Overview.
Multiple atrial tachycardia (MAT), also known as disturbed atrial tachycardia (CAT), is a rare and distinctive atrial arrhythmia. Both adults and pediatrics can suffer from this type of atrial tachycardia, but they differ in etiology and other characteristics. In adults, it occurs mostly in older people over 65 years of age, with underlying disease, and is mainly characterized by an increased heart rate. In children, the underlying heart disease of atrial tachycardia can be congenital heart disease, cardiomyopathy, rheumatism and so on.
Causes
1. The most common causes in adults are as follows
(1) Chronic obstructive pulmonary disease (COPD), which accounts for 60% to 85% of all cases. Among them, chronic pulmonary heart disease is the most common.
(2) Heart failure Patients with MAT often have heart failure, which can be present in as many as 13% to 32% of cases. The hypoxia of heart failure and high levels of adrenaline in the blood. may promote MAT.
(3) Digitalis toxicity Especially pulmonary heart disease with digitalis toxicity is more likely to occur MAT, and often accompanied by varying degrees of atrioventricular block.
(4) Surgery, especially in those with a history of surgery with severe complications.
(5) Rare causes such as hypokalemia, pulmonary embolism, hypertensive heart disease, heart valve disease, sepsis, diabetes mellitus, mitral valve prolapse and other infections, metabolic disorders or aminophylline may aggravate the condition.
2. Common causes in children
(1) Immature development of cardiac conduction system After the birth of a newborn, the conduction system of the heart has a process of continuous development and maturation. During this process, changes in anatomy and histology and pathophysiology can easily lead to arrhythmia and sudden death in infants.
(2) Viral myocarditis Neonatal infection with Coxsackie virus may produce mild and reversible cardiac lesions that can lead to arrhythmias.
(3) The underlying heart disease in children with polygenic atrial tachycardia may be various congenital heart diseases, cardiomyopathies, and rheumatic diseases.
Symptoms
1. Adult patients
Most of them occur in the elderly over 65 years old, often accompanied by primary disease, the main manifestation is increased heart rate, mostly more than 100 beats / min. episodes of MAT can last minutes, hours, days, or even months, but often lasts up to 2 weeks to stop, or become sinus rhythm or become atrial fibrillation, atrial flutter, and often repeated. Sometimes the electrocardiogram shows alternating atrial fibrillation or atrial flutter.
2. Pediatric patients
The clinical features are different from those of adult patients:
(1) The age of onset is young: most of them are under 7 months old.
(2) The majority of children have concomitant respiratory tract infections.
(3) General condition is good after control of concomitant diseases, and no heart failure occurs.
(4) MAT is mostly persistent: it lasts for a long time. However, most of them can disappear on their own within 1 to 4 months.
(5) Electrocardiograms show transient atrial flutter in addition to MAT, while atrial fibrillation occurs rarely.
(6) The efficacy of antiarrhythmic drugs is not obvious.
(7) The prognosis is good: the mortality rate is very low.
(8) Symptoms in children are mainly respiratory symptoms, such as cough, shortness of breath, nasal irritation, irritability, moaning, and pallor. Other symptoms include vomiting, startled jumping, and fainting. Physical examination: there are obvious cardiac arrhythmia, muffled heart sounds, and pulmonary rales.
Examination
1. Electrocardiographic features of adult polygenic atrial tachycardia
(1) There are 3 or more P′ waves with different morphologies in the same lead, and the P′ waves are clearly visible. None of the P′ waves is considered predominant, i.e., there is no dominant pacing point.
(2) There was an equipotential line in the P′-P′ interval, and the P′-P′ interval and R-R interval were completely unequal.
(3) The P′-R intervals were unequal and variable.
(4) The atrial rate is 100-250 beats/minute, usually above 160 beats/minute, occasionally below 100 beats/minute.
(5) It is often accompanied by more obvious atrioventricular block, so the ventricular rate is also slower.
(6) Atrial excitation P′ waves can be transmitted down to the ventricle.
(7) The morphology of QRS waves is mostly within the normal range, and occasionally there may be waveforms of bundle branch block.
MAT is often accompanied by other types of atrial arrhythmias, which is one of the characteristics of ECG.
2. Pediatric polygenic atrial tachycardia ECG features
Basically the same as adults, but the pediatric atrial rate is faster, 140-300 beats per minute.
Diagnosis
The diagnosis can be made on the basis of history, symptoms, signs and ECG findings.
Treatment
The key to the treatment of MAT is the treatment of the underlying disease and the removal of the causative factors. Generally, with aggressive treatment, including anti-inflammatory, improvement of ventilation (pulmonary heart disease), correction of hypoxia and electrolyte disorders, and heart failure, the majority of patients can return to sinus rhythm with the improvement of the underlying disease, and the polygenic atrial tachycardia can also be restored to sinus rhythm. Digitalis, quinidine, procainamide, lidocaine, etc., have no significant efficacy on MAT. However, some people believe that digitalis has some efficacy, especially for those with heart failure. For those caused by digitalis intoxication, digitalis must be discontinued immediately.
1. Metoprolol (Metoprolol, Betalucil, Medocin) and verapamil (isobarbital) can inhibit atrial ectopic excitation foci, slow down atrioventricular conduction, slow down the ventricular rate of the MAT, and can be converted to sinus rhythm. Metoprolol is a β1-blocker, taken orally. It has little effect on the lungs and bronchi, but should still be contraindicated in those with bronchial asthma. Acute heart failure is prohibited.
2. Verapamil is effective orally and intravenously, taken orally or diluted in 5% dextrose solution and slowly pushed intravenously. It can slow down the heart rate of almost all patients, and about 43% of patients can return to sinus rhythm. There are adverse effects such as lowering blood pressure and aggravating heart failure.
3. Magnesium sulfate and potassium salt treatment also has some efficacy.