High-flow Arteriovenous Fistula Research Articles

Hemodialysis Patients with High-Flow Arteriovenous Fistulas: An Evaluation of the Impact on Cardiac Function.

: Patients undergoing hemodialysis often experience changes in cardiac function when they have a high-flow arteriovenous fistula (AVF). This study aimed to assess the effect of high-flow AVFs on cardiac function in patients undergoing hemodialysis. : A longitudinal study was conducted on hemodialysis patients with high-flow AVFs. Echocardiographic parameters, such as left ventricular ejection fraction (LVEF), left atrial diameter (LAD), left ventricular end-diastolic dimension (LVEDD), right ventricular end-diastolic dimension (RVEDD), inferior vena cava diameter (IVCD), systolic blood pressure, and diastolic blood pressure, were measured and compared before and after AVF creation. : One hundred hemodialysis patients with high-flow AVFs (mean age: 55.95±13.39 years, mean body mass index: 24.71±3.43 kg/m²) were studied. LVEF significantly decreased (51.10%±5.39% to 47.50%±5.79%), while LAD, LVEDD, and IVCD significantly increased after AVF creation (P<0.05). Systolic (132.49±16.42 mmHg to 146.60±17.43 mmHg) and diastolic (79.98±8.40 mmHg to 83.33±9.68 mmHg) blood pressure substantially rose post-fistularization (P<0.001). Notably, LVEF reduction was more significant in brachio-cephalic AVFs (46.29%±4.24%) compared to distal radio-cephalic or snuffbox AVFs (49.17%±7.15%) (P=0.014). : High-flow AVFs can significantly affect echocardiographic parameters in hemodialysis patients, thereby increasing the risk of cardiac failure. Close cardiac monitoring may be necessary for early intervention. Distal AVFs may be preferable in patients with decreased cardiac function.

Effect of flow reduction surgery in a patient with high flow arteriovenous fistula with aortic dissection using 4D flow magnetic resonance imaging: A case report.

This study aimed to investigate cardiovascular function in a patient with high-flow arteriovenous fistula (AVF) who underwent aortic dissection (AD) using four-dimensional (4D) flow magnetic resonance imaging (MRI) as well as analyze the effect of flow reduction surgery on AD. On March 12, 2017, a 60-year-old woman underwent emergency surgery for AD. After that, she experienced acute kidney injury, and hemodialysis was initiated. On April 24, 2017, a left brachiocephalic arteriovenous fistula (AVF) was created to facilitate her dialysis. However, after 5 years, the patient presented with a high-flow AVF, and a flow reduction surgery was performed on March 11, 2022. To evaluate the procedure's effectiveness, we measured the changes in left ventricular (LV) function and blood flow in the aorta and vascular access before and after surgery using 4D flow MRI. Notable changes were observed in LV function, blood flow in the aorta before and after the surgery, and maximum velocity and flow volume after surgery. During the 6-month follow-up after the surgery, the maximum velocity and flow volume in the aorta and vascular access were reduced; also, indicators such as LV volume, cardiac output, cardiac index, and LV mass were improved. In patients with high-flow AVF, flow reduction surgery should be considered as it may improve LV function and reduce the risk of AD recurrence by lowering the flow volume of the aorta.

Systemic vascular resistance predicts high-output cardiac failure in patients with high-flow arteriovenous fistula.

