scholarly journals The dive response redefined: underwater behavior influences cardiac variability in freely diving dolphins

2012 ◽  
Vol 215 (16) ◽  
pp. 2735-2741 ◽  
Author(s):  
S. R. Noren ◽  
T. Kendall ◽  
V. Cuccurullo ◽  
T. M. Williams
Keyword(s):  
Cardiac Variability ◽  
Dive Response

Linear and Fractal Heart Rate Dynamics during Sleep at High Altitude

2010 ◽  
Vol 49 (05) ◽  
pp. 521-525 ◽  
Author(s):  
P. Castiglioni ◽  
F. Rizzo ◽  
A. Faini ◽  
P. Mazzoleni ◽  
C. Lombardi ◽  
...  
Keyword(s):  
Heart Rate ◽  
High Altitude ◽  
Cardiac Response ◽  
Fluctuation Analysis ◽  
Similarity Coefficients ◽  
Mount Everest ◽  
Heart Rate Dynamics ◽  
Biological Interpretation ◽  
Additional Support ◽  
Cardiac Variability

Summary Objectives: To investigate the effects of hypoxia during sleep on linear and self-similar components of heart rate variability (HRV) in eight healthy subjects at high altitude on Mount Everest. Methods: ECG was monitored by using an innovative textile-based device, the MagIC system. For each subject three night recordings were performed at sea level (SL), at 3500 m and 5400 m above SL. RR Interval (RRI) was derived on a beat-by-beat basis from the ECG and the VLF, LF and HF spectral components and the LF/HF ratio were estimated. Short-(α1) and long-term (α2) scale exponents as well as the recently proposed spectrum of self-similarity coefficients, α(n) were estimated by detrended fluctuation analysis (DFA). Results: With respect to SL, all HRV parameters but one (α2) were significantly modified at 3500 m. However, at 5400 m they tended to return to the SL values and this was in contrast with the increase in the hypobaric hypoxia and in the number of central sleep apneas occurring at higher altitude. The only HRV index that displayed changes at 5400 m was the DFA α(n) spectrum, with α(n) values significantly lower than at SL for 20 < n < 50 and higher for 200 < n < 400, being n the box size.. Conclusions: While the biological interpretation of these results is still in progress, our data indicates that the cardiac response to high altitude hypoxia during sleep can hardly be fully explored by traditional HRV estimators only, and requires the additional support of more sophisticated indexes exploring also nonlinear and fractal features of cardiac variability.

scholarly journals Cardiac Variability and Heart-Rate Increment as a Marker of Sleep Fragmentation in Patients With a Sleep Disorder: a Preliminary Study

SLEEP ◽  
2007 ◽  
Vol 30 (1) ◽  
pp. 43-51 ◽  
Author(s):  
Emilia Sforza ◽  
Vincent Pichot ◽  
Katerina Cervena ◽  
Jean Claude Barthélémy ◽  
Frederic Roche
Keyword(s):  
Heart Rate ◽  
Sleep Disorder ◽  
Sleep Fragmentation ◽  
Preliminary Study ◽  
Cardiac Variability

Detection of Cardiac Variability in the Isolated Rat Heart

2006 ◽  
Vol 8 (1) ◽  
pp. 55-66 ◽  
Author(s):  
Autumn M. Schumacher ◽  
Joseph P. Zbilut ◽  
Charles L. Webber ◽  
Dorie W. Schwertz ◽  
Mariann R. Piano
Keyword(s):  
Rat Heart ◽  
Left Ventricular Pressure ◽  
Left Ventricular ◽  
Isolated Rat Heart ◽  
Rat Hearts ◽  
Before And After ◽  
Quantification Analysis ◽  
Physical Attributes ◽  
Cardiac Variability ◽  
Isolated Rat

