The techniques of this disclosure generally relate to an assembly including a single branch stent device and a modular stent device configured to be coupled to the single branch stent device. The single branch stent device includes a main body and a branch coupling extending radially from the main body. The modular stent device includes a main body configured to be coupled inside of the main body of the single branch stent device, a bypass gate extending distally from a distal end of the main body of the modular stent device, and an artery leg extending distally from the distal end of the main body of the modular stent device.