Patients with high-flow arteriovenous (AV) access are at risk of developing high-output cardiac failure (HOCF) and subsequent hospitalization. However, diagnosing HOCF is challenging and often requires invasive procedures. The role of systemic vascular resistance (SVR) in diagnosing HOCF is underestimated, and its predictive value is limited. Our study aims to identify non-invasive risk factors for HOCF to facilitate early diagnosis and timely surgical interventions. We included 109 patients with high-flow AV access who underwent serial echocardiography. The retrospective cohort was divided into two groups based on their hospitalization due to HOCF. The two groups were matched for age and gender. After a mean follow-up of 25.1months, 19 patients (17.4%) were hospitalized due to HOCF. The two groups had similar baseline characteristics. However, the HOCF group had a higher value of vascular access blood flow (Qa) (2168±856 vs. 1828±617mL/min; P=0.045). Echocardiographic analysis revealed that the HOCF group had more pronounced left ventricular diastolic dysfunction (E/e': 21.1±7.3 vs. 16.2±5.9; P=0.002), more severe pulmonary hypertension (right ventricular systolic pressure: 41.4±16.7 vs. 32.2±12.8; P=0.009), a higher Doppler-derived cardiac index (CI) (4.3±0.8 vs. 3.7±1.1; P=0.031), and a lower Doppler-derived estimated SVR (eSVR) value (5.5±0.3 vs. 6.9±0.2; P=0.002) than the non-HOCF group. Using multivariable Cox regression analysis, a low eSVR value (<6) emerged as an independent predictor of HOCF hospitalization with a hazard ratio of 9.084 (95% confidence interval, 2.33-35.39; P=0.001). Receiver operating characteristic curve analysis indicated that CI/eSVR values more accurately predicted HOCF hospitalization [sensitivity: 94.7%, specificity: 51.0%, area under the curve (AUC): 0.75, P<0.001] than the Qa/cardiac output ratio (AUC: 0.50, P=0.955), Qa values≥2000mL/min (AUC: 0.60, P=0.181), and Qa values indexed for height in metres (AUC: 0.65, P=0.040). In patients with high-flow AV access, low eSVR values obtained through non-invasive Doppler echocardiography were associated with a high rate of HOCF hospitalizations. Therefore, routine eSVR screening in these patients might expedite the diagnosis of HOCF.

Anatomical considerations regarding a high-flow arteriovenous fistula below the conus medullaris in a patient with hereditary hemorrhagic telangiectasia: Case report.

Cauda equina radicular arteriovenous fistulas are rare "low flow" shunting lesions characterized by direct communication between the radicular artery and vein of a cauda equina nerve root. None have been associated with hereditary hemorrhagic telangiectasia and a high-flow cauda equina radicular arteriovenous fistula has never been reported. We present a unique case of a high-flow cauda equina radicular arteriovenous fistula in a patient with hereditary hemorrhagic telangiectasia. Marked flow-induced vascular remodeling posed significant diagnostic and therapeutic challenges which will be highlighted in this report. A 39-year-old female with genetically confirmed hereditary hemorrhagic telangiectasia presented with progressive thoracic myelopathy secondary to a high-flow single-hole arteriovenous fistula below the conus. The feeding artery, arising from the anterior spinal artery, and draining vein had a paramedian course, favoring the diagnosis of a cauda equina radicular arteriovenous fistula (supplied by a proximal radicular artery) over a filum terminale arteriovenous fistula. Transarterial embolization was attempted but significant elongation and tortuosity of the anterior spinal artery precluded microcatheter access to the fistulous point. Surgical disconnection was successfully performed. The intraoperative findings supported the diagnosis of cauda equina radicular arteriovenous fistula. Delayed neurologic deterioration secondary to overshooting venous thrombosis was observed. She recovered after the initiation of therapeutic anticoagulation. To the best of our knowledge, we hereby report the first high-flow cauda equina radicular arteriovenous fistula. The accurate differentiation of cauda equina radicular arteriovenous fistula from filum terminale arteriovenous fistulas, while challenging, is important to avoid treatment-related complications. Careful preoperative planning, the use of specialized endovascular and surgical techniques, and meticulous postoperative care can ensure the safe and complete disconnection of high-flow cauda equina radicular arteriovenous fistulas.

Comparing the hemodynamic effect of a large arteriovenous fistula during high and low cardiac output states.

