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What is premature beat, its mechanism and ECG characteristics?
In the process of heart beating, sometimes one or more ectopic beats occur in advance, which is called premature beat, also called premature beat, or premature beat for short. Premature beat is an active ectopic beat and one of the more common arrhythmias. ?
There are many reasons for premature beats. Some healthy people may also have premature beats in their hearts, which is more likely to happen in sick hearts. Healthy people often have some artificial incentives for premature beats, such as emotional excitement, full meal, overwork, upper respiratory tract infection, biliary tract diseases, electrolyte disorders, drug effects and so on. About 40% of premature beats occur in cardiovascular diseases, and the heart diseases prone to premature beats include coronary heart disease, hypertensive heart disease, rheumatic heart disease, mitral stenosis, cor pulmonale, myocarditis, cardiomyopathy and pericarditis. Other diseases leading to premature beats include hypothyroidism, anemia and hypokalemia. Various stimulating factors to the heart, such as cardiac catheterization, can cause atrial or ventricular premature beats due to direct stimulation to the heart wall; During cardiac catheterization, premature beats may occur when blood samples are taken too quickly or contrast media is injected into the heart chamber under pressure. During heart surgery, squeezing and pulling the heart, separating the valve and installing a pacemaker will all produce premature beats. Once these stimulating factors are eliminated, premature beats can disappear. The application of some drugs can also cause premature beats, especially digitalis drugs, others such as caffeine and isoproterenol. After stopping using these drugs, premature beats can disappear. ?
At present, there are three views on the mechanism of premature beats: one theory holds that there is an ectopic pacing point with enhanced excitability in the local area of myocardium, which is actively excited under the induction of some factors, so that the atrium or ventricle beats ahead of time; Another theory holds that part of the myocardium is still in the relative refractory period due to reentry, that is, when the sinus impulse drops, and the rest of the myocardium is excited and then transmitted to this part of the myocardium, this part of the myocardium can produce an early beat; There is also a view that there are active and rhythmic ectopic pacing points in myocardium, especially ventricular myocardium. ?
The * * * concentric electrogram of premature beats is characterized by one or two ectopic electrical excitation rhythms that appear in advance, and compensation intervals often occur due to interference with the normal rhythm of the next cycle, and a few are invasive. According to its frequency, it can be divided into occasional premature beats, multiple premature beats and frequent premature beats. Some frequent premature beats may have certain pairing rules, such as dichotomy and trisection; For example, there is a certain multiple relationship between consecutive premature beats in time, but there is no fixed coupling time relationship between them and normal rhythm. This kind of premature beat can occur in any part of the cardiac cycle, so it can produce atrial or ventricular fusion waves.
What is premature beat? What kinds are there?
Premature beats are also called premature beats. This is the most common arrhythmia. As the name implies, it is a kind of heartbeat that is issued in advance on the basis of normal heart rhythm.
Because premature contraction is based on sinus or ectopic rhythm, a certain point of the cardiac conduction system is excited prematurely, causing partial or total premature depolarization of the heart. This exciting point can be in atrium, atrioventricular junction, ventricular His-Putin system, and even sinus node. Therefore, it can be called atrial, atrioventricular junction, ventricular or sinus premature beats respectively.
Premature beats are very common, and it will inevitably not happen to anyone in this life. Generally speaking, the younger the age, the less common it is, and the older the age, the more common it is. The highest incidence rate is between 50 and 70 years old. About 5% of healthy people will have premature beats.
If you feel the pulse during premature beats, you will find that the pulse missed once. In fact, the heart beat once in advance, and then the interval is very long. The premature heartbeat is due to premature contraction of the heart, which reduces the amount of blood filled in the heart cavity and pumped into the aorta. The pulse wave can't be transmitted to the peripheral artery to cause the pulse condition, so the pulse condition falls off, which is the "knot pulse" that appears when TCM diagnoses the pulse.
Can premature beats affect health?
