Q: Which of the following second-degree heart block is more common with digoxin toxicity? (select one)
A) Mobitz type I (Wenckebach)
B) Mobitz type II
Answer: A
Most of the patients on dig therapy have some degree of first-degree AV block with PR lengthening. One of the earliest signs of excessive serum digoxin is a more marked widening of the PR interval to above 0.2 sec. Second-degree block of the Mobitz type I (Wenckebach) is a sign of dig toxicity in these patients. Mobitz type II block rarely occurs only due to dig. toxicity.
#cardiology
References:
1. Djohan AH, Sia CH, Singh D, Lin W, Kong WK, Poh KK. A myriad of electrocardiographic findings associated with digoxin use. Singapore Med J. 2020 Jan;61(1):9-14. doi: 10.11622/smedj.2020005. PMID: 32043160; PMCID: PMC7900815.
2. Hornestam B, Held P, Edvardsson N. Effects of digoxin on electrocardiogram in patients with acute atrial fibrillation--a randomized, placebo-controlled study. Digitalis in Acute Atrial Fibrillation (DAAF) Trial Group. Clin Cardiol. 1999 Feb;22(2):96-102. doi: 10.1002/clc.4960220208. PMID: 10068846; PMCID: PMC6656138.
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