What Is Sinus Arrhythmia?

Have you ever heard the term ‘sinus arrhythmia’ and thought it was a life-threatening disease? Well, it is not. In fact, it is quite the contrary – it is a sign that your heart works properly. 

Sinus arrhythmia is an abnormal heart rhythm which occurs because your heart rate (number of beats per minute) increases when you inhale and decreases when you exhale. If your heart does not experience this phenomenon to some degree, it might be a sign of disturbed cardiovascular health. 

This article will further explain sinus arrhythmia – the different types that exist, its causes, symptoms, management, and possible complications; and provide some helpful tips. So, keep scrolling if you want to know more.

The cardiac system

Anatomy of the heart

The heart is the primary organ in the cardiovascular system that, through its pumping action, produces and controls blood flow and blood pressure and governs the rhythm and pace of the heartbeat. Here is a diagram to help you understand its anatomy, where the heartbeat starts and how it propagates:

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The cardiac conduction system

The cardiac conduction system of the heart is analogous to the electrical wiring controlling the timing of a car’s engine. It generates and controls the electrical signals that cause the heart to beat, synchronising the contraction of its four chambers and thereby controlling the movement of blood between them and the heart rate:

• The sinoatrial (SA) or sinus node generates electrical signals, which then travel to the atrioventricular (AV) node.
• The AV node acts as a gatekeeper that slows down the signal so that coordination with the atrial chambers (the right and left top parts of the heart that receive blood from the body and lungs, respectively) permits a brief period for the blood to be passed to the larger ventricular chambers (the right and left bottom parts of the heart that pump blood out to the lungs and body respectively)
• The signal continues from the AV node through some special fibres - the bundle of His and Purkinje fibres, which stimulate the ventricles, making them contract in an organised fashion, and consequently pump the blood under pressure into the lungs and body’s circulation.

The heart's expansions and contractions produce the heartbeat, and they are responsible for the flow of blood around the body. In addition, the cardiac conduction system ensures that the heart rate speeds up when we exercise (necessary because the muscles require greater blood flow) and slows down when we rest.¹

Sinus rhythm

Normal sinus rhythm

The normal sinus rhythm is the regular beating of the heart, which starts at the sinus node and follows the path explained above. Usually, in a resting state in adults, the heart rate is between 60 to 100 beats per minute. However, this could vary depending on the person.²

The SA node's role in sinus rhythm

The sinus node continually generates electrical currents, which are responsible for setting the rhythm and rate of the cardiac cycle of the heart. This is why the SA node is known as the pacemaker of the heart. Moreover, when the the body needs more oxygen, for example during exercise, the SA node will help increase the heart rate, whereas during rest or sleep it will decrease it.³

Sinus arrhythmia

Is sinus arrhythmia a heart problem?

Respiratory sinus arrhythmia is a common natural variation in the normal cardiac sinus rhythm. Unlike the normal sinus rhythm, the time between heartbeats, in this instance, is irregular, meaning, specifically, that it is shorter when we breathe in and longer when we breathe out. Sinus arrhythmia is usually an indicator of good cardiovascular health. However, there are other types of sinus arrhythmia.

Types of sinus arrhythmia

There are two main types of sinus arrhythmia:

Respiratory sinus arrhythmia

• This is the common type
• It is synchronised with our breathing, meaning that the heart rate is faster during inspiration and slower during expiration.
• Breathing stimulates the action of the vagus nerve on altering the pace of the sinoatrial (SA) or sinus node.⁴

Non-respiratory sinus arrhythmia

• In contrast to respiratory sinus arrhythmia, this type is not linked to breathing.
• It can be a sign of thyroid problems, cardiovascular issues, digitoxin ingestion, and neck or head trauma^5,6

Do all people have sinus arrhythmia?

Respiratory sinus arrhythmia is commonly seen in healthy children and young adults. Its occurrence tends to decrease with age, however there is not specific age when this occurs.^{4, 7} There is research that indicates that fewer older individuals (over 50) present with sinus arrhythmia compared to a younger group (under 30).⁸  It is suggested that this is caused by the body of older individuals being unable to perform its reflex physiological responses with the same sensitivity as during youth.² 

Non-respiratory sinus arrhythmia is experienced by adults with an existing cardiovascular disease following digitoxin poisoning or head or neck trauma. ^4,5

Causes of sinus arrhythmia

Respiratory sinus arrhythmia

• Changes in respiration ^{4, 6}
• Stimulation of the vagus nerve by sympathetic stimulation (increases heart rate in response to anxiety, excitation, exercise, giving you the sensation of palpitations) or parasympathetic stimulation (lowers heart rate in response to rest and sleep)^{2 6}

Non-respiratory sinus arrhythmia

Several causes can result in non-respiratory sinus arrhythmia, including:

• Heart disease
• Sick sinus disorder
• Head or neck injury
• Increased intracranial pressure
• Medications that lower blood pressure, such as beta-blockers and calcium channel blockers 
• Medications that treat arrhythmias and other heart problems, such as Digoxin ^2,4,6 

