Inferior Vena Cava Pressure Research Articles

Inferior vena cava collapsibility index for predicting hypotension after spinal anesthesia in patients undergoing total knee arthroplasty.

This study aimed to identify risk factors associated with hypotension in patients undergoing total knee arthroplasty (TKA) under spinal anesthesia. Atotal of 200 patients (50-75years of age) who underwent elective TKA under spinal anesthesia between October 2023 and January 2024 were enrolled. Patients were divided into two groups (hypotensive and nonhypotensive) depending on the occurrence of postspinal anesthesia hypotension (PSAH). Patient characteristics (age, sex, body mass index, and medical history), blood pressure, heart rate, and ultrasound data before anesthesia were documented. Multivariate logistic regression models were used to determine risk factors for hypotension after spinal anesthesia. Furthermore, anomogram was constructed according to independent predictive factors. The area under the curve (AUC) and calibration curves were employed to assess the performance of the nomogram. In total, 175 patients were analyzed and 79(45.1%) developed PSAH. Logistic regression analysis revealed that variability of the inferior vena cava (odds ratio, OR, 1.147; 95% confidence interval, CI: 1.090-1.207; p < 0.001) and systolic arterial blood pressure (SABP, OR 1.078; 95% CI: 1.043-1.115; p < 0.001) were independent risk factors for PSAH. Receiver operating characteristic (ROC) curve analysis showed that the AUC of the inferior vena cava collapsibility index (IVCCI) and SABP alone were 0.806 and 0.701, respectively, while the AUC of both combined was 0.841. Specifically, an IVCCI of > 37.5% and systolic arterial blood pressure of > 157 mm Hg were considered threshold values. Furthermore, we found that the combination had abetter predictive value with higher AUC value, sensitivity, and specificity than the index alone. The nomogram model and calibration curves demonstrated the satisfactory predictive performance of the model. Elevated preoperative systolic arterial blood pressure and ahigher IVCCI were identified as independent risk factors for hypotension in patients receiving spinal anesthesia, which may help guide personalized treatment.

In vitro hemodynamic performance of a blood pump for self-powered venous assist in univentricular hearts

Univentricular heart anomalies represent a group of severe congenital heart defects necessitating early surgical intervention in infancy. The Fontan procedure, the final stage of single-ventricle palliation, establishes a serial connection between systemic and pulmonary circulation by channeling venous return to the lungs. The absence of the subpulmonary ventricle in this peculiar circulation progressively eventuates in failure, primarily due to chronic elevation in inferior vena cava (IVC) pressure. This study experimentally validates the effectiveness of an intracorporeally-powered venous ejector pump (VEP) in reducing IVC pressure in Fontan patients. The VEP exploits a fraction of aortic flow to create a jet-venturi effect for the IVC, negating the external power requirement and driveline infections. An invitro Fontan mock-up circulation loop is developed and the impact of VEP design parameters and physiological conditions is assessed using both idealized and patient-specific total cavopulmonary connection (TCPC) phantoms. The VEP performance in reducing IVC pressure exhibited an inverse relationship with the cardiac output and extra-cardiac conduit (ECC) size and a proportional relationship with the transpulmonary pressure gradient (TPG) and mean arterial pressure (MAP). The ideal VEP with fail-safe features provided an IVC pressure drop of 1.82 ± 0.49, 2.45 ± 0.54, and 3.12 ± 0.43 mm Hg for TPG values of 6, 8, and 10 mm Hg, respectively, averaged over all ECC sizes and cardiac outputs. Furthermore, the arterial oxygen saturation was consistently maintained above 85% during full-assist mode. These results emphasize the potential utility of the VEP to mitigate elevated venous pressure in Fontan patients.

The effect of the conduit size on middle-term outcomes in patients with extracardiac total cavopulmonary connection.

The 18- and 16-mm conduits in extracardiac total cavopulmonary connection (eTCPC) were reported to be optimal based on energy loss and flow stagnation at the relatively early phase. However, because the artificial conduit lacks growth potential, we have recently encountered some cases in which the conduit needs to be changed several years after eTCPC. These cases prompted us to reconsider the surgical strategy for eTCPC. We reviewed our 20-year single-centre experience with eTCPC patients (n = 256) to compare the 18-mm conduit (n = 195) and 16-mm conduit (n = 61) in terms of mortality and morbidity. The 16-mm conduit was used significantly more frequently in patients whose main chamber was right ventricle (P < 0.001). There was also a significant difference in preoperative inferior vena cava pressure (P = 0.008). There was a significant difference in the actuarial rate of freedom from late-occurring complications, including mortality, between the 2 groups (P = 0.003). There was a significant difference in the actuarial rate of reoperation-free survival (P = 0.042); however, there was no significant difference in resurgical intervention for the conduit (P = 0.333). In multivariate analysis, preoperative inferior vena cava pressure was an independent predictor for late-occurring complications (hazard ratio 1.19; P = 0.026). Conduit size (18 or 16 mm) itself was not an independent predictive factor for late-occurring complications (P = 0.690). The mid-term clinical outcomes in patients who underwent eTCPC were excellent with low mortality. Preoperative inferior vena cava pressure was the only predictive risk factor for postoperative morbidity, and the 16 mm conduit was not predictive thereof.

