Arteriovenous Shunts In Patients Research Articles

Diagnostic performance of dynamic 3D magnetic resonance angiography in daily practice for the detection of intracranial arteriovenous shunts in patients with non-traumatic intracranial hemorrhage.

Identification of treatable causes of intracranial hemorrhage (ICH) such as intracranial arteriovenous shunt is crucial to prevent recurrence. However, diagnostic approaches vary considerably across centers, partly because of limited knowledge of the diagnostic performance of first-line vascular imaging techniques. We assessed the diagnostic performance of dynamic three-dimensional magnetic resonance angiography (dynamic 3D MRA) in daily practice to detect intracranial arteriovenous shunts in ICH patients against subsequent digital subtraction angiography (DSA) as reference standard. We reviewed all adult patients who underwent first-line dynamic 3D MRA and subsequent DSA for non-traumatic ICH between January 2016 and September 2021 in a tertiary center. Sensitivity, specificity, accuracy, positive and negative predictive values of dynamic 3D MRA for the detection of intracranial arteriovenous shunt were calculated with DSA as reference standard. Among 104 included patients, 29 (27.9%) had a DSA-confirmed arteriovenous shunt [19 pial arteriovenous malformations, 10 dural arteriovenous fistulae; median onset-to-DSA: 17 (IQR: 3-88) days]. The sensitivity and specificity of dynamic 3D MRA [median onset-to-dynamic 3D MRA: 14 (3-101) h] for the detection of intracranial arteriovenous shunt were 66% (95% CI: 48-83) and 91% (95% CI: 84-97), respectively. The corresponding accuracy, positive and negative predictive values were 84% (95% CI: 77-91), 73% (95% CI: 56-90), and 87% (95% CI: 80-95), respectively. This study suggests that although first-line evaluation with dynamic 3D MRA may be helpful for the detection of intracranial arteriovenous shunts in patients with ICH, additional vascular imaging work-up should not be withheld if dynamic 3D MRA is negative. Comparative prospective studies are needed to determine the best imaging strategy to diagnose arteriovenous shunts after non-traumatic ICH.

Clinical and Haemodynamic Effects of Arteriovenous Shunts in Patients with Heart Failure with Preserved Ejection Fraction.

The arteriovenous shunt (AVS) is the most commonly used vascular access in patients receiving regular haemodialysis. The AVS may have a significant haemodynamic impact on patients with heart failure. Many studies have sought to understand the effect of AVS creation or closure on heart structure and functions, most of which use non-invasive methods, such as echocardiography or cardiac MRI. Data are mainly focused on heart failure with reduced ejection fraction and there are limited data on heart failure with preserved ejection fraction. The presence of an AVS has a significant haemodynamic impact on the cardiovascular system and it is a common cause of high-output cardiac failure. Given that most studies to date use non-invasive methods, invasive assessment of the haemodynamic effects of the AVS using a right heart catheter may provide additional valuable information.

Abstract 109: Non-invasive Detection of Capillary Arteriovenous Shunting in Patients With Sickle Cell Anemia

Introduction: High blood velocity can cause rapid erythrocyte transit through capillaries, reducing efficiency of oxygen delivery to tissue (capillary arteriovenous shunting). Arterial spin labeling (ASL) is an MRI technique that utilizes magnetic labeling of arterial blood water for CBF quantitation. Labeled water that traverses capillaries without exchanging with tissue leads to hyperintense venous signal indicative of arteriovenous shunting. We hypothesized that venous hyperintensity is present in sickle cell anemia (SCA) adults, correlates with flow velocity, and corresponds with clinical impairment and oxygen extraction fraction (OEF). Methods: ASL for shunting determination, TRUST for OEF measurement, phase contrast angiography for velocity assessment, and FLAIR / MRA for infarct / vasculopathy evaluation were performed at 3T in adults with SCA (n=36) and age- and race-matched controls (n=11). Three reviewers assessed for hyperintensity in the superior sagittal sinus on ASL images (Fig) and assigned scores of 0 (none), 1 (mild, focal), 2 (significant, focal), or 3 (significant, diffuse). Shunting scores were compared with the presence of clinical impairment (prior infarcts, stenosis>50%, or severe disease requiring transfusions) and OEF. Results: Interobserver agreement was excellent (Fleiss’ κ=0.91). Consensus shunting score in SCA adults (1.2±1.1) was higher (p<0.01) than controls (0.1±0.3), Median age 27.6 y, 57% F. Elevated shunting scores were observed in SCA adults with (1.23±1.07) vs. without (1.07±1.16) clinical impairment. A trend (p=0.068) for elevated OEF was observed in those with shunting scores ≥2 (0.44±0.07) vs. those with shunting scores ≤1 (0.40±0.07). Cervical flow velocity was elevated in subjects with shunting scores ≥2 (30.2±4.8 cm/s) vs. ≤1 (25.3±4.8 cm/s). Conclusion: Venous hyperintensity in ASL images may indicate capillary arteriovenous shunting and may reflect higher clinical impairment and elevated OEF.

