Fig. 8. The strength-duration curves during coronary vein left ventricular pacing in four patients with biventricular pacing with a lead in the right ventricular apex and the lateral wall of the left ventricle using Guidant lead 4512. It appears that there is no substantial difference in the shape of the two curves.

delay. The potential deleterious effects of right ventricular pacing alone in such cases have been established. It seems that left ventricular pacing should be performed when feasible whenever cardiac pacing is required, such as after atrioventricular nodal ablation, to minimize subsequent electrical and mechanical remodeling. Yet, biventricular pacing at present is an imperfect technique for correcting cardiac dyssynchrony. The concept of physiological pacing should always be kept in mind to maximize the benefits of pacing whenever pacing is required, particularly in the presence of left ventricular dysfunction. Nonetheless, the beneficial effects of biventricular pacing will continue to increase clinically if the following important clinical and technical questions can be resolved:

1. What is the impact of cardiac resynchronization therapy on all-cause mortality and sudden cardiac death?

2. Can cardiac resynchronization therapy induce left ventricular reverse remodeling and thus help to prevent, or at least slow, heart failure progression?

3. How can we better select potential responders?

4. What are the optimal pacing sites?

5. How can we best determine the optimal atrioventricular delay?

6. How can we improve the methods for implanting left ventricular leads?

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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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