Devices, systems, and methods for closing the base of a left atrial appendage or other tissue structure comprise a device applicator having jaws, a shaft, and a handle. First and second triggers on a handle are configured to close the jaws and a closure device in a step-wise manner where tissue penetrating fasteners within the closure device are engaged by studs on the jaws, where the studs must be released prior to the opening of the jaws.
