Intraluminal guidance system using bioelectric impedance

Abstract

A system using bioelectric impedance to guide a flexible elongate transluminal device through an occlusion in a vessel. The device can be a guidewire or a device for performing an atherectomy, discectomy, ablation or similar technique. The device includes a first electrode disposed on a distal portion of the device. A second electrode is disposed in electric contact with the patient separate from the first electrode. An electric current is supplied between the first and second electrodes and a voltage drop is measured between the first and second electrodes. The voltage drop is converted to bioelectric impedance. Based on the impedance measurement, a clinician can determine if the device is approaching the vessel wall, permitting the clinician to redirect the device away from the vessel wall.

Description

FIELD OF THE INVENTION [0001] The disclosure relates generally to a guidance system for use in a patient's vessel, and more particularly, to a system for guiding an intra-luminal device through an arterial chronic total occlusion (CTO) using bioelectric impedance. BACKGROUND OF THE INVENTION [0002] Stenotic lesions may comprise a hard, calcified substance and / or a softer thrombus material, each of which forms on the lumen walls of a blood vessel and restricts blood flow there through. Intra-luminal treatments, such as balloon angioplasty, stent deployment, atherectomy, and thrombectomy are well known and have proven effective in the treatment of such stenotic lesions. These treatments often involve the insertion of a therapy catheter into a patient's vasculature, which may be torturous and may have numerous stenoses of varying degrees throughout its length. In order to place the distal, treatment portion of a catheter within the treatment site, a steerable guidewire is typically int...

AI Technical Summary

Benefits of technology

[0010] During use of the above system to guide an elongate device through a vessel occlusion in a patient, a first electrode is disposed adjacent the occlusion targeted for crossing. A second electrode is spaced apart from the first electrode and disposed in electrical contact with the patient's tissue, e.g., against the wall of the occluded or another vessel. The second electrode may be a skin electrode in contact with the patient's skin. As the elongate device is advanced through the occlusion, an electric current is supplied between the first and second electrodes and a voltage drop is measured between the first and second electrodes. The voltage drop is converted arithmetically to a calculated bioelectric impedance. By comparing the measured / calculated bioelectric impedance to a known, e.g., expected standard or previously measured impedance, a clinician can determine whether the device is approaching the vessel wall and posing a risk of perforating the wall. With this information, the clinician can halt advancement of the device, and possibly redirect the device away from the vessel wall.

Problems solved by technology

These treatments often involve the insertion of a therapy catheter into a patient's vasculature, which may be torturous and may have numerous stenoses of varying degrees throughout its length.

In some instances, the extent of occlusion of the lumen is so severe that the lumen is completely or nearly completely obstructed, leaving virtually no passageway for the guidewire.

This fibrous cap may present a surface that is difficult to penetrate with a conventional guidewire, and the typically flexible distal tip of the guidewire may be unable to cross the lesion.

However, blood vessels are not straight and fluoroscopic visualization of the natural path through an occlusion is poor because there is little or no flow of radiographic contrast through the occlusion.

Therefore, simply using a stiffer guidewire to push through an occlusion increases the risk that the guidewire tip will penetrate the vessel wall.

Atherectomy devices also present the danger of unwanted perforation of a vessel wall by the material removal device.

This can occur when the material removal device improperly engages the vessel wall, for example when the material removal device is not oriented substantially parallel to the axis of the vessel.

In this situation, the material removal device, e.g. cutter or abrasive ablator, may improperly engage the vessel wall and cause unwanted damage thereto.

Other ablation and discectomy devices also present the danger of damage to a vessel wall.

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