Source: https://patents.google.com/patent/US20070197859A1/en
Timestamp: 2019-01-21 00:17:45
Document Index: 679357659

Matched Legal Cases: ['art 10', 'art 200', 'art 212', 'art.\n3', 'art.\n4', 'art.\n7', 'art.\n8', 'art.\n13', 'art.\n18', 'art.\n27', 'art.\n28', 'art.\n31']

US20070197859A1 - Cardiac harness having diagnostic sensors and method of use - Google Patents
Cardiac harness having diagnostic sensors and method of use Download PDF
US20070197859A1
US20070197859A1 US11430638 US43063806A US2007197859A1 US 20070197859 A1 US20070197859 A1 US 20070197859A1 US 11430638 US11430638 US 11430638 US 43063806 A US43063806 A US 43063806A US 2007197859 A1 US2007197859 A1 US 2007197859A1
US11430638
A cardiac harness adapted to fit generally around a least a portion of a heart includes at least one elastic spring member forming an annular portion that is elastically deformable and at least one sensor disposed on the annular portion for providing a sensor signal representative of cardiac function. The cardiac harness applies a compressive force on the heart during diastole and systole. The sensor is configured to take a measurement of impedance across the heart, impedance across a lung, evoked response of the heart, activation patterns of the heart, acceleration of a portion of the heart, position of a portion of the heart relative to an ultrasonic transmitter, pH on the heart's epicardial surface, blood oxygen saturation of a portion of the heart, or position of a portion of the heart relative to a magnetic field generating device. The cardiac harness and sensor are delivered and implanted on the heart by minimally invasive access.
This application is a continuation-in-part of U.S. Ser. No. 10/704,376, filed Nov. 7, 2003, which is herein incorporated by reference in its entirety.
FIG. 43 depicts a cross-sectional view and schematic of a heart with impedance sensors disposed on the epicardium, the impedance sensors coupled to an impedance measuring device and positioned to measure impedance across the left ventricle, the right ventricle, and both the left and right ventricle.
FIG. 44 depicts a heart, cross-sectioned portions of a left and a right lung partially surrounding the heart, and impedance sensors on an annular portion of a cardiac harness, the impedance sensors positioned to measure impedance across the left lung
FIG. 45 depicts an accelerometer attached to dielectric material within a longitudinal wire coil of a cardiac harness and sensor leads extending from the accelerometer.
FIG. 46 depicts a plurality of accelerometers attached to grip pads of a cardiac harness, and sensor leads extending from the accelerometers.
FIG. 47 depicts two sonometric sensors attached to dielectric material within a longitudinal wire coil of a cardiac harness, and two pairs of sensor leads extending from the sonometric sensors through the dielectric material.
FIG. 48 depicts a pH sensor attached to dielectric material disposed between two panels of undulating strands of a cardiac harness, and optic fibers extending from the pH sensor.
FIG. 49 depicts a pH sensor attached to a grip pad of a cardiac harness, and a pair of sensor leads extending from the pH sensor.
FIG. 50 depicts a load-versus-expansion curve defining the circumferential load exerted by a cardiac harness over a superelastic working range of expansion, the circumferential load being a function of expansion of the cardiac harness in response to cardiac cycling.
FIG. 51 depicts a magnetic field generating device, three Hall sensors attached to grip pads of a cardiac harness, and sensor leads extending from the sensors to a processor.
Preferably, however, the cardiac harness and associated electrodes and leads may be delivered through minimally invasive surgical access to the thoracic cavity, as illustrated in FIGS. 27-36, and more specifically as shown in FIG. 30. A delivery device 140 may be delivered into the thoracic cavity 141 between the patient's ribs to gain direct access to the heart 10. Preferably, such a minimally invasive procedure is accomplished on a beating heart, without the use of cardio-pulmonary bypass. Access to the heart can be created with conventional surgical approaches. For example, the pericardium may be opened completely or a small incision can be made in the pericardium (pericardiotomy) to allow the delivery system 140 access to the heart. The delivery system of the disclosed embodiments comprises several components as shown in FIGS. 27-36. As shown in FIG. 27, an introducer tube 142 is configured for low profile access through a patient's ribs. A number of fingers 143 are flexible and have a delivery diameter 144 as shown in FIG. 27, and an expanded diameter 145 as shown in FIG. 29. The delivery diameter is smaller than the expanded diameter. An elastic band 146 expands around the distal end 147 of the fingers and prevents the fingers from over expanding during delivery of the cardiac harness. The distal end of the fingers is the part of the delivery device 140 that is inserted through the patient's ribs to gain direct access to the heart.
