Second Degree AV Block: What You Need To Know

If you’re a medical professional, then you know that second degree AV block is a heart problem that can be difficult to diagnose and treat. It can be caused by a variety of factors, but it often goes unnoticed until it has progressed to an advanced stage. That’s why it’s important for healthcare professionals to understand the signs, symptoms and treatments associated with this condition. In this blog post, we will explore what second degree AV block is and how medical professionals can recognize and treat it. 

Second Degree AV Block:

Second degree AV block is a condition in which there is a delay in the conduction of electrical impulses from the atria to the ventricles. This can cause the heart to beat too slowly or irregularly. In some cases, second degree AV block can lead to life-threatening arrhythmias. There are two types of second degree AV block: Type I and Type II. Type I second degree AV block is also called Mobitz I or Wenckebach block. In this type, there is a progressive delay in the conduction of electrical impulses from the atria to the ventricles. The heart rate will slow down until there is a pause in the heartbeat. This pause is called an AV nodal escape beat. Type II second degree AV block is also called Mobitz II block. In this type, there is a sudden, complete blockage of electrical impulses from the atria to the ventricles. This can cause the heart to beat very slowly or stop altogether. Second degree AV block can be caused by a variety of factors, including coronary artery disease, hypertension, diabetes, and certain medications. It can also be seen in healthy people who have no other underlying heart conditions.

Symptoms of Second Degree AV Block

When a patient has second degree AV block, there are usually no symptoms. However, if the block is incomplete, the patient may experience occasional skipped beats or an irregular heartbeat. If the block is more complete, the patient may experience lightheadedness, dizziness, or fainting. In severe cases, the patient may experience chest pain or shortness of breath.

Causes of Second Degree AV Block

Second degree AV block occurs when the conduction of electrical impulses from the atria to the ventricles is delayed. This can be caused by a variety of factors, including:

-Diseases that affect the conduction system of the heart, such as cardiomyopathy or heart defects
-Inflammation or scarring of the conduction system, as can occur with viral myocarditis
-Use of certain medications that slow down heart rate, such as beta blockers or calcium channel blockers
-Electrolyte imbalances, such as low potassium levels

Treatment of Second Degree AV Block

There are two types of second degree AV block, Mobitz I and Mobitz II. Treatment for each is different, so it’s important to know which type you or your patient has. Mobitz I second degree AV block is also called Wenckebach block. With this type, the PR interval lengthens until a P wave is not followed by a QRS complex. This happens because the conduction time from the atria to the ventricles becomes longer than the refractory period of the AV node. Usually, no treatment is necessary for Mobitz I block. If there are symptoms, such as fatigue or dizziness, beta blockers can be used to slow the heart rate and alleviate symptoms. Mobitz II second degree AV block is less common than Mobitz I. With this type, some P waves are conducted to the ventricles, but others are not. The QRS complexes may be normal or wide (over 0.12 seconds). This happens because the conduction system below the AV node is damaged. Treatment for Mobitz II second degree AV block usually involves a pacemaker, which helps to regulate the heart rate and prevent bradycardia-related symptoms.

Prognosis of Second Degree AV Block

-Third degree AV block: This is a more serious form of AV block where the heart's electrical signals are completely blocked. This can lead to serious consequences including cardiac arrest. 

-Heart failure: If the heart is not able to pump blood effectively, this can lead to heart failure. 

-Stroke: If the blood supply to the brain is interrupted, this can lead to a stroke.

Conclusion

Second degree AV block is a type of conduction disorder that affects the impulses from the atria to the ventricles, leading to an irregular heart rate. By understanding its causes and recognizing its symptoms, medical professionals can help diagnose and treat second-degree AV block in patients.

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