What is Atrial Tachycardia?
Atrial tachycardia is a type of heart rhythm problem where the heartbeat originates from within the upper chambers of the heart, also known as the atria. It can be caused by one or a mix of factors which lead to irregular heartbeats – these can be automatic, triggered, or circulatory issues. Sometimes, why it happens remains unknown. When it comes to diagnosing atrial tachycardia, the features can sometimes overlap, especially if there’s a small resurgent circuit, which is referred to as micro-re-entry. This condition can broadly be categorized into two types: macroreentrant or focal.
Macroreentrant atrial tachycardia, best exemplified by atrial flutter, originates from the right atrium. The electrical impulses travel within a circuit bounded by the tricuspid valve (at the front) and the crista terminalis and Eustachian ridge (at the back). The electrical activity can move in either a clockwise or anti-clockwise direction within this circuit.
Atrial flutter is a complex type of irregular heartbeat, which is managed differently than focal atrial tachycardias. Therefore, in this context, we’ll focus more on the focal type of atrial tachycardia (FAT).
What Causes Atrial Tachycardia?
Atrial tachycardia, a kind of fast heart rate, often happens in people who have heart diseases, whether or not they also have heart failure. This can also occur in those with ischemic coronary artery disease, which is a condition where the heart’s arteries become narrow or blocked. On the other hand, focal atrial tachycardia – another type of fast heart rate – can occur in healthy people without any heart diseases.
There are many possible other causes or triggers of these types of fast heart rates, including:
- Lack of oxygen in the body (hypoxia)
- Diseases of the lungs
- Ischemic heart disease (aforementioned)
- Stimulants such as cocaine, caffeine, chocolate, or the herb ephedra
- Alcohol
- Disturbances in the body’s metabolism
- Too much digoxin (a heart medication) in the body (digoxin toxicity)
- A high level of activity in the sympathetic nervous system controlling “flight or fight” response
Risk Factors and Frequency for Atrial Tachycardia
The exact number of people affected by focal atrial tachycardia is unclear. However, a study conducted in Europe revealed that among young men applying for pilot licenses, 0.34% experienced symptoms of atrial tachycardia. Another 0.46% had noticeable symptoms of atrial tachycardia. Moreover, another study found that between 10 to 15% of patients seeking treatment for supraventricular tachycardia, a similar heart rhythm disorder, actually had atrial tachycardia.
Signs and Symptoms of Atrial Tachycardia
When talking about patients, it’s important to consider their medical background which includes their current medications, previous medical and surgical treatments, and lifestyle habits like smoking, drinking, caffeine intake, and use of substances. Certain medical conditions such as chronic lung disease or pulmonary hypertension, may make patients more likely to experience atrial tachycardia, a type of heart condition. Similarly, chronic alcohol consumption or withdrawal can also increase the risk of this heart condition. If the patient had heart surgery in the past, it could also lead to atrial tachycardia.
Atrial tachycardia may show up during heart monitoring of patients who otherwise seem fine, or even while they’re sleeping. However, symptoms may occur if the heart condition is due to an underlying health issue.
People with atrial tachycardia may experience various symptoms:
- Feeling of rapid heartbeat
- Light-headedness
- Chest pain or pressure
- Shortness of breath
- An irregular heart rhythm
The severity of these symptoms depends on how fast the heart is beating and the overall heart health of the patient. In some cases, symptoms can come and go, while for others they may be more persistent. Certain triggers like caffeine consumption, stress, and exercise can also spark these symptoms. An important thing to remember is that atrial tachycardia cannot be stopped using adenosine, a medicine often used to control irregular heartbeats.
When atrial tachycardia continues for a long time, it can affect the heart muscle and lead to cardiomyopathy. This condition could result in symptoms like difficulty breathing after exerting effort, increased swelling in the lower legs, and chest pain. Even though the general course of atrial tachycardia is usually not severe, it may increase the risk of sudden cardiac death.
During a physical evaluation, doctors might detect a heart rate above 100 BPM indicative of regular or irregular atrial tachycardia. If the tachycardia includes a variable block, there might be variance in the heart sounds with every heartbeat. Also, there might be excessive A waves observed during the examination of the jugular venous pulse.
Testing for Atrial Tachycardia
An EKG, or electrocardiogram, can be helpful in diagnosing a type of heart issue called focal atrial tachycardia. Features seen on an EKG can also suggest where exactly this irregular heartbeat is coming from. Here are some details about the features doctors might look for on an EKG:
– The atrial rate (one part of your heartbeat) is between 100 to 250 BPM (beats per minute).
– The way your ventricles (the lower chambers of your heart) conduct electricity can vary.
