Validation of transit-time ultrasound flow probes to directly measure portal blood flow in conscious rats

1996 ◽  
Vol 271 (6) ◽  
pp. H2701-H2709 ◽  
Author(s):  
M. S. D'Almeida ◽  
S. Cailmail ◽  
D. Lebrec
Keyword(s):  
Blood Flow ◽  
Portal Vein ◽  
Direct Measurement ◽  
Transit Time ◽  
Portal Blood Flow ◽  
Portal Blood ◽  
Radioactive Microspheres ◽  
Portal Flow ◽  
Conscious Rats ◽  
The Relationship

Direct measurement of portal venous blood flow is technically difficult, yet crucial for accurate assessment of liver hemodynamic and metabolic functions. The aim of this investigation was to assess the feasibility of implanting transit-time ultra-sound (TTUS) perivascular flow probes on the portal vein of the rat and to validate this technique as a means of directly measuring portal blood flow in conscious rats. A TTUS flow probe was implanted on the portal veins of 10 rats. One week later, portal flow was measured under basal conditions in these rats by TTUS probes and after pharmacological manipulation of portal flow by intravenous injections of Glypressin or infusions of adenosine while the rats were conscious. Portal flow was simultaneously measured in the same rats using radioactive microspheres. Basal systemic hemodynamics, regional blood flows to splanchnic organs, and portal blood pressure were not significantly modified by the presence of the probe on the portal vein compared with a control group of rats not instrumented with flow probes. Basal portal flows measured by the TTUS and microsphere techniques were not different (20.6 +/- 2.6 and 17.6 +/- 1.3 ml/min). After Glypressin, portal flows measured by the TTUS and microsphere techniques were 12.3 +/- 2.9 and 9.3 +/- 1.9 ml/min and, in response to adenosine, increased to 27.2 +/- 3.4 and 31.3 +/- 4.1 ml/min. There was no significant difference between the TTUS and microsphere flows. Both the relationship between absolute flows and the relationship between changes in flows measured by the two techniques were linear with slopes approaching 1.0. Thus TTUS flow probes can be used to directly measure portal flow from the portal vein in conscious rats. This methodology is as effective as the standard technique of radioactive microspheres. More importantly, the TTUS technique allows for continuous direct measurement of portal flow and eliminates the hazards and sources of error associated with the radioactive microsphere technique.

scholarly journals Portal Vein Dopplerflowmetry in healthy sheep according to age

2017 ◽  
Vol 37 (10) ◽  
pp. 1172-1176 ◽  
Author(s):  
Alexandra F. Belotta ◽  
Bianca P. Santarosa ◽  
Danilo O.L. Ferreira ◽  
Sílvia M.F. Carvalho ◽  
Roberto C. Gonçalves ◽  
...  
Keyword(s):  
Blood Flow ◽  
Portal Vein ◽  
Portal Blood Flow ◽  
Portal Blood ◽  
Mean Values ◽  
Pulsed Doppler Ultrasound ◽  
Healthy Sheep ◽  
Vein Diameter ◽  
Congestion Index ◽  
Post Hoc

ABSTRACT: Pulsed Doppler ultrasound was used to evaluate portal blood flow, portal velocity and portal congestion index in 24 healthy sheep divided into groups (lambs, yearlings and ewes), according to age. Measurements were performed at the 11th right intercostal space using ideal insonation angle and uniform insonation method. Mean values obtained in each group were compared with one-way ANOVA, followed by Tukey post-hoc test. Portal velocity and portal blood flow were statistically similar between the groups (P>0.05). Mean portal velocity were 17.75; 17.13 and 16.75; while mean portal blood flow were 26.65; 31.04 and 24.32 for lambs, yearlings and ewes, respectively. Portal congestion index was statistically distinct between the groups and values for lambs, yearlings and ewes were 0.009; 0.058 and 0.09, respectively (P<0.01). Statistical differences were observed in portal vein diameter, portal vein area and portal congestion index between the groups, presumably due to influence of weight and not to age.

scholarly journals Correction of extrahepatic portal hypertension in pediatric patient after liver transplantation

2017 ◽  
Vol 19 (1) ◽  
pp. 47-51
Author(s):  
A. R. Monakhov ◽  
B. L. Mironkov ◽  
T. A. Dzhanbekov ◽  
K. O. Semash ◽  
Kh. M. Khizroev ◽  
...  
Keyword(s):  
Liver Transplantation ◽  
Blood Flow ◽  
Portal Hypertension ◽  
Portal Vein ◽  
Pediatric Patient ◽  
Portal Blood Flow ◽  
Portal Blood ◽  
Positive Trend ◽  
Portal Vein Stenosis ◽  
Vein Stenosis

Introduction. Liver transplantation is a multi-component and complex type of operative treatment. Patients undergoing such a treatment sometimes are getting various complications. One of these complications is a portal hypertension associated with portal vein stenosis.Materials and methods. In 6 years after the left lateral section transplantation from living donor in a pediatric patient the signs of portal hypertension were observed. Stenosis of the portal vein was revealed. Due to this fact percutaneous transhepatic correction of portal vein stenosis was performed.Results. As a result of the correction of portal blood flow in the patient a positive trend was noted. According to the laboratory and instrumental methods of examination the graft had a normal function, portal blood flow was adequate. In order to control the stent patency Doppler ultrasound and MSCT of the abdominal cavity with intravenous bolus contrasting were performed. Due to these examinations the stent function was good, the rate of blood flow in the portal vein due to Doppler data has reached 80 cm/sec, and a decrease of the spleen size was noted.Conclusion. Diagnosis and timely detection of portal vein stenosis in patients after liver transplantation are very important for the preservation of graft function and for the prevention of portal hypertension. In order to do that, ultrasound Doppler fluorimetry examination needs to be performed to each patient after liver transplantation. In cases of violation of the blood flow in the portal vein CT angiography performance is needed. Percutaneous transhepatic stenting of portal vein is a minimally invasive and highly effective method of correction of portal hypertension. Antiplatelet therapy and platelet aggregation control are the prerequisites for successful stent function.