Evaluation of Arteriovenous Shunting in Patients With End-Stage Liver Disease: Potential Role of Early Right Heart Catheterization

BackgroundIn patients with end-stage liver disease (ESLD), the presence of hypoxemia suggests the presence of intrapulmonary oxygen shunting (IPS) and/or transatrial shunting. Early identification of each is imperative to avoid potentially fatal peritransplantation complications and appropriately prioritize patients for liver transplantation (LT). The aim of this work was to compare the sensitivity of transthoracic echocardiography (TTE) and right heart catheterization (RHC) with intracardiac echocardiography (ICE) for identifying the etiologies of resting hypoxemia in patients with ESLD being evaluated for LT. MethodsRecords of 28 patients with ESLD and resting hypoxemia who underwent TTE with bubble study and RHC/ICE were reviewed. Patients with a patent foramen ovale (PFO) were compared with non-PFO patients to determine diagnostic accuracy of TTE with bubble study versus RHC/ICE. ResultsTTE with bubble study diagnosed PFO, IPS, and pulmonary hypertension (PH), respectively, with sensitivities of 46%, 41%, and 25% and specificities of 46%, 45%, and 80% compared with RHC/ICE. Although IPS detected by RHC/ICE was more common in patients without a PFO (92%), 5 patients with a PFO (33%) also had IPS (P = .002). Isolated PH was detected exclusively in patients with a PFO (5/15; 33%). ConclusionsTTE with bubble study is neither sensitive nor specific to exclude a PFO in patients with ESLD. RHC/ICE is a safe and accurate diagnostic/interventional modality in this group of patients and is useful to diagnose other comorbidities, such as IPS and PH, that may coexist and contribute to resting hypoxemia.

TCTAP A-172 Feasibility and Safety of Right Heart Catheterization via Arteriovenous Shunts in Patients on Maintenance Hemodialysis: A Prospective Study

TCTAP A-172 Feasibility and Safety of Right Heart Catheterization via Arteriovenous Shunts in Patients on Maintenance Hemodialysis: A Prospective Study

Transcatheter Arterial Embolization of Hepatic Arteriovenous Shunts in Patients with Hepatocellular Carcinoma

Transcatheter Arterial Embolization of Hepatic Arteriovenous Shunts in Patients with Hepatocellular Carcinoma

Onyx embolization of high flow spontaneous cervical vertebral arteriovenous fistula

High flow spontaneous vertebral arteriovenous shunts in patients with fibromuscular dysplasia (FMD) are rare. We present a 59-year-old woman with progressive dizziness, pre-syncopal episodes and tinnitus. Catheter-based angiography identified features of FMD and a high flow, right cervical vertebral artery arteriovenous shunt. Onyx-18 embolization (Onyx liquid embolic system, eV3, Irvine, CA, USA) of the principal draining veins was performed with initial detachable coil placement. Complete disconnection of the shunt was achieved without sacrifice of the parent vertebral artery. Thus, spontaneous high flow vertebral arteriovenous shunts can be successfully occluded with Onyx/detachable coil embolization of the principal recipient veins. To our knowledge, this is the first report of Onyx embolization of the recipient veins with shunt disconnection and preservation of the affected vertebral artery in a patient with FMD.

