Measurement Of Portal Flow Research Articles

Liver Transplant With Double Portal Anastomose: A Case Report

Reno-portal reconstruction is a surgical alternative to achieve enough portal flow in liver transplant when there is a complete portal thrombosis, provided there are collaterals or portosystemic shunt, with or without spleno-renal shunt. We present the case of a 58-year-old man with enolic cirrhosis and a history of gastrointestinal hemorrhage due to esophageal varices and portal thrombosis. The clinical case was discussed in the Transplant Committee, and the patient was included in the surgical waiting list with a Model for End-Stage Liver Disease score of 17 and Child-Pugh score of A6. The preoperative computer tomography scan showed significant collateral circulation with esophageal varices, varices dependent on the inferior mesenteric vein (IMV) and hypoplasic portal vein. During the operation, a large shunt from the IMV to the iliac territory and type II portal thrombosis were observed, which was managed with eversion thrombectomy. A temporary portocaval shunt was performed, showing minimal flow in the portal vein, which did not improve after ligation of the systemic shunt. It was decided to perform a reno-portal anastomosis, after which the portal flow measurement was 600 cc per minute; because of this, it was decided to supplement portal flow with an end-to-side portoportal anastomosis, obtaining a flow of 1300 cc per minute with low resistance (R0.5). The postoperative period was favorable, with good evolution of liver analytical parameters, with permeability of the porto-portal venous anastomoses, reno-portal, arterial, and suprahepatic anastomoses in the imaging tests. If the portal flow is insufficient with a hypoplasic portal vein, a double anastomosis, portoportal, and reno-portal would be a technical resource.

Portal Hemodynamics after Living-Donor Liver Transplantation: Management for Optimal Graft and Patient Outcomes—A Narrative Review

Background: When a partial liver graft is transplanted into a recipient with portal hypertension, it is subject to sinusoidal shear stress, which, in good measure, is essential for regeneration. However, portal hyperperfusion which exceeds the capacity of the graft results in the small-for-size syndrome manifested by ascites, cholestasis and coagulopathy. This review discusses intraoperative hemodynamic variables that have been described in the literature, and inflow modulation strategies and their outcomes. Apart from using donor grafts which are of adequate size for the recipient weight, portal hemodynamics are an important consideration to prevent early allograft dysfunction, graft failure and mortality. Summary: Understanding normal portal hemodynamics, how they change with the progression of cirrhosis, portal hypertension and changes after the implantation of a partial liver graft is key to managing patients with living-donor liver transplantation. If the intraoperative measurement of portal flow or pressure suggests graft portal hyperperfusion, inflow modulation strategies can be adopted. Splenic artery ligation, splenectomy and hemiportocaval shunts are well described in the literature. The proper selection of a donor to match the recipient’s anatomic, metabolic and hemodynamic environment and deciding which modulation strategy to use in which patient is an exercise in sound clinical judgement. Key message: The intraoperative assessment of portal hemodynamics in living-donor liver transplant should be standard practice. Inflow modulation in properly selected patients offers a point-of-care solution to alter portal inflow to the graft with a view to improve recipient outcomes. In patients with small (anatomically/metabolically) grafts, using inflow modulation can result in outcomes equivalent to those in patients in whom larger grafts are used.

