Neurological disorders due to open heart surgery

Introduction to neurological diseases caused by open heart surgery Open heart surgery with cardiopulmonary bypass, such as mitral or aortic valve replacement, congenital heart defect repair, ventricular aneurysm resection, coronary artery bypass grafting and heart transplantation, etc. The central nervous system, especially the possibility of brain damage, has been significantly reduced in recent years due to the continuous improvement of surgical techniques and artificial heart-lung machines, but it has not been completely avoided. basic knowledge The proportion of illness: 0.006% Susceptible people: no special people Mode of infection: non-infectious Complications: endocrine disorders

Causes of neurological diseases caused by open heart surgery

(1) Causes of the disease

The cause of neurological damage caused by open heart surgery is difficult to explain with a single factor. The main ones are as follows:

1. Inappropriate cerebral perfusion: including low perfusion pressure and longer perfusion time.

(1) Low perfusion pressure injury: Tufo et al considered that the mean arterial pressure during cardiopulmonary bypass, the level of decrease and the length of time are related to brain damage. In the patients he observed, the mean arterial pressure was 60 mmHg or more, brain damage The incidence rate is 27%, 45% at 50-59mmHg, 55% at 40-49mmHg, and 78% at 40mmHg or below, compared with 40mmHg and above 60mmHg for the two phases. The incidence of damage is three times that of the latter.

Some scholars (Gonzalez-Scarano et al., 1981) also considered that the average arterial pressure should be maintained above 50 mmHg when reviewing the nerve damage caused by a large series of coronary artery bypass grafts. Branthwaite (1973) pointed out that when the extracorporeal circulation started, arterial pressure Sudden decline, at this time, the cerebral perfusion is changed from pulsating to non-pulsating, which makes the brain automatically adjust to obstacles, and it is difficult to compensate, which affects brain function.

From the age factor, Tufo et al found that the age is lower than 40 years old, even if the average arterial pressure continues to decrease, the chance of brain damage can still remain low; if the average arterial pressure is below 40mmHg at 40 to 50 years old, then the brain The incidence of damage can be increased, he proposed that for elderly patients, the arterial pressure should be maintained at 60mmHg.

(2) Long perfusion time: In contrast, Sotaniemi (1980) considered that the mean arterial pressure of perfusion was less important for brain damage, and the perfusion time was a risk factor for brain damage, and it was considered that it was not related to age factor. According to Sotaniemi's statistics, in those patients with a perfusion time below 2 hours, 19.5% of patients had brain damage, while those above 2 hours had a rise to 51.9%, and there was a statistically significant difference.

Branthwaite (1972) found that 35.3% of patients had brain damage after perfusion for more than 180 minutes, 29.2% for 121-180 min, 15.1% for 90-120 min, and 21.0% for 61-90 min. Between 31 and 60 minutes, 8.1%, and those below 30 minutes were 7.4%. Therefore, it is considered that the perfusion time is long and the possibility of brain damage increases.

In other literatures, the perfusion time is more than 2 hours, the age is large, and the chance of brain damage is also increased. Statistics show that in patients under 50 years old, when the extracorporeal circulation time exceeds 2 hours, the brain damage is less than 2 hours. 2 to 3 times more, if the age is above 50, the average arterial pressure is below 50mmHg, the longer the perfusion time, the more brain damage occurs.

2. Microembolization: It has been reported that brain damage is caused by microembolism in the brain.

Fat embolism is mainly caused by sternotomy during surgery or by inhalation of the perfusion system due to the fat globules in the mediastinum entering the pericardial cavity.

