Methods and systems for measuring cardiac parameters

Abstract

Methods and systems of the present invention provide for measurement of various cardiac parameters. Methods generally involve causing a change in volume and/or pressure in a heart chamber, measuring the change, and calculating at least one cardiac parameter based on the change. Systems typically include at least one actuator, at least one sensor, and a catheter or other device for positioning at least partially in a heart chamber. In some embodiments, the system may also include a controller, such as a computer or other processor, an external actuator, an external sensor, and/or an ECG device. Methods and systems of the invention may be used to more accurately diagnose cardiac conditions in order to make more informed treatment decisions.

1 - 78 . (canceled)  
     
     
         79 . A system for measuring one or more parameters of a heart, the system comprising: a catheter comprising at least one sensor and at least one actuator for introducing a known volume of fluid into at least one chamber of the heart at a selected time during a heart cycle to effect a volume change in the heart chamber; a fluid source coupled with the catheter for providing fluid to the actuator; and a processor coupled with the catheter for processing data sensed by the at least one sensor.  
     
     
         80 . A system as in  claim 79 , wherein the at least one sensor comprises at least one of a pressure sensor and a volume sensor.  
     
     
         81 . A system as in  claim 80 , wherein the at least one sensor further comprises at least one of a flow sensor for measuring blood flowing from the heart and a vascular pressure sensor for measuring pressure in a vessel extending from the heart.  
     
     
         82 . A system as in  claim 81 , wherein the at least one flow sensor or pressure sensor is disposed in a location to measure flow or pressure in at least one of an aorta, a pulmonary artery, and a coronary artery.  
     
     
         83 . A system as in  claim 79 , wherein the at least one sensor comprises at least one hydrophone.  
     
     
         84 . A system as in  claim 79 , wherein the at least one sensor comprises at least one ultrasound transducer for measuring a distance within a chamber of the heart.  
     
     
         85 . A system as in  claim 84 , wherein the at least one ultrasound transducer comprises: a first pair of ultrasound transducers coupled with the catheter in parallel with a longitudinal axis of the catheter for measuring a first distance between the transducers and the wall of the chamber of the heart; a second pair of ultrasound transducers coupled with the catheter in an orientation 90-degrees rotated from the first pair of transducers for measuring second and third distances to a wall of the heart chamber; and a third pair of ultrasound transducers coupled with the catheter in an orientation 90-degrees rotated from the first and second pairs of transducers for measuring fourth and fifth distances to a wall of the heart chamber.  
     
     
         86 . A system as in  claim 79 , wherein the at least one actuator comprises at least one of a fluid outlet port and an expandable balloon, the expandable balloon being expandable by introducing the fluid into the balloon.  
     
     
         87 . A system as in  claim 79 , further comprising an electrocardiogram device coupled with the processor for measuring the heart cycle.  
     
     
         88 . The system as in  claim 79 , wherein said system is configured to cause a change in at least one of volume and pressure in a heart chamber at a selected time during a heart cycle; measure a change in at least one characteristic of the heart chamber which occurs in response to the change in at least one of volume and pressure; and calculate at least one cardiac performance parameter based on a ratio of the measured change in the characteristic to the caused change.  
     
     
         89 . The system as in  claim 88 , wherein said system is configured to repeat the causing a change, measuring and calculating steps over a series of two or more consecutive heart cycles.  
     
     
         90 . The system as in  claim 88 , wherein said system is configured to measure a change in at least one pressure within the heart chamber.  
     
     
         91 . The system as in  claim 88 , wherein said system is configured to measure a change in at least one volume within the heart chamber.  
     
     
         92 . The system as in  claim 88 , wherein said system is configured to measure a change in at least one pressure and a change in at least one volume within the heart chamber.  
     
     
         93 . The system as in  claim 88 , wherein said system is configured to measure a change in at least one flow rate of blood flowing out of the heart chamber which occurs in response to the volume and/or pressure change; and calculate at least one flow-related parameter of the heart chamber based on a ratio of the measured change in the flow rate to the volume and/or pressure change.