What Second Degree AV Block Type 1 (Wenckebach) Looks Like on Your Watch ECG

Second-degree type 1 or Wenckebach is characterized by a gradual prolongation of the PR interval over a few heart cycles until an atrial impulse (P-wave) is completely blocked, which manifests on the ECG as a P-wave not followed by a QRS complex.

How to Spot Second Degree AV Block Type 1 (Wenckebach) on Your Watch ECG

In second-degree AV block type 1, the sinus node is healthy and fires right on time, so the P waves come at regular intervals. However, atrial impulses traveling through the AV node take longer and longer to conduct at each subsequent impulse, causing a progressive prolongation of the PR interval until one impulse is completely blocked. As a result, QRS complexes are periodically dropped, resulting in a slowed heart rhythm (bradycardia), with more P waves than QRS complexes on the ECG.

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These are the defining characteristics of second-degree AV block type 1:

• Rhythm: Irregular
• P wave: Normal
• P-R interval: Progressively longer until a QRS complex is missed, then cycle repeats
• QRS: Normal or Narrow

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Common Symptoms of Second Degree AV Block Type 1 (Wenckebach)

Most people with second-degree AV block type 1 do not present any symptoms. Some individuals may occasionally feel:

• Light-headedness
• Dizziness
• Fatigue

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More rarely, second-degree AV block type 1 may lead to a sudden and temporary loss of consciousness, also known as syncope, caused by a brief decrease in the oxygen supply to the brain.

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Any Cause for Concern?

Second-degree AV block type 1 (Wenckebach) is often a benign condition that does not usually progress to more severe types of heart block. However, in some people, it may cause symptoms or indicate that a person has an underlying medical condition.

As always, if you show signs of a potential second-degree AV block type 1, contact your healthcare provider as soon as possible to rule out the presence of harmful underlying conditions.

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Still Not Sure How to Spot Second Degree AV Block Type 1 (Wenckebach) on Your Watch ECG?

Your smartwatch can be your partner in looking after your heart. If you’re concerned about second-degree AV block type 1 (Wenckebach), get your smartwatch ECGs analyzed by experts within minutes on the QALY app: iOS and Android.

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