Relationship of Laser-Doppler-Flow and coronary perfusion and a concise update on the importance of coronary microcirculation in donor heart machine perfusion

2021 ◽  
Vol 79 (1) ◽  
pp. 121-128
Author(s):  
Lars Saemann ◽  
Anne Großkopf ◽  
Fabio Hoorn ◽  
Gábor Veres ◽  
Yuxing Guo ◽  
...  
Keyword(s):  
Laser Doppler ◽  
Control Group ◽  
Coronary Perfusion ◽  
Machine Perfusion ◽  
Donor Heart ◽  
Doppler Flowmetry ◽  
Laser Doppler Flow ◽  
Doppler Flow ◽  
Ischemia Group ◽  
Coronary Microvascular Function

BACKGROUND: Machine perfusion (MP) is a novel method for donor heart preservation. The coronary microvascular function is important for the transplantation outcome. However, current research on MP in heart transplantation focuses mainly on contractile function. OBJECTIVE: We aim to present the application of Laser-Doppler-Flowmetry to investigate coronary microvascular function during MP. Furthermore, we will discuss the importance of microcirculation monitoring for perfusion-associated studies in HTx research. METHODS: Porcine hearts were cardioplegically arrested and harvested (Control group, N = 4). In an ischemia group (N = 5), we induced global ischemia of the animal by the termination of mechanical ventilation before harvesting. All hearts were mounted on an MP system for blood perfusion. After 90 minutes, we evaluated the effect of coronary perfusion pressures from 20 to 100 mmHg while coronary laser-doppler-flow (LDF) was measured. RESULTS: Ischemic hearts showed a significantly decreased relative LDF compared to control hearts (1.07±0.06 vs. 1.47±0.15; p = 0.034). In the control group, the coronary flow was significantly lower at 100 mmHg of perfusion pressure than in the ischemia group (895±66 ml vs. 1112±32 ml; p = 0.016). CONCLUSIONS: Laser-Doppler-Flowmetry is able to reveal coronary microvascular dysfunction during machine perfusion of hearts and is therefore of substantial interest for perfusion-associated research in heart transplantation.

In Vivo Effects of Dexmedetomidine on Laser-Doppler Flow and Pial Arteriolar Diameter 

1998 ◽  
Vol 88 (2) ◽  
pp. 429-439 ◽  
Author(s):  
Pragati Ganjoo ◽  
Neil E. Farber ◽  
Antal Hudetz ◽  
Jeremy J. Smith ◽  
Enric Samso ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Measurement Techniques ◽  
Laser Doppler ◽  
Doppler Flowmetry ◽  
Laser Doppler Flow ◽  
Doppler Flow ◽  
The Mean ◽  
Arteriolar Diameter

Background The alpha2-adrenergic agonist dexmedetomidine alters global cerebral blood flow (CBF). However, few studies have investigated the action of dexmedetomidine on the cerebral microcirculation. This investigation examined the effects of dexmedetomidine on (1) regional CBF in the rat cerebral cortex using laser-Doppler flowmetry and (2) on pial arteriolar diameter. Methods Halothane-anesthetized rats were fitted with instruments to measure CBF as determined by laser-Doppler flow (CBFldf) or to measure pial arteriolar diameter by preparing a cranial hollow deepened until a translucent plate of skull remained, thereby maintaining the integrity of the cranial vault. In both groups, 20 microg/kg dexmedetomidine was infused intravenously. Thirty minutes later, the mean arterial pressure was restored to control values with an infusion of phenylephrine (0.5 to 5 microg/kg/min). Results Administration of dexmedetomidine was associated with decreases in end-tidal and arterial carbon dioxide. The CBFldf and pial arteriolar diameter were measured during normocapnia (controlled carbon dioxide) and during dexmedetomidine-induced hypocapnia. Intravenous administration of dexmedetomidine significantly decreased systemic arterial pressure concurrent with a decrease in CBFldf (22% in normocapnic animals, 36% in hypocapnic animals). Restoration of mean arterial pressure increased CBFldf in normocapnic but not in hypocapnic animals. Similarly, dexmedetomidine significantly reduced pial vessel diameter in both normocapnic (9%) and hypocapnic animals (17%). However, vessel diameters remained decreased in the normocapnic and hypocapnic animals after the mean arterial pressure was restored. Conclusions These results suggest a modulation of cerebral vascular autoregulation by dexmedetomidine which may be mediated, in part, by alterations in carbon dioxide. Dexmedetomidine may have a direct action on the cerebral vessels to reduce the CBF during normo- or hypocapnia. The differences between CBFldf and pial arteriole responses to restoration of mean arterial pressure may reflect the difference in measurement techniques because laser-Doppler measurements reflect the net effect of several arterial segments on microvascular perfusion, whereas diameter measurements specifically examined individual pial arterioles, suggesting that dexmedetomidine vasoconstriction in the cerebral vasculature may be differentially and regionally mediated.

