Development of bioimpedance sensing device for wearable monitoring of the aortic blood pressure curve

2018 ◽  
Vol 85 (5) ◽  
pp. 366-377 ◽  
Author(s):  
H. Kõiv ◽  
M. Rist ◽  
M. Min
Keyword(s):  
Blood Pressure ◽  
Blood Vessel ◽  
Axillary Artery ◽  
Vital Signs ◽  
Assessment Method ◽  
Pressure Curve ◽  
Aortic Blood ◽  
Vessel Volume ◽  
Aortic Blood Pressure

Abstract Wearable devices that monitor our vital signs have been gaining more importance with each year. Non-invasive, continuous, accurate and precise blood pressure assessment method integrated in a wearable is a multidisciplinary challenge. This work presents an electrical bioimpedance (EBI) unit for multi-frequency measurements on pulsating artery for central aortic pressure (CAP) estimation. The developed device provides low complexity in the electronics design with a frequency range between 1 kHz and 200 kHz. It is able to register the impedance of blood vessel volume change simultaneously at different locations. Experiments were carried out in vivo by using the four-electrode configuration on human thorax, axillary artery and radial artery. Preliminary results show the applicability of the proposed impedance spectroscopy system to measure blood vessel volume changes. The impedance data can be later interpreted into the aortic blood pressure wave by using a generalized transfer function. In addition, experimental test-phantom and electrode design are introduced for testing purposes of the impedance system.

scholarly journals Nervous control of the blood pressure in the Atlantic cod, Gadus morhua

1985 ◽  
Vol 117 (1) ◽  
pp. 335-347 ◽  
Author(s):  
D. G. Smith ◽  
S. Nilsson ◽  
I. Wahlqvist ◽  
B. M. Eriksson
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Blocking Agent ◽  
Adrenergic Innervation ◽  
Nervous Control ◽  
Aortic Blood ◽  
Aortic Blood Pressure

Dorsal (PDA) and ventral aortic blood pressure (PVA) and heart rate (HR) were measured in conscious resting cod, Gadus morhua L., which has been allowed 24 h recovery from surgery. Plasma adrenalin and nonadrenalin concentrations in these fish were 3.4 and 2.2 nmoll-1 respectively, and thus lower than previously reported values from partially recovered cod. Twenty-four hours after treatment with the adrenergic neurone blocking agent bretylium, PDA was significantly reduced by 17% compared to sham-injected controls, although PVA and heart rate were unaltered. Subsequent alpha-adrenoceptor blockade by phentolamine produced no further fall in PDA and no changes in PVA or HR, provided a 5-h period was allowed to overcome the acute toxic side effects of phentolamine. The effectiveness of the bretylium or phentolamine blockade was confirmed by noting the absence of any vasoconstrictor response during sympathetic nerve stimulation in perfused tails from fish used in the in vivo experiments. Bretylium had no significant effect on the sensitivity of the isolated coeliac artery to adrenalin, but effectively blocked the adrenergic innervation of this artery or the vasculature of the tail. Evidence for a non-selective blockade of non-adrenergic nerves to the heart was also obtained. It is concluded that the adrenergic tonus affecting the dorsal aortic blood pressure in resting cod that have recovered for 24 h following surgery is due solely to an adrenergic nervous tone.

scholarly journals 3-Deazaadenosine mitigates arterial remodeling and hypertension in hyperhomocysteinemic mice

2006 ◽  
Vol 291 (5) ◽  
pp. L905-L911 ◽  
Author(s):  
Alexander V. Ovechkin ◽  
Neetu Tyagi ◽  
Utpal Sen ◽  
David Lominadze ◽  
Mesia M. Steed ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Arterial Hypertension ◽  
Wall Thickness ◽  
Connexin 43 ◽  
Aortic Wall ◽  
Arterial Remodeling ◽  
Control Groups ◽  
Aortic Blood ◽  
Aortic Blood Pressure

Chronic hyperhomocysteinemia (HHcy) is an important factor in development of arterial hypertension. HHcy is associated with activation of matrix metalloproteinases (MMPs); however, it is unclear whether HHcy-dependent extracellular matrix (ECM) accumulation plays a role in arterial hypertrophy and hypertension. We tested the hypothesis that in HHcy the mechanism of arterial hypertension involves arterial dysfunction in response to ECM accumulation between endothelial and arterial smooth muscle cells and subsequent endothelium-myocyte (E-M) uncoupling. To decrease plasma Hcy, dietary supplementation with 3-deazaadenosine (DZA), the S-adenosylhomocysteine hydrolase inhibitor, was administered to cystathionine β-synthase (CBS) knockout (KO) mice. Mice were grouped as follows: wild type (WT; control), WT+DZA, CBSKO, and CBSKO+DZA ( n = 4/group). Mean aortic blood pressure and heart rate were monitored in real time with a telemetric system before, during, and after DZA treatment (6 wk total). In vivo aorta function and morphology were analyzed by M-mode and Doppler echocardiography in anesthetized mice. Aorta MMP activity in unfixed cryostat sections was measured with DQ gelatin. Aorta MMP-2, MMP-9, and connexin 43 expression were measured by RT-PCR and Western blot analyses, respectively. HHcy caused increased aortic blood pressure and resistance, tachycardia, and increased wall thickness and ECM accumulation in aortic wall vs. control groups. There was a linear correlation between aortic wall thickness and plasma Hcy levels. MMP-2, MMP-9, and connexin 43 expression were increased in HHcy. In the CBSKO+DZA group, aortic blood pressure and levels of MMP and connexin 43 were close to those found in control groups. However, removal of DZA reversed the aortic lumen-to-wall thickness ratio in CBSKO mice, suggesting, in part, a role of vascular remodeling in the increase in blood pressure in HHcy. The results show that arterial hypertension in HHcy mice is, in part, associated with arterial remodeling and E-M uncoupling in response to MMP activation.

