Blood flow restrictors are discussed. In some examples, a blood flow restrictor apparatus is configured to be placed within a destination vessel for an arteriovenous hemodialysis access. In an example, the apparatus includes a tubular portion including a delivery configuration and a deployed configuration. In a further example, a size-limiting portion is configured to constrain a size of the tubular portion in the deployed configuration. The tubular portion, in some examples, includes a first portion including a first size substantially matching an interior size of the destination vessel with the tubular portion in the deployed configuration. In another example, the tubular portion includes a second portion constrained by the size-limiting portion to include a second size smaller than the first size of the tubular portion.