Coaxial catheter instruments for ablation with radiant energy

Abstract

Ablation methods and instruments are disclosed for creating lesions in tissue, especially cardiac tissue for treatment of arrhythmias and the like. Percutaneous ablation instruments in the form of coaxial catheter bodies are disclosed having at least one central lumen therein and having one or more balloon structures at the distal end region of the instrument. The instruments include an energy emitting element which is independently positionable within the lumen of the instrument and adapted to project radiant energy through a transmissive region of a projection balloon to a target tissue site. The instrument can optionally include at least one expandable anchor balloon disposed about, or incorporated into an inner catheter body designed to be slid over a guidewire. This anchor balloon can serve to position the device within a lumen, such as a pulmonary vein. A projection balloon structure is also disclosed that can be slid over the first (anchor balloon) catheter body and inflated within the heart, to define a staging from which to project radiant energy. An ablative fluid can also be employed outside of the instrument (e.g., between the balloon and the target region) to ensure efficient transmission of the radiant energy when the instrument is deployed. In another aspect of the invention, generally applicable to a wide range of cardiac ablation instruments, mechanisms are disclosed for determining whether the instrument has been properly seated within the heart, e.g., whether the device is in contact with a pulmonary vein and/or the atrial surface, in order to form a lesion by heating, cooling or projecting energy. This contact-sensing feature can be implemented by an illumination source situated within the instrument and an optical detector that monitors the level of reflected light. Measurements of the reflected light (or wavelengths of the reflected light) can thus be used to determine whether contact has been achieved and whether such contact is continuous over a desired ablation path.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application is a continuation-in part of U.S. patent application Ser. No. 09 / 924,393, filed on Aug. 7, 2001, which is a continuation-in-part of U.S. patent application Ser. No. 09 / 390,964, filed Sep. 7, 1999, now U.S. Pat. No. 6,270,492 issued Aug. 7, 2001, which is a continuation-in-part of U.S. patent application Ser. No. 08 / 991,130, filed Dec. 16, 1997, now U.S. Pat. No. 5,947,595 issued Sep. 7, 1999, which is a continuation-in-part of U.S. patent application Ser. No. 08 / 827,631, filed Apr. 10, 1997, now U.S. Pat. No. 5,908,415 issued Jun. 1, 1999, which is a continuation of U.S. patent application Ser. No. 08 / 303,605, filed Sep. 9, 1994, abandoned. [0002] This application is also a continuation-in-part of U.S. patent application Ser. No. 09 / 616,275 filed Jul. 14, 2000, which is a continuation-in-part of U.S. patent application Ser. No. 09 / 602,420 filed Jun. 23, 2000, which is a continuation-in-part of U.S. patent application Se...

AI Technical Summary

Benefits of technology

[0024] In a further aspect of the invention, percutaneous instruments are disclosed that can achieve rapid and effective photoablation through the use of tissue-penetrating radiant energy. It has been discovered that radiant energy, e.g., projected electromagnetic radiation or ultrasound, can create lesions in less time and with less risk of the adverse types of surface tissue destruction commonly associated with prior art approaches. Unlike instruments that rely on thermal conduction or resistive heating, controlled penetrating radiant energy can be used to simultaneously deposit energy throughout the full thickness of a target tissue, such as a heart

Problems solved by technology

The regular pumping function of the atria is replaced by a disorganized, ineffective quivering as a result of chaotic conduction of electrical signals through the upper chambers of the heart.

Devices that rely upon resistive or conductive heat transfer can be prone to serious post-operative complications.

To achieve this, the temperature at the contact surface will typically be raised to greater than 100° C. In this temperature regime, there is a substantial risk of tissue destruction (e.g., due to water vaporization micro-explosions or due to carbonization).

Charring of the surface of the heart tissue, in particular, can lead to the creation of blood clots on the surface and post-operative complications, including stroke.

When the light energy is delivered in the form of a focused spot, the process is inherently time consuming because of the need to expose numerous spots to form a continuous linear or curved lesion.

In addition, existing instruments for cardiac ablation also suffer from a variety of design limitations.

The shape of the heart muscle adds to the difficulty in accessing cardiac structures, such as the pulmonary veins on the anterior surface of the heart.

Moreover, because the lesion is formed by an ablation element carried on the surface of the balloon element, the balloon shape inherent

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