Sudden death coronary heart disease
Introduction
Introduction to sudden death coronary heart disease Sudden-type coronary heart disease refers to a person who has no history of heart disease or only mild heart disease. The condition is basically stable. There is no obvious external cause, non-trauma or self-injury. The heart loses effective contraction due to heart failure or mechanical failure. death. basic knowledge Sickness ratio: 2% Susceptible people: no specific people Mode of infection: non-infectious Complications: hypotension, coma, adult respiratory distress syndrome, atelectasis
Cause
Cause of sudden death coronary heart disease
(1) Causes of the disease
1. Etiology According to foreign data, 81% of patients with severe coronary heart disease have obvious coronary heart disease. The main pathological feature is more than one coronary artery >75% stenosis, at least one of which has >75% stenosis and 94%. 58% of patients with acute coronary occlusion, 44% had healed myocardial infarction, and 27% had acute myocardial infarction. These studies suggest that extensive coronary artery disease is the main pathology of sudden death of coronary heart disease, but intracoronary Thrombosis and coronary vasospasm further promote the decline of myocardial damage and thus induce ventricular fibrillation and cardiac arrest.
2. Common causes
(1) Physical exertion: Excessive fatigue and long-lasting labor.
(2) Full meal, drinking and excessive smoking.
(3) Excessive stimulation and excitement of the mental nerves.
(4) severe cardiac insufficiency: unstable angina.
(5) low potassium, hypomagnesemia.
(6) Certain antiarrhythmic drugs.
(two) pathogenesis
Research suggests that extensive coronary artery disease is the main pathology of sudden death of coronary heart disease, and thrombosis in the coronary arteries and coronary vasospasm further promote the decline of myocardial damage and thus induce ventricular fibrillation and cardiac arrest. The mechanism may be:
1. Due to local myocardial hypoxia, the normal conduction pathway is inhibited, and the pacing activity of myocardial conduction fibers is enhanced, resulting in ectopic beats and reentry agonism.
2. Imbalance of electrolyte ions, especially hypokalemia or hypotension caused by diuretics and myocardial ischemia and necrosis lead to potassium outflow in tissues, which reduces the transmembrane resting potential of some cardiomyocytes and improves self-discipline.
3. Patients with neurological dysfunction are often accompanied by sympathetic or parasympathetic over-excitability.
Prevention
Sudden death coronary heart disease prevention
1. Primary prevention of coronary heart disease in high-risk populations. There is still no accurate and specific short-term predictor of sudden death in coronary heart disease. Some patients with coronary heart disease have no coronary heart disease before sudden death, and epidemiological prospective studies have shown that Risk factors for coronary heart disease, such as hypertension, hypercholesterolemia and smoking, are consistent with the trend of coronary heart disease and sudden onset of coronary heart disease. At present, primary prevention of coronary heart disease in the population of coronary heart disease risk factors That is, to control the risk factors of coronary heart disease to reduce the incidence of coronary heart disease, which is the most fundamental measure to prevent sudden death of coronary heart disease.
2. Strengthen the first-aid knowledge education on the scene of sudden death, and establish a perfect first-aid system. At present, patients with cardiac arrest in the hospital in China have a large improvement in the success rate of recovery, but it is still not ideal, especially in the pre-hospital recovery success rate. Low, efforts must be made to improve the success rate of recovery, and strive to find a way to effectively improve the blood supply of important organs, promote spontaneous circulation recovery and improve functional recovery of the nervous system in patients with cardiac arrest in and out of the hospital.
Complication
Sudden death coronary heart disease complications Complications hypotension coma adult respiratory distress syndrome atelectasis
Due to hypoxia caused by cardiac arrest, carbon dioxide retention and acidosis, electrolyte imbalance has not been corrected, the function of the vital organs of the body has not recovered after injury, and cardiovascular function and blood flow are often found after spontaneous circulation recovery. Disorders such as learning, often have shock, arrhythmia, cerebral edema, renal insufficiency and secondary infections and other complications.
1. Hypotension and shock
Hypoxia and carbon dioxide accumulation can affect myocardial function, intrathoracic heart compression or intracardiac puncture injection of too many times, all affect the function of the myocardium, so that the stroke volume is reduced, resulting in hypotension, cardiac pump function changes in patients with cardiopulmonary resuscitation In the early stage of resuscitation, the cardiac output was mostly low. Because the heart rate increased, the cardiac output was still compensated. However, the left ventricular stroke index and peripheral vascular resistance increased, the myocardial contractile function decreased significantly, and the cardiac index decreased.