Spanish Survey on Liver Surgery Units

Purpose: The technical, human, scientific and medical assistance characteristics of the Units that attend a complex pathology are little studied and known. Material and Methods: Multi-institutional descriptive study (survey) on the characteristics of the Units where liver surgery (LS) is performed in Spain. Results: 88 surveys were sent. 60 centres answered (68.2%) belonging to all spanish autonomous communities (17). The sum of inhabitants attended was near 35 millions inhabitants (75% of spanish population). Mean number of beds per hospital was 740. 21 Units (35%) also perform liver transplantation. The mean number of surgeons per Unit is 5. Only 3 Units had a HPB fellowship program. 100% of the Units have intraoperative ultrasound for open approach and 50 (83.3%) have intraoperative ultrasound for laparoscopic approach. In 61.7% of the Units (37/60) the ultrasound was performed by the surgeon, radiologist 15% (9/60) and both 23.3% (14/60). 65% (39/60) of the Units have a 3D laparoscopic tower. 65% (39/60) have an ICG module. 95% (57/60) have the equipment to perform radiofrequency ablation of lesions. 40% has Portal flow measurement device (24/60). 100% can perform intraoperative cholangiography. The mean of liver resections per Unit during 2019 was: 20 major hepatectomies, 29 minor hepatectomies and 3 liver hydatidosis cases. Mean percentage of laparoscopic liver surgery was 20%. Preoperative nutritional assessment is carried out systematically by 43.3% Units (26/60), selectively 50% (30/60) and never 6.7% (4/60). Operative fragility is assessed in 45% of the Units (27/60), selectively in 50% and never in 6.7% (4/60). 86.7% Units (52/60) have a preoperative rehabilitation program, and it is systematically applied by 42.3% (22/52) and selectively by 57.7% (30/52). Answers about real-life practice in liver resections are in Table 1. Laparoscopic approach is more frequent in minor hepatectomies. Abdominal drain and hemostatics are more employed in major resections. In 2015-2018, 39 Units published 226 manuscripts. Mean impact factor/paper was 1,3. Conclusions: This survey provides updated information about the majority of the Units where liver surgery is performed in Spain, and could also serve as a starting point for prospective multicenter studies..EP011_Table IReal life approach comparing minor/major hepatectomiesMINORMAJORpApproach<0.001Laparoscopic50 (83.3%)16 (26.7%)Open10 (16.7%)44 (73.3%)Pringle Manouver0.060Never2 (3.33%)1 (1.67%)Selective41 (68.3%)30 (50.0%)Systematic17 (28.3%)29 (48.3%)Parenchyma Dissection1.000Ultrasonic bisturi55 (91.7%)54 (90.0%)Others5 (8.33%)6 (10.0%)Haemostasia0.798Aquamantis ®7 (11.7%)5 (8.33%)Energy (Caiman ®, Ligasure ®, etc…)4 (6.67%)2 (3.33%)Clips/sutures3 (5.00%)3 (5.00%)Mix of previous methods46 (76.7%)50 (83.3%)Abdominal Drain<0.001031 (51.7%)10 (16.7%)129 (48.3%)48 (80.0%)202 (3.33%)Hemostatics0.001Always15 (25.0%)35 (58.3%)Never3 (5.00%)2 (3.33%)Selective42 (70.0%)23 (38.3%)Eras Protocol0.713No25 (41.7%)28 (46.7%)Yes35 (58.3%)32 (53.3%) Open table in a new tab

Comparison of Two Devices for Intraoperative Portal Venous Flow Measurement in Living-Donor Liver Transplantation: Transit Time Ultrasound and Conventional Doppler Ultrasound

BackgroundIntraoperative portal venous flow measurement provides surgeons with instant guidance for portal flow modulation during living-donor liver transplantation (LDLT). In this study, we compared the agreement of portal flow measurement obtained by 2 devices: transit time ultrasound (TTU) and conventional Doppler ultrasound (CDU). MethodsFifty-four recipients of LDLT underwent intraoperative measurement of portal flow after completion of vascular anastomosis of the implanted partial liver graft. Both TTU and CDU were used concurrently. Agreement of TTU and CDU was assessed by intraclass correlation coefficient using a model of 2-way random effects, absolute agreement, and single measurement. A Bland-Altman plot was applied to assess the variability between the 2 devices. ResultsThe mean, median, and range of portal venous flow was 1456, 1418, and 117 to 2776 mL/min according to TTU; and 1564, 1566, and 119 to 3216 mL/min according to CDU. The intraclass correlation coefficient of portal venous flow between TTU and CDU was 0.68 (95% confidence interval, 0.51–0.80). The Bland-Altman plots revealed an average variation of 4.8% between TTU and CDU but with a rather wide 95% confidence interval of variation ranging from −57.7% to 67.4%. ConclusionsIntraoperative TTU and CDU showed moderate agreement in portal flow measurement. However, a relatively wide range of variation exists between TTU and CDU, indicating that data obtained from the 2 devices may not be interchangeable.

