Arrhythmias

Definition

The heart should work in a regular, steady pattern. Arrhythmias are breaks in the pattern. It may happen in a short burst or last over long periods of time.

Types of arrhythmias are:

• Very slow heart rate— bradycardia
• Very fast heart rate— tachycardia
• Uneven rhythm
• Skipped contractions (beats) of the heart

Most will not affect overall health. Some arrhythmias can slow the flow of blood to the body or increase the risk of other health problems such as stroke.

Causes

The action of the heart is controlled by an electrical signal. The signal starts in a group of cells called the sinoatrial (SA) node. The signal moves from the top to the bottom of the heart. The heart will contract first in the upper areas of the heart (atria). Next, it contracts in the lower areas of the heart called (ventricles). Arrhythmias may happen if:

• The sinus node is damaged and cannot send normal electrical signals
• The electrical signal cannot travel smoothly through the heart
• Other influences like hormones or drugs make the SA node overreact
• Other areas of the heart start an action that does not match the pattern of the SA node

Conduction Pathways of the Heart.

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Risk Factors

The risk of arrhythmias increases with age. Other things that may increase the risk are:

• Excess caffeine, stress, smoking , alcohol use disorder , or cocaine abuse
• Certain medicine, such as diet pills, decongestants, and antidepressants
• Heart-related conditions, such as:
  • Coronary artery disease (CAD)
  • Problems with heart valves
  • Rheumatic heart disease
  • Cardiomyopathy
  • Previous heart attack —may cause scarring that make it difficult for electrical signals to pass
• Medical conditions, such as anemia , high blood pressure , diabetes , liver disease, endocrine disorders (thyroid or adrenal gland problems), or typhoid fever
• Accidents or injuries such as electric shock or lightning strike, near-drowning , or hypothermia

Symptoms

Not all arrhythmias will cause symptoms. Some arrhythmias may be felt as a fluttering in the chest, skipped heartbeat, or fast heartbeat.

Some arrhythmias slow the flow of blood through the heart. This will also slow the flow of blood to the body. If the flow is slowed enough it can lead to:

• Fainting
• Lightheadedness
• Weakness
• Tiredness
• Shortness of breath
• Chest pain

Diagnosis

The doctor will ask about symptoms, past health, and family history. A physical exam will be done. The electrical activity of the heart can be checked with :

• ECG —Records the heart's activity for a period of time.
• Holter monitor —An ECG that records heart activity over 24 to 48 hours. It can help find arrhythmias that do not occur in a regular pattern.
• Exercise stress test —An ECG that is taken during a physical activity. It can help find arrhythmias that only appear with physical stress.
• Electrophysiological study —Wires are passed through blood vessels to the heart. The wire sends electrical signals to the heart to try to start an arrhythmia. This will help to find where the arrhythmias is starting in the heart.

To look for causes, the doctor may also order:

• Blood tests and urine tests—to look for stimulants in the blood that may cause rhythm changes
• Tests to look for structure problems such as:
  • Echocardiogram
  • Nuclear scanning
  • Coronary angiography

Treatment

Not all arrhythmias need to be treated. Many are harmless and will not cause problems.

Treatment may be needed for arrhythmias that affect daily life. It may also be needed for those that raise the risk of other problems like stroke. In this case, the goal of treatment is to return the heart to a normal rhythm. The type of treatment will depend on the arrhythmia and overall health. It may include:

• Medicine—to slow down or speed up the heart rate or treat the cause.
• Cardioversion—send an electrical signal to reset the pattern of the heart.
• Medical device implantation—placed by the heart to track and correct the heart's activity. Types of devices include:
  • Implantable cardioverter defibrillator (ICD)—The device will shock the heart when a dangerous arrhythmia happens.
  • Artificial pacemaker —Provides regular electrical signals to keep the heart in a steady rhythm.
• Procedures to change tissue in small areas of the heart. The area will block the flow of bad electrical signals. It can also stop some signals from starting.
  • Ablation —An area of the heart that starts a bad electrical signal is removed or scarred.
  • Maze procedure and mini-maze procedure —A pattern of scar tissue is made in the upper chambers of the heart. It makes a special path for the electrical signal to pass.

Prevention

Not all arrhythmias can be prevented. To help reduce the risk of certain arrhythmias:

• Follow the care plan for other heart or medical issues.
• Avoid substances that trigger arrhythmia or make it worse. This includes caffeine, alcohol, or tobacco.
• Follow general advice for a healthy heart:
  • Maintain a healthy weight.
  • Talk to the doctor about a safe exercise program.
  • Do not smoke. If you smoke, find out ways you can quit.
  • Eat a healthful diet that is low in saturated fat and rich in whole grains, fruits, and vegetables.