In Cardiac Electrophysiology

5.1. Nonfluoroscopic Electroanatomical Cardiac Mapping and Noncontact Endocardiac Activation Mapping cardiac mapping is essential for understanding mechanisms of cardiac arrhythmias and for directing curative ablation procedures. Traditional endocardial mapping techniques are time consuming, produce significant X-ray exposure, and are limited by lack of three-dimensional (3D) spatial information. Among the most important new advances in cardiac electro-physiology are 3D mapping systems, such as the nonfluoro-scopic electroanatomical cardiac mapping system (CARTOâ„¢, Biosense, Tirat Hacarmel, Israel) and the noncontact endocardial activation mapping system (Endocardial Solutions, Inc., St. Paul, MN). These mapping systems will be discussed in detail in other chapters of the book.

5.2. Intracardiac Echocardiography several studies have demonstrated that intracardiac echo-cardiography is a useful tool during radiofrequency ablation procedures (17). Potential benefits of direct endocardial visualization during radiofrequency ablative procedures include: (1) enhanced ability to guide ablative procedures and precise anatomical localization of the ablation catheter tip in relation to important endocardial structures (which cannot be visualized with fluoroscopy); (2) reduction in fluoroscopy time; (3) evaluation of catheter-tip tissue contact; (4) confirmation of lesion formation and identification of lesion size and continuity; (5) immediate identification of complications; and (6) provision of a research tool to help understand the critical role played by specific endocardial structures in arrhythmogenesis. Three-dimensional echocardiography is certainly more useful and probably one of the ideal imaging techniques for cardiac elec-trophysiology; however, its quality must be improved before it becomes clinically applicable.

5.3. Magnetically Directed Catheter Manipulation

A recent development in the manipulation of intravascular electrode catheters for various electrophysiological study and mapping/ablation purposes has been the development of using magnetic fields to direct malleable catheters. This technique (Stereotaxis Inc., St. Louis, MO) requires catheterization laboratories fitted with large magnets at the bedside and specially designed low-mass catheters capable of direction by the magnetic field.

The principal advantage in terms of mapping is the ability to turn tight corners because the catheters can be relatively supple, and their movement is controlled by magnetic force without manual torque. In addition, the operator can manipulate the catheter with a "joy stick" from outside the laboratory, thereby reducing long-term radiation exposure. Finally, by retaining coordinates in memory, the system can bring the catheter back to a predetermined site with great accuracy. This system is currently in clinical trials.

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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