Impact of catheter tip to hepatic vein ostium distance on the validity and prognostication of hepatic venous pressure gradient in cirrhosis

Hepatic venous pressure gradient (HVPG) is an accurate measure of portal hypertension in cirrhosis. However, the effect of catheter tip distance from hepatic vein ostium (HVO) on HVPG is unknown. We performed a retrospective study on 228 patients with 307 HVPGs in our institution. The objectives of this study were to assess the effect of catheter position on the validity of HVPG and its prognostication in cirrhosis. In this study, free hepatic vein pressure (FHVP) was considered optimal when difference between FHVP and inferior vena cava pressure was ≤ 2 mmHg. HVPG progressively decreased (p < 0.001) when measured at increasing distance from HVO due to an increasing FHVP (p = 0.036) but an unchanged wedged hepatic vein pressure (p = 0.343). Catheter tip distance > 5 to ≤ 8 cm [odds ratio {OR} 0.16 (95% CI 0.05–0.47), p = 0.001] and > 8 cm [OR 0.14 (95% CI 0.04–0.47), p = 0.002] compared to ≤ 3 cm from HVO were independent predictors of not achieving optimal FHVP. Baseline HVPG ≥ 16 mmHg was strongly associated with deaths due to cirrhosis and liver transplantation for end-stage liver disease compared to HVPG < 16 mmHg when FHVP was optimal (p < 0.001) but not when it was suboptimal (p = 0.359). Our study showed that FHVP is spuriously elevated when measured at > 5 cm from HVO, resulting in inaccurately low HVPG.

Bio-Humoral and Non-Invasive Haemodynamic Correlates of Renal Venous Flow Patterns across the Heart Failure Spectrum.

Background: We evaluated the bio-humoral and non-invasive haemodynamic correlates of renal congestion evaluated by Doppler renal venous flow (RVF) across the heart failure (HF) spectrum, from asymptomatic subjects with cardiovascular risk factors (Stage A) and structural heart disease (Stage B) to patients with clinically overt HF (Stage C). Methods: Ultrasound evaluation, including echocardiography, lung ultrasound and RVF, along with blood and urine sampling, was performed in 304 patients. Results: Continuous RVF was observed in 230 patients (76%), while discontinuous RVF (dRVF) was observed in 74 (24%): 39 patients had pulsatile RVF, 18 had biphasic RVF and 17 had monophasic RVF. Stage C HF was significantly more common among patients with dRVF. Monophasic RVF was associated with worse renal function and a higher urinary albumin-to-creatinine ratio (uACR). After adjusting for hypertension, diabetes mellitus, the presence of Stage C HF and serum creatinine levels, worsening RVF patterns were associated with higher NT-proBNP levels, worse right ventricular-arterial coupling, larger inferior vena cava and higher echo-derived pulmonary artery wedge pressure. This trend was confirmed when only patients with HF Stage C were analysed after adjusting for the left ventricle ejection fraction (LVEF). Conclusion: Abnormal RVF is common across the HF spectrum. Worsening RVF patterns are independently associated with increased congestion, worse non-invasive haemodynamics and impaired RV-arterial coupling. RVF evaluation could refine prognostic stratification across the HF spectrum, irrespective of LVEF.

Endovascular approach for nutcracker syndrome using an arterial stent: The first Latin-American experience

