scholarly journals Electrocardiographic Scaling Reveals Differences in Electrocardiogram Interval Durations Between Marine and Terrestrial Mammals

2021 ◽  
Vol 12 ◽  
Author(s):  
Rhea L. Storlund ◽  
David A. S. Rosen ◽  
Andrew W. Trites
Keyword(s):  
Heart Rate ◽  
Body Mass ◽  
Marine Mammals ◽  
Physiological State ◽  
P Wave ◽  
Breath Hold ◽  
Allometric Relationships ◽  
Heart Rates ◽  
Terrestrial Mammals ◽  
Qt Intervals

Although the ability of marine mammals to lower heart rates for extended periods when diving is well documented, it is unclear whether marine mammals have electrophysiological adaptations that extend beyond overall bradycardia. We analyzed electrocardiographic data from 50 species of terrestrial mammals and 19 species of marine mammals to determine whether the electrical activity of the heart differs between these two groups of mammals. We also tested whether physiological state (i.e., anesthetized or conscious) affects electrocardiogram (ECG) parameters. Analyses of ECG waveform morphology (heart rate, P-wave duration, and PQ, PR, QRS, and QT intervals) revealed allometric relationships between body mass and all ECG intervals (as well as heart rate) for both groups of mammals and specific differences in ECG parameters between marine mammals and their terrestrial counterparts. Model outputs indicated that marine mammals had 19% longer P-waves, 24% longer QRS intervals, and 21% shorter QT intervals. In other words, marine mammals had slower atrial and ventricular depolarization, and faster ventricular repolarization than terrestrial mammals. Heart rates and PR intervals were not significantly different between marine and terrestrial mammals, and physiological state did not significantly affect any ECG parameter. On average, ECG interval durations of marine and terrestrial mammals scaled with body mass to the power of 0.21 (range: 0.19–0.23) rather than the expected 0.25—while heart rate scaled with body mass to the power of –0.22 and was greater than the widely accepted –0.25 derived from fractal geometry. Our findings show clear differences between the hearts of terrestrial and marine mammals in terms of cardiac timing that extend beyond diving bradycardia. They also highlight the importance of considering special adaptations (such as breath-hold diving) when analyzing allometric relationships.

scholarly journals High heart rates in hunting harbour porpoises

2021 ◽  
Vol 288 (1962) ◽  
Author(s):  
Birgitte I. McDonald ◽  
Siri L. Elmegaard ◽  
Mark Johnson ◽  
Danuta M. Wisniewska ◽  
Laia Rojano-Doñate ◽  
...  
Keyword(s):  
Heart Rate ◽  
Marine Mammals ◽  
Dive Duration ◽  
Breath Hold ◽  
Peripheral Tissues ◽  
Heart Rates ◽  
Record Heart Rate ◽  
Field Metabolic Rates ◽  
Dive Response

The impressive breath-hold capabilities of marine mammals are facilitated by both enhanced O 2 stores and reductions in the rate of O 2 consumption via peripheral vasoconstriction and bradycardia, called the dive response. Many studies have focused on the extreme role of the dive response in maximizing dive duration in marine mammals, but few have addressed how these adjustments may compromise the capability to hunt, digest and thermoregulate during routine dives. Here, we use DTAGs, which record heart rate together with foraging and movement behaviour, to investigate how O 2 management is balanced between the need to dive and forage in five wild harbour porpoises that hunt thousands of small prey daily during continuous shallow diving. Dive heart rates were moderate (median minimum 47–69 bpm) and relatively stable across dive types, dive duration (0.5–3.3 min) and activity. A moderate dive response, allowing for some perfusion of peripheral tissues, may be essential for fuelling the high field metabolic rates required to maintain body temperature and support digestion during diving in these small, continuously feeding cetaceans. Thus, despite having the capacity to prolong dives via a strong dive response, for these shallow-diving cetaceans, it appears to be more efficient to maintain circulation while diving: extreme heart rate gymnastics are for deep dives and emergencies, not everyday use.

scholarly journals Physiological ECG Value for Polish Half-Bred Anglo-Arab Horses

2012 ◽  
Vol 56 (4) ◽  
pp. 631-635 ◽  
Keyword(s):  
Heart Rate ◽  
P Wave ◽  
P Waves ◽  
T Wave ◽  
Duration Time ◽  
Qt Intervals ◽  
Electrocardiographic Examination ◽  
Electrocardiographic Findings ◽  
Almost All ◽  
T Waves

