Arrhythmias

The causes depend on the type of arrhythmia. The bradyarrhythmia may be due to problem in the sinoatrial (SA) node. SA nodal dysfunction may be classified as intrinsic or extrinsic. If it is extrinsic, then the same should be corrected before considering pacemaker therapy. Drugs and autonomic nervous system problems can lead to extrinsic SA nodal dysfunction. Other reasons are 

• Hypothyroidism, 
• Sleep apnea, and 
• Conditions mostly encountered in critically ill patients like 
• Hypothermia, 
• Hypoxia, 
• Increased intracranial pressure, etc. 

If the bradyarrhythmia is caused by problems in the atrioventricular (AV) node, then the following reasons might be responsible:

• Metabolic or endocrine problems like hyperkalemia, hypermagnesemia, hypothyroidism and adrenal insufficiency
• Drug related problems like the use of beta-blockers, calcium channel blockers, digitalis, adenosine, antiarrhythmics and lithium
• Infectious causes like endocarditis, Lyme disease, Chagas’ disease, syphilis, tuberculosis, diphtheria and toxoplasmosis
• Heritable or congenital problems
• Inflammatory diseases 
• Coronary artery disease

The main types of arrhythmias encountered in clinical practice are:

• Sinoatrial (SA) node bradyarrhythmia
• Atrioventricular (AV) node bradyarrhythmia
• Supraventricular tachyarrhythmia
• Paroxysmal supraventricular tachycardia
• Sinus tachycardia

Pharmacologic therapy includes the use of drugs like beta-blockers or calcium channel blockers. Also antiarrhythmic drugs of class I and III also promote SA node exit block. If the drugs don’t work, then the doctor may take a decision to implant a pacemaker.

Drugs such as beta-blockers or calcium channel blockers can be used. Also antiarrhythmic drugs of class I and III also promote SA node exit block. Isoproterenol or atropine administration administered intravenously may increase sinus rate acutely.

An artificial pacemaker can correct an abnormal low heart rate caused by SA node failure or heart block. Such an implanted device rhythmically generates impulses that spread throughout the heart to drive both the atria and the ventricles at the typical rate of 70 beats per minute. 

The different types of pacemakers that are available are:

• Single chamber pacemaker which usually carries impulses to the right ventricle of the heart
  
  
• Dual chamber pacemaker that carries impulses to the right ventricle and the right atrium of the heart. It controls the timing of contractions between two chambers.
  
  
• Biventricular pacemaker involves biventricular pacing which is also known as cardiac resynchronization therapy. It is for people who have heart failure due to abnormal electrical systems. This type of pacemaker stimulates both the ventricles for efficient beating of the heart.

Usually the battery in the pacemaker lasts an average of 15 years. When it wears out, the pacemaker’s pulse generator is replaced.

The surgery of the pacemaker carries some complications like infection at the site of the surgery or swelling, bruising or bleeding at the generator site especially if the patient takes blood-thinning medications. The other complications may include damage to the adjoining nerves and blood vessels and collapsed lung. 

• Cell phones need to be kept at least 6 inches away from the pacemaker
• Passing through the airport security systems can sound the alarm but doesn’t cause any harm.
• It is necessary to inform medical professionals about the pacemaker. Certain procedures and surgeries can interfere with the pacemaker. These include imaging techniques like MRI and CT scans; cancer radiation treatment; electrocautery to control bleeding during surgery; and shock-wave lithotripsy to break up large kidney stones or gallstones.