Treatment of CHF often involves intracardiac and transthoracic impedance monitoring. An increase in ventricular volume and congestion or fluid buildup in the lungs, occurring either acutely or chronically, can signal a progression to CHF. Bioimpedance is known to decrease with the increased presence of fluid, so increases in ventricular volume, which is accompanied by increased amount of blood in the heart, have been correlated with decreases in intracardiac impedance. Similarly, increases in lung congestion or fluid buildup have also been correlated with decreases in transthoracic impedance. Thus, bioimpedance monitoring can assist in predicting CHF hospitalization thereby allowing appropriate therapeutic intervention to be initiated.
As previously mentioned, sensors on the cardiac harness may be used for impedance measurements. Such sensors, referred to herein as impedance sensors, are operably connected to a current source and an impedance measuring device, such as for example a volt meter. The impedance sensors apply an amount of current to cardiac tissue and measure the voltage potential between two impedance sensors to determine the impedance between the two sensors. Alternatively, supply electrodes, separate from the impedance sensors, may be employed to apply current and impedance sensors may be employed only to measure voltage potentials. The number and location of impedance sensors is a matter of choice. For example impedance sensors may be located on the cardiac harness for selectively measuring impedance across the left ventricle, the right ventricle, both the left and the right ventricles, or other portions of a heart.
Referring now to FIG. 43 there is shown a schematic cross section of a heart 200 having an enlarged right ventricle 202 and a left ventricle 204 separated by a septum 206. Impedance sensors 208A-D are attached to the cardiac harness (not shown to maintain clarity of illustration) such that they are distributed over the epicardium. The impedance sensors may be attached in a manner similar to attachment of the pacing/sensing electrodes 132 of FIGS. 25A-26C, or by other means.
The impedance sensors 208-A-D are integrated directly into the cardiac harness to allow selective impedance measurements across the right ventricle, left ventricle, and both left and right ventricles. By being integrated into the cardiac harness, the sensors are delivered and positioned onto the heart when the cardiac harness is deployed. The impedance sensors are operably connected to an impedance measuring device 209, which also provides current to the impedance sensors. In the embodiment illustrated of FIG. 43, impedance sensor 208A is placed proximate the right ventricle 202, impedance sensor 208B is placed in a posterior position, impedance sensor 208C is placed proximate the left ventricle 204, and impedance sensor 208D is placed in an anterior position. As indicated by arrows 210A and 210B, impedance can be measured across the right ventricle by measuring voltage potentials between impedance sensors 208A and 208B and between impedance sensors 208A and 208D, respectively. Impedance can be measured across the left ventricle by measuring voltage potentials between impedance sensors 208B and 208D, as indicated by arrow 210C. In addition, impedance can be measured across both the left and right ventricles, as indicated by arrow 210D, by measuring voltage potentials between impedance sensors 208A and 208C.
Referring now to FIG. 44 showing a posterior view of the heart and lungs, impedance sensors may also be located on the cardiac harness 211 on a heart 212 for measuring impedance across the left lung 214, right lung 216, or both lungs. The exterior surfaces of a left ventricle 218 and an enlarged right ventricle 220 are shown together with a cutaway view of the left and right lungs partially surrounding the heart. The number and location of impedance sensors for measuring impedance across one or both lungs is a matter of choice. In the illustrated embodiment, three impedance sensors 222 on an annular portion of the cardiac harness are placed proximate the left ventricle and adjacent the left lung 214 in order to measure impedance across the left lung.
The impedance sensors 222 may be integrally attached in a manner similar to attachment of the pacing/sensing electrodes 132 of FIGS. 25A-26C, or by other means. In another embodiment, the impedance sensors are integrally attached with sutures, a biocompatible adhesive, or other means to one or more to panels 21, 61 (see for example FIGS. 5A, 12, and 15A) of undulating strands or elastic spring members of a cardiac harness. For purposes of applying current and measuring voltage potentials across a lung, dielectric material may be used to attach the impedance sensors to the cardiac harness such that conductive surfaces of the impedance sensors face toward the lung and are electrically insulated from surface portions of the heart.
