Maximum atrial tracking rate for cardiac rhythm management system

A cardiac rhythm management system including:

• a ventricular sensing channel to detect a QRS complex during a cardiac cycle;
• an accelerometer to detect a fiducial of a heart acceleration signal correlative to an aortic valve closure occurring during the cardiac cycle after the QRS complex, and to detect a patient activity level;
• and
• a controller adapted for calculating a maximum atrial tracking rate based at least in part on the activity level and a time interval between the QRS complex and the fiducial.

A cardiac rhythm management system including:

• a ventricular sensing channel to detect a QRS complex during a cardiac cycle;
• means for detecting a fiducial of a heart acceleration signal correlative to an aortic valve closure occurring during the cardiac cycle after the QRS complex, and for detecting a patient activity level;
• and
• a controller adapted for calculating a maximum atrial tracking rate based at least in part on the activity level and a time interval between the QRS complex and the fiducial.

A cardiac rhythm management system including:

• a ventricular sensing channel to detect a QRS complex during a cardiac cycle;
• an impedance sensing circuit to detect a heart impedance signal varying in response to a heart contraction;
• and
• a controller adapted for calculating a maximum atrial tracking rate based at least in part a time interval between the QRS complex and a subsequent maximum slope of the heart impedance signal during the same cardiac cycle as the QRS complex.