Aspiration thrombectomy system and methods for thrombus removal with aspiration catheter
A clot removal system comprises a catheter, a vacuum source, and a controller. The catheter comprises a proximal end, a distal end, and controller operating parameters and defines a lumen configured to be filled with a liquid column having a proximal portion. The vacuum source is configured to supply vacuum. The controller is configured to carry out a control pattern of turning on and off the vacuum based upon the controller operating parameters and is configured to receive the controller operating parameters in an automatic response to the catheter being operatively connected to at least one of the vacuum source and the controller and, responsive to the connection, to carry out the control pattern to change a level of vacuum at the distal end of the catheter.
1. An aspiration thrombectomy system, comprising:
an aspiration catheter having a proximal portion, a distal end and a lumen extending through the catheter;
a vacuum source fluidically coupled to the catheter;
a vacuum valve connected between the vacuum source and the proximal portion of the catheter to control a vacuum flow in the catheter lumen;
a vent valve fluidically coupled to the proximal portion of the catheter, the vent valve being configured to control a flow of a vent fluid in the catheter lumen; and
a controller configured to open and close the vacuum valve and the vent valve in a predetermined cycle to change a level of vacuum at the distal end of the catheter and to control fluid flow in and out from the distal end of the catheter.
2. The system of claim 1 , further comprising a vent fluid source, and wherein:
the vent fluid source is configured to provide vent fluid at a pressure greater than atmospheric pressure; and
the controller is configured to cyclically open and close the vacuum valve and the vent valve to change a level of negative pressure and positive pressure at the distal end of the catheter during each cycle.
3. The system of claim 2 wherein the controller is configured to cyclically open and close the vacuum valve and the vent valve such that movement of the fluid column at the distal end of the catheter is limited to a positive amount of exit flow from approximately 0.001 ml to approximately 1.0 ml before fluid is drawn back into the catheter lumen.
4. The system of claim 2 wherein the controller is configured to cyclically open and close the vacuum valve and the vent valve such that movement of the fluid column at the distal end of the catheter is limited to a positive amount of exit flow of approximately 0.1 ml to approximately 0.5 ml before fluid is drawn back into the catheter lumen.
5. The system of claim 1 wherein the controller is configured to cyclically open and close the vacuum valve and the vent valve in a repeated cycle comprising an off-off state in which the vacuum valve is closed while the vent valve is closed.
6. The system of claim 1 wherein:
the controller is configured to cyclically open and close the vacuum valve and the vent valve in a cycle comprising (a) a first off-off state in which the vacuum valve is closed while the vent valve is closed, (b) a vacuum-only state following the first off-off state in which the vacuum valve is open while the vent valve is closed, (c) a second off-off state following the vacuum-only state in which the vacuum valve is closed while the vent valve is closed, and (d) a vent-only state following the second off-off state in which the vacuum valve is closed while the vent valve is open; and
the cycle is repeated.
7. The system of claim 6 wherein the cycle is repeated at a frequency of 2 Hz to 12 Hz.
8. The system of claim 1 wherein the vacuum valve and the vent valve are solenoid pinch valves.
9. The system of claim 1 wherein the vacuum valve and the vent valve are cammed pinch valves.
10. The system of claim 1 wherein the controller is configured to cyclically open and close the vacuum valve and the vent valve such that an amount of momentum transfer from the fluid column in the catheter lumen is sufficient to unstick thromboembolic material at the distal end of the catheter.
11. A method for removing thromboembolic material, comprising:
aspirating thromboembolic material from a person using the system of claim 1 by—
(a) positioning the distal end of the catheter at least proximate to thromboembolic material in a blood vessel of the person;
(b) applying a vacuum through the lumen of the catheter such that a vacuum flow draws at least a portion of the thromboembolic material into the catheter lumen; and
(c) controlling the vacuum valve fluidically coupled to the vacuum source and the catheter and the vent valve fluidically coupled to a vent fluid source and the catheter such that a level of vacuum at the distal end of the catheter changes and thereby controls flow in and out from the distal end of the catheter.
12. The method of claim 11 wherein:
the vent fluid source is configured to provide the vent fluid at a pressure greater than atmospheric pressure; and
controlling the vacuum valve and the vent valve comprises cyclically opening and closing the vacuum valve and the vent valve to change a level of negative pressure and positive pressure at the distal end of the catheter during each cycle.
13. The method of claim 12 wherein controlling the vacuum valve and the vent valve comprises limiting movement of a fluid column in the catheter lumen at the distal end of the catheter to a positive amount of exit flow within a range of a length of the fluid column that exits the distal end of the catheter.
14. The method of claim 13 wherein limiting movement of the fluid column at the distal end of the catheter comprises stopping a distal flow through the catheter lumen and reapplying the vacuum through the catheter lumen such that the positive amount of exit flow is approximately 0.5 mm to approximately 30 mm of the fluid column before fluid is drawn back into the catheter lumen.
15. The method of claim 12 wherein controlling the vacuum valve and the vent valve comprises limiting movement of a fluid column in the catheter lumen at the distal end of the catheter to a positive amount of exit flow within a range of volume of fluid that exits the distal end of the catheter.
16. The method of claim 15 wherein limiting movement of the fluid column at the distal end of the catheter comprises stopping a distal flow through the catheter lumen and reapplying the vacuum through the catheter lumen such that the positive amount of exit flow is approximately 0.001 ml to approximately 1.0 ml before fluid is drawn back into the catheter lumen.
17. The method of claim 15 wherein limiting movement of the fluid column at the distal end of the catheter comprises stopping a distal flow through the catheter lumen and reapplying the vacuum through the catheter lumen such that the positive amount of exit flow is approximately 0.1 ml to approximately 0.5 ml before fluid is drawn back into the catheter lumen.
18. The method of claim 11 , further comprising cyclically opening and closing the vacuum valve and the vent valve in a repeated cycle including an off-off state in which the vacuum valve is closed while the vent valve is closed.
19. The method of claim 11 , further comprising:
cyclically opening and closing the vacuum valve and the vent valve in a cycle including (a) a first off-off state in which the vacuum valve is closed while the vent valve is closed, (b) a vacuum-only state following the first off-off state in which the vacuum valve is open while the vent valve is closed, (c) a second off-off state following the vacuum-only state in which the vacuum valve is closed while the vent valve is closed, and (d) a vent-only state following the second off-off state in which the vacuum valve is closed while the vent valve is open; and
repeating the cycle.
20. The method of claim 19 wherein the cycle is repeated at a frequency of 2 Hz to 12 Hz.