scholarly journals Metabolic and Hemodynamic Activation of Postischemic Rat Brain by Cortical Spreading Depression

1990 ◽  
Vol 10 (4) ◽  
pp. 564-571 ◽  
Author(s):  
M. Kocher
Keyword(s):  
Cortical Spreading Depression ◽  
Spreading Depression ◽  
Metabolic Response ◽  
Laser Doppler ◽  
Control Group ◽  
Partial Recovery ◽  
Adult Rats ◽  
Laser Doppler Flow ◽  
Doppler Flow ◽  
Neuronal Excitation

Following transient ischemia of the brain, the coupling between somatosensory activation and the hemodynamic-metabolic response is abolished for a certain period despite the partial recovery of somatosensory evoked responses. To determine whether this disturbance is due to alterations of the stimulus-induced neuronal excitation or to a breakdown of the coupling mechanisms, cortical spreading depression was used as a metabolic stimulus in rats before and after ischemia. Adult rats were subjected to 30 min of global forebrain ischemia and 3–6 h of recirculation. EEG, cortical direct current (DC) potential, and laser-Doppler flow were continuously recorded. Local CBF (LCBF), local CMRglc (LCMRglc), regional tissue contents of ATP, glucose, and lactate, and regional pH were determined by quantitative autoradiography, substrate-induced bioluminescence, and fluorometry. Amplitude and frequency of the DC shifts did not differ between groups. In control animals, spreading depression induced a 77% rise in cortical glucose consumption, a 66% rise in lactate content, and a drop in tissue pH of 0.3 unit. ATP and glucose contents were not depleted. During the passage of DC shifts, transient increases (<2 min) in laser-Doppler flow were observed, followed by a post-spreading depression hypoperfusion. A comparable although less expressed pattern of hemodynamic and metabolic changes was observed in the postischemic rats. Although baseline LCMRglc was depressed after ischemia, it was activated 47% during spreading depression. Lactate increased by 26%, pH decreased by 0.3 unit, and ATP and glucose remained unchanged. The extent of the transient increase in laser-Doppler flow did not differ from that of the control group, and a post–spreading depression hypoperfusion was also found. The results demonstrate that the postischemic brain may, although to a lesser degree, cover additional energy demands. The previously observed suppression of functional activation after ischemia is probably caused by both alterations in afferent synaptic transmission and subsequent neuronal excitation and the diminution of the metabolic response to a local stimulus as observed during spreading depression.

Evaluation of laser-Doppler flowmetry as a measure of tissue blood flow

1986 ◽  
Vol 61 (2) ◽  
pp. 666-672 ◽  
Author(s):  
G. J. Smits ◽  
R. J. Roman ◽  
J. H. Lombard
Keyword(s):  
Blood Flow ◽  
Laser Doppler Flowmetry ◽  
Electromagnetic Flowmeter ◽  
Laser Doppler ◽  
Tissue Blood Flow ◽  
Organ Blood Flow ◽  
Doppler Flowmetry ◽  
Laser Doppler Flow ◽  
Doppler Flow

In this study the technique of laser-Doppler flowmetry was evaluated for the measurement of tissue blood flow by comparing laser-Doppler flow (LDF) signal in the renal cortex, gracilis muscle, and cremaster muscle of anesthetized rats to whole-organ blood flow measured with an electromagnetic flowmeter or radioactive microspheres. In vitro, LDF signal was closely correlated (r = 0.99) to changes in erythrocyte velocity generated with a rotating wheel. Although individual LDF readings varied in situ, mean LDF signal calculated from multiple readings on the tissue surface were significantly correlated (r = 0.74–0.95) with tissue blood flows measured at various perfusion pressures. However, significant differences in the slope of the LDF signal vs. blood flow relationship were observed in different tissues and with different methods of measurement in the same tissue. This study indicates that mean laser-Doppler flow signal provides a good estimate of tissue blood flow, provided a sufficient number of points is scanned. However, there appears to be no universal calibration factor for the method.