Cardiac variability can be assessed from two perspectives: beat-to-beat performance and continuous performance during the cardiac cycle. Linear analysis techniques assess cardiac variability by measuring the physical attributes of a signal, whereas nonlinear techniques evaluate signal dynamics. This study sought to determine if recurrence quantification analysis (RQA), a nonlinear technique, could detect pharmacologically induced autonomic changes in the continuous left ventricular pressure (LVP) and electrographic (EC) signals from an isolated rat heart—a model that theoretically contains no inherent variability. LVP and EC signal data were acquired simultaneously during Langendorff perfusion of isolated rat hearts before and after the addition of acetylcholine (n = 11), norepinephrine (n = 12), or no drug (n = 12). Two-minute segments of the continuous LVP and EC signal data were analyzed by RQA. Findings showed that%recurrence,%determinism, entropy, maxline, and trend from the continuous LVP signal significantly increased in the presence of both acetylcholine and norepinephrine, although systolic LVP significantly increased only with norepinephrine. In the continuous EC signal, the RQA trend variable significantly increased in the presence of norepinephrine. These results suggest that when either the sympathetic or parasympathetic division of the autonomic nervous system overwhelms the other, the dynamics underlying cardiac variability become stationary. This study also shows that information concerning inherent variability in the isolated rat heart can be gained via RQA of the continuous cardiac signal. Although speculative, RQA may be a tool for detecting alterations in cardiac variability and evaluating signal dynamics as a nonlinear indicator of cardiac pathology.

scholarly journals Is V̇O2 supressed during nonapnoeic facial submersion?

2016 ◽  
Vol 41 (11) ◽  
pp. 1171-1176 ◽  
Author(s):  
Sarah Anderson ◽  
Maggie R. Chamberlain ◽  
Samantha Musgrove ◽  
Antonia Partusch ◽  
Keagan R.J. Tice ◽  
...  
Keyword(s):  
Heart Rate ◽  
Oxygen Consumption ◽  
Repeated Measures ◽  
Cold Shock ◽  
Repeated Measures Anova ◽  
Peripheral Vasoconstriction ◽  
Cold Shock Response ◽  
Metabolic Cart ◽  
Shock Response ◽  
Dive Response

The mammalian dive response (DR) is described as oxygen-conserving based on measures of bradycardia, peripheral vasoconstriction, and decreased ventilation (V̇E). Using a model of simulated diving, this study examined the effect of nonapnoeic facial submersions (NAFS) on oxygen consumption (V̇O2). 19 participants performed four 2-min NAFS with 8 min of rest between each. Two submersions were performed in 5 °C water, 2 in 25 °C water. Heart rate (HR) was collected using chest strap monitors. A tube connected to the inspired port of a non-rebreathing valve allowed participants to breathe during facial submersion. Expired air was directed to a metabolic cart to determine V̇O2 and V̇E. Baseline (BL) HR, V̇O2, and V̇E values were determined by the average during the 2 min prior to facial submersion; cold shock response (CSR) values were the maximum during the first 30 s of facial submersion; and NAFS values were the minimum during the last 90 s of facial submersion. A 2-way repeated-measures ANOVA indicated that both HR and V̇E were greater during the CSR (92.5 ± 3.6 beats/min, 16.3 ± 0.8 L/min) compared with BL (78.9 ± 3.2 beats/min, 8.7 ± 0.4 L/min), while both were decreased from BL during the NAFS (60.0 ± 4.0 beats/min, 6.0 ± 0.4 L/min) (all, p < 0.05). HRCSR was higher and HRNAFS lower in 5 °C versus 25 °C water (p < 0.05), while V̇E was greater in 5 °C conditions (p < 0.05). V̇O2 exceeded BL during the CSR and decreased below BL during the NAFS (BL: 5.3 ± 0.1, CSR: 9.8 ± 0.4, NAFS: 3.1 ± 0.2 mL·kg−1·min−1, p < 0.05). The data illustrate that NAFS alone contributes to the oxygen conservation associated with the human DR.

Sign in / Sign up

Export Citation Format

Share Document