A pressure isolation mechanism for use in a medical procedure includes a lumen, an isolation port in fluid connection with the lumen, and a valve having a first state and a second state. The first state occurs when the lumen and the isolation port are connected. The second state occurs when the lumen and the isolation port are disconnected. The lumen remains open for flow of fluid therethrough in the first state and in the second state. The valve is preferably spring-biased in the first state and is switchable to the second state when fluid pressure in the lumen reaches a predetermined pressure level. Alternately, an actuator can control the state of the valve. A pressure transducer can be in fluid connection with the isolation port of the pressure isolation mechanism. A fluid delivery system includes a syringe and a pressure isolation mechanism as described above.