PSVT is a type of irregular heart rhythm, also called an arrhythmia. The rhythm is fast and can start and stop abruptly. This type of arrhythmia does not usually cause harm to an individual, however, in some cases, it may require treatment.

Understanding the potential causes of this condition and the associated symptoms can enable you to identify and seek appropriate medical advice. 

Understanding normal heart rhythm vs PSVT

The heart is split into four chambers. The top two chambers are called atria and the bottom chambers are called ventricles. A heartbeat is initiated by a cluster of specialised cells called the the sinoatrial (SA) node.

This is located in the upper part of the right atria of the heart and are also referred to as pacemaker cells. A nerve impulse is generated by these packmaker cells causing the atria to contract. As the atria contract, they push blood through valves into the ventricles.

The impulse from the SA node flows to the atrioventricular (AV) node, which is located between the atria and ventricles. which causes the ventricles to contract. This in turn causes the blood that is in the ventricles to be moved out of the heart and into circulation. Each pump of the heart pushes the blood further around the body until it arrives back to the heart. This process is continually repeated and produces your heartbeat.

A normal heartbeat is between 60-100 beats per minute (bpm), however, can vary between individuals. In PSVT this process is disrupted due to dysfunction at the SA node and is characterised by heart rates greater than 100bpm. Paroxysmal means that it occurs intermittently.

Types of PSVT

PSVT can be classified depending on where they originate from within the heart and if they have any regularity to their rhythm or not.¹ Some of the classifications include:

• Atrioventricular nodal re-entrant tachycardia
• Sinoatrial node re-entrant tachycardia
• Multifocal Atrial tachycardia

Atrioventricular nodal re-entrant tachycardia (AVNRT)

This is the most common type of PSVT and accounts for approximately 60% of patients undergoing electrophysiology assessment.² This arrhythmia occurs when an extra circuit is formed close to the AV node in the impulse pathway. This causes a re-entrant circuit which can cause the heartbeat to come too early. As a result, the beats per minute rate can increase from 140bpm to over 200bpm.³

Sinoatrial node re-entrant tachycardia

This type of PSVT is less common with rates for patients presenting with a PSVT between 2-17%.⁴ This is caused by the formation of a re-entrant circuit close to or within the SA node. The heart rate can be between 100-150bpm. This type is more poorly understood due to its rarity and difficulties in diagnosis.

Multifocal Atrial tachycardia (MAT)

This type of arrhythmia is more common in elderly people suffering from chronic diseases such as Chronic Obstructive Pulmonary Disease (COPD).⁵ MAT is less common than AVNRT. It is unproven how MAT develops, however it is suggested there could be multiple extra circuits located in the atria, causing re-entrance of the impulse triggered in the SA node. Another theory suggests that complications due to chronic conditions, cause the muscle cells within the atria to spontaneously trigger an impulse in the conduction pathway.⁵

Common triggers and risk factors

There are several potential triggers and risk factors that could contribute to the development of PSVT.¹ Certain medications can cause arrhythmias:

• Salbutamol
• Hydralazine

Recreational drugs can also cause PSVT including:

• Cocaine
• Ecstasy
• Amphetamines
• Alcohol

Several medical conditions can predispose you to develop PSVT

• Cardiomyopathy
• Myocardial Infarction (heart attack)
• Pulmonary embolism
• Pneumonia
• High-stress levels and high anxiety

Symptoms of PSVT

PSVT usually starts and stops abruptly, so symptoms may come on suddenly and be short-lived. This can be alarming and frightening when experienced. The symptoms can range from mild to severe and vary from person to person.

Symptoms may include:

•  A fast, regular heartbeat 
• Fluttering or pounding in your chest and an awareness of your heartbeat, also known as palpitations
• Lightheadedness leading to fainting
• Anxiety and panic
• Fatigue
• Nausea or vomiting
• Chest pain
• Generally feeling unwell

Recognition and diagnosis

Clinical presentation and accurate history are vital in the correct diagnosis of PSVT. It is important to understand what may have triggered the episode and the nature of how it progressed including symptoms experienced.