With continued reference to FIG. 44, a remote impedance sensor 224 is disposed on the opposite side of the left lung 214. The remote impedance sensor may be located under or above the skin, and may be associated with a pacemaker (not shown) implanted subcutaneously. Impedance can thus be measured across the impedance sensors 222 on the cardiac harness and the remote impedance sensor 224, as indicated by arrows 226.
Evoked Response Sensor
As previously mentioned, pacing of the heart is achieved by the delivery of a short, intense electrical pulse to the myocardial wall in contact with an electrode 132 (see FIGS. 25A-26C). In one embodiment, the same electrode is used to sense or detect the intrinsic activity of the heart by measuring its evoked response, that is by measuring cardiac potentials evoked by the application of a pacing pulse. In this way, pacing pulses may be modified accordingly in terms of timing, amplitude, or other variables. For example, if any evoked response sensor does not elicit an evoked response, then the pacing amplitude for that electrode can be adjusted upwards and/or a new pacing stimulus can be immediately delivered. Preferably, for improved detection capabilities and to minimize artifacts, that is residual polarization of cardiac tissue surrounding the pacing electrode immediately after a pacing pulse is delivered, the evoked response sensor is constructed from a low polarizing material, such as for example platinum or platinum-iridium alloy.
Multi-Site Sensors for Detecting Activation Patterns
In another embodiment, the cardiac harness can include multi-site sensors for measuring electrical signals from a heart that triggers chambers of the heart to contract. The sensors are distributed at multiple sites across the epicardium and, thus, can be used to detect times of activations during normal and abnormal cardiac rhythms. During normal cardiac rhythms, the relative timings of detected activations are relatively stable. Thus, when a significant deviation from this normal activation pattern is detected by the multi-site sensors, a processor in communication with the sensors may signal that an abnormal rhythm is in progress and appropriate therapeutic actions can be initiated by a pacemaker, defibrillator, or other device operably controlled by the processor. In addition to arrhythmic detection, multi-site sensors may enhance detection of non-arrhythmic changes to the heart, such as for example, ischemic or other insults to the myocardium.
The multi-site sensors may be integrally attached to the cardiac harness so that the sensors are delivered and positioned onto the heart when the cardiac harness is deployed. Attachment may be in a manner similar to attachment of the pacing/sensing electrodes 132 of FIGS. 25A-26C, or by other means. In another embodiment, the multi-site sensors are attached using sutures, biocompatible adhesive, or other means to one or more to panels 21, 61 (see for example FIGS. 5A, 12, and 15A) of undulating strands of a cardiac harness.
Sensors for measuring unidirectional or omnidirectional acceleration, referred to as accelerometers, can provide insights into the mechanical performance of the heart, including, for example, information about contraction synchrony, contraction magnitude and speed, capture verification, contractility index, and rhythm discrimination. Such information has significant diagnostic value and could be used to directly or indirectly modify therapy. For example, information from accelerometers may be used to monitor intrinsic cardiac function to allow pacemakers and similar devices to respond automatically to patient activity and provide a rate response that is specific, sensitive, and proportional to a patient's exercise intensity.
Rather than having an accelerometer at one location, such as in an implantable pacemaker, and rather than suturing accelerometers to the heart and risk injuring the heart, one or a matrix of accelerometers can be attached to a cardiac harness delivered to a heart by minimally invasive means, as previously described. The number and location of accelerometers is a matter of choice. For example, one or more accelerometers may be placed on the lateral free wall of the left ventricle to detect reduced ventricular function. Additional accelerometers may be employed to simultaneously or selectively monitor function at other portions of the heart.
Preferably, miniaturized accelerometers are used to facilitate minimally invasive delivery of a cardiac harness with accelerometers attached to the harness. Suitable miniaturized accelerometers may incorporate Micro-Electro-Mechanical Systems (MEMS) technology, such as described in U.S. Pat. No. 6,179,610 to Toda which is incorporated by reference herein. Piezoelectric crystal accelerometers are also preferable due to their low cost, reliability, and low current drain.
As shown in FIG. 45, one or more accelerometers 226 may be attached to dielectric material 136 in a manner similar to the attachment of the pacing/sensing electrodes 132 illustrated in FIGS. 25A-26C, or by other means. Unlike the pacing/sensing electrodes, however, the accelerometer may be completely encased in the dielectric material. Alternatively, one or more accelerometers may be placed within an inner lumen of one or more coils 72 of the embodiments illustrated in FIGS. 9-14.
