Beat-to-Beat Patterning of Sinus Rhythm Reveals Non-linear Rhythm in the Dog Compared to the Human

Abstract

The human and dog have sinus arrhythmia; however, the beat-to-beat interval changes were hypothesized to be different. Geometric analyses (R-R interval tachograms, dynamic Poincaré plots) to examine rate changes on a beat-to-beat basis were analyzed along with time and frequency domain heart rate variability from 40 human and 130 canine 24-h electrocardiographic recordings. Humans had bell-shaped beat-interval distributions, narrow interval bands across time with continuous interval change and linear changes in rate. In contrast, dogs had skewed non-singular beat distributions, wide interval bands {despite faster average heart rate of dogs [mean (range); 81 (64-119)] bpm compared to humans [74.5 (59-103) p = 0.005]} with regions displaying a paucity of intervals (zone of avoidance) and linear plus non-linear rate changes. In the dog, dynamic Poincaré plots showed linear rate changes as intervals prolonged until a point of divergence from the line of identity at a mean interval of 598.5 (95% CI: 583.5-613.5) ms (bifurcation interval). The dog had bimodal beat distribution during sleep with slower rates and greater variability than during active hours that showed singular interval distributions, higher rates and less variability. During sleep, Poincaré plots of the dog had clustered or branched patterns of intervals. A slower rate supported greater parasympathetic modulation with a branched compared to the clustered distribution. Treatment with atropine eliminated the non-linear patterns, while hydromorphone shifted the bifurcated branching and beat clustering to longer intervals. These results demonstrate the unique non-linear nature of beat-to-beat variability in the dog compared to humans with increases in interval duration (decrease heart rate). These results provoke the possibility that changes are linear with a dominant sympathetic modulation and non-linear with a dominant parasympathetic modulation. The abrupt bifurcation, zone of avoidance and beat-to-beat patterning are concordant with other studies demonstrating the development of exit block from the sinus node with parasympathetic modulation influencing not only the oscillation of the pacing cells, but conduction to the atria. Studies are required to associate the in vivo sinus node beat patterns identified in this study to the mapping of sinus impulse origin and exit from the sinus node.

Lorenz Plot Analysis in Dogs with Sinus Rhythm and Tachyarrhythmias

“…Table 1 reports the criteria of classification of LP patterns. The nomenclature already proposed in humans [2] and dogs [5][6][7] was used when the characteristics of patterns obtained from dogs included in the study were similar to those previously described; otherwise, a new nomenclature was proposed.…”

“…Table 1 reports the criteria of classification of LP patterns. The nomenclature already proposed in humans [2] and dogs [5][6][7] was used when the characteristics of patterns obtained from dogs included in the study were similar to those previously described; otherwise, a new nomenclature was proposed. Triangular with two lateral small and fusiform ECs (one left-sided and one right-sided) CC: central cluster; CSZ: central silent zone; DSL: double side lobe; EC: eccentric cluster; Lmax/Wmax: ratio of the maximal length to the maximal width; LP: Loren plot; NA: not applicable; QSL: quadruple side lobe; TSL: triple side lobe.…”

“…Therefore, LPs could represent an attractive diagnostic tool in veterinary cardiology as well. Regrettably, only a few studies have described the graphic features of LP in dogs with and without arrhythmias [3][4][5][6][7], and the only study aimed at characterizing the LP patterns in arrhythmic dogs evaluated LPs generated from 1-h Holter recordings [6].…”

Robust neuromorphic coupled oscillators for adaptive pacemakers

“…We validate our hardware model with recordings from healthy dogs at rest, including simultaneous recordings of sECG and respiratory signal traces (data provided by University Medical Center Utrecht, NL). We focus on recordings of dogs at rest because RSA is found to be more prominent under slow and deep breathing 35 , 36 , and is highly present in resting dogs 37 , 38 . We validate our model for RSA with a recording of 2.3 min showing prominent RSA modulation.…”

Autonomic modulation of ventricular electrical activity: recent developments and clinical implications

“…For example, dogs have a shorter action potential duration and a higher resting heart rate and respiratory rate [ 20 ]. Moreover, though parasympathetic tone is dominant in resting humans, the resting autonomic tone in dogs is even more heavily influenced by the parasympathetic nervous system, which is also reflected in their more pronounced respiratory sinus arrhythmia and increased heart rate variability [ 22 ]. This difference in autonomic tone must thus be carefully considered in the setting of preclinical studies in neurocardiology.…”