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Heart Health

Arrhythmias (Heart Rhythm Disorders)

Arrhythmias (Heart Rhythm Disorders)

A heart arrhythmia is a generic term for an abnormal heart rhythm. 

Whether an arrhythmia is insignificant or life-threatening depends on its:
  • Duration
  • Rate
  • Degree of regularity
  • Its effect on blood flow and blood pressure

There are four main types of arrhythmia: (1) Premature (extra) beats; (2) Supraventricular arrhythmias; (3) Ventricular arrhythmias; (4) Bradyarrhythmias.

1. Premature (Extra) Beats

This is the most common type of arrhythmia. It is mostly harmless and may not cause any symptoms. In most cases, premature beats require no treatment. 

However, certain conditions or factors may also cause this such as:

  • Structural heart diseases
  • Psychological stress
  • Caffeine or alcohol 
  • Sympathomimetic drugs

2. Supraventricular Arrhythmias

These are fast heart rhythms (tachycardia) that begin above the ventricles - in the atria, the atrioventricular node, or the atrioventricular junction. 

Some types of supraventricular arrhythmias include: atrial fibrillation (AF); atrial flutter; paroxysmal supraventricular tachycardia (PSVT); and Wolff-Parkinson-White (WPW) syndrome.

2.1. Atrial Fibrillation (AF)

AF refers to very fast and irregular contraction of the atria causing disorganised, rapid and irregular rhythm. This allows blood to pool in the left atrium and form clots that may embolise to the brain or elsewhere. It is the most common type of serious arrhythmia, which may cause stroke or heart failure.

2.2. Atrial Flutter

Instead of fast and irregular rhythm in AF, atrial flutters are fast and regular (organised, macro-reentrant atrial arrhythmia). It has similar symptoms and complications as AF. However, it is less common than AF.

2.3. Paroxysmal Supraventricular Tachycardia (PSVT)

PSVT is a very fast heart rate that begins and ends suddenly. They are usually due to reentry ("short-circuits") within the heart. This type of arrhythmia is usually not life-threatening, but can cause troublesome symptoms and in rare cases, result in heart failure if intractable. 

2.4. Wolff-Parkinson-White (WPW)

This is a type of PSVT, where there is an (inborn) extra electrical (accessory) pathway from the atria to the ventricles. It can result in fast heart rates due to reentry. This condition can sometimes be life-threatening depending on the characteristics of the accessory pathway.

3. Ventricular Arrhythmias

These begin in the ventricles and can be very dangerous, usually requiring immediate medical attention. Ventricular arrhythmias include ventricular tachycardia and ventricular fibrillation.

Coronary artery disease (CAD),  heart attack (myocardial infarction) and weakened heart muscle can cause this.

3.1. Ventricular Tachycardia (VT)

This is characterised as fast, regular beating of the ventricles that may last only for a few seconds or much longer. Ventricular tachycardia that lasts for more than a few seconds can degenerate into more dangerous arrhythmias, such as ventricular fibrillation.

3.2. Ventricular Fibrillation (VF)

VF occurs when the ventricles quiver instead of contracting normally due to disorganised electrical activity. This results in the ventricles not being able to pump blood effectively to the rest of the body. Ventricular fibrillation tends to occur mostly in diseased hearts. However, in rare cases it can occur in individuals with structurally normal hearts and lead to sudden death.


The doctor will take a complete medical history and give you a physical examination.
 

Tests that can be used to determine the type of arrhythmias are:


Palpitations (conscious feeling of the heart beating) described as:
  • Missed beats
  • Skipped beats
  • Fluttering in the chest 
  • Racing heart rate
  • Fainting
  • Chest pain
  • Shortness of breath

1. Electrophysiological Study (EPS)  

1.1. What is it?

An electrophysiological study (EPS) is a specialised cardiac procedure performed when your doctor suspects that you have abnormal heart rhythms and/or conduction disorders. 

