In the process of heart beating, sometimes one or several 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 arrhythmia. ?
There are many reasons for premature beats. Some healthy people's hearts may also have premature beats, which are more likely to occur in diseased 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, pulmonary heart disease, myocarditis, cardiomyopathy and pericarditis. Other diseases that cause premature beats include hypothyroidism, anemia and hypokalemia. Various irritating factors to the heart, such as cardiac catheterization, can cause atrial or ventricular premature beats due to direct stimulation to the heart wall; Premature pulsation can occur during cardiac catheterization, or taking blood samples too quickly, or injecting contrast media into the heart cavity quickly under pressure. Premature beats can be produced by pressing and pulling the heart, separating the valve and installing a pacemaker during heart surgery. 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, etc. When these drugs are stopped, 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 increased excitability in the local area of myocardium, which is actively excited under the induction of some factors, making the atrium or ventricle beat ahead of schedule; Another theory holds that a part of myocardium is still in a relative refractory period due to reentry, that is, when sinus impulse descends, and when the rest of the myocardium is excited and then transmitted to this part of myocardium, this part of myocardium can produce an early beat; There is also a view that there is an active and rhythmic ectopic pacing point in myocardium, especially in ventricular myocardium. ?
The * * * concentric electrogram of premature beats is characterized by single or two ectopic rhythms of electrical excitation that appear in advance, and compensation intervals often occur due to interference with the normal rhythm of the next cycle, and a few are intrusive. It can be artificially divided into occasional premature beats, multiple premature beats and frequent premature beats according to their frequency. Some frequent premature beats may have certain pairing rules, such as the binary law and the triple law; For example, there is a certain multiple relationship in time between successive premature beats, but there is no fixed coupling time relationship between them and normal rhythm. Such premature beats can occur at any part of the cardiac cycle, so atrial or ventricular fusion waves can be generated.
What is premature contraction? What kinds are there?
Premature contraction is also called premature beat, or premature beat for short. It is the most common arrhythmia. As the name implies, it is a kind of heartbeat that is sent out early on the basis of normal heart rhythm.
Because premature contraction is based on sinus or ectopic rhythm, a certain point in the cardiac conduction system is excited early, which causes a depolarization of part or all of the heart prematurely. This exciting point can be in atrium, atrioventricular junction, His-Pukinje system of ventricle, and even in sinoatrial node. Therefore, it can be called atrial, atrioventricular junction, ventricular or sinus premature contraction respectively.
Premature beats are very common, and it is inevitable that anyone will not happen in his life. Generally speaking, the younger the age, the rarer it is, and the older it is, the more common it is. Its highest incidence is between 50 and 70 years old. About 5% of healthy people can have premature beats.
If you feel the pulse when you have premature beats, you will find that the pulse is missed once, but actually the heart beats once in advance, and then there is a long interval. The early heartbeat is due to the premature contraction of the heart, which reduces the blood volume filled in the heart cavity and the blood volume pumped into the aorta. The pulse wave cannot be transmitted to the peripheral arteries to cause the pulse, so the pulse falls off, which is the "knot pulse" that appears when the pulse is diagnosed in traditional Chinese medicine.
Can premature beats affect health?
In clinical work, people often ask: Can "premature beats" affect health? As mentioned earlier, the beating of the heart is under the command of the sinoatrial node. Under normal circumstances, the regular impulse from the sinoatrial node is transmitted to the atrium and ventricle 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 the conduction system is out of order, then premature excitation and contraction can suddenly appear in the normal rhythm. This situation is called premature beat, also known as premature beat or premature contraction and premature contraction. According to the origin of premature beats, it can be divided into atrial, atrioventricular junction 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% of them 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 gap after premature beat, you can feel the heartbeat pause again. Everyone feels inconsistent, some say that the heart swings, some feel that the heart wants 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 have no feelings and symptoms, and they are only found when doctors auscultate or ECG. ?
