Skip to main page content
Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2016 Nov 15;5(11):1752-1757.
doi: 10.1242/bio.020909.

A Portable Infrared Photoplethysmograph: Heartbeat of Mytilus Galloprovincialis Analyzed by MRI and Application to Bathymodiolus Septemdierum

Affiliations
Free PMC article

A Portable Infrared Photoplethysmograph: Heartbeat of Mytilus Galloprovincialis Analyzed by MRI and Application to Bathymodiolus Septemdierum

Eriko Seo et al. Biol Open. .
Free PMC article

Abstract

Infrared photoplethysmogram (IR-PPG) and magnetic resonance image (MRI) of the Mytilus galloprovincialis heart were obtained simultaneously. Heart rate was varied by changing temperature, aerial exposure and hypoxia. Higher heart rates (35-20 beat min-1) were usually observed at 20°C under the aerobic condition, and typical IR-PPG represented a single peak (peak v). The upward and downward slopes of the peak v corresponded to the filling and contracting of the ventricle, respectively. A double-peak IR-PPG was observed in a wide range of heart rates (5 to 35 beats min-1) under various conditions. The initial peak v corresponded to the filling of the ventricle, and the origin of the second peak (v') varied with the heart rate. A flat IR-PPG with a noise-level represented cardiac arrest. Although large movement of the shells and the foot caused slow waves or a baseline drift of the IR-PPG, the heart rate can be calculated from the v-v interval. Based on these results, we assembled a portable IR-PPG recording system, and measured the heartbeats of Bathymodiolus septemdierum (Mytilidae) for 24 h on a research vessel just after sampling from the deep sea, showing that IR-PPG is a noninvasive, economical, robust method that can be used in field experiments.

Keywords: Arrhythmia; Bivalve; Cardiac arrest; Cardiac cycle; MRI; Plethysmography.

Conflict of interest statement

The authors declare no competing or financial interests.