ObjectiveThe exact prevalence of nutcracker syndrome (NCS) is unknown, due to the very low incidence of this disease plus the absence of definitive diagnostic criteria. Some authors have reported a higher prevalence of this condition in women, however published and available information is limited. Due to symptoms and consequences that can cause, it is important to suspect it and diagnose it. The aim of this study was to report the outcomes of the first Latin-American experience in the treatment of NCS using an endovascular approach with a left renal vein (LRV) balloon and arterial stent angioplasty. MethodsThe study design was a retrospective cohort analysis of 11 patients who underwent endovascular approach with LRV balloon and arterial stent angioplasty for the treatment of NCS between January 2019 and April 2022 in Bogota, Colombia. ResultsDuring January 2019 to April 2022, 553 patients were treated for congestive pelvic syndrome. Only 11 patients have clinical criteria (hematuria, varicose pelvic veins, and left flank pain), imaging diagnostic criteria (abdominal veins Doppler ultrasound or abdominal computed tomography with superior mesentery artery – abdominal aorta angle <39°) and an average of LRV – inferior vena cava pressure measurement comparison difference of 6mmHg for NCS. The 100% were female patients. All the patients were under 65 years and underwent endovascular approach (EVA) with LRV balloon and arterial stent angioplasty. The 100% of patients presented resolution of the collateral vein circulation in the final control phlebo-cavography. The average age was 46.5 years old. Ten patients had an anterior type of NCS and only 1 had a posterior type of NCS. None of the patients had NCS due to secondary causes such as pancreatic head tumors. ConclusionsThis study shows that the endovascular approach with LRV balloon and arterial stent angioplasty is a safe and cost-effective treatment for NCS with low incidence of complications and no need of postoperative reintervention in short and middle term follow-up.

Ascites in Animals With Right Heart Failure: Correlation With Lymphatic Dysfunction.

Background Congestive heart failure is a leading cause of morbidity and mortality worldwide. One of the signs of congestive heart failure is fluid overload including pulmonary edema, peripheral edema, and ascites. The cause of fluid overload remains incompletely understood, and management of these patients continues to be a challenge. The role of lymphatic circulation abnormalities in the cause and pathophysiology of fluid overload also remains unclear. Here we report on a study in a large animal model of right heart failure caused by severe tricuspid regurgitation comparing cardiovascular and lymphatic findings in a group of animals that did not develop ascites with a group of animals that developed ascites. Methods and Results Thirteen Yorkshire pigs were included in this study divided into 2 groups. Group 1 included 6 animals that did not develop ascites, and Group 2 included 7 animals that had developed ascites. The groups were compared on hemodynamic parameters as well as comparison of the animal's lymphatic anatomy and function. There was no difference between the groups in degree of tricuspid regurgitation and central venous pressure, with inferior vena cava pressure measuring 11.6±1.6 versus 13.2±3.7 (P=0.534) and superior vena cava pressure measuring 12.0±2.3 versus 13.7±3.2 (P=0.366). There was also no difference between the groups in all measured hemodynamic parameters, including right ventricular pressure, pulmonary artery pressure, and left ventricular function. The weighted liver size in the ascites group was significantly larger than in the nonascites group (30.3±12.4 versus 63.3±14.0 mL/kg, respectively; P=0.001). The 2 groups also differed in the number of animals with regurgitant thoracic duct flow (Group 1: 1/6,17% versus Group 2: 6/7, 86%; P=0.029) and the minimal thoracic duct diameter (Group 1: 2.3±0.3 versus Group 2: 4.2±2.2; P=0.035). Conclusions In animals with right heart failure caused by severe tricuspid regurgitation, fluid overload did not correlate with hemodynamic parameters but rather with changes in the lymphatic system, including regurgitant lymphatic flow, minimal thoracic duct diameter, and liver size. This study is consistent with lymphatic dysfunction and not cardiovascular function playing a significant role in the cause of fluid overload. Further studies are needed to confirm these findings.

Comparing the predictive ability of portoatrial and portocaval gradient after transjugular intrahepatic portosystemic shunt creation for variceal rebleeding.

Measuring the portal pressure gradient from the portal vein (PV) to the inferior vena cava (IVC) or to the right atrium (RA) remains controversial. The aim of our study was to compare the predictive ability of portoatrial gradient (PAG) and portocaval gradient (PCG) for variceal rebleeding. The data of 285 cirrhotic patients with variceal bleeding undergoing elective transjugular intrahepatic portosystemic shunt (TIPS) in our hospital were analyzed retrospectively. The variceal rebleeding rates were compared between groups categorized by established or modified thresholds. The median follow-up time was 30.0months. After TIPS, PAG was equal to (n = 115) or more than (n = 170) PCG. The pressure of IVC was defined as an independent predictor for a PAG-PCG difference of ≥ 2mmHg (p < 0.001, OR 1.23, 95% CI 1.10-1.37). Using a threshold of 12mmHg, PAG (p = 0.081, HR 0.63, 95% CI 0.37-1.06) could not predict variceal rebleeding but PCG could (p = 0.003, HR 0.45, 95% CI 0.26-0.77). This pattern was unchanged when a ≥ 50% reduction from baseline was also considered as a threshold (PAG/PCG: p = 0.114 and 0.001). Subgroup analyses showed that only in patients with post-TIPS IVC pressure < 9mmHg (p = 0.018), PAG could predict variceal rebleeding. Because PAG was on average 1.4mmHg higher than PCG, patients were classified by a PAG of 14mmHg, and there was no difference in rebleeding rates between these two groups (p = 0.574). For patients with variceal bleeding, the predictive ability of PAG is limited. The portal pressure gradient should be measured between the PV and IVC.

