Devices and methods for delivering fluid to tissue during ablation therapy

Inventors

Curley, Michael G. • Eberl, Gregory R. • Clevenger, Jason M. • Howard, Michael T. • Delly, Erik

Assignees

Thermedical Inc

Abstract

Devices and methods for delivering fluid to tissue during ablation therapy are described herein. An exemplary device can include an elongate body having an inner lumen, outlet ports, and an ablation element configured to heat tissue. A flow resistance of the elongate body can increase along a length of the elongate body containing the outlet ports in a proximal to distal direction. This can be accomplished by, for example, varying outlet port size or relative spacing, decreasing a cross-sectional area of the inner lumen through which fluid can flow using a flow diverter or tapered inner lumen sidewalls, or limiting a ratio between a total area of the outlet ports and a cross-sectional area of the inner lumen. Adjusting flow resistance of the elongate body can provide more uniform fluid distribution or a desired non-uniform distribution.

Core Innovation

The disclosure relates to devices and methods for delivering fluid to tissue during ablation therapy. An elongate body is inserted into a tissue mass with a tissue-penetrating distal tip, where the elongate body includes an inner lumen and a fluid delivery portion with a plurality of outlet ports. Fluid is delivered from the inner lumen through the fluid delivery portion into the tissue mass, while ablative energy is delivered to the tissue mass from an ablation element located on the elongate body.

A key aspect of the invention is regulating fluid distribution by counterintuitively increasing flow resistance along the length containing the outlet ports. Less than about 70% by volume of fluid delivered to the tissue mass is emitted from outlet ports disposed in a distal 25% of the fluid delivery portion, and the disclosure further includes quantitative constraints on fluid emitted from different longitudinal regions of the fluid delivery portion to obtain a desired non-uniform or more controlled distribution rather than a distally-biased distribution.

The disclosure also addresses current density edge heating by relating outlet port placement to ablation element boundaries and by introducing flow resistance features such as a flow diverter and tapered inner lumen sidewalls. The text reports experiments comparing original outlet-port geometries to modified outlet-port patterns and to configurations with a cone-shaped flow diverter, including measurements of larger lesion volumes and reduced therapy impedance and non-recovering impedance rise for the improved configurations.

Claims Coverage

The document provides one independent claim, directed to a method of delivering fluid to tissue using an elongate body with an inner lumen, a fluid delivery portion with multiple outlet ports, and an ablation element, together with a quantitative limitation on how much delivered fluid is emitted from outlet ports in a distal portion. Dependent claims further narrow the method with additional quantitative emission constraints, optional fluid heating, substantially uniform flow, and fluid delivery positioned immediately adjacent to a boundary of the ablation element.

Across the claims, the central inventive structure is a fluid delivery portion with multiple outlet ports on an elongate body delivering fluid through an inner lumen during ablation, combined with quantitative regional limits on the volume of emitted fluid from distal or proximal portions. Further inventive coverage includes optional heating within the inner lumen, substantially uniform flow from the outlet ports, and delivering fluid immediately adjacent to a boundary of the ablation element.

Stated Advantages

Documented Applications