In another embodiment, one or more accelerometers are attached to one or more panels 21, 61 (see for example FIGS. 5A, 12, and 15A) of undulating strands of a cardiac harness. As shown in FIG. 46, accelerometers 226 can be attached with sutures, a biocompatible adhesive, or other means to one or more grip pads 67 of the panels 61 that are frictionally engaged with the heart. Leads extend from the accelerometers to a processor 227 configured to analyze signals from the accelerometers.
Sonometric Sensor
Certain changes in cardiac dimension, either acute or chronic, can signal changes in cardiac status, including a detrimental progression of heart failure. Early detection can provide an alert so that appropriate therapeutic intervention can be initiated. Early detection can be accomplished with sonomicrometry, that is the measurement of distances using sound. Transducers made from piezoelectric ceramic material or “crystals” transmit and receive sound energy. Typically, these transducers operate at ultrasound frequencies, such as 1 MHz and higher.
To perform a single distance measurement, one crystal, referred to as an ultrasonic transmitter, will transmit or fire a burst of ultrasound, and a second crystal will receive this ultrasound signal. The ultrasonic transmitter can be disposed on the cardiac harness or remotely from the cardiac harness. The elapsed time from transmission to reception is a direct and linear representation of the physical separation of the crystals. The elapsed time is measured by a digital counter in operational communication with the sensor and ultrasound transmitter. The digital counter, which may be integrated in a processor coupled to the sensor and ultrasound transmitter, is configured to start when the transmitter fires and to stop when a sensor detects an ultrasound wave. As such, sonomicrometry can be used to measure relative positions and, thus, detect changes in size and patterns of movement of portions of the heart through the use of piezoelectric crystals distributed over the heart.
Preferably, crystal transducers for sonomicrometry, referred to herein as sonometric sensors, are between about 0.7 mm to about 2.0 mm to facilitate minimally invasive delivery of a cardiac harness with a matrix of sonometric sensors attached to the harness.
Typically, a plurality of sonometric sensors are distributed on and integrated directly into a cardiac harness and transmit signals to or receive signals from a processor in order to monitor one or more regions of the heart. As shown in FIG. 47, one or more sonometric sensors 228 may be attached to dielectric material 136 in a manner similar to the attachment of the pacing/sensing electrodes 132 illustrated in FIGS. 25A-26C, or by other means. Leads 229 extend through the dielectric material from the sonometric sensors to a processor (not shown) configured to analyze signals from the sonometric sensors. In addition or alternatively, one or more sonometric sensors are attached with sutures, a biocompatible adhesive, or other means to one or more panels 21, 61 (see for example FIGS. 5A, 12, and 15A) of undulating strands of a cardiac harness. The sonometric sensors can be attached to one or more grip pads 67 of the panels 21, 61 that are frictionally engaged with the heart in a manner similar to attachment of the accelerometers 226 of FIG. 46.
Changes in pH or hydrogen ion concentration of the heart and between the pericardium and epicardium can signal acute or chronic metabolic changes, such as acidosis or alkalosis. Changes in pH levels can also signal development of ischemia, especially if the regions of the heart exhibit differences in pH. A cardiac harness with one or more pH sensors would provide the ability to detect acute or chronic metabolic changes and the onset of ischemia.
Generally, sensors or probes for measuring the pH of solutions comprise two electrodes, a reference electrode and a sensing electrode. Typically, the sensing electrode contains a specially designed surface that changes voltage with pH of the solution to which it is in contact. The reference electrode completes the electrical measuring circuit, providing a stable voltage to which the sensing electrode voltage can be compared. Preferably, the sensing and reference electrodes are combined into a common body to form a pH sensor for measuring the pH of surfaces, such as the epicardial surface of a heart.
Other types of pH sensors may be used, such as for example a fiber optic pH sensor suitable for implantation in tissue. As described in U.S. Pat. No. 4,200,110 to Peterson et al., which is incorporated herein by reference, a fiber optic pH sensor includes an ion permeable membrane envelope which encloses the ends of a pair of optical fibers. A pH sensitive dye indicator composition is present within the envelope. The fiber optic pH sensor operates on the concept of optically detecting the change in color of a pH sensitive dye. The fiber optic pH sensor can be a few millimeters long and less than a millimeter wide, which would facilitate minimally invasive delivery with a cardiac harness.
