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Yao J, Sprick JD, Jeong J, Park J, Reiter DA. Differences in peripheral microcirculatory blood flow regulation in chronic kidney disease based on wavelet analysis of resting near-infrared spectroscopy. Microvasc Res 2024; 151:104624. [PMID: 37926135 PMCID: PMC11018197 DOI: 10.1016/j.mvr.2023.104624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 10/13/2023] [Accepted: 11/01/2023] [Indexed: 11/07/2023]
Abstract
Vascular impairment is closely related to increased mortality in chronic kidney disease (CKD). The objective of this study was to assess impairments in the regulation of peripheral microvascular perfusion in patients with CKD based on time-frequency spectral analysis of resting near-infrared spectroscopy (NIRS) signals. Total hemoglobin (tHb) concentration and tissue saturation index (TSI) signals were collected using NIRS for a continuous 5 mins at 10 Hz from the forearm of 55 participants (34 CKD including 5 with end-stage renal disease, and 21 age-matched control). Continuous wavelet transform-based spectral analysis was used to quantify the spectral amplitude within five pre-defined frequency intervals (I, 0.0095-0.021 Hz; II, 0.021-0.052 Hz; III, 0.052-0.145 Hz; IV, 0.145-0.6 Hz and V, 0.6-2.0 Hz), representing endothelial, neurogenic, myogenic, respiratory and heartbeat activity, respectively. CKD patients showed lower tHb average spectral amplitude within the neurogenic frequency interval compared with controls (p = 0.014), consistent with an increased sympathetic outflow observed in CKD. CKD patients also showed lower TSI average spectral amplitude within the endothelial frequency interval compared with controls (p = 0.046), consistent with a reduced endothelial function in CKD. These findings demonstrate the potential of wavelet analysis of NIRS to provide complementary information on peripheral microvascular regulation in CKD.
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Affiliation(s)
- Jingting Yao
- Department of Radiology and Imaging Science, Emory University, Atlanta, GA, United States; Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States
| | - Justin D Sprick
- Department of Kinesiology, Health Promotion, and Recreation, University of North Texas, Denton, TX, United States
| | - Jinhee Jeong
- Division of Renal Medicine, Emory University, Atlanta, GA, United States; Atlanta Veterans Affairs Medical Center, Decatur, GA, United States
| | - Jeanie Park
- Division of Renal Medicine, Emory University, Atlanta, GA, United States; Atlanta Veterans Affairs Medical Center, Decatur, GA, United States
| | - David A Reiter
- Department of Radiology and Imaging Science, Emory University, Atlanta, GA, United States; Department of Orthopedics, Emory University, Atlanta, GA, United States; Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, United States.
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2
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Amendola C, Buttafava M, Carteano T, Contini L, Cortese L, Durduran T, Frabasile L, Guadagno CN, Karadeinz U, Lacerenza M, Mesquida J, Parsa S, Re R, Sanoja Garcia D, Konugolu Venkata Sekar S, Spinelli L, Torricelli A, Tosi A, Weigel UM, Yaqub MA, Zanoletti M, Contini D. Assessment of power spectral density of microvascular hemodynamics in skeletal muscles at very low and low-frequency via near-infrared diffuse optical spectroscopies. BIOMEDICAL OPTICS EXPRESS 2023; 14:5994-6015. [PMID: 38021143 PMCID: PMC10659778 DOI: 10.1364/boe.502618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Revised: 10/10/2023] [Accepted: 10/16/2023] [Indexed: 12/01/2023]
Abstract
In this work, we used a hybrid time domain near-infrared spectroscopy (TD-NIRS) and diffuse correlation spectroscopy (DCS) device to retrieve hemoglobin and blood flow oscillations of skeletal muscle microvasculature. We focused on very low (VLF) and low-frequency (LF) oscillations (i.e., frequency lower than 0.145 Hz), that are related to myogenic, neurogenic and endothelial activities. We measured power spectral density (PSD) of blood flow and hemoglobin concentration in four muscles (thenar eminence, plantar fascia, sternocleidomastoid and forearm) of 14 healthy volunteers to highlight possible differences in microvascular hemodynamic oscillations. We observed larger PSDs for blood flow compared to hemoglobin concentration, in particular in case of distal muscles (i.e., thenar eminence and plantar fascia). Finally, we compared the PSDs measured on the thenar eminence of healthy subjects with the ones measured on a septic patient in the intensive care unit: lower power in the endothelial-dependent frequency band, and larger power in the myogenic ones were observed in the septic patient, in accordance with previous works based on laser doppler flowmetry.
