Systems and methods for leadless cardiac resynchronization therapy

Abstract

Techniques and systems for monitoring cardiac arrhythmias and delivering electrical stimulation therapy using a subcutaneous device (e.g. subcutaneous implantable (SD)) is described. In one or more other embodiments, SD is implanted into a patient's heart. Electrical signals are then sensed which includes moderately lengthened QRS duration data from the patient's heart. A determination is made as to whether cardiac resynchronization pacing therapy (CRT pacing) is appropriate based upon the moderately lengthened QRS duration in the sensed electrical signals. The CRT pacing pulses are delivered to the heart using electrodes. In one or more embodiments, the SD can switch between fusion pacing and biventricular pacing based upon data (e.g. moderately lengthened QRS, etc.) sensed from the heart.

What is claimed is: 
     
       1. A method of using a subcutaneous device (SD) in a patient and a leadless pacing device (LPD) in the patient's heart, on the patient's heart, or in a substernal location of the patient, the method comprising:
 sensing at least one electrical signals signal which includes moderately lengthened QRS duration data from the patient's heart using the SD, wherein sensing the at least one electrical signal which includes moderately lengthened QRS duration data from the patient's heart using the SD comprises evaluating an RVs-LVs interval from sensing markers determined by at least one of the LPD or the SD; 
 employing the SD to determine whether cardiac resynchronization pacing therapy (CRT pacing) is appropriate based upon the moderately lengthened QRS duration data in the sensed electrical signals signal; 
 employing the SD to determine timing of CRT pacing pulses for delivery to cardiac tissue through the LPD and sending signals indicative thereof to the LPD responsive to the sent indicative signals; 
 delivering the CRT pacing pulses to the heart using the LPD based on the signals sent by the SD indicative of the timing of the CRT pacing pulses; 
 thereafter sensing at least one subsequent electrical signals signal from the patient's heart using the SD; and 
 determining, by the SD based on the subsequent electrical signals signal, whether the CRT pacing by the LPD provided efficacious resynchronization and whether the delivery and timing of subsequent CRT pacing pulses should be modified. 
 
     
     
       2. A method of claim of  1  9, wherein the moderately lengthened QRS duration data corresponds to a QRS width in a range of 120-160 milliseconds (ms). 
     
     
       3. A method of claim  1  9, wherein the at least one electrical signal comprises a far-field electrogram (EGM), the method further comprising:
 evaluating intrinsic ventricular conduction based upon the moderately lengthened QRS duration data from a the far-field electrogram ( EGM). 
 
     
     
       4. A method of  claim 1  further comprising:
 evaluating an RVs-LVs interval from sensing markers is automatically evaluated by the LPD or the SD. 
 
     
     
       5. A method of claim  4  1 further comprising switching between fusion pacing and biventricular pacing based on the RVs-LVs interval, wherein the RVs-LVs interval not exceeding 80 milliseconds (ms) corresponds to fusion pacing while the RVs-LVs interval being greater than 80 ms switches corresponds to biventricular pacing. 
     
     
       6. A method of  claim 1  wherein the SD generates a signal to the LPD to switch to another CRT pacing. 
     
     
       7. A method of claim  6  1further comprising switching from the CRT pacing to another CRT pacing. 
     
     
       8. A method of  claim 7  wherein the SD generates a signal to the LPD to cause switching from the CRT pacing to the another CRT pacing. 
     
     
       9. A method of  claim 8  of using a subcutaneous device (SD) in a patient and a leadless pacing device (LPD) in the patient's heart, on the patient's heart, or in a substernal location of the patient, the method comprising:
 sensing at least one electrical signal which includes moderately lengthened QRS duration data from the patient's heart using the SD; 
 employing the SD to determine whether cardiac resynchronization pacing therapy (CRT pacing) is appropriate based upon the moderately lengthened QRS duration data in the sensed electrical signal; 
 employing the SD to determine timing of CRT pacing pulses for delivery to cardiac tissue through the LPD and sending signals indicative thereof to the LPD; 
 delivering the CRT pacing pulses to the heart using the LPD based on the signals sent by the SD indicative of the timing of the CRT pacing pulses; 
 thereafter sensing at least one subsequent electrical signal from the patient's heart using the SD; 
 determining, by the SD based on the subsequent electrical signal, whether the CRT pacing by the LPD provided efficacious resynchronization and whether the delivery and timing of subsequent CRT pacing pulses should be modified; and 
 switching from the CRT pacing to another CRT pacing, 
 wherein the SD generates a signal to the LPD to cause the switching from the CRT pacing to the another CRT pacing; and  
 wherein each of the CRT pacing and the another CRT pacing being is a respective one of fusion pacing and biventricular pacing. 
 
