Method for measuring baroreflex sensitivity and therapy optimization in heart failure patients

Abstract

A method and apparatus for determining the baroreflex sensitivity in a chronic heart failure patient and a method for chronic heart therapy evaluation. The method including providing a series of pacing stimuli to the heart of a chronic heart failure patient and measuring the change in pulse pressure and the change in cycle length incident to each pacing series. The changes being plotted to produce a line indicative of baroreflex sensitivity. The apparatus including a pacemaker having sensors for monitoring both cycle length and pulse pressure wherein the sensors may be integral or separate from the pacemaker. The method for evaluating chronic heart failure therapies including administering a series of therapies and evaluating each therapy based on the resultant increase of the patient's baroreflex sensitivity.

What is claimed is:  
     
         1 . A method for measuring baroreflex sensitivity, comprising: 
 pacing a heart for a plurality of paced heart beats, wherein the plurality of paced beats comprise a pacing series and each of the pacing series are followed by a plurality of intrinsic heart beats, wherein the plurality of intrinsic heart beats comprise an intrinsic series 
 measuring a change in pulse pressure during the pacing series;  
   measuring a change in intrinsic cycle length resulting from the change in pulse pressure during the pacing series; and    calculating baroreflex sensitivity from the change in pulse pressure measurements and the change in intrinsic cycle length measurements after a plurality of pacing series.    
     
     
         2 . A method, as in  claim 1 , further comprising evaluating the efficacy of a plurality of therapies based on the calculated baroreflex sensitivity and selecting the therapy providing the highest baroreflex sensitivity.  
     
     
         3 . A method, as in  claim 1 , wherein the pacing parameter includes at least one of AV delay, right ventricle stimulation, left ventricle stimulation, and atrial sensing.  
     
     
         4 . A method, as in  claim 1 , wherein the change in pulse pressure is measured relative to the intrinsic pulse pressure at a quiet time.  
     
     
         5 . A method, as in  claim 4 , wherein pulse pressure is measured using a sensor selected from the group consisting of a Millar pressure transducer, an RV pressure transducer, a LV pressure transducer, an RV impedance sensor, a LV impedance sensor, an aortic cuff, an accelerometer, an echo catheter, a Doppler echo device, an external pressure cuff, an external impedance sensor, a radial tonometer, and a plethysmogram sensor.  
     
     
         6 . A method, as in  claim 4 , wherein pulse pressure is measured using a method selected from the group consisting of Doppler echo, radial tonometry, thermodilution, dye dilution, MUGA, plethysmography, Fick method, acetylene rebreathing technique and carbon dioxide rebreathing technique.  
     
     
         7 . A method, as in  claim 1 , wherein the change in intrinsic cycle length is measured using one of an electrocardiographic sensor, an atrial electrographic sensor and a ventricular electrographic sensor.  
     
     
         8 . A method for measuring baroreflex sensitivity, comprising: 
 a step for pacing a heart for a plurality of paced heart beats, wherein the plurality of paced beats comprise a pacing series and each of the pacing series are followed by a plurality of intrinsic heart beats, wherein the plurality of intrinsic heart beats comprise an intrinsic series;    a step for determining a change in pulse pressure during the pacing series;    a step for determining a change in intrinsic cycle length resulting from the change in pulse pressure; and    a step for determing baroreflex sensitivity based on the change of cycle length divided by the change in pulse pressure.    
     
     
         9 . A method, as in  claim 8 , further comprising a step for evaluating the efficacy of a plurality of therapies based on the calculated baroreflex sensitivity and a step for selecting the therapy providing the highest baroreflex sensitivity.  
     
     
         10 . An apparatus for measuring baroreflex sensitivity, comprising: 
 a pacemaker having at least one variable parameter capable of altering a pulse pressure in a patient;    a first sensor for sensing a cycle length in a heart; and    a second sensor for sensing the pulse pressure in the patient.    
     
     
         11 . An apparatus, as in  claim 10 , wherein the first sensor is selected from the group consisting of an electrocardiographic sensor, an atrial electrographic sensor and a ventricular electrographic sensor.  
     
     
         12 . An apparatus, as in  claim 10 , wherein the second sensor is selected from the group consisting of a Millar pressure transducer, an RV pressure transducer, a LV pressure transducer, an RV impedance sensor, a LV impedance sensor, an aortic cuff, an accelerometer, an echo catheter, a Doppler echo device, an external pressure cuff, an external impedance sensor, a radial tonometer, and a plethysmogram sensor.  
     
     
         13 . An apparatus, as in  claim 10 , further comprising a visual display connected to the pacemaker to display data indicative of the baroreflex sensitivity.  
     
     
         14 . An apparatus, as in  claim 13 , wherein the visual display is connected to the pacemaker by radio frequency.  
     
     
         15 . An apparatus, as in  claim 13 , wherein the visual display is connected to the pacemaker using a conductive wire.  
     
     
         16 . An apparatus, as in  claim 10 , further comprising an external programmer, the programmer comprising an external processor and a display wherein the external processor receives information from processor in the implanted device and displays data indicative of baroreflex sensitivity on the display.  
     
     
         17 . An apparatus, as in  claim 16 , further comprising an implanted transmitter connected to the processor implanted in the patient and a receiver connected to the external processor in the external programmer wherein the implanted transmitter transmits data indicative of baroreflex sensitivity to the receiver.  
     
     
         18 . An apparatus, as in  claim 17 , further comprising an implanted receiver connected to the processor implanted in the patient and a transmitter connected to the external processor in the external programmer wherein the transmitter transmits data to the receiver to alter the pacing parameters.  
     
     
         19 . An apparatus for measuring baroreflex sensitivity, comprising: 
 a means for altering a pulse pressure in a patient;    a means for sensing a cycle length in a heart; and    a means for sensing the pulse pressure in the patient.    
     
     
         20 . A method for evaluating a cardiac rehabilitative therapy, comprising: 
 measuring baroreflex sensitivity before the cardiac rehabilitative therapy;    providing a cardiac rehabilitative therapy to the CHF patient; measuring baroreflex sensitivity after the cardiac rehabilitative therapy; and    evaluating results of the rehabilitative therapy based on a comparison of a first measurement of baroreflex sensitivity before the cardiac rehabilitative therapy and a second measurement of baroreflex sensitivity after the cardiac rehabilitative therapy.    
     
     
         21 . A method for evaluating a cardiac rehabilitative therapy, comprising: 
 a step for measuring baroreflex sensitivity before the cardiac rehabilitative therapy;    a step for providing a cardiac rehabilitative therapy to the CHF patient; a step for measuring baroreflex sensitivity after the step of providing cardiac rehabilitative therapy; and    a step for evaluating results of the rehabilitative therapy based on a comparison of a first measurement of baroreflex sensitivity before the cardiac rehabilitative therapy and a second measurement of baroreflex sensitivity after the cardiac rehabilitative therapy.