what is patent hepatic vasculature

Inferior Vena Cava: Anatomy, Function, and Significance - Verywell volume8,pages 127140 (2017)Cite this article. Unless the vessel is patent, additional studies should be performed with a contralateral upper extremity injection to permit adequate contrast opacification. The inlet flow comes from the hepatic artery and the portal vein constituting the triad (the third element being the bile canal). Nevertheless, and following the work of Revellin et al.31, Hess-Murrays law remains valid even with a power-law model. 16b). Bhattacharya S, Shoda LKM, Zhang Q, Woods CG, Howell BA, Siler SQ, Woodhead JL, Yang Y, McMullen P, Watkins PB, Andersen M. E modeling drug- and chemical-induced hepatotoxicity with systems biology approaches. 9). b: CT scout image after extravasation of intravenously administered contrast in the left upper extremity allows assessment of the extent of extravasation and permits evaluation of possible compartment syndrome. 16a). A non-diagnostic CTA following the initial contrast injection can be secondary to many causes; these include both extrinsic factors, such as injection technique/equipment failure (iv cannula, power injector), and intrinsic, patient-related factors. The outlet flow (hepatic vein) is located at the center of each lobule. Non-target vessel opacification may hold key to underlying pathophysiology. We are interested in predicting the geometrical features leading to the smallest overall pressure difference possible. The lobules area porous medium located between the tree canopies. PubMed Central The architecture was based on bifurcation patterns. Ann Emerg Med 58(5):452462, e453, Article Numerical modeling of oxygen availability in the AMC bioartificial liver. Modify the injection protocol and post-threshold delay based on these factors. Differential aortic enhancement can also be seen in patients with coarctation of aorta (Fig. There are two significant imaging consequences of this artifact: missing a true pulmonary embolus due to decreased opacification of the pulmonary artery or misinterpreting the decreased vessel attenuation as an embolus when it is not present. WebLiver Vasculature. Axial CT image in 46-year-old patient with 20-year H/O essential hypertension presenting with chest pain being evaluated for aortic dissection demonstrates differential enhancement of the ascending and descending aorta due to severe stenosis from coarctation. What do you mean by hepatic veins and portal veins are patent? 18). Optimal time for acquisition would be when both lumens are opacified. Alternatively, new access from the contralateral extremity vein can be obtained. The Physics of Life: The Evolution of Everything. The mass flow rate that exits one hexagon is mh, and therefore the total mass flow rate through the square delimited by the dashed lines would be 16mh. Understanding these graphs will help the radiologist plan a repeat contrast injection to overcome the deficiencies of the first injection and thus obtain a diagnostic scan. We wrote in Table Table11 the diameter ratios at each generation level, their average value and standard deviation for the 3 flow configurations, calculated from the data provided in Refs. 17af) of aorta, poor opacification of cardiac chambers, and suboptimal enhancement of the pulmonary vessels. Correspondence to PubMedGoogle Scholar. Attenuation-time graph corresponding to the regions of interest (b) shows prolonged pulmonary circulation time of 16s in this patient due to aortic stenosis (normal pulmonary transit time is approximately 79s). Indications for thoracic CTA include pulmonary embolus, acute aortic syndrome, or coronary artery disease. Delayed phase acquisition is recommended for a more accurate estimation of true extent of false lumen thrombus vs. slow flow. AJR Am J Roentgenol 186(4):11161119, Jana M, Gamanagatti SR, Kumar A (2010) Case series: CT scan in cardiac arrest and imminent cardiogenic shock. Imaging pearl: Check the access vein and access cannula before initiating contrast injection. On an average, the measured splitting number is 2.76 for the hepatic artery, 2.80 for the portal vein, and 3.22 for the hepatic vein, which translated into the integer n = 3. Differential enhancement of false lumen of an aortic dissection can also be due to delayed opacification due to higher inherent luminal pressures. Acad Radiol 12(3):276285, Plumb AA, Murphy G (2011) The use of central venous catheters for intravenous contrast injection for CT examinations. Miguel AF. Understanding the way its blood vasculature works is key. The vascular system and the cost of blood volume. Conceptually, the liver vascularization can be seen as 2 trees matching canopy-to-canopy bathing a porous architecture made of lobules, as presented in Fig. Ischemia results from reduced blood flow, reduced oxygen delivery, increased metabolic activity, or all 3. The microcirculation happens through lobules which hexagonal shape corresponds to minimum flow resistances. Vasculature Hepatic Circulation Note that the number of 6 branches is the limit for which the radial connections exhibited in Fig. Insights Imaging 5(4):493506, Article 4a). Normal gallbladder morphology. The lobule is considered to be the liver functional unit, the elemental system. 