Implantable medical device employing sonomicrometer output signals for detection and measurement of cardiac mechanical function

A method of operating an implantable medical device in relation to cardiac mechanical function of a first heart chamber during a heart cycle comprising:

• implanting a first lead bearing a first sonomicrometer crystal at a first location of the heart outside the first heart chamber;
• implanting a second lead bearing a second sonomicrometer crystal at a second location of the heart outside the first heart chamber, whereby the first and second locations define a vector across and through a substantial portion of the first heart chamber;
• and
• coupling the first and second endocardial leads to an implantable medical device, and operating the implantable medical device by:
• during one or more heart cycle, periodically energizing one of the first and second sonomicrometer crystals to emit an ultrasonic frequency emitted signal that causes the other of the first and second sonomicrometer crystals to develop an ultrasonic frequency sense signal;
• determining the distance between the first and second sonomicrometer crystals as a function of the time delay between emission of the emitted signal and sensing of the respective sense signal;
• and
• deriving and storing data representing one or more of contractility and cardiac output of the first heart chamber from the determined distances in the implantable medical device.

A method of operating an implantable medical device comprising a plurality of leads and an implantable medical device circuit enclosed within a hermetically sealed housing to determine dimensional changes or motion of a first heart chamber due to mechanical movement of the heart chamber during a heart cycle comprising:

• implanting a first endocardial lead bearing a first sonomicrometer crystal through a venous pathway into a second heart chamber and disposing the first sonomicrometer crystal in association with the septum separating the first heart chamber from the second heart chamber, whereby the first sonomicrometer crystal is oriented toward but outside the first heart chamber;
• implanting a second endocardial lead bearing a second sonomicrometer crystal through a venous pathway into a coronary vessel whereby the first and second sonomicrometer crystals are arranged in a vector extending through the first heart chamber;
• coupling the first and second endocardial leads to the implantable medical device circuit, and operating the implantable medical device by:
• during one or more heart cycle, periodically energizing one of the first and second sonomicrometer crystals to emit an ultrasonic frequency emitted signal that causes the other of the first and second sonomicrometer crystals to develop an ultrasonic frequency sense signal;
• and
• at each emission during the one or more heart cycle, determining the distance between the first and second sonomicrometer crystals as a function of the time delay between emission of the emitted signal and sensing of the respective sense signal, whereby the mechanical motion of the first heart chamber over the heart cycle can be determined without entering the first heart chamber including the wall of the first heart chamber.

A method of determining dimensional changes in the left ventricle due to mechanical movement of the left ventricle during the heart cycle comprising:

• implanting a first endocardial lead bearing a first sonomicrometer crystal through a venous pathway with the first sonomicrometer crystal lodged within the right ventricle separated from the left ventricle by the septal wall;
• implanting a second endocardial lead bearing a second sonomicrometer crystal through a venous pathway through the right atrium and the ostium of the coronary sinus such that the second sonomicrometer crystal is lodged within a coronary vessel in relation to the left ventricle whereby the first and second sonomicrometer crystals are arranged in a vector through and across a substantial portion of the left ventricle;
• during one or more heart cycle, periodically energizing one of the first and second sonomicrometer crystals to emit an ultrasonic frequency emitted signal that causes the other of the first and second sonomicrometer crystals to develop an ultrasonic frequency sense signal;
• and
• at each emission during the one or more heart cycle, determining the distance between the first and second sonomicrometer crystals as a function of the time delay between emission of the emitted signal and sensing of the respective sense signal, whereby the mechanical motion of the left ventricle over the heart cycle can be determined without entering the left ventricle.

A method of determining mechanical movement of the atria during the heart cycle comprising:

• implanting a first endocardial lead bearing a first sonomicrometer crystal through a venous pathway with the first sonomicrometer crystal lodged within the right ventricle;
• implanting a second endocardial lead bearing a second sonomicrometer crystal through a venous pathway with the second sonomicrometer crystal lodged in or along one of the left and right atrium, whereby the first and second sonomicrometer crystals are arranged in a vector through the one of the right and left atrium;
• during one or more heart cycle, periodically energizing one of the first and second sonomicrometer crystals to emit an ultrasonic frequency emitted signal that causes the other of the first and second sonomicrometer crystals to develop an ultrasonic frequency sense signal;
• and
• at each emission during the one or more heart cycle, determining the distance between the first and second sonomicrometer crystals as a function of the time delay between emission of the emitted signal and sensing of the respective sense signal, whereby the mechanical motion of the atria can be determined.