It may be used to evaluate symptoms of:
  • Palpitations
  • Unexplained fainting
  • Potentially life-threatening heart rhythms that may cause sudden cardiac death
A cardiac EPS helps the cardiologist to identify:
  • The disturbance of your heart rhythm
  • The cause of this disturbance
  • Choose the best method of treatment

During the EPS, the electrical behavior of the heart that is responsible for controlling your heartbeat is recorded by placing conducting wires (or leads) positioned at strategic locations within your heart. Through these leads, the electrical conduction of the heart can be studied, and any abnormal conduction can be identified.

1.2. Why is it done?

The EPS is used to detect and diagnose any abnormal conduction of electrical impulses that may be responsible for heart rhythm disturbances. 

It is also useful in determining how effective medications are in controlling abnormal heart rhythms.

Heart rhythm abnormalities are often the result of electrical "short circuits" in the heart. These may be treated using radiofrequency energy to eliminate (ablate) areas of abnormal conduction.

1.3. What to expect?

1.3.1. Before the test

Performing an EPS will require admission to the hospital the day before the test and 2-3 days stay after. Your doctor will also go through the reasons, goals and risks of the procedure.

Once you are admitted to the ward, the following will be carried out to prepare you for the procedure:

  • Preparatory blood tests 
  • If you're a woman of childbearing age, you may be required to take a urine pregnancy test
  • An electrocardiogram
  • Agreeing to undergo EPS by signing a consent form 
  • A small needle (heparin plug) will be inserted into one of the veins in your hand to facilitate injections of medication during the test, if necessary
  • You will not be allowed to consume food and drinks from midnight on the day of the test until after the procedure is completed
  • Your groins and chest may be shaved just before the test

1.3.2. During the test

The EPS is performed in the Invasive Cardiac Laboratory by the cardiac electrophysiologist (a trained specialist who performs this test) and may take about 2 hours. It may sometimes be longer for complex cases.

  • Medication to help you relax or sleep will be given to you through the heparin plug.
  • You will need to lie fairly still throughout the study.
  • Some long complex procedures may be done under general anaesthesia.
  • After an injection of local anaesthesia, several leads will be inserted through your groin.
  • Using an X-ray to guide the wires, the leads are advanced into the heart.
  • When the leads are placed at the desired locations in the heart, the electrophysiolgist will:
    • Record the electrical activities in your heart.
    • Stimulate your heart with mild electrical current to evaluate the response.
    • Confirm the nature of the arrhythmia if it is induced. 
    • Perform ablation to eliminate or modify the arhythmia.

While the test is being performed, you may experience palpitations (a sensation of the heartbeat). However, if you experience any discomfort during the procedure, please inform the electrophysiologist.

When the examination is completed, the leads will be removed and the tiny wounds at the puncture sites will be compressed for a few minutes to stop bleeding. The wounds should heal within a few days.

 1.3.3. After the test

  • After the test, you will need to lie in bed for about 4-8 hours.
  • You will also be advised on moving the limbs, which the leads had been inserted in to aid the healing of the blood vessels and avoid bleeding.
  • If you feel pain or swelling in the punctured areas, you must inform the nurse, and if necessary, painkillers will be prescribed.
  • You will be able to go home the next day.

1.3.4. What to prepare

  • You may be advised to stop taking certain medications before your EPS.
  • Inform your doctor of any allergy, especially allergies to X-ray contrast medium (dye), any heart rhythm medications and pain-relieving medication.
1.3.5. After being discharged
 
  • You should be able to resume most of your usual activities the day after your discharge.
  • Avoid any heavy lifting or strenuous exercise for a week to minimise the chance of bleeding from the access sites.
  • However, should the need arise, medical leave may be issued to allow you to rest at home.
  • Cover the punctured wounds with waterproof plasters for 2 days. 
  • Thereafter, the wounds can be left exposed or covered with a simple plaster like Handiplast.

1.4. What are the potential risks or complications?

The EPS is an extremely safe procedure. 