Relations Between the Timing of the Second Heart Sound and Aortic Blood Pressure

2008 ◽  
Vol 55 (4) ◽  
pp. 1291-1297 ◽  
Author(s):  
Xin-Yu Zhang ◽  
E. MacPherson ◽  
Yuan-Ting Zhang
Keyword(s):  
Blood Pressure ◽  
Heart Sound ◽  
Aortic Blood ◽  
Aortic Blood Pressure ◽  
Second Heart Sound

Volume status and arterial blood pressures are associated with arterial stiffness in hemodialysis patients

2018 ◽  
Vol 41 (7) ◽  
pp. 378-384 ◽  
Author(s):  
Alper Erdan ◽  
Abdullah Ozkok ◽  
Nadir Alpay ◽  
Vakur Akkaya ◽  
Alaattin Yildiz
Keyword(s):  
Blood Pressure ◽  
Arterial Stiffness ◽  
Pulse Wave Velocity ◽  
Wave Velocity ◽  
Pulse Pressure ◽  
Pulse Wave ◽  
Augmentation Index ◽  
Mean Blood Pressure ◽  
Aortic Blood ◽  
Aortic Blood Pressure

Background: Arterial stiffness is a strong predictor of mortality in hemodialysis patients. In this study, we aimed to investigate possible relations of arterial stiffness with volume status determined by bioimpedance analysis and aortic blood pressure parameters. Also, effects of a single hemodialysis session on these parameters were studied. Methods: A total of 75 hemodialysis patients (M/F: 43/32; mean age: 53 ± 17) were enrolled. Carotid-femoral pulse wave velocity, augmentation index, and aortic pulse pressure were measured by applanation tonometry before and after hemodialysis. Extracellular fluid and total body fluid volumes were determined by bioimpedance analysis. Results: Carotid-femoral pulse wave velocity (9.30 ± 3.30 vs 7.59 ± 2.66 m/s, p < 0.001), augmentation index (24.52 ± 9.42 vs 20.28 ± 10.19, p < 0.001), and aortic pulse pressure (38 ± 14 vs 29 ± 8 mmHg, p < 0.001) significantly decreased after hemodialysis. Pre-dialysis carotid-femoral pulse wave velocity was associated with age (r2 = 0.15, p = 0.01), total cholesterol (r2 = 0.06, p = 0.02), peripheral mean blood pressure (r2 = 0.10, p = 0.005), aortic-mean blood pressure (r2 = 0.06, p = 0.02), aortic pulse pressure (r2 = 0.14, p = 0.001), and extracellular fluid/total body fluid (r2 = 0.30, p < 0.0001). Pre-dialysis augmentation index was associated with total cholesterol (r2 = 0.06, p = 0,02), aortic-mean blood pressure (r2 = 0.16, p < 0.001), and aortic pulse pressure (r2 = 0.22, p < 0.001). Δcarotid-femoral pulse wave velocity was associated with Δaortic-mean blood pressure (r2 = 0.06, p = 0.02) and inversely correlated with baseline carotid-femoral pulse wave velocity (r2 = 0.29, p < 0.001). Pre-dialysis Δaugmentation index was significantly associated with Δaortic-mean blood pressure (r2 = 0.09, p = 0.009) and Δaortic pulse pressure (r2 = 0.06, p = 0.03) and inversely associated with baseline augmentation index (r2 = 0.14, p = 0.001). In multiple linear regression analysis (adjusted R2 = 0.46, p < 0.001) to determine the factors predicting Log carotid-femoral pulse wave velocity, extracellular fluid/total body fluid and peripheral mean blood pressure significantly predicted Log carotid-femoral pulse wave velocity (p = 0.001 and p = 0.006, respectively). Conclusion: Carotid-femoral pulse wave velocity, augmentation index, and aortic pulse pressure significantly decreased after hemodialysis. Arterial stiffness was associated with both peripheral and aortic blood pressure. Furthermore, reduction in arterial stiffness parameters was related to reduction in aortic blood pressure. Pre-dialysis carotid-femoral pulse wave velocity was associated with volume status determined by bioimpedance analysis. Volume control may improve not only the aortic blood pressure measurements but also arterial stiffness in hemodialysis patients.

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