Transit time ultrasound measurement of portal blood flow in cattle

1996 ◽  
Vol 1996 ◽  
pp. 239-239
Author(s):  
ARG Wylie ◽  
JD McEvoy ◽  
P McGrattan ◽  
DJ Devlin
Keyword(s):  
Blood Flow ◽  
Transit Time ◽  
Portal Blood Flow ◽  
Nutrient Flux ◽  
Portal Blood ◽  
Ultrasound Measurement ◽  
Once Daily ◽  
Dietary Nutrient ◽  
Frequent Feeding ◽  
Quantitative Characterisation

Portal blood flow (PF) is central to the quantitative characterisation of dietary nutrient uptake. Dilution of PAH (p-aminohippurate) is unsuited to rapidly changing flow and visceral studies often use frequent-feeding to encourage “steady-state” digestion and absorption and minimise postprandial PF variation. Such data is of limited value to understanding nutrient flux and visceral responses to conventional feeding (once/twice daily) eg. insulin levels did not differ on similar ME intakes of frequently-fed (12x2h) forage or concentrates (Reynolds and Tyrrell, 1991) whereas in steers fed once daily, insulin was higher (P<0.10) postprandially on a concentrate diet (Thorp et al., 1996). Transit-time ultrasound (TTU) gives real-time, continuous flow but the steer portal vein was regarded as anatomically unsuitable for TTU (Huntington et al., 1990) with PF of less than half those by PAH (20 vs 42ml/min/kg LW). The current study was initiated to monitor temporal PF changes by TTU in steers fed once-daily.

Transit time ultrasound measurement of portal blood flow in cattle

1996 ◽  
Vol 1996 ◽  
pp. 239-239
Author(s):  
ARG Wylie ◽  
JD McEvoy ◽  
P McGrattan ◽  
DJ Devlin
Keyword(s):  
Blood Flow ◽  
Transit Time ◽  
Portal Blood Flow ◽  
Nutrient Flux ◽  
Portal Blood ◽  
Ultrasound Measurement ◽  
Once Daily ◽  
Dietary Nutrient ◽  
Frequent Feeding ◽  
Quantitative Characterisation

Portal blood flow (PF) is central to the quantitative characterisation of dietary nutrient uptake. Dilution of PAH (p-aminohippurate) is unsuited to rapidly changing flow and visceral studies often use frequent-feeding to encourage “steady-state” digestion and absorption and minimise postprandial PF variation. Such data is of limited value to understanding nutrient flux and visceral responses to conventional feeding (once/twice daily) eg. insulin levels did not differ on similar ME intakes of frequently-fed (12x2h) forage or concentrates (Reynolds and Tyrrell, 1991) whereas in steers fed once daily, insulin was higher (P<0.10) postprandially on a concentrate diet (Thorp et al., 1996). Transit-time ultrasound (TTU) gives real-time, continuous flow but the steer portal vein was regarded as anatomically unsuitable for TTU (Huntington et al., 1990) with PF of less than half those by PAH (20 vs 42ml/min/kg LW). The current study was initiated to monitor temporal PF changes by TTU in steers fed once-daily.

The use of 8-phenyltheophylline as a competitive antagonist of adenosine and an inhibitor of the intrinsic regulatory mechanism of the hepatic artery

1985 ◽  
Vol 63 (6) ◽  
pp. 717-722 ◽  
Author(s):  
W. Wayne Lautt ◽  
Dallas J. Legare
Keyword(s):  
Blood Flow ◽  
Hepatic Artery ◽  
Portal Pressure ◽  
Portal Blood Flow ◽  
Portal Blood ◽  
Maximal Response ◽  
Local Concentration ◽  
Portal Flow ◽  
Response Curves ◽  
Adenosine Concentration

Reduction of portal blood flow results in compensatory vasodilation of the hepatic artery, the hepatic arterial buffer response. The hypothesis tested is that the regulation of the buffer response is mediated by adenosine, where the local concentration of adenosine in the region of the hepatic arterial resistance vessels is regulated by washout of adenosine into portal venules that are in intimate contact with hepatic arterioles. In anesthetized cats, portal flow was reduced to zero by complete occlusion of all arterial supply to the guts. The resultant dilation of the hepatic artery compensated for 23.9 ± 4.9% of the decrease in portal flow. Dose–response curves were obtained for the effect of intraportal adenosine infusion on hepatic arterial conductance in doses that did not lead to recirculation and secondary effects on the hepatic artery via altered portal blood flow. The dose to produce one-half maximal response for adenosine is 0.19 mg∙kg−1∙min−1 (intraportal) and the estimated maximal dilation is equivalent to an increase in hepatic arterial conductance to 245% of the basal (100%)) level. The adenosine antagonist, 8-phenyltheophylline, produced dose-related competitive antagonism of the dilator response to infused adenosine (but not to isoproterenol) and a similar, parallel antagonism of the hepatic arterial buffer response. If supramaximal blocking doses were used, the hepatic artery showed massive and prolonged constriction with blood flow decreasing to zero. The data strongly support the hypothesis that intrinsic hepatic arterial buffer response is mediated entirely by local adenosine concentration. This hypothesis is contrary to the popular views that the hepatic artery is controlled either by myogenic responses to change in portal pressure or by metabolic feedback from the parenchymal cells.

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