Deeply Inverted and Biphasic T-Waves of Wellens' Syndrome: A Characteristic Electrocardiographic Pattern Not To Forget

Wellens’ syndrome refers to specific electrocardiographic (ECG) abnormalities of deeply inverted T-waves in the precordial leads, mainly V1-V3, associated with critical stenosis of the proximal left anterior descending (LAD) coronary artery. Identifying this specific pattern on the electrocardiogram is important as emergent treatment can prevent life-threatening myocardial infarction. We present a case of Wellens’ syndrome that had a combination of inverted and biphasic T-waves patterns and where timely identification of the abnormal ECG pattern by the emergency physician and prompt intervention by the cardiology team prevented the development of myocardial infarction and hence permanent damage to the heart.

Sequence to Sequence ECG Cardiac Rhythm Classification Using Convolutional Recurrent Neural Networks

This paper proposes a novel deep learning architecture involving combinations of Convolutional Neural Networks (CNN) layers and Recurrent neural networks (RNN) layers that can be used to perform segmentation and classification of 5 cardiac rhythms based on ECG recordings. The algorithm is developed in a sequence to sequence setting where the input is a sequence of five second ECG signal sliding windows and the output is a sequence of cardiac rhythm labels. The novel architecture processes as input both the spectrograms of the ECG signal as well as the heartbeats' signal waveform. Additionally, we are able to train the model in the presence of label noise. The model's performance and generalizability is verified on an external database different from the one we used to train. Experimental result shows this approach can achieve an average F1 scores of 0.89 (averaged across 5 classes). The proposed model also achieves comparable classification performance to existing state-of-the-art approach with considerably less number of training parameters.

A Silent Killer: Left Main Coronary Artery Disease in Gastrointestinal Bleed

Left main coronary artery disease (LMCAD) is defined as more than 50% angiographic arterial narrowing and has been demonstrated in nearly 5% of all patients undergoing coronary angiography. It carries an extremely high risk for cardiovascular morbidity and mortality as it impacts more than two-thirds of the left ventricle. Prediction of LMCAD in the right clinical setting is important for the selection of the proper treatment strategies. Typical ECG characteristics are ST elevation (STE) in lead augmented vector right (aVR-STE) of more than 0.5 mV accompanied by ST depression (STD) notably in leads I, II, and V4-6 or STE in aVR ≥ V₁. Furthermore, the presence of aVR-STE is associated with worse outcomes and careful evaluation and close monitoring are warranted. However, not every aVR-STE is an acute occlusion of the left main coronary artery (LMCA), as acute occlusion is a catastrophic event. aVR-STE can also be associated with severe triple-vessel disease or diffuse subendocardial ischemia.

Frequency of Left Ventricular Hypertrophy Among Patients on Maintenance Hemodialysis by Voltage Criteria and Its Relationship with Biophysical-Chemical Parameters

Background Among the dialysis population, left ventricular hypertrophy (LVH) is becoming a major cause of cardiovascular death, mainly due to myocardial infarction, heart failure, and arrhythmias. Electrocardiography (ECG) is a cheap and easily available test to detect the presence of left ventricular hypertrophy. The basic purpose of this study was to assess the frequency of left ventricular hypertrophy among the maintenance hemodialysis patients by applying different voltage criteria for the diagnosis of LVH and its relationship with various biophysical and biochemical parameters. Methods A total of 68 patients of end-stage renal disease (ESRD) were included in the study who were on maintenance hemodialysis at the dialysis center of Sughra Shafi Hospital. Baseline characteristics were recorded from the patients' data. Blood samples were drawn and electrocardiographs were taken, both before and after hemodialysis. Results Results showed variability in the detection of left ventricular hypertrophy in the pre- and post-dialysis period, as it was positive for 45%, 21%, and 17% in the pre-dialysis period versus 40%, 32%, and 25% in the post-dialysis period, when the Framingham, Sokolow-Lyon, and Cornell criteria were applied, respectively. The study showed a significant relationship between left ventricular hypertrophy with a high body mass index (BMI), hypertension, and pre- and post-dialysis hypomagnesemia (P <0.05). A significant association was also seen with low serum albumin levels over the past year. Conclusion According to this study, almost half of the dialysis patients were having left ventricle hypertrophy when Framingham criteria were applied. Good control of factors that are significantly associated with the occurrence of left ventricular hypertrophy can reduce morbidity and mortality among dialysis patients secondary to cardiovascular events. In this study, these factors included hypertension, hypomagnesemia, hypoalbuminemia, and high BMI.