Figures

Fig. 1.
Fig. 1.
IR-PPG and T1w-MRI of regular heartbeat of Mytilus galloprovincialis. The IR-PPG is shown as a solid line. The T1w-MR image intensities of the ventricle, auricle and anterior oblique vein are shown as open circle, closed circles and triangles, respectively. (I) Single-peak IR-PPG observed at 21°C in the immersed condition. The labels v and a indicate a sharp peak and a slow increase, respectively. The timing of the sagittal T1w-MRI is shown by the arrowheads labeled A to B. A, ventricular filling and contraction of the hemolymph into the ventricle. B, filling of the hemolymph into the auricles. The heart rate calculated from the v-v interval and that from the peak-peak interval of the ventricle were 32.4±1.5 bpm (n=43) and 32.5±3.2 bpm (n=43), respectively. The number (n) represents the number of heartbeats used for the calculations. (II) IR-PPG of a single peak with a small splitting observed at 21°C in the immersed condition. The labels v and v’ indicate a main peak and a small second-peak, respectively. The timing of the sagittal T1w-MRI is shown by the arrowheads labeled A to D, and detailed in the corresponding panels A-D underneath. A, end of the filling of hemolymph into the ventricle. B, ventricular contraction. C, filling of the hemolymph into the auricles. D, opening of the AV valve. The heart rates calculated from IR-PPG and MRI were 34.4±0.81 bpm (n=22) and 34.9±3.1 bpm (n=22), respectively. (III) Double-peak IR-PPG observed at 10°C in the emersed hypoxic condition. The labels v, v’ and a indicate two peaks and a slow increase, respectively. The timing of the transverse T1w-MRI is shown by the arrowheads labeled A to E, and detailed in the corresponding panels A-E underneath. A, end of the filling of hemolymph into the ventricle. B, start of the ventricular contraction. C, filling of the hemolymph into the anterior oblique vein. D, end of ventricular contraction. Flows in the ventricle and posterior aorta still continued. E, opening of the AV valve. The heart rates calculated from IR-PPG and MRI were 9.37±0.67 bpm (n=11) and 9.35±0.78 bpm (n=11), respectively. In panels IIA and IIIA, A, anterior; P, posterior; D, dorsal; V, ventral; R, right; L, left.
Fig. 2.
Fig. 2.
Heart rate observed by MRI and IR-PPG. Correlation of the heart rate calculated from the v-v interval of the IR-PPG (HRppg) and that from the interval of ventricular contraction detected by MRI (HRmri). Means and s.d. of seven sessions from four mussels are shown. Data labeled #1 and #3 were obtained in the sessions shown in Fig. 1 and Fig. 3, respectively. The number (n) represents the number of heartbeats used for the calculations. R2 is a coefficient of determination of the regression line estimated from the seven sessions.
Fig. 3.
Fig. 3.
Artifacts in IR-PPG of Mytilus galloprovincialis. The IR-PPG is shown as a solid line. The area of the water flow in the mantle cavity is shown as a dotted line. The T1w-MR image intensities of the ventricle, anterior oblique vein and gill vessel are shown as open circle, triangles, and crosses, respectively. (I) Restart of the heartbeat after cardiac arrest observed at 20°C in the emersed condition. The timing of the transverse T1w-MRI is shown by the arrowheads labeled A to E, and detailed in the corresponding panels A-E underneath. A, cardiac arrest. B, slow increase of flow in the gill vessels. C, slow increase of flows in the anterior oblique veins and the lower mantle cavity. D, ventricular contraction restarted. E, ventricular contraction three beats after the start of the heartbeat. Asterisk indicates peak of an unknown origin. (II) Slow wave in IR-PPG and close/open process of the shells observed at 20°C in the immersed condition. The timing of the transverse T1w-MRI at the end of the filling of the ventricle is shown by the arrowheads labeled A to D, and detailed in the corresponding panels A-D underneath. A, the mussels kept their shells open. B, the mussels started to closure their shells. C, the mussels closed their shells. D, the mussels reopened their shells. The upper and lower mantle cavities are divided by the W-shaped gill depicted black in T1w-MRI. In panels IA and IIA, D, dorsal; V, ventral; R, right; L, left.
Fig. 4.
Fig. 4.
Portable IR-PPG recording system and IR-PPG of Bathymodiolus septemdierum at 5°C. (A) The IR-PPG recording system for the cold room in the research vessel, Kaiyo. It consists of two boxes of IR-PP, an MR8870 digital data recorder, and two IR sensors in sample containers. Total weight of the system is around 1.5 kg, and it can set in a space of 40 cm square. (B) Bathymodiolus septemdierum and an IR sensor fixed with adhesive rubber. (C-E) IR-PPG of Bathymodiolus septemdierum at 5°C recorded in the research vessel, Kaiyo, within 24 h after sampling. (C) Regular heartbeat observed at 23 h 40 min after sampling. The heart rates calculated from IR-PPG were 6.53±0.25 bpm (n=54). (D) Bradycardia observed at 21 h 20 min after sampling. The heart rates calculated from IR-PPG were 0.97±0.07 bpm (n=7). (E) Arrhythmia including cardiac arrest observed at 20 h 00 min after sampling. The number (n) represents the number of heartbeats used for the calculations.

Similar articles

See all similar articles

Cited by 3 articles

References

    1. Bakhmet I. N., Fokina N. N., Nefedova Z. A. and Nemova N. N. (2009). Physiological-biochemical properties of blue mussel Mytilus edulis adaptation to oil contamination. Environ. Monit. Assess. 155, 581-591. 10.1007/s10661-008-0457-5 - DOI - PubMed
    1. Bakhmet I. N., Kantserova N. P., Lysenko L. A. and Nemova N. N. (2012). Effect of copper and cadmium ions on heart function and calpain activity in blue mussel Mytilus edulis . J. Environ. Sci. Health A 47, 1528-1535. 10.1080/10934529.2012.680393 - DOI - PubMed
    1. Bakhmet I., Abessa D. M. S., Buruaem L. M. and Bonnail E. (2015). A non-invasive technique for recording the cardiac activity of the tropical-subtropical mangrove oyster Crassostrea brasiliana. Pan-Am. J. Aquat. Sci. 10, 249-253.
    1. Bayne B. L. (1976). Marine Mussels: their ecology and physiology, pp. 506 Cambridge: Cambridge University Press.
    1. Bayne B. L., Bayne C. J., Carefoot T. C. and Thompson R. J. (1976). Physiological ecology of Mytilus californianus Conrad. 1. Metabolism and energy-balance. Oecologia 22, 211-228. 10.1007/BF00344793 - DOI - PubMed

LinkOut - more resources

Feedback