4b) [15]. The iliac arteries branch off of the bottom of the aorta, the large artery coming out of the top of the heart. Perfusion characteristics of the human hepatic microcirculation based on three-dimensional reconstructions and computational fluid dynamic analysis. In the paper published by Miguel35 in 2016, the equipartition of thermodynamics imperfections concept translates into an equipartition of flow resistances. ROI over aorta never reaches threshold to trigger the scan. Consequences read more , reduced portal blood flow, ascites Ascites Ascites is free fluid in the peritoneal cavity. (MOV 563 kb), Delayed phase axial CT from a CTPE study obtained in a patient with tricuspid atresia and bidirectional cavopulmonary connection demonstrate complete opacification of both pulmonary arteries and the intracardiac Fontan. Extracorporeal membrane oxygenation or ECMO is increasingly being used in adults for pulmonary or cardiopulmonary support in not just pediatric, but also adult patients with severe respiratory failure or following failure to wean from cardiopulmonary bypass after cardiac surgery [31]. Imaging pearl: In patients with known aortic dissection, test bolus can be more useful in identifying time to peak enhancement in true and false lumens. Insights Imaging 8, 127140 (2017). The hepatic portal vein is a vein that receives all the venous blood from the stomach, small and large intestines, Raising the affected limb above the level of the heart may reduce swelling and facilitate absorption of extravasated fluid. The portal vein and hepatic arteries form the liver's dual blood supply. Approximately 75% of hepatic blood flow is derived from the portal vein, while the remainder is from the hepatic arteries. [4] Unlike most veins, the portal vein does not drain into the heart. provided the experimental data and figures, A.S.C. The objective was to connect one inlet at the center of the disc to a large number of points distributed on the disk perimeter. WebThe hepatic artery (which is oxygen-rich) supplies the rest. This is consistent with the results provided by Siggers et al.40 whose finite elements modeling in 2D indicates a reduction in blood flow rate in a square lattice as opposed to a hexagonal one. Furthermore, due to the absence of pumping action of right ventricle, there is passive laminar flow of Fontan circulation, which causes inhomogeneous enhancement, particularly within the conduit [28]. If the patient is not being monitored, and when such a finding is seen on a nondiagnostic CTA, it is imperative to call the code team and immediately begin cardiopulmonary resuscitation rather than planning for a reinjection. Hessheimer AJ, et al. Calculations of the diameter ratio, length ratio and splitting number of branches, data from Debbaut et al.19,29 and Ma et al.22. Manifestations read more ) or in the intrahepatic terminal hepatic venules and hepatic sinusoids (sinusoidal obstruction syndrome Sinusoidal Obstruction Syndrome Hepatic sinusoidal obstruction syndrome is caused by endothelial injury, leading to nonthrombotic occlusion of the terminal hepatic venules and hepatic sinusoids, rather than of the hepatic read more , previously called veno-occlusive disease) but often occurs in both. Portal, splenic, superior mesenteric Total cavopulmonary connection involves a Glenn shunt connecting SVC to the right PA and Fontan shunt connecting IVC to left PA. CT angiography in these patients to visualize the pulmonary arteries or the conduits themselves is challenging since the SVC flow is directed to the right lung and the IVC flow is directed to the lung (Fig. We consider that Ah=AS, which means that the hexagon is reshaped to become a square, and LS=33/42Lh1.6Lh. In our experience, slowing the flow of the circuit to the minimal flow rate that would prevent thrombus formation for the duration of the scan (1520s) has worked well in cases of suspected pulmonary embolism (Fig. Mixing artifacts can be seen in large aortic aneurysms and should not be confused with a thrombus (Fig. Google Scholar, Litmanovich D, Bankier AA, Cantin L, Raptopoulos V, Boiselle PM (2009) CT and MRI in diseases of the aorta. where K is the intrinsic permeability of the lobule. Diffuse obstruction results in congestion of the sinusoids, hepatomegaly, portal hypertension Portal Hypertension Portal hypertension is elevated pressure in the portal vein. By using this website, you agree to our Careful interpretation of power injector graphs, location of region of interest to trigger the scan, and pattern of contrast flow can help determine the cause. Contrast extravasation rates during CT imaging range between 0.1 and 0.9%, with an average rate of 0.4% [13, 14]. Contrast arrival in the target vessel can be determined by using test bolus or bolus tracker technique [7, 8]. In conclusion, each blood architecture corresponds to a system allowing a point-to-volume (or volume-to-point) fluid distribution for minimum pumping work. Bonfiglio A, Leungchavaphongse K, Repetto R, Siggers JH. A 3D porous media liver lobule model: the importance of vascular septa and anisotropic permeability for homogeneous perfusion. brought the