Abstract The electrocardiographic examination was performed in 33 training horses (2-16 years of age, 11 males and 22 females). Einthoven and precordial leads (I, II, III, aVR, aVL, aVF, CV1, CV2, CV4) were used. The ECG was performed in resting horses and immediately after exercise (10 min walk, 15 min trot, 10 min canter) using a portable Schiller AT-1 3-channel electrocardiograph, with a paper speed of 25 mm sec-1 and a sensitivity of 10 mm.mV-1. The heart rate, wave amplitudes, and duration time were estimated manually. All horses presented a significant increase in heart rate after exercise (rest 43.83 ±10.33 vs. exercise 73.2 ±14.8). QT intervals were significantly shortened in most of the leads. In resting horses, all P waves in the lead I were positive and almost all II, III and CV4 leads were positive. Simple negative P wave dominated in aVR and only simple negative T wave was found in the leads I. The biphasic shape was observed. After exercise, the amplitude of P and T waves rose, however, clear changes were not observed in wave polarisation and form. In the absence of specific racial characteristics of the electrocardiogram in the Polish Anglo- Arabians, electrocardiographic findings can be interpreted according to ECG standards adopted for horses.

scholarly journals Examining predator–prey body size, trophic level and body mass across marine and terrestrial mammals

2014 ◽  
Vol 281 (1797) ◽  
pp. 20142103 ◽  
Author(s):  
Marlee A. Tucker ◽  
Tracey L. Rogers
Keyword(s):  
Community Structure ◽  
Body Size ◽  
Body Mass ◽  
Marine Environment ◽  
Trophic Level ◽  
Marine Mammals ◽  
Trophic Position ◽  
Trophic Levels ◽  
Predator Prey ◽  
Terrestrial Mammals

Predator–prey relationships and trophic levels are indicators of community structure, and are important for monitoring ecosystem changes. Mammals colonized the marine environment on seven separate occasions, which resulted in differences in species' physiology, morphology and behaviour. It is likely that these changes have had a major effect upon predator–prey relationships and trophic position; however, the effect of environment is yet to be clarified. We compiled a dataset, based on the literature, to explore the relationship between body mass, trophic level and predator–prey ratio across terrestrial ( n = 51) and marine ( n = 56) mammals. We did not find the expected positive relationship between trophic level and body mass, but we did find that marine carnivores sit 1.3 trophic levels higher than terrestrial carnivores. Also, marine mammals are largely carnivorous and have significantly larger predator–prey ratios compared with their terrestrial counterparts. We propose that primary productivity, and its availability, is important for mammalian trophic structure and body size. Also, energy flow and community structure in the marine environment are influenced by differences in energy efficiency and increased food web stability. Enhancing our knowledge of feeding ecology in mammals has the potential to provide insights into the structure and functioning of marine and terrestrial communities.

The diving physiology of bottlenose dolphins (Tursiops truncatus). I. Balancing the demands of exercise for energy conservation at depth

1999 ◽  
Vol 202 (20) ◽  
pp. 2739-2748 ◽  
Author(s):  
T.M. Williams ◽  
J.E. Haun ◽  
W.A. Friedl
Keyword(s):  
Heart Rate ◽  
Blood Lactate ◽  
Tursiops Truncatus ◽  
Marine Mammals ◽  
Bottlenose Dolphins ◽  
Lactate Concentration ◽  
Blood Lactate Concentration ◽  
Energetic Cost ◽  
Breath Holding ◽  
Breath Hold

During diving, marine mammals must rely on the efficient utilization of a limited oxygen reserve sequestered in the lungs, blood and muscles. To determine the effects of exercise and apnea on the use of these reserves, we examined the physiological responses of adult bottlenose dolphins (Tursiops truncatus) trained to breath-hold on the water surface or to dive to submerged targets at depths between 60 and 210 m. Changes in blood lactate levels, in partial pressures of oxygen and carbon dioxide and in heart rate were assessed while the dolphins performed sedentary breath-holds. The effects of exercise on breath-hold capacity were examined by measuring heart rate and post-dive respiration rate and blood lactate concentration for dolphins diving in Kaneohe Bay, Oahu, Hawaii. Ascent and descent rates, stroke frequency and swimming patterns were monitored during the dives. The results showed that lactate concentration was 1.1+/−0.1 mmol l(−1) at rest and increased non-linearly with the duration of the sedentary breath-hold or dive. Lactate concentration was consistently higher for the diving animals at all comparable periods of apnea. Breakpoints in plots of lactate concentration and blood gas levels against breath-hold duration (P(O2), P(CO2)) for sedentary breath-holding dolphins occurred between 200 and 240 s. In comparison, the calculated aerobic dive limit for adult dolphins was 268 s. Descent and ascent rates ranged from 1.5 to 2.5 m s(−1) during 210 m dives and were often outside the predicted range for swimming at low energetic cost. Rather than constant propulsion, diving dolphins used interrupted modes of swimming, with more than 75 % of the final ascent spent gliding. Physiological and behavioral measurements from this study indicate that superimposing swimming exercise on apnea was energetically costly for the diving dolphin but was circumvented in part by modifying the mode of swimming.

