Talk:Puzzle 2008 04 014 Answer

the discussant states that the second ECG (1b i think) is a ventricular rhythm, but then goes on to state that the second ECG shows bifascicular block (LAFB+RBBB). the latter diagnosis can not be made in a ventricular rhythm since the his pukinje system is in no way involved with producing an ectopic ventricular (escape) rhythm and hence cannot be detected in a ventricular rhythm. either he/she is wrong about the second ecg being a ventricular escape rhythm or he/she is wrong about the diagnoses of acquired LAFB and RBBB. I suspect the former is the case and the second ECG is in fact a JUNCTIONAL escape rhythm, widened by ischeamic bifasicular block

Response from the author (Verouden)

With interest I read the comment of the ecgpedia visitor on our previously published rhythm puzzle. First, it is important to state that in our answer to the puzzle, we say that figure 1B shows a combined right bundle branch and left anterior fascicular block configuration. This statement does not include an explanation for this configuration. Furthermore, the ECG as depicted in figure 1B shows a regular rhythm of nearly 100 bpm, which makes a junctional escape rhythm, as stated by the visitor, unlikely. An accelerated idioventricular rhythm (AIVR) is frequently observed in the setting of acute myocardial infarction. It is usually a broad complex rhythm at a frequency of 60-120 bpm originating from the ventricular myocardium. If AIVR originates nearby the left posterior fascicle of the left bundle, this will result in ventricular conduction and activation with a likely configuration as shown in figure 1B.