Pathophysiology of High Output Arteriovenous Fistula with Heart Failure: A Systematic Review and Meta-analysis

Introduction: Arteriovenous Fistula (AVF) is extensively used as vascular access for haemodialysis patients. It induces a high output state, which is associated with cardiac remodeling. With High Output Heart Failure (HOHF), the AVF occupies a low pressure; reduced vascular resistance and increased venous return. The High Output Arteriovenous Fistula with Heart Failure (HOHF-AVF) patients often undergo a comprehensive assessment of type of underlying diseases, the degree of vasodilatation along with laboratory investigations and cardiac imaging. Hence identification of the pathophysiological determinants of HOHF-AVF is intriguing. Aim: To identify the pathophysiological determinants of HOHF-AVF. Materials and Methods: This systematic review was conducted from May 2021 to December 2021 at the Department of Cardiovascular Surgery, Imperial College, United Kingdom. Randomised Controlled Trials (RCTs), cohort, case-control, cross-sectional and descriptive studies, conducted on adult patients who underwent AVF creation or ligation and addressed the pathophysiological determinants of HOHFAVF were included. Studies conducted among Paediatric cases, case reports, and case series were excluded. Medline (PubMed), EMBASE, ProQuest, and the Cochrane database were searched, by utilising the key words {[(“HOHF” OR “High output heart failure”) AND (“AVF” OR “Arteriovenous fistula”)] AND (“LV parameters” OR “Structural Characteristics” OR “Echocardiographic indices)}. The searches were restricted from January 2000 to October 2021 with studies published in the English language. All the included studies were subjected to critical appraisal using the “Cochrane risk of bias assessment tool” for RCTs, and the “Joanna Briggs Institute (JBI) checklist” for cohort, case-control, cross-sectional and descriptive studies. For meta-analysis Mantel-Haenszel Odds Ratio (M.H. O.R.) with its 95% Confidence Interval (C.I), Mean Difference (M.D) with its 95 % C.I were computed. The Review Manager Software (Rev Man 5, Cochrane collabouration, Oxford, England) was used for data analytics. Results: Overall, 115 citations were identified from the initial search, of which 29 studies were retrieved. Later, 14 studies were excluded. Of the remaining 15 studies, 12 were subjected to meta-analysis. There was a change in Left Ventricular (LV) end diastolic diameter (M.D=2.0; p<0.001; 95% C.I=1.13 to 2.86), and cardiac index (M.D=0.63; p<0.001, 95% C.I=0.46 to 0.79) from baseline to atleast three months of postsurgery among HOHF-AVF patients. According to the AVF flow, there was a change in LV systolic diameter (M.D=-18.90; p<0.01; 95% C.I=-22.84 to-14.96), cardiac index (M.D=0.50; p=0.007; 95% C.I=0.14 to 0.86) and tricuspid annular plane systolic excursion (M.D=3.90; p=0.03; 95% C.I=0.30 to 7.50). Conclusion: Left ventricular end diastolic diameter and cardiac index were found to be the major determinants for a HOHFAVF. The left ventricular mass index, ejection fraction, posterior wall thickness, interventricular septum were not associated with HOHF-AVF. Left ventricular systolic diameter, cardiac index and tricuspid annular plane systolic excursion were the determinants of AVF flow.