When electrical signals in the heart are disrupted this can cause ‘arrhythmias’. ‘Arrhythmia’ is a general term for any abnormal heart rhythm, where the heart is not beating in ‘sinus rhythm’. The heart beats either too fast, too slow or irregularly.
Some arrhythmias are harmless. Others require treatment with medication, surgery or devices.
Note: arrhythmias are sometimes referred to as ‘dysrhythmia’, and either term can be used
What is a normal heart rhythm?
A normal ‘resting’ heartbeat is usually between 60 and 100 beats per minute in an adult.
The speed at which the heart beats (pumps blood out) will vary and depends on what the person is doing.
For example, the heart beats more quickly when someone is exercising, and their body needs more oxygen to get to the muscles than when someone is resting.
What is the effect of arrhythmias?
Arrhythmias can reduce how well the heart beats and pumps blood around the body. This is because the heart’s chambers are uncoordinated or unable to pump properly.
You might feel:
- A pounding or fluttering feeling in your chest
- Dizzy or lightheaded
- Loss of consciousness (fainting)
However, some arrhythmias are more persistent, or can have serious consequences. As they reduce how effective the heart is at pumping blood around the body, they can be life-threatening.
Types of arrhythmia
Below are different types of arrhythmia that may occur in people with cardiomyopathy.
- Atrial fibrillation (AF)
- Atrial flutter
- Bundle branch block (BBB)
- Heart block
- Ventricular fibrillation (VF)
- Ventricular tachycardia (VT)
How are arrhythmias treated?
- Taking anti-arrhythmic medication
- Monitored via an ICD
Amiodarone
Amiodarone is prescribed to help regulate your heart’s rhythm and rate, it is an anti-arrhythmic medication used to treat abnormal heart rhythms. Amiodarone is initially prescribed 3 times daily to begin with then reduced to twice daily and once daily, it is available in 100mg or 200 mg tablets. The usual maintenance dose is 200mg daily.
Possible side effects of Amiodarone are:
- Feeling sick (nausea), reduced appetite or constipation.
- A metallic taste in the mouth
- Slow heart rate
- Reversible deposits in the eye (micro corneal deposits- changes to the colour of the front part of the eye), blueish halo (bright circle which surround a light source- such as headlights) or blurred vision (inability to detect the details of an object).
- Photophobia (sensitivity to light) or visual impairment (loss of sight)
- Skin rash, discolouration or photo sensitivity (skin can become sensitive to sunlight)
- Change in thyroid function- tiredness, heat or cold intolerance, weight loss or gain, heart pounding, light-headedness, restlessness, irregular menstrual periods or poor concentration
- Lung fibrosis or pneumonitis- cough, wheezing or difficulty in breathing
- Liver impairment- yellow tinge to the skin, brown or dark coloured urine, sweating or weight loss
Some medications can interact with Amiodarone, our advice is to check with your hospital or community pharmacist before taking any other medications including over-the-counter medications, herbal or complementary medicines.
The following are known to react with Amiodarone:
- Grapefruit juice - this can increase the amount of Amiodarone absorbed from the stomach so it is best avoided while taking Amiodarone.
- St John’s Wort – a herbal supplement.
- Medicines that can slow heart rate - beta blockers, Verapamil, Diltiazem. These are sometimes prescribed alongside Amiodarone but careful monitoring will be needed.
- Warfarin - Amiodarone may increase the effect of warfarin. Additional blood tests are needed when Amiodarone is started, increased or decreased or stopped.
Anti-arrhythmic medicines
Digoxin- The dose of Digoxin will need to be adjusted if Amiodarone is started.
Medicines that prolong the QT interval: other medicines that are used to control heart rhythms may need to be adjusted.
People taking Amiodarone are advised to protect themselves from the sun by wearing protective clothing and using a wide-spectrum sunblock. Your cardiologist / cardiac nurse or GP should periodically check your thyroid function, liver and kidney function whilst you are taking Amiodarone by taking a blood test.