Bradycardia is a medical condition characterized by an abnormally slow heart rate, typically less than 60 beats per minute. In some cases, bradycardia may be normal, such as during sleep or in highly trained athletes who have developed a lower resting heart rate. However, in many cases, it can indicate an underlying medical problem, such as damage to the heart’s electrical system, hypothyroidism, or medication side effects. Symptoms of bradycardia can include fatigue, dizziness, fainting, and shortness of breath.

Fig 27 brady
There are several different types of bradycardia, which can be classified based on the location of the problem within the heart’s electrical system or the underlying cause of the condition. Here are some of the most common types of bradycardia:
  • heartbeat1

    Sinus node dysfunction, or sick sinus node syndrome, refers to a condition in which the sinoatrial (SA) node, the natural pacemaker of the heart, does not function properly. The SA node is responsible for generating electrical impulses that stimulate the heart to contract and pump blood throughout the body. Sinus node dysfunction can occur when the SA node fails to generate impulses, generates them too slowly, or generates them in an irregular pattern. This can result in bradycardia.

  • heartbeat1

    AV node dysfunction refers to a condition in which the atrioventricular (AV) node, a cluster of cells in the heart that regulates the flow of electrical impulses between the upper and lower chambers of the heart, does not function properly. AV node dysfunction can occur when the AV node delays the impulses, or blocks some of the impulses from reaching the ventricles. This can result in a condition called heart block of which there are different degrees of heart block, ranging from mild to severe.

  • heartbeat1

    Medication-induced bradycardia: Certain medications, such as beta-blockers or calcium channel blockers, can slow down the heart rate.

Fig 1 the cardiac conduction system Converted 1

If the bradycardia is mild and does not cause any symptoms, treatment may not be necessary. However, if the bradycardia is causing symptoms such as dizziness, fainting, fatigue, or shortness of breath, medical intervention may be required.

Fig 23 Brady Converted

If bradycardia is caused by an obvious treatable cause, then correcting that factor maybe all what is needed. For example, stopping beta-blockers or calcium channel blockers, or treating hypothyroidism may help to increase the heart rate and improve symptoms.

Fig 25 pacemaker

For persistent bradycardia, the most common treatment is a pacemaker. A pacemaker is a small device that is implanted under the skin of the chest and connected to the heart with wires. The pacemaker generates electrical impulses to regulate the heart rate and maintain a normal rhythm. There are different types of pacemakers that can be programmed to meet individual needs. It is important to consult with an electrophysiologist if you have significant bradycardia in order to decide of a pacemaker is indicated or not and the type of pacemaker to be implanted if deemed necessary.