A method of pacing the right and left ventricles to alleviate symptoms of heart failure comprising:

• implanting a first lead bearing a first sonomicrometer crystal at a first location of the heart outside the left ventricle;
• implanting a second lead bearing a second sonomicrometer crystal at a second location of the heart outside the left ventricle, whereby the first and second locations define a vector across and through a substantial portion of the left ventricle;
• and
• coupling an implantable medical device to the first and second leads, and operating the implantable medical device by:
• repetitively timing a pacing escape interval establishing paced heart cycles:
• delivering a first pacing pulse to one of the right and left ventricles at the time-out of each pacing escape interval and a second pacing pulse to the other of the right and left ventricles separated in time from the first pacing pulse by a pace delay;
• during one or more heart cycle, periodically energizing one of the first and second sonomicrometer crystals to emit an ultrasonic frequency emitted signal that causes the other of the first and second sonomicrometer crystals to develop an ultrasonic frequency sense signal;
• at each emission during the one or more heart cycle, determining the distance between the first and second sonomicrometer crystals as a function of the time delay between emission of the emitted signal and sensing of the respective sense signal, whereby the mechanical motion of the left ventricle over the heart cycle and cardiac output from the left ventricle can be assessed without entering the left ventricle;
• and
• adjusting the pace delay to maximize the assessed cardiac output.

An implantable medical device comprising a plurality of leads and an implantable medical device circuit enclosed within a hermetically sealed housing comprising:

• a first lead bearing a first sonomicrometer crystal at a first location of the heart outside a first heart chamber and coupled to the implantable medical device circuit;
• a second lead bearing a second sonomicrometer crystal at a second location of the heart outside the first heart chamber and coupled to the implantable medical device circuit, whereby the first and second locations define a vector across and through a substantial portion of the first heart chamber;
• means operable during one or more heart cycle for periodically energizing one of the first and second sonomicrometer crystals to emit an ultrasonic frequency emitted signal that causes the other of the first and second sonomicrometer crystals to develop an ultrasonic frequency sense signal;
• means for determining the distance between the first and second sonomicrometer crystals as a function of the time delay between emission of the emitted signal and sensing of the respective sense signal;
• and
• means for adjusting the operation of the implantable medical device as a function of the determined distances between the first and second sonomicrometer crystals during a heart cycle.

An implantable medical device comprising a plurality of leads and an implantable medical device circuit enclosed within a hermetically sealed housing comprising:

• a first lead bearing a first sonomicrometer crystal at a first location of the heart outside a first heart chamber and coupled to the implantable medical device circuit;
• a second lead bearing a second sonomicrometer crystal at a second location of the heart outside the first heart chamber and coupled to the implantable medical device circuit, whereby the first and second locations define a vector across and through a substantial portion of the first heart chamber;
• means operable during one or more heart cycle for periodically energizing one of the first and second sonomicrometer crystals to emit an ultrasonic frequency emitted signal that causes the other of the first and second sonomicrometer crystals to develop an ultrasonic frequency sense signal;
• means for determining the distance between the first and second sonomicrometer crystals as a function of the time delay between emission of the emitted signal and sensing of the respective sense signal;
• and
• means for deriving and storing data representing one or more of contractility and cardiac output of the first heart chamber from the determined distances in the implantable medical device.

An implantable medical device comprising a plurality of leads and an implantable medical device circuit enclosed within a hermetically sealed housing comprising:

• a first endocardial lead bearing a first sonomicrometer crystal disposed through a venous pathway into a second heart chamber in association with the septum separating the first heart chamber from the second heart chamber, whereby the first sonomicrometer crystal is oriented toward but outside the first heart chamber;
• a second endocardial lead bearing a second sonomicrometer crystal disposed through a venous pathway into a coronary vessel alongside the first heart chamber whereby the first and second sonomicrometer crystals are arranged in a vector extending through the first heart chamber;
• means operable during one or more heart cycle for periodically energizing one of the first and second sonomicrometer crystals to emit an ultrasonic frequency emitted signal that causes the other of the first and second sonomicrometer crystals to develop an ultrasonic frequency sense signal;
• means for determining the distance between the first and second sonomicrometer crystals as a function of the time delay between emission of the emitted signal and sensing of the respective sense signal;
• and
• means for deriving and storing data representing one or more of contractility and cardiac output of the first heart chamber from the determined distances in the implantable medical device.

Apparatus for determining dimensional changes in the left ventricle due to mechanical movement of the left ventricle during the heart cycle comprising:

• a first endocardial lead bearing a first sonomicrometer crystal disposed through a venous pathway with the first sonomicrometer crystal lodged within the right ventricle separated from the left ventricle by the septal wall;
• a second endocardial lead bearing a second sonomicrometer crystal disposed through a venous pathway through the right atrium and the ostium of the coronary sinus such that the second sonomicrometer crystal is lodged within a coronary vessel in relation to the left ventricle, whereby the first and second sonomicrometer crystals are arranged in a vector through and across a substantial portion of the left ventricle;
• means for periodically energizing one of the first and second sonomicrometer crystals to emit an ultrasonic frequency emitted signal that causes the other of the first and second sonomicrometer crystals to develop an ultrasonic frequency sense signal;
• and
• means for determining the distance between the first and second sonomicrometer crystals as a function of the time delay between emission of the emitted signal and sensing of the respective sense signal, whereby the mechanical motion of the left ventricle over the heart cycle can be determined without entering the left ventricle.

