Introduction
Arrhythmias are disorders of cardiac rate, rhythm and conduction.
They can be classified as bradyarrhythmias (heart rate < 60 per minute) and tachyarrhythmias (heart rate > 100 per minute).
Bradyarrhythmias include sinus bradycardia, sinus pauses and atrioventricular blocks.
The tachyarrhythmias can further be classified into supraventricular and ventricular arrhythmias, based on their site of origin.
Tachyarrhythmias include atrial fibrillation, atrial flutter, paroxysmal supraventricular tachycardia, ventricular tachycardia and ventricular fibrillation.
Prior to drug treatment of a suspected cardiac arrhythmia, a 12-lead ECG must be done to confirm the rhythm abnormality.
It is dangerous to use an antiarrhythmic drug without doing an ECG.
Refer symptomatic patients to hospital immediately.
The choice of drug treatment depends on the type of arrhythmia and severity of symptoms.
Causes of Cardiac arrhythmias
The causes of Cardiac arrhythmias include the following:
- Rheumatic heart disease
- Other valvular heart diseases
- Hypertensive heart disease
- Ischaemic heart disease
- Thyrotoxicosis
- Hypothyroidism
- Cardiomyopathies
- Complete heart block
- Electrolyte abnormalities particularly hypokalaemia
- Pericardial disease
- Drugs
- Smoking, alcohol, coffee, tea, etc.
- Pulmonary embolism.
- Post cardiac surgery
- Idiopathic
Symptoms of Cardiac arrhythmias
- Palpitations
- Dizziness
- Chest discomfort/pain
- Fatigue
- Difficulty in breathing
- Sudden collapse
- Sudden death
Signs of Cardiac arrhythmias
- Rate may be fast, slow or normal
- Pulse
- Rhythm
Regular
- Sinus tachycardia
- Sinus bradycardia
- Complete heart block
- Supraventricular tachycardia
- Ventricular tachycardial
Regularly irregular
- Supraventricular or ventricular ectopic beats
Irregularly irregular
- Atrial fibrillation
- Atrial fibrillation Atrial flutter (with variable atrio-ventricular block)
- Multiple supraventricular or ventricular ectopic beats
- Pulse deficit (apical rate faster than radial pulse rate; seen in fast atrial fibrillation or flutter)
- Hypotension or blood pressure may be unrecordable
- Signs of heart failure (may be present)
Investigations
- 12-lead ECG
- Serum electrolytes (including magnesium, calcium)
- Thyroid function tests
- Chest X-ray
- Ambulatory ECG (Holter)
- Echocardiography
Treatment for Cardiac arrhythmias
Objectives
The treatment objectives of Cardiac arrhythmias include the following
- To control ventricular rate
- To restore sinus rhythm
- To relieve symptoms
- To improve functional capacity and quality of life
- To prevent or treat associated complications
- To treat the underlying condition e.g. thyrotoxicosis
- To prevent stroke or systemic thromboembolism
- To reduce morbidity and mortality
Non-pharmacological treatment
- Reassure the patient
- Avoid excessive intake of alcohol, coffee or tea and stop smoking (if these are possible precipitating factors)
- Massage of the carotid sinus on one side for a few seconds. This may terminate an attack of paroxysmal supraventricular tachycardia
- Electrical cardioversion
Pharmacological treatment
A. Fast atrial fibrillation or atrial flutter-for rate control
1st Line Treatment
Evidence Rating: [A]
Atenolol, oral,
Adults: 50-100 mg daily
Children:
- 12-18 years; 25-50 mg daily
- 1 month-12 years; 12.5-50 mg daily
Neonates: Refer to a paediatrician
Or
Bisoprolol, oral,
Adults: 2.5-10 mg daily
Children: Safety not establised in children
Or
Metoprolol tartrate, oral,
Adults: 50-100 mg 8 or 12 hourly daily (max. 300 mg daily)
Children
- 12-18 years; 50 mg 8 or 12 hourly daily (max. 300 mg daily)
- < 12 years; refer to a paediatrician
Note
Avoid if beta-blockers are contraindicated e.g. bronchial asthma, hypotension
Or
Verapamil, oral,
Adults: 40-120 mg 6-8 hourly (max. 480 mg daily)
Children: Refer to a paediatrician
Note
Avoid use in patients already on beta-blocker
2nd Line Treatment
Evidence Rating: [A]
Digoxin, oral,
Adults: 125-250 micrograms daily
Children: Refer to a paediatrician
B. Fast atrial fibrillation or atrial flutter-for rhythm control
This is required to restore sinus rhythm.
Refer to a cardiologist, physician specialist or paediatrician as appropriate.
C. Paroxysmal supraventricular tachycardia
1st Line Treatment
Evidence Rating: [A]
Atenolol, oral,
Adults: 50-100 mg daily
Children:
- 12-18 years;
- 1 month-12 years;
- Neonates: Refer to a paediatrician
Or
Bisoprolol, oral,
- Adults 2.5-10 mg daily
Children: Safety not established in children
Or
Metoprolol tartrate, oral,
Adults: : 50-100 mg 8 or 12 hourly daily (max. 300 mg daily)
Children
- 12-18 years; 50 mg 8 or 12 hourly daily (max. 300 mg daily)
- <12 years; refer to a paediatrician
Note
Avoid if beta-blockers are contraindicated e.g. bronchial asthma, hypotension
Or
Verapamil, oral,
Adults: 40-120 mg 6-8 hourly (max. 480 mg daily)
Children: Refer to a paediatrician
Note
Avoid use in patients already on beta-blocker
2nd Line Treatment.
Evidence Rating: [A]
Digoxin, oral,
Adults: 125-250 micrograms daily
Children: Refer to a paediatrician
D. Prevention of stroke or systemic thromboembolism in atrial fibrillation or flutter
Patients should be given long-term anticoagulation.
(See options for long-term anticoagulation on ‘DVT‘ or ‘Pulmonary Embolism‘).
Referral Criteria
Refer all patients to a cardiologist, physician specialist or paediatrician for further evaluation and management after the initial treatment.
All symptomatic patients, as well as those who cannot have an ECG done or interpreted, or who present with heart failure, should be referred immediately.