medical vision to the work. The radial distribution of the fluid would generate a flow resistance P/mradial which order of magnitude is R/3gdradial4. No ductal dilation or masses. If we look into Fig. The minimum pressure difference is obtained by minimizing p for the fixed volume V. The corresponding diameter ratio is given by31: As the splitting number is n = 3 on an average, Eq. In our approach, the liver becomes a multi-scale dendritic fluid network constituted of superimposed tree-shaped architectures that provides and drains the blood flow. WebA vascular complication is a primary diagnostic consideration in the liver-transplant patient with fulminant hepatic failure, bile leak, relapsing bacteremia, gastrointestinal or abdominal bleeding, or hemobilia. By using low energy virtual monoenergetic images, the energy levels of which are closer to the K edge of iodine, the contrast signal is amplified which can potentially salvage some suboptimal studies. 4, we see that the square image is made of about 16 hexagonal shapes of side Lh. It assumes that the bolus geometry of this initial injection and the final injection for the diagnostic scan would remain the same (Fig. An electrical analogue of the entire human circulatory system. Each central vein of a hexagon receives mh/6 from the 6 triads distant of Lh from the central vein (the hexagon is made of 6 equilateral triangles of side Lh). The lobules which constitute the designed porous medium have a highly regular design. Considering any of the 3 networks, we note that each consists in a tree-shaped architecture delivering the blood through the connection of one inlet to an infinite number of outlets, the lobules (case of the hepatic artery and the portal vein), or from the lobules to one outlet in the case of the HV hepatic venous system. WebA patent paraumbilical vein (PUV) is a frequent finding in patients with cirrhosis when studied by duplex Doppler ultrasound. Adjacent to the Falciform Ligament on Contrast Inclusion in an NLM database does not imply endorsement of, or agreement with, Specific vascular lesions may occur in the hepatic artery, hepatic vein, or portal vein. Learn. Note the complete nonopacification of false lumen. There may be retrograde opacification of IVC, hepatic veins, and even portal vein with dependent pooling of the contrast forming a blood-contrast level (Movie 1) [24]. What does it mean to say portal and hepatic veins are No pleural or pericardial effusion. The physical components of a CTA include the CT scanner, intravenous cannula, access vein size, and power injector; the functional component is the patients cardiac status. Understanding and controlling the liver portal pressure after surgery would be of the utmost importance to guarantee correct regeneration signals and prevent cell death18. The liver vasculature makes its unique among the other organs as it is made of the superimposition of three main networks, two inlets and one outlet. Clin Radiol 69(12):12641272, Article Liver: Blood supply, innervation and anatomy | Kenhub Non-diagnostic thoracic CTAs are frequently encountered in clinical practice. Patient with cardiac arrest at the time of CTA for acute aortic syndrome. In this work we show that the challenge of predicting the hepatic multi-scale vascular network can be met thanks to the constructal law of design evolution. Teutsch HF. Scanning Electron Microscope images of human liver reveal that the elemental system, the lobule, is entirely vascularized19. Diffuse ischemia can cause ischemic hepatitis Ischemic Hepatitis Ischemic hepatitis is diffuse liver damage due to an inadequate blood or oxygen supply. The resistance factor fn is obtained from the search of minimum overall flow resistance in a laminar dendritic structure: the diameter ratio (which follows the Hess-Murays law27,28), the branches lengths and bifurcation angles correspond to minimum pressure losses. 7a and b). The distribution of contrast medium is now being determined by the push from the power injector and the viscosity of the contrast medium. The contrast opacification of the false lumen does not reach the thresholdrequired to trigger the scan as seen on on bolus tracker HU-time graph. Symptoms usually result from abdominal distention. For example, for a pulmonary embolus study, we use a post-threshold delay of at least 5s on a 64 slice scanner, buta longer delay of 8sis used on a 256 or a dual source scanner. The sinusoids are Thoracic venous outlet obstruction of the left subclavian vein with the left arm raised for CTPA, which subsequently resolves upon positioning the arm down at the side. Consequences read more . Curr Probl Diagn Radiol 41(2):5255, Peet RM, Henriksen JD, Anderson TP, Martin GM (1956) Thoracic-outlet syndrome: evaluation of a therapeutic exercise program. Garcea G, Maddern GJ. The portal vein (which is rich in nutrients and relatively high in oxygen) provides two thirds of blood flow to the liver. Liver failure after major hepatic resection. J Thorac Imaging 19(1):17, Wittram C, Yoo AJ (2007) Transient interruption of contrast on CT pulmonary angiography: proof of mechanism. The flow resistance created in the case of a dendritic design is given by. The mesenteric arteries