Overview of tachycardia
A group of tachycardia disorders that originate in the atrial tissue and do not require the involvement of the AV node for maintenance.
Dizziness, fatigue, palpitations, chest pain, and chest tightness can occur.
Can be caused by cardiopulmonary disease, cardiac surgery, digitalis toxicity, etc.
Treatment includes medication, electrical cardioversion, and interventional catheter ablation.
Definition
Atrial tachycardia, or atrial tachycardia for short, is a cardiac arrhythmia characterized by fast-frequency atrial activity with excitation originating and maintained in the atria.
Atrial tachycardia is a relatively rare arrhythmia, accounting for about 5% of paroxysmal supraventricular tachycardias [1-3].
Classification
Atrial tachycardia can be categorized into focal atrial tachycardia and multisource atrial tachycardia, depending on the point of origin.
Focal atrial tachycardia
The impulse signaling pattern originates in a very small, confined area of the atria.
Polygenic atrial tachycardia
Also known as disordered atrial tachycardia.
There are multiple points of origin of impulse signals within the atrial tissue.
It is a common arrhythmia in severe pulmonary disease and may eventually progress to atrial fibrillation [4].
Morbidity
Atrial tachycardia accounts for approximately 5% to 15% of all supraventricular tachycardias.
Atrial tachycardia can be seen at any age with no known racial or gender predisposition.
Etiology
Causes
Cardiopulmonary disease
Cardiopulmonary diseases such as coronary artery disease, cardiomyopathy, pulmonary heart disease, and chronic obstructive pulmonary disease may damage the normal heart conduction system and cause the disease.
Heart Surgery
Surgical scarring resulting from cardiac surgery or catheter ablation can also damage the normal heart conduction system and cause atrial tachycardia.
Other factors
Digitalis intoxication, heavy alcohol consumption, and various metabolic disorders (e.g., hyperthyroidism, electrolyte disorders, hypoxia, etc.) can be the cause of atrial tachycardia.
Pathogenesis
Abnormal impulse frequency and abnormal impulse conduction are the two basic pathogenetic mechanisms leading to atrial tachycardia.
Impulse frequency abnormalities
Increased autoregulation: Accelerated 4-phase automatic depolarization of normal and abnormal autoregulatory cells, increased autoregulation, and increased impulse frequency can lead to the onset of tachycardia.
Triggered activity: triggered activity can be seen in the atrial tissue, where a slow depolarizing wave follows a spontaneously excited action potential, which when it reaches the threshold potential can cause another action potential, leading to an impulse frequency that causes tachycardia.
Impulse conduction abnormalities
Two or more conduction pathways may be present in the impulse conduction system, such as the sinus node and atrial myocardium, which may close proximally and distally to form a closed loop.
Myocardial impulses are conducted through the two pathways with unequal velocities and periods of inappropriateness, allowing the impulses to conduct through the nonblocked channels long enough to bring the unidirectionally blocked pathways out of their periods of inappropriateness.
The impulses cycle repeatedly through the loop, producing a sustained and rapid arrhythmia [5-6].
Symptoms
Major Symptoms.
Some patients may have no clinical symptoms, while some may present with the following symptoms, which may be in the form of transient, intermittent episodes or may manifest as persistent episodes.
Dizziness and fatigue
Patients may have dizziness, weakness, generalized weakness and poor mental status.
In severe cases, blackouts or even fainting may occur.
Palpitations
Patients often experience rapid heartbeat and feel discomfort in the heart area.
Chest pain
Due to myocardial ischemia, angina pectoris may occur, which manifests as a squeezing-like boring pain in the anterior region of the heart.
Chest tightness
Patients may experience chest tightness, which is aggravated by activity, and in severe cases, shortness of breath or dyspnea may occur.
Complications
Atrial fibrillation
Atrial fibrillation may be induced in patients with atrial tachycardia, especially in patients with polygenic atrial tachycardia.
Patients may experience palpitations, chest pain, chest tightness, and other symptoms, and may show signs such as unequal strength of the first heart sound, absolute irregularity of the heart rhythm, and a short pulse.
Atrial fibrillation is prone to thrombosis, leading to embolism in various parts of the body, and needs to be taken seriously.
Heart Failure
When atrial tachycardia lasts for a long time, it will lead to myocardial ischemia and induce heart failure.
The patient may have obvious dyspnea, sitting breathing, pink foamy sputum and other symptoms.
Heart failure can lead to systemic circulatory failure and even lead to sudden death, endangering the patient’s life.
Asperger’s Syndrome
Severe atrial tachycardia may lead to a significant reduction in cardiac output and insufficient perfusion of brain tissue, resulting in ischemia and hypoxia of brain tissue, inducing Asperger’s syndrome.