scholarly journals Problems with Bazett QTc correction in paediatric screening of prolonged QTc interval

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Irena Andršová ◽  
Katerina Hnatkova ◽  
Kateřina Helánová ◽  
Martina Šišáková ◽  
Tomáš Novotný ◽  
...  
Keyword(s):  
Heart Rate ◽  
Supine Position ◽  
Qt Interval ◽  
Qtc Interval ◽  
Healthy Children ◽  
Long Qt ◽  
Normal Children ◽  
Heart Rates ◽  
Qt Intervals ◽  
Qt Syndrome

Abstract Background Bazett formula is frequently used in paediatric screening for the long QT syndrome (LQTS) and proposals exist that using standing rather than supine electrocardiograms (ECG) improves the sensitivity of LQTS diagnosis. Nevertheless, compared to adults, children have higher heart rates (especially during postural provocations) and Bazett correction is also known to lead to artificially prolonged QTc values at increased heart rates. This study assessed the incidence of erroneously increased QTc values in normal children without QT abnormalities. Methods Continuous 12-lead ECGs were recorded in 332 healthy children (166 girls) aged 10.7 ± 2.6 years while they performed postural manoeuvring consisting of episodes (in the following order) of supine, sitting, standing, supine, standing, sitting, and supine positions, each lasting 10 min. Detailed analyses of QT/RR profiles confirmed the absence of prolonged individually corrected QTc interval in each child. Heart rate and QT intervals were measured in 10-s ECG segments and in each segment, QTc intervals were obtained using Bazett, Fridericia, and Framingham formulas. In each child, the heart rates and QTc values obtained during supine, sitting and standing positions were averaged. QTc durations by the three formulas were classified to < 440 ms, 440–460 ms, 460–480 ms, and > 480 ms. Results At supine position, averaged heart rate was 77.5 ± 10.5 beat per minute (bpm) and Bazett, Fridericia and Framingham QTc intervals were 425.3 ± 15.8, 407.8 ± 13.9, and 408.2 ± 13.1 ms, respectively. At sitting and standing, averaged heart rate increased to 90.9 ± 10.1 and 100.9 ± 10.5 bpm, respectively. While Fridericia and Framingham formulas showed only minimal QTc changes, Bazett correction led to QTc increases to 435 ± 15.1 and 444.9 ± 15.9 ms at sitting and standing, respectively. At sitting, Bazett correction identified 51, 4, and 0 children as having the QTc intervals 440–460, 460–480, and > 480 ms, respectively. At sitting, these numbers increased to 118, 11, and 1, while on standing these numbers were 151, 45, and 5, respectively. Irrespective of the postural position, Fridericia and Framingham formulas identified only a small number (< 7) of children with QT interval between 440 and 460 ms and no children with longer QTc. Conclusion During screening for LQTS in children, the use of Bazett formula leads to a high number of false positive cases especially if the heart rates are increased (e.g. by postural manoeuvring). The use of Fridericia formula can be recommended to replace the Bazett correction not only for adult but also for paediatric ECGs.

The effect of age and the influence of the relative size of the heart, brain, and blood oxygen store on the responses to submersion in mallard ducklings

1981 ◽  
Vol 59 (6) ◽  
pp. 986-993 ◽  
Author(s):  
Nigel H. West
Keyword(s):  
Heart Rate ◽  
Relative Size ◽  
The Self ◽  
Blood Oxygen ◽  
Allometric Relationships ◽  
Heart Rates ◽  
Oxygen Store ◽  
Arterial Blood ◽  
The Brain ◽  
Effect Of Age

