Described in one aspect is a multi-pressure monitoring system for cell or other therapy includes a first catheter having a first lumen for accepting a treatment device, a second lumen for inflating a balloon, a pressure sensor for monitoring fluid pressure within the first lumen, and a flow restrictor such as a hemostasis valve for limiting the exchange of fluids into and out of the first lumen while treatment devices are present or exchanged in the first lumen. Also disclosed is a method of using the first catheter with a first pressure monitor coupled to the first pressure sensor along with a second catheter attached to a second pressure sensor coupled to a second pressure monitor. The second catheter is positioned within the first lumen of the first catheter during treatment operations and the first and second pressure monitors are used to verify proper pressures throughout the procedure. Described also are novel methods, systems, and catheters for delivering flowable therapeutic substances, such as viable cellular preparations, to patients.