As shown in FIG. 48, a fiber optic pH sensor 230 may be attached to dielectric material 37 disposed between two panels 21 of undulating strands of a cardiac harness. The pH sensor includes an ion permeable membrane envelope 232 having a proximal end that encloses ends of a light source optic fiber 234 and a light sensor optic fiber 236. The optic fibers 234, 236 extend to a light source and a light detector (not shown). A sealing material is employed to seal the distal end of the membrane envelop to retain a pH-indicating dye-containing composition within the membrane envelope. The membrane envelope is placed on an interior side of the cardiac harness that faces the heart such that the membrane envelope is in contact with a surface of the heart.
In another embodiment, one or more pH sensors are attached with sutures, a biocompatible adhesive, or other means to one or more panels 21, 61 (see for example FIGS. 5A, 12, and 15A) of undulating strands of a cardiac harness. As shown in FIG. 49, a pH sensor 238 can be attached to one or more grip pads 67 of the panels 21 that are frictionally engaged with the heart in a manner similar to attachment of the accelerometers 226 of FIG. 46.
One or more sensors for measuring blood oxygen saturation attached to a cardiac harness provides the ability to monitor and diagnose issues related to acute or chronic changes in oxygen saturation in blood circulating in the myocardium. In one embodiment, an oxygen saturation sensor includes a light source or emitter, such as a red-infrared light emitting diode, and a light sensor, such as a photodiode. The light emitter produces light at two wavelengths, 650 nm and 805 nm, for example. The light is partly absorbed by hemoglobin in blood, by amounts which differ depending on whether it is saturated or desaturated with oxygen. The light sensor is positioned such that it collects light reflected by mycodardium underlying the sensor. A processor in communication with the light sensor calculates the absorption at the two wavelengths and computes the proportion of hemoglobin which is oxygenated. In other embodiments, the blood oxygen saturation sensor is configured to emit and detect light at one or more than two wavelengths in order to improve accuracy.
One or more blood oxygen saturation sensors may be attached to dielectric material 136 in a manner similar to the attachment of the pacing/sensing electrodes 132 illustrated in FIGS. 25A-26C, or by other means. In addition or alternatively, one or more blood oxygen saturation sensors are attached to one or more panels 21, 61 (see for example FIGS. 5A, 12, and 15A) of undulating strands of a cardiac harness. The blood oxygen saturation sensors can be attached with sutures, a biocompatible adhesive, or by other means to one or more grip pads 67 of the panels 21, 61 that are frictionally engaged with the heart in a manner similar to attachment of the accelerometers 226 of FIG. 46.
One or more Hall sensors on the cardiac harness may be used to provide information on cardiac motion and position in three-dimensional space. As shown in FIG. 51, a plurality of Hall sensors 246 are attached to a cardiac harness 248 and are distributed over a portion of the heart of a patient. A magnetic field generating device 250 is located outside of the thorax of the patient. The device produces a magnetic field in the space occupied by the Hall sensors. The magnetic field results in a Hall voltage generated in a Hall element, a current-carrying conductor, within each of the Hall sensors. The Hall voltage is proportional to the current in the Hall element and to the strength of the magnetic field at the location occupied by the Hall element. In this way, the Hall voltage provides information on three-dimensional movement and position of the Hall element and, thus, portions of the heart adjacent to the Hall element.
The Hall voltage is usually on the order of microvolts. As such, the Hall sensor 246 may include additional electronics to regulate current to the Hall element and to amplify the Hall voltage from the Hall element. Preferably, the Hall sensor is a single integrated circuit that includes the Hall sensor and its associated electronics. In this way, the physical size of the Hall sensor is minimized so as to allow the sensor to be integral to a cardiac harness suitable for minimally invasive delivery. Leads 252 extend from the Hall sensor to a processor 254 configured to provide current and to analyze the output voltage of the Hall sensor. In another embodiment, the associated electronics are located remotely from the Hall element, such as in the processor.
Referring again to FIG. 51, the Hall sensors 246 can be attached with sutures, a biocompatible adhesive, or by other means to one or more grip pads 67 of the panels 61 that are frictionally engaged with the heart. In an alternative embodiment not shown, one or more Hall sensors may be attached to dielectric material 136 in a manner similar to the attachment of the pacing/sensing electrodes 132 illustrated in FIGS. 25A-26C, or by other means. In any case, the Hall sensors are integrated directly into the cardiac harness 248 so that the Hall sensors are delivered and positioned onto the heart when the cardiac harness is deployed.