Onyx Embolization of High-Flow Spontaneous Cervical Vertebral Arteriovenous Fistula

High-flow spontaneous vertebral arteriovenous shunts in patients with fibromuscular disease (FMD) are rare. Onyx embolization of the recipient veins with shunt disconnection and preservation of the affected vertebral artery in a patient with FMD has not been reported. A 59-year-old female presented with progressive dizziness, pre-syncopal episodes, and tinnitus. Catheter-based angiography identified features of fibromuscular dysplasia and a high-flow right cervical vertebral artery arteriovenous shunt. Onyx embolization of the principle draining veins was performed with initial detachable coil placement. Complete disconnection of the shunt was achieved without sacrifice of the parent vertebral artery. Spontaneous high-flow vertebral arteriovenous shunts can be successfully occluded with Onyx/detachable coil embolization of the principle recipient veins.

Three-dimensional conformal radiotherapy for the treatment of arteriovenous shunting in patients with hepatocellular carcinoma

The objective of this study is to evaluate the efficacy of radiotherapy for the treatment of arteriovenous shunting (AVS) in patients with hepatocellular carcinoma (HCC). Between November 1997 and April 2005, 20 HCC patients with AVS were referred to our department for radiotherapy. The radiation was delivered with 10-15 MV X-ray given 5 days per week at 2 approximately 2.5 Gy per fraction. Total doses ranged from 45 to 64 Gy (median dose 60 Gy). The patients were followed up with color Doppler sonography. When non-invasive imaging suggested obliteration, X-ray angiography was performed to verify the results. Four of the 20 AVS proved to be completely obliterated at X-ray angiography in 1.9, 2.8, 1.8 and 2.9 months after radiotherapy. One of the remaining 16 showed obvious regression on Doppler sonography 0.5 months after radiotherapy, but X-ray angiography was not performed to verify the result. Radiation-related hepatic failure did not occur during the follow-up period. In conclusion, radiotherapy is a treatment alternative for AVS in HCC patients and gives patients with poor prognosis the chance to receive further transcatheter arterial embolization.

Sorbitol removal by the metastatic liver: a predictor of systemic toxicity of intra-arterial chemotherapy in patients with liver metastases

Background/Aim: Hepatic arteriovenous shunting in the metastatic liver reduces the advantages of intraarterial infusion of chemotherapeutic agents because of the passage of drugs into the systemic circulation. The aim of this study was to quantitatively assess spontaneous functional hepatic arteriovenous shunting in patients with liver metastases and to determine its implication in the increase in systemic toxic effects of intra-arterial infusion chemotherapy with floxuridine. Methods: Twenty-five patients who underwent implantation of arterial ports for regional chemotherapy of liver metastases were studied. Functional hepatic arterio-venous shunting was evaluated through the bioavailability of intra-arterially administered D-sorbitol, a safe, natural compound whose kinetic features make its hepatic clearance flow dependent. In addition, D-sorbitol hepatic clearance (a parameter reflecting functional liver blood flow) and common liver function tests were evaluated for each studied patient. Patients were then grouped with respect to the percentage of medically-assessed liver occupation by metastases and with respect to systemic toxicity of the chemotherapeutic treatment. Both univariate and multivariate analyses by Student's t-test and stepwise logistic regression, respectively, were performed in both groups for each of the evaluated parameters (age, liver function tests, D-sorbitol hepatic clearance and arterial bioavailability). Results: Arterial bioavailability of D-sorbitol ranged between 0.05 and 0.72 and was significantly greater in patients with more than 50% liver occupation (0.39±0.19) compared with those with minor liver involvement (0.17±0.13; p=0.003); it was also significantly greater in patients experiencing high-grade systemic toxicity (0.40±0.19) compared with those with low-grade toxicity (0.16±0.11; p<0.001). Multivariate analysis showed that arterial bioavailability of D-sorbitol was the only parameter among those evaluated which was able to predict systemic toxicity of this kind of chemotherapy. Conclusions: Our results show that, in the metastatic liver, arterial bioavailability of D-sorbitol, an index of functional arteriovenous shunting, varies widely, is significantly greater in patients with massive liver occupation and it is a good predictor of systemic toxicity of intra-arterial regional chemotherapy with floxuridine.