may have variant anatomy in approximately 20% of the population, which may lead to misinterpretation of Doppler examination findings. Nevertheless considering that the hexagonal shape is close to the circle shape, the same expression was used in this work to predict the order of magnitude of the lobule permeability. Graphs and tables from the power injector: pressure-time and flow rate-time graphs. We note that each source is in charge of 1/6th of the hexagonal lobule cross section. The entire network is similar to a river delta, except that in the case of the lobule the fluid flows in the reverse direction as in the river basin. According to the literature15,44,45, the average human liver has a volume of 1500 cm3, and contains 1020% of blood, while it possesses about 106 lobules. Virtual tissues in toxicology. Check for errors and try again. Below are links to the electronic supplementary material. Sequential axial CT images (af) from a test bolus obtained at the level of main pulmonary artery. This way, what was initially a local fluid source becomes a distributed fluid source. Central veins of the thorax convey blood/contrast bolus to the right atrium. ACR Manual on Contrast Media discusses the treatment of contrast extravasation [9]. Lee J, Kim S, Lorente S, Bejan A. Vascularization with trees matched canopy to canopy: Diagonal channels with multiple sizes. Patent mesenteric vasculature and an antimesenteric pattern of involvement, along with reports of hypercoagulability in patients with COVID-19, suggest the necrosis occurred as a result of microvascular thrombosis and associated inflammation. We demonstrated previously that beyond the value of 6 connected branches, radial networks should be replaced by tree-shaped ones with optimized diameter ratios (Eq. Chronic pancreatitis is characterized by histologic read more , tumor), or congenital atresia of the portal vein, Intrahepaticeg, microvascular portal vein obstruction as occurs in schistosomiasis Schistosomiasis Schistosomiasis is infection with blood flukes of the genus Schistosoma, which are acquired transcutaneously by swimming or wading in contaminated freshwater. The initial CECT (a) shows poor opacification of the pulmonary artery despite high density contrast material within the aorta and SVC because deep inspiration resulted in increased venous return from the IVC and dilution of the contrast bolus in the right heart (b) at the time of scanning. Cirrhosis is characterized by regenerative nodules surrounded by dense read more is the most common cause of diffuse intrahepatic venous outflow obstruction. Acute pancreatitis is inflammation that resolves both clinically and histologically. Two images from a CTPE study obtained in a patient with tricuspid atresia and bidirectional cavopulmonary connection demonstrate poor opacification of right pulmonary artery and non-enhancement of left pulmonary artery (a). Each tree architecture is composed of a main trunk subdivided into smaller and smaller braches. Models range from the entire circulatory architecture6 to the hepatic micro circulation7,8. Demondion X, Herbinet P, Van Sint Jan S, Boutry N, Chantelot C, Cotten A (2006) Imaging assessment of thoracic outlet syndrome. Mathematical modeling of the circulation in the liver lobule. Before discharge, a radiologist discusses the findings that would suggest a developing compartment syndrome with the patient. Wechsatol et al.26 showed that they happen because they are the most efficient way, i.e. This result is in agreement with the literature as the radial and tangential permeability of a lobule were estimated to be about 1.5 1014 m2 in Ref46, while Ref11. liver In. To confront the theoretical approach developed in this paper to experimental data, we rely on anatomic results provided by two different groups19,22,29. The modeling of the hepatic circulation has been a challenge for several decades. Once mixed the blood is pushed into the hepatic vein. the contents by NLM or the National Institutes of Health. The CT technician subsequently called the radiologist to check the images and ask for a repeat injection after identifying abnormal contrast enhancement. 5 is a good pattern. 3b) with abrupt cessation of flow, or contrast medium extravasation. Insights Imaging 5(6):731742, Liu KL, Wang YF, Chang YC, Huang SC, Chen SJ, Tsang YM et al (2014) Multislice CT scans in patients on extracorporeal membrane oxygenation: emphasis on hemodynamic changes and imaging pitfalls. J Thorac Imaging 22(2):125129, Ajlan AM, Binzaqr S, Jadkarim DA, Jamjoom LG, Leipsic J (2016) High-pitch Helical dual-source computed Tomographic pulmonary angiography: comparing image quality in inspiratory breath-hold and during free breathing. (See also Overview of Vascular Disorders of the read more . These parameters can be altered to reduce contrast volume in patients with diminished renal function or when a repeat injection becomes necessary in event of an initial, non-diagnostic scan. 2). Portal vein. PubMed Asystole with no cardiac output. The work unveils the structure of the liver blood flow architecture as a combination of superimposed tree-shaped networks and porous system.
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