Cardiac Resynchronization Therapy, Dyspnea and Exercise Tolerance in Patients With Congestive Heart Failure (CHF)

A new therapy for patients with advanced heart failure (HF) involves the implantation of a specialized pacemaker device (Cardiac Resynchronization Therapy, CRT) that attempts to restore the synchronized contraction of the ventricular chambers of the heart. In some people, CRT improves exertional breathlessness and allows them to exercise for longer periods. However, to date, the mechanisms by which CRT improves symptoms and exercise tolerance is unknown. This study will use in-depth cardiopulmonary exercise testing and pulmonary function testing to explore these mechanisms in greater detail.