3. Preoperative neurological diseases: Sotaniemi found that the brain has a cerebrovascular accident or syncope before surgery. The author has a brain damage after surgery, and the author with transient cerebral ischemia before surgery is not easy to cause brain damage. In one group of patients, there were 9 cases of cerebrovascular accident and syncope before surgery, and 6 cases of brain damage occurred after operation; 5 cases had transient ischemic attack before surgery, only 2 cases occurred after operation. Brain damage, in addition, 3 cases of epilepsy before surgery, 2 cases of brain damage after surgery, preoperative neurological disorders including cerebral embolism, atherosclerosis, epilepsy, congenital basal ganglia lesions, acute ischemic spinal cord damage and past Hemiplegia occurred after bypass surgery, but Tufo et al. believe that the occurrence of brain damage has nothing to do with preoperative neurological disease.

4. Age: Javid et al (1969) pointed out that with the increase of age, the number of brain damage also increased. According to Branthwaite's statistics, 38.5% of the patients aged 61-70 had brain damage, and those aged 51-60 years old were 32.6%, 41-50. The age of the elderly was 19.2%, and the incidence of those under 40 was lower. In contrast, according to Sotaniemi's statistics, the occurrence of brain damage was not related to age.

5. A large number of blood loss during operation: A large number of blood loss during operation is related to brain damage, and the amount of blood loss is related to the length of operation. In Sotaniemi, 10 cases have blood loss of more than 2500ml during operation, and 9 cases have occurred after operation. Brain damage.

6. Unpredictable accidents during surgery and other: Brain damage can occur if the oxygenation of the oxygenator fails during the operation, and the arrhythmia or severe dilute anemia after coronary artery bypass graft can promote the neurological disorder. Occurred, as to whether the degree of calcification of the aortic valve and mitral valve is related, it is not certain.

(two) pathogenesis

In patients with intracranial hemorrhage caused by open heart surgery, Humphreys et al (1975) believe that there is a hypertonic solution in the pre-filled fluid of the heart-lung machine, causing the brain to shrink and causing the traffic vein (bridge vein) to be involved in the rupture. In addition, bleeding should also be considered and the position of the head at the time of surgery, the application of anticoagulant heparin, elevation of the superior vena cava or right atrium, hypothermia or changes in arterial blood gas analysis.

Regarding neurological damage caused by heart transplantation, Sila (1989) has analyzed that in the autopsy group of cerebrovascular accidents, 50% of patients found hypoxic-ischemic neuronal damage, stratified necrosis and old or recent infarction. It is believed that the changes of ischemia and hypoxia are related to the mean arterial pressure of the heart-lung machine being less than 50 mmHg and postoperative hypoperfusion and circulatory failure. The newly-infarcted patients, accounting for 13% of the autopsy patients, and the cardiac embolism caused by acute cardiac rejection, Intraoperative aortic arch thrombosis, fat embolism and cerebral vascular atherosclerosis are associated with intracerebral hemorrhage. If it occurs, the mechanism may be that when the brain is automatically dysfunctional, blood pressure and cerebral blood flow suddenly increase. Related to cerebral perfusion, for postoperative encephalopathy and mental behavior disorder, may be related to hypoxic-ischemic brain damage, in addition, and a variety of metabolic disorders such as liver, renal dysfunction is also associated with convulsions in patients with postoperative brain In addition to higher perfusion pressure, severe metabolic disorders are associated with hypomagnesemia, and because of the need for immunosuppressive agents to control rejection reactions, The opportunistic infection of CNS causes a variety of fungal, viral, toxoplasmosis and bacterial infections, but the high incidence of infection is not within the first month after surgery, but within half a year after surgery.

Major pathological changes: A large series of reports were analyzed by Aguilar et al (1971) 214 autopsy data, 31 cases (15%) were normal brain, and other brains had lesions, mainly:

1 small blood vessel embolization;

2 acute intracerebral punctate, perivascular or focal subarachnoid hemorrhage;

3 acute extensive ischemic neuronal damage (called triad), small blood vessel emboli can be composed of fat, cellulose platelets or lens substances, bleeding is widely scattered and fresh, mostly in the brain And subarachnoid space, the cause of bleeding is caused by ischemia, hypoxia and metabolic disorders, acute neuronal degeneration is common in the Sommer segment of the hippocampus, the occipital cortex, the pallidum, Occasionally in the narrow band of the cerebral cortex and central gray matter, the death of neurons in the lesion area is widespread, reflecting the consequences of ischemia and hypoxia. In addition, if brain softening is found, it is mainly caused by large blood vessel surgery.

