The difference between sudden cardiac death and myocardial infarction.

Written by Xie Zhi Hong
Cardiology
Updated on February 21, 2025
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Sudden cardiac death refers to the sudden death of a patient caused by various heart diseases. The most common causes include malignant arrhythmias such as ventricular fibrillation and ventricular tachycardia, severe bradycardia, significant valvular dysfunction, or the sudden occlusion of the coronary arteries leading to death. Myocardial infarction, on the other hand, refers to the sudden cessation of blood supply to the heart vessels, causing myocardial death and leading to arrhythmias or valvular dysfunction, which presents a range of symptoms in patients. Myocardial infarction can result in death in 30% of patients, but with medical intervention, the mortality rate can significantly decrease. Therefore, in cases of sudden cardiac death, the patients are already deceased. However, the mortality rate from myocardial infarction under natural circumstances is relatively high, reaching 30%. With current medical interventions, the rate of mortality due to sudden cardiac death can be reduced to less than 10%.

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Written by Chen Guang Yin
Cardiology
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What causes cyanosis of the face and lips in sudden cardiac death?

In patients with cardiogenic sudden death, we can see that their lips turn purple, commonly referred to as cyanosis of the lips. Similarly, their faces also turn purple. This primarily results from cardiac arrest caused by cardiogenic sudden death. Once the heart stops beating, the blood supply to the entire body, including the heart, brain, kidneys, peripheral vessels, face, skin, and fingers, is halted. This leads to a state of hypoxia. The purple discoloration (cyanosis) occurs because, after the heart stops, there is no blood flow and no oxygen exchange in the blood, ultimately leading to hypoxia.

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Written by Xie Zhi Hong
Cardiology
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The main cause of sudden cardiogenic cardiac arrest

70% of sudden cardiac deaths are caused by arrhythmias, often referred to as malignant arrhythmias, with the most common ones being ventricular tachycardia and ventricular fibrillation. A small portion is caused by severe bradycardia. This condition is generally seen in patients with structural heart diseases, such as acute myocardial infarction, severe dilated cardiomyopathy, hypertrophic cardiomyopathy, or patients in the late stages of valvular insufficiency or stenosis. It can also occur in patients with severe electrolyte disturbances, who are prone to malignant arrhythmias.

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Written by Xie Zhi Hong
Cardiology
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Does sudden cardiac death relate to coronary heart disease?

Some studies suggest that 70% of sudden cardiac deaths are caused by arrhythmias. Most of these arrhythmia-induced sudden deaths are associated with coronary artery atherosclerosis. Some are caused by acute myocardial infarction leading to sudden cardiac death. These are all caused by coronary heart disease. Therefore, sudden cardiac death is related to coronary heart disease. Thus, if coronary heart disease is suspected in a patient, it is crucial to perform early examinations and treatments to prevent the occurrence of myocardial infarction. Typical symptoms of coronary heart disease include intermittent chest tightness and chest pain, which can improve after a few minutes, and should therefore be taken seriously.

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Written by Zhang Yue Mei
Cardiology
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Does sudden cardiac death have a connection with overwork?

Sudden cardiac death is directly related to overexertion, particularly in individuals with coronary heart disease, congenital heart disease, rheumatic heart disease, viral myocarditis, and heart rhythm disorders, especially those accompanied by heart failure. Excessive strain can increase the burden on the heart, exacerbate heart failure, lead to arrhythmias, and in severe cases, result in sudden death. Therefore, patients with structural heart disease must follow a doctor's guidance to routinely use effective medications for treatment, rest adequately, avoid overexertion, and maintain a low-fat, low-salt diet to minimize factors that increase cardiac load and prevent the occurrence of sudden death.

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Written by Li Hai Wen
Cardiology
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Does sudden cardiac death have a relationship with hypertension?

Sudden cardiac death and hypertension are related, with the most common cause of sudden cardiac death being acute myocardial infarction, which leads to malignant arrhythmias, such as ventricular fibrillation, resulting in sudden cardiac death. In addition, severe aortic dissection can also cause sudden cardiac death, and hypertension is often an important cause of coronary heart disease, acute myocardial infarction, and aortic dissection. Long-term hypertension can lead to the occurrence of arteriosclerosis, resulting in the formation of arterial plaques or aneurysms, such as those occurring in the coronary arteries, causing coronary heart disease and myocardial infarction, or in the aorta, often leading to the formation of aortic aneurysms. When an aortic aneurysm ruptures, it can cause aortic dissection.