Decreased ventricular fibrillation threshold
Introduction
Introduction In acute myocardial infarction, the threshold of ventricular fibrillation is significantly reduced. If there is a premature beat, it is easy to induce ventricular tachycardia or ventricular fibrillation. This is one of the electrophysiological mechanisms that cause coronary occlusion arrhythmias. The incidence of sudden coronary obstruction and arrhythmia is as high as 95%. The incidence is acute and the risk is dangerous. It can develop into ventricular fibrillation or cardiac arrest in a short time. The most common cause of coronary artery occlusion is acute thrombosis based on vascular stenosis caused by coronary atherosclerosis, resulting in a sudden blockage of the coronary arteries.
Cause
Cause
The most common cause of coronary artery occlusion is acute thrombosis based on vascular stenosis caused by coronary atherosclerosis, resulting in a sudden blockage of the coronary arteries. Coronary artery spasm, infective endocarditis, rheumatic heart disease, cardiomyopathy, thrombectomy, obstruction of coronary artery, coronary angiography can also cause vascular occlusion, transcatheter thrombosis, coronary artery injury, PTCA can also occur Coronary artery occlusion causes arrhythmia.
Examine
an examination
Related inspection
Electrocardiogram refers to pulse oxygen
1. Triggering activity: After coronary occlusion, the action potential of myocardial cells in the ischemic area stagnates in the 2-phase plateau, and there is a continuous rapid depolarization and repolarization. This oscillating potential change causes early post-depolarization, intracellular calcium. Ion overload, the formation of RonT phenomenon ventricular premature beats, can induce ventricular tachycardia, and even ventricular fibrillation. The membrane potential oscillation occurs after the action potential 3 phases, and the electrode is automatically depolarized again, which is called post-delay depolarization. After the early depolarization and the post-delay depolarization occur after the previous action potential, they are collectively referred to as the post-depolarization. They do not occur spontaneously and must be triggered by the previous action potential, also known as trigger activity. Triggering activity is considered to be the primary mechanism for the formation of coronary occlusion arrhythmias.
2, reentry phenomenon: After acute myocardial ischemia, the activation reversal along the reentry loop formed by the damaged cardiomyocytes and healthy cardiomyocytes, or the reversal of the loop reentry along the damaged area Purkinje cells and ventricular myocytes Form ventricular premature beats, ventricular tachycardia and ventricular flutter or ventricular fibrillation.
3. Injury current: The cardiomyocytes in the ischemic area cannot be depolarized or repolarized normally. There is a potential difference between the healthy cardiomyocytes and the healthy cardiomyocytes. When the damage current reaches the surrounding threshold potential level, the pacemaker cells are Depolarization can be performed early to form a new action potential, causing a premature beat or inducing ventricular tachycardia.
Diagnosis
Differential diagnosis
Differential diagnosis of ventricular fibrillation threshold reduction:
1. Assy syndrome: Adams-Stokes syndrome, or cardiogenic syncope, is caused by a sharp decrease in cardiac output, causing syncope and/or convulsions caused by acute cerebral ischemia.
2, cardiac arrest: cardiac arrest refers to the sudden termination of cardiac ejection function, aortic pulsation and heart sound disappear, important organs such as severe brain ischemia, hypoxia, leading to life termination. This unexpected sudden death is medically known as sudden death. The most common cause of cardiac arrest is ventricular fibrillation. If the patient is called without a response, the patient will be in a coma if there is no response to the pressure and the armpit. Then pay attention to observe the patient's chest and abdomen with or without undulating breathing. If there is no pulsation of the carotid artery and the femoral artery, the heartbeat can not hear the heartbeat, and the patient can be judged to have a cardiac arrest.