Background: A large arteriovenous fistula (AVF) is a low-resistant circuit that affects organ perfusion and systemic hemodynamics even in standard conditions. The extent of its' effect in critical states has not been elucidated yet. We used norepinephrine to create systemic vasoconstriction, dobutamine to create high cardiac output, and rapid right ventricle pacing as a model of acute heart failure in a porcine model of high-flow AVF circulation. Methods: The protocol was performed on nine domestic female pigs under general anesthesia. AVF was created by connecting two high-diameter ECMO cannulas inserted in the femoral artery and vein. Continuous hemodynamic monitoring was performed throughout the protocol. Three interventions were performed-moderate dose of norepinephrine (0.25ug/kg/min), moderate dose of dobutamine (10ug/kg/min) and rapid right ventricle pacing to simulate low cardiac output state with mean arterial pressure under 60mmHg. Measurements were taken with opened and closed arteriovenous fistula. Results: Continuous infusion of norepinephrine with opened AVF significantly increased mean arterial pressure (+20%) and total cardiac output (CO) (+36%), but vascular resistance remained virtually unchanged. AVF flow (Qa) rise correlated with mean arterial pressure increase (+20%; R = 0.97, p = 0.0001). Effective cardiac output increased, leading to insignificant improvement in organ perfusion. Dobutamine substantially increased cardiac output with insignificant effect on AVF flow and mean arterial pressure. Carotid artery blood flow increased significantly after dobutamine infusion by approximately 30%, coronary flow velocity increased significantly only in closed AVF state. The effective cardiac output using the heart failure model leading to decrease of carotid artery flow and worsening of brain and peripheral tissue oximetry. AVF blood flow also dropped significantly and proportionally to pressure, but Qa/CO ratio did not change. Therefore, the effective cardiac output decreased. Conclusion: In abovementioned extreme hemodynamic conditions the AVF flow was always directly proportional to systemic perfusion pressure. The ratio of shunt flow to cardiac output depended on systemic vascular resistance. These experiments highlight the detrimental role of a large AVF in these critical conditions' models.

#5411 CARDIO-FISTULA RECIRCULATION REDUCTION IN OLDER ADULTS: IT'S NOT THAT EASY

Abstract Background and Aims Older adults are approximately 40% of all prevalent HD patients [ERA Annual report]. Cardiovascular disease is the leading cause of death in this cohort. It is well-known that the cardiotoxic effect of arterio-venous fistula (AVF) is fully realized when cardio-fistula recirculation (CFR) is above 20-30%. We believe that the reduction of AVF blood flow (Qa) in the elderly is often less effective than in the younger patients. Aim: to evaluate the outcomes of Qa reduction in the elder and the younger HD patients. Method The prospective cohort study included 21 patients over 60 years old and 36 patients under 60 years old: the median age was 74 years [IQR 69; 78, min-max 64-81] and 41 years [IQR 35; 45, min-max 31; 55], respectively. In all patients, GFR before reduction was more than 25%: 32.8% [IQR 29.2; 35.1, min-max 27.3; 38.9] and 33% [IQR 31; 35.125, min-max 27.1; 39.3], respectively. Qa reduction was performed by banding of the paraanastomotic AVF segment with intraoperative control (Doppler ultrasonography) until reaching Qa of 1.5 l / min or less. Results In all patients, we noted a significant (p&amp;lt;0.0001 in all cases) decrease in Qa as a result of the banding: in older adults from 2.1 l / min [IQR 1.9; 2.4, min-max 1.8; 2.8] to 1.2 l / min [IQR 1; 1.4, min-max 0.8; 1.5], delta Qa was -1 l / min [IQR -1.2; -0.9, min-max -1.5; -0.7], in younger patients from 2.8 l / min [IQR 2.5; 3.1, min-max 1.9; 3.5] to 1.3 l / min [IQR 1.1; 1.4, min-max 0.9; 1.5], -1.5 l / min [IQR -1.7; -1.3, min-max -2.3; -0.9], respectively. In both elder and younger patients, we noted a significant decrease in CFR - Fig. 1. However, after Qa reduction, only 5 of 21 elderly patients had CFR value less than 20%. Thus, 17 of 21 patients had CFR in the «gray zone» - 20-30%: 22.8% [IQR 21.85; 27.3, min-max 21; 29.2]. In younger patients, 25 of 36 had CFR less than 20% after Qa reduction, while 11 stayed in the «gray zone»: 21.15% [IQR 20.575; 22.3, min-max 20.3; 23.4]. The probability of reducing CFR to a safe level (less than 20%) after surgery was significantly less in the elder patients: RR = 0.3429 [95% CI 0.1495; 0.6852], p = 0.0011. We consider the lower baseline cardiac output in the elderly to be the main reason of the lower efficacy of Qa reduction: the difference between medians (older adults-younger patients before Qa reduction, Hodges-Lehmann method) was 1.9 l / min [95% CI 1.5; 2.4], p &amp;lt;0.0001. At the same time, Qa before reduction did not differ much between the older and the younger: 0.6 l / min [95% CI 0.4; 0.8], p &amp;lt;0.0001. Moreover, the reduction of Qa in elderly patients led to a decrease in the ejection fraction (EF), which was not noticed in young patients - Fig. 2. Notably, in all patients of both groups the initial value of the EF was more than 55%. We believe that this can be explained by an abrupt increase in afterload against the background of a decreased compensatory heart capability in the elderly. At the same time, decrease in the EF after Qa reduction in the elderly may indirectly indicate that conventional EF in the elderly is maintained by a presence of a high-flow AVF. Evaluation of EF against this background creates a putative picture of well-being and can mask the development of heart failure with reduced EF for a long time. Conclusion We noted a lower efficacy of Qa reduction as a method of reducing both cardio-fistula recirculation and cardiovascular risk in the elder patients compared to the younger patients on maintenance HD. Elder patients seem to require a different approach to reduce cardiovascular risk than younger patients.