Three newly hatched mallard ducklings showed profound bradycardia on head submersion. Heart rate fell from 485 beats∙min−1 predive to 75 beats∙min−1 after 30 s. Resting heart rates in a group of eight ducklings retested at weekly intervals fell from 430 ± 13 beats∙min−1 at one week after hatching to 183 ± 27 beats∙min−1 at 12 weeks. In spite of the wide difference in resting heart rates, the proportional fall in heart rate by 30 s after head submersion was very consistent, to some 20% of the predive rate. The absolute fall in heart rate during early submergence was much greater at 1 week than at 4 weeks. Previous experience with voluntary head submersion during feeding did not affect the heart-rate response.Predive mean arterial blood pressure, which rose from 77.1 mmHg at 1 week to 180.2 mmHg at 12 weeks was maintained constant, or rose slightly, during submersion in all the animals tested. The tolerance to prolonged submersion was markedly poorer in younger ducklings; birds at 1 week only tolerated some 67 s of apnoeic asphyxia before a breakdown of the circulatory adjustments, while at 12 weeks the same birds tolerated submersion for 240 s with no ill effects. This is partially due to the changing allometric relationships during development between the mass of the brain and the heart, major components of the oxygen sink during submergence, and the blood volume, a major component of the self-contained oxygen store.

scholarly journals Total energy expenditure of bottlenose dolphins (Tursiops truncatus) of different ages

2021 ◽  
Author(s):  
Rebecca Rimbach ◽  
Ahmad Amireh ◽  
Austin Allen ◽  
Brian Hare ◽  
Emily Guarino ◽  
...  
Keyword(s):  
Energy Expenditure ◽  
Total Energy ◽  
Body Mass ◽  
Tursiops Truncatus ◽  
Marine Mammals ◽  
Bottlenose Dolphins ◽  
Large Body ◽  
Total Energy Expenditure ◽  
Natural Seawater ◽  
Terrestrial Mammals

Marine mammals are thought to have an energetically expensive lifestyle because endothermy is costly in marine environments. However, measurements of total energy expenditure (TEE; kcal/day) are available only for a limited number of marine mammals, because large body size and inaccessible habitats make TEE measurements expensive and difficult for many taxa. We measured TEE in 10 adult common bottlenose dolphins (Tursiops truncatus) living in natural seawater lagoons at two facilities (Dolphin Research Center and Dolphin Quest) using the doubly labeled water method. We assessed the relative effects of body mass, age, and physical activity on TEE. We also examined whether TEE of bottlenose dolphins, and more generally marine mammals, differs from that expected for their body mass compared to other eutherian mammals, using phylogenetic least squares (PGLS) regressions. There were no differences in body mass or TEE (unadjusted TEE and TEE adjusted for fat free mass (FFM)) between dolphins from both facilities. Our results show that Adjusted TEE decreased and fat mass (FM) increased with age. Different measures of activity were not related to age, body fat or Adjusted TEE. Both PGLS and the non-phylogenetic linear regression indicate that marine mammals have an elevated TEE compared to terrestrial mammals. However, bottlenose dolphins expended 17.1% less energy than other marine mammals of similar body mass. The two oldest dolphins (&gt;40 years) showed a lower TEE, similar to the decline in TEE seen in older humans. To our knowledge, this is the first study to show an age-related metabolic decline in a large non-human mammal.

scholarly journals The Impact of Body Mass Index on Physical Activity and Cardiac Workload

2021 ◽  
Author(s):  
Myra Jane Bloom ◽  
Lakin Mckenzie Brown ◽  
Scarlet Rae Jost ◽  
Andrew Stuart Ian Donald Lang ◽  
Nancy Viola Mankin ◽  
...  
Keyword(s):  
Physical Activity ◽  
Body Mass Index ◽  
Heart Rate ◽  
University Students ◽  
Body Mass ◽  
Healthy Lifestyle ◽  
Physically Active ◽  
Heart Rates ◽  
Healthy Lifestyle Interventions ◽  
The Impact

AbstractBackgroundHaving an abnormal body mass index (BMI) adversely affects cardiac workload and level of physical activity.ObjectiveTo examine the relationship between cardiac workload, physical activity, Sex, and BMI.MethodsThe number of steps taken per day (Steps) and minutes per week spent in targeted heart rate zones were collected from primarily first and second year university students (n = 1,801; 62% female) over a standard, 15-week long semester. Other data collected included BMI, Sex, Age, and Class Standing. Sex differences in BMI, Steps, and training heart rate zone (heart rates above 50% of max) minutes (THR) were evaluated, correlations between the study parameters were analyzed, and one-way ANOVA was used to test between competing models. The values p < .05 were considered statistically significant.ResultsStatistically significant (p < .05) differences between males and females were found for Steps, THR, and BMI. Males were more physically active but spent 18% less time with heart rates above 50% of max. Students who had abnormal BMI values, both low and high, experienced greater cardiac workload (p < .05), even though they were found to be less physically active (p < .05).ConclusionOur study revealed that university students with abnormal BMI values experienced greater cardiac workload, even though they are less physically active. Thus, physical fitness and healthy lifestyle interventions should also include underweight students in addition to students who are overweight or obese.

