A catheter, comprising: an inner tubular member having a length, an exterior surface and a fluid lumen defined therein, the exterior surface defining a first distal flow port in fluid communication with the fluid lumen and a second distal flow port in fluid communication with the fluid lumen； an outer tubular member movable relative to the inner tubular member in a proximal direction along a length of the inner tubular member, the outer tubular member having an interior surface directed toward the exterior surface of the inner tubular member； a first pressure chamber defined between the exterior surface of the inner tubular member and the interior surface of the outer tubular member, and between a first distal seal assembly and a first proximal seal assembly, the first pressure chamber in fluid communication with the first distal flow port； and a second pressure chamber defined between the exterior surface of the inner tubular member and the interior surface of the outer tubular member, and between a second distal seal assembly and a second proximal seal assembly, the second pressure chamber in fluid communication with the second distal flow port； wherein in a relative position of the outer tubular member and the inner tubular member, the first pressure chamber is in fluid communication with the first distal flow port and the second pressure chamber is in fluid communication with the second distal flow port, and when the outer tubular member moves a predetermined distance in the proximal direction, the first pressure chamber is in fluid communication with both the first distal flow port and second distal flow port.
