A system comprising a dual lumen catheter (80, 90); the dual lumen catheter comprising: a tip (89, 99); a first lumen (82, 92) having a proximal end and a distal end; a second lumen (84, 94) having a proximal end and a distal end; an exit port proximal to a distal end of the catheter; a mixing chamber (87, 97) at the tip of the catheter; the system further comprising: a first low viscosity fluid, wherein the catheter (80, 90) is configured to receive the first low viscosity fluid at the proximal end of the first lumen (82, 92), a second low viscosity fluid, wherein the catheter is configured receive the second low viscosity fluid at the proximal end of the second lumen (84, 94); wherein the catheter is configured to mix the first low viscosity fluid and the second low viscosity fluid to form a high viscosity fluid in the mixing chamber; the system characterised in that the dual lumen catheter comprises: a heat source arranged to heat the first low viscosity fluid and the second low viscosity fluid separately for lowering the viscosity of the separate fluids, and further to heat said high viscosity fluid to speed up the reaction of the first and second low viscosity fluids. a dual lumen catheter (80, 90); the dual lumen catheter comprising: a tip (89, 99); a first lumen (82, 92) having a proximal end and a distal end; a second lumen (84, 94) having a proximal end and a distal end; an exit port proximal to a distal end of the catheter; a mixing chamber (87, 97) at the tip of the catheter; the system further comprising: a first low viscosity fluid, wherein the catheter (80, 90) is configured to receive the first low viscosity fluid at the proximal end of the first lumen (82, 92), a second low viscosity fluid, wherein the catheter is configured receive the second low viscosity fluid at the proximal end of the second lumen (84, 94); wherein the catheter is configured to mix the first low viscosity fluid and the second low viscosity fluid to form a high viscosity fluid in the mixing chamber; the system characterised in that the dual lumen catheter comprises: a heat source arranged to heat the first low viscosity fluid and the second low viscosity fluid separately for lowering the viscosity of the separate fluids, and further to heat said high viscosity fluid to speed up the reaction of the first and second low viscosity fluids. a tip (89, 99); a first lumen (82, 92) having a proximal end and a distal end; a second lumen (84, 94) having a proximal end and a distal end; an exit port proximal to a distal end of the catheter; a mixing chamber (87, 97) at the tip of the catheter; the system further comprising: a first low viscosity fluid, wherein the catheter (80, 90) is configured to receive the first low viscosity fluid at the proximal end of the first lumen (82, 92), a second low viscosity fluid, wherein the catheter is configured receive the second low viscosity fluid at the proximal end of the second lumen (84, 94); wherein the catheter is configured to mix the first low viscosity fluid and the second low viscosity fluid to form a high viscosity fluid in the mixing chamber; the system characterised in that the dual lumen catheter comprises: a heat source arranged to heat the first low viscosity fluid and the second low viscosity fluid separately for lowering the viscosity of the separate fluids, and further to heat said high viscosity fluid to speed up the reaction of the first and second low viscosity fluids. a first low viscosity fluid, wherein the catheter (80, 90) is configured to receive the first low viscosity fluid at the proximal end of the first lumen (82, 92), a second low viscosity fluid, wherein the catheter is configured receive the second low viscosity fluid at the proximal end of the second lumen (84, 94); wherein the catheter is configured to mix the first low viscosity fluid and the second low viscosity fluid to form a high viscosity fluid in the mixing chamber; the system characterised in that the dual lumen catheter comprises: a heat source arranged to heat the first low viscosity fluid and the second low viscosity fluid separately for lowering the viscosity of the separate fluids, and further to heat said high viscosity fluid to speed up the reaction of the first and second low viscosity fluids.