The orderly and regular beating of the heart is mainly to pump blood to meet the needs of tissues and organs all over the body. Premature beats, especially ventricular premature beats, can reduce the cardiac output. However, premature beats less than 6 times per minute have little effect on health. Occasional atrial premature beats reduced coronary blood flow by only 5%, and occasional ventricular premature beats decreased by 12%, both of which had no effect on cerebral circulation. Frequent premature beats 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 will have a certain impact on health. However, the key is whether there is organic cardiovascular disease. If there is 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 heart patients, and frequent ventricular premature beats can develop into ventricular tachycardia or even sudden death due to ventricular fibrillation. If there is no serious heart disease, even if premature beats occur frequently, 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 drink strong tea, or when they are resting or sleeping in bed. The elderly can occur after constipation. This kind of functional premature beat can disappear after the induced cause is removed. There is no evidence of heart disease after a comprehensive and in-depth examination of the generator. 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 certain 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 suggest severe myocardial ischemia; Premature beats in patients with rheumatic heart disease often suggest cardiac insufficiency; Premature beats in patients with hypertensive heart disease are often related to ventricular hypertrophy and strain. ?
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 who have symptoms of heart disease such as shortness of breath or heart enlargement, or who have predisposing factors of coronary heart disease (hypertension, hyperlipidemia, diabetes, obesity, family history, etc.) have 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 mostly found in normal people, and usually do not cause conscious symptoms, nor do they cause circulatory disorders. Sometimes patients can complain of palpitations and chest tightness. Fatigue, anxiety, smoking, drinking, drinking strong tea and coffee, digitalis poisoning, atrial lesion, heart failure, myocardial ischemia and myocardial infarction can all cause premature atrial contraction. Different diseases can lead to different accompanying symptoms. Cardiac auscultation can hear the sudden and early appearance of heartbeat, followed by prolonged compensatory 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 invisible. ?
Its ECG features are as follows:
(1) The P ′ wave appears in advance (the P ′ wave can be superimposed on the T wave of the 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 there is abnormal QRS wave, it is called atrial premature beat with indoor differential conduction. If there is no QRS wave in P wave, it is called premature atrial transmission. On the same lead, if the shape and pairing interval of P ′ are different, it is called multi-source premature atrial contraction. ?
(5) There are often incomplete compensatory intervals, 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 an electrical impulse in advance to cause the depolarization of the ventricle, which is called premature ventricular contraction, or premature ventricular contraction for short. ?
In normal people, ventricular premature beats can be induced by general factors, such as smoking, drinking strong tea, drinking alcohol, emotional tension, fatigue, indigestion, hypokalemia, hyperthyroidism, taking certain drugs, etc., and some even can't 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 "impact feeling" in the chest. Most of them can be diagnosed when the heart is auscultated. 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 premature ventricular beats occur frequently, which is sometimes difficult to distinguish from atrial fibrillation, patients can be allowed to move. If the heart rate of patients increases and the rhythm tends to be regular after physical activity, the possibility of premature ventricular beats is greater, because the sinus frequency increases after human activity, which overcomes the display of ectopic heart rhythm. If every normal heartbeat is followed by a ventricular premature beat, it will form a binary law, which is more common in digitalis poisoning, not 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 some incentives such as smoking and alcohol, they are mostly functional and generally do not need treatment. For premature ventricular contractions caused by organic diseases, treatment should be given according to the specific conditions of patients. ?
The electrocardiogram of ventricular premature beats has the following points:
(1) The wide QRS complex that appears in advance, the QRS wave interval is greater than 0. 1 1 s, and there is no premature P wave before it. ?
(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 P wave has nothing to do with QRS wave in advance. ?
(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 beats, which is called meta or inserted ventricular premature beats. ?
(6) Sometimes, binary law, triple law, or premature ventricular beats form short bursts of ventricular tachycardia. ?
(7) On the same lead, multi-source ventricular premature beats can be seen, and the shapes of ventricular premature beats are different.
How to judge the dangerous degree of premature ventricular contraction?
General ventricular premature beats are certainly 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, and then ventricular tachycardia will occur, even develop into ventricular fibrillation, which will be life-threatening. For ventricular premature beats, Lown's divides it into several grades, and the higher the grade, the greater the risk of sudden death, especially for patients with acute myocardial infarction. The classification of Lown in the United States is 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 with R wave falling on T wave (Ron T). ?
Recently, many studies have found that the number of ventricular premature beats increases with age. Most experts believe that Lown's classification is only suitable for 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 none of them cause ventricular tachycardia or ventricular fibrillation. Ron T phenomenon can appear in ECG of patients with pacemaker, but it has not been found that it can 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 diseases, such as severe myocardial infarction, severe ischemia, myocarditis or ventricular aneurysm; (2) state of 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 as arrhythmia with high risk and possibility of sudden death.