In clinical work, people often ask: Will "premature beats" affect health? As mentioned earlier, the beating of the heart is controlled by the sinoatrial node. Under normal circumstances, regular impulses from the sinoatrial node are transmitted to the atria and ventricles through the conduction system of the heart, thus driving the whole heart to beat. For some reason, the excitability of a certain part of myocardium in atrium or ventricle is too high, or there is something wrong with the conduction system, then premature beats and premature beats can suddenly appear in normal rhythm. This condition is called premature beat, also known as premature beat or premature beat and premature beat. According to the origin of premature beats, it can be divided into atrial premature beats, atrioventricular junction premature beats and ventricular premature beats. Ventricular premature beats are the most common, followed by atrial premature beats, and junctional premature beats are the least common. Premature beat is one of the most common arrhythmia. It has been reported that in asymptomatic normal people, 50% people have premature beats after 24 hours of continuous observation of dynamic electrocardiogram. After 48 hours of continuous observation, 70% ~ 80% people have premature beats. ?
Usually, when the heart is beating, you can't feel it. When premature beats occur, you can feel the heart beating because of the strong contraction of the ventricle; Because there is a pause after the premature beat, you can feel the heartbeat pause again. Everyone feels inconsistent, some say that the heart is fluctuating, some feel that the heart is about to jump out of the throat, and some are obviously flustered and uncomfortable. In addition, it may be accompanied by chest tightness, nausea, cough, dizziness and other discomfort. Some people even have frequent premature beats, but they don't have any feelings and symptoms, only when doctors auscultate or ECG. ?
The heart beats in an orderly and regular way, mainly pumping blood to meet the needs of various tissues and organs in the whole body. Premature beats, especially ventricular premature beats, will reduce cardiac output. But premature beats less than 6 times per minute have little effect on health. Occasional atrial premature beats only reduce coronary blood flow by 5%, and occasional ventricular premature beats by 65438 02%, both of which have no effect on cerebral circulation. Frequent premature beats of more than 6 times per minute are different. It can reduce coronary blood flow by about 25%, cerebral blood flow by 8% ~ 12% and renal blood flow by 8% ~ 10%, which has certain influence on health. However, the key is whether there is organic cardiovascular disease. If you have serious heart disease, frequent premature beats will lead to myocardial ischemia, angina pectoris or heart failure. Frequent atrial premature beats are often the signal of atrial fibrillation in patients with heart disease. Frequent ventricular premature beats can develop into ventricular tachycardia and even sudden death due to ventricular fibrillation. If there is no serious heart disease, even if premature beats often occur, it will not cause serious consequences. Clinically, functional or physiological premature beats are very common. Normal people can have premature beats when they are overworked, nervous, excited and anxious, or when they smoke a lot, drink alcohol, drink coffee or strong tea, or when they are resting or sleeping in bed. Constipation can occur in the elderly. This kind of functional premature beat can disappear after the induced cause is eliminated. After a comprehensive and in-depth inspection of the generator, no signs of heart disease were found. Some healthy people are very nervous and afraid after several premature beats, which in turn promotes the increase of premature beats. ?
Pathological premature beats are not uncommon. It occurs in various organic heart diseases or other pathological conditions, such as fever, anemia, hyperthyroidism, rheumatism, hypertension, hypokalemia, severe hypoxia or drug poisoning.
It can be said that the appearance of this premature beat is an important signal of myocardial ischemia and injury. For example, premature beats in patients with coronary heart disease and myocardial infarction often indicate severe myocardial ischemia; Premature beats in patients with rheumatic heart disease often suggest cardiac insufficiency; Premature beats in patients with hypertensive heart disease are usually related to ventricular hypertrophy and tension. ?
Generally speaking, premature beats in the elderly and children are often organic. If angina pectoris or heart failure occurs during premature beats, it must be organic. People with heart disease symptoms such as shortness of breath or enlarged heart, or people with coronary heart disease inducing factors (hypertension, hyperlipidemia, diabetes, obesity, family history, etc.). ) premature beats, mostly organic. ?
Organic premature beats have different effects on health and should be treated promptly and reasonably under the guidance of doctors.
What are the clinical manifestations and ECG characteristics of atrial premature beats?
Atrial premature beats are more common in normal people, and usually do not cause symptoms of consciousness or circulatory disorders. Sometimes patients complain of palpitations and chest tightness. Fatigue, anxiety, smoking, drinking, drinking strong tea and coffee, digitalis poisoning, atrial lesions, heart failure, myocardial ischemia and myocardial infarction can all cause atrial premature beats. Different diseases will lead to different accompanying symptoms. Cardiac auscultation can hear the sudden and early appearance of heartbeat, followed by extended compensation interval. The first heart sound of premature beats is louder than normal, the second heart sound is weak or inaudible, and the pulse of premature beats is weak or inaudible. ?