Early Experience With Reverse Double Switch Operation for the Borderline Left Heart

This study reviews our early experience with the "reverse" double switch operation (R-DSO) for borderline left hearts. A retrospective review of children with borderline left hearts who underwent R-DSO between 2017 and 2021 was conducted. Patient characteristics and early hemodynamic and clinical outcomes were collected. R-DSO was performed in 8 patients with no operative or postoperative deaths; 5 underwent decompressing bidirectional Glenn. Left ventricular (LV) poor-compliance was the dominant pathophysiology. Four patients had undergone staged LV recruitment but were not candidates for anatomical biventricular circulation due to LV hypoplasia and/or diastolic dysfunction. 7/8 patients had risk factors for Fontan circulation including pulmonary vein stenosis, pulmonary hypertension, and pulmonary artery stenosis. Median age at R-DSO was 3.7 years (19 months-12 years). All patients were in sinus rhythm at discharge. At median follow-up of 15 months (57 days-4.1 years) no mortalities, reoperations or heart transplants had occurred. All patients had normal morphologic LV systolic function. In one patient, pre-existing pulmonary hypertension (HTN) resolved after R-DSO. Reinterventions included transcatheter mitral valve replacement for residual mitral stenosis and neo-pulmonary balloon valvuloplasty. In 4 patients follow-up catheterization done at a median of 519 days (320 days-4 years) demonstrated median cardiac index of 3.2 L/min/m2 (2.2-4); median sub-pulmonary left ventricular end diastolic pressure was 9 mm Hg (7-15); median inferior vena cava/baffle pressure was 8 mm Hg (7-13). R-DSO is an alternative to anatomical biventricular repair or single ventricle palliation in patients with borderline left hearts and can result in low inferior vena cava pressures and favorable early results. This approach can also relieve pulmonary HTN and allow future transplant candidacy.

Inhibition of platelet-derived growth factor pathway suppresses tubulointerstitial injury in renal congestion.

Objective:Increased central venous pressure in congestive heart failure is responsible for renal dysfunction, which is mediated by renal venous congestion. Pericyte detachment from capillaries after renal congestion might trigger renal fibrogenesis via pericyte-myofibroblast transition (PMT). Platelet-derived growth factor receptors (PDGFRs), which are PMT indicators, were upregulated in our recently established renal congestion model. This study was designed to determine whether inhibition of the PDGFR pathway could suppress tubulointerstitial injury after renal congestion.Methods:The inferior vena cava between the renal veins was ligated in male Sprague-Dawley rats, inducing congestion only in the left kidney. Imatinib mesylate or vehicle were injected intraperitoneally daily from 1 day before the operation. Three days after the surgery, the effect of imatinib was assessed by physiological, morphological and molecular methods. The inhibition of PDGFRs against transforming growth factor-β1 (TGFB1)-induced fibrosis was also tested in human pericyte cell culture.Results:Increased kidney weight and renal fibrosis were observed in the congested kidneys. Upstream inferior vena cava (IVC) pressure immediately increased to around 20 mmHg after IVC ligation in both the imatinib and saline groups. Although vasa recta dilatation and pericyte detachment under renal congestion were maintained, imatinib ameliorated the increased kidney weight and suppressed renal fibrosis around the vasa recta. TGFB1-induced elevation of fibrosis markers in human pericytes was suppressed by PDGFR inhibitors at the transcriptional level.Conclusion:The activation of the PDGFR pathway after renal congestion was responsible for renal congestion-induced fibrosis. This mechanism could be a candidate therapeutic target for renoprotection against renal congestion-induced tubulointerstitial injury.

Study on the correlation between PPG and HVPG in patients with portal hypertension

