I. What is premature heartbeat
Under normal conditions, the heart beat is dominated by the excitation from the sinus node, which is called sinus rhythm or normal heart rhythm. If a premature excitation in or around the atrioventricular node or any point in the ventricle other than the sinoatrial node causes the heart to beat prematurely, it is called premature beat. Clinically, premature heart beats can be classified as atrial, junctional, or ventricular.
However, having premature beats is not the same as having heart disease. Since the application of 24-hour ECG monitoring technology (HOLTER), it is possible to observe the fact that almost the majority of the population has a variable number of premature heart beats. Obviously, “most people have heart disease” does not correspond to the reality. Therefore, premature heart beats can also occur in normal individuals and at any age, and their chance of occurring increases with age.
The clinical manifestations of premature heart beats vary from person to person: they can be transient (e.g., overexertion, emotional stress, alcohol or coffee consumption) or persistent; they can occur at a frequency of only a few (episodic) to tens of thousands (frequent, di- or triple rhythm), singly, in pairs or >3 in a row on a 24-hour ambulatory electrocardiogram; they can be uncomfortable or accompanied by significant palpitations, chest tightness, shortness of breath, etc. Symptoms
Clinical significance of premature heartbeat
The clinical significance of premature heartbeat lies in
1. whether it occurs on the background of organic heart disease.
2. whether there is a potential to induce other arrhythmias. Functional premature beats are often physiological in nature, without a background of organic heart disease and without the potential to induce other arrhythmias, and are benign in nature. It does not cause hemodynamic changes, does not induce malignant arrhythmias, and poses no threat to the body, so in principle, no treatment is necessary.
Although organic premature beats are pathological, even if there is a background of organic heart disease, it depends on the situation whether other arrhythmias will be induced further. Because supraventricular tachycardia and atrial fibrillation induced by atrial and junctional premature beats are generally not fatal, only ventricular premature beats have the potential to induce malignant fatal arrhythmias such as ventricular tachycardia and ventricular fibrillation, so ventricular premature beats are often given more attention. Even so, ventricular premature beats can be functional or organic; or physiological or pathological; or benign or malignant.
Premature ventricular contractions are found in 1% of the normal population with standard ECG and in 40-75% of the healthy population with 24-48 hour ambulatory ECG. The incidence of ventricular premature beats increases with age, and a single 24-hour ambulatory ECG can record ventricular premature beats in more than 90% of subjects between the ages of 75 and 85 years.
The incidence of ventricular premature beats is 40% higher in men with organic heart disease than in women, and 60% higher in pairs of ventricular premature beats. At this time, careful observation and active treatment should be given.
Causes of premature heartbeat
There are many causes of premature beats. Neurological imbalance, including sympathetic and vagal nerves, as well as overexcitation and inhibition of the cerebral nerves are the most common causes of premature functional contractions. Imbalance of electrolytes such as potassium, sodium and magnesium and myocardial damage and ischemia are the most common causes of organic premature contractions. The former is mostly caused by coffee, tea, alcohol, smoking or emotional changes such as stress, anxiety, fear, happiness, sadness, anger or overwork, insomnia, menopause, or indigestion.
The latter mostly occurs in various heart diseases and electrolyte disorders, hyperthyroidism, mitral valve prolapse, etc. Premature heart beats can also be caused by surgery and certain medications. In patients with a background of organic heart disease, any additional infection, mood swings and physical exertion can lead to myocardial ischemia or increased impairment of cardiac function and induce various arrhythmias, including premature beats.
Misconceptions about premature heart beats in non-organic heart disease
If there is no background of organic heart disease, then it can be assumed that most of these premature beats are functional and have no important pathological significance. Due to the incorrect understanding of premature heart beats in non-organic heart disease, there are often some misconceptions in the diagnosis and treatment.
(1) Blindly searching for the cause and ignoring the presence of the causative factors.
(ii) Wrong diagnosis of heart disease, especially in the presence of premature ventricular contractions. Premature ventricular contractions are only an abnormal electrical activity of the heart and do not represent any cardiac lesion. However, they are often diagnosed as different heart diseases depending on the age of the patient, for example, adolescents are diagnosed with “myocarditis”, which leads to school suspension and long-term use of so-called myocardial drugs; middle-aged and elderly people are considered to have “coronary artery disease”; some non-cardiologists exaggerate the prognosis of the disease. The prognosis is poor, and patients are often told that cardiac accidents will occur if ventricular premature is not treated in a timely and effective manner, leading to a serious ideological burden and fear of patients and their families.
(3) Excessive use of antiarrhythmic drugs. Anti-arrhythmic drugs have the effect of correcting arrhythmias, but also often have adverse side effects such as aggravating or inducing new arrhythmias and decreasing myocardial contractility.
V. Correct treatment of premature heartbeat
In the face of premature heartbeat, we should first find out the nature, quantity and distribution characteristics of premature heartbeat and its background of organic heart disease, and especially, we should find out the causes and triggers of premature heartbeat. In patients with non-organic heart disease, the decision should be based on the characteristics and number of premature beats and related symptoms. For example, in the case of transient premature ventricular contractions, the patient should be warned to avoid the relevant precipitating factors and no medication is needed.
In patients with persistent premature ventricular contractions, if there are no uncomfortable symptoms, treatment can be withheld and echocardiography and ambulatory electrocardiography can be reviewed regularly. If the patient has obvious symptoms, firstly, it should be clarified whether the symptoms are related to ventricular premature, and secondly, the prognosis of ventricular premature should be explained to the patient to relieve their psychological pressure, and if necessary, anti-arrhythmic drugs of IB or IC class can be taken for a short time. Preferred β-blockers have also been advocated.
Recent literature reports that the number of ventricular premature >20% of total heart rate or total daily ventricular premature >20,000 may cause left ventricular enlargement. Frequent ventricular premature beats that fail to respond to pharmacological therapy may be treated by catheter ablation. Treatment of ventricular premature beats occurring in patients with critical organic heart disease such as myocardial infarction, cardiomyopathy, heart failure, hypokalemia and digitalis overdose often requires treatment under close observation by a physician under inpatient conditions.
In the treatment of premature contractions, anti-arrhythmic drugs are often a symptomatic treatment, and only treatment directed at the cause and causative factors is curative. A comprehensive treatment that addresses both the symptoms and the root cause is the preferred method of treatment for premature beats.