow drops below the critical value.

2. Changes in the chemical composition of the blood such as hypocapnia or hypoglycemia can also cause loss of consciousness. Blood glucose levels caused by any cause may be due to symptoms of autonomic nervous system activation and adrenaline release. When blood glucose levels are lowered to a low level, the brain's glucose uptake is reduced and the ability to use oxygen is decreased.

3. The occurrence of syncope during exercise or after exercise is related to exercise items, training level, physical condition, age and surrounding environment. In the process of weightlifting, the weight of the chest can reach 21.329.3kPa (160220mmHg), which hinders the filling of the left ventricle. Therefore, the blood output of the heart can be reduced, and the blood pressure can be reduced to 3.33~6.67kPa (2550mmHg). The blood flow is reduced and a transient syncope occurs. The practitioners who run short distances and long distances, as well as the walkers and bicycle practitioners, suddenly stop after intense training and competition. The blood is deposited on the skeletal muscles of the lower limbs, and the blood flow to the heart is suddenly reduced, causing gravity shock. This syncope often occurs. Among young practitioners or practitioners with poor training and no competition experience.

4, vascular decompression syncope, also known as simple syncope, can occur in normal people, the incidence of the first place in all types of syncope. There are factors such as emotional instability or strong mental stimulation before the attack, which causes the arterial pressure and the resistance of the whole body skeletal muscle to decrease, and the blood perfusion of the brain decreases to cause syncope. Young female athletes and newly recruited players participate in large-scale competitions. The tension before the game is easy to promote the disease. The recovery period of athletes, excessive fatigue and sudden participation in high-intensity training and competition after suspension of training are prone to this type of syncope.

5, the practitioner's orthostatic hypotension (post position), mostly occurs when the level suddenly changes to the upright position, due to sudden changes in body position, muscle pump and vascular regulation function disorders, resulting in a sudden drop in blood volume and Arterial blood pressure drops, and temporary cerebral ischemia occurs, which can occur in the standing position after completing the swimming competition.

6, paroxysmal muscle weakness, also known as sudden weakness. A decrease in the threshold of the central nervous system response caused temporary damage to the extremities of the extremities and collapsed. This syncope occurred in athletes in rowing competitions.

7. The sudden loss of primary consciousness often occurs after intense competition and high-intensity training. The reason is different from the gravity blood distribution and the syncope caused by reflex vasodilation. It is due to the hypoxia of the brain stem reticular tissue. Hypocapnia causes abnormalities in the direction of nerve conduction and fainting occurs. This syncope occurs during long distance races.

8. Loss of consciousness in diving and underwater swimming is the main cause of sudden death. Excessive ventilation before swimming and diving is to prepare for air-conditioning. Excessive ventilation causes excess air to enter the alveoli, which reduces PCO2 in the body and causes alkalosis. When the PO2 of arterial blood is reduced to a certain extent, the brain tissue cannot work, and consciousness loss occurs. Muscle relaxation, apnea (suffocation) and spontaneous breathing movement, can cause drowning death after inhaling a considerable amount of water. The process that may be experienced is: hypoxia, loss of consciousness, muscle relaxation, apnea, inhalation of water and sudden death.

9. After a long period of intense exercise, the blood sugar produced by the body's blood sugar consumption is more common in long-distance running, marathon, long-distance skiing, skating and road cycling. People with a history of organic or functional hypoglycemia are prone to hypoglycemia when exercising.

10, cardiogenic syncope can occur in sports such as football, basketball, cycling, tennis, ice hockey, marathon and jogging. Both young and middle-aged people occur, and it is more common in middle-aged and older people. Myocardial oxygenation increases during intense exercise, causing myocardial ischemia due to insufficient coronary blood supply. In addition, physical activity can stimulate the sensitivity of the arterial wall or increase the secretion of catecholamines, causing myocardial insufficiency in coronary artery spasm, especially after strenuous exercise, the myocardium is in a special vulnerable period, myocardial perfusion is unstable, and immediately take a bath or shower. Causes myocardial ischemia, cardiac output reduces the lack of blood supply to the cerebral cerebral palsy.

11. Exercise can induce arrhythmias in people without structural heart disease, such as transient syncope during paroxysmal tachycardia. People with aortic or subvalvular stenosis often experience syncope during exercise or physical labor. Congenital heart disease can cause syncope after exercise due to obvious arterial hypoxia.