Do Electrocardiogram Rhythm Findings Predict Cardiac Activity During a Cardiac Arrest? A Study from the Sonography in Cardiac Arrest and Hypotension in the Emergency Department (SHoC-ED) Investigators

Introduction Electrocardiographic (ECG) rhythms are used during advanced cardiac life support (ACLS) to guide resuscitation management. Survival to hospital discharge has been reported to be better for patients with pulseless electrical activity (PEA) than asystole in out-of-hospital arrests. Despite this, treatment for these two (non-shockable) rhythms is combined in ACLS guidelines. This study examines if the recorded cardiac rhythm of asystole or PEA during ACLS accurately predicts mechanical cardiac activity as determined by point-of-care ultrasound (PoCUS). Methods A database review was completed for patients (> 19 years without a do not resuscitate (DNR) order) who presented to a tertiary emergency department in PEA or asystolic cardiac arrest between 2010 and 2014. Patients were separated into two groups: those with electrical cardiac activity (PEA) and those without (asystole). We compared ECG rhythm and PoCUS-documented cardiac activity results (both initial and any) for each case. Results  A total of 186 patients met the study criteria. The 46 patients with PEA on ECG were more likely to have cardiac activity than the 140 patients with asystole (odds ratio 7.22 (95% confidence intervals 2.79-18.7) for activity on initial PoCUS; odds ratio 5.45 (2.49-12.0) for activity on any PoCUS during arrest). ECG alone was poorly sensitive for initial cardiac activity (63.64%; 40.66% to 82.80%) and any cardiac activity (54.29%; 36.65% to 71.17%), with specificity marginally better at 80.49% (73.59% to 86.25%) for initial and 82.12% (75.06% to 87.87%) for any activity. Conclusion Our results suggest that ECG rhythm alone is not an accurate predictor of cardiac activity. This supports the use of PoCUS during cardiac arrest, in addition to ECG, to identify patients with ongoing mechanical cardiac activity and to help determine appropriate treatment for this group.

Is computer-assisted instruction more effective than other educational methods in achieving ECG competence among medical students and residents? Protocol for a systematic review and meta-analysis

INTRODUCTION

Although ECG interpretation is an essential skill in clinical medicine, medical students and residents often lack ECG competence. Novel teaching methods are increasingly being implemented and investigated to improve ECG training. Computer-assisted instruction is one such method under investigation; however, its efficacy in achieving better ECG competence among medical students and residents remains uncertain.

METHODS AND ANALYSIS

This article describes the protocol for a systematic review and meta-analysis that will compare the effectiveness of computer-assisted instruction with other teaching methods used for the ECG training of medical students and residents. Only studies with a comparative research design will be considered. Articles will be searched for in electronic databases (PubMed, Scopus, Web of Science, Academic Search Premier, CINAHL, PsycINFO, Education Resources Information Center, Africa-Wide Information and Teacher Reference Center). In addition, we will review citation indexes and conduct a grey literature search. Data extraction will be done on articles that met the predefined eligibility criteria. A descriptive analysis of the different teaching modalities will be provided and their educational impact will be assessed in terms of effect size and the modified version of Kirkpatrick framework for the evaluation of educational interventions. This systematic review aims to provide evidence as to whether computer-assisted instruction is an effective teaching modality for ECG training. It is hoped that the information garnered from this systematic review will assist in future curricular development and improve ECG training.

ETHICS AND DISSEMINATION

As this research is a systematic review of published literature, ethical approval is not required. The results will be reported according to the Preferred Reporting Items for Systematic Review and Meta-Analysis statement and will be submitted to a peer-reviewed journal. The protocol and systematic review will be included in a PhD dissertation.

PROSPERO REGISTRATION NUMBER

CRD42017067054; Pre-results.

Breathing Rate Estimation From the Electrocardiogram and Photoplethysmogram: A Review

Breathing rate (BR) is a key physiological parameter used in a range of clinical settings. Despite its diagnostic and prognostic value, it is still widely measured by counting breaths manually. A plethora of algorithms have been proposed to estimate BR from the electrocardiogram (ECG) and pulse oximetry (photoplethysmogram, PPG) signals. These BR algorithms provide opportunity for automated, electronic, and unobtrusive measurement of BR in both healthcare and fitness monitoring. This paper presents a review of the literature on BR estimation from the ECG and PPG. First, the structure of BR algorithms and the mathematical techniques used at each stage are described. Second, the experimental methodologies that have been used to assess the performance of BR algorithms are reviewed, and a methodological framework for the assessment of BR algorithms is presented. Third, we outline the most pressing directions for future research, including the steps required to use BR algorithms in wearable sensors, remote video monitoring, and clinical practice.

