Search

The cardiac conduction system in large carnivores, such as the African lion (Panthera leo), represents a significant knowledge gap in both veterinary science and in cardiac electrophysiology. Short QT intervals have been reported from zoo‐kept, anaesthetized lions, and our goal was to record the first ECGs from wild, conscious lions roaming freely, and compare them to zoo‐kept lions under the hypothesis that short QT is unique to zoo‐kept lions. Macroscopic and histological examinations were performed on heart tissue removed from nine healthy zoo lions. ECGs were recorded from the nine anaesthetized zoo‐kept lions, and from 15 anaesthetized and conscious wild lions in Africa. Our histological and topographical description of the lion's heart matched what has previously been published. In conscious lions, the ECG recordings revealed a mean heart rate of 70 ± 4 beats/min, with faster heart rates during the night. PQ and QT intervals were heart rate dependent in the conscious lions. Interestingly, QT intervals recorded in wild lions were markedly longer than QT intervals from zoo lions (398 ± 40 vs. 297 ± 9 ms, respectively; P < 0.0001). Anaesthesia or heart rate did not account for this difference. We provide a comprehensive description of the cardiac anatomy and electrophysiology of wild and zoo‐kept lions. QT intervals were significantly shorter in zoo lions, suggesting functional disparities in cardiac electrophysiology between wild and zoo‐kept lions, potentially related to physical fitness. These findings underscore the plasticity of cardiac electrophysiology and may be of value when reintroducing endangered species into the wild and when managing lions in human care. What is the central question of this study?How do electrocardiograms from zoo lions and free‐roaming wild lions compare?What is the main finding and its importance?QT intervals in zoo lions are shorter compared to wild lions, which may be relevant for our understanding of animals in human care and may influence conservation strategies. [ABSTRACT FROM AUTHOR]

Background: The Purkinje fibers convey the electrical impulses at much higher speed than the working myocardial cells. Thus, the distribution of the Purkinje network is of paramount importance for the timing and coordination of ventricular activation. The Purkinje fibers are found in the subendocardium of all species of mammals, but some mammals also possess an intramural Purkinje fiber network that provides for relatively instantaneous, burst‐like activation of the entire ventricular wall, and gives rise to an rS configuration in lead II of the ECG. Aim: To relate the topography of the horse heart and the distribution and histology of the conduction system to the pattern of ventricular activation as a mechanism for the unique electrical axis of the equine heart. Methods: The morphology and distribution of the cardiac conduction system was determined by histochemistry. The electrical activity was measured using ECG in the Einthoven and orthogonal configuration. Results: The long axis of the equine heart is close to vertical. Outside the nodal regions the conduction system consisted of Purkinje fibers connected by connexin 43 and long, slender parallel running transitional cells. The Purkinje fiber network extended deep into the ventricular walls. ECGs recorded in an orthogonal configuration revealed a mean electrical axis pointing in a cranial‐to‐left direction indicating ventricular activation in an apex‐to‐base direction. Conclusion: The direction of the mean electrical axis in the equine heart is determined by the architecture of the intramural Purkinje network, rather than being a reflection of ventricular mass. [ABSTRACT FROM AUTHOR]

This work introduces a new formulation of the well-known data-dependent noise-predictive (DDNP) approach to whiten noise in partial response channel detection. The new approach is tailored for whitening the branches in the recently introduced symbol-based detectors that are demonstrated to have optimal performance in concatenation with non-binary error correction codes, such as non-binary low density parity check (LDPC) codes. This paper describes a new approach in the context of the perpendicular magnetic channel, where a symbol-based BCJR is concatenated with a non-binary LDPC decoder. Several approximations based on conventional DDNP implementations are suggested to quantify the performance of the new algorithm. [ABSTRACT FROM PUBLISHER]