A suction catheter system (100, 456) comprising: a guide catheter (102, 160, 458, 504, 714, 756) comprising a tubular shaft with a central lumen having, a proximal end and a distal opening, and a proximal section operably connected with the proximal end of the tubular shaft and having fittings that connect to a suction device, wherein the tubular shaft comprises an engagement section having an inner diameter associated with the lumen extending through the engagement section; and a suction extension (104, 230, 300, 460, 716, 752) comprising a connecting section (140, 234, 304, 400, 718, 760) with a central lumen, a tubular extension (142, 236, 306, 720, 736) comprising a tube that is connected with tubular element of the connecting section and extends from the connecting section in a distal direction, and a control structure comprising an elongated structure extending from the connecting section (140, 234, 304, 400, 718, 760) in a proximal direction, wherein at least a portion of the connecting section (140, 234, 304, 400, 718, 760) has a non-cylindrical cross section with a major outer diameter and a minor outer diameter smaller than the major outer diameter, the tubular extension having a distal inner diameter that is from about 20 percent to about 90 percent of the engagement section inner diameter, wherein the connecting section (140, 234, 304, 400, 718, 760) is configured to slide within the central lumen of the engagement section of the tubular shaft to change the relative position of the connecting section (140, 234, 304, 400, 718, 760) within the central lumen and provide for at least a portion of the narrow diameter suction extension to extend outward from the distal opening of the tubular shaft at appropriate configurations of the connecting section (140, 234, 304, 400, 718, 760), wherein a suction lumen is formed extending from the fitting configured to connect to the suction device through a portion of the central lumen, the connecting section (140, 234, 304, 400, 718, 760) and the tubular extension (142, 236, 306, 720, 736) to a distal opening of the tubular extension (142, 236, 306, 720, 736), and wherein the connecting section (140, 234, 304, 400, 718, 760) engages the inner lumen of the engagement section of the guide catheter at two locations along the circumference. a guide catheter (102, 160, 458, 504, 714, 756) comprising a tubular shaft with a central lumen having, a proximal end and a distal opening, and a proximal section operably connected with the proximal end of the tubular shaft and having fittings that connect to a suction device, wherein the tubular shaft comprises an engagement section having an inner diameter associated with the lumen extending through the engagement section; and a suction extension (104, 230, 300, 460, 716, 752) comprising a connecting section (140, 234, 304, 400, 718, 760) with a central lumen, a tubular extension (142, 236, 306, 720, 736) comprising a tube that is connected with tubular element of the connecting section and extends from the connecting section in a distal direction, and a control structure comprising an elongated structure extending from the connecting section (140, 234, 304, 400, 718, 760) in a proximal direction, wherein at least a portion of the connecting section (140, 234, 304, 400, 718, 760) has a non-cylindrical cross section with a major outer diameter and a minor outer diameter smaller than the major outer diameter, the tubular extension having a distal inner diameter that is from about 20 percent to about 90 percent of the engagement section inner diameter, wherein the connecting section (140, 234, 304, 400, 718, 760) is configured to slide within the central lumen of the engagement section of the tubular shaft to change the relative position of the connecting section (140, 234, 304, 400, 718, 760) within the central lumen and provide for at least a portion of the narrow diameter suction extension to extend outward from the distal opening of the tubular shaft at appropriate configurations of the connecting section (140, 234, 304, 400, 718, 760), wherein a suction lumen is formed extending from the fitting configured to connect to the suction device through a portion of the central lumen, the connecting section (140, 234, 304, 400, 718, 760) and the tubular extension (142, 236, 306, 720, 736) to a distal opening of the tubular extension (142, 236, 306, 720, 736), and wherein the connecting section (140, 234, 304, 400, 718, 760) engages the inner lumen of the engagement section of the guide catheter at two locations along the circumference.