Search

Electrocardiography represents a relevant diagnostic tool for detecting cardiac disease in animals. Elephants can present various congenital and acquired cardiovascular diseases. However, few electrophysiologic studies have been reported in captive elephants, mainly due to challenging technical difficulties in obtaining good-quality electrocardiogram (ECG) tracings, and no data are currently available for free-ranging Asian elephants ( Elephas maximus). The purpose of this pilot prospective study was to evaluate the feasibility of using a simple method for recording ECG tracings in wild, apparently healthy, unsedated Asian elephants ( n = 7) in the standing position. Successful six-lead recordings (I, II, III, aVR, aVL, and aVF) were obtained, with the aVL lead providing the best-quality tracings in most animals. Variables measured in the aVL lead included heart rate, amplitudes and duration of the P waves, QRS complexes, T and U waves, and duration of the PR, QT, and QU intervals. A negative deflection following positive P waves, representative of an atrial repolarization wave (Ta wave), was observed for five out of the seven elephants. [ABSTRACT FROM AUTHOR]

Objective The aim of this study is to characterize the observable segment of the atrial repolarization (Ta wave) of the standard ECG during sinus rhythm in paroxysmal atrial fibrillation (PAF) patients and controls. Methods Ta and P waves were measured from signal-averaged recordings of a standard 12-lead ECG in 40 patients, 20 with PAF, but in SR at the time of recording, and 20 healthy controls. Wave amplitudes and morphologies were measured. Results There were no significant differences in Ta amplitude between the PAF patients and controls. A subgroup analysis of patients on and off anti-arrhythmic drugs also showed no significant differences in Ta amplitudes. For both groups Ta wave had opposite polarity to the monophasic P wave. Biphasic P waves had Ta polarity opposite to the initial phase of the P wave. Ta wave amplitudes were largest in leads II (mean ± SD, -25 ± 16 μV), V2 (-22 ± 10 μV), V3 (-21 ± 10 μV) and V4 (-20 ± 8 μV). A significant correlation was found between Ta and P wave amplitudes, leads recording larger P waves also had larger Ta waves (PAF group: r = 0.15 (P = 0.02) PAF vs r = 0.33 (P = 0.002) HC). Conclusion No differences in the amplitude of the observable section of the atrial repolarization phase of the ECG could be observed between patients with PAF and controls. Ta wave correlates with the corresponding P wave in both amplitude and polarity. [ABSTRACT FROM AUTHOR]

Abstract: The repolarizing Ta wave of normal sinus rhythm is not fully visible unless there is a long P-R interval or complete atrioventicular block. Even with the latter, it is often of unseeably low voltage. It can powerfully influence inferior lead ST deviation in the stress test. The Ta of inverted or retrograde P waves is of higher voltage than that of sinus rhythm and can simulate inferior injury. Evidence of specialized internodal tracts resides in 2 specific atrial action potential properties: resistance to gross hyperkalemia and supernormality. The Ta wave figures essentially in the diagnosis of acute atrial infarction. [Copyright &y& Elsevier]