Bowditch Revisited: Defining the Optimum Heart Rate Range in Chronic Heart Failure
Bowditch Revisited: Defining the Optimum Heart Rate Range in Chronic Heart Failure
The investigators are examining the relationship between heart rate and heart contraction in
 patients with heart failure and pacemakers, aiming to improve quality of life.
Heart rate lowering is a cornerstone of the management of chronic heart failure (CHF) and the
 degree of lowering is closely related to improvements in longevity, hospitalisation rate and
 heart function. The investigators have shown that increasing heart rates using pacemakers
 does not increase exercise capacity in CHF patients. This might be because the optimal heart
 rate range for contraction is narrower for patients with CHF. At higher heart rates, heart
 contraction might be less strong. The investigators now want to examine the relationship
 between heart rate and heart contraction in patients with heart failure and pacemakers.
 Tailored pacemaker heart rate setting's, individually optimised for heart contractility as
 assessed by cardiac ultrasound, will be investigated to examine the effects on exercise
 tolerance .
Inclusion Criteria:

 -  stable CHF

 -  Cardiac Resynchronisation Therapy (CRT) device for >3 months,

 -  able to walk on treadmill

 Exclusion Criteria:

 -  unable to walk on treadmill,

 -  unstable angina pectoris

 -  uncontrolled heart rate

 -  prescribed calcium channel blocker

 -  significant aortic stenosis

 -  significant airways disease