Don't jump to conclusion yet

This patient was admitted due to dizziness.

Image 1

This second degree AV block 2:1 (Image 1) . A 2:1 second degree AV block is a subtype of second degree AV block. It can either be due to a Mobitz I (aka Wenckebach) or Mobitz II. A long strip will resolve the issue. Most authors will say that if the PRI is normal with an a wide QRS then it is most likely type II and it could be type I if the PRI is prolonged and normal QRS.

Image 2

This is from the same patient (Image 2) . There are dropped P waves. There are PRI changes prior to the dropped P. This sinus tachycardia, second degree AV block type II (Mobitz II) with right bundle branch block (RBBB) and left anterior fascicular block (LAFB) pattern. So, the 2:1 was due to a Mobitz II mechanism.

A pacemaker was eventually inserted.

#584

Mobitz II with Very Long PRI

A 70 yo with h/o of HTN, DM and CAD admitted due to dizziness

Figure 1 - ECG case

2:1 AV block - A subtype of Second degree AV block

Figure 1

Sinus rhythm, 2:1 AV block due to Mobitz II

This is a 70 yo pt who was admitted due to weakness. What is your interpretation?

Figure 1 - ECG case

Sinus rhythm, 2:1 AV block due to Mobitz II

Figure 2 - case marked

The sinus (atrial) rate is about 88 bpm and the ventricular rate is about  42 bpm. The QRS has right bundle branch block (RBBB) configuration. There are 2 P's for every 1 QRS. This is termed 2:1 AV block. A 2:1 AV block is a special form of second degree AV block. It can either be second degee type I (Mobitz I or Wenckebach) or second degree type II (Mobitz II). A longer strip is needed to elucidate the mechanism. In this case, this 10 second strip captured 3:2 AV conduction showing a dropped beat with no PR interval prolongation prior to the dropped beat. So, this is second degree AV block type II (Mobitz II) manifesting as 2:1 (predominantly) and 3:2 AV conduction.

Sinus rhythm, advanced heart block

Figure 3 - Advanced Heart Block

This 10 sec strips is minutres after the previous strip. QRS #2 is a conducted beat and after that there is AV dissociation due to accelerated idioventricular rhythm (AIVR). Obvious P waves are marked in read and hidden P waves are marked in green. When the AV conduction ratio s 3:1 or higher, the rhythm is called advanced AV block. This block occurs because of AV node or His-purkijne disease and not retrograde concealment in the AV node or His-Purkije system caused by junctional or ventricular escape complexes. A few minutes later, 2:1 AV blocked recurred (not shown). A permanent pacemaker was eventually placed.

Reference:

Surawicz B and Knilans TK. 2008. Chou’s Electrocardiography in Clinical Practice. 6th ed. PA. Saunders-Elseiver

Issa Z, Miller J and Zipes D. 2012. Clinical Arrhythmology and Electrophysiology A Companion to Braunwald’s Heart Disease 2nd Ed. PA Saunders

Das and Zipes. 2012. Electrocardiography of arrhythmias : a comprehensive review. Elsevier PA

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