Comparison of the spatial QRS-T angle derived from the conventional 12-lead ECG using standard electrode positions with that derived from the Holter ECG using Mason Likar electrode positions V. Salvi a , E. Clark b , D.R. Karnad a , P. Macfarlane b , G.K. Panicker a , P. Hingorani a , S. Kothari a , Y.Y. Lokhandwala a a Quintiles Cardiac Safety Services, Mumbai, India b University of Glasgow, Glasgow, UK Introduction: The spatial QRS-T angle derived from orthogonal leads is a marker for cardiac mortality. Data from 12-lead ECGs are often used to reconstruct orthogonal leads and derive the spatial QRS-T angle. The effect on the spatial QRS-T angle of using Mason Likar (M-L) electrode positions as used in Holter ECGs was studied. Methods: 12-lead ECGs were recorded simultaneously with standard limb lead positions using an ECG device and M-L lead positions using a 12-lead Holter recorder in 100 volunteers. Spatial QRS-T angles were calculated by 2 methods — a vector method within the Glasgow algorithm and a net amplitude method where net QRS [R amplitude minus Q or S amplitude (whichever is greater)] and T wave amplitudes were manually measured in derived orthogonal leads. Results: There was a small, statistically significant difference in spatial QRS-T angles from standard and M-L ECGs (57º ± 18º vs. 48º ± 20º respectively using the net amplitude method and 53º ± 28º vs. 48º ± 23º respectively by the vector method). This was due to differences in QRS and T amplitudes in derived leads Y and Z probably resulting from differences in leads I and II (Table 1). Although dual snap electrodes were used, QRS and T amplitudes in leads V4–V6 also differed between the two lead systems probably due to a difference in potential at the central terminal. Conclusion: There is a small, statistically significant difference in spatial QRS-T angles derived from 12-lead ECGs using standard and M-L lead systems. However, this difference may not be clinically significant. http://dx.doi.org/10.1016/j.jelectrocard.2013.05.044 Cardiac arrhythmia induced by hypothermia in a cardiac model in vitro B. Xu a , S. Jacquir b , O. Pont a , H. Yahia a a Team GeoStat - INRIA Bordeaux Sud-Ouest b CNRS UMR 5158 Dijon France, LE2I Université de Bourgogne Introduction: The neurological damage after cardiac arrest (CA) has presented a big challenge to hospital discharge for many years. The thera- peutic hypothermia therapy (34 °C–32 °C) has shown its benefit to reduce cerebral oxygen demand and improve neurological outcomes after cardiac arrest. Despite the fact that induced hypothermia after CA has been shown to increase the hospital survival rate, it can have many adverse effects, among which the generation of cardiac arrhythmias represents an important part (up to 34%, according to different clinical studies). Compared to studies in vivo, cardiac culture in vitro provides a better spatial resolution at cellular level, which could bring some insights into the mechanism of post– hypothermia arrhythmia (PHA) generation. Method: Monolayer cardiac culture is prepared with cardiomyocytes from the new-born rat (1–4 days) directly on the MEA at 37 °C. The experiments consist of culture cooling (37 °C–30 °C) and re-warming (30 °C–37 °C). The acquired signals are then analyzed with detrended fluctuation analysis (DFA) and phase space reconstruction (PSR). Results: Both experiments showed that period-doubling phenomena are present at 35 °C, which can be translated as a transit point from the normal state to the chaos state, from the point view of nonlinear dynamics. Spiral waves are observed in the reconstructed activation map which is commonly considered as a sign of cardiac arrhythmia. Below 35 °C, the signals became regular. However, another transit point is found between 30 °C–33 °C, which agreed with other studies that hypothermia below 32 °C could induce arrhythmia. These results are confirmed by DFA and PSR methods. Conclusion: The general hypothermia therapy uses constant cooling or re-warming. Results in this study showed that a variable speed, especially fast passing 35 °C, would help to reduce the rate of post-hypothermia arrhythmia. http://dx.doi.org/10.1016/j.jelectrocard.2013.05.045 Electrocardiography of Takotsubo syndrome J.E.M. Madias Mount Sinai School of Medicine of the New York University/Cardiology Division, Elmhurst Hospital Center Introduction: The electrocardiogram (ECG) in patients presenting with the Takotsubo syndrome (TTS) does not show specific features for this disorder which are adequate to differentiate it from those encountered in acute coronary syndromes (ACS) or acute pericarditis (AP). The literature emphasizes the transient ST-segment elevation, followed by T-wave inversion and QTc interval prolongation, all of which may even be absent early in the clinical course of patients with TTS. Some recent insight associates myocardial edema, as detected by cardiac magnetic resonance imaging in patients with TTS, with attenuation (ATT) in the ECG voltage (J Electrocariol. 2012;45:795–6). Methods: The entire literature of 614 published papers, searched for in PubMed, via the MeSH term “electrocardiogram in takotsubo syndrome”, was reviewed and analyzed for the presence of low voltage ECG (LVECG) based on 1 ECG, or ATT based on ≥ 2 ECGs, in 368 patients who presented to the hospital with documented TTS. Results: LVECG was seen in 91.5% of 200 patients with TTS and 1 ECG, and ATT was seen in 93.5% of 168 patients with TTS and ≥ 2 ECGs. Conclusion: LVECG and ATT are very sensitive and specific ECG signs for TTS, and may be employed to differentiate TTS from ACS and AP. http://dx.doi.org/10.1016/j.jelectrocard.2013.05.046 Signal averaged electrocardiography in elderly hypertensive patients I. Mozos, M. Hancu, L. Susan “Victor Babes” University of Medicine and Pharmacy, Timisoara, Romania Introduction: Signal averaged electrocardiography detects late ventric- ular potentials, as markers of sudden cardiac death risk. The present study hypothesized that aging increases the prevalence of late ventric-ular potentials. Methods: A total of 40 hypertensive patients, 73% males, underwent signal averaged electrocardiography. The ages of the participants were 61 ± 12 years, 43% of them being elderly (≥ 65 years). The positive criteria for late ventricular potentials were: QRS duration (SA-QRS) N 120 ms, LAS40 (the duration of the signal at the end of the QRS complex with an amplitude below 40 μV –”Low Amplitude Signal”) N 38 ms and RMS40 (”Root Mean Square”– the square root of the last 40 ms of the signal) b 20 μV. Results: SA-QRS was longer than 120 ms, LAS40 longer than 38 ms, and RMS40 up to 20 μV, in 25%, 38% and 60% of the patients, respectively. One and two positive criteria were detected in 60% and 40% of the patients, respectively (LVP1 and LVP2). Elderly patients were more likely to have longer SA-QRS (OR = 2.591, 95% CI: 0.598–11.234) and LAS40 (OR = Table 1 QRS and T wave amplitudes in standard and M-L ECGs by net amplitude method. Parameter QRS amplitude (μV) T amplitude (μV) Standard leads M-L Leads Standard leads M-L leads Lead X 1209 ± 362 1218 ± 376 388 ± 122⁎ 413 ± 134 Lead Y 672 ± 266⁎ 1059 ± 365 200 ± 86⁎ 318 ± 118 Lead Z 400 ± 380⁎ 451 ± 395 330 ± 184⁎ 344 ± 179 Lead I 567 ± 324⁎ 253 ± 237 287 ± 95⁎ 208 ± 82 Lead II 915 ± 297⁎ 1248 ± 414 357 ± 109⁎ 471 ± 148 ⁎ p b 0.001 vs. M-L leads by paired t-test. e12 Abstract / Journal of Electrocardiology 46 (2012) e1–e37