– The rhythm might be uneven or highly irregular if there’s variable AV block, a condition where the signal from the top chambers of your heart to the bottom is blocked intermittently.
– If the block is consistent, like 1 to 1, 2 to 1, or 4 to 1, the rhythm becomes more regular.
– The P wave (one part of the heart’s electrical signal) has a specific shape.
– All P waves look similar to each other but they might be inverted (flipped in direction).
– The look of the P wave will be different from a regular sinus P wave (the one you’d see in a normal heartbeat).
– Your heart rhythm could show either long RP (the time between the start of one part of your heartbeat and the start of the next) or short PR intervals (the time between two different parts of your heartbeat).
– The rhythm could start and stop quickly, or it may continue for a period.
– It might start slow and then “rev up” in speed.
– It might also go fast and then “cool down” and slow down when it stops.
Treatment Options for Atrial Tachycardia
The first step in managing atrial tachycardia, a condition where the heart beats abnormally fast, is to deal with what might be causing it. This could mean treating any current sickness, stopping the use of stimulants, reducing stress, managing any digoxin toxicity, or handling chronic diseases properly.
To control the heart rate, medications called beta blockers or calcium channel blockers can be used. If the fast heart rhythm continues and is causing the patient discomfort or other symptoms, certain types of antiarrhythmics, which are drugs used to correct heart rhythm problems, may be beneficial.
However, when deciding to use these antiarrhythmic medications, it’s important to weigh the potential benefits against possible risks, particularly for patients with ischemic or structural heart disease.
If medication isn’t effective, a procedure known as catheter ablation may be an option. This involves using heat or cold energy to create tiny scars in the heart, which can help block abnormal electrical signals leading to the fast heart rhythm.
Bear in mind that many types of atrial tachycardia are driven by an increased automatic response in the heart. Therefore, just using electrical cardioversion alone, which is a medical procedure that restores a normal heart rhythm, without the above-mentioned medical therapy could likely lead to the return of the fast heart rhythm.
What else can Atrial Tachycardia be?
Focal atrial tachycardia may be mistaken for other similar conditions that also present with continuous, narrow complex fast heart rates. It becomes even more difficult to identify when there are some changes during the start (“warm-up”) and end (“warm-down”) periods. Furthermore, atrial tachycardia usually presents narrow complex QRS (a pattern seen in an electrocardiogram (ECG) reading) unless there’s a disrupted connection to the ventricles or if there is a bundle branch block.
Since the treatment for focal atrial tachycardia differs from other regular, narrow complex fast heart rates, it’s critical to correctly identify it from other similar conditions. Here’s a list of these conditions along with their distinguishing features:
– Similar conditions with regular, narrow complex heart rates
1. Sinus tachycardia: Identified by a P wave with a superior axis
2. Atrial flutter: Characterised by a biphasic, sawtooth-like F wave.
3. AVNRT: Different forms can either have a short or long time interval between the P wave and R wave (RP interval).
4. AVRT: Identified by a negative P wave before QRS complex, and specific findings in the EKG.
5. Atrial tachycardia (Focal)/Junctional tachycardia: P wave might be missing or inverted.
– Similar conditions with irregular, narrow complex heart rates
1. Atrial fibrillation: Presents with an irregular rhythm.
2. Atrial flutter or atrial tachycardia with variable AV block: Irregular rhythm due to variable block.
3. Multifocal atrial tachycardia: P wave morphology shows three or more distinct shapes.
What to expect with Atrial Tachycardia
Focal atrial tachycardia, a type of heart rhythm disorder, is generally not dangerous. However, the overall outcome depends on the specific factors causing this rhythm issue. If this disorder continues for a long time, it can lead to heart muscle diseases known as tachycardia-induced cardiomyopathies.
If doctors are concerned about patients having a high amount of rapid irregular heart rhythms, they should be monitored outside the hospital with tools like a Holter monitor or remote/mobile telemetry. If necessary, their medication can also be adjusted to manage the condition.
Preventing Atrial Tachycardia
The factors that can increase your risk of experiencing an irregular heartbeat, or arrhythmia, are much the same as those for heart disease. Living a heart-healthy lifestyle, which includes eating a balanced diet, exercising regularly, and avoiding tobacco products, is key to preventing arrhythmias. Additionally, steering clear of stimulants such as caffeinated products can help reduce the occurrence of a rapid heartbeat or focal atrial tachycardia.
People with atrial tachycardia may encounter symptoms like heart palpitations, feeling light-headed, and developing a condition called pre-syncope, which can understandably lead to feelings of anxiety. It’s crucial to remind patients that even though atrial tachycardia can be an uncomfortable experience, it’s not a life-threatening heartbeat irregularity.