Its ECG features are as follows:
(1) p ′ wave appears in advance (p ′ wave can overlap with T wave of previous sinus beat). ?
(2)P′？ R interval is normal or slightly prolonged. ?
(3) The shape of P ′ wave is different from that of sinus P wave. ?
(4) QRS complex can be normal or abnormal after P ′. If abnormal QRS wave occurs, it is called atrial premature beat with indoor differential conduction. If there is no QRS wave in P wave, it is called atrial premature beat. On the same lead, if the shape and pairing interval of P ′ are different, it is called multi-source atrial premature beats. ?
(5) There is often an incomplete compensation interval, that is, the time between two normal P waves, including atrial premature beats, is shorter than twice the normal PP spacing.
What are the clinical manifestations and ECG characteristics of ventricular premature beats?
Before the sinus node impulse reaches the ventricle, any part of the ventricle or the ectopic rhythm point of the ventricular septum sends out electrical pulses in advance to cause the depolarization of the ventricle, which is called ventricular premature beat, or ventricular premature beat for short. ?
In normal people, general factors can induce ventricular premature beats, such as smoking, drinking strong tea, drinking alcohol, emotional tension, fatigue, indigestion, hypokalemia, hyperthyroidism, taking certain drugs and so on. Some can't even find any reason. Among organic heart diseases, coronary heart disease, rheumatic heart disease, hypertensive heart disease, myocarditis, cardiomyopathy and mitral valve prolapse are the most common. ?
Ventricular premature beat is a common arrhythmia, and patients often complain of palpitation and chest "impact". Most of them can be diagnosed by auscultating the heart. The first heart sound of premature beats is brighter than the normal first heart sound, and the second heart sound is weak or inaudible. These characteristics are the same as atrial premature beats, but the compensatory interval after ventricular premature beats is longer and belongs to complete compensatory interval. If ventricular premature beats occur frequently, it is sometimes difficult to distinguish them from atrial fibrillation, and patients can be allowed to move. If the patient's heart rate increases and the rhythm tends to be regular after physical activity, the possibility of ventricular premature beats is greater, because the sinus frequency increases after human activity, which overcomes the display of ectopic heart rhythm. If there is a ventricular premature beat after every normal heartbeat, it will form a binary law, which is more common in digitalis poisoning than the binary law caused by digitalis poisoning, and often suggests organic heart disease. Ventricular premature beats are more common in normal people. To judge the nature of ventricular premature beats, we must make a comprehensive analysis. If premature beats are caused by smoking, drinking and other incentives, they are mostly functional and generally do not need treatment. Ventricular premature beats caused by organic diseases should be treated according to the specific conditions of patients. ?
The electrocardiogram of ventricular premature beats has the following points:
(1) wide QRS complex appeared earlier, and the QRS complex interval was longer than 0. 1 1 s, and there was no early P wave before. ?
(2)P wave can appear in ST segment or be buried in QRS and T wave, and the R-P time is often 0. 12 ~ 0.20 seconds, and the advance of P wave has nothing to do with QRS wave. ?
(3) The direction of 3)ST segment and T wave is often opposite to that of QRS wave. ?
(4) There is usually a complete compensatory interval (that is, the interval between two sinus beats before and after premature beats is twice as long as the normal cardiac cycle). ?
(5) Sometimes ventricular premature beats are sandwiched between two consecutive sinus premature beats, which is called meta or inserted ventricular premature beats. ?
(6) Sometimes, dichotomy, trisection or premature ventricular beats form short bursts of ventricular tachycardia. ?
(7) Multiple ventricular premature beats can be seen on the same lead, and the forms of ventricular premature beats are different.
How to judge the dangerous degree of ventricular premature beats
General ventricular premature beats are definitely not life-threatening, so don't worry too much. But sometimes frequent ventricular premature beats, especially the R wave of the early wave falls on the T wave of the previous beat, that is, RonT, then ventricular tachycardia will occur, and even develop into ventricular fibrillation, which will be life-threatening. For ventricular premature beats, Lown's divides them into several grades. The higher the grade, the greater the risk of sudden death, especially in patients with acute myocardial infarction. Lown is classified in the United States as follows:
Grade 0: No ventricular premature beats. ?
Grade I: ventricular premature beats < 30 beats/hour. ?
Grade Ⅱ: ventricular premature beats > 30 beats/hour. ?