Patients may experience acute cerebral ischemia symptoms such as pallor, blackout, syncope, transient impairment of consciousness, and some patients may experience convulsions and urinary and fecal incontinence.
As syndrome can lead to acute cerebrovascular accidents and even lead to sudden death.
Sudden cardiac death
Severe atrial tachycardia can cause significant reduction of cardiac output, leading to insufficient myocardial perfusion, inducing ventricular fibrillation and other malignant arrhythmias, and even directly leading to cardiac arrest, causing sudden cardiac death.
Patients may experience severe chest pain, severe dyspnea, loss of consciousness and other manifestations.
Sudden cardiac death can lead to rapid death of the patient [7-8].
Consultation
Department of Medicine
Cardiology
Prompt medical attention is recommended when the patient develops symptoms such as dizziness, weakness, palpitations, chest pain, and chest tightness.
Prompt medical attention is recommended when the patient’s physical examination reveals atrial tachycardia.
Emergency Department
If the patient develops critical conditions such as blackout, syncope, loss of consciousness, severe chest pain, severe respiratory distress, respiratory arrest, etc., he/she should immediately consult the Emergency Department or call 120 emergency number for emergency services.
Preparation for medical treatment
Consultation: Registration, Preparation of Information, Frequently Asked Questions
Tips for seeking medical treatment
Do not use antiarrhythmic drugs on your own without the guidance of a specialist, as this may aggravate your condition and affect the diagnosis and treatment.
Preparation List
Symptom list
Time of onset of symptoms, special manifestations, etc.
Are there symptoms such as dizziness, weakness, palpitations, chest pain, chest tightness, etc.?
How long have these symptoms been present?
Are there any triggers for the onset of symptoms? Are there any sudden stops?
What is the frequency of the attacks and the duration of each attack?
Medical history
Any previous history of cardiopulmonary disease such as coronary heart disease, cardiomyopathy, pulmonary heart disease, chronic obstructive pulmonary disease, etc.?
Any previous cardiac surgery or catheter ablation?
Did you drink a lot of alcohol before the onset of the disease?
Have you had regular medical checkups? What is the status of previous electrocardiograms?
Checklist
Results of tests in the last six months, which can be brought to the doctor’s office
Electrocardiogram or ambulatory electrocardiogram.
Laboratory tests: cardiac enzymology, troponin, blood B-type natriuretic peptide (BNP) or N-terminal B-type natriuretic peptide proteins (NT-ProBNP), blood lipids, blood glucose, etc.
Imaging tests: cardiac ultrasound, etc.
List of medications
Medication used in the last 3 months, such as medication or packaging, can be brought to the doctor’s office
Digitalis: e.g. Digoxin.
Anti-arrhythmic drugs: e.g. metoprolol, bisoprolol, amiodarone, verapamil, etc.
Bronchodilators: e.g. salbutamol, aminophylline, etc.
Diagnosis
Diagnosis is based on
Medical history
Pre-existing cardiopulmonary disease such as coronary artery disease, cardiomyopathy, pulmonary heart disease, chronic obstructive pulmonary disease, etc. may be present.
Cardiac surgery such as cardiac surgery, catheter ablation, etc. may have been performed prior to the onset of the disease.
There may be digitalis intoxication and heavy alcohol consumption before the onset of the disease.
Clinical manifestations
Symptoms
Some patients may be asymptomatic.
Some patients may have symptoms such as dizziness, weakness, palpitations, chest pain, chest tightness, and other symptoms.
Physical signs
Increased heart rate.
The first heart sound may vary in intensity on cardiac auscultation.
Some patients may have a drop in blood pressure.
Electrocardiogram
Important in the diagnosis of atrial tachycardia.
It can determine the type of atrial tachycardia.
The electrocardiogram of atrial tachycardia shows an increased atrial rate, altered P-wave morphology, some P-waves that do not travel downward, and an irregular ventricular rate.
Ambulatory electrocardiogram
An ambulatory electrocardiogram provides information about changes in the patient’s cardiac activity over a 24-hour period.
It is important in the diagnosis of patients with transient atrial tachycardia.
Laboratory tests
Blood biochemistry
Electrolytes: to see if electrolyte disturbances are present and to assist in finding the cause of atrial tachycardia.
Serum troponin, cardiac enzymology: to understand myocardial metabolism, used to assess the condition and determine the cause of supraventricular tachycardia, such as acute myocardial infarction and acute myocarditis patients are often elevated.
Blood B-type natriuretic peptide (BNP) or N-terminal B-type natriuretic peptide proteins (NT-ProBNP): used to assess cardiac function and to determine the presence of heart failure.
Serum digitalis levels should be tested in patients with a history of digitalis use.