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Affiliation(s)
| | | | | | | | - Lorenzo Cortese
- ICFO - Institut de Ciències Fotòniques, The Barcelona Institute of Science and Technology, Castelldefels (Barcelona), Spain
| | - Turgut Durduran
- ICFO - Institut de Ciències Fotòniques, The Barcelona Institute of Science and Technology, Castelldefels (Barcelona), Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain
| | | | - Claudia Nunzia Guadagno
- BioPixS Ltd – Biophotonics Standards, IPIC, Tyndall National Institute, Lee Maltings Complex, Cork, Ireland
| | - Umut Karadeinz
- ICFO - Institut de Ciències Fotòniques, The Barcelona Institute of Science and Technology, Castelldefels (Barcelona), Spain
| | | | - Jaume Mesquida
- Critical Care Department, Parc Taulí Hospital Universitari. Institut D’Investigació i Innovació Parc Taulí I3PT, Sabadell, Spain
| | | | - Rebecca Re
- Dipartimento di Fisica, Politecnico di Milano, Milan, Italy
- Istituto di Fotonica e Nanotecnologie, Consiglio Nazionale delle Ricerche, Milano, Italy
| | | | | | - Lorenzo Spinelli
- Istituto di Fotonica e Nanotecnologie, Consiglio Nazionale delle Ricerche, Milano, Italy
| | - Alessandro Torricelli
- Dipartimento di Fisica, Politecnico di Milano, Milan, Italy
- Istituto di Fotonica e Nanotecnologie, Consiglio Nazionale delle Ricerche, Milano, Italy
| | - Alberto Tosi
- Politecnico di Milano, Dipartimento di Elettronica, Informazione e Bioingegneria, Milan, Italy
| | - Udo M. Weigel
- HemoPhotonics S.L., Castelldefels, (Barcelona), Spain
| | - M. Atif Yaqub
- ICFO - Institut de Ciències Fotòniques, The Barcelona Institute of Science and Technology, Castelldefels (Barcelona), Spain
| | - Marta Zanoletti
- ICFO - Institut de Ciències Fotòniques, The Barcelona Institute of Science and Technology, Castelldefels (Barcelona), Spain
| | - Davide Contini
- Dipartimento di Fisica, Politecnico di Milano, Milan, Italy
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Kralj L, Lenasi H. Wavelet analysis of laser Doppler microcirculatory signals: Current applications and limitations. Front Physiol 2023; 13:1076445. [PMID: 36741808 PMCID: PMC9895103 DOI: 10.3389/fphys.2022.1076445] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Accepted: 12/28/2022] [Indexed: 01/21/2023] Open
Abstract
Laser Doppler flowmetry (LDF) has long been considered a gold standard for non-invasive assessment of skin microvascular function. Due to the laser Doppler (LD) microcirculatory signal's complex biological and physiological context, using spectral analysis is advisable to extract as many of the signal's properties as feasible. Spectral analysis can be performed using either a classical Fourier transform (FT) technique, which has the disadvantage of not being able to localize a signal in time, or wavelet analysis (WA), which provides both the time and frequency localization of the inspected signal. So far, WA of LD microcirculatory signals has revealed five characteristic frequency intervals, ranging from 0.005 to 2 Hz, each of which being related to a specific physiological influence modulating skin microcirculatory response, providing for a more thorough analysis of the signals measured in healthy and diseased individuals. Even though WA is a valuable tool for analyzing and evaluating LDF-measured microcirculatory signals, limitations remain, resulting in a lack of analytical standardization. As a more accurate assessment of human skin microcirculation may better enhance the prognosis of diseases marked by microvascular dysfunction, searching for improvements to the WA method is crucial from the clinical point of view. Accordingly, we have summarized and discussed WA application and its limitations when evaluating LD microcirculatory signals, and presented insight into possible future improvements. We adopted a novel strategy when presenting the findings of recent studies using WA by focusing on frequency intervals to contrast the findings of the various studies undertaken thus far and highlight their disparities.