     
     
       10. A method of  claim 9  further comprising:
 sensing another electrical signal from the cardiac tissue patient's heart via the LPD, the another electrical signal indicating fusion pacing being is appropriate pacing to deliver to cardiac tissue; and 
 generatingsending a signal to the SD from the LPD communicating fusion pacing data. 
 
     
     
       11. A method of  claim 10  further comprising:
 processing the another electrical signal; and 
 
       determining by the SD whether the another electrical signal indicates that a switch to another CRT fusion pacing should occur. 
     
     
       12. A method of  claim 7  wherein the SD generates a signal to the LPD either confirming or overriding switching to the another CRT pacing. 
     
     
       13. A method of  claim 12  wherein the CRT pacing being one of fusion pacing and biventricular pacing. 
     
     
       14. A method of  claim 12  further comprising:
 generating an overriding signal from the SD to the LPD. 
 
     
     
       15. A method of  claim 14  wherein the SD generates a signal to the LPD confirming switching to another CRT pacing. 
     
     
       16. A method of claim  1  further comprising 9, wherein sensing the at least one electrical signal comprises:
 sensing the at least one electrical signals signal from a substernally placed lead extending from the SD. 
 
     
     
       17. A method comprising:
 sensing at least one electrical signals which includes moderately lengthened QRS duration data signal from the a patient's heart using a subcutaneous device (SD); 
 determining that the at least one electrical signal includes moderately lengthened QRS duration data;  
 determining whether that a fusion pacing mode of cardiac resynchronization pacing therapy (CRT pacing) is appropriate based upon the determination that the at least one electrical signal includes moderately lengthened QRS duration in the sensed electrical signals data; and 
 delivering the CRT pacing pulses to the heart according to the fusion pacing mode using a leadless pacing device (LPD) based on a determination that the fusion pacing mode is appropriate. 
 
     
     
       18. A method of claim of  17  wherein the moderately lengthened QRS duration data corresponds to a QRS width in the range of 120-160 milliseconds (ms). 
     
     
       19. A method of  claim 17  wherein the at least one electrical signal comprises a far-field electrogram (EGM), the method further comprising:
 evaluating intrinsic ventricular conduction based upon the moderately lengthened QRS duration data from a the far-field EGM. 
 
     
     
       20. A method of  claim 17  further comprising wherein determining that the at least one electrical signal which includes moderately lengthened QRS duration data comprises:
 evaluating an RVs-LVs interval from sensing markers is automatically evaluated determined by at least one of the LPD or the SD. 
 
     
     
       21. A method of  claim 20  further comprising switching between the fusion pacing mode and a biventricular pacing mode based on the RVs-LVs interval, wherein the RVs-LVs interval not exceeding 80 milliseconds (ms) corresponds to the fusion pacing mode while the RVs-LVs interval being greater than 80 ms switches corresponds to the biventricular pacing mode. 
     
     
       22. A system for cardiac pacing comprising:
 a subcutaneous device (SD) configured for implantation in a patient; 
 a leadless pacing device (LPD) configured for implantation in the patient's heart, on the patient's heart, or in a substernal location of the patient; 
 sensing means for sensing at least one electrical signals signal which includes moderately lengthened QRS duration data from the patient's heart using the SD, wherein the sensing means for sensing the at least one electrical signal which includes moderately lengthened QRS duration data from the patient's heart comprises means for evaluating an RVs-LVs interval from sensing markers determined by at least one of the LPD or the SD; 
 processing means for employing the SD to determine determining whether cardiac resynchronization pacing therapy (CRT pacing) is appropriate based upon the moderately lengthened QRS duration data in the sensed electrical signals signal; 
 processing means for employing the SD to determine determining timing of CRT pacing pulses for delivery to cardiac tissue through the LPD and sending signals indicative thereof to the LPD responsive to the sent indicative signals; 
 delivering means for delivering the CRT pacing pulses to the heart using the LPD; 
 thereafter sensing means for sensing at least one subsequent electrical signals signal from the patient's heart using the SD; and 
 processing means for determining, by the SD based on the subsequent electrical signals signal, whether the CRT pacing by the LPD provided efficacious resynchronization and whether the delivery and timing of subsequent CRT pacing pulses should be modified. 
 