Objective: To explore the correlation between portal vein pressure gradient (PPG) and hepatic vein pressure gradient (HVPG) in patients with portal hypertension (PHT). Methods: 752 cases with portal hypertension (PHT) who underwent transjugular intrahepatic portosystemic shunt (TIPS) and met the enrollment criteria between January 2016 to December 2019 were analyzed for hepatic vein, inferior vena cava and portal vein pressure. Paired t-test was used for analysis. Pearson correlation test was used to estimate correlation coefficient and coefficient of determination. P<0.05 were considered statistically significant. Results: Wedged hepatic vein pressure (WHVP), portal vein pressure (PVP), correlation coefficient, and coefficient of determination were 27.98±8.95 mmHg, 33.85±7.33 mmHg, 0.329 (P<0.001), and 0.108, respectively. HVPG, PPG,correlation coefficient, and coefficient of determination were 16.84±7.97 mmHg, 25.11±6.95 mmHg (P<0.001), 0.145, and 0.021 (P<0.001), respectively. The difference between HVPG and PPG was greater than 5 mmHg in 524 cases, accounting for 69.7%. The difference between HVPG and PPG was within 5 mmHg or basically equal in 228 cases, accounting for 30.3%. The correlation coefficient between free hepatic venous pressure (FHVP) and inferior vena cava pressure (IVCP) was 0.568 (P<0.001), and the coefficient of determination was 0.323. According to the presence or absence of hepatic venous collaterals after balloon occluded hepatic angiography, they were divided into two groups: 157 (20.9%) cases in the group with hepatic venous collaterals, and 595 (79.1%) cases in the group without hepatic venous collaterals. The parameters of the two groups were compared: WHVP (15.73±3.63) mmHg vs. (31.22±6.90) mmHg, P<0.001; PVP (31.69±8.70) mmHg vs. (34.42±6.81) mmHg, P<0.001; HVPG (7.18±4.40) mmHg vs. (19.40±6.62) mmHg, P<0.001; PPG (24.24±8.11) mmHg vs. (25.34±6.60) mmHg, P<0.001; free hepatic venous pressure (FHVP) (8.58±3.37) mmHg vs. (11.82±5.07) mmHg , P<0.001; inferior vena cava pressure (IVCP) (7.45±3.29) mmHg vs. (9.09±4.14) mmHg, P<0.001. Conclusion: The overall correlation is poor between HVPG and PPG. HVPG of most patients is not an accurate representation of PPG, and the former is lower than the latter. Hepatic venous collateral formation is one of the important reasons for the serious underestimation of HVPG values.

Correlation of pressure gradient in three hepatic veins with portal pressure gradient.

BACKGROUNDThe liver is one of the most important organs in the human body, with functions such as detoxification, digestion, and blood coagulation. In terms of vascular anatomy, the liver is divided into the left and the right liver by the main portal vein, and there are three hepatic efferent veins (right, middle, and left) and two portal branches. Patients with impaired liver function have increased intrahepatic vascular resistance and splanchnic vasodilation, which may lead to an increase in the portal pressure gradient (PPG) and cause portal hypertension (PHT). In order to measure the increased pressure gradient of portal vein, the hepatic venous pressure gradient (HVPG) can be measured to reflect it in clinical practice. The accuracy of PPG measurements is directly related to patient prognosis.AIMTo analyze the correlation between HVPG of three hepatic veins and PPG in patients with PHT.METHODSFrom January 2017 to December 2019, 102 patients with PHT who met the inclusion criteria were evaluated during the transjugular intrahepatic portosystemic shunt procedure and analyzed.RESULTSThe mean HVPG of the middle hepatic vein was 17.47 ± 10.25 mmHg, and the mean HVPG of the right and left hepatic veins was 16.34 ± 7.60 and 16.52 ± 8.15 mmHg, respectively. The average PPG was 26.03 ± 9.24 mmHg. The correlation coefficient and coefficient of determination of the right hepatic vein, middle hepatic vein, and left hepatic vein were 0.15 and 0.02 (P = 0.164); 0.25 and 0.05 (P = 0.013); and 0.14 and 0.02 (P = 0.013), respectively. The mean wedged hepatic vein/venous pressure (WHVP) of the middle and left hepatic veins was similar at 29.71 ± 12.48 and 29.1 ± 10.91 mmHg, respectively, and the mean WHVP of the right hepatic vein was slightly lower at 28.01 ± 8.95 mmHg. The mean portal vein pressure was 34.11 ± 8.56 mmHg. The correlation coefficient and coefficient of determination of the right hepatic vein, middle hepatic vein, and left hepatic vein were 0.26 and 0.07 (P = 0.009); 0.38 and 0.15 (P < 0.001); and 0.26 and 0.07 (P = 0.008), respectively. The average free hepatic venous pressure (FHVP) of the right hepatic vein was lowest at 11.67 ± 5.34 mmHg, and the average FHVP of the middle and left hepatic veins was slightly higher at 12.19 ± 4.88 and 11.67 ± 5.34 mmHg, respectively. The average inferior vena cava pressure was 8.27 ± 4.04 mmHg. The correlation coefficient and coefficient of determination of the right hepatic vein, middle hepatic vein, and left hepatic vein were 0.30 and 0.09 (P = 0.002); 0.18 and 0.03 (P = 0.078); and 0.16 and 0.03 (P = 0.111), respectively.CONCLUSIONMeasurement of the middle hepatic vein HVPG could better represent PPG. Considering the high success rate of clinical measurement of the right hepatic vein, it can be the second choice.