Superelasticity and Minimally Invasive Delivery
There are many advantages to minimally invasive delivery of the cardiac harness and associated electrodes, pacing/sensing leads, and/or diagnostic sensors for measuring cardiac function. As previously described, the cardiac harness includes at least one elastic spring member forming an annular portion that is elastically deformable, and preferably made of Nitinol or nickel-titanium alloy having a superelastic working range at internal body temperature.
The annular portion may comprise a plurality of panels 61 supported by longitudinal wire coils 72, each panel including rows of spring members 63, as shown in FIGS. 11, 12 and 46. The superelastic working range of the spring members allows the annular portion to deform reversibly to very high strains, up to 10%, for example, such as when the cardiac harness is compacted into a delivery system 140, 180 (FIGS. 30-34 and 37) adapted for minimally invasive delivery of the cardiac harness and when the cardiac harness is expanded to fit around a portion of the heart.
The cardiac harness is in a compacted orientation having a first radial dimension, typically while housed in a delivery system configured to pass through a space between two adjacent ribs, and is deformable such that it expands over the heart to an implanted orientation having a second radial dimension that is greater than the first radial dimension. In one embodiment, the delivery system includes a dilator tube 150, as previously described in FIG. 28. In this embodiment, the first radial dimension of the compacted orientation is equal to or less than the expanded diameter 145 (FIG. 29) of the fingers 143 of the introducer tube 142.
Referring now to FIG. 50, the annular portion of an implanted cardiac harness is adapted to exert a circumferential load 240 (y-axis) in response circumferential expansion 242 (x-axis) of the cardiac harness. In the illustrated embodiment, the circumferential load is defined by a load-versus-expansion curve 244 that is substantially linear and has the form y=ax+b. In other embodiments the load-versus-expansion curve may not be substantially linear and may, for example, be of the form y=ax2+bx+c. Values for variables a, b and c depend on the configuration of the cardiac harness and are a matter of choice to suit the needs of a patient. Preferably, the load-versus-expansion curve exhibits substantially no temporal hysterisis, that is the load-versus-expansion curve remains substantially unchanged through continuous cardiac cycling.
An annular portion made of a superelastic material is less likely to exhibit failure from mechanical fatigue and temporal hysterisis in which the level of compressive force applied to the heart undesirably decreases over time due to continuous cardiac expansion and contraction cycling. Thus, the cardiac harness of the present invention has a relatively long useful life, thereby reducing or eliminating the need for replacement. In cases where a cardiac harness is made of Nitinol alloy or other superelastic material and has a relatively wide elastic range of expansion, the cardiac harness is capable of providing a compressive force to the heart even after the heart reduces in size due to reverse modeling.
Several sensors for providing signals representative of cardiac function may be delivered together upon implantation of the cardiac harness over the heart's epicardial surface as previously described, eliminating the need to position several sensors one by one. There is also no need to suture or otherwise attach the sensors one by one to the heart because of the aforementioned frictional engagement of the cardiac harness between the heart's epicardial surface and the pericardial sac.
1. A cardiac harness adapted to be fitted generally around at least a portion of a heart, the cardiac harness, comprising:
at least one elastic spring member forming an annular portion that is elastically deformable from a compacted orientation having a first radial dimension to an implanted orientation having a second radial dimension larger than the first radial dimension, the annular portion in the implanted orientation being adapted to exert a circumferential load in response to continuous cardiac cycling, the circumferential load defined by a load-versus-expansion curve that remains substantially unchanged through the continuous cardiac cycling; and
at least one sensor disposed on the annular portion and configured for providing a sensor signal representative of cardiac function.
2. The cardiac harness of claim 1, wherein the at least one sensor is configured and positioned on the annular portion for measuring impedance across the heart.
3. The cardiac harness of claim 1, further comprising:
a current source for producing electrical currents; and
an electrode disposed on the annular portion, the electrode coupled to the current source and adapted for delivering an electrical current across the heart.
4. The cardiac harness of claim 1, wherein the at least one sensor is configured and positioned on the annular portion for measuring impedance across a lung.
