A system of devices for introducing an interventional device into a carotid artery, the system comprising: an arterial access sheath adapted to introduce an interventional device into an artery, the arterial access sheath including a sheath body sized and shaped to be introduced into a common carotid artery via a carotid artery access site, the sheath body defining an internal lumen that provides a passageway for introducing an interventional device into the common carotid artery when the sheath body is positioned in the common carotid artery, the arterial access sheath further including a connector that forms a y-arm , wherein the y-arm connects to a flow line defining an internal lumen that is fluidly connected to the internal lumen of the sheath body ; an elongated first dilator positionable within the internal lumen of the sheath body, the first dilator having a tapered distal tip sized and shaped to dilate a needle puncture site to a larger diameter for insertion of the arterial access sheath into the artery, the first dilator having an internal lumen to allow the dilator to be inserted over a sheath guidewire into an artery, wherein at least a portion of the first dilator has a first bending stiffness, wherein the arterial access sheath and the first dilator can be collectively introduced into the common carotid artery; characterized in that the system further comprises a sheath stopper slideably mounted over the outside of the distal portion of the sheath body for creating a positive stop for contacting an artery wall, wherein a distal end of the sheath stopper forms an angled flange for contacting the arterial wall, wherein a proximal portion of the sheath stopper has a locking feature that engages with a corresponding locking feature on the connector . an arterial access sheath adapted to introduce an interventional device into an artery, the arterial access sheath including a sheath body sized and shaped to be introduced into a common carotid artery via a carotid artery access site, the sheath body defining an internal lumen that provides a passageway for introducing an interventional device into the common carotid artery when the sheath body is positioned in the common carotid artery, the arterial access sheath further including a connector that forms a y-arm , wherein the y-arm connects to a flow line defining an internal lumen that is fluidly connected to the internal lumen of the sheath body ; an elongated first dilator positionable within the internal lumen of the sheath body, the first dilator having a tapered distal tip sized and shaped to dilate a needle puncture site to a larger diameter for insertion of the arterial access sheath into the artery, the first dilator having an internal lumen to allow the dilator to be inserted over a sheath guidewire into an artery, wherein at least a portion of the first dilator has a first bending stiffness, wherein the arterial access sheath and the first dilator can be collectively introduced into the common carotid artery; characterized in that the system further comprises a sheath stopper slideably mounted over the outside of the distal portion of the sheath body for creating a positive stop for contacting an artery wall, wherein a distal end of the sheath stopper forms an angled flange for contacting the arterial wall, wherein a proximal portion of the sheath stopper has a locking feature that engages with a corresponding locking feature on the connector . <EOS>