Telescoping Atherectomy Device with Self-Driving Screw Pump
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Solution Overview
Problem
Current atherectomy devices struggle to effectively cut and remove various types of plaque, including calcified, necrotic, soft, and fibrotic plaque, often leading to incomplete removal, emboli formation, and increased risk of restenosis, especially in tight or tough lesions with limited luminal opening.
Innovation Solution
The development of telescoping, self-driving, or lateral pushing atherectomy devices with a flexible sheath and cutter assembly, featuring a helical flute design and positive displacement pump, which allows for concentric vessel lumen creation, safe emboli collection, and reduced vessel injury, capable of handling tight lesions with minimal luminal opening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional balloon dilatation and stent placement are used, then the artery can be opened to maintain lumen integrity, but the artery is stretched and scar tissue formation is induced leading to restenosis
Solution Approach 1:
The atherectomy device extracts and removes plaque material from the arterial wall before stent placement, thereby reducing the amount of arterial stretching required and minimizing scar tissue formation. The cutter assembly physically removes the harmful plaque burden that would otherwise require aggressive dilation.
Solution Approach 2:
The atherectomy procedure is performed as a preliminary action before balloon dilatation and stent placement. By removing plaque beforehand, the subsequent dilation requires less force and causes less arterial injury, thereby reducing restenosis risk.
2Ease of operation
If atherectomy devices with rotating cutters are used, then plaque can be cut from the vessel wall, but the devices cannot effectively handle all types of plaque (soft, fibrous, calcific) and may break plaque into large emboli pieces
Solution Approach 1:
The cutter assembly incorporates a composite structure with a compliant carrier and a harder cutting element. This composite design allows the cutter to effectively cut through various plaque types (soft, fibrous, calcific) while the compliant carrier absorbs shocks and prevents plaque from breaking into large embolic fragments.
Solution Approach 2:
The cutting parameters are optimized by using a cutter with specific hardness and geometry that can adapt to different plaque compositions. The cutting depth, speed, and pressure are controlled to minimize plaque fragmentation into dangerous emboli sizes.
3Productivity
If sharp cutters with deflection are used to perform eccentric cutting, then cutting effectiveness is improved, but the amount of deflection cannot be effectively controlled
Solution Approach 1:
The device incorporates feedback mechanisms that allow the operator to control the degree of cutter deflection. Sensors or mechanical feedback systems provide real-time information about cutting forces, enabling precise control of eccentric cutting depth and angle to optimize plaque removal while avoiding vessel wall injury.
4Productivity
If tight or tough lesions with very small luminal opening are treated, then plaque removal is needed to create passage, but guidewire and device passage through the lesion is difficult or impossible
Solution Approach 1:
The atherectomy device is designed with a nested structure where the cutter assembly can be contained within a delivery catheter that passes through the tight lesion first. The cutter is deployed only after the delivery system has successfully navigated the occlusion, enabling treatment of total occlusions and tight lesions that would otherwise be inaccessible.
Data Source
AI summary
Telescoping, self-driving, and laterally-pushing atherectomy devices are provided, each having a flexible sheath, a cutter with helical flutes, and a drive assembly. The drive assembly can have a flexible driveshaft that is rotatably translational within the lumen of the flexible sheath, a positive displacement pump that begins pumping at the distal end of the drive shaft adjacent to the helical flutes at the proximal end of the cutter, and the flexible drive shaft can be longer than the flexible sheath to enable a reversible telescoping of the drive assembly from the lumen of the flexible sheath. The positive displacement pump can be a screw pump having a drive screw portion extending beyond the flexible sheath, exposed for contact with a vascular lumen for the self-driving. And, the devices can have a reversibly-expandable, lateral pushing member at the distal end of the flexible sheath for the lateral pushing.