The acquisition and retention of ECG interpretation skills after a standardized web-based ECG tutorial-a randomised study

BACKGROUND

Electrocardiogram (ECG) interpretation is of great importance for patient management. However, medical students frequently lack proficiency in ECG interpretation and rate their ECG training as inadequate. Our aim was to examine the effect of a standalone web-based ECG tutorial and to assess the retention of skills using multiple follow-up intervals.

METHODS

203 medical students were included in the study. All participants completed a pre-test, an ECG tutorial, and a post-test. The participants were also randomised to complete a retention-test after short (2-4 weeks), medium (10-12 weeks), or long (18-20 weeks) follow-up. Intragroup comparisons of test scores were done using paired-samples t-test. Intergroup comparisons of test scores were performed using independent-samples t-test and ANOVA, whereas demographic data were compared using ANOVA and Chi-squared test.

RESULTS

The overall mean test score improved significantly from 52.7 (SD 16.8) in the pre-test to 68.4 (SD 12.3) in the post-test (p < 0.001). Junior and senior students demonstrated significantly different baseline scores (45.5 vs. 57.8 points; p < 0.001), but showed comparable score gains (16.5 and 15.1 points, respectively; p = 0.48). All three follow-up groups experienced a decrease in test score between post-test and retention-test: from 67.4 (SD 12.3) to 60.2 (SD 8.3) in the short follow-up group, from 71.4 (SD 12.0) to 60.8 (SD 8.9) in the medium follow-up group, and from 66.1 (SD 12.1) to 58.6 (SD 8.6) in the long follow-up group (p < 0.001 for all). However, there were no significant differences in mean retention-test score between the groups (p = 0.33). Both junior and senior students showed a decline in test score at follow-up (from 62.0 (SD 10.6) to 56.2 (SD 9.8) and from 72.9 (SD 11.4) to 62.5 (SD 6.6), respectively). When comparing the pre-test to retention-test delta scores, junior students had learned significantly more than senior students (junior students improved 10.7 points and senior students improved 4.7 points, p = 0.003).

CONCLUSION

A standalone web-based ECG tutorial can be an effective means of teaching ECG interpretation skills to medical students. The newly acquired skills are, however, rapidly lost when the intervention is not repeated.

Vertical P-wave axis: the electrocardiographic synonym for pulmonary emphysema and its severity

BACKGROUND

The correlation between vertical P-wave axis (P-axis > 60°) and pulmonary emphysema was investigated on a very large controlled series to see if P-axis verticalisation as lone criterion can be effectively used to screen emphysema in general population. Correlation between degrees of P-axis verticalisation and the severity of the obstructive lung disease (as per global initiative for chronic obstructive lung disease [GOLD] criteria) was also studied to see if this criterion can be used for gross quantification of the chronic obstructive pulmonary disease (COPD) in routine clinical practice.

MATERIALS AND METHODS

Around 6500 unselected, routine electrocardiograms (ECGs) were reviewed which yielded 600 ECGs with vertical P-axis in sinus rhythm. 635 ECGs from the same continuum were selected with P-axis ≤60° matched for patient's age and sex serving as controls. Charts were reviewed for the diagnosis of COPD and emphysema based on medical history, pulmonary function tests, and imaging studies.

RESULTS

Prevalence of emphysema in patients with vertical P-axis was strikingly higher than in the control group: 85% vs 4.4%. The sensitivity and specificity of vertical P-axis for diagnosing emphysema was 94.76% and 86.47%, respectively. Vertical P-axis and forced expiratory volume (FEV1) were inversely correlated (Pearson correlation coefficient=-0.683). Prevalence of severe COPD was strikingly higher in patients with P-axis > 75° as compared to the group with P-axis 60°-75°: 96.3% vs 4.6%. Close to 80% of the emphysema patients with P-axis > 85° had very severe disease (FEV1 < 30%).

CONCLUSION

P-axis verticalisation is highly effective for screening emphysema and degree of verticalisation provides a gross quantification of the disease.