Blood gas analysis
Dynamic arterial blood gas analysis can be used to find out whether there are metabolic disorders such as hypoxia, acid-base imbalance and other factors, which is helpful in finding the cause of the disease.
Thyroid Function
Thyroid function can be understood to assess the presence of hyperthyroidism and other etiologic factors.
Imaging
Echocardiography
It is mainly used to understand the structural condition of the heart and to determine the presence of structural cardiac lesions.
Chest X-ray or Chest CT
To find out if there is lung disease, mainly used to find the cause of the disease.
Cardiac electrophysiology
An electrophysiologic examination of the heart can help to understand the cause of atrial tachycardia.
It can accurately record the electrical activity of the patient’s atria, look for ectopic rhythms in the patient’s atria, identify other atrial arrhythmias, and assess the patient’s prognosis.
Coronary Angiography
Coronary angiography is important for the diagnosis of atrial tachycardia due to coronary artery disease.
Lung function
It is important for the diagnosis of atrial tachycardia caused by chronic obstructive pulmonary disease, bronchial asthma and other lung diseases.
Diagnostic Criteria
Atrial tachycardia is diagnosed primarily by the characteristic ECG findings.
Focal atrial tachycardia
The atrial rate is mostly between 150 and 200 beats/minute.
The P-wave morphology is different from that of sinus P-wave.
Sometimes second-degree type I or type II atrioventricular block is present, and 2:1 atrioventricular conduction is common, but does not affect the tachycardia.
Stimulation of the vagus nerve only aggravates the patient’s atrioventricular block and does not terminate the tachycardia.
The patient’s heart rate accelerates gradually from the onset of the episode.
Polygenic atrial tachycardia
The atrial rate is mostly between 100 and 130 beats/min.
P-wave morphology varies, PR intervals vary, and there are mostly three or more P-waves that are different from sinus P-waves.
Some of the P waves do not travel down to the ventricles, and the ventricular rate is irregular.
Differential Diagnosis
Atrial tachycardia needs to be differentiated from other atrial arrhythmias:
Atrial preterm contraction
Similarities: Both may present with palpitations, chest tightness, and weakness. P-waves different from sinus P-waves are seen on the electrocardiogram.
Differences:
The ECG of atrial pre-systole shows early onset of P waves, PR interval >120 ms, supraventricular QRS wave trains, and conduction interruption or slow conduction.
The electrocardiogram of atrial tachycardia shows an increased atrial rate, failure of some P waves to transmit downward, and an irregular ventricular rate.
Atrial flutter
Similarities: both may present with palpitations, chest tightness, and weakness.
Differences:
The electrocardiogram of atrial flutter shows that the atrial rate increases to 250~350 beats/min, sinus P wave disappears, flutter wave (F wave) with the same amplitude and spacing and regularity appears, and the equipotential line between F waves disappears.
The electrocardiogram of atrial tachycardia shows that the atrial rate is mostly between 100 and 200 beats/min, the P-wave morphology is different from that of sinus P-wave, and the equipotential lines between the P-waves still exist.
Atrial fibrillation
Similarities: Both may present with palpitations, chest tightness, and fatigue.
Differences:
The electrogram of atrial fibrillation shows that the atrial rate increases to 350-600 beats/minute, sinus P wave disappears, f wave with variable amplitude and spacing and irregularity appears, and the ventricular rate is extremely irregular.
Combined with the patient may appear the first heart sound strength is not equal, the heart rhythm is absolutely irregular, pulse shortness and other signs, can be distinguished from atrial tachycardia.
Treatment
The purpose of treatment: timely removal of the causes or triggers, control of the ventricular rate and reversal of sinus rhythm, to maintain hemodynamic stability of the patient.
Principles of treatment: The treatment of atrial tachycardia depends on the rapidity of the ventricular rate and the hemodynamic situation of the patient, and different therapeutic strategies should be chosen according to the patient’s condition.
In patients with a less rapid ventricular rate and no severe hemodynamic disturbances, most patients do not require urgent treatment.
Patients with a ventricular rate of more than 140 beats/minute and severe hemodynamic disturbances due to digitalis intoxication should be treated as emergencies.
Emergency Management
Stimulation of the vagus nerve
Valsava maneuvers (i.e., asking the patient to inhale deeply, then hold his breath and exhale forcefully for 10-30 s), submerging the face in ice water, diving for breath-holding maneuvers, or stimulating the patient’s pharynx to induce nausea are all methods that are occasionally effective.
Occasionally effective, has been rarely used.
Medication
Adenosine.
Terminates most focal atrial tachycardias.
May cause sinus bradycardia, atrioventricular block, facial flushing, and other adverse effects.