Grade ⅲ: polymorphic ventricular premature beats. ?
Grade ⅳa: Paired premature beats. ?
Grade ⅳ b: ventricular tachycardia. ?
Grade ⅴ: Ventricular premature beats (Ron T) with R wave falling on T wave. ?
Recently, many studies have found that the number of ventricular premature beats increases with age. Most experts believe that Lown classification is only applicable to ventricular arrhythmia in patients with myocardial infarction. This is mainly because Ron T's ventricular premature beats can often be detected in some healthy people, but they do not cause ventricular tachycardia or ventricular fibrillation. Ron T phenomenon can appear in ECG of patients with pacemaker, but it has not been found to cause ventricular tachycardia or ventricular fibrillation. At present, more and more studies show that the risk of ventricular premature beats is mainly judged by the following points: (1) Basic heart disease, such as severe myocardial infarction, severe ischemia, myocarditis or ventricular aneurysm; (2) Cardiac function; (3) Whether the electrolyte is disordered. Ventricular premature beats in patients with good cardiac function and no organic heart disease generally belong to benign arrhythmia. Patients with severe organic heart disease and obviously impaired cardiac function, such as ventricular premature beats ≥ ⅲ, are considered to be arrhythmia, with high risk and possibility of sudden death.
What should I do if patients have ventricular premature beats after myocardial infarction?
Traditionally, it is believed that if patients with myocardial infarction have ventricular premature beats, they may cause fatal ventricular arrhythmias, such as ventricular tachycardia and ventricular fibrillation. Whether ventricular premature beats affect the prognosis of patients after acute myocardial infarction, and to what extent, recent research shows that antiarrhythmic treatment of asymptomatic ventricular premature beats after myocardial infarction can effectively control ventricular premature beats, but it cannot prevent sudden cardiac death. At present, there are many viewpoints in the world:
(1) If patients have no symptoms of ventricular premature beats and arrhythmia has no effect on prognosis, there is no need to deal with arrhythmia in these patients. ?
(2) If there is ventricular premature beat, the patient is asymptomatic, but arrhythmia has an impact on the prognosis. Such patients should first correct heart failure and deal with the primary disease according to the basic cause. You can use some antiarrhythmic drugs, such as β? Blocker. (3) Patients with ventricular premature beats and symptoms, but arrhythmia has no effect on prognosis, can be operated or ablated if they are young;
For patients with symptoms but no recurrence or aggravation of ischemic heart disease, antiarrhythmic drugs should be carefully selected to prevent heart disease caused by drugs.
Dysrhythmia, or other side effects make the condition worse. ?
(4) If ventricular premature beats have symptoms and premature beats have an impact on the prognosis, cardiac electrical program stimulation should be given to screen antiarrhythmic drugs. If the electrical program stimulation can no longer induce monomorphic persistent ventricular tachycardia after taking the drug, it means that the drug is effective. The application of this medicine can reduce the probability of sudden cardiac death in patients. However, some people advocate removing or destroying the arrhythmia focus by surgery or ablation. For patients who cannot accept these treatment measures, an antiarrhythmic pacemaker can be implanted.
How to treat functional ventricular premature beats
Ventricular premature beats found in clinic are called functional ventricular premature beats if there is no evidence to prove that they have abnormal heart and extra-cardiac reasons. Simply speaking, it is a normal premature ventricular contraction, which belongs to benign arrhythmia. In the normal population, the incidence of functional ventricular premature beats is 50% ~ 70%. ? To ensure that ventricular premature beats are functional, we must first exclude all kinds of organic heart diseases and choose appropriate examinations, including physical examination, electrocardiogram, dynamic electrocardiogram, exercise experiment, ventricular late potential, cardiac B-ultrasound and cardiac radionuclide examination. When there are special needs, we can use cardiac electrophysiological examination, coronary angiography and ventriculography. Secondly; In addition, we should rule out the causes that can induce ventricular premature beats, such as electrolyte disorder, drug influence, hyperthyroidism and other systemic diseases. In addition, it is to analyze and judge the early level of the laboratory, and the American Lown grading standard is often used for grading. But at present, most experts think that Lown grading standard is limited to patients with organic heart disease, which is relatively meaningless to normal people. Up to now, there is still no reasonable ECG grading standard suitable for normal ventricular premature beats. ?