Effect of proximal artery restriction on flow reduction and cardiac function in hemodialysis patients with high-flow arteriovenous fistulas

ObjectiveArteriovenous fistula is the preferred vascular access for hemodialysis patients. High-flow arteriovenous fistula may cause high-output heart failure. Various procedures are used to reduce high-flow arteriovenous fistula. This study aimed to assess the efficacy of proximal artery restriction combined with distal artery ligation on flow reduction for high-flow arteriovenous fistula and on cardiac function and echocardiographic changes in patients undergoing hemodialysis. MethodsA retrospective analysis was performed on data collected from the medical records of patients undergoing hemodialysis with heart failure and high-flow arteriovenous fistula between May 2018 and May 2021. Thirty-one patients were treated with proximal artery restriction (banding juxta-anastomosis of the proximal artery) combined with distal artery ligation (anastomosis distal artery ligation). Changes in the Acute Dialysis Quality Initiative Workgroup cardiac function class, blood pressure, and echocardiography before and 6 months after flow restriction were compared, and post-intervention primary patency was followed-up. ResultsThe technical success rate of the surgery was 100%, and no surgery-related adverse events occurred. Blood flow and blood flow/cardiac output decreased significantly after flow restriction. Blood flow decreased from 2047.21 ± 398.08 mL/min to 1001.36 ± 240.42 mL/min, and blood flow/cardiac output decreased from 40.18% ± 6.76% to 22.34% ± 7.21% (P < .001). Post-intervention primary patency of arteriovenous fistula at 6, 12, and 24 months was 96.8%, 93.5%, and 75.2%, respectively. The Acute Dialysis Quality Initiative Workgroup cardiac function class improved significantly after 6 months of flow restriction (P < .001). The systolic and diastolic left heart function improved, as evidenced by a significant decrease in left atrial volume index, left ventricular end-diastolic/end-systolic diameters, left ventricular end-diastolic volume, left ventricular mass index, cardiac output, and cardiac index and an increase in lateral peak velocity of longitudinal contraction, average septal-lateral s', and lateral early diastolic peak velocity after flow restriction (P < .05). Systolic pulmonary artery pressure decreased from 32.36 ± 8.56 mmHg to 27.57 ± 8.98 mmHg (P < .05), indicating an improvement in right heart function. ConclusionsProximal artery restriction combined with distal artery ligation effectively reduced the blood flow of high-flow arteriovenous fistula and improved cardiac function.