5. The cardiac harness of claim 1, further comprising:
a remote electrode disposed remotely from the annular portion, the remote electrode coupled to the current source and adapted for delivering an electrical current across a lung.
6. The cardiac harness of claim 1, wherein the at least one sensor is configured for measuring an evoked response of the heart.
7. The cardiac harness of claim 1, wherein the at least one sensor is configured for detecting activation patterns of the heart.
8. The cardiac harness of claim 1, wherein the at least one sensor comprises an accelerometer configured for measuring acceleration in at least one direction at a portion of the heart adjacent to the at least one sensor.
9. The cardiac harness of claim 1, wherein the at least one sensor comprises a piezo-electric crystal and is configured for measuring position relative to an ultrasonic transmitter of a portion of the heart adjacent to the at least one sensor.
10. The cardiac harness of claim 1, wherein the at least one sensor is configured to detect ultrasound waves, and further comprising a transmitter disposed on the annular portion and configured to fire an ultrasound transmission, and a digital counter in operational communication with the at least one sensor and the transmitter, the digital counter configured to start when the transmitter fires and to stop when the at least one sensor detects an ultrasound wave.
11. The cardiac harness of claim 1, wherein the at least one sensor is configured to detect ultrasound waves, and further comprising a remote transmitter disposed remotely from the annular portion and configured to fire an ultrasound transmission, and a digital counter in operational communication with the at least one sensor and the transmitter, the digital counter configured to start when the transmitter fires and to stop when the at least one sensor detects an ultrasound wave.
12. The cardiac harness of claim 1, wherein the at least one sensor is configured for measuring pH between the epicardial surface of the heart and the pericardial sac of the heart.
13. The cardiac harness of claim 1, wherein the at least one sensor comprises a light emitter and a light detector, both for measuring blood oxygen saturation in myocardium adjacent to the at least one diagnostic sensor.
14. The cardiac harness of claim 1, wherein the at least one sensor comprises a current-carrying conductor adapted to generate a voltage in the presence of an electromagnetic field, the voltage representative of a position of the at least one sensor.
15. The cardiac harness of claim 1, wherein the first radial dimension of the compacted configuration is sized to allow the annular portion to pass through an opening between two ribs adjacent to each other.
16. The cardiac harness of claim 1, wherein the at least one sensor is moveable through an incision in the pericardial sac of the heart when the annular portion is urged from the compacted orientation inside a delivery device housing to the implanted orientation outside the delivery device housing.
17. The cardiac harness of claim 1, wherein the at least one sensor is configured to be covered and held by the pericardial sac of the heart at a fixed point on the epicardial surface of the heart.
18. The cardiac harness of claim 1, wherein the elastic spring member comprises at least one undulating row of wire adapted to exhibit superelasticity when the annular portion is in its implanted orientation.
19. The cardiac harness of claim 1, wherein annular portion comprises undulating rows of wire, the wire comprising a nickel-titanium alloy.
20. A cardiac harness adapted to be fitted generally around at least a portion of a heart, the cardiac harness, comprising:
at least one superelastic annular portion that is elastically deformable from a compacted orientation having a first radial dimension to an implanted orientation having a second radial dimension larger than the first radial dimension, the first radial dimension sized to allow the annular portion to pass through an opening between two ribs adjacent to each other; and
21. The cardiac harness of claim 20, wherein the at least one sensor is configured to take a measurement chosen from the group consisting of impedance across the heart, impedance across a lung, evoked response of the heart, activation patterns of the heart, acceleration of a portion of the heart, position of a portion of the heart relative to an ultrasonic transmitter, pH on the heart's epicardial surface, blood oxygen saturation of a portion of the heart, and position of a portion of the heart relative to a magnetic field generating device.
forming an annular portion with at least one elastic spring member and at least one sensor, the annular portion being elastically deformable from a compacted configuration having a first radial dimension to an implanted orientation having a second radial dimension greater than the first radial dimension, the at least one sensor configured for providing sensor signals representative of cardiac function;
applying a circumferential load from the annular portion in response to continuous cardiac cycling, the circumferential load defined by a load-versus-expansion curve that remains substantially unchanged through the continuous cardiac cycling; and
obtaining a sensor signal representative of cardiac function from the at least one sensor on the annular portion.
23. The method of claim 22, further comprising moving the at least one sensor through an incision in a heart's pericