2nd Degree AV Block Type 2, ECG/EKG, Symptoms, Treatment, Strip, vs Type 1, Sinus Rhythm

Content:

What is 2nd Degree AV Block Type 2?
2nd Degree AV Block Type 2 ECG/EKG
2nd Degree AV Block Type 2 Symptoms
2nd Degree AV Block Type 2 Treatment
2nd Degree AV Block Type 2 Strip
2nd Degree AV Block Type 2 vs Type 1
2nd Degree AV Block Type 2 Sinus Rhythm

What is 2nd Degree AV Block Type 2?

2nd Degree AV Block Type 2, also known as Mobitz Type II, is a cardiac conduction abnormality in which some atrial impulses fail to reach the ventricles. This occurs unpredictably, without progressive PR interval prolongation. It indicates a problem in the His-Purkinje system and often signals a serious conduction disorder.

Because of its potential to progress to complete heart block, Type 2 AV block is considered more dangerous than Type 1 and requires careful monitoring and often urgent intervention.

2nd Degree AV Block Type 2 ECG/EKG

On an ECG, 2nd Degree AV Block Type 2 presents with intermittent non-conducted P waves. The PR interval remains constant for conducted beats, but some P waves are suddenly not followed by QRS complexes. This "dropped beat" is a hallmark of the condition.

The regularity of the PR intervals in conducted beats differentiates it from Type 1, where PR progressively lengthens. Type 2 often occurs with a fixed conduction ratio such as 2:1 or 3:1 (two or three P waves per one QRS).

EKG findings reinforce the pattern of a regular PR interval with sudden dropped QRS complexes. The P waves are typically regular, but some do not produce a ventricular response. The QRS complex may be widened if the block is infranodal.

These EKG features should prompt evaluation for underlying cardiac disease and consideration for pacemaker placement, as this type of block is typically not transient.

2nd Degree AV Block Type 2 Symptoms

Symptoms can vary but often include:

Dizziness or lightheadedness
Syncope (fainting)
Fatigue
Palpitations
Bradycardia (slow heart rate)

Because the condition can progress rapidly to complete heart block, these symptoms are considered warning signs and should not be ignored.

2nd Degree AV Block Type 2 Treatment

Treatment typically involves permanent pacemaker implantation. Since Type 2 is associated with high risk of progression and unstable rhythms, temporary pacing may also be needed in emergencies.

Medications are generally not effective and are rarely used alone. Addressing any reversible causes, such as medication-induced AV block, is also important as part of management.

2nd Degree AV Block Type 2 Strip

An ECG strip for Type 2 block will show a pattern of conducted and non-conducted P waves with fixed PR intervals. The sudden absence of QRS after a normal P wave is the critical finding. This is best observed in a rhythm strip over a 6–10 second duration for pattern recognition.

Strip analysis is essential for diagnosis and differentiating it from other arrhythmias or conduction issues like Type 1 or complete block.

2nd Degree AV Block Type 2 vs Type 1

The key difference between Type 2 and Type 1 AV block lies in the PR interval behavior and risk level. In Type 1 (Mobitz I), the PR interval gradually lengthens until a QRS is dropped. In Type 2, the PR interval remains constant, but QRS complexes are suddenly absent.

Type 2 is more clinically serious, with a higher chance of complete AV block and requiring pacemaker intervention. Type 1 is often benign and may not need treatment unless symptomatic.

2nd Degree AV Block Type 2 Sinus Rhythm

2nd Degree AV Block Type 2 can occur alongside normal sinus rhythm, where the SA node fires regularly, producing consistent P waves. However, the AV node or below fails intermittently, leading to dropped QRS complexes.

This means the rhythm is "sinus with 2nd Degree AV Block Type 2," where the atrial rhythm is maintained, but ventricular response is irregular. It’s essential to identify this on ECG to guide urgent management.