12, the practitioner is fainting in the heat stroke. Long-distance training and competition in hot summers are prone to syncope, especially in summer without wind or high humidity. During exercise, the body produces more heat. At this time, it cannot be effective by evaporation, convection, conduction and radiation. Loss of excessive heat in the body and elevated body temperature. In addition, due to the reduced blood volume of a large number of sweating cycles, the blood supply to the brain is reduced and consciousness is lost. Heat fainting occurs in sports such as long-distance running, marathon, cross-country running, cycling and soccer. The athletes have low training level and excessive fatigue, which is prone to heatstroke and fainting.

an examination

Related inspection

Cerebrospinal fluid glucose and serum glucose ratio

First, the medical history question

Syncope often suddenly lose consciousness, fall, pale, cold limbs, no convulsions, tongue bite and urinary incontinence. You should ask about the condition before syncope, the presence or absence of aura, the degree of consciousness disturbance during syncope, and the length of duration and the time. Whether there are pale, slow pulse, urinary incontinence and limb twitching; fainting often has sorrow, fear, anxiety, fainting, seeing blood, trauma, severe pain, sultry, fatigue and other stimulating factors. Urination, defecation, cough, blood loss, dehydration can also be an inducement; should understand the position and head position at the time of onset, from vertical position to standing position, often occur in orthostatic hypotension, carotid sinus allergic syncope occurs in the head position When suddenly turning.

Second, physical examination found

Cardiac syncope often has valvular heart disease, heart rhythm disorder, myocardial ischemia and other reasons. Cardiac auscultation may have heart murmur and arrhythmia, etc.; syncope caused by insufficient blood supply to the neck and vertebral artery, often found that one side of the carotid artery beats weakened. Or disappear, audible abnormal vascular murmurs and syncope during head-turning and head-up tests; syncope caused by brain stem lesions often have signs of brain stems such as cross-sac, crossover or dissociative sensory disturbance;; no pulse and subclavian Arterial sclerotherapy, often have lower blood pressure in one side of the upper limb, audible and murmur in the neck and supraclavicular fossa; primary erect hypotension measured three positions (lying, sitting, standing) blood pressure difference 50mmHg.

Third, auxiliary inspection

Electrocardiogram and cardiac B-ultrasound are suitable for cardiogenic syncope. Head CT, cerebral angiography, cerebrospinal fluid examination, cervical X-ray film and carotid artery and vertebral artery B-ultrasound are suitable for brain-borne syncope. More normal EEG.

Differential diagnosis

Differential diagnosis of situational syncope:

1, coughing syncope: more common in elderly bronchitis target=_blank> chronic bronchitis, obstructive pulmonary disease patients, can also be found in children's pertussis or bronchial asthma medical education network collection. Its clinical feature is that syncope occurs after a severe and frequent cough, which can be quickly restored without discomfort. The mechanism of occurrence is the increase of chest pressure caused by cough, affecting the venous return and reducing the amount of blood returning to the heart. The blood output of the heart suddenly decreases, the blood pressure drops rapidly, and the cerebrovascular resistance increases due to the cough. The result is a sudden drop in cerebral blood flow. Insufficient, causing sudden syncope. The key to treatment is to control the primary disease, stop coughing, and use cough medicine reasonably when coughing occurs.

2, urinary syncope: more common in older men, with slow-arrhythmia patients with bradycardia and cerebral arteriosclerosis as the main target. The clinical feature is sudden loss of consciousness after rapid urination at night when he urinates. He falls to the ground and can quickly wake up after falling to the ground. Individuals may have head trauma or even intracranial hemorrhage due to head collision, which is life-threatening. The cause of syncope is caused by a sharp decrease in bladder pressure, which causes dilatation of the lower abdomen, reduces venous return, affects cardiac output, and exerts a forceful urination to make the heart expand and compress, further affecting cardiac output and inducing syncope. Therefore, the elderly should pay attention to not want to urinate during sleep, do not rush to stand up when urinating, do not urinate too much. Anyone with a history of urinary syncope may take a squat or sitting position during urination at night, and stand up slowly after urinating. If there is a bradycardia, the cause should be identified and a contraceptive treatment such as atropine should be given.

3, defecation syncope: more common in the elderly. Because the elderly are constipated, frequent defecation and excessive breath can affect the blood output of the heart. In addition, the intra-abdominal pressure drops after defecation, the blood in the abdominal cavity is stagnant, and the blood volume is reduced. If you stand quickly after defecation, it is easy to cause syncope. Therefore, the elderly should pay attention to the prevention and treatment of constipation, drink plenty of water on weekdays, eat fresh vegetables and fresh fruits such as bananas and citrus to increase the intake of plant fiber and prevent constipation. If you have experienced constipation or elderly people with habitual constipation, you should strengthen your diet. For example, drink a cup of light salt water every morning, drink 1 cup of honey sesame oil before going to bed, and eat sesame oil with spinach and fried leeks.

4, swallowing syncope: generally seen in patients with esophagus, throat, mediastinal disease or severe atrioventricular block, more common in the elderly. The patient may cause vagus nerve stimulation due to swallowing action or coughing, reflexively lowering the heart rate, and the cardiac output suddenly drops and causes syncope. It is characterized by no aura and has nothing to do with body position. Atropine can stop the attack. The key to this is to treat the primary disease before it can effectively control the syncope.

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