Impact and Management under Extracorporeal Circulation of a Patient with Renal Insufficiency on Dialysis with a High-Flow Arteriovenous Fistula in the Cardiac Surgery Department of the Angers Teaching Hospital about a Case and Review of the Literature

Arteriovenous fistulas have a substantial impact on systemic hemodynamics, however their effect on extracorporeal circulation is not well understood. We report our clinical observation on the management under extracorporeal circulation of a patient with renal insufficiency with a high-flow arteriovenous fistula. This is a 59-year-old man who was referred to us for surgical treatment of ischemic coronary artery disease in a context of anuric chronic renal failure. Hypothermia at 32°C is started from the start in CEC due to hyperflow at the level of the arteriovenous fistula. We performed two coronary artery bypasses of the marginal and IVA via the two internal thoracic arteries. The patient is hemofiltered in order to avoid hyperkalaemia and possibly avoid fluid overload related to filling per CEC. The clamping time was 71 minutes and the SCC lasted 141 minutes. There was no homologous transfusion in the operating room. It turns out that the input/output balance is zero at the end of the CEC. The postoperative course was simple.

Huge cerebral pial arteriovenous fistula in a newborn: illustrative case.

BACKGROUNDPediatric arteriovenous malformations (AVMs) and pial/dural arteriovenous fistulas (AVFs) are rare but life-threatening complications that can lead to congestive heart failure and hemorrhagic stroke in newborns and pediatric patients. The pronounced shunting in these conditions is associated with early complications and necessitates aggressive surgical management. Here, the authors describe endovascular treatment of an atypical cerebral pial AVF in a newborn.OBSERVATIONSThis AVF formed direct communication between a major cerebral artery (basilar artery) and a large draining vein (dilated deep cerebral vein). The authors performed earlier subtotal embolization of the AVF using 0.020-inch coils, which led to progressive thrombosis of the fistula with restoration of normal arterial blood flow. The patient was discharged 18 days after surgery, examination at 1.5 and 6 months showed magnetic resonance imaging signs of blood flow absence through the fistula and satisfactory condition of the infant without physical and mental developmental delay.LESSONSSubtotal coiling of a high-flow pial AVF in a newborn can result in a good clinical outcome.

High-flow arteriovenous fistula resulting from stingray injury.

Stingray punctures are relatively common in several coastal regions and may result in chronic wounds and disability due to injury and envenomation. Vascular complications are rare but can be severe. We describe a case of high-flow arteriovenous fistula resulting from a stingray injury that required a venous bypass.

High-flow arteriovenous fistula and myocardial fibrosis in hemodialysis patients with non-contrast cardiac magnetic resonance imaging.

BackgroundThe role of high-flow arteriovenous fistula (AVF) in cardiovascular morbidity in hemodialysis (HD) patients is very likely under-recognized. We assessed the relationship between high access flow (Qa) and myocardial fibrosis in HD patients.MethodsMyocardial fibrosis was assessed by native T1 relaxation times on non-contrast cardiac magnetic resonance imaging and a potential marker of fibrosis. Serum levels of galectin-3, N-terminal pro-B-type natriuretic peptide (NT-proBNP), and monocyte chemoattractant protein 1 (MCP-1) were measured in 101 HD patients who underwent regular monitoring of AVF Qa. A high-flow AVF was defined as a Qa >2 L/min.ResultsHemodialysis patients showed significantly higher galectin-3 value and increased T1 relaxation time compared to healthy volunteers, suggesting increased myocardial fibrosis in uremic cardiomyopathy. In HD patients, 20 (19.8%) had a Qa > 2L/min, and they had significantly higher cardiac output, cardiac index, left ventricular mass, and increased T1 times than those with a Qa ≤ 2 L/min. Also, serum galectin-3 and NT-proBNP levels were much higher in the high Qa group, indicating a close relationship between the high Qa, increased myocardial fibrosis, and the risk of heart failure (HF) in HD patients. It is interesting that a higher AVF Qa for myocardial fibrosis was independent of several traditional cardiovascular risk factors as well as serum levels of NT-proBNP and MCP-1.ConclusionsA supra-physiologically high Qa can be related to myocardial fibrosis and increased risk of HF in HD patients. Regular Qa monitoring could allow early detection of a high-flow AVF that could arise cardiac complications.

