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.

• Keywords
• animal model, arteriovenous fistula, cerebral oxygenation, coronary artery flow, hyperkinetic circulation, tissue perfusion,
• Publication type
• Journal Article MeSH

AIMS: High-flow arteriovenous fistula (AVF) for haemodialysis leads to profound haemodynamic changes and sometimes to heart failure (HF). Cardiac output (CO) is divided between the AVF and body tissues. The term effective CO (COef) represents the difference between CO and AVF flow volume (Qa) and better characterizes the altered haemodynamics that may result in organ hypoxia. We investigated the effects of Qa reduction on systemic haemodynamics and on brain oxygenation. METHODS AND RESULTS: This is a single-centre interventional study. Twenty-six patients on chronic haemodialysis with high Qa (>1500 mL/min) were indicated for surgical Qa reduction for HF symptoms and/or signs of structural heart disease on echocardiography. The included patients underwent three sets of examinations: at 4 months and then 2 days prior and 6 weeks post-surgical procedure. Clinical status, echocardiographical haemodynamic assessment, Qa, and brain oximetry were recorded. All parameters remained stable from selection to inclusion. After the procedure, Qa decreased from 3.0 ± 1.4 to 1.3 ± 0.5 L/min, P < 0.00001, CO from 7.8 ± 1.9 to 6.6 ± 1.5 L/min, P = 0.0002, but COef increased from 4.6 ± 1.4 to 5.3 ± 1.4 L/min, P = 0.036. Brain tissue oxygen saturation increased from 56 ± 11% to 60 ± 9%, P = 0.001. CONCLUSIONS: Qa reduction led to increased COef. This was explained by a decreased proportion of CO running through the AVF in patients with Qa > 2.0 L/min. These observations were mirrored by higher brain oxygenation and might explain HF symptoms and improved haemodynamics even in asymptomatic high Qa patients.

• Keywords
• Arteriovenous fistula, Brain oximetry, Effective cardiac output, High-output heart failure,
• MeSH
• Arteriovenous Fistula * MeSH
• Arteriovenous Shunt, Surgical * MeSH
• Renal Dialysis MeSH
• Hemodynamics MeSH
• Humans MeSH
• Brain diagnostic imaging   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

Chronic kidney disease (CKD) leads to profound metabolic and hemodynamic changes, which damage other organs, such as heart and brain. The brain abnormalities and cognitive deficit progress with the severity of the CKD and are mostly expressed among hemodialysis patients. They have great socio-economic impact. In this review, we present the current knowledge of involved mechanisms.

• MeSH
• Renal Insufficiency, Chronic complications   pathology   MeSH
• Cognition Disorders etiology   pathology   MeSH
• Humans MeSH
• Brain diagnostic imaging   pathology   MeSH
• Risk Factors MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Review MeSH

A 79-year-old woman who was on chronic hemodialysis due to diabetic nephropathy and had previously undergo surgery for radiocephalic arteriovenous fistula (AVF) in her right wrist needed percutaneous transluminal angioplasty (PTA) for stenosis at the juxta-anastomotic access site. After successful PTA, the systemic blood pressure decreased from 144/93 mm Hg to 117/67 mm Hg in response to the increase in AVF blood flow. Furthermore, the regional oxygen saturation (rSO2) value in her dorsal hand decreased from 67.9% to 64.9% and, simultaneously, the cerebral rSO2 decreased from 63.6% to 60.1%. Our experience indicates that the PTA procedure may affect the rapid deterioration of systemic oxygenation, including that in the hand and brain, in association with the increase in the AVF blood flow and change in systemic circulation.

• Keywords
• Arteriovenous fistula, Cerebral oxygenation, Hand oxygenation, Hemodialysis, Hemodynamic instability, Percutaneous transluminal angioplasty,
• Publication type
• Journal Article MeSH
• Case Reports MeSH