2. Heart failure
The heart relapses for too long, the myocardium is in a state of ischemia and hypoxia for a long time, causing damage to the heart; the application of a large number of vasoconstrictor drugs in the rescue, increasing the peripheral vascular resistance, correspondingly increasing the burden on the heart, coupled with arrhythmia, fluid input Excessive, too fast and electrolyte imbalance and acid-base balance disorders can damage the myocardium, increasing the burden on the heart and easily causing acute left heart failure.
3. Arrhythmia
The causes of arrhythmia mainly include myocardial hypoxia damage after cardiac arrest, severe electrolyte or acid-base balance disorder, the effect of resuscitation drugs, some drugs are misplaced into the myocardium during intraventricular injection, excessive hypothermia, etc. due to the above pathology Physiological and biochemical changes directly affect the myocardium, causing increased stress in the myocardium and causing various arrhythmias.
4. Respiratory insufficiency
During the rescue of cardiopulmonary resuscitation, the patient is in a coma, the cough reflex disappears, the airway secretions cannot be cleared in time, the atelectasis is easily caused, the ventilation/blood flow ratio is imbalanced, and the intrapulmonary shunt increases, leading to hypoxemia; Inhalation of fluids and reflux of gastric contents, as well as dehydration, hibernation drugs, low-temperature and high-dose corticosteroids, can cause lung infections; therefore, adult respiratory distress syndrome can occur in the early stages of resuscitation.
5. Nervous system complications
Patients with cardiac arrest are successful in initial resuscitation, but the neurological morbidity rate is extremely high, ranging from focal to diffuse brain damage, from temporary to permanent damage, from mild dysfunction to irreversible Sexual coma and death, therefore, brain resuscitation not only to quickly improve and correct the immediate impact of cerebral ischemia, but also actively prevent secondary cerebral ischemia and hypoxia damage after sudden arrest, so that brain function can be restored as soon as possible.
6. Renal failure causes renal blood flow to stop or decrease due to cardiac arrest and hypotension, causing renal cortical ischemia and renal vasoconstriction. When blood pressure is lower than 8.0 kPa (60 mmHg), glomerular filtration stops, and Increases angiotensin and renin activity, further causing renal vasoconstriction and renal ischemia, which lasts for too long and can cause renal failure.
7. Water and electrolyte balance imbalance
In the process of rescuing patients with cardiac arrest, water and electrolyte disorders are prone to occur, such as hyperkalemia, hypokalemia, high sodium and hyponatremia.
8. Acid-base metabolism imbalance
During cardiac arrest and resuscitation, tissue acidosis and the resulting acidemia are dynamic processes due to hypoventilation and hypoxia metabolism, depending on the length of cardiac arrest and blood during CPR. Flow level.
9. Infection
The cause of secondary infection after resuscitation is not only related to the invasion of pathogenic bacteria, but more importantly, in the process of resuscitation, due to the weakening of the body's defense ability, the pathogens take advantage of it, especially some non-pathogenic bacteria that are not valued in the human body or the environment. Or weak bacteria have become an important pathogen of infection, such as pneumonia, sepsis, urinary tract infections and other infections.
10. Digestive system complications
After successful resuscitation in patients with cardiac arrest, the microvascular hypoxic zone persists, and the hypoxic zone stimulates and enhances the immune response, thereby increasing oxygen demand and oxygen uptake, causing hypoxemia to worsen, due to the fragility of the intestinal mucosa. Hypoxic tolerance is extremely poor, prone to low perfusion injury, intestinal failure and upper gastrointestinal bleeding.
11. Other complications
(1) Hyperglycemia: The body will have an increased blood glucose response after suffering severe traumatic stress.
(2) hyperamylasemia: may be related to pancreatic ischemia after cardiac arrest, hypoxia leads to a large release of pancreatic amylase.
Symptom
Symptoms of sudden death coronary heart disease common symptoms chest pain ventricular fibrillation elderly calf edema arrhythmia loss of consciousness convulsions dyspnea convulsions fatigue blood viscosity increased
According to foreign literature reports, only 12% of sudden cardiac deaths have been diagnosed with heart disease within 6 months before death, while the vast majority of patients are neglected due to lack of specificity of symptoms.
Chest pain, difficulty breathing
The deceased person felt angina pectoris or angina pectoris with altered nature in the days or weeks before the onset of illness, and had a higher chance of finding coronary thrombosis at autopsy.
2. Weak, weak
In many studies, fatigue is found several days or weeks before sudden cardiac death, and weakness is a particularly common symptom.
3. Specific heart symptoms
Persistent angina, arrhythmia, heart failure, etc., foreign literature reports that 24% of sudden cardiac death patients have specific cardiac symptoms 3.8h before cardiac arrest, but most studies believe that these symptoms are rare, especially those who die instantly By.
4. Sudden death of coronary heart disease is sudden, mostly in the winter, half of the life without any symptoms, the vast majority occurred outside the hospital, if the patient can be rescued in time may survive.
