Exertional syncope suggests cardiac outflow tract obstruction, mainly due to aortic stenosis. This syncope reflects cerebral ischemia caused by the simultaneous dilatation of peripheral vessels due to the inability to increase cardiac output during exertion. Hypovolemia and positive inotropic drugs (e.g., digitalis) can exacerbate outflow tract obstruction in patients with hypertrophic obstructive cardiomyopathy, and syncope may occur suddenly. Syncope often occurs immediately after exercise and is caused by decreased venous return, reduced left atrial pressure, and reduced ventricular filling.
Which symptoms are easily confused with exertional syncope?
I. Reflex syncope
1, simple syncope: also known as vasovagal syncope, vascular decompression syncope. It is more common clinically, and there are more obvious triggers before syncope, such as pain, high temperature, nervousness, fear, emotional excitement, poor ventilation, foul air, fatigue, continuous standing, hunger, pregnancy, and the later stages of various chronic diseases. The pre-syncope period lasts for a short period of time, usually 15-30s. If you lie down quickly and immediately during this period, the prodromal symptoms disappear, and the prodromal symptoms are mostly dizziness, nausea, pallor, and sweating. The performance of the syncope period is also temporary, lasting generally 30s to 2-3min, manifested as loss of consciousness, pale face, weakness of limbs, decreased blood pressure, slowed and weak heart rate, dilated pupils, loss of response to light, and attention should be paid to the presence of urinary incontinence, twitching of limbs, biting of the tongue, etc. Late symptoms of syncope may include transient weakness or dizziness, etc. Recovery is usually quicker and there are no obvious sequelae symptoms. Attention should be paid to the differentiation from epilepsy, hysteria and vertigo. In epileptic seizures, there are no obvious prodromal symptoms, loss of consciousness during seizures, incontinence, limb convulsions, biting of the tongue, etc. There are abnormal findings in EEG and brain CT or MRI. Hysteria attack mostly has obvious mental stimulation factors, the attack lasts long, there is no loss of consciousness during the attack, and there is reaction to the surrounding people and objects. Vertigo is a kind of motion hallucination or motion illusion. Patients feel that the external environment or themselves are rotating, moving or shaking, which is caused by the lesion of vestibular nervous system.
2, upright low pressure syncope: When the patient changes from the prone position to the upright position, the blood pressure drops rapidly and causes insufficient cerebral blood flow, and when syncope symptoms appear, it is called upright hypotension.
3, urinary syncope: urinary syncope occurs when urination, or at the end of urination, causing a reflexive drop in blood pressure and syncope. It occurs most often when the patient wakes up at midnight to urinate, and can also occur in the early morning or when the patient gets up from a nap to urinate.
4, carotid sinus syncope: also known as carotid sinus syndrome, occurs when the carotid artery is irritated, carotid artery sclerosis or its adjacent lesions, or when the collar is too tight. If there is a tumor near the carotid sinus, inflammation, trauma, strain or compression of the carotid sinus by external force, etc. leads to carotid sinus syncope attack. Clinically, it can be divided into.
(1) Vagal type: with reflex sinus bradycardia, or with atrioventricular block.
(2) Decompensated type: the main manifestation is a significant decrease in blood pressure.
(3) Central type: the main manifestation is syncope, while blood pressure and heart rate are not obvious. In clinical practice, carotid sinus pressurization experiments can slow down the heart rate or lower the blood pressure or cause syncopal episodes.
5, supine hypotensive syncope: mainly seen in late pregnancy, huge intra-abdominal tumors, thrombophlebitis, diaphragm-like obstruction in the inferior vena cava and primary smooth muscle tumors in the veins. The main manifestations are: sudden drop in blood pressure, increased heart rate and syncopal episodes when the patient is supine. The mechanism of occurrence is mainly due to mechanical compression of the inferior vena cava by the mass, resulting in a sudden decrease in the return blood to the heart.
II. Cardiogenic syncope
Cardiogenic syncope is mainly due to cardiac arrest, severe arrhythmia, myocardial ischemia, etc., resulting in a sudden drop in cardiac blood output and insufficient cerebral blood supply, leading to syncopal episodes. The onset of syncope in the upright position, without obvious aura manifestations, mostly suggests cardiogenic syncope or upright hypotensive syncope. If the onset of syncope in the supine position can mostly suggest cardiogenic syncope.
Third, cerebral syncope
1, syncope caused by insufficient local blood supply to the brain: hypertension, pregnancy hypertension and glomerulonephritis, etc., may cause a sudden rise in blood pressure, sudden headache, vomiting, and even syncopal episodes, generalized convulsions, neurological localization signs and high cranial pressure syndrome, etc. Cerebrogenic syncope causes syncope for a longer period of time. Patients with cerebrovascular stenosis may also suffer from localized cerebral blood supply deficiency, which may lead to syncope. When syncope occurs, there is a possibility of cerebral thrombosis due to the drop in blood pressure and slow blood flow.
2, syncope caused by lesions in the brain tissue itself: mainly affects the vasomotor center of the brainstem, the attack can be longer and the prognosis is not good. Mainly seen in: brainstem tumors, class disorders, degeneration, nai high spinal cord lesions, etc.
3, other: certain drugs such as sedatives, tranquilizers, anesthetics, etc. can inhibit the central neurovascular motor center leading to syncopal episodes.
Fourth, other
As the causes of syncope are more, according to different triggers called different syncope, such as swallowing syncope, various cerebrovascular diseases caused by local blood supply deficiency in the brain syncope, lesions of the nerve tissue itself, intracranial injury causing syncope, and such as hyperventilation syncope, hypoglycemic syncope, severe anemia syncope, crying most syncope, etc.
Syncope is a group of clinical manifestations of sudden, transient loss of consciousness and loss of body control caused by various reasons, which both recover on their own. Typical syncopal episodes are brief, with loss of consciousness rarely lasting more than 20-30 seconds. Some syncopal episodes are preceded by prodromal symptoms such as dizziness, tinnitus, sweating, blurred vision, pallor, and general malaise, and this period is called the prodromal phase. After the attack, symptoms such as fatigue and weakness, nausea, vomiting, drowsiness, and even urinary and fecal incontinence occur, which is called the recovery period. Therefore, the entire course of syncope may last for several minutes or longer. Syncope usually does not produce retrograde amnesia, and disorientation and correct behavior often return rapidly.
Labor syncope often occurs immediately after exercise, and prolonged syncope can cause seizures.