Arteriovenous shunting in hepatocellular carcinoma: Its prevalence and clinical significance

Arteriovenous shunting has been reported in hepatocellular carcinoma (HCC) and is a recognized contraindication to treatment by transcatheter arterial chemoembolization. This study aims to determine the prevalence of arteriovenous shunting in patients presenting with HCC and the development of shunts in those with inoperable HCC being treated with repeated chemoembolization. In a group of 292 Chinese patients (251 men, 41 women; mean age 54.7 years) presenting with HCC, hepatic angiograms demonstrated arteriovenous shunting in 91 cases (31.2%); shunting into the portal vein was observed in 84 (28.8%) and shunting into the hepatic vein in seven (2.4%). The hepatic angiograms of a separate group of 171 Chinese patients (144 men, 27 women: mean age 55.4 years) undergoing chemoembolization for inoperable HCC were analysed. Arteriovenous shunting developed during treatment in 20 patients (11.7%). Of these 20 patients, one had shunting into the hepatic vein while 19 (11.1%) had arterioportal shunting. Arteriovenous shunting occurred through the tumour or portal vein tumour thrombus in 13 patients, and occurred at sites remote from the tumour in the other seven patients. Shunting disappeared on repeat angiograms in three patients. Various postulated mechanisms responsible for arteriovenous shunting in HCC are reviewed. The recognition of development of arteriovenous shunting during chemoembolization of HCC is important as it has a direct bearing on patient management and prognosis.

Arteriovenous shunting in patients with colorectal liver metastases

The outlook for patients with colorectal liver metastases is poor. Microspheres have been combined with cytotoxics and administered via the hepatic artery in an attempt to improve tumour drug exposure within the liver. However, it has been suggested that arteriovenous connections might occur in association with intrahepatic tumours causing loss of regional advantage, and that the administration of microspheres further exacerbates arteriovenous shunting. In seven patients with colorectal liver metastases, base-line shunting was measured using a tracer quantity of radio-labelled albumin microspheres. The shunted fraction of a 'therapeutic quantity' of microspheres was subsequently measured in the same group of patients using albumin microspheres carrying a different radio-label. Base-line shunt for 0.5 x 10(6) microspheres was found to be 2.2 +/- 1.8% (mean +/- s.d.); the percentage shunt of a therapeutic quantity (40-80 x 10(6)) of microspheres was 3.0 +/- 0.8%. We conclude that arteriovenous shunting in patients with colorectal liver metastases is minimal, and is not significantly increased by the administration of therapeutic quantity of microspheres during regional chemotherapy.

The use of two‐dimensional contrast echocardiography in patients with portal hypertension for the detection of cardiac chamber abnormalities and pulmonary arteriovenous shunts

To study the cardiac chamber abnormalities and presence of pulmonary arteriovenous shunts in patients with non‐cirrhotic portal fibrosis (NCPF), two‐diemensional echocardiography was carried out in 14 patients. Eleven patients with cirrhosis of the liver and seven patients with extrahepatic obstruction were also studied. No patient had organic heart disease, clinical cyanosis, significant anaemia, or features of hepatic decompensation. Significant enlargement of left atrial, left ventricular and right ventricular chambers was seen in 64%, 57% and 14% of NCPF patients, respectively. There was, however, no significant difference in the frequency of cardiac chamber enlargement in patients with NCPF compared with the other two groups of patients. Though reduced left ventricular ejection fraction (&lt; 60% normal) was more commonly seen in patients with NCPF (35.7%) than in patients with cirrhosis (18.2%), the difference was not significant. No patient with extrahepatic obstruction had reduced ejection fraction. Except for one patient with cirrhosis, echocardiography with saline infusion failed to reveal intrapulmonary shunts in any patient. It is concluded that cardiac chamber abnormalities were seen in a significant proportion of patients with NCPF, but, none of them showed pulmonary arteriovenous shunts as studied by contrast echocardiography.

Urokinase treatment for arteriovenous fistulae declotting in dialyzed patients.