scholarly journals Influence of the Endothelial Glycocalyx on Cerebral Blood Flow in Mice

2000 ◽  
Vol 20 (11) ◽  
pp. 1571-1578 ◽  
Author(s):  
J. Vogel ◽  
M. Sperandio ◽  
A.R. Pries ◽  
O. Linderkamp ◽  
P. Gaehtgens ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Laser Doppler Flowmetry ◽  
Laser Doppler ◽  
Endothelial Glycocalyx ◽  
Doppler Flowmetry ◽  
Laser Doppler Flow ◽  
Doppler Flow ◽  
Cerebral Capillaries ◽  
Saline Treatment

The endothelial surface layer (glycocalyx) of cerebral capillaries may increase resistance to blood flow. This hypothesis was investigated in mice by intravenous administration of heparinase (2500 IU/kg body weight in saline), which cleaves proteoglycan junctions of the glycocalyx. Morphology was investigated by transmission electron microscopy. Cerebral perfusion velocity was recorded before and during heparinase or saline treatment using laser–Doppler flowmetry. In addition, cerebral blood flow (CBF) was measured 10 minutes after heparinase or saline treatment using the iodo[14C]antipyrine method. Laser–Doppler flowmetry and CBF measurements were performed during normocapnia and severe hypercapnia (Pco2: 120 mm Hg). After heparinase, morphology showed a reduced thickness of the glycocalyx in cortical microvessels by 43% ( P < 0.05) compared with saline-treated controls. Under normocapnic conditions, a 15% ( P < 0.05) transient increase of cerebral flow velocity occurred 2.5 to 5 minutes after heparinase injection. Laser–Doppler flow and CBF returned to control values ten minutes after the injection. However, during severe hypercapnia, heparinase treatment resulted in a persisting increase in laser–Doppler flow (6%, P < 0.05) and CBF (30%, P < 0.05). These observations indicate the existence of a flow resistance in cerebral capillaries exerted by the glycocalyx. The transient nature of the CBF increase during normocapnia may be explained by a vascular compensation that is exhausted during severe hypercapnia.

scholarly journals Correlation of rheoencephalography and laser Doppler flow: a rat study

2019 ◽  
Vol 7 (1) ◽  
pp. 55-58 ◽  
Author(s):  
Michael Bodo ◽  
Ryan Sheppard ◽  
Aaron Hall ◽  
Martin Baruch ◽  
Melissa Laird ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Laser Doppler Flowmetry ◽  
Characteristic Curve ◽  
Laser Doppler ◽  
Doppler Flowmetry ◽  
Laser Doppler Flow ◽  
Doppler Flow ◽  
Cerebral Blood Flow Autoregulation ◽  
Rat Study

Abstract Measuring brain electrical impedance (rheoencephalography) is a potential technique for noninvasive, continuous neuro-monitoring of cerebral blood flow autoregulation in humans. In the present rat study, we compared changes in cerebral blood flow autoregulation during CO2 inhalation measured by rheoencephalography to changes measured by laser Doppler flowmetry, an invasive continuous monitoring modality. Our hypothesis was that both modalities would reflect cerebral blood flow autoregulation. Male Sprague-Dawley rats (n=28; 28 control and 82 CO2 challenges) were measured under anesthesia. The surgical preparation involved implantation of intracerebral REG electrodes and an LDF probe into the brain. Analog waveforms were stored in a computer. CO2 inhalation caused transient, simultaneous increases in the signals of both laser Doppler flow (171.99 ± 46.68 %) and rheoencephalography (329.88 ± 175.50%). These results showed a correlation between the two measured modalities; the area under the receiver operating characteristic curve was 0.8394. The similar results obtained by measurements made with laser Doppler flowmetry and rheoencephalography indicate that rheo-encephalography, like laser Doppler flowmetry, reflects cerebral blood flow autoregulation. Rheoencephalography therefore shows potential for use as a continuous neuro-monitoring technique.

