A new method for ECG recording in the prone position

Introduction Prone ventilation is frequently used in critical patients. ECG is usually recorded transposing the precordial positions to the back (Fig. 1A). The resultant precordial leads are unpredictably different from the supine ECG and difficult to interpret. According to the dipole theory and the concept of mirror image electrocardiogram, each precordial point has an antipodal area where a mirror precordial lead can be recorded. Fig. 1B shows the location of the antipodal areas for the precordial points Purpose Based on this theoretical background we propose to use these antipodal areas to record inverted precordial leads (mirror leads M1 – M6) with diagnostic and monitoring potential. Patients and methods We have placed the precordial electrodes in the corresponding antipodal area for each precordial point (Fig. 1B) and we have recorded prone ECG in 20 subjects (10 healthy volunteers, 10 cardiac patients) The resultant ECGs (leads M1-M6) were compared with the standard supine ECGs (v1-V6). Results Mirror leads show low amplitude (especially V2-V4) compared to standard precordials, but are qualitatively quite similar (but inverted) to the supine precordial leads (Fig. 2). Conclusion We proposed a new method to obtain ECGs in prone patients. The resultant precordial leads are comparable to the standard precordial leads. FUNDunding Acknowledgement Type of funding sources: None. Figure 1 Figure 2

Einthoven and precordial lead accuracy of smartwatch-acquired electrocardiographs: a review of the literature

IntroductionThis review aims to summarise the literature regarding the ability of commercial smartwatch products to produce an electrocardiograph of diagnostic quality for interpreting Einthoven and precordial leads. Methods PubMed, Embase, MEDLINE Complete, Web of Science, and Scopus were systematically searched. Articles were screened by a sole investigator against the inclusion criteria – first by title, then abstract, then full text. The reference lists of included articles were also screened. The inclusion criteria were: discussion of smartwatch-acquired tracing of Einthoven or precordial lead accuracy, and demonstrating sufficient rigor when undergoing critical appraisal using the Joanna Briggs Institute evaluation tools. A synopsis of results was provided in a summary of information table. ResultsTwelve articles were identified for inclusion, nine of which had physician (cardiology or emergency specialty) evaluation of tracings, one of which had statistical comparison of wave duration and amplitude, and two of which were expert commentary. Only evaluations of Apple Watch products were discovered during the literature search. All leads in all studies were considered suitable for interpretation, with no clinically significant differences. Four studies found that 100% of patients were able to accurately use a smartwatch as an electrocardiogram after a brief tutorial. ConclusionThe current early evidence, based largely on visual evaluations by cardiologists during the previous year, suggests that electrocardiograph abnormality recorded by this technology is sufficiently precise to be presumed accurate until proven otherwise.

The ‘double transition’: a novel electrocardiogram sign to discriminate posteroseptal accessory pathways ablated from the right endocardium from those requiring a left-sided or epicardial coronary venous approach

Aims The precise localization of manifest posteroseptal accessory pathways (APs) often poses diagnostic challenges considering that a small area may encompass AP that may be ablated from the right or left endocardium, or epicardially within the coronary sinus (CS). We sought to explore whether the QRS transition pattern in the precordial lead may help to discriminate the necessary ablation approach. Methods and results Consecutive patients who underwent a successful ablation of a single manifest AP over a 5-year period were included. Standard 12-lead electrocardiograms were reviewed. A total of 273 patients were identified. Mean age was 31 ± 15 years and 62% were male. Of the 110 identified posteroseptal AP, 64 were ablated from the right endocardium, 33 from the left endocardium, and 13 inside the CS. While a normal precordial QRS transition was most often observed, a subset of 33 patients presented an atypical ‘double transition’ pattern which specifically identified right endocardial AP. The combination of a q wave in V1 with a proportion of the positive QRS component in V1 < V2 > V3, predicted a right endocardial AP with a 100% specificity. In case of a positive QRS sum in V2, this ‘double transition’ pattern predicted a posteroseptal right endocardial AP with 99.5% specificity and 44% sensitivity. The positive predictive value was 97%. The only false positive was a midseptal AP. In the case of a negative or isoelectric QRS sum in V2, APs were located more laterally on the tricuspid annulus. Conclusion The combination of a q wave in V1 with a double QRS transition pattern in the precordial leads is highly specific of a right endocardial AP and rules out the need for CS or left-sided mapping.

Electrocardiographic markers of myocardial conduction and repolarization in Boxer dogs

ABSTRACT: Electrocardiographic markers have been used in people to classify arrhythmogenic risk. The aims of this study were to investigate electrocardiographic markers of conduction and repolarization in Boxers and non-Boxer dogs, and compare such findings between groups. Ten-lead standard electrocardiograms of Boxer dogs and non-Boxers recorded from 2015 to 2018 were retrospectively reviewed. Dogs ≥4 years of age and weighing >20kg were included. Animals with valvular insufficiencies, congenital cardiopathies, cardiac dilation, suspected systolic dysfunction, biphasic T-wave, bundle branch blocks, and those receiving antiarrhythmics were excluded. Electrocardiographic markers of conduction, QRS duration (QRSd) and dispersion (QRSD), and repolarization (corrected QT interval, Tpeak-Tend, JT and JTpeak), as well as derived indices, were measured. Two hundred dogs met the inclusion/exclusion requirements, including 97 Boxers (8.1±2.5 years old; 30±7kg) and 103 non-Boxer (8.8±2.5 years old, 30±8kg). QRSd and QRSD, and repolarization markers in lead II and left precordial lead V4 were considered similar between groups. Dispersion of late repolarization on lead rV2, Tpeak-Tend interval, was considered longer in Boxers (45±8ms vs 38±10ms, P=0.01). The Tpeak-Tend/JTpeak and the JTpeak/JT also differed between groups. Our results indicate that the dispersion of myocardial late repolarization in lead rV2 is slower in Boxers than other dog breeds.

Assessment of cardiac variables using a new electrocardiography lead system in horses

Aim: The objective of this study was to assess a new lead system method to improve electrocardiographic measurement in horses. Materials and Methods: Twenty-two horses with an average age of 8.8±0.8 years were enrolled in this study. Horses were divided into two groups, consisting of a control group (n=11) and athlete group (n=11). Electrocardiography (ECG) and echocardiography were performed to provide information on the structure and function of the heart. Two lead systems, base apex and modified precordial leads, were used for the electrocardiogram to assess the cardiac electrophysiological functions. Results: PR interval, QT interval, and QRS-T angle presented significant differences between the control and athlete groups when the modified precordial lead system was used. However, significant variations in the mean electrical axis were found when the base apex lead system was used. The modified precordial lead system resulted in more significant differences in cardiac electrophysiological parameters than the base apex lead system. In the athlete group, echocardiography showed cardiac adaptations such as increases in the left atrial and left ventricular dimensions and stroke volume and a decrease in heart rate in response to exercise and training. The observed differences in cardiac morphology and function between groups suggested differences in health performance in the athlete group. Conclusion: These data provided the first evidence that the modified precordial lead system improved statistical variation in ECG recording and provided the most reliable method for health screening in horses.