What are those intermittent "S" waves?

A 69-year-old woman had three syncopal events while flying on an airplane. She was found to be profoundly bradycardic. Two 12­lead electrocardiograms (ECGs) showed ventricular rates in the thirties. In one, the QRS complexes were narrow. In the second ECG, there were wide negative deflections following the QRS complexes. Analysis of telemetry recordings revealed the underlying mechanism and helped establish appropriate programing of an implanted pacemaker.

Common ECG interpretation software mistakes Part III: Computer errors that should never be missed.

Electrocardiogram interpretation software mistakes can lead to incorrect diagnoses and inappropriate treatments. Occasionally, the consequences of not recognizing such mistakes are disastrous. This final chapter on software mistakes describes three relatively common computer errors that should never be missed because not recognizing them can result in stroke, cardiac arrest, and even death. In each of the scenarios covered, we describe the clinical background, and provide simple recommendations on how such mistakes can be easily identified and corrected.

Common ECG interpretation software mistakes Part II: Computer errors that hide diagnostic clues.

Electrocardiogram (ECG) interpretation software mistakes can lead to incorrect diagnoses and inappropriate treatments. Occasionally, however, repetitive and consistent computer errors may hide important clues for correct diagnoses that otherwise could have been missed. We present a collection of a few common and clinically important such peculiarities, and provide tools on how to prove or disprove the suspected diagnosis. In addition to the illustrations in print, an online supplement (OS) shows more examples of the discussed phenomena. In each ECG, the original computer interpretations were enlarged for legibility.

Common ECG interpretation software mistakes. Part I: False reporting of myocardial infarction.

The purpose of computerized analysis of electrocardiograms (ECGs) is to provide rapid interpretation in places where ECG experts are not available, and to save physician time for all providers. For the most part, contemporary interpretation algorithms perform remarkably well and offer correct diagnoses of common ECG abnormalities. Diagnostic accuracy for myocardial ischemia and infarction is reasonably good but with these conditions, false positive and false negative readings can be disastrous. It is essential, therefore, that computerized statements be over-read by trained physicians. A three-part mini-series is intended to provide assistance to quickly recognize and correct common interpretation software mistakes. This first chapter presents interpretation errors that falsely indicate myocardial infarction.

Computer-Estimated Heart Rate vs True Heart Rate-Be Aware of the Software.

This case report describes a patient in their 60s with gastrointestinal bleeding and shock with heart rate overcounting by software indicating severe hyperkalemia.

Electrocardiographic Risk Factors for a Common Cardiac Condition.

This case report describes a patient in their 60s with a history of several months of recurrent dizziness and occasional palpitation who presented to the emergency department after an episode of syncope.

Precordial ST-segment continuum: A variant of the de Winter sign.

The vast majority of patients with acute occlusion of the proximal left anterior descending coronary artery (LAD) suffer frank ST-elevation myocardial infarction (STEMI). In contrast, a small but not insignificant minority presents with an electrocardiographic (ECG) pattern termed the "de Winter sign." The de Winter sign is characterized by upsloping ST depression followed by tall and peaked T waves in the precordial leads. The purpose of this report is to present two cases of acute obstruction of a large wrap-around LAD where the ECGs simultaneously displayed diagnostic criteria both for STEMI and the de Winter sign. We provide possible explanations for this hitherto undescribed phenomenon.