Most complications are minor:
  • Pain
  • Swelling
  • Bruising and bleeding from the puncture sites

Occasionally, abnormal heart rhythms may occur during the procedure. On rare occasions, major complications can occur. Your doctor will go through these in detail with you during the consent process.

Pregnant women should not undergo this test due to the exposure to X-ray radiation.

1.5. When will you get the results?

The electrophysiologist will usually inform you of the results of the study during or some time after the procedure, before you are discharged. 

He/She will also discuss with you about the treatment options, if necessary.

2. Genetic Testing and Specialised Genetic Counselling

Genetic testing and specialised genetic counselling are offered by NUHCS for various heart conditions.

2.1.  Cardiomyopathies

  • Hypertrophic cardiomyopathy
  • Dilated cardiomyopathy
  • LV hypertrabeculation
  • LV non‐compaction cardiomyopathy
  • Arrhythmogenic right ventricular cardiomyopathy
  • Fabry disease

2.2.  Aortopathies / Congenital Connective Tissue Disorders

  • Marfan syndrome
  • Loeys‐Dietz syndrome
  • Ehlers‐Danlos syndrome

2.3. Inherited arrhythmias / channelopathies

  • Long QT syndrome
  • Brugada syndrome
  • Catecholaminergic polymorphic ventricular tachycardia
  • Short QT syndrome

The treatments for arrhythmias include either one or a combination of:

  • Lifestyle changes such as,
    • Stop smoking, if you do
    • Avoiding activities that trigger the arrhythmia
    • Staying away from stimulants including caffeine, alcohol, certain cough or cold medications
  • Medication
    • Anti-arrhythmic drugs that control the heart rate
    • Anti-coagulant or anti-platelet therapy that reduce the risk of blood clot formation in your heart
  • Surgery
    • Implantation of devices such as pacemakers, defibrillators, ventricular assist devices (VADs)
    • Electrophysiology study (EPS) with radiofrequency
Your cardiologist will recommend the type of treatment depending on the type, cause and condition of the disease.
 

1. Pacemakers, Defibrillators and Cardiac Implants

1.1. Pacemakers

1.1.1. Overview

Arrhythmias

Pacemakers are devices that help to stabilise the heart’s rhythm and are usually implanted into the heart when the heart rate is too slow. 

The pacemaker device comprises of 2 parts:

  • The pacemaker box (also known as the pulse generator) which contains the battery and electrical circuitry that controls the pacemaker. 
  • Wires (also called leads) that carry electrical impulses to the heart that allows it to beat at a rate determined by the pacemaker.

Pacemakers are:

  • Reliable
  • Unobtrusive
  • Do not affect a patient’s daily activities

There are now "leadless" pacemakers without wires , that are used mainly in patients with no/limited vascular access.

Most patients notice an improvement in their conditions and symptoms after the insertion of a pacemaker.

Sometimes, pacemakers are implanted for patients with severe heart failure (see "Cardiac Resynchronisation Therapy") to improve their heart function.

1.1.2. Why do you need a cardiac pacemaker?

Excessively slow heart rhythms can severely affect the heart's ability to pump blood throughout the body. This may cause symptoms such as:

  • Fatigue
  • Dizziness
  • Shortness of breath
  • Fainting
  • In extreme circumstances, death

In such cases, your doctor may recommend a permanent pacemaker to be implanted.

1.1.3. What should you expect?

Though the procedure itself only takes about an hour, you will need to stay in hospital for one day for the pacemaker implantation. 

Before the procedure:

  • Some routine blood tests and electrocardiograms may be performed.
  • You will be required to sign a consent form after your doctor explains the procedure and its risks.
  • A small needle is inserted in one of the veins on your hand to facilitate the injection of medication.
  • You will be asked to fast on the night before the procedure.