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Affiliation(s)
- Lana Kralj
- Institute of Physiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Helena Lenasi
- Institute of Physiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia,*Correspondence: Helena Lenasi,
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Martini R, Bagno A. The wavelet analysis for the assessment of microvascular function with the laser Doppler fluxmetry over the last 20 years. Looking for hidden informations. Clin Hemorheol Microcirc 2018; 70:213-229. [DOI: 10.3233/ch-189903] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Romeo Martini
- Department of Cardio-Thorax and Vascular Sciences, Unit of Angiology, Azienda Ospedaliera Universitaria di Padova, Italy
| | - Andrea Bagno
- Department of Industrial Engineering, Università di Padova, Italy
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Yuan X, Wu Q, Shang F, Li B, Liu M, Wang B, Sheng Y, Zhang H, Xiu R. A comparison of the cutaneous microvascular properties of the Spontaneously Hypertensive and the Wistar-Kyoto rats by Spectral analysis of Laser Doppler. Clin Exp Hypertens 2018; 41:342-352. [PMID: 29939761 DOI: 10.1080/10641963.2018.1481424] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
This work was aimed to study skin blood perfusion, vasomotion and vascular responses of the Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) in different stages of age using spectral. Laser-Doppler flowmetry (LDF) was used to examine the ears and limbs of WKY (12 and 48 weeks old) and SHR (12 and 48 weeks old). The skin blood flow oscillations (SBFOs) were studied by wavelet spectral analysis of LDF tracings. Then, we observed that old groups showed decreased perfusion and SBFO in the ears of both SHR and WKY. The SHR showed obviously lower postocclusive reactive hypera (PORH) ratio at the same age. A decreased peak-time occurred in the SHR of old age group. After PORH test, a statistically significant increase was observed within all subintervals in the absolute amplitude of 12-week WKY and only within IV and III subintervals in the absolute amplitude of 12-week SHR. But, the absolute amplitude of 48-week WKY and SHR showed no statistically significant increase within all subintervals. Results indicated that local regulating function of peripheral vascular was impaired in rat with hypertension and aging. Abbreviations LDF: Laser-Doppler flowmetry; SBF: Skin blood flow; SBFO: Skin blood flow oscillation; PORH: Postocclusive reactive hyperemia; SHR: Spontaneously hypertensive rats; WKY: Wistar-Kyoto rats; LDF: Laser-Doppler flowmetry; LDI: Laser Doppler Imaging; BP: Blood pressure.
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Affiliation(s)
- Xiaochen Yuan
- a Key Laboratory for Microcirculation , Ministry of Health.,b Institute of Microcirculation , Chinese Academy Medical Sciences & Pecking Union Medical College , Beijing , China
| | - Qingbin Wu
- a Key Laboratory for Microcirculation , Ministry of Health.,b Institute of Microcirculation , Chinese Academy Medical Sciences & Pecking Union Medical College , Beijing , China
| | - Fei Shang
- a Key Laboratory for Microcirculation , Ministry of Health.,b Institute of Microcirculation , Chinese Academy Medical Sciences & Pecking Union Medical College , Beijing , China
| | - Bingwei Li
- a Key Laboratory for Microcirculation , Ministry of Health.,b Institute of Microcirculation , Chinese Academy Medical Sciences & Pecking Union Medical College , Beijing , China
| | - Mingming Liu
- a Key Laboratory for Microcirculation , Ministry of Health.,b Institute of Microcirculation , Chinese Academy Medical Sciences & Pecking Union Medical College , Beijing , China
| | - Bing Wang
- a Key Laboratory for Microcirculation , Ministry of Health.,b Institute of Microcirculation , Chinese Academy Medical Sciences & Pecking Union Medical College , Beijing , China
| | - Youming Sheng
- a Key Laboratory for Microcirculation , Ministry of Health.,b Institute of Microcirculation , Chinese Academy Medical Sciences & Pecking Union Medical College , Beijing , China
| | - Honggang Zhang
- a Key Laboratory for Microcirculation , Ministry of Health.,b Institute of Microcirculation , Chinese Academy Medical Sciences & Pecking Union Medical College , Beijing , China
| | - Ruijuan Xiu
- a Key Laboratory for Microcirculation , Ministry of Health.,b Institute of Microcirculation , Chinese Academy Medical Sciences & Pecking Union Medical College , Beijing , China
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Östlund Papadogeorgos N, Jörneskog G, Bengtsson M, Kahan T, Kalani M. Severely impaired microvascular reactivity in diabetic patients with an acute coronary syndrome. Cardiovasc Diabetol 2016; 15:66. [PMID: 27095564 PMCID: PMC4837627 DOI: 10.1186/s12933-016-0385-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Accepted: 04/07/2016] [Indexed: 12/16/2022] Open
Abstract
Background Microvascular function is impaired in patients with stable coronary artery disease. The aim was to study microvascular function in patients with diabetes and acute coronary syndrome (ACS). Methods Microvascular function was evaluated in 83 patients by laser Doppler fluxmetry (LDF) [PU; perfusion unit, median (interquartile range)] measuring resting LDF and peak LDF following a six min heating of the skin to 44 °C at the foot, respectively. All patients with ACS and without previously known diabetes underwent oral glucose tolerance test. Thirty-nine patients with type 2 diabetes mellitus free from coronary artery disease served as controls. Results Peak LDF was significantly (P = 0.03) lower in patients with ACS and diabetes (n = 22; 72 (52)) and diabetes without coronary artery disease (n = 39; 69 (51)) as compared to patients with ACS without diabetes (n = 46; 97 (60)), and patients without ACS (n = 15; 140 (121)), respectively. Patients with ACS (n = 68) had significantly (P = 0.04) lower peak LDF (92 (49)) as compared to patients without ACS (n = 15) (140 (121)). Conclusion Microvascular reactivity is severely impaired in patients with diabetes and ACS. Diabetes has a major influence on microvascular function in patients with coronary artery disease.
