Systems and methods for determining optimal interventricular pacing delays based on electromechanical delays

Abstract

Techniques are provided for use with implantable medical devices such as pacemakers for optimizing interventricular (VV) pacing delays for use with cardiac resynchronization therapy (CRT). In one example, ventricular electrical depolarization events are detected within a patient in whom the device is implanted. The onset of isovolumic ventricular mechanical contraction is also detected based on cardiomechanical signals detected by the device, such as cardiogenic impedance (Z) signals, S1 heart sounds or left atrial pressure (LAP) signals. Then, an electromechanical time delay (T_QtoVC) between ventricular electrical depolarization and the onset of isovolumic ventricular mechanical contraction is determined. VV pacing delays are set to minimize the time delay to the onset of isovolumic ventricular mechanical contraction. Various techniques for identifying the onset of isovolumic ventricular contraction based on Z, S1 or LAP or other cardiomechanical signals are described. In some examples, CRT nonresponders are specifically identified and/or heart failure progression is tracked.

What is claimed is: 
     
         1 . A method for use with an implantable cardiac rhythm management device for implant within a patient, the method comprising:
 detecting ventricular electrical depolarization within the patient based on electrocardiac signals sensed by the device;   detecting an onset of isovolumic ventricular mechanical contraction within the patient based on cardiomechanical signals sensed by the device;   determining an electromechanical time delay between ventricular electrical depolarization and the onset of ventricular mechanical contraction;   determining pacing locations for interventricular (VV) pacing based on the time delay; and   delivering pacing using the pacing locations.   
     
     
         2 . The method of  claim 1  wherein determining pacing locations for VV pacing based on the time delay includes guiding implant locations. 
     
     
         3 . The method of  claim 1  for use with a device equipped with a multi-pole LV lead having a plurality of selectable electrodes and wherein determining pacing locations for VV pacing based on the time delay includes identifying preferred electrodes for VV pacing.