![]() ![]() Having a prior ECG for comparison would also be invaluable for determining if the ST elevation seen here is new or old. Our clinical interpretation would vary dramatically based on answers to these questions. We are literally lost without it - as we have no idea if the patient in question was having new-onset crushing chest pain, having pleuritic-type chest pain with pericardial friction rub on exam - or was entirely asymptomatic. This case also illustrates the tremendous importance of knowing the history.That said - computerized ECG interpretations can have utility IF used correctly ( Click HERE for a link to download our pdf Review on " Optimal Use of Computerized ECG Interpretations" ). Computerized ECG Interpretations are not always correct ( and this case is a glaring example of how they can go wrong ). ![]() This accounts for why beat #3 is sinus-conducted ( with a normal PR interval) - whereas slightly earlier occurring beat #7 is a junctional escape beat ( that occurs just before the P wave preceding it is able to conduct to the ventricles ). Finally - is the subtle finding that the escape interval preceding beat #3 (ie, the distance between beats #2-3 ) is slight longer than the distance between beats #6-7.Normal sinus rhythm then resumes with beat #8. The reason the PR interval preceding beat #7 is shorter - is that beat #7 is a junctional escape beat that occurs just before before the P wave that precedes it is able to conduct to the ventricles. The occurrence of a PAC resets the sinus cycle, usually with a brief pause after the early beat.A similar very early-occurring PAC ( corresponding to a PAC at point B in Figure 2 can be seen notching the T wave of beat #2 ). The cause of the pause in this case is a blocked PAC ( arrow in the T wave of beat #6 highlights the "telltale notching" of a PAC buried in this T wave ). ![]()
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