Use of an intraoperative veno-venous bypass during liver transplantation: an observational, single center, cohort study.

As previous studies demonstrated conflicting results, we investigated the hemodynamic and renal outcomes of the intra-operative use of a veno-venous bypass during liver transplantation. The intraoperative levels of mean artery pressure, cardiac index, inferior vena cava and renal perfusion pressures were compared in liver transplant patients receiving or not the bypass. We enrolled 38 patients: 20 with the bypass and 18 without. No differences characterized the two groups regarding gender (P=0.95), age (P=0.32), BMI (P=0.09), liver disease indicating LT and preoperative serum creatinine levels. Patients with the bypass received more intraoperative fluids (crystalloids and colloids) but with no difference in terms of intraoperative blood products and vasopressors requirements (P=0.33). After clamping of the inferior vena cava, patients with the bypass showed higher mean artery pressure. Simultaneously, pressure in the inferior vena cava below the clamp level sharply increased vs. baseline (P<0.0001) independently of the use of the bypass and remained high until clamp release. Consequently, renal perfusion pressure dropped abruptly (P<0.0001) after vena cava clamping and returned to baseline only upon clamp removal. Overall, 18 subjects developed postoperative acute kidney injury which was equally distributed between patients with (n=9) or without (N.=8) the bypass. Our data suggest that the use of a veno-venous bypass fails to release the increased renal venous backflow from inferior vena cava clamping resulting in renal congestion with reduced renal perfusion pressure.

Fontan-associated liver disease.

Fontan-associated liver disease.

Parametric investigation of an injection-jet self-powered Fontan circulation

Approximately 1/2500 babies are born with only one functioning ventricle and the Fontan is the third and, ideally final staged palliative operation for these patients. This altered circulation is prone to failure with survival rates below 50% into adulthood. Chronically elevated inferior vena cava (IVC) pressure is implicated as one cause of the mortality and morbidity in this population. An injection jet shunt (IJS) drawing blood-flow directly from the aortic arch to significantly lower IVC pressure is proposed. A computer-generated 3D model of a 2–4 year old patient with a fenestrated Fontan and a cardiac output of 2.3 L/min was generated. The detailed 3D pulsatile hemodynamics are resolved in a zero-dimensional lumped parameter network tightly-coupled to a 3D computational fluid dynamics model accounting for non-Newtonian blood rheology and resolving turbulence using large eddy simulation. IVC pressure and systemic oxygen saturation were tracked for various IJS-assisted Fontan configurations, altering design parameters such as shunt and fenestration diameters and locations. A baseline “failing” Fontan with a 4 mm fenestration was tuned to have an elevated IVC pressure (+ 17.8 mmHg). Enlargement of the fenestration to 8 mm resulted in a 3 mmHg IVC pressure drop but an unacceptable reduction in systemic oxygen saturation below 80%. Addition of an IJS with a 2 mm nozzle and minor volume load to the ventricle improved the IVC pressure drop to 3.2 mmHg while increasing systemic oxygen saturation above 80%. The salutary effects of the IJS to effectively lower IVC pressure while retaining acceptable levels of oxygen saturation are successfully demonstrated.

Abstract 14301: Investigation of an Injection-Jet Self-Powered Fontan Circulation

Introduction: The Fontan circulation is a fragile system in which imperfections at any one of multiple levels may compromise quality of life. Increased inferior vena caval (IVC) pressure itself may play some role in “Fontan failure”. The Fontan circulation is powered with a high speed injection jet shunt (IJS) drawing flow from the aortic arch, balanced by a fenestration to preserve the ratio of pulmonary flow (Qp) to systemic flow (Qs). The high-velocity jet causes flow entrainment, leading to a significant reduction of upstream pressure. We describe a tightly coupled multi-scale lumped parameter/computational fluids dynamics (LPM-CFD) model to validate this hypothesis. Methods: A synthetic 3D CAD model of the fenestrated total cavopulmonary connection (TCPC) was generated, with average dimensions matching those of a 2-4 yo patient. The prescribed cardiac output is of about 2.3L/min. The detailed 3D pulsatile hemodynamics in the fluid domain are modeled as unsteady, turbulent and incompressible. Blood is assumed to be non-Newtonian. Turbulence is approximated using a large eddy simulation (LES) approach. Potential optimal IJS configurations were determined by with a parametric sweep of several geometric design parameters such as TCPC morphology, shunt diameter and location, and fenestration diameter and location. The effects of the IJS implementation on IVC pressure with a fenestration and systemic oxygen saturation were calculated using a tightly coupled LPM-CFD. Results and Discussion: A set of baseline simulations representing a failing Fontan, with elevated IVC pressure (+17.8mmHg). Enlargement of the fenestration to 7 mm results in a 3 mm Hg IVC pressure drop but also significant reduction in systemic oxygen saturation (assuming a 96% pulmonary venous O2 saturation level). Addition of an IJS (2mm nozzle) to this model preserves the IVC pressure drop of 3.2mmHg but improves systemic oxygen saturation with only a small additional volume load to the ventricle (CO/Qs = 1.2). Conclusions: This study demonstrates the potential salutary effect of the IJS on the Fontan circulation. Further exploration of adjustable anatomic and parameters are needed to further reduce IVC pressure and improve systemic saturation.