Apparatus for determining dimensional changes of the atria comprising:

• a right ventricular endocardial lead bearing a first sonomicrometer crystal disposed through a venous pathway with the first sonomicrometer crystal lodged within the right ventricle;
• an atrial endocardial lead bearing a second sonomicrometer crystal disposed through a venous pathway with the second sonomicrometer crystal lodged in one of the right atrium or in the coronary sinus adjacent the left atrium, whereby the first and second sonomicrometer crystals are arranged in a vector through the one of the right and left atrium;
• means for periodically energizing one of the first and second sonomicrometer crystals to emit an ultrasonic frequency emitted signal that causes the other of the first and second sonomicrometer crystals to develop an ultrasonic frequency sense signal;
• and
• means for determining the distance between the first and second sonomicrometer crystals as a function of the time delay between emission of the emitted signal and sensing of the respective sense signal, whereby the mechanical motion of the atria can be determined.

Apparatus for pacing the right and left ventricles to alleviate symptoms of heart failure comprising:

• a first lead bearing a first sonomicrometer crystal disposed at a first location of the heart outside the left ventricle;
• a second lead bearing a second sonomicrometer crystal disposed at a second location of the heart outside the left ventricle, whereby the first and second locations define a vector across and through a substantial portion of the left ventricle;
• means for repetitively timing a pacing escape interval establishing paced heart cycles;
• means for delivering a first pacing pulse to one of the right and left ventricles at the time-out of each pacing escape interval and a second pacing pulse to the other of the right and left ventricles separated in time from the first pacing pulse by a pace delay;
• means for periodically energizing one of the first and second sonomicrometer crystals to emit an ultrasonic frequency emitted signal that causes the other of the first and second sonomicrometer crystals to develop an ultrasonic frequency sense signal;
• means for determining the distance between the first and second sonomicrometer crystals as a function of the time delay between emission of the emitted signal and sensing of the respective sense signal, whereby the mechanical motion of the left ventricle over the heart cycle and cardiac output from the left ventricle can be assessed without entering the left ventricle;
• and
• means for adjusting the pace delay to maximize the assessed cardiac output.

Apparatus for pacing the right and left ventricles to alleviate symptoms of heart failure comprising:

• a first endocardial lead bearing a first sonomicrometer crystal and a first pace/sense electrode disposed through a venous pathway with the first sonomicrometer crystal lodged within the right ventricle separated from the left ventricle by the septal wall and the first pace/sense electrode situated for pacing the right ventricle;
• a second endocardial lead bearing a second sonomicrometer crystal and a second pace/sense electrode disposed through a venous pathway through the right atrium and the ostium of the coronary sinus such that the second sonomicrometer crystal is lodged within a coronary vessel in relation to the left ventricle whereby the first and second sonomicrometer crystals are arranged in a vector through and across a substantial portion of the left ventricle and the second pace/sense electrode is situated for pacing the left ventricle;
• means for repetitively timing a pacing escape interval establishing paced heart cycles:
• means for delivering a first pacing pulse through one of the first pace/sense electrode and the second pace/sense electrode at the time-out of each pacing escape interval and a second pacing pulse to the other of the first pace/sense electrode and the second pace/sense electrode separated in time from the first pacing pulse by a pace delay;
• means for periodically energizing one of the first and second sonomicrometer crystals to emit an ultrasonic frequency emitted signal that causes the other of the first and second sonomicrometer crystals to develop an ultrasonic frequency sense signal;
• means for determining the distance between the first and second sonomicrometer crystals as a function of the time delay between emission of the emitted signal and sensing of the respective sense signal, whereby the mechanical motion of the left ventricle over the heart cycle and cardiac output from the left ventricle can be assessed without entering the left ventricle;
• and
• means for adjusting the pace delay to maximize the assessed cardiac output of the left ventricle.

An apparatus for use in providing therapy to a heart, comprising:

• a sensor to measure at least one distance measurement in the heart;
• a delivery circuit coupled to the sensor to deliver a first pacing pulse to a first location in the heart, to deliver a second pacing pulse to a second location in the heart, and to control time of delivery of at least one of the first and second pacing pulses based on the at least one distance measurement, wherein the sensor comprises:
• a first sonomicrometer crystal disposed at a first location of the heart;
• and
• a second sonomicrometer crystal disposed at a second location of the heart, wherein the first and second sonomicrometer crystals are adapted for placement outside the left ventricle such that the first and second locations define a vector across a substantial portion of the left ventricle.

An apparatus for use in providing therapy to a heart, comprising:

• a sensor to measure at least one distance measurement in the heart;
• a delivery circuit coupled to the sensor to deliver a first pacing pulse to a first location in the heart, to deliver a second pacing pulse to a second location in the heart, and to control time of delivery of at least one of the first and second pacing pulses based on the at least one distance measurement, wherein the sensor comprises:
• a first sonomicrometer crystal disposed at a first location of the heart;
• and
• a second sonomicrometer crystal disposed at a second location of the heart, and further comprising:
• means to measure cardiac output of the heart;
• and
• wherein the delivery circuit includes a circuit to adjust the time of delivery of at least one of the first and second pacing pulses to maximize cardiac output.