Urokinase treatment, previously employed with success in the declotting of deep venous thrombosis and arteriovenous shunts in patients undergoing regular dialytic treatment (RDT), was used in 23 cases of arteriovenous fistula thrombotic occlusion in 18 RDT patients. The treatment was successful in 65.2% of the cases without any negative side effects, except 1 case which may have developed a pulmonary embolism. Patients with severe hypofibrinolysis may need larger doses or may have a recurrence of the thrombotic episode. All therapeutic failures correlated with the presence of fibrosis or sclerosis.

Quantification of Arteriovenous Shunting in Renal Cell Carcinoma

Arteriovenous shunting was quantitated with 20 plus or minus 10 µ99mtechnetium human albumin microspheres in 12 patients with angiographically hypervascular renal cell carcinomas. Arteriovenous shunting was diagnosed angiographically when the renal vein was opacified during the arterial phase. With use of an angiographic catheter 2 to 3 mCi. 99mtechnetium human albumin microspheres were first injected into the renal artery directly supplying the tumor. Thereafter, 0.5 to 1 mCi. microspheres were injected into the inferior vena cava. Scintillation counts over the right lung were obtained immediately after each injection. The ratio between the 2 counts established the rate of tumor shunting after correction for dose difference and decay. Nine patients without angiographic evidence of arteriovenous shunting had mean shunt rates of 15 per cent, whereas 3 patients with angiographically visible shunting had significantly higher shunt rates of 57 per cent (p less than 0.001). It is concluded that angiography discovers only massive arteriovenous shunting in patients with renal cell carcinoma, whereas a fair degree of arteriovenous shunting may go undetected. The significance of minimal or moderate arteriovenous shunting in patients with renal cell carcinoma needs further investigation. The microsphere quantitation method can be applied routinely to angiography.

IMMOBILITY, HYPOXEMIA, AND PULMONARY ARTERIOVENOUS SHUNTING

Physiologic and pathologic effects of a systematic regimen of movement were compared with immobility in anesthetized, over-hydrated dogs. Immobile animals suffered early loss of oxygenating capability of the dependent lung that developed extensive atelectasis, hemorrhage, and pulmonary edema. A regimen of movement to alternate lateral positions every 30 minutes preserved oxygenating ability of both lungs, while hourly changes restored lost function and minimized the extent of pathologic findings in random zones of the lungs. Active regimens of movement were observed to prevent or relieve the arteriovenous shunting in patients. Pathophysiology was exaggerated in the dependent lung and reduced by change to the alternate position. Immobility, a critical factor in the genesis of hypoxemia, must be replaced by planned, systematic antigravity changes in position to maintain optimal lung mechanics and airway resistance and to prevent wasted work of the heart.

Immobility, hypoxemia, and pulmonary arteriovenous shunting.

Physiologic and pathologic effects of a systematic regimen of movement were compared with immobility in anesthetized, over-hydrated dogs. Immobile animals suffered early loss of oxygenating capability of the dependent lung that developed extensive atelectasis, hemorrhage, and pulmonary edema. A regimen of movement to alternate lateral positions every 30 minutes preserved oxygenating ability of both lungs, while hourly changes restored lost function and minimized the extent of pathologic findings in random zones of the lungs. Active regimens of movement were observed to prevent or relieve the arteriovenous shunting in patients. Pathophysiology was exaggerated in the dependent lung and reduced by change to the alternate position. Immobility, a critical factor in the genesis of hypoxemia, must be replaced by planned, systematic antigravity changes in position to maintain optimal lung mechanics and airway resistance and to prevent wasted work of the heart.

Decreasing Pain in Arteriovenous Cannulograms

Abstract Angiography is frequently used to demonstrate obstructing lesions in arteriovenous shunts in patients on chronic hemodialysis. Injection of the arterial side is extremely painful. Immediate aspiration of blood following arterial injection of contrast medium significantly decreases patient discomfort without sacrificing the quality of the examination.

Fibrinolytic activity of shunt arterial blood in patients on regular dialysis treatment.

When fibrinolytic activity of arterial blood from arteriovenous shunts in patients on regular dialysis treatment was compared with arterial blood of age-matched subjects without renal disease no statistically significant difference was observed. It is suggested that this may be due either to the damaged kidneys continuing to produce plasminogen activator or to the smaller amount of activator produced by the diseased kidneys being compensated by a reduced removal of it in the lungs.