Treatment of multiple huge liver cysts in a hybrid operating room: a case report

BackgroundLiver cysts are common, with most cases being asymptomatic. In symptomatic cases, the disease is amenable to treatment. However, huge or multiple liver cysts with vascular narrowing and associated systemic symptoms are extremely rare. Furthermore, the performance of a reliable and effective surgery in such cases remains a major problem. Here, we report a case of multiple giant liver cysts with impaired blood flow surgically treated in a hybrid operating room.Case presentationA 73-year-old male presented to a previous doctor with leg edema and dyspnea on exertion; computed tomography revealed that the cause complaint was right lung and heart compression and inferior vena cava (IVC) stenosis due to huge liver cysts in the caudal lobe. The patient was referred to our hospital because of disease recurrence despite percutaneous aspiration of the cyst. Multiple liver cysts were observed in addition to the drained cysts, two of which were located on both sides of the IVC and caused IVC stenosis. We performed open surgery for the liver cysts and used the hybrid operating room for intraoperative IVC angiography and measuring the hepatic vein and portal vein (PV) pressure. We performed unroofing of the hepatic cyst and cauterization of the cyst wall on the hepatic side. Angiography was performed before and after unroofing of the liver cysts, and IVC stenosis release was confirmed. IVC pressure measured at the peripheral side of the stenosis and PV pressures were continuously measured during surgery and were confirmed to have decreased during the opening of the liver cysts. The patient had a good postoperative course and was discharged on the 10th postoperative day. No recurrence was observed 6 months postoperatively.ConclusionsCyst unroofing surgery using angiography in a hybrid operating room is a useful treatment for deep hepatic lesions in that vascular stenosis improvement can be intraoperatively confirmed. Moreover, in cases wherein the cyst compresses the vasculature, intraoperative monitoring of IVC and PV pressures can be used to prove that the liver cyst is hemodynamically involved.

Not All Piggybacks Are Equal: A Retrospective Cohort Analysis of Variation in Anhepatic Transcaval Pressure Gradient and Acute Kidney Injury During Liver Transplant.

Complete inferior vena cava clamping in cavalreplacement during livertransplantis associated with substantial physiological derangement and postoperative morbidity. Partial clamping in the piggyback technique may be relatively protective, but evidence is lacking. Having observed substantial variation in transhepatic inferior vena cava pressure gradient with piggyback, we hypothesized that the causative mechanism is the extent of caval clamping rather than the surgical approach. We used internal jugular and femoral catheters to estimate suprahepatic and infrahepatic inferior vena cava pressures during clamping. Pressure gradients were calculated, and distributions were compared by surgical technique. We estimated adjusted odds ratios for pressure gradient on acute kidney injury at 72 hours. In 115 case records, we observed substantial variation in maximum pressure gradient; median values were 18.0 mm Hg(interquartile range, 8.0-25.0 mm Hg) with the piggyback technique and 24.0 mm Hg (interquartile range, 19.5-27.0 mm Hg) with caval replacement. Incidence of acute kidney injury was 25% (29 patients). Pressure gradient was linearly associated with probability of acute kidney injury (odds ratio, 1.06; 95% CI, 1.01-1.13). We report 2 novel findings. (1) Anhepatic inferior vena cavapressuregradient variedsubstantially in individuals undergoing piggyback, and (2) gradient was positively associatedwith early acute kidney injury. We hypothesize that this (unmeasured) variation explains the conflictingfindings ofprevious studies that compared surgical techniques. Also, we propose that caval pressure gradient could be routinely assessed to optimize real-time piggyback clamp position during livertransplant surgery.