Symptoms and diagnosis

Normally, there are no symptoms associated with respiratory sinus arrhythmia. In regards to non-respiratory arrhythmia, the physiological signs are associated with the underlying disorder the person suffers from. Some symptoms that might be present are:^2,4,6

• Tachycardia (heart palpitations)
• Bradycardia (reduced heart rate)
• Lightheadedness 
• Fatigue
• Shortness of breath
• Swelling of legs 
• Weakness, numbness and pain in limbs
• Disturbed digestion

Diagnostic methods

Electrocardiogram (ECG)

The most common method that identifies sinus arrhythmia is the electrocardiogram (ECG). In the case of respiratory sinus arrhythmia, the information that your physician should observe from the ECG is:^2,4

• The interval between heartbeats, also known as the P-P interval, varies by more than 120 milliseconds (0.0120 seconds)
• Also, the P-P interval variation should correspond with breathing, meaning that it will be shorter when breathing in and longer when breathing out.
• A QRS complex should follow the P waves^2,4

You should keep a copy of your ECG in case of need in the future.

Careful assessment via an electrocardiogram should be able to rule out other serious causes of arrhythmia, such as atrial fibrillation, flutter, or multifocal atrial tachycardia.

Holter monitor

If you experience unexplained palpitations along with some other symptoms like dizziness, and your medical history and ECG cannot determine the cause, a Holter monitor may be used to determine a diagnosis of arrhythmia or other possible issues. This is a small portable ECG device that you need to wear for 24 to 48 hours.⁹

Echocardiogram

Another way to diagnose types of arrhythmia is through an echocardiogram. This is a heart ultrasound which assesses the structure of your heart, as well as its function.¹⁰ 

Management and treatment

Sinus arrhythmia does not require treatment. In the case of non-respiratory arrhythmia, the treatment prescribed will target the underlying cause.

Prognosis and complications

The prognosis for sinus arrhythmia

The presence of sinus arrhythmia is an indicator of a healthy heart, especially in young individuals. On the contrary, its absence or dysregulation might be a sign of health conditions, including diabetes mellitus or cardiovascular disease.^2,4,11

Complications associated with sinus arrhythmia

There are rarely any complications observed in this condition. 

However, there are complications associated with other types of arrhythmia resulting from more severe conditions, such as :

• Stroke
• Heart failure 
• Cardiac arrest
• Atrial fibrillation
• Death

Can you live a full life with sinus arrhythmia?

If you are a healthy person with no underlying chronic diseases, then it's likely you have respiratory sinus arrhythmia, which is actually a sign of good health, so you can certainly live a normal life. There is a good chance that you might not even have been aware that you have this condition until it is detected incidentally during an ECG examination for some other reason. 

Some research suggests that stress has an influence on respiratory sinus arrhythmia. It tends to decrease the response that produces the changes in heart rate between inhalation and exhalation.¹³ However, further research is needed to understand more fully the connection between anxiety and stress and respiratory sinus arrhythmia.

Concerning heart health, more generally, exercising will be good for you as it will keep your body active and healthy. However, if you experience irregular heartbeat due to another cardiovascular condition, you should consult a specialist to establish which type of exercise is the most appropriate for you. For instance, if you are diagnosed with serious heart problems, a more relaxed type of exercise such as yoga might be more suitable for you.

In addition, maintaining a balanced diet is always important. However, if you have a severe arrhythmia due to a more serious cause or have a risk factor which could result in other kinds of arrhythmia, then, according to some cardiovascular research, you should avoid grapefruit juice and energy drinks.¹²

Finally, you do not need constant medical check-ups for this condition. 

However, more generally, and in relation to other types of arrhythmias, if you start experiencing palpitations that will not go away or other symptoms, you should consult a health professional.

Summary

Sinus arrhythmia is usually the result of a natural variation of the heartbeat caused by the process of breathing that indicates good cardiovascular health, especially in young people. The absence of this condition could possibly be a sign of health problems. Because sinus arrhythmia in adults tends to decrease with age, its continued presence might, therefore, be an indicator of a heart issue with associated non-respiratory sinus arrhythmia, which, contrary to the normal respiratory type, is not merely related to breathing. 

Sinus arrhythmia rarely produces any symptoms and it does not need treatment unless it is to target any underlying disease that causes it. In conclusion, this condition is usually completely normal. However, if you have any concerns, you should consult a medical expert. 

FAQ’s

Does sinus arrhythmia cause chest pain?

No, sinus arrhythmia does not usually produce any type of symptom. Therefore, if you are experiencing chest pain, you should consult a cardiologist.

Does sinus arrhythmia ever go away?

Usually, the presence of sinus arrhythmia decreases with age. However, during youth, you should not want it to go away, as it indicates that you are healthy.

Can a sinus arrhythmia be unrelated to breathing?

Yes, this is known as non-respiratory sinus arrhythmia, and it tends to be a sign of underlying health problems. 

How do you fix sinus arrhythmia?

No treatment exists or is required for this condition. However, if you have non-respiratory sinus arrhythmia as a consequence of an illness, your doctor will prescribe you medications that target the specific disease.