For functional ventricular premature beats, some people can be calm, while others are anxious, panic and irritable, and try their best to find a doctor to prescribe some antiarrhythmic drugs. Some clinicians confuse functional ventricular premature beats with organic ventricular premature beats, exaggerating their harm, and prescribing some second-and third-line drugs to some patients with better control room premature beats but greater side effects. Blindly pursuing the disappearance of premature beats and blindly increasing the dosage of drugs or combining drugs. The above practices do more harm than good, increase the mental burden of patients, cause the abuse of antiarrhythmic drugs, and increase the number of cases of arrhythmia caused by antiarrhythmic drugs. ?
In principle, patients with functional ventricular premature beats cannot receive treatment. If there are obvious symptoms, sedatives should be used to reduce adverse stimuli (such as quitting smoking, drinking less tea or coffee), and low-dose β -blockers such as betaloc and aminoacylpropranolol can also be used for treatment.
Do ventricular premature beats need treatment? Which ventricular premature beats need treatment? How to treat them?
Ventricular premature beat is the most common arrhythmia, which can occur in normal people and various heart diseases. Whether ventricular premature beats need treatment depends mainly on the etiology. If it happens to normal people, it is often induced by emotional excitement, mental tension, excessive fatigue, indigestion, smoking, drinking strong tea or coffee. If there are no obvious symptoms, medical treatment is unnecessary. If the patient's symptoms are obvious, the treatment should aim at eliminating the symptoms. Relieve patients' anxiety and anxiety and avoid inducing factors, such as smoking, coffee and stress. Drugs should be beta blockers or mexiletine, and class I, class C and class III antiarrhythmic drugs should be avoided as far as possible.
Ventricular premature beats caused by organic heart disease are common in patients with coronary heart disease, cardiomyopathy, rheumatic heart disease and mitral valve prolapse. If the following conditions appear on ECG, it is suggested that ventricular premature beats are pathological: ① Multi-source ventricular premature beats. ② Paired or persistent ventricular premature beats. (3) Ventricular premature beats appear on the T wave of precordial beats (RonT phenomenon), and the coupling interval is less than 0.40 seconds. The above three conditions are often easy to induce ventricular tachycardia or ventricular fibrillation, and must be dealt with in time. ④ Extra-wide ventricular premature beats with ④QRS interval ≥0.6 seconds. ⑤ Ultra-short ventricular premature beats, that is, the amplitude of QRS complex of ventricular premature beats in each lead is ≤1.0mv ⑤ The QRS complex of ventricular premature beats has obvious notch, and the ascending or descending branches are irregular. ⑦ The T wave of ventricular premature beats is sharp and the two branches are symmetrical. The direction of T wave is consistent with the main wave direction of QR S wave, and the ST segment changes horizontally. ⑧ Ventricular premature beats with heart rhythm. Pet-name ruby premature beat index is less than 1. ? μ ventricular premature beats appear on myocardial ischemia or myocardial infarction map.
The treatment of pathological ventricular premature beats should first be based on the etiology, and premature beats often decrease or disappear with the improvement of basic diseases. If the symptoms are obvious, you can choose the following drugs for treatment:
① Lidocaine, procainamide and bromobenzylamine are effective for ventricular premature beats. Especially acute myocardial infarction with ventricular premature beats.
② Beta blockers, phenytoin sodium, quinidine, verapamil, etc. It is effective for all kinds of premature beats. People with bronchial asthma should not use β? Blocker.
③ Patients with bradycardia and premature beats can be treated with atropine.
④ Digitalis drugs: effective for premature beats caused by heart failure. The premature beats caused by digitalis poisoning can be controlled by giving potassium chloride and phenytoin sodium in addition to stopping digitalis drugs.
⑤ The incidence of sudden cardiac death is higher after myocardial infarction or cardiomyopathy, especially when the left ventricular ejection fraction is obviously decreased, the risk of sudden cardiac death will be greatly increased. The total cardiovascular mortality increased significantly after using some antiarrhythmic drugs to treat premature ventricular death and myocardial infarction. The reason is that these antiarrhythmic drugs themselves have the effect of causing arrhythmia. Therefore, we should avoid using class I drugs to treat ventricular premature beats after myocardial infarction. β? Blockers can reduce the incidence of sudden death after myocardial infarction, although the effect on ventricular premature beats is not significant. Amiodarone is effective in inhibiting ventricular premature beats, but attention should be paid to the possibility of torsional ventricular tachycardia.