Sudden cardiac death



Sudden cardiac death (SCD) refers to sudden death due to various cardiac causes. Can occur in patients with or without heart disease, often without any life-threatening pre-existing performance, sudden loss of consciousness, death within 1 hour after the onset of acute symptoms, is a non-traumatic natural death, characterized by unexpectedly rapid death . More than 91% of SCD is caused by arrhythmia, and some non-EC accidents such as heart rupture and pulmonary embolism can also die rapidly within 1 hour, but its mechanism and prevention are different from arrhythmia sudden death. . With the clinical application of the implantable cardioverter defibrillator (ICD), the understanding of SCD through its monitoring system is further deepened.



About 75% of cardiac deaths are coronary atherosclerotic heart disease, especially acute myocardial infarction (acute myocardial infarction). Others include valvular heart disease, hypertrophic and dilated cardiomyopathy, cardiac conduction abnormalities (QT interval prolongation syndrome, cardiac arrest) and severe ventricular arrhythmias. In addition, digital poisoning such as digitalis and quinidine may also be caused.


an examination

Related inspection

Dynamic electrocardiogram (Holter monitoring) M-mode echocardiography (ME) Doppler echocardiography angiography

The patient suddenly loses consciousness and may be accompanied by generalized convulsions; the aorta beat disappears and the heart disappears; the breath is asthmatic or even stopped; the pupil is dilated.

1. Patients with a history of coronary heart disease and 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.

In these cases, myocardial ischemia is aggravated, catecholamine release is increased, and the threshold of ventricular fibrillation is lowered 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 and should be treated promptly.

6. ECG Tip: Frequent multi-source ventricular premature contraction, and has the following characteristics: 1 ventricular premature contraction QRS amplitude <1.0mV; 2 ventricular pre-contraction QRS wave group time>0.16s; 3 room Pre-sex contraction QRS, T wave and QRS main wave direction are the same, 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 indicator for a malignant arrhythmia.


Differential diagnosis

Sudden death: refers to a person who seems to be healthy in normal times, and sudden death due to sudden onset or deterioration of a potential natural disease. It has three characteristics, one sudden death, two deaths unexpected, and three natural deaths or non-violent deaths.

Sudden sleep: J wave syndrome is the culprit of sleep stagnation, and J wave has an intrinsic connection with sudden death. Detailed medical history and family history are the key to diagnosis. Unexplained syncope, syncope, a history of sudden death, and a history of familial cardiac death are important clues to diagnosis. Brugada syndrome can be diagnosed if the patient has a typical type I ECG change and one of the following clinical manifestations, and excludes other factors that cause ECG abnormalities: 1 ventricular fibrillation is recorded; 2 self-terminating polymorphic ventricular tachycardia; Family heart death history.

Sudden left heart failure: Acute left heart failure refers to a sudden decrease in left ventricular discharge due to various reasons, resulting in severe left ventricular and left atrial diastolic blood pressure, acute pulmonary blood stasis.

Sudden right heart failure: Acute right heart failure refers to the clinical situation caused by a sharp decrease in right ventricular myocardial contractility due to a sharp decrease in right ventricular myocardial contractility or a sudden increase in right and left anterior and posterior loads. Syndrome. Acute right heart failure is more common in acute massive pulmonary infarction and acute right ventricular infarction.

Cardiac arrest: refers to the fact that the myocardium still has bioelectrical activity, but no effective mechanical function, intermittently appearing a slow but very weak and incomplete "shrinkage" condition, and there are intermittently wide, deformed, low amplitude QRS on the electrocardiogram. Wave group, the frequency is more than 20 to 30 times per minute. At this time, the myocardium has no contraction and blood discharge function, and the heart sound is not heard when the heart is auscultated, and the peripheral arteries are not beaten.

Cardiac decompensation: When heart disease becomes worse and heart function declines beyond its compensatory function, cardiac decompensation occurs.

Myocardial infarction: refers to the interruption of coronary blood flow on the basis of coronary artery disease, causing severe and long-lasting acute ischemia in the corresponding myocardium, eventually leading to myocardial ischemic necrosis. Systemic symptoms: fever, increased white blood cells, increased erythrocyte sedimentation rate; gastrointestinal symptoms: more common in patients with inferior wall infarction; arrhythmia: seen in 75% to 95% of patients, occurring within 1 to 2 weeks of onset, and 24 hours More common inside, anterior wall myocardial infarction is prone to ventricular arrhythmia, inferior myocardial infarction prone to atrioventricular block.

Heart failure: mainly acute left heart failure, occurring in the first few hours of onset, the incidence rate is 32% to 48%, manifested as dyspnea, cough, cyanosis, irritability and other symptoms.

Pulmonary heart failure: Pulmonary heart disease, referred to as pulmonary heart disease, is a pulmonary hypertension secondary to various chest and bronchial lesions, which ultimately leads to heart disease characterized by right ventricular hypertrophy. Most of the pulmonary heart disease develops from bronchitis and obstructive emphysema, and a small part is related to bronchial asthma, tuberculosis, and bronchiectasis. Pulmonary heart disease exists all year round, more than respiratory and tract infections in winter and spring, leading to respiratory failure and heart failure, and the mortality rate is higher. The disease belongs to the category of "hepatitis syndrome", "sputum syndrome", "edema" and "drink syndrome" in Chinese medicine.

The patient suddenly loses consciousness and may be accompanied by generalized convulsions; the aorta beat disappears and the heart disappears; the breath is asthmatic or even stopped; the pupil is dilated.

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