Robust detection of premature ventricular contractions using a wave-based Bayesian framework

Detection and classification of ventricular complexes from the ECG is of considerable importance in Holter and critical care patient monitoring, being essential for the timely diagnosis of dangerous heart conditions. Accurate detection of premature ventricular contractions (PVCs) is particularly important in relation to life-threatening arrhythmias. In this paper, we introduce a model-based dynamic algorithm for tracking the ECG characteristic waveforms using an extended Kalman filter. The algorithm can work on single or multiple leads. A "polargram"--a polar representation of the signal--is introduced, which is constructed using the Bayesian estimations of the state variables. The polargram allows the specification of a polar envelope for normal rhythms. Moreover, we propose a novel measure of signal fidelity by monitoring the covariance matrix of the innovation signals throughout the filtering procedure. PVCs are detected by simultaneous tracking the signal fidelity and the polar envelope. Five databases, including 40 records from MIT-BIH arrhythmia database, are used for differentiating normal, PVC, and other beats. Performance evaluation results show that the proposed method has an average detection accuracy of 99.10%, aggregate sensitivity of 98.77%, and aggregate positive predictivity of 97.47%. Furthermore, the method is capable of 100% accuracy for records that contain only PVCs and normal sinus beats. The results illustrate that the method can contribute to, and enhance the performance of clinical PVC detection.

True-positive exercise electrocardiogram/false-negative thallium-201 scintigram: a proposal of a mechanism for the paradox

A 72-year-old man with exertional angina had a strongly positive exercise electrocardiogram (EECG) with a negative thallium-201 myocardial perfusion scintigram (Tl). Arteriography revealed triple-vessel coronary artery disease, for which he underwent aortocoronary bypass grafting. Repeat EECG was negative, and it was again associated with a negative Tl. The false-negative Tl on the first test was felt to be due to a rare phenomenon of homogeneously distributed reversible exercise-induced myocardial ischemia, leading to a uniform radiotracer count density. The even distribution of ischemia would also be expected to render a false-negative EECG, due to electrocardiographic cancellation, and this is frequently the case. However, in the patient presented herein, we propose that the ischemic cardiac apex rendered the EECG strongly positive because its position was not opposed by an ischemic muscular region, and thus an uncancelled ischemic ST-segment vector was generated. This hypothesis is supported by our recent work showing the unique role of the ischemic apex (among all the other myocardial territories) in rendering the EECG positive.

Antimony-induced cardiomyopathy in guinea-pig and protection by L-carnitine

Antimony (Sb) is the mainstay for the treatment of Leishmaniasis. It has serious, often lethal, cardiovascular side effects. The objective of this study was to examine the effects of Sb treatment upon the electrocardiogram (ECG), myocyte contractility (assessed by monitoring sarcomere length during field stimulation), whole-cell action potential (AP) and calcium current (I(Ca)) of the guinea-pig and to evaluate L-carnitine as a cardioprotective agent. Guinea-pigs received daily injections of either saline, Sb(V), Sb(III), L-carnitine or L-carnitine with Sb(III). Eight lead ECGs were recorded under halothane anaesthesia every 4 days. At the end of each treatment regime, animals were killed and ventricular myocytes were enzymatically isolated. Treatment with Sb(V) for 26 days prolonged the QT interval of the ECG. Treatment with Sb(III) was lethal within 2 days for approximately 50% of the animals. The survivors showed ECG alterations similar to those described in man: T wave flattening and/or inversion, depression of the ST segment, and elongation of RR and QT intervals. Their ventricular myocytes showed impaired contraction responses to changes in stimulus frequency, elongated AP and reduced I(Ca). Combined treatment with L-carnitine and Sb(III) delayed mortality. Prior treatment with L-carnitine followed by combined treatment with L-carnitine and Sb(III) reduced mortality to <10% over 12 days and these animals showed normal ECG. Their myocytes showed normal contractility and AP. It is concluded that L-carnitine has a preventive cardioprotective role against antimony-induced cardiomyopathy. The mechanism of action of L-carnitine may be to counter oxidative stress caused by Sb(III).

Do not be alarmed, the patient is monitored

Many patients are believed to be at risk of dysrhythmias and are felt to require cardiac monitoring. These patients may not be deemed ill enough to occupy a high dependency or critical care bed and are monitored on general wards. Monitoring policies vary widely not only between institutions, but also between individual medical staff. These variations occur due to differing availability of resources and due to the lack of consensus regarding the risk for an individual patient. There is no clear evidence that monitoring patients outside high dependency areas is of benefit; inappropriate use of monitoring may actually increase patient risk.