The response of skin perfusion and of rheological and immunological variables to intravenous prostanoid administration in Raynaud’s phenomenon secondary to collagenosis

VASA ◽  
2005 ◽  
Vol 34 (4) ◽  
pp. 243-249 ◽  
Author(s):  
Drinda ◽  
Neumann ◽  
Pöhlmann ◽  
Vogelsang ◽  
Stein ◽  
...  
Keyword(s):  
Laser Doppler Flowmetry ◽  
Raynaud’S Phenomenon ◽  
Raynaud's Phenomenon ◽  
Plasma Viscosity ◽  
Laser Doppler ◽  
Erythrocyte Aggregation ◽  
Control Group ◽  
Long Term Effects ◽  
Doppler Flowmetry

Background: Prostanoids are used in the treatment of Raynaud’s phenomenon and acral perfusion disorders secondary to collagenosis. In subjective terms, intravenous administration of these agents produces success in more than 50% of patients. The therapeutic outcome of clinical administration of alprostadil or iloprost may vary from individual to individual. Patients and methods: The following variables were analysed in a cross-over study in 27 patients with collagenosis and Raynaud’s phenomenon: plasma viscosity and erythrocyte aggregation (rheological variables), partial pressure of oxygen and laser Doppler flowmetry in the finger region, and lymphocyte phenotyping and interleukin (IL) determinations (immunological variables). Results: Laser Doppler flowmetry revealed significant differences between patients with secondary Raynaud’s phenomenon and a control group of 25 healthy subjects. Laser Doppler readings did not change significantly as a result of the treatments. Therapy with iloprost produced a reduction in IL-1beta, L-selectin (CD 62 L) and IL-6. Conclusion: The change in immunological variables due to iloprost may explain the long-term effects of prostaglandins in the treatment of Raynaud’s phenomenon. From our results it is not possible to infer any preference for iloprost or alprostadil.

Laser Doppler Flow-Meter Assessment of Iontophoretically Applied Norepinephrine on Human Finger Skin Circulation

1986 ◽  
Vol 87 (5) ◽  
pp. 634-636 ◽  
Author(s):  
Lars Erik Lindblad ◽  
Lena Ekenvall ◽  
Klas Ancker ◽  
Håkan Rohman ◽  
P Åke Öberg
Keyword(s):  
Laser Doppler ◽  
Flow Meter ◽  
Laser Doppler Flow ◽  
Doppler Flow ◽  
Skin Circulation ◽  
Human Finger ◽  
Finger Skin

scholarly journals Efficacy of Laser Doppler Flowmetry, as a Diagnostic Tool in Assessing Pulp Vitality of Traumatised Teeth. A Split Mouth Clinical Study

2021 ◽  
Vol 11 (8) ◽  
pp. 801
Author(s):  
Ani Belcheva ◽  
Maria Shindova ◽  
Reem Hanna
Keyword(s):  
Laser Doppler Flowmetry ◽  
Test Group ◽  
Laser Doppler ◽  
Permanent Teeth ◽  
Control Group ◽  
Eligibility Criteria ◽  
Doppler Flowmetry ◽  
Registration Number ◽  
Pulp Vitality ◽  
And Control

Aim: This study aimed to evaluate the efficacy of laser Doppler flowmetry (LDF) in determining the changes in the pulpal blood flow (PBF) during post-traumatic period of the traumatised permanent teeth. Methods: 88 teeth of 44 patients (mean age 10.30 ± 2.38) were recruited according to the eligibility criteria and divided into two groups: test group (44 traumatised teeth) and control group (44 sound and healthy teeth). The measurement of PBF was performed, using a LDF monitor. Results: The analysis of the LDF outcomes in function of diagnosis indicated that the measurements of the traumatised teeth were significantly higher than those of non-traumatised teeth (p ˂ 0.05). Conclusions: LDF application provides dentists with fundamental benefits in terms of an early and precise investigation of PBF. In addition, LDF is a useful monitoring tool for revascularization of traumatised teeth and reliable objective diagnostic indicator of pulp vitality. Trial registration: ClinicalTrials.gov (Registration number: NCT04967456).

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