TUBULOINTERSTITIAL INJURY WAS SUPPRESSED BY INHIBITION OF PLATELET-DERIVED GROWTH FACTOR PATHWAY IN RAT RENAL VENOUS CONGESTION MODEL

Objective: Increased central venous pressure in congestive heart failure is responsible for renal dysfunction. Pericytes contribute to the renal myofibroblast pool in renal fibrogenesis via pericyte-myofibroblast transition (PMT), and their detachment of from capillaries might trigger capillary rarefaction. We recently created a novel rat renal congestion model by ligation of the inferior vena cava (IVC) between the renal veins, resulting high renal interstitial hydrostatic pressure, tubulointerstitial injury and PMT. In this model, platelet-derived growth factor receptors (PDGFRs), which are PMT indicators, were upregulated. Thus we examined the effect of imatinib, a PDGFR inhibitor, for renal injury. Design and method: The inferior vena cava (IVC) between the renal veins was ligated by suture in male Sprague-Dawley rats to increase upstream IVC pressure and induce congestion only in the left kidney. Imatinib mesylate (20 mg/kg) or saline were injected intraperitoneally every day from one day before the operation. Both the right control kidney and the left congested kidney were obtained 3 days after the surgery and were weighted. The expression of renal injury marker and PDGFRs were assessed by quantitative reverse transcription-polymerase chain reaction, western blot and immunohistochemistry. The vascular structure of the kidneys was observed using micro-computed tomography (μCT) and low-vacuum scanning electron microscopy (LV-SEM). Results: Kidney weight was significantly increased in the left congested kidneys, and ameliorated by imatinib administration. However, μCT and LV-SEM results showed the maintained congestive state even in imatinib administration. Renal injury and fibrosis were observed in the congested kidneys, and imatinib significantly suppressed renal injury and fibrosis around the vasa recta. Conclusions: These results suggest that the inhibition of the PDGFRs pathway could suppress the renal fibrosis after PMT in heart failure-derived renal congestion. This mechanism could be a candidate therapeutic target for renoprotection against heart failure.

A225 INFERIOR VENA CAVA STENOSIS AFTER HEPATIC LOBECTOMY: A RARE CAUSE OF PORTAL HYPERTENSION AND REFRACTORY ASCITES

Abstract Background Inferior vena cava (IVC) stenosis is a rare occurrence in post-liver transplant patients, affecting less than 3% of recipients. IVC stenosis is rarely described in non-transplant patients or considered in the differential of portal hypertension and refractory ascites. Patients with IVC stenosis may experience lower extremity edema, dyspnea, ascites and other signs of portal hypertension. Aims We describe a case of portal hypertension and refractory ascites secondary to IVC stenosis following hepatic lobectomy. Methods Case report. Results We report a 61-year-old woman with a history of diabetes, obesity status post sleeve gastrectomy and solitary neuroendocrine tumor of the right hepatic lobe, adjacent to the porta hepatis with no evidence of metastasis. She underwent a laparoscopic right hepatectomy with wedge resection (&amp;lt;5 cm) in segment 4 to remove the neuroendocrine tumor in 2016. Surgery also included an intraoperative cholangiogram and placement of intra-ductal stent using endoscopic retrograde cholangiopancreatography (ERCP) technology as well as significant adhesiolysis along the IVC, right hepatic vein and biliary tract. In February 2020, the patient was referred to Hepatology for evaluation of new ascites. Imaging did not demonstrate evidence of tumor recurrence or features of cirrhosis but identified a new findings of portal hypertension and moderate ascites. Common causes of chronic liver disease were excluded and hepatic synthetic function was normal. Paracentesis revealed a high serum albumin ascites gradient (SAAG; 20 g/L) and a high ascitic fluid protein (34 g/L). Although these findings were suggestive of cardiac ascites, a 2D echocardiogram was normal. A trans-jugular liver biopsy was attempted in July 2020. The right atrial pressure was 8 mmHg and inferior vena cava (IVC) pressure was 22 mmHg at the level of the liver. Loss of pulsation suggested hemodynamically significant stenosis of the hepatic IVC. The wedged hepatic venous pressure was 3 mmHg and the calculated portal systemic gradient was 4 mmHg. A trans jugular biopsy failed due to unfavourable anatomy. These findings, taken in conjunction with previous results, suggested non-cirrhotic post-hepatic portal hypertension. Subsequent computed tomography imaging confirmed stenosis of the hepatic portion of the IVC and this was felt to be the ultimate cause of the portal hypertension. She has since been referred back to interventional radiology (IR) for consideration of balloon angioplasty dilation of the IVC stenosis as well as additional testing to determine if there is any underlying hepatic fibrosis related to congestive hepatopathy. Conclusions IVC stenosis post hepatic lobectomy is a rare phenomenon described in the literature but warrants high suspicion in cases of refractory ascites. Funding Agencies None