     
     
       23. A system of claim of  22  wherein the moderately lengthened QRS corresponds to a QRS width in the range of 120-160 ms. 
     
     
       24. A system of  claim 22 , wherein the at least one electrical signal comprises a far-field electrogram (EGM), the system further comprising:
 means for evaluating intrinsic ventricular conduction based upon the moderately lengthened QRS duration data from athe far-field EGM. 
 
     
     
       25. A system of  claim 22  further comprising:
 evaluating an RVs-LVs interval from sensing markers is automatically evaluated by the LPD or the SD. 
 
     
     
       26. A system of claim  25  22 further comprising means for switching between fusion pacing and biventricular pacing based on the RVs-LVs interval, wherein the RVs-LVs interval not exceeding 80 milliseconds (ms) corresponds to fusion pacing while the RVs-LVs interval greater than 80 ms switches corresponds to biventricular pacing. 
     
     
       27. A method of using a subcutaneous device (SD) in a patient and at least one leadless pacing device (LPD) in the patient's heart, on the patient's heart, or in a substernal location of the patient, the method comprising:
 sensing, by at least one of the SD or the at least one LPD, at least one electrical signal from the patient's heart;   determining, by the SD, an intrinsic ventricular activation duration in the at least one sensed electrical signal, wherein determining, by the SD, the intrinsic ventricular activation duration comprises determining, by the SD, an RVs-LVs interval from sensing markers determined by at least one of the LPD or the SD;   comparing, by the SD, the determined intrinsic ventricular activation duration to at least one moderately lengthened ventricular activation duration threshold;   selecting, by the SD, either a first ventricular pacing mode or a second ventricular pacing mode based on the comparison of the determined intrinsic ventricular activation duration to the at least one moderately lengthened ventricular activation duration threshold, wherein at least one of the first ventricular pacing mode or the second ventricular pacing mode comprises a cardiac resynchronization therapy (CRT) pacing mode; and   delivering ventricular pacing to the heart according to the selected one of the first ventricular pacing mode or the second ventricular pacing mode using at least one of the SD or the at least one LPD in response to the selection.    
     
     
       28. A method of claim 33,
 wherein sensing, by at least one of the SD or the at least one LPD, the at least one electrical signal from the patient's heart comprises sensing, by the SD, a far-field electrogram (EGM),   wherein determining, by the SD, the intrinsic ventricular activation duration comprises determining, by the SD, an intrinsic QRS duration in the far-field electrogram, and   wherein comparing, by the SD, the determined intrinsic ventricular activation duration to the at least one moderately lengthened ventricular activation duration threshold comprises comparing, by the SD, the determined intrinsic QRS duration to at least one moderately lengthened QRS duration threshold.    
     
     
       29. A method of claim 28, wherein the at least one moderately lengthened QRS duration threshold is 150 milliseconds (ms).  
     
     
       30. A method of claim 28, wherein the at least one moderately lengthened QRS duration threshold is 160 milliseconds (ms).  
     
     
       31. A method of claim 27, wherein the at least one moderately lengthened ventricular activation threshold is 80 milliseconds (ms).  
     
     
       32. A method of using a subcutaneous device (SD) in a patient and at least one leadless pacing device (LPD) in the patient's heart, on the patient's heart, or in a substernal location of the patient, the method comprising:
 sensing, by at least one of the SD or the at least one LPD, at least one electrical signal from the patient's heart;   determining, by the SD, an intrinsic ventricular activation duration in the at least one sensed electrical signal;   comparing, by the SD, the determined intrinsic ventricular activation duration to at least one moderately lengthened ventricular activation duration threshold;   selecting, by the SD, either a first ventricular pacing mode or a second ventricular pacing mode based on the comparison of the determined intrinsic ventricular activation duration to the at least one moderately lengthened ventricular activation duration threshold, wherein at least one of the first ventricular pacing mode or the second ventricular pacing mode comprises a cardiac resynchronization therapy (CRT) pacing mode; and   delivering ventricular pacing to the heart according to the selected one of the first ventricular pacing mode or the second ventricular pacing mode using at least one of the SD or the at least one LPD in response to the selection,   wherein the first ventricular pacing mode comprises fusion pacing and the second ventricular pacing mode comprises biventricular pacing, and   wherein selecting, by the SD, either the first ventricular pacing mode or the second ventricular pacing mode comprises selecting, by the SD, fusion pacing based on the intrinsic ventricular activation duration being less than the at least one moderately lengthened ventricular activation duration threshold.    
     