5. Performance of cardiac arrest
1 sudden loss of consciousness or convulsions, accompanied by convulsions;
2 large arteries (carotid artery, femoral artery) beat disappeared;
3 auscultation heart sound disappears;
4 sigh-like breathing or breathing stop with sputum;
5 pupils are scattered, mucous membranes are cyanotic,
6 The wound is no longer bleeding during surgery.
Examine
Examination of sudden death coronary heart disease
Metabolic acidosis due to hypoxia, decreased blood pH, and increased blood glucose and amylase may occur.
Electrocardiogram examination
There are 3 kinds of graphics:
(1) Ventricular fibrillation (or flutter): showing ventricular fibrillation or fluttering waves, accounting for about 80%, and the success rate of resuscitation is the highest.
(2) ventricular arrest: the electrocardiogram is a straight line or only atrial wave.
(3) ECG-mechanical separation: Although the ECG has a slow and wide QRS wave, it does not produce effective mechanical contraction of the heart. It is generally believed that the success rate of ventricular pause and electromechanical separation is lower.
2. EEG
Brain waves are low.
Diagnosis
Diagnosis and diagnosis of sudden death coronary heart disease
Diagnostic criteria
With reference to relevant standards at home and abroad, any one of the following conditions can be diagnosed as sudden death of coronary heart disease:
1 In the past, he was diagnosed with coronary heart disease or suspected coronary heart disease, sudden onset of angina and died within 6 hours or during sleep.
2 Sudden angina or cardiogenic shock, ECG showed acute myocardial infarction or aura of infarction, died within 6h.
3 After the death, it was confirmed by autopsy that there was obvious coronary arteriosclerosis.
Because the direct cause of sudden death of coronary heart disease is caused by ventricular fibrillation, and the electrophysiological basis of ventricular fibrillation is ventricular myoelectric instability, the prevention of sudden death of coronary heart disease is mainly to predict the occurrence of ventricular fibrillation. The following are highly dangerous. :
1. A patient with a history of coronary heart disease who has had ventricular fibrillation.
2. Unstable angina pectoris frequent with ST segment depression > 2mm.
3. Organic heart disease ventricular enlargement, cardiac dysfunction accompanied by syncope.
4. Organic heart disease with low potassium, low magnesium.
5. Changes in environmental factors such as excessive alcohol and tobacco, overwork, emotional agitation, sudden stress, etc.
These conditions can aggravate myocardial ischemia, increase the release of catecholamines, and reduce the threshold of ventricular fibrillation to induce sudden death. For such patients, active preventive and therapeutic measures should be taken. For those who have the following results, they should also be considered as highly dangerous. Timely treatment should be given.
6. ECG prompts frequent multi-source ventricular premature contraction, and has the following characteristics:
The 1-ventricular premature contraction QRS amplitude <1.0mV.
The 2-ventricular premature contraction QRS complex time was >0.16s.
3 ventricular premature contraction QRS, T wave and QRS main wave direction, and T wave high point symmetry.
4 parallel rhythm type ventricular premature contraction; 5 height atrioventricular block, high indoor conduction block.
7. Ventricular late potential (VLP) positive can be used as a screening index for a malignant arrhythmia.
8. Heart rate variability (HRV) analysis abnormalities can evaluate the function of the cardiac autonomic nervous system. Normal human heart is affected by sympathetic and vagus nerves. The electrical stability of the myocardium depends on the balance between the two. Patients with acute myocardial infarction due to myocardial necrosis The sympathetic and vagus nerves that innervate the heart are damaged, especially the vagus nerve damage is more serious, and the sympathetic nerve activity is relatively enhanced, resulting in an increase in ECG instability and a decrease in the threshold of ventricular fibrillation, which is prone to ventricular fibrillation and sudden death.
90% of sudden cardiac death is caused by coronary heart disease, but the understanding of the law of sudden death from coronary heart disease is not sufficient.
During cardiac arrest, wheezing or cessation of breathing often occurs, but sometimes the breathing is still normal. During the cardiac arrest, if the resuscitation is rapid and effective, the automatic breathing can always be good. When the cardiac arrest occurs, the skin often appears. The mucous membranes are pale and cyanotic, but they are easily overlooked under the light. If there is severe suffocation or hypoxia before cardiac arrest, the cyanosis is often obvious.
Cardiac arrest can cause sudden loss of consciousness and should be differentiated from many diseases such as fainting, epilepsy, cerebrovascular disease, major bleeding, pulmonary embolism, etc., which can sometimes cause cardiac arrest, such as the disappearance of the aorta of these patients. Resuscitation should be performed immediately, and heart compression is not a problem for the beating heart, but it can also help the heart with insufficient cardiac output.