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Affiliation(s)
| | - Gun Jörneskog
- Department of Clinical Sciences, Karolinska Institutet, Danderyd Hospital, Stockholm, Sweden
| | - Mattias Bengtsson
- Department of Clinical Sciences, Karolinska Institutet, Danderyd Hospital, Stockholm, Sweden
| | - Thomas Kahan
- Department of Clinical Sciences, Karolinska Institutet, Danderyd Hospital, Stockholm, Sweden
| | - Majid Kalani
- Department of Clinical Sciences, Karolinska Institutet, Danderyd Hospital, Stockholm, Sweden
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Tikhonova IV, Tankanag AV, Chemeris NK. Age-related changes of skin blood flow during postocclusive reactive hyperemia in human. Skin Res Technol 2012; 19:e174-81. [DOI: 10.1111/j.1600-0846.2012.00624.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/26/2012] [Indexed: 12/01/2022]
Affiliation(s)
- Irina V. Tikhonova
- Institute of Cell Biophysics; Russian Academy of Sciences; Institutskaya st. 3; Pushchino; Moscow Region; 142290; Russia
| | - Arina V. Tankanag
- Institute of Cell Biophysics; Russian Academy of Sciences; Institutskaya st. 3; Pushchino; Moscow Region; 142290; Russia
| | - Nikolay K. Chemeris
- Institute of Cell Biophysics; Russian Academy of Sciences; Institutskaya st. 3; Pushchino; Moscow Region; 142290; Russia
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8
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Jochum T, Weissenfels M, Seeck A, Schulz S, Boettger MK, Voss A, Bär KJ. Endothelial dysfunction during acute alcohol withdrawal syndrome. Drug Alcohol Depend 2011; 119:113-22. [PMID: 21719213 DOI: 10.1016/j.drugalcdep.2011.06.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2011] [Revised: 05/29/2011] [Accepted: 06/02/2011] [Indexed: 01/20/2023]
Abstract
BACKGROUND Endothelial dysfunction (EF) is a central phenomenon in a variety of conditions associated with increased cardiovascular morbidity. Here, we investigated EF during acute alcohol withdrawal syndrome before and 24h after medication. We aimed to analyze microcirculation, applying the post-occlusive reactive hyperemia (PORH) test and spectral analysis of skin vasomotion as markers of EF. Additionally, we explored whether segmentation of spectral analysis data may disclose more detailed information on dynamic blood flow behavior. METHODS We investigated 30 unmedicated patients during acute alcohol withdrawal syndrome and matched controls. Patients were reinvestigated after 24h when half of them had been treated with clomethiazole. Capillary blood flow was assessed on the right forearm after compression of the brachial artery. Parameters of PORH such as time to peak (TP), slope and PORH indices were calculated. Spectral analysis was performed in order to study five different frequency bands. Withdrawal symptoms were quantified by means of the alcohol withdrawal scale (AW scale). RESULTS We observed a blunted hyperemic response in patients after occlusion of the brachial artery indicated by significantly increased TP and decreased PORH indices. In contrast, vasomotion as investigated by spectral analysis was not altered. Segmentation analysis revealed some alterations in the cardiac band at rest, and indicated differences between treated and untreated patients after 24h. CONCLUSION Our results suggest peripheral endothelial dysfunction in patients during acute alcohol withdrawal. No major influence of treatment was observed. Future studies need to address the relation of EF to cardiac morbidity during alcohol withdrawal.