Witoszka et al (1973) in 20 autopsy materials, see 16 cases with pathological changes, the most common is hypoxic neuronal damage (13 cases), which is often located in the hippocampus, brain and cerebellar cortex, followed by cerebral infarction (8 For example, clinically mostly focal dyskinesia, severe diffuse cortical necrosis (6 cases), embolism caused by calcareous granules (3 cases) and cerebellar tonsil (2 cases), analysis of causes of death, 9 cases It is due to brain damage, and the rest are extra-brain factors such as myocardial infarction, persistent bleeding, shock or arterial embolism.

Tufo et al (1980) autopsy 10 cases, 9 cases of internal brain damage, mainly found small, multiple diffuse whole white matter and gray matter hypoxia changes, especially in the hippocampus, local tissue in the acute phase can be seen empty Tissue vacuolation and neuronal death (7 cases), in addition, there are embolic lesions in the gray matter.

Unlike the above, Humphreys et al (1975) reported 16 cases of intracranial hemorrhage after surgery, 12 of which were found at autopsy, and 4 were confirmed by surgery. 11 cases of subdural hematoma in different parts, the amount of bleeding was 15 ~60ml; 1 case of epidural hematoma, the amount of bleeding is 175ml; the other 4 cases of intracerebral hematoma, the amount of bleeding is 15 ~ 60ml (1 case in the subarachnoid space less than 15ml blood).

Montero et al (1986) analyzed the neuropathology (brain and spinal cord) of 23 patients who died of heart transplantation. Only 4 patients (17%) had no abnormalities, most of them were vascular lesions (60%), followed by infection (20%). ) vascular damage in the brain includes thrombosis, embolism, old or recent infarction, and recent bleeding, and some secondary to circulatory failure (the latter including postoperative hypotension, decreased cardiac output, or increased peripheral vascular resistance). CNS infection mainly originates from the application of immunosuppressive agents. The pathogens found are cytomegalovirus, Aspergillus, Candida, Toxoplasma gondii, etc. The majority of the primary lesions in the lung are in the lungs, followed by the heart, in previous reports. Among them, tumors have been found and have the largest lymphoma (Penn, 1982).

Prevention of neurological diseases caused by open heart surgery

For neurological damage after open heart surgery, it is important to pay attention to preoperative, intraoperative prevention of possible damage, and to minimize concurrent nervous system dysfunction.

Neurological complications caused by open heart surgery Complications, endocrine disorders

The clinical manifestations are diverse, heart disease symptoms and neurological symptoms coexist, and can affect the patient's digestive and endocrine functions.

Neurological symptoms caused by open heart surgery Common symptoms Sensory disturbance Ataxia illusion Peripheral nerve damage Pupil abnormality Eyeball tremor Visual dysfunction Coma Heart failure hemianopia

1. Damage to the nervous system can affect all levels, but the most common brain damage (79%), followed by the cerebellum, brain stem and spinal cord, peripheral nerve damage, such as brachial plexus or ulnar nerve damage should be considered during surgery, The nerve is caused by pulling or compression, and the damage of the central nervous system can be diffuse or focal. In severe cases, the coma occurs during the operation, and the neurological symptoms appear until the death; the mild symptoms persist. It disappears in a few days, but it can also have long-term sequelae. Common symptoms include coma, confusion, paralysis, mental retardation, aphasia, varying degrees of hemiplegia, quadriplegia, central facial paralysis, sensory disturbance, visual impairment, quadrant hemianopia. Positive pathological reflexes are rare. The pupils are unequal, nystagmus, diplopia, trigeminal neuropathy and sucking reflex. Sometimes the symptoms appear after surgery for a few days, such as 2 to 3 days after coronary artery bypass grafting.

