Arrhythmias

Tachycardia
(includes Atrial Fibrillation, Super Ventricular Tachycardia, Ventricular Tachycardia)

What is an arrhythmia?

Our heart is controlled by very small regular electrical impulses causing the heart to beat in a steady rhythm.
Arrhythmia means abnormal rhythm and is caused by a disturbance in the electrical impulse controlling the heart rhythm.

Sometimes arrhythmias happen so quickly that the rhythm isn't affected much but arrhythmias which last for a long time can stop the heart pumping properly.

Bradycardia

Bradycardia means a slow heart rate, less than 60 beats per minute. This may not cause you any problems depending on your age, fitness, and activity levels.

Sinus bradycardia is a normal, but slow heart rhythm which normally does not cause you problems. Some very fit athletes have a very slow heart rate (30-40 beats per minute) but remain well with it.

If bradycardia does cause you problems, these may include:

· breathlessness
· dizziness, especially when standing
· lethargy
· collapse

Tachycardia

Tachycardia means fast heart rate, more than a 100 beats per minute. Tachycardia can either have a regular or irregular rhythm.

1. Fast regular beats: If your heart is beating regularly but too fast, it may be caused by normal sinus tachycardia. This is usually caused by exercise, which increases your need for oxygen so your heart rate gets faster to meet this demand. It can also be caused by a fever, having too little iron in your body, having an overactive thyroid gland, or a release of adrenaline when you are stressed or scared.

2. Fast Irregular Beats:

Atrial fibrillation (AF) is a very common condition. The atria (top two smaller chambers of the heart), beat very fast and irregularly, up to 400 beats per minute. Only a small amount of these beats get passed through to the lower chambers so the blood may not get passed around the heart properly. Episodes can last a few minutes, hours or can be permanent and may cause unpleasant palpitations and breathlessness.

AF needs investigation and treatment but is not usually immediately dangerous.
However, if you are short of breath, have chest pain or feel faint dial 111 and ask for an ambulance.

Causes include:

· coronary artery disease
· damaged heart valve
· overactive thyroid

Treatment includes:

Medication to prevent AF happening again, stabilise your heart rate, and prevent blood clots
Cardioversion may be performed to stop permanent AF
Catheter Ablation or Pacemaker

Do you want more information on AF?? Order a FREE AF booklet: call 044962277 or email info@nzgg.org.nz
and ask for Order Number HP:4286

Supra-ventricular tachycardia (SVT) is a disturbance of the rhythm of the heart caused by rapid electrical activity in the upper parts of the heart (atria). The heart beats very fast, 140-240 beats per minute. Common symptoms include:

· discomfort
· palpitations (you feel aware that your heart is beating fast)
· dizziness
· nausea
· faintness

Please note: There are a special group of SVTs that are caused by electrical impulses traveling along the wrong pathway between the atria and ventricles. These occur in people with Wolff-Parkinson-White Syndrome (WPW). If you have this syndrome you will need to see a specialist for detailed heart tests.

Ventricular tachycardia (VT) is an abnormal heart rhythm that starts in the ventricles (the larger lower chambers of the heart). The heart usually beats fast; 120-200 beats per minute. This may last any time from only a few seconds to hours.

Symptoms include:

· faintness,
· fast regular palpitations with breathlessness
· occasionally chest pain.

If you think or know that you are likely to have an episode of VT, feel your pulse and if it is too fast to count and you get these symptoms dial 111 and ask for an ambulance. This can be life threatening.

Heart Block

Heart block occurs when the regular electrical impulses in your heart do not work properly. An electrocardiogram (ECG) can identify the different degrees of heart block. There are three different types of heart block:

· First degree: The impulses are slowed but the heart rate and rhythm remain normal and no treatment is required
· Second degree: Some impulses get blocked. You may have no symptoms, or you may feel dizzy, unwell or tired. You are likely to need treatment.
· Third degree or complete heart block: None of the impulses are working properly. You may feel dizzy, unwell or faint and you will need medical treatment.

Causes of heart block include angina, heart attack and certain drugs. Treatment will depend on what is causing it.

How are arrhythmias diagnosed?

Your doctor will examine you and ask you to tap out the rhythm you feel with your hand. Try to keep a record of when you experience an arrhythmia and how long it lasts for.

You will have an electrocardiogram (ECG) which may help to find out why your heart is not beating normally. Sometimes an exercise ECG is used to find out what happens to the arrhythmia when you exercise.

When arrhythmias don't happen often enough to show up on an ordinary ECG, a Holter monitor is worn to record the rhythm over a 24-48 hour period. You will be asked to keep a simple diary of the activities you do, and note times that you have palpitations or other symptoms you associate with an arrhythmia.

Electrophysiological studies may be required to see where the arrhythmia is coming from.

How are arrhythmias treated?

AVOID THE TRIGGER: arrythmias can be triggered by exercise, being upset or by drinks such as coffee, alcohol or sports drinks or some over-the-counter cold remedies. You may be able to prevent it by avoiding the trigger.

Treatment may include one or more of the following: