Patologi Aritmia | Mekanisme Dasar Aritmia - Takikardia dan Bradikardia

Summary

This video explains the mechanisms behind bradycardia and tachycardia (and their arrhythmias). Bradycardia is caused by reduced automaticity in the heart's pacemaker (sinus node) or conduction blocks, often due to increased vagal tone, which can be seen in athletes or during sleep. Tachycardia arises from abnormal impulse formations, such as increased automaticity, triggered activity, and re-entry. The video covers how these issues disrupt the normal heart rhythm, leading to abnormal heart rates and arrhythmias, and emphasizes the importance of understanding these underlying causes in diagnosing and treating heart conditions.

Takeaways

• 😀 The sinus node is the heart's natural pacemaker, controlling the heart's rhythm within a normal range of 60-100 beats per minute.
• 😀 Bradycardia is when the heart rate is below 60 beats per minute, often caused by increased parasympathetic activity or vagus nerve stimulation.
• 😀 Tachycardia is when the heart rate exceeds 100 beats per minute, which can be caused by abnormal impulse formation or re-entry mechanisms.
• 😀 Bradycardia can be physiological, occurring in athletes or during sleep, where the vagus nerve slows the heart rate.
• 😀 When bradycardia occurs due to a reduction in automaticity, it is often linked to an increase in vagus nerve stimulation.
• 😀 Certain diseases and medications can also reduce the heart's automaticity, leading to bradycardia.
• 😀 Another cause of bradycardia is conduction block, which can happen at various points in the heart's conduction system, such as the AV node or His bundle.
• 😀 Tachycardia can result from an abnormal formation of impulses, such as increased automaticity or trigger activity.
• 😀 Trigger activity involves abnormal action potentials, which can initiate arrhythmias if they occur at the wrong time in the cardiac cycle.
• 😀 Re-entry is a major cause of tachycardia, where impulses loop through the conduction pathways, causing rapid, continuous heartbeats.

Q & A

What is the role of the sinus node in heart rhythm?

The sinus node acts as the natural pacemaker of the heart, regulating the heart rate to maintain a normal rhythm, typically between 60-100 beats per minute.

What condition is referred to when the heart rate is below 60 beats per minute?

A heart rate below 60 beats per minute is referred to as bradycardia.

What is bradycardia and what causes it?

Bradycardia is a condition where the heart rate is slower than normal. It can be caused by decreased automaticity of the sinus node or by conduction blocks in the heart's electrical pathways.

How does the vagus nerve affect heart rate?

The vagus nerve, part of the parasympathetic nervous system, can slow down the heart rate by influencing the sinus node, especially in situations like sleep or in athletes due to regular physical training.

What is the physiological significance of bradycardia?

Bradycardia can be a normal physiological response, such as in athletes with a lower resting heart rate due to improved cardiovascular efficiency or during sleep due to increased vagus nerve activity.

What are the causes of tachycardia?

Tachycardia (fast heart rate) can be caused by increased automaticity of the heart’s pacemakers, trigger activity from abnormal action potentials, or a re-entry mechanism where electrical impulses circle through the heart continuously.

What is the mechanism of increased automaticity in tachycardia?

In tachycardia, increased automaticity refers to an abnormal increase in the ability of the heart's pacemaker cells to generate electrical impulses. This can occur due to increased sympathetic nervous system activity or ectopic pacemakers outside of the sinus node.

What is 'trigger activity' in the context of tachycardia?

Trigger activity refers to abnormal action potentials in heart cells that occur during the repolarization phase of the action potential, which can lead to arrhythmias like tachycardia.

Can bradycardia ever be considered normal, and in what situations?

Yes, bradycardia can be normal, particularly in athletes due to their training, which enhances vagus nerve activity, or during sleep when vagus nerve stimulation naturally slows the heart rate.

What is the 're-entry' mechanism in tachycardia?

The re-entry mechanism occurs when electrical impulses continue to circulate through the heart, creating a loop that perpetuates rapid heart rhythm, leading to tachycardia.