Embolisation of an aneurysmal high-flow renal arteriovenous fistula in a paediatric patient: simultaneous arterial and venous approach

BackgroundA large aneurysmal renal arteriovenous fistula (AVF) can cause hypokalaemic hypertension due to activation of renin-aldosterone system due to steal effect from renal parenchyma. In comparison to nephrectomy, endovascular embolisation of renal AVF is minimally invasive and can be nephron sparing, thus preserving renal function. However, such embolisation is technically challenging and can be associated with high risk of embolic migration.Case presentationWe present a case of successful embolisation of a large aneurysmal renal AVF in a 11-year-old girl. The AVF was initially treated with coil embolization via transarterial route, resulting in partial migration of coil into inferior vena cava. After removal of the migrated coil via transvenous snaring, coils were deployed simultaneously via transarterial and transvenous routes to prevent migration. AVF flow dampened but residual flow persisted at 1 month follow up. A second embolization session with additional coil deployment and N-butyl cyanoacrylate (NBCA) injection resulted in successful occlusion of the AVF. At 3 months follow up, the girl’s blood pressure and serum potassium level have normalized without need of antihypertensive agent or potassium supplements.ConclusionEndovascular embolisation can be an effective nephron sparing treatment for large aneurysmal renal AVF. This is particularly important in paediatric patients as most renal function can be preserved with their expected longer life span. Risk of coil migration can be controlled by simultaneous transarterial and transvenous deployment. Complete occlusion of AVF can be aided by additional use of NBCA.

Reduction of arteriovenous access blood flow in kidney transplant patients.

Cardiovascular disease is the most frequent cause of death in kidney transplant patients. High-flow arteriovenous fistula (AVF) increases cardiac output and may contribute to hyperkinetic heart failure. AVF follow-up is not implemented in kidney transplant patients. The aim of this study was to reduce AVF blood flow in a group of patients with a high-flow AVF following kidney transplantation to reduce cardiac strain. This prospective study was performed in kidney transplant patients who had a vascular access created before transplantation. The AVF of these patients was examined by ultrasound with a focus on AVF flow and brachial artery size. If high-flow AVF was detected, flow reduction was performed in the indicated group of patients. The study examined 164 patients, of whom 24 had a hyperfunctional AVF (14.8%). A total of 16 AVF flow reductions were performed, which led to an average decrease in cardiac index by 0.77 L/min/m2. Primary patency of the reconstructions was 93.33% after 12 months. All patients experienced a subjective improvement in dyspnea. Reduction in AVF flow leads to an improvement in the quality of life of kidney transplant patients. Maintaining a functional AVF is beneficial, especially for patients after repeated surgeries, where the option of creating an autologous AVF is limited.

