Methods and systems for establishing retrograde carotid arterial blood flow
Interventional procedures on the carotid arteries are performed through a transcervical access while retrograde blood flow is established from the internal carotid artery to a venous or external location. A system for use in accessing and treating a carotid artery includes an arterial access device, a shunt fluidly connected to the arterial access device, and a flow control assembly coupled to the shunt and adapted to regulate blood flow through the shunt between at least a first blood flow state and at least a second blood flow state. The flow control assembly includes one or more components that interact with the blood flow through the shunt.
1. A method for accessing and treating a carotid artery, comprising:
forming a transcervical incision in a neck of a patient;
forming a penetration in a wall of a common carotid artery via the transcervical incision, the penetration being located at distance of around 5 cm to 7 cm below a bifurcation location where the patient's common carotid artery bifurcates into an internal carotid artery and external carotid artery;
positioning an arterial access sheath through the transcervical incision and the penetration, wherein the arterial access sheath has a working length of 5 cm to 15 cm;
inserting no more than the working length of the arterial access sheath into the common carotid artery;
blocking blood flow from the common carotid artery past the sheath;
allowing retrograde blood flow from the internal carotid artery into the sheath and into a shunt from the sheath while the common carotid artery remains blocked; and
adjusting the state of retrograde blood flow through the shunt.
2. A method as in claim 1 , wherein adjusting the state of retrograde blood flow comprises changing from a passive flow state to an active flow state.
3. A method as in claim 1 , wherein adjusting the state of retrograde blood flow comprises changing the flow rate from a passive low flow state to a passive high flow state.
4. A method as in claim 3 , wherein the rate is controlled over a range from a low rate to a high rate, where the high rate is at least three fold higher than the low rate.
5. A method as in claim 3 , wherein the high rate is at least three fold higher than the low rate.
6. A method as in claim 3 , wherein the high rate is at least five fold higher than the low rate.
7. A method as in claim 1 , wherein adjusting the state of retrograde blood flow comprises changing the flow rate from a passive low flow state to an active high flow state.
8. A method as in claim 1 , wherein adjusting the state of retrograde blood flow comprises changing the flow rate from a passive low flow state to a state where blood flow through the shunt is aspirated.
9. A method as in claim 1 , wherein adjusting comprises adjusting flow resistance from the arterial access sheath to a return site, wherein the flow resistance within the shunt is adjusted using a flow control element attached directly to the shunt.
10. A method as in claim 9 , wherein the resistance is adjusted causing blood to flow through a flow resistance element coupled to the shunt.
11. A method as in claim 1 , wherein adjusting comprises actively pumping blood from the arterial access sheath to a venous return site.
12. A method as in claim 1 , wherein retrograde flow is controlled at a baseline low flow rate in the range from 10 ml/min to 200 ml/min during a majority of a procedure.
13. A method as in claim 1 , wherein the retrograde flow is increased to a higher rate when there is an increased risk of emboli release.
14. A method as in claim 1 , wherein the procedure comprises stenting of the internal carotid artery and the flow rate is increased during at least one of when a stent delivery catheter is introduced to the carotid artery, when the stent is deployed in the carotid artery, when the stent delivery catheter is removed from the carotid artery, or when the common carotid artery occlusion is released.
15. A method as in claim 1 , wherein the flow rate is increased manually by the user.
16. A method as in claim 1 , wherein the flow rate is increased automatically.
17. A method as in claim 1 , further comprising measuring the retrograde flow rate, wherein the continuous retrograde flow rate is controlled based on the measured flow rate.
18. A method as in claim 1 , wherein the rate of retrograde flow is cycled between a lower flow rate and a higher flow rate to dislodge emboli from the common and external carotid arteries.
19. A method for accessing and treating a carotid artery, comprising:
forming a penetration in a wall of a common carotid artery;
positioning an arterial access sheath through the penetration;
blocking blood flow from the common carotid artery past the sheath;
allowing retrograde blood flow from the internal carotid artery into the sheath and into a shunt from the sheath while the common carotid artery remains blocked; and
adjusting the state of retrograde blood flow through the shunt, wherein adjusting comprises adjusting flow resistance from the arterial access sheath to a return site by causing blood to flow through a flow resistance element coupled to the shunt, wherein the flow resistance element comprises two or more parallel flow paths of the shunt and a valve to open or close one or more of the flow paths to selectively direct blood flow through one or more of the flow paths.
20. A method as in claim 19 , wherein the parallel flow paths include a main flow path and a secondary flow path, and wherein the secondary flow path has a higher resistance to blood flow than the main flow path.
21. A method as in claim 20 , wherein the secondary flow path is longer than the main flow path.
22. A method as in claim 20 , wherein the secondary flow path has a smaller diameter than the main flow path.
23. A method as in claim 20 , wherein the valve is configured to block blood flow through the main flow path of the shunt such that blood flow through the shunt is diverted entirely to the secondary flow path thereby increasing the flow resistance and reducing the blood flow rate through the shunt.
24. A method as in claim 19 , further comprising a controller that can be actuated by a user to control the valve.
25. A method as in claim 24 , wherein the flow resistance element and the controller are integrated into a single housing.
26. A method as in claim 19 , wherein retrograde flow is controlled at a baseline low flow rate in the range from 10 ml/min to 200 ml/min during a majority of a procedure.
27. A method as in claim 19 , wherein the retrograde flow is increased to a higher rate when there is an increased risk of emboli release.
28. A method as in claim 19 , wherein the procedure comprises stenting of the internal carotid artery and the flow rate is increased during at least one of when a stent delivery catheter is introduced to the carotid artery, when the stent is deployed in the carotid artery, when the stent delivery catheter is removed from the carotid artery, or when the common carotid artery occlusion is released.
29. A method as in claim 19 , wherein the flow rate is increased manually by the user.
30. A method as in claim 19 , wherein the flow rate is increased automatically.
31. A method as in claim 19 , further comprising measuring the retrograde flow rate, wherein the continuous retrograde flow rate is controlled based on the measured flow rate.
32. A method as in claim 19 , wherein the rate of retrograde flow is cycled between a lower flow rate and a higher flow rate to dislodge emboli from the common and external carotid arteries.
33. A method for accessing and treating a carotid artery, comprising:
forming a transcervical incision in a neck of a patient;
forming a penetration in a wall of a common carotid artery;
inserting a distal section of the arterial access sheath through the transcervical incision and the penetration, wherein the arterial access sheath includes a removable stopper member that covers a portion of the distal section of the sheath such that a portion of the distal section of the sheath is covered by the stopper member and a portion of the distal section of the sheath is exposed, wherein the stopper member, when coupled to the sheath, limits insertion of the sheath into the carotid artery to the exposed portion;
inserting no more than the exposed portion of the sheath into the common carotid artery;
blocking blood flow from the common carotid artery past the sheath;
allowing retrograde blood flow from the internal carotid artery into the sheath and into a shunt from the sheath while the common carotid artery remains blocked; and
adjusting the state of retrograde blood flow through the shunt using a flow control element attached directly to the shunt.