Thread by @aishaikh

💥’Dialysis AV Fistula & the Heart:
Friend or Foe?’ - Tweetorial

⚡️Let’s review the following:
☄️Hemodynamic effects of an AVF
☄️Impact of AVF on Cardiac Structure
& Function
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@ASDINNews
@RenalFellowNtwk
#VascularAccessPearls

💥Why is it important to understand the impact of AVF on the heart?
⚡️Because AVF use has ⬆️ in 🇺🇸
⚡️Cardiac disease is highly prevalent among ESRD pts.
⚡️50% of all ESRD deaths are due to
a CV-related cause👇🏽
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💥What causes cardiac disease in ESRD patients?
⚡️Many factors contribute to it - as shown below👇🏽
⚡️In this tweetorial, the focus will be on how the AVF affects the heart
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💥What is an AVF?
⚡️It is a connection b/w an artery & a vein👇🏽
⚡️Blood gets diverted from the ‘High-resistance’ capillary bed to ‘Low-resistance’ venous system
⚡️This is why the Systemic Vascular Resistance (SVR) ⬇️ post-AVF creation
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💥Dialysis AVF was first described by Brescia & Cimino in 1966👇🏽
⚡️In 1972, two cases of heart failure were reported in dialysis pts. - both pts. had an AVF, & in both cases the symptoms of ❤️ failure improved w/ AVF flow reduction👇🏽
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💥What are the hemodynamic effects of an AVF?

AVF creation -> ⬇️SVR -> ⬇️BP ->
⬆️ Venous return to the ❤️ ->
⬆️LVEDV -> ⬆️ Cardiac Output

⚡️This was demonstrated in a study of Pre-dialysis CKD pts. who had echocardiograms pre & post AVF creation👇🏽
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💥Hemodynamic effects of AVF can be reversed with temporary manual occlusion of the AVF
⚡️As shown in this study👇🏽
☄️AVF occlusion -> ⬆️BP -> ⬇️ Heart rate -> ⬇️ SNS activity -> ⬇️ Cardiac Output
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💥Bradycardia induced by manual occlusion of the AVF is called the ‘Nicoladoni-Branham’ Sign
⚡️This Sign was described by these two MDs in the 19th century👇🏽
⚡️Why does bradycardia occur upon AVF occlusion?👇🏽
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💥Effect of AVF on Cardiac Structure & Function
⚡️This study of pre-dialysis CKD pts. showed worsening of Left Ventricular Hypertrophy (LVH) within 3 months post-AVF creation -> likely due to ⬆️ Cardiac Output -> due to ⬆️ AVF flow & ⬆️ Venous return
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💥Another study demonstrated ⬆️ in LVH after AV Access creation, BUT in this study the AVF flow rate did NOT correlate with ⬆️ in LV Mass Index - Why?
⚡️This could have been because the average AV access flow rate in this cohort was low at 975 ml’s/min
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💥Why should one care about LVH in CKD pts?
⚡️Because LVH is highly prevalent in CKD pts. & it is associated w/ ischemic heart disease, heart failure & death
⚡️Progression of LVH in ESRD pts. is associated with ⬇️ survival👇🏽
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💥If LVH is bad for CKD pts, then do interventions that cause ⬇️ in LVH improve outcomes?
⚡️This meta-analysis did NOT show correlation b/w intervention-induced LVH regression & ⬇️ in mortality
⚡️Note: AVF ligation was NOT an intervention in this study👇🏽
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💥AVF can cause LVH, but does it also affect the Right Ventricle?
⚡️Yes - this retrospective study showed ⬆️ RV dilatation & RV dysfunction post-AVF creation
⚡️RV changes were associated with ⬆️ mortality👇🏽
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💥Can AVF cause Heart Failure?
⚡️Yes - Classic description of ❤️ failure seen with AVF is ‘High-output Failure’ due to ⬆️Cardiac Output👇🏽
⚡️But ❤️ failure due to an AVF can also occur w/ Low Cardiac Output if the pt. has poor myocardial reserve
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💥Does the AVF flow rate correlate with high Cardiac Output?
⚡️Yes
⚡️Relationship b/w AVF flow rate & Cardiac Output is NOT linear👇🏽
⚡️Cardiac Output sharply ⬆️ when AVF flow rate is >2 L/min.👇🏽
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💥Is high Cardiac Output (resulting from high-flow AVF) associated w/ ⬆️ risk of heart failure?
⚡️Yes
⚡️In this study, AVF flow rate of >2 L/min. & AVF flow/Cardiac Output ratio of >0.2 were associated with ⬆️ risk of High-output Heart Failure👇🏽
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💥High-output Heart Failure is treated with AVF flow reduction👇🏽
⚡️If AVF flow reduction is not possible or if flow reduction not improve symptoms of heart failure then AVF ligation is indicated
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💥Here is the summary of the Hemodynamic effects & the Cardiac effects of an AVF👇🏽
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💥AVF & the Heart: Friend or Foe?
⚡️It depends...👇🏽
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💥Summary:
⚡️AVF are associated with better CV outcomes compared to CVCs👇🏽
⚡️AVF-related cardiac complications are highly dependent on AVF flow rate👇🏽
⚡️AVF flow rate of >2 L/min. ⬆️ risk of ❤️ failure - Rx is AVF flow reduction or AVF ligation
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