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Affiliation(s)
- Thomas Jochum
- Pain and Autonomics - Integrative Research (PAIR), Department of Psychiatry and Psychotherapy, University Hospital, Jena 07743, Germany
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Fractal scaling of laser Doppler flowmetry time series in patients with essential hypertension. Microvasc Res 2011; 82:291-5. [PMID: 21854788 DOI: 10.1016/j.mvr.2011.07.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2011] [Revised: 07/29/2011] [Accepted: 07/31/2011] [Indexed: 11/22/2022]
Abstract
The full diagnostic potential of the fractal complexity measure, α, of detrended fluctuation analysis (DFA) has not been realized yet. To reveal the impaired mechanisms in the blood flow regulation in patients with essential hypertension (EHT), we studied the laser Doppler flowmetry (LDF) time series by applying DFA. Forearm microvascular blood flow was measured by LDF during supine rest. After a 15 min baseline recording, microvascular response to thermal hyperemia was measured over 30 min. We found three distinct scaling regions; corresponding to the integration of local mechanisms, cardiac effect on local blood flow, and the coupling of extrinsic factors (cardiac and respiratory) to local blood flow by myogenic mechanism. In the control group, local scaling exponent, α(L)=0.96 ± 0.08, did not change but cardiac scaling exponent, α(C)=1.53 ± 0.05, for baseline signal was increased to α(CT)=1.73 ± 0.10 and cardio-respiratory scaling exponent, α(CR)=0.73 ± 0.19, was decreased to α(CRT)=0.24 ± 0.06 during vasodilatation in response to local heating. However, we found significantly different scaling exponents, α(LT)<1, α(CT) ≥ α(C)<1.5 and α(CR) ≈ α(CRT)>0.5 in patients with EHT. Our findings suggest that the local regulatory and the cushioning peripheral vascular functions are impaired in patients with EHT, and vascular/microvascular pathology can be evaluated by applying DFA to LDF signal.
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10
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Israel AK, Seeck A, Boettger MK, Rachow T, Berger S, Voss A, Bär KJ. Peripheral endothelial dysfunction in patients suffering from acute schizophrenia: a potential marker for cardiovascular morbidity? Schizophr Res 2011; 128:44-50. [PMID: 21371864 DOI: 10.1016/j.schres.2011.02.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2010] [Revised: 01/28/2011] [Accepted: 02/05/2011] [Indexed: 11/16/2022]
Abstract
Patients suffering from schizophrenia have an increased standardized ratio for cardiovascular mortality compared to the general population. Endothelial function was identified as a prominent parameter for cardiac risk stratification in patients with heart disease. Here, we aimed to analyze the reactivity of the microcirculation applying the post-occlusive reactive hyperemia (PORH) test and spectral analysis of skin vasomotion as markers of endothelial function. We investigated 21 unmedicated patients suffering from paranoid schizophrenia as well as 21 matched controls. The capillary blood flow was assessed on the right forearm after compression of the brachial artery. Parameters of PORH such as time to peak (TP) or PORH index were calculated. In addition, spectral analysis of skin vasomotion was performed and five frequency bands (endothelial, sympathetic, vascular myogenic, respiratory and heart beat activity) were studied. Psychotic symptoms were quantified using the Positive and Negative Syndrome Scale (PANSS) and correlated to the parameters obtained. We report a blunted hyperemic response in patients after occlusion of the brachial artery indicated by significantly increased TP and decreased PORH indices. In contrast, vasomotion as investigated by spectral analysis of skin flow was rather sparsely altered showing differences at rest for the sympathetic and cardiac components only. Our results are suggestive of peripheral endothelial dysfunction in unmedicated patients suffering from schizophrenia. Future, prospective studies should address the relation of endothelial dysfunction to cardiac morbidity in patients with schizophrenia.