Effect of Food Intake on Intravoxel Incoherent Motion and T2* in the Healthy Liver

Introduction: To evaluate the effect of increasing portal flow due to food intake on the parameters of Intravoxel Incoherent Motion (IVIM) and T2* relaxation time in healthy liver. Materials and methods: The subjects consisted of 15 healthy volunteers. We used a 1.5 T MRI system. All subjects received MRI three times as follows: after overnight fasting but before food intake, at 30 min, and at 4 h after food intake. MRI was repeated at a greater than 1 week interval. All subjects had 800 kcal of Calorie Mate. The echoplanar diffusion-weighted imaging was performed under free breathing and 10 b-values (0, 10, 20, 30, 50, 80, 100, 200, 400, 800 s/mm2) were obtained. T2*-weighted imaging with multi-echo gradient-echo sequence was performed with Siemens MapIt software under breath-holding. The portal flow measurement was performed with phase contrast sequence. The parameters of IVIM including ADC, DC, D*, and PF were calculated and T2* relaxation time was obtained using MapIt. Results: The portal blood flow increased significantly 30 min after food intake (P<0.0001). The ADC, DC, D*, PF and T2* values after overnight fasting, at 30 min, and at 4 h after food intake showed no significant differences after food intake. Conclusion: Increasing portal venous flow after food intake does not affect IVIM parameters and T2* of liver parenchyma in healthy volunteers.

The evolution of anterior sector venous drainage in right lobe living donor liver transplantation: does one technique fit all?

In living donor liver transplantation (LDLT), an adequate hepatic venous outflow constitutes one of the basic principles of a technically successful procedure. The issue of whether the anterior sector (AS) of the right lobe (RL) graft should or should not be routinely drained has been controversial. The aim of this 10-year, single-center, retrospective cohort study was to review the evolution of our hepatic venous outflow reconstruction technique in RL grafts and evaluate the impact of routine AS drainage strategy on the outcome. The study group consisted of 582 primary RL LDLT performed between July 2004 and December 2014. The cases were divided into 3 consecutive periods with different AS venous outflow reconstruction techniques, which included middle hepatic vein (MHV) drainage in Era 1 (n=119), a more selective AS drainage with cryopreserved homologous grafts in Era 2 (n=391), and routine segment 5 and/or 8 oriented AS drainage with synthetic grafts in Era 3 (n=72). Intraoperative portal flow measurement with routine splenic artery ligation (SAL) technique (in RL grafts with a portal flow of ≥ 250 mL/min/100 g liver tissue) was added later in Era 3. These 3 groups were compared in terms of recipient and donor demographics, surgical characteristics and short-term outcome. The rate of AS venous drainage varied from 58.8% in Era 1 and 35.0% in Era 2 to 73.6% in Era 3 (P<0.001). Perioperative mortality rate of recipients significantly decreased over the years (15.1% in Era 1 and 8.7% in Era 2 vs. 2.8% in Era 3, P=0.01). After the addition of SAL technique in the 45 cases, there was only 1 graft loss and no perioperative mortality. One-year recipient survival rate was also significantly higher in Era 3 (79.6% in Era 1 and 86.1% in Era 2 vs. 92.1% in Era 3, P=0.002). Routine AS drainage via segment 5 and/or 8 veins using synthetic grafts is a technique to fit all RL grafts in LDLT. Addition of SAL effectively prevents early graft dysfunction and significantly improves the outcome.

