Non-contact tissue ablation device and methods thereof

Abstract

A catheter for ablating body tissue of the interior regions of the heart includes a handle assembly, a shaft, and a distal tip section coupled to the distal end of the shaft. The distal tip section has a non-compliant and non-porous cap that has a tubular wall that defines a bore, and an ablation element that is housed inside the bore and spaced apart from the wall of the cap.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention is directed to systems and methods for mapping and ablating body tissue of the interior regions of the heart. More particularly, this invention relates to catheters and methods for ablating cardiac tissues using a deflectable catheter having an irrigated ablation element for the treatment of cardiac arrhythmia, for example atrial fibrillation and ventricular tachycardia.[0003]2. Description of the Prior Art[0004]Abnormal heart rhythms are generally referred to as cardiac arrhythmias, with an abnormally rapid rhythm being referred to as a tachycardia. The present invention is concerned with the treatment of tachycardias which are frequently caused by the presence of an “arrhythmogenic site” or “accessory atrioventricular pathway” close to the endocardial surface of the chambers of the heart. The heart includes a number of normal pathways which are responsible for the propagation of electrical signal...

AI Technical Summary

Benefits of technology

[0015]It is an objective of the present invention to provide a system and method that accurately positions a catheter at the desired treatment location.

[0016]It is another objective of the present invention to provide a system and method that provides improved ablation performance at the treatment location, especially in irregular endocardial surfaces.

Problems solved by technology

The presence of an arrhythmogenic site or an accessory pathway can bypass or short circuit the normal pathway, potentially resulting in very rapid heart contractions or tachycardias.

While drugs may be the treatment of choice for many patients, they only mask the symptoms and do not cure the underlying causes.

Implantable devices only correct the arrhythmia after it occurs.

Although successful, there are instances in which this technique may leave gaps between lesions giving opportunities for reentrant circuits to reappear.

Another challenge with using this approach is the high incidence of pulmonary vein (PV) stenosis.

Due to the fact that electrical impulses are not conducting from the SA node to the ventricles, the ventricles contract abnormally very rapidly.

As a result, the four chambers of the heart are less able to fill completely with blood between beats, and hence less blood is pumped to the remaining circulatory pathways in the body.

Over time, VT can lead to heart failure or degenerate into ventricular fibrillation, which can result in myocardial infarction.

Although RF catheter ablation as a treatment for VT has been performed, success has been limited particularly to those VT's due to ischemic heart disease.

This may be due to the difficulty in achieving sufficient tissue penetration of RF energy to ablate arrhythmia circuit lying beneath the endocardial scar tissue.

In addition, the ventricles are naturally much thicker than atrial tissues and creating transmural lesions is more challenging when utilizing conventional RF ablation techniques.

This may be due to the irregular endocardial surface of the ventricular trabeculum that may present a technical challenge for ablating electrodes of RF ablation catheters to make adequate tissue contact.

The piezoelectric nature of ultrasound transducers creates limitations for these materials.

One major limitation is when the temperature of the transducer is elevated, the performance decreases steadily until no acoustic waves can be observed.

In both the Schaer et al. and McLaughlin et al. catheters, the amount of irrigation fluid permeating out from the porous membrane or porous tip electrode to cool the tissue-ablation element interface may not be consistent due to its contact with the underlying tissue and therefore may produce a larger or smaller intended ablation area.

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