MO793: AVF Blood Flow Reduction in the Older Adults

Abstract BACKGROUND AND AIMS Older adults are approximately 40% of all prevalent HD patients (ERA-EDTA Annual report, 2019). Cardiovascular disease is the leading cause of death in this cohort. It is well-known that the cardiotoxic effect of arterio-venous fistula (AVF) is fully realized when cardio-fistula recirculation (CFR) is above 20–30%. We believe that the reduction of AVF blood flow (Qa) in the elderly is often less effective than in younger patients. To evaluate the outcomes of Qa reduction in the elder and the younger HD patients. METHOD The prospective cohort study included 21 patients ˃ 60 years and 36 patients ˂60 years: the median age was 74 years [interquartile range (IQR) 69; 78, min-max 64–81] and 41 years (IQR 35; 45, min-max 31; 55), respectively. In all patients, glomerular filtration rate (GFR) before reduction was more than 25%: 32.8% (IQR 29.2; 35.1, min-max 27.3; 38.9) and 33% (IQR 31; 35.125, min-max 27.1; 39.3), respectively. Qa reduction was performed by banding of the para-anastomotic AVF segment with intraoperative control (Doppler ultrasonography) until reaching Qa of 1.5 L/min or less. RESULTS In all patients, we noted a significant (P &amp;lt; 0.0001 in all cases) decrease in Qa as a result of the banding: in older adults from 2.1 L/min (IQR 1.9; 2.4, min-max 1.8; 2.8) to 1.2 L/min (IQR 1; 1.4, min-max 0.8; 1.5), delta Qa was −1 L/min (IQR −1.2; −0.9, min-max −1.5; −0.7), in younger patients from 2.8 L/min (IQR 2.5; 3.1, min-max 1.9; 3.5) to 1.3 L/min (IQR 1.1; 1.4, min-max 0.9; 1.5), −1.5 L/min (IQR −1.7; −1.3, min-max −2.3; −0.9], respectively. In both elder and younger patients, we noted a significant decrease in CFR—Figure 1. However, after Qa reduction, only 5/21 elderly patients had CFR value less than 20%. Thus, 17/21 patients had CFR in the ‘gray zone’ —20–30%: 22.8% (IQR 21.85; 27.3, min-max 21; 29.2). In younger patients, 25/36 had CFR ˂ 20% after Qa reduction, while 11 stayed in the ‘gray zone’: 21.15% (IQR 20.575; 22.3, min-max 20.3; 23.4). The probability of reducing CFR to a safe level (˂ 20%) after surgery was significantly less in the elder patients: RR = 0.3429 [95% confidence interval (95%CI) 0.1495; 0.6852], P = 0.0011. We consider the lower baseline cardiac output in the elderly to be the main reason for the lower efficacy of Qa reduction: the difference between medians (older adults-younger patients before Qa reduction, Hodges–Lehmann method) was 1.9 L/min (95% CI 1.5; 2.4), P &amp;lt; 0.0001. At the same time, Qa before reduction did not differ much between the older and the younger: 0.6 L/min (95% CI 0.4; 0.8), P &amp;lt; 0.0001. Moreover, the reduction of Qa in elderly patients led to a decrease in the ejection fraction (EF), which was not noticed in young patients—Figure 2. Notably, in all patients of both groups, the initial value of the EF was more than 55%. We believe that this can be explained by an abrupt increase in afterload against the background of a decreased compensatory heart capability in the elderly. At the same time, a decrease in the EF after Qa reduction in the elderly may indirectly indicate that conventional EF in the elderly is maintained by a presence of a high-flow AVF. Evaluation of EF against this background creates a putative picture of well-being and can mask the development of heart failure with reduced EF for a long time. CONCLUSION We noted a lower efficacy of Qa reduction as a method of reducing both cardio-fistula recirculation and cardiovascular risk in the elder patients compared to the younger patients on maintenance HD. Elder patients seem to require a different approach to reduce cardiovascular risk than younger patients.

New Porcine Model of Arteriovenous Fistula Documents Increased Coronary Blood Flow at the Cost of Brain Perfusion.

Background: Arteriovenous fistulas (AVF) represent a low resistant circuit. It is known that their opening leads to decreased systemic vascular resistance, increased cardiac output and other hemodynamic changes. Possible competition of AVF and perfusion of other organs has been observed before, however the specific impact of AVF has not been elucidated yet. Previous animal models studied long-term changes associated with a surgically created high flow AVF. The aim of this study was to create a simple AVF model for the analysis of acute hemodynamic changes. Methods: Domestic female pigs weighing 62.6 ± 5.2 kg were used. All the experiments were held under general anesthesia. The AVF was created using high-diameter ECMO cannulas inserted into femoral artery and vein. Continuous hemodynamic monitoring was performed throughout the protocol. Near-infrared spectroscopy sensors, flow probes and flow wires were inserted to study brain and heart perfusion. Results: AVF blood flow was 2.1 ± 0.5 L/min, which represented around 23% of cardiac output. We observed increase in cardiac output (from 7.02 ± 2.35 L/min to 9.19 ± 2.99 L/min, p = 0.0001) driven dominantly by increased heart rate, increased pulmonary artery pressure, and associated right ventricular work. Coronary artery flow velocity rose. On the contrary, carotid artery flow and brain and muscle tissue oxygenation measured by NIRS decreased significantly. Conclusions: Our new non-surgical AVF model is reproducible and demonstrated an acute decrease of brain and muscle perfusion.