Dynamic measurements of total hepatic blood flow with Phase Contrast MRI

Background/Aims To measure total hepatic blood flow including portal and proper hepatic artery flows as well as the temporal evolution of the vessel's section during a cardiac cycle. Methods Twenty healthy subjects, with a mean age of 26 years, were explored. Magnetic resonance imaging blood flow measurements were carried out in the portal vein and the proper hepatic artery. MR studies were performed using a 1.5T imager (General Electric Medical Systems). Gradient-echo 2D Fast Cine Phase Contrast sequences were used with both cardiac and respiratory gatings. Data analysis was performed using a semi-automatic software built in our laboratory. Results The total hepatic flow rate measured was 1.35 ± 0.18 L/min or 19.7 ± 4.6 mL/(min kg). The proper hepatic artery provided 19.1% of the total hepatic blood flow entering the liver. Those measurements were in agreement with earlier studies using direct measurements. Mean and maximum velocities were also assessed and a discrepancy between our values and the literature's Doppler data was found. Measurements of the portal vein area have shown a mean variation, defined as a “pulsatility” index of 18% over a cardiac cycle. Conclusions We report here proper hepatic artery blood flow rate measurements using MRI . Associated with portal flow measurements, we have shown the feasibility of total hepatic flowmetry using a non-invasive and harmless technique.

Quantitative measurement of portal blood flow by magnetic resonance phase contrast: comparative study of flow phantom and Doppler ultrasound in vivo.

A non-invasive method for measuring portal blood flow by magnetic resonance (MR) phase contrast was evaluated in a flow phantom and 20 healthy volunteers. In a flow phantom study, the flow volumes and mean flow velocities measured by MR phase contrast showed close correlations with those measured by electromagnetic flowmetry. In 20 healthy volunteers, the cross-sectional areas, flow volumes and mean flow velocities measured by MR phase contrast correlated well with those measured by the Doppler ultrasound method. Portal blood flow averaged during the imaging time could be measured under natural breathing conditions by using a large number of acquisitions without the limitations imposed on the Doppler ultrasound method. MR phase contrast is considered to be useful for the non-invasive measurement of portal blood flow.

Hepatic portal venous flow in patients undergoing tricuspid valve surgery.

To determine the changes of flow in the hepatic artery and portal vein of patients undergoing tricuspid valve repair together with mitral valve replacement. Non-randomised parallel group study. Tertiary referral centre. 18 patients with mitral valve disease with or without tricuspid regurgitation (age range 46-73; six men) and six patients with coronary artery disease and normal left ventricular function (women age range 39-78; four men). Mitral valve replacement with or without modified De Vega repair of the tricuspid valve or coronary artery bypass surgery. Flow in the hepatic artery and portal vein as measured by duplex Doppler flowmetry before and two to four weeks after operation. Preoperative hepatic artery flow was less in patients with mitral valve disease than in patients with coronary artery disease (162.7(13.1) ml.min-1 v 242.5(6.6) ml.min-1, p < 0.05). Portal vein perfusion was significantly reduced only in patients with associated tricuspid regurgitation compared with (844(83) ml.min-1 v 1422(64) ml.min-1 p < 0.05). Hepatic perfusion was unaltered after operation in patients undergoing coronary artery bypass surgery (p > 0.05). Flow in the hepatic artery and portal vein was improved only in patients undergoing mitral valve replacement with associated tricuspid valve repair (p < 0.05). Abnormalities of hepatic perfusion can be measured non-invasively in all patients with mitral valve disease but especially in those with associated tricuspid regurgitation needing valve repair. These abnormalities improved two to four weeks after mitral valve surgery and tricuspid valve repair, suggesting that measurement of portal flow might be a useful means of assessing the severity of tricuspid regurgitation.

Duplex Doppler measurements of portal venous flow in normal subjects

We investigated the variability of quantitative duplex Doppler measurements of portal flow. Measurements were validated in vitro using a flow phantom. The measured flow Q (ml/min), is related to the actual phantom output P (ml/min) according to the following formula: Q = 1.08 (P + 44) (r = 0.998). To estimate inter- and intra-observer variance, 38 subjects without portal hypertension were examined in two groups. Two observers examined the first group of subjects (n = 19), from a routine daily ultrasound schedule. Significant differences were found in mean +/- S.D. portal flow (692 +/- 182 ml/min vs. 613 +/- 185 ml/min, p = 0.04) and mean +/- S.D. velocity (15.3 +/- 3.9 cm/s vs. 13.2 +/- 2.6 cm/s, p = 0.01). The combined inter- and intra-observer coefficient of variation (S.D.) was 24% (158 ml/min), 9% (0.92 mm) and 24% (3.4 cm/s) for portal flow, diameter and velocity respectively. Non-systematic components of variance were the largest. Patient characteristics, age, sex, height, weight and body surface area did not influence measurement variations. In the second group of healthy volunteers (n = 19), where variance in measurements over 3 consecutive days was comparable to the combined variance in the first group, the non-systematic variance component was also the largest. We conclude that quantitative duplex Doppler measurements of portal venous flow are mainly subject to non-systematic variability. A coefficient of variation of 24% can be expected in diagnostic measurements in a single patient. Examination by a single observer is advisable. The value of this technique lies in the analysis of pathophysiological mechanisms in portal flow changes in large groups of subjects.

Accuracy and reproducibility of portal flow measurement by Doppler US

Accuracy and reproducibility of portal flow measurement by Doppler US

Observer variability in echo-Doppler measurements of portal flow in cirrhotic patients and normal volunteers

The intraobserver and interobserver variability in measuring the portal vein flow by the echo-Doppler technique was evaluated in a blind controlled study. A total of 22 cirrhotic patients and 14 normal volunteers were examined by two skilled operators using duplex Doppler within a period of 1–3 mo (6 cirrhotics and 7 normal volunteers by both observers). Area, mean velocity, and flow were measured (4 measurements: A, B on day 1; C, D on day 2). The intraclass correlation coefficient was used to assess both the statistical and clinical significance of intraobserver and interobserver agreement for the measurements of these three parameters. The level of intraobserver agreement for each parameter on normal subjects and cirrhotics was obtained from the two measurements on the same day and from the two measurements at the same time on consecutive days. Overall agreement between the four measurements was also calculated. Levels of interobserver agreement were obtained by calculating separately the intraclass correlation coefficient from each of the four pairs of measurements made on the same subject by the two observers over the same period of 2 days. The coefficient of variation was also used to compare the variability in these measurements. Overall, intraobserver agreement on normal subjects varied from good to excellent for observer 1, and from fair to good for observer 2. On cirrhotic patients, observer 1 was excellent at all times for all parameters. Observer 2 had lower intraclass correlation coefficient values, especially for velocity on consecutive days. For the best of the two observers on the portal flow, the coefficient of variation in cirrhotic patients ranged from 2%–30% with a mean ± SEM of 12% ± 4%. No acceptable interobserver agreement was found between the two observers in either of the two samples of subjects. These results support the use of this technique mainly for the determination of rapid and large changes in portal hemodynamics within a short period of time. The technique seems to have low precision in monitoring chronic changes in portal hemodynamics.

Portal blood flow in cirrhosis of the liver.

Direct measurements of portal flow and pressure in a relatively large number of patients with cirrhosis show a marked reduction in flow associated with a nearly constant plateau of portal pressure. This lack of correlation indicates the complex relationships of resistances in the splanchnic, collateral, and hepatic circuits determining the division of the available splanchnic flow between the portal vein and the collateral pathways. Subtracting the measured portal flow from well-established estimates of total hepatic blood flow in cirrhosis suggests that the hepatic artery contributes more than one-half of the blood perfusing the cirrhotic liver. There was no instance of retrograde portal flow during the preshunt measurements, although such reversal was frequent after side-to-side portacaval anastomosis. Attempting to explain the plateau of portal pressure in the face of an increasing outflow resistance presumably associated with progress of the disease, we postulate that an augmented inflow resistance to the splanchnic chamber reduces splanchnic flow in cirrhosis. End-to-side portacaval anastomosis did not return normal portal flow, although it decreased pressure to accepted control levels. The assumption is that most of the splanchnic blood was flowing through the shunt, leading to a high splanchnic resistance in the immediate postshunt status. If this resistance was previously elevated, as suggested by the plateau of portal pressure, the mechanism responsible for the elevation was not immediately deactivated after the shunt, and the true effect of the operation upon splanchnic flow may not be measurable at such time. Respiratory oscillations were a significant component of portal flow in cirrhosis before and after portacaval anastomosis, indicating the limitations of any steady state analysis of the circulatory derangement in cirrhosis.