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Esen F, Aydın GS, Esen H. Detrended fluctuation analysis of laser Doppler flowmetry time series. Microvasc Res 2009; 78:314-8. [DOI: 10.1016/j.mvr.2009.07.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2009] [Revised: 06/26/2009] [Accepted: 07/22/2009] [Indexed: 10/20/2022]
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12
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Humeau A, Buard B, Chapeau-Blondeau F, Rousseau D, Mahe G, Abraham P. Multifractal analysis of central (electrocardiography) and peripheral (laser Doppler flowmetry) cardiovascular time series from healthy human subjects. Physiol Meas 2009; 30:617-29. [DOI: 10.1088/0967-3334/30/7/007] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Stefanovska A. Dynamics of blood oxygenation gives better insight into tissue hypoxia than averaged values. Am J Physiol Heart Circ Physiol 2009; 296:H1224-6. [PMID: 19346459 PMCID: PMC2685328 DOI: 10.1152/ajpheart.00314.2009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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14
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Abstract
The pulse transit time (PTT) of a wave over a specified distance along a blood vessel provides a simple non-invasive index that can be used for the evaluation of arterial distensibility. Current methods of measuring the PTT determine the propagation times of pulses only in the larger arteries. We have evaluated the pulse arrival time (PAT) to the capillary bed, through the microcirculation, and have investigated its relationship to the arterial PAT to a fingertip. To do so, we detected cardiac-induced pulse waves in skin microcirculation using laser Doppler flowmetry (LDF). Using the ECG as a reference, PATs to the microcirculation were measured on the four extremities of 108 healthy subjects. Simultaneously, PATs to the radial artery of the left index finger were obtained from blood pressure recordings using a piezoelectric sensor. Both PATs correlate in similar ways with heart rate and age. That to the microcirculation is shown to be sensitive to local changes in skin perfusion induced by cooling. We introduce a measure for the PTT through the microcirculation. We conclude that a combination of LDF and pressure measurements enables simultaneous characterization of the states of the macro and microvasculature. Information about the microcirculation, including an assessment of endothelial function, may be obtained from the responses to perturbations in skin perfusion, such as temperature stress or vasoactive substances.
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Affiliation(s)
- Alan Bernjak
- Faculty of Electrical Engineering, University of Ljubljana, Trzaska 25, 1000 Ljubljana, Slovenia. Physics Department, Lancaster University, LA1 4YB, UK
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Bernjak A, Clarkson P, McClintock P, Stefanovska A. Low-frequency blood flow oscillations in congestive heart failure and after beta1-blockade treatment. Microvasc Res 2008; 76:224-32. [PMID: 18721820 PMCID: PMC2666799 DOI: 10.1016/j.mvr.2008.07.006] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2008] [Revised: 07/22/2008] [Accepted: 07/23/2008] [Indexed: 11/20/2022]
Abstract
Laser Doppler flowmetry (LDF) of forearm skin blood flow, combined with iontophoretically-administered acetylcholine and sodium nitroprusside and wavelet spectral analysis, was used for noninvasive evaluation of endothelial function in 17 patients newly diagnosed with New York Heart Association class II-III congestive heart failure (CHF). After 20+/-10 weeks' treatment with a beta(1)-blocker (Bisoprolol), the measurements were repeated. Measurements were also made on an age- and sex-matched group of healthy controls (HC). In each case data were recorded for 30 min. In HC, the difference in absolute spectral amplitude of LDF oscillations between the two vasodilators manifests in the frequency interval 0.005-0.0095 Hz (p<0.01); this difference is initially absent in patients with CHF, but appears following the beta(1)-blocker treatment (p<0.01). For HC, the difference between the two vasodilators also manifests in normalised spectral amplitude in 0.0095-0.021 Hz (p<0.05). This latter difference is absent in CHF patients and is unchanged by treatment with beta(1)-blockers. It is concluded that there are two oscillatory skin blood flow components associated with endothelial function. Both are reduced in CHF. Activity in the lower frequency interval is restored by beta(1)-blocker treatment, confirming the association between CHF and endothelial dysfunction but suggesting the involvement of two distinct mechanisms.
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Affiliation(s)
- A. Bernjak
- Faculty of Electrical Engineering, University of Ljubljana, Slovenia
- Physics Department, Lancaster University, LA1 4YB, UK
| | - P.B.M. Clarkson
- Cardiology Department, Royal Lancaster Infirmary, LA1 4RP, UK
| | | | - A. Stefanovska
- Faculty of Electrical Engineering, University of Ljubljana, Slovenia
- Physics Department, Lancaster University, LA1 4YB, UK
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Stefanovska A. Commentary on Viewpoint: The human cutaneous circulation as a model of generalized microvascular function. J Appl Physiol (1985) 2008; 105:387; author reply 389. [DOI: 10.1152/japplphysiol.90324.2008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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