It is contraindicated in the elderly and those with sick sinus node syndrome.
Beta-blockers or
may terminate a small proportion of atrial tachycardia.
Commonly used drugs include metoprolol, bisoprolol, and diltiazem.
Use with caution in the presence of severe cardiac insufficiency.
Ⅰa, Ⅰc or Ⅲ antiarrhythmic drugs
They can terminate part of atrial tachycardia.
Commonly used drugs are class Ia (such as quinidine, procainamide, etc.), class Ic (such as propafenone) or class III (such as amiodarone, sotalol, etc.).
Amiodarone is preferred for those with heart failure manifestations, and attention should be paid to detecting changes in the patient’s blood pressure, electrocardiogram, liver and renal function and other indexes during the administration of the drug.
Esophageal atrial pacing
Indications
Esophageal atrial pacing can be considered for those who have failed drug resuscitation or have contraindications to the use of drugs.
Contraindications
Acute upper respiratory tract infection.
Aortic aneurysm.
Severe hypertension or other intolerable conditions.
Direct Current Pacing
Indications
Severe angina, hypotension, acute heart failure.
In cases where pharmacologic therapy is ineffective.
Contraindications
Arrhythmias due to digitalis intoxication.
Electrolyte disorders pathological sinus node syndrome.
Cardiac enlargement, atrial fibrillation with history of embolism or intra-atrial thrombus.
Chronic phase treatment
General treatment
Actively treat the primary disease and correct electrolyte disorders.
Medication
Non-dihydropyridine calcium channel blockers
Can control the ventricular rate.
Commonly used drugs include diltiazem, verapamil and so on.
Caution: contraindicated in the presence of severe cardiac insufficiency.
β-blockers
Can slow down the ventricular rate and reduce myocardial oxygen consumption.
Commonly used drugs include metoprolol, bisoprolol and so on.
Caution: Use with caution in the presence of severe cardiac insufficiency.
Catheter radiofrequency ablation
Indications
Persistent atrial tachycardia, especially atrial tachycardia without rest.
Contraindication
Presence of left atrial thrombus.
Coagulation disorders.
Presence of infection at the surgical site.
Presence of other conditions that do not tolerate the procedure [9-10].
Prognosis
Cure
The prognosis of atrial tachycardia is related to the patient’s condition.
Some patients have the possibility of self-healing after removal of the cause and triggers.
Most patients without organic cardiac lesions and with normal cardiac function can be cured after active treatment and have a good prognosis.
Patients with organic cardiac lesions, cardiac insufficiency, or underlying lung disease are difficult to cure and are prone to recurrent or persistent episodes, which further aggravate the structural cardiac lesions and cardiac insufficiency, and have a poorer prognosis.
Harmfulness
Recurrent or persistent attacks can lead to cardiac insufficiency and symptoms such as chest tightness and shortness of breath after activity, which reduces the patient’s activity tolerance and affects daily life and work.
Daily
Daily management
Dietary management
Low-salt and low-fat diet: daily sodium intake should be no more than 5g, oil intake should be no more than 40g, and high-fat and high-cholesterol foods such as animal oil, fatty meat, animal offal and fried food should be avoided as much as possible.
It is advisable to eat fresh fruits and vegetables rich in vitamins and fiber.
Avoid strong tea, coffee and other stimulating drinks.
Quit smoking and drinking
Smoking should be strictly quit, while avoiding passive smoking and alcoholism.
Daily care
Regular work and rest, avoid overwork and late nights.
Maintain a happy mood and avoid violent mood swings.
Exercise moderately after the condition is stabilized.
Patients who need to take long-term medication should remember to follow the doctor’s instructions to take medication regularly, do not reduce or stop the medication on your own.
Follow-up
Patients with atrial tachycardia need to be followed up regularly so that the doctor can assess the changes in their condition and make timely adjustments to the treatment plan.
The time of follow-up should be decided by the doctor according to the patient’s specific condition.
The items that need to be reviewed include electrocardiogram, cardiac ultrasound, BNP, cardiac enzymes, etc. Patients who have been taking oral medication for a long period of time should pay attention to monitoring the changes of electrolytes, liver and kidney functions, and other indicators.
Prevention
There are no effective preventive measures for atrial tachycardia, but the following measures can reduce the incidence of the disease.
Avoid overwork and late nights.
Avoid alcohol abuse.
Maintain a good state of mind and avoid excessive mood swings.
Have regular medical checkups and seek medical attention if there is any abnormality in the ECG.
After suffering from coronary heart disease, cardiomyopathy, chronic obstructive pulmonary disease, pulmonary heart disease, hyperthyroidism and other diseases, we should standardize the treatment as early as possible, strengthen the daily management, control the condition and slow down the progress of the disease.