During the procedure:

Arrhythmias
  • The procedure is performed in the Invasive Cardiac Laboratory.
  • Insertion is done under sedation and a local anaesthetic.
  • A small incision is made in the skin just under the collarbone.  
  • A small “pocket” is created under the skin where the incision was made to house the pacemaker box.
  • An insulated lead (wire) is then inserted through a vein in the upper chest.
  • Guided by X-ray, it is threaded until its tip lies snugly within the heart. 
  • The other end of the lead is then connected to the pacemaker.
  • Once the leads are positioned, an electrical test is done to ensure that the pacemaker is working correctly.
  • The leads are then connected to the pacemaker and the incision is closed. 
  • At the end of the procedure, all that is visible is the closed incision line.

After the Implantation:

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On returning to the ward,

  • You will be given regular antibiotic injections to reduce the risk of infection.
  • Please inform the attending nurse if you experience pain at the implant site; painkillers can be prescribed.

On the following day,

  • You will be sent for a chest X-ray to check the position of the pacemaker and wire, and to look for potential complications.
  • The pacemaker will also be checked to programme by a technologist. This is done wirelessly. 
  • Most patients can be discharged one day after the procedure.

On returning home,

  • You can resume most daily activities within a few days.
  • Ensure that the wound on the chest remains dry. 
  • The waterproof dressing applied to the wound need not be changed till review in the clinic in 10 to 14 days.
  • The stitches are absorbed naturally and do not need to be removed.
  • Your doctor will arrange a schedule of periodic checks, and will electronically program the pacemaker's behavior to suit your requirements.

1.1.4. What are the potential risks or complications?

The risks associated with the procedure are very low.

These include:

  • Bleeding (from insertion of leads into the veins)
  • Temporary injury to the lung
    • Pneumothorax occurs infrequently when air leaks into the chest cavity causing the lung to collapse 
    • It is reversible and treated with the insertion of a tube into the chest to allow the lung to re-expand
  • Infection of the pacemaker and lead systems
  • This rarely occurs, and may require further antibiotics and removal of the pacemaker system

1.1.5. What should you do after the pacemaker implantation?

You should watch for fever, excessive pain, redness or swelling over the wound. Inform your doctor immediately if you have these symptoms.

Avoid excessive movement of the arm on the side of the pacemaker insertion. Avoid lifting the arm above your head and lifting more than 5 kg load for 2 weeks after the implantation.

Complete the course of antibiotic medication prescribed on discharge.

Remember to inform all your attending doctors that you have a permanent pacemaker. Some important reasons for this include:

  • The use of short-wave diathermy a form of treatment for example in rheumatism or diathermy used during surgery near where the pacemaker is should be avoided
  • You should avoid have magnetic resonance imaging (MRI) tests done as well

If you have any queries regarding anything about the procedure or how to take care of yourself after the procedure, please contact your doctor.

1.2. Implantable cardiac defibrillators 

These are used when patients are deemed to be at very high risk of sudden cardiac death from lethal heart rhythm disorders (arrhythmias). 

These sophisticated devices monitor the heart rhythm continuously and attempt to terminate these life-threatening rhythm disorders if they occur. 

This can be through rapid pacing or delivery of an electrical shock to "reset" the heart to normal rhythm.  

They are implanted the same way as pacemakers.

1.3. Implantable loop recorders 

These are small devices inserted under the skin on the chest wall to monitor a patient's heart rhythm for prolonged periods of time (up to about 3 years).

They do not have any wires and may be used in certain situations such as recurrent fainting spells where a heart rhythm disorder is suspected as the cause but not documented previously.

2. Transcatheter left atrial appendage closure 

2.1. Overview

The left atrial appendage is an outpouching structure connected to the left atrium of the heart (left upper heart chamber). This is a normal heart structure and does not cause problems for most people. However, it can be a source of clot formation in patients with atrial fibrillation (AF).

Arrhythmias

The occurrence of AF in Singapore is approximately 1.5% (that is 1.5% of Singaporeans may have AF) but this is likely to increase as the population ages. It is the most common significant type of irregular heart rhythm in Singapore but most importantly, it is the biggest risk factor causing stroke.

During AF, there is ineffective blood flow in the upper heart chambers leading to stagnation of blood in the left atrium. It has been shown that the majority of blood clots in patients with AF reside in this left atrial appendage. 
 
