Ventricular beat detection in single channel electrocardiograms

BACKGROUND: Detection of QRS complexes and other types of ventricular beats is a basic component of ECG analysis. Many algorithms have been proposed and used because of the waves' shape diversity. Detection in a single channel ECG is important for several applications, such as in defibrillators and specialized monitors. METHODS: The developed heuristic algorithm for ventricular beat detection includes two main criteria. The first of them is based on steep edges and sharp peaks evaluation and classifies normal QRS complexes in real time. The second criterion identifies ectopic beats by occurrence of biphasic wave. It is modified to work with a delay of one RR interval in case of long RR intervals. Other algorithm branches classify already detected QRS complexes as ectopic beats if a set of wave parameters is encountered or the ratio of latest two RR intervals RR(i-1)/RR(i )is less than 1:2.5. RESULTS: The algorithm was tested with the AHA and MIT-BIH databases. A sensitivity of 99.04% and a specificity of 99.62% were obtained in detection of 542014 beats. CONCLUSION: The algorithm copes successfully with different complicated cases of single channel ventricular beat detection. It is aimed to simulate to some extent the experience of the cardiologist, rather than to rely on mathematical approaches adopted from the theory of signal analysis. The algorithm is open to improvement, especially in the part concerning the discrimination between normal QRS complexes and ectopic beats

The standard 11-lead ECG. Neglect of lead aVR in the classical limb lead display

This study investigates how the format of limb lead display influences electrocardiographic (ECG) interpretation. The positive aspect of lead aVR (included in the classical display) is directed opposite to that of the other leads. This could lead to an ECG interpreter's disregard of lead aVR, thus providing a "standard 11-lead ECG." It is hypothesized that when using the classical limb lead display, ECG interpreters often ignore lead aVR, even when considering complex ECGs. Thirty-five of the participants attending this International Society of Computerized Electrocardiology meeting were asked to interpret five complex ECGs, displayed in the classical format. Lead aVR had been replaced by lead -aVR on all of these recordings. Second, the participants were asked if they (1) used all 12 leads, (2) used lead aVR, and (3) noticed that lead aVR had been changed. The results indicate that a vast majority of interpreters (80-94%) did not detect when lead aVR had been reversed. This suggests that interpreters only use 11 of the standard leads when presented with the classical display method to evaluate clinical problems

Vectorcardiogram more sensitive than 12‐lead ECG in the detection of inferior myocardial infarction

Summary. The vectorcardiogram (VCG) is commonly stated to be more sensitive than the 12‐lead electrocardiogram (ECG) for the diagnosis of inferior myocardial infarction. However, a recent study indicated that VCG is not superior to ECG for this diagnosis. The purpose of this study was to compare the performance of VCG and ECG criteria and to indicate possible explanations for the disagreement between earlier studies. Accordingly, we studied 65 patients with inferior myocardial infarction verified by left ventriculography or 201‐TI myocardial scintigraphy and 351 normal subjects. Sensitivity was 69% (45/65) and 43% (28/65) for the VCG and ECG criteria, respectively. This difference was highly significant (P<0·001). Among the normal subjects there were only three with false positive VCG and none with false positive ECG. We conclude that both VCG and ECG criteria for the diagnosis of inferior myocardial infarction are highly specific and that VCG criteria have greater sensitivity than ECG criteria

Why complicate an important task? An orderly display of the limb leads in the 12-lead electrocardiogram and its implications for recognition of acute coronary syndrome

Background: In the standard ECG display, limb leads are presented in a non-anatomical sequence: I, II, III, aVR, aVL, aVF. The Cabrera system is a display format which instead presents the limb leads in a cranial/left-to-caudal/right sequence, i.e. in an anatomically sequential order. Lead aVR is replaced in the Cabrera display by its inverted version, -aVR, which is presented in its logical place between lead I and lead II. Main text: In this debate article possible implications of using the Cabrera display, instead of the standard, non-contiguous lead display, are presented, focusing on its use in patients with possible acute coronary syndrome. The importance of appreciating reciprocal limb-lead ECG changes and the diagnostic and prognostic value of including aVR or lead -aVR in ECG interpretation in acute coronary syndrome is covered. Illustrative cases and ECGs are presented with both the standard and contiguous limb lead display for each ECG. A contiguous lead display is useful when diagnosing acute coronary syndrome in at least 3 ways: 1) when contiguous leads are present adjacent to each other, identification of ST elevation in two contiguous leads is simple; 2) a contiguous lead display facilitates understanding of lead relationships as well as reciprocal changes; 3) it makes the common neglect of lead aVR unlikely. Conlusions: It is logical to display the limb leads in their sequential anatomical order and it may have advantages both in diagnostics and ECG learning

Dr. Galen Wagner (1939-2016) as an Academic Writer: An Overview of his Peer-reviewed Scientific Publications

Cardiolog