Your healthcare professional will examine your pulse and listen to your heart A procedure called an electrocardiograph (ECG) will be performed to aid diagnosis. This test is performed at the hospital or clinic and involves placing electrode stickers across your chest and limbs to produce a reading of the electrical impulses generated within the heart.

If the arrhythmia has stopped by the time you undergo the test, you may be asked to wear an at-home ECG for 24 hours called a Holter monitor. This gives a longer duration of the hearts electrical activity, rate, and rhythm. 

Management and treatment

In most cases, PSVT is not harmful and resolves without intervention. Treatment is dependent on the severity of symptoms and if the heart rate begins to compromise the body’s ability to maintain blood pressure and oxygenation.

Acute management

There are numerous management and treatment options for PSVT. In the acute period, vagal manoeuvres can be performed by a healthcare professional to stimulate the vagus nerve as it runs through the carotid sinus in the neck. The vagus nerve plays a role in regulating the heartbeat and rhythm. Stimulation with techniques such as carotid sinus massage can help the heart to slow down.

Another manoeuvre is the Valsalva technique. This technique is performed by blowing air into a syringe until the plunger moves. Success rates vary, however, one study found that lying flat with legs elevated during the action improved the outcomes of this.⁶

Please note - Do not attempt of these manoeuvers without the guidance of a medical professional. If experiencing any concerning signs, please seek medical advice immediately. 

For individuals that have complications from PSVT such as a compromised blood pressure, it may be necessary to perform a cardioversion.⁷ Cardioversion is the administration of electrical impulses to shock the heart back into a normal rhythm.

The use of medications can also be used in acute management. These medications have properties that can help the heart revert to a normal rhythm by slowing the actions of the cells producing the impulses and triggering the conduction pathways.

Long-term management

For individuals with recurrent episodes causing difficulties with quality of life, there are options for medical and surgical management of PSVT.

Medical management includes the use of medications such as beta-blockers or calcium channel blockers. These medications can help to slow the heart rate by relaxing the muscles of the heart and associated vessels. This in turn can reduce the workload of the heart and when taken regularly can aid regulation of the heart’s rhythm.

Surgical management is in the form of a procedure called catheter ablation. This procedure can be performed under local anaesthesia and as a day case. A thin tube called a catheter is placed into a major vein in the leg. It is extended along the vein and up towards the heart the catheter can detect the electrical impulses in the heart and can identify where the irregularity is located. The location of the cluster of cells causing the “short circuits” are pinpointed and destroyed using either heat (radiofrequency) or cold therapy (cryotherapy).

Lifestyle modification

Making modifications to your lifestyle can have an impact on reducing episodes of PSVT. Positive lifestyle changes you can make to reduce the occurrences of PSVT include:

• Stopping smoking
• Reducing alcohol intake
• Avoiding caffeine products
• Do not use recreational substances such as cocaine and ecstasy
• Exercising regularly
• Managing stress

Impact of PSVT on Health

Potential complications

The impact of experiencing PSVT can vary between individuals. In the majority of cases, the arrhythmia self-terminates and does not require intervention. However, in some individuals, it can require intervention and could lead to complications. When the heart is beating over 100bpm for a prolonged period of time, its ability to pump blood around the body can be compromised putting strain on the heart muscles. Over long periods of time, this could lead to the development of heart failure.

Effect on quality of life

Prolonged and recurrent episodes of PSVT can have significant impacts on an individual’s quality of life. Due to the nature of the arrhythmia initiating abruptly, it can cause panic and anxiety when it arises, which can have a detrimental effect on everyday life. It may leave an individual feeling unwell when it occurs and often without any warning of its onset. Individuals may avoid engaging in certain activities due to fear or avoid social events due to debilitating symptoms.

Early recognition and management of the condition is important to reduce the impact on quality of life. By understanding any potential triggers, an individual can have an awareness of when it may occur and take steps to prevent these. An understanding of what is happening and techniques to manage symptoms, but also when to seek medical help is important.

Summary

For most people PSVT has minimal impact on health and quality of life. Most cases do not require treatment and occurrences can be prevented through lifestyle modifications. However, for a small proportion of people treatment may be required through either medical or surgical management. There is sometimes a risk of complications in some individuals. However, early recognition and management can lead to positive outcomes.