Heart Education
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What Second-Degree AV Block Type 2 Looks Like on Your Watch ECG

QALY Team
Second-degree AV Block Type 2 on smartwatch ECG (Apple Watch, Kardia, Samsung, Fitbit)

Key Takeaways

Second-degree AV block type 2 is a disorder of the heart's electrical conduction system. It is a conduction block between the atria and ventricles. The electrical activity from your heart’s upper chamber (atria) passing through the AV node slows down or gets interrupted on its way to the heart’s lower chamber (ventricles), and there is no QRS complex to follow in that instance.

How to Spot Second-Degree AV Block Type 2 on Your Watch ECG

In second-degree AV block type 2, P waves are blocked relatively randomly, and they are not preceded by prolongation of the PR interval. Instead, the PR interval in conducted beats remains constant, and P waves appear to march through at a constant rate.

The following characteristics can help you spot this rhythm:

  • Non-conducted P-waves (P-waves with no QRS complexes)
  • P-waves are normal, but more P waves than QRS complexes.
  • PR interval is constant and can be normal or prolonged.
  • Narrow QRS, when the heart block is within a part of the heart called the “Bundle of His.”
  • Wide QRS, when the heart block is away from a part of the heart called the “Bundle of His.” This is the more likely case.

Example of Second-Degree AV Block Type 2 caught with Apple Watch
Example of Second-Degree AV Block Type 2 caught with Apple Watch

Common Symptoms of Second-Degree AV Block Type 2

People with second-degree AV block type 2 experience symptoms related to decreased cardiac output, including fatigue, dyspnea, and chest pain, though the severity can vary between individuals.

If many impulses are blocked at a time, cardiac output can be severely reduced, resulting in hypotension, bradycardia, and hemodynamic instability. The onset of hemodynamic instability may be sudden and unexpected, leaving individuals at a higher risk of syncope or sudden cardiac arrest.

Treatment begins by addressing any potentially reversible causes of a nodal block, including:

  • medications that can slow nodal conduction (e.g., digoxin, beta-adrenergic blockers, calcium-channel blockers, amiodarone)
  • treating electrolyte imbalances, like hyperkalemia.
  • addressing the specific underlying cause when possible.

Since second-degree AV block type 2 has a high risk of progressing into a 3rd degree AV block, treatment typically involves the insertion of a permanent pacemaker.

Any Cause for Concern?

Second-degree AV block type 2 is rarely seen in individuals without underlying structural heart disease. However, it has a high rate of progression to third-degree heart block. As always, if you show signs of potential second-degree AV block type 2, contact your healthcare provider as soon as possible to rule out the presence of harmful underlying conditions.

Still Not Sure How to Spot Second-Degree AV Block Type 2 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 2, get your smartwatch ECGs analyzed by experts within minutes on the QALY app: iOS and Android.

Get second opinions of your ECGs by human experts on the QALY app!

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