scholarly journals Effect of pregnancy and correlation of weight and heart rate with electrocardiographic parameters in the American Miniature Horse

2016 ◽  
Vol 68 (3) ◽  
pp. 579-586
Author(s):  
B.P. Santarosa ◽  
M.L.G. Lourenço ◽  
G.N. Dantas ◽  
C.M.V. Ulian ◽  
M.C.T. Heckler ◽  
...  
Keyword(s):  
Heart Rate ◽  
Body Weight ◽  
Frontal Plane ◽  
P Wave ◽  
Cardiac Physiology ◽  
Horse Breed ◽  
Gestational Period ◽  
Qt Intervals ◽  
Electrocardiographic Parameters ◽  
Electrocardiogram Ecg

ABSTRACT There are studies on electrocardiogram (ECG) in several breeds of horses, which highlights the growing importance of cardiology in this species. But few authors have addressed the influence of pregnancy on the cardiac physiology of the mare, and specifically, there are no studies on the Mini-horse breed, as well as no correlation of body weight (BW) and heart rate (HR) with electrocardiographic parameters in this breed. The aims of this study were to determine the effects of pregnancy on ECG parameters and to examine the relationships between these variables and body weight (BW) and heart rate (HR). A total of 203 animals were used, including 143 females (66 pregnant) and 60 males. Electrocardiographic examinations were performed by computerized electrocardiogram (TEB), and the parameters were evaluated in six leads in the frontal plane (Lead I, II, III, aVR, aVL and aVF) and base-apex (BA). BW was inversely proportional to HR, which in turn showed an inverse relationship with the duration of the P-wave and the PR and QT intervals. The P-wave amplitude (lead II) was higher in pregnant animals than in non-pregnant animals. The effect of reproductive status should be monitored by ECG throughout the entire gestational period. The 66 pregnant mares in this study were examined during the first third of their pregnancies, thus, few differences were observed between pregnant and non-pregnant animals.

scholarly journals Ventricular gradient and nondipolar repolarization components increase at higher heart rate

2004 ◽  
Vol 286 (1) ◽  
pp. H131-H136 ◽  
Author(s):  
Peter Smetana ◽  
Velislav N. Batchvarov ◽  
Katerina Hnatkova ◽  
A. John Camm ◽  
Marek Malik
Keyword(s):  
Heart Rate ◽  
Action Potential ◽  
Action Potential Duration ◽  
Rate Dependence ◽  
Rr Intervals ◽  
Heart Rates ◽  
Qt Intervals ◽  
Ion Channel Properties ◽  
Transmural Dispersion ◽  
Relationship Of

Differences in action potential duration reflect differences in ion channel properties. These properties also determine rate dependence of action potential duration, and transmural dispersion was confirmed experimentally to increase with cycle length. While several electrocardiographic indexes characterizing repolarization abnormalities have been proposed, studies of their heart rate dependence are missing. This study therefore investigated rate relationship of two repolarization descriptors, namely, the so-called total cosine of the QRS-T angle (TCRT), proposed to characterize global repolarization heterogeneity, and the so-called relative T wave residuum (TWR), linked to regional repolarization dispersion. During 24-h holter recordings in 60 healthy subjects (27 males), a 12-lead ECG was obtained every 30 s. RR intervals, QT intervals, and TCRT and TWR were calculated in each ECG and averaged over RR interval bins ranging from 550 to 1,150 ms in 10-ms steps. Women had uniformly greater TCRT and TWR values than men did over the entire range of investigated RR intervals. Whereas the TCRT in both sexes showed marked rate dependence with higher values at long RR intervals (550 vs. 1,150 ms: women, 0.46 ± 0.31 vs. 0.76 ± 0.18, P = 9 × 10–7; men, 0.08 ± 0.45 vs. 0.49 ± 0.35, P = 9 × 10–8), the rate dependence of TWR was more marked in women than in men, showing higher values at shorter RR intervals (550 ms vs. 1,150 ms: women: 0.29 ± 0.14% vs. 0.08 ± 0.06%, P = 2 × 10–8; men: 0.14 ± 0.12% vs. 0.04 ± 0.02%, P = 2 × 10–15). This suggests that both global and regional repolarization heterogeneity are increased at faster heart rates. Whereas in women at all heart rates the sequence of repolarization more closely replicates the sequence of depolarization, localized repolarization is more heterogeneous than in men especially at fast heart rates.

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