Current evidence shows that the transcatheter left atrial appendage device closure is effective in reducing the risk of clot related complications associated with non-valvular causes of AF.
 

2.2. What are the options available to reduce the risks of stroke in patients with AF?

Though there are a variety of options available to reduce the risks of stroke in patients with AF, there is no single option that would be appropriate for every patient. 

Your doctor will discuss these options with you and advice you on the option that is best suited for your condition. There are however several standard therapeutic options that you should be aware of. These include:
  • Administration of blood thinners
  • Open surgery to remove the left atrial appendage
  • Transcatheter atrial appendage closure

2.3. What is transcatheter left atrial appendage device closure?

This is a procedure where devices designed specifically to fit the left atrial appendage is delivered through a long, thin tube (catheter) to seal the orifice of the atrial appendage. 

With time, tissue growth around and over the device will occur preventing further clot formation and migration.

2.4. How is this done?

This procedure is done under general anesthetic in a heart catheterisation laboratory.

It takes approximately 1-2 hours.

Transesophageal echocardiogram (a type of ultrasound for the heart) and fluoroscopy (a special X-ray using dye) are used to monitor the procedure.

A soft catheter (tube) is first introduced into the leg vein and then positioned across the atrial septum.

The left atrial appendage closure device is then delivered to its intended position and released.

2.5. What happens after the procedure?

  • Once you are awake from the anesthesia, you will be transferred to the cardiac monitoring unit for 24 hours.
  • Most patients can be discharged 2-3 days after the procedure.
  • The recovery time differs from patient to patient.
  • You will be advised to avoid strenuous activities for 1 month after the procedure.
Arrhythmias

2.6. What are the risks involved in this procedure?

There are certain potential risks associated with any interventional procedure as well as risks specific to the device. Your doctor is the best person to provide you with accurate information and assessment of these risks. You should speak to him/her to address your concerns fully.
Potential risks include but are not limited to:
  • Air embolus
  • Allergic reactions to any medications given before, during or after the procedure
  • Allergic reaction to the dye administered during the procedure
  • Reaction to the drugs given for anaesthesia
  • Arrhythmia during the procedure
  • Bleeding 
  • Cardiac arrest – when the heart stops
  • Cardiac tamponade - bleeding outside the heart between the heart muscle and the lining of the heart
  • Death 
  • Device migration or embolisation
  • Embolic event - where particles of clot/air travel and obstruct blood flow
  • Fever
  • Foreign body embolisation
  • High or low blood pressure
  • Infections
  • Heart attack
  • Perforation
  • Renal failure
  • Stroke
  • Blood clot formation
  • Access site complications such as vessel injury
  • Valve dysfunction

Cardiac Electrophysiology Study (EPS) and Radiofrequency Ablation (RFA)

Cardiac Electrophysiology Study (EPS) and Radiofrequency Ablation (RFA)

Permanent Cardiac Pacemaker Insertion

Permanent Cardiac Pacemaker Insertion

Implantable Cardioverter Defibrillators & Cardiac Resynchornisation Therapy

Implantable Cardioverter Defibrillators & Cardiac Resynchronisation Therapy






For referrals:
Associate Professor Roger Foo
MD, MBBS, MRCP, FAHA 

Senior Consultant Yasmin Bylstra 
BSc (Hons), Gdip GC, FHGSA (Genetic Counselling) 

National University Heart Centre, Singapore: 
Inherited Cardiac Conditions Clinic 
email: cardiac_clinics@nuhs.edu.sg
call: +65 6808 8232 (Mon–Fri 0830 – 1700 GMT+8)

Arrhythmias

Research Study
Genome Sequencing for Healthy Elderly in Singapore
Actively seeking elderly Singaporeans aged 80 - 90 and have no chronic disease, such as high blood pressure and diabetes, to donate a blood sample for DNA sequencing. 
Contact: A/Prof Roger Foo, 6808 8232 or mdcrfsy@nus.edu.sg

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