Sotaniemi reported that 37 cases of brain damage caused by heart valve replacement in 37 cases, including 24 cases of hemiplegia, 22 cases of cerebral hemisphere damage, 2 cases of spinal cord damage, 16 cases of right hemisphere damage, left hemisphere In 6 cases of damage, this right hemisphere is vulnerable to damage as mentioned in Javid et al. (1969). Sotaniemi believes that during the extracorporeal circulation, the thresholds of symptoms appearing after damage to the two hemispheres are different. Related, some authors have noticed that open heart surgery with cardiopulmonary surgery can cause intracranial hemorrhage, and typical intracranial hematoma (subdural, subdural and epidural) occurs within a few hours to several days after surgery. The clinical manifestations of space occupying in the brain, such as gradual coma, convulsions, large pupils on one side, and contralateral hemiplegia, are signs of cerebral palsy.

2. The nervous system damage caused by heart transplantation, the clinical manifestations of different weights are roughly divided into three categories:

(1) cerebrovascular: may be due to brain thrombosis, embolism, ischemia and hypoxia, intracerebral hemorrhage, rejection, heart failure, renal failure, sepsis, etc. headache, mental behavior abnormalities, transient aphasia, convulsions And varying degrees of hemiplegia and even coma.

(2) Central nervous system infections: Meningococcal diseases caused by opportunistic brain infections such as Aspergillus, Candida, Cryptococcus, Toxoplasma, Cytomegalovirus, Herpesvirus, and bacterial infections.

(3) Damage caused by immunosuppressive agents: long-term use of corticosteroids for emotional euphoria, agitation, steroid myopathy, etc. Since the use of cyclosporine, the dose of hormones has generally been reduced, making the above symptoms Also reduced, but in addition to toxic effects on the kidney and liver, cyclosporine also has a certain neurotoxic effect, can cause paresthesia, visual hallucinations, limb tremor, convulsions, leukoencephalopathy, cerebellar ataxia, myelopathy , sphincter disorders and axonal and demyelinating peripheral neuropathy, in addition, a small number of patients with long-term use of immunosuppressive agents due to long-lasting rejection caused tumors, especially lymphoma.

These three types of damage can vary in the same patient, so it should be carefully observed to understand the exact cause of the symptoms.

Examination of neurological diseases caused by open heart surgery

Arterial blood gas analysis, pulse, blood pressure, cerebral blood perfusion tomography, electroencephalography.

Diagnosis and diagnosis of neurological diseases caused by open heart surgery

diagnosis

According to the symptoms of the nervous system occurring during or after the operation of open heart surgery, it is not difficult to diagnose the complications caused by surgery, but it is often difficult to analyze the cause of damage to the nervous system, which is caused by damage. The factors are mostly comprehensive.

Differential diagnosis

1. Focal signs such as hemiplegia, aphasia, paraplegia and quadriplegia are generally vascular, and most of them are ischemic lesions, if the symptoms of diffuse brain damage such as coma, mental disorders, cognition and Psychological disorders and convulsions are often caused by ischemia and hypoxia in the brain.

2. If a heart transplant is performed and a long-term or high-dose immunosuppressive agent is used, hyperthermia and various brain symptoms may occur. In addition to consideration of persistent rejection, attention should be paid to whether an opportunity has occurred. Sexual brain infections such as fungal, viral or bacterial meningoencephalitis.

The above causes can be diagnosed by imaging methods such as CT and MRI of the brain and spinal cord and CSF for lumbar puncture. The examination of infectious pathogens can be detected by CSF and serum by PCR technique or by indirect fluorescent immunoassay. Antibodies to help identify the cause.

3. For peripheral nerve damage, it is often caused by mechanical compression for a long time during the operation.

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