     
       33. A method of using a subcutaneous device (SD) in a patient and at least one leadless pacing device (LPD) in the patient's heart, on the patient's heart, or in a substernal location of the patient, the method comprising:
 sensing, by at least one of the SD or the at least one LPD, at least one electrical signal from the patient's heart;   determining, by the SD, an intrinsic ventricular activation duration in the at least one sensed electrical signal;   comparing, by the SD, the determined intrinsic ventricular activation duration to at least one moderately lengthened ventricular activation duration threshold;   selecting, by the SD, either a first ventricular pacing mode or a second ventricular pacing mode based on the comparison of the determined intrinsic ventricular activation duration to the at least one moderately lengthened ventricular activation duration threshold, wherein at least one of the first ventricular pacing mode or the second ventricular pacing mode comprises a cardiac resynchronization therapy (CRT) pacing mode; and   delivering ventricular pacing to the heart according to the selected one of the first ventricular pacing mode or the second ventricular pacing mode using at least one of the SD or the at least one LPD in response to the selection,   wherein the first ventricular pacing mode comprises fusion pacing and the second ventricular pacing mode comprises biventricular pacing, and   wherein selecting, by the SD, either the first ventricular pacing mode or the second ventricular pacing mode comprises selecting, by the SD, biventricular pacing based on the intrinsic ventricular activation duration being greater than the at least one moderately lengthened ventricular activation duration threshold.    
     
     
       34. A system comprising:
 a subcutaneous device (SD) configured for implantation in a patient; and   at least one leadless pacing device (LPD) configured for implantation in the patient's heart, on the patient's heart, or in a substernal location of the patient,   wherein at least one of the SD or the at least one LPD is configured to sense at least one electrical signal from the patient's heart,   wherein the SD is configured to:
 determine an intrinsic ventricular activation duration in the at least one sensed electrical signal, wherein the SD is configured to determine the intrinsic ventricular activation duration by at least determining an RVs-LVs interval from sensing markers determined by at least one of the LPD or the SD; 
 compare the determined intrinsic ventricular activation duration to at least one moderately lengthened ventricular activation duration threshold; and 
 select either a first ventricular pacing mode or a second ventricular pacing mode based on the comparison of the determined intrinsic ventricular activation duration to the at least one moderately lengthened ventricular activation duration threshold, wherein at least one of the first ventricular pacing mode or the second ventricular pacing mode comprises a cardiac resynchronization therapy (CRT) pacing mode, and 
   wherein at least one of the SD or the at least one LPD is configured to deliver ventricular pacing to the heart according to the selected one of the first ventricular pacing mode or the second ventricular pacing mode in response to the selection.    
     
     
       35. A system of claim 39, wherein the at least one moderately lengthened ventricular activation duration threshold comprises at least one moderately lengthened QRS duration threshold, and the SD is configured to:
 sense a far-field electrogram (EGM);   determine an intrinsic QRS duration in the far-field electrogram as the intrinsic ventricular activation duration; and   compare the determined intrinsic QRS duration to the at least one moderately lengthened QRS duration threshold.    
     
     
       36. A system of claim 35, wherein the at least one moderately lengthened QRS duration threshold comprises 150 milliseconds (ms).  
     
     
       37. A system of claim 35, wherein the at least one moderately lengthened QRS duration threshold comprises 160 milliseconds (ms).  
     
     
       38. A system of claim 34, wherein the at least one moderately lengthened ventricular activation threshold comprises 80 milliseconds (ms).  
     
     
       39. A system comprising:
 a subcutaneous device (SD) configured for implantation in a patient; and   at least one leadless pacing device (LPD) configured for implantation in the patient's heart, on the patient's heart, or in a substernal location of the patient,   wherein at least one of the SD or the at least one LPD is configured to sense at least one electrical signal from the patient's heart,   wherein the SD is configured to:
 determine an intrinsic ventricular activation duration in the at least one sensed electrical signal; 
 compare the determined intrinsic ventricular activation duration to at least one moderately lengthened ventricular activation duration threshold; and 
 select either a first ventricular pacing mode or a second ventricular pacing mode based on the comparison of the determined intrinsic ventricular activation duration to the at least one moderately lengthened ventricular activation duration threshold, wherein at least one of the first ventricular pacing mode or the second ventricular pacing mode comprises a cardiac resynchronization therapy (CRT) pacing mode, and 
   wherein at least one of the SD or the at least one LPD is configured to deliver ventricular pacing to the heart according to the selected one of the first ventricular pacing mode or the second ventricular pacing mode in response to the selection,   wherein the first ventricular pacing mode comprises fusion pacing and the second ventricular pacing mode comprises biventricular pacing, and   wherein the SD is configured to:
 select fusion pacing based on the intrinsic ventricular activation duration being less than the at least one moderately lengthened ventricular activation duration threshold; and 
 select biventricular pacing based on the intrinsic ventricular activation duration being greater than the at least one moderately lengthened ventricular activation duration threshold.  
   
