Arrhythmias

Arrhythmias occur when the electrical impulses controlling the heartbeat are disrupted. Several factors can contribute to this condition, including:

• Coronary Heart Disease (CHD): Narrowed arteries reduce blood supply to the heart, affecting its electrical activity.
• High Blood Pressure (Hypertension): Increases strain on the heart, potentially leading to electrical instability.
• Heart Valve Disease: Malfunctioning valves can cause abnormal blood flow, triggering arrhythmias.
• Electrolyte Imbalances: Abnormal levels of potassium, calcium, or magnesium can disrupt the heart’s electrical signals.
• Genetic Conditions: Some arrhythmias are inherited, such as Brugada syndrome or Long QT syndrome.
• Congenital Abnormalities: Accessory pathways, like those seen in Wolff-Parkinson-White syndrome, provide an extra electrical connection in the heart, leading to rapid heart rates.
• Medications and Stimulants: Certain drugs, excess caffeine, alcohol, or recreational substances can provoke arrhythmias.

Arrhythmias are categorized based on whether the heart beats too fast (tachycardia), too slow (bradycardia), or irregularly. Key types include:

1. Atrial Arrhythmias (Affecting the Upper Chambers of the Heart)

Atrial Fibrillation (AF):

• The most common arrhythmia, affecting over 1.5 million people in the UK.
• The heart’s upper chambers (atria) quiver instead of contracting properly, leading to an irregular and often rapid heartbeat.
• Increases stroke risk five-fold due to the potential formation of blood clots in the atria.

Atrial Flutter:

• Similar to AF but with a more organized rhythm.
• Can cause palpitations, dizziness, and shortness of breath.
• Supraventricular Tachycardia (SVT):
• A fast heartbeat originating above the ventricles.
• Often causes sudden episodes of rapid heart rate.

2. Ventricular Arrhythmias (Affecting the Lower Chambers of the Heart)

Ventricular Tachycardia (VT):

• A fast, dangerous heart rhythm originating in the ventricles.
• Can lead to dizziness, fainting, or sudden cardiac arrest.

Ventricular Fibrillation (VF):

A life-threatening condition where the heart quivers chaotically, failing to pump blood.

• Immediate defibrillation (electric shock) is required to restore normal rhythm.

3. Bradycardias (Slow Heart Rhythms)

Sinus Bradycardia:

• A slow but normal rhythm, common in athletes.
• Can cause dizziness or fainting if the heart rate is too low.

Heart Block:
The electrical signals are partially or completely blocked, slowing the heart rate.

• May require a pacemaker if severe.

4. Vasovagal Syncope

Vasovagal Syncope:

• A common cause of fainting, occurring when the body overreacts to certain triggers, such as the sight of blood or emotional distress.
• This overreaction leads to a sudden drop in heart rate and blood pressure, resulting in reduced blood flow to the brain and fainting.
• Symptoms may include dizziness, nausea, and sweating prior to losing consciousness.

Arrhythmias do not always cause noticeable symptoms, but some individuals may experience:
•       Palpitations (a feeling of a racing or irregular heartbeat)
•       Ectopic Beats (unusual extra or skipped heartbeats)
•       Dizziness or Fainting (Syncope)
•       Shortness of Breath
•       Fatigue and Weakness

Severe arrhythmias can lead to cardiac arrest, requiring immediate emergency care.

1. Diagnosis

• Electrocardiogram (ECG): The primary test to detect abnormal heart rhythms.
• Holter Monitor: A 24-48 hour ECG recording to detect intermittent arrhythmias.
• Echocardiogram: Assesses heart structure and function.
• Electrophysiology Study (EPS): A specialized test to map the heart’s electrical pathways.

2. Treatment Options
Treatment depends on the type and severity of the arrhythmia:

• Lifestyle measures

Medications:

• Beta-blockers and Calcium Channel Blockers: Help slow down rapid heart rates.
• Anticoagulants (Blood Thinners): Reduce the risk of stroke in atrial fibrillation.

Medical Procedures:

• Cardioversion: Uses an electrical shock to restore normal rhythm (commonly used for AF).
• Catheter Ablation: Destroys the abnormal electrical pathways causing arrhythmia.

Implantable Devices:

• Pacemaker: Regulates slow heart rhythms (bradycardia).
• Implantable Cardioverter Defibrillator (ICD): Shocks the heart if a dangerous rhythm is detected, preventing sudden cardiac arrest.