What should I do if the patient has ventricular premature beats after myocardial infarction?
Traditionally, it is believed that if patients with myocardial infarction have ventricular premature beats, they may trigger fatal ventricular arrhythmias, such as ventricular tachycardia and ventricular fibrillation. Whether ventricular premature beats have any influence on the prognosis of patients after acute myocardial infarction, and to what extent, recent studies have shown that anti-arrhythmia treatment for asymptomatic ventricular premature beats after myocardial infarction can effectively control ventricular premature beats, but it can not prevent the occurrence of sudden cardiac death. At present, there are many opinions in the world:
(1) If the patients have asymptomatic ventricular premature beats and the arrhythmia has no effect on the prognosis, it is unnecessary to deal with the arrhythmia of these patients. ?
(2) If there are ventricular premature beats and the patients are asymptomatic, but arrhythmia has an impact on the prognosis, these patients should first be treated with the basic cause, correct heart failure and deal with the primary disease. Some antiarrhythmic drugs can be used, such as β? Blocker. (3) Patients with premature ventricular contractions and symptoms, but arrhythmia has no effect on prognosis, if they are young, they can be operated or ablated;
For patients with symptoms but no recurrence or aggravation of ischemic heart disease, antiarrhythmic drugs should be carefully selected to prevent the drug from causing heart disease.
Dysrhythmia, or bring other side effects to make the condition worse. ?
(4) If premature ventricular 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 monomorphic sustained ventricular tachycardia is no longer induced by electrical program stimulation after taking the drug, it shows that the drug is effective. The application of this medicine can reduce the chance of sudden cardiac death in patients. However, some people advocate that the focus of arrhythmia should be removed or destroyed by surgery or ablation. For patients who cannot accept these treatment measures, anti-arrhythmia pacemakers 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 extracardiac causes. Simply put, it is premature ventricular contraction that can occur in normal people, and it belongs to benign arrhythmia. In the normal population, the incidence of functional premature ventricular beats is 50% ~ 70%. ? To ensure that ventricular premature beats are functional, we should 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; Besides, the inducement that can induce premature ventricular contraction, such as electrolyte disorder, drug influence, hyperthyroidism and other system diseases, should be excluded. In addition, it is the level of analysis and judgment room early, which is often graded by American Lown grading standard. However, at present, most experts believe that the 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, panicked and cranky, 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 its harmfulness, and prescribe some second-and third-line drugs for 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 premature ventricular contractions can not be treated. If there are obvious symptoms, sedatives should be used to reduce adverse stimuli (such as quitting smoking and drinking less tea or coffee), and small doses of beta blockers, such as betaloc and aminoacyl-propranolol, can also be used for treatment.
Do all 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, medication is not necessary. 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, stress, etc. The drugs should be β blockers or mexiletine, and class I C and 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 continuous ventricular premature beats. (3) Ventricular premature beats appear on the T wave of anterior cardiac beats (i.e. 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 QRS interval ≥0.6 seconds. ⑤ Extra-short ventricular premature beats, that is, the amplitude of QRS complex of ventricular premature beats in each lead is ≤1.0mv.. ⑥ 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 Concurrent ventricular premature beats with heart rhythm. Pet-name ruby premature beat index is less than 1. ? μ Ventricular premature beats appearing on the graph with myocardial ischemia or myocardial infarction.
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. are 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 high after myocardial infarction or cardiomyopathy, especially when the left ventricular ejection fraction decreases obviously, the risk of sudden cardiac death will increase greatly. Using some antiarrhythmic drugs to treat ventricular premature death and total cardiovascular mortality after myocardial infarction increased significantly. The reason is that these antiarrhythmic drugs themselves have arrhythmia-causing effects. Therefore, the treatment of ventricular premature beats after myocardial infarction with class I drugs should be avoided. β? Blockers can reduce the incidence of sudden death after myocardial infarction, although the effect on premature ventricular contraction is not significant. Amiodarone is effective in inhibiting ventricular premature beats, but attention should be paid to the possibility of torsional ventricular tachycardia.
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