     
     
       40. A method for delivering cardiac resynchronization therapy (CRT) to a patient using a medical device system comprising one or more implantable medical devices, the medical device system configured to deliver the CRT according to both a biventricular pacing mode and a fusion pacing mode using the one or more implantable medical devices, the method comprising:
 sensing, by sensing circuity of the medical device system, at least one electrical signal from a heart of the patient;   determining, by processing circuitry of the medical device system, an intrinsic ventricular activation duration in the sensed electrical signal;   comparing, by the processing circuitry, the determined intrinsic ventricular activation duration to at least one moderately lengthened ventricular activation duration threshold;   selecting, by the processing circuitry, either the biventricular pacing mode or the fusion pacing mode based upon the comparison of the determined intrinsic ventricular activation duration to the at least one moderately lengthened ventricular activation duration threshold; and   delivering the ventricular pacing to the heart according to the selected one of the biventricular pacing mode or the fusion pacing mode using at least one of the one or more implantable medical devices.    
     
     
       41. A method of claim 40, wherein determining the intrinsic ventricular activation duration comprises determining at least one of an intrinsic QRS duration in a far-field electrogram or an RVs-LVs interval.  
     
     
       42. A method of claim 40, wherein selecting either the biventricular pacing mode or the fusion pacing mode comprises selecting the fusion pacing mode based on the intrinsic ventricular activation duration being less than the at least one moderately lengthened ventricular activation duration threshold.  
     
     
       43. A method of claim 40, wherein selecting either the biventricular pacing mode or the fusion pacing mode comprises selecting the biventricular pacing mode based on the intrinsic ventricular activation duration being greater than the at least one moderately lengthened ventricular activation duration threshold.  
     
     
       44. A medical device system configured to deliver cardiac resynchronization therapy (CRT) to a patient according to both a biventricular pacing mode and a fusion pacing mode using one or more implantable medical devices, the system comprising:
 sensing circuity configured to sense at least one electrical signal from a heart of the patient; and   processing circuitry configured to:
 determine an intrinsic ventricular activation duration in the sensed electrical signal; 
 compare the determined intrinsic ventricular activation duration to at least one moderately lengthened ventricular activation duration threshold; 
 select either the biventricular pacing mode or the fusion pacing mode based upon the comparison of the determined intrinsic ventricular activation duration to the at least one moderately lengthened ventricular activation duration threshold; and 
 control delivery of the ventricular pacing to the heart according to the selected one of the biventricular pacing mode or the fusion pacing mode by at least one of the one or more implantable medical devices.  
   
     
     
       45. A system of claim 44, wherein the processing circuitry is configured to determine the intrinsic ventricular activation duration by at least determining at least one of an intrinsic QRS duration in a far-field electrogram or an RVs-LVs interval.  
     
     
       46. A system of claim 44, wherein the processing circuitry is configured to:
 select the fusion pacing mode based on the intrinsic ventricular activation duration being less than the at least one moderately lengthened ventricular activation duration threshold; and   select the biventricular pacing mode based on the intrinsic ventricular activation duration being greater than the at least one moderately lengthened ventricular activation duration threshold.    
     
     
       47. A method of claim 33,
 wherein sensing, by at least one of the SD or the at least one LPD, the at least one electrical signal from the patient's heart comprises sensing, by the SD, a far-field electrogram (EGM),   wherein determining, by the SD, the intrinsic ventricular activation duration comprises determining, by the SD, an intrinsic QRS duration in the far-field electrogram, and   wherein comparing, by the SD, the determined intrinsic ventricular activation duration to the at least one moderately lengthened ventricular activation duration threshold comprises comparing, by the SD, the determined intrinsic QRS duration to at least one moderately lengthened QRS duration threshold.    
     
     
       48. A method of claim 47, wherein the at least one moderately lengthened QRS duration threshold is 150 milliseconds (ms).  
     
     
       49. A method of claim 47, wherein the at least one moderately lengthened QRS duration threshold is 160 milliseconds (ms).