Disclosed herein are catheter assemblies and methods thereof that address various aspects of at least the retrograde tunneling technique. The catheter assemblies include, but are not limited to, catheter assemblies configured for vascular access, catheter assemblies configured for priming, catheter assemblies configured for tunneling, and mechanisms for connecting catheter tubes to their respective catheter assemblies. The methods include, but are not limited to, priming, tunneling, and connecting catheter tubes to their respective catheter assemblies.