Fogarty-assisted transcatheter embolization of a large renal high-flow arteriovenous fistula

BackgroundRenal high-flow arteriovenous fistulas and its complications may involve high output heart failure, hematuria, hypertension or lethal hemorrhage.Case presentationThis case report covers the case of a 65-year-old male patient with a large renal high-flow arteriovenous fistula of the right kidney (RAVF), treated with balloon-assisted coil and liquid (n-Butyl Cyanoacrylate) embolization. By use of ballon-occlusion with an over-the-wire Fogarty catheter and advancement of a microcatheter through the lumen distal to the balloon during the transcatheter embolization of a high-flow RAVF, control of arterial blood flow is feasible by temporary occlusion of the afferent artery. This technique of flow modulation facilitates controlled deployment of embolization materials and decreases the risk of inadvertent distal embolization by use of only one 6-French (F) arterial sheath.ConclusionsBalloon-assisted embolization using a Fogarty occlusion catheter represents a feasible, safe and effective treatment option for the treatment of large, high-flow arteriovenous fistulas of the kidney.

[Hemodynamic and cardiovascular implications of arteriovenous fistulas in hemodialysis].

Arteriovenous fistula (AVF) remains the vascular access of choice in hemodialysis but generates cardiovascular constraints. Its creation immediately induces an increase in cardiac output. Increased venous return and subsequent volume overload lead to biventricular remodeling, and eventually to dysfunction. High-output heart failure (HOHF) caused by high-flow AVF is a recognized but not strictly defined clinical entity, based on the combination of hypervolemia with an elevated cardiac output. A Qa greater than 2 L/min is a risk factor for HOHF, particularly in susceptible patients. The most used flow reduction procedure is post-anastomotic vein caliber reduction by a banding technique, relieving symptoms and partially reversing previously induced structural abnormalities, but the benefit often remains limited in time.

Efficacy of the graft-covering technique for high-flow arteriovenous fistulas

Efficacy of the graft-covering technique for high-flow arteriovenous fistulas

Fatigue and Vertigo Caused by a Femoral Arterio-venous Fistula

An 83−year old patient who had undergone coronary artery bypass grafting and several cardiac catheterisations was referred with fatigue and vertigo. Physical examination revealed a thrill in the groin. Duplex ultrasound, computed tomography angiography, and (A) digital subtraction angiography showed a short neck, high flow arteriovenous fistula (AVF) between the deep femoral artery (DFA) and common femoral vein (CFV). Coil embolisation was planned but not carried out owing to the short fistula neck. (B) The AVF, which consisted of a small vein crossing the DFA, most probably caused post-catheterisation, was ligated successfully. The patient remains asymptomatic.Image 1

Transarterial Embolization of Intracranial Arteriovenous Fistulas with Large Venous Pouches in the Form of Venous Outlet Ectasia and Large Venous Varix or Aneurysm : Two Centers Experience.

ObjectiveThere are different types of cerebral vascular malformations. Pial arteriovenous fistulas (PAVFs) and dural arteriovenous fistulas (DAVFs) are two entities; they consist of one or more arterial connections to a single venous outlet without a true intervening nidus. The high turbulent flow of PAVFs and aggressive DAVFs with cortical venous reflux can result in venous outflow varix and aneurysmal dilatation. They pose a significant challenge to transvenous embolization (TVE), stereotactic radiosurgery, and surgical treatment. We aim to share our centers’ experience with the transarterial embolization (TAE) for arteriovenous fistulas (AVFs) with large venous pouches and to report the outcome. MethodsThe authors’ two institutions’ databases were retrospectively reviewed from February 2017 to February 2021. All patients with intracranial high flow PAVFs and aggressive DAVFs with venous outlet ectasia and large venous varix and were treated by TAE were included. ResultsFifteen patients harboring 11 DAVFs and four PAVFs met our inclusion criteria. All patients underwent TAE in 17 sessions. Complete angiographic obliteration was achieved after 14 sessions in 12 patients (80%). Four patients (25%) had residual after one TAE session. Technical failure was documented in one patient (6.7%). Fourteen patients (93.3%) had favorable functional outcome (modified Rankin score 0–2). ConclusionsTAE for high flow or aggressive intracranial AVFs is a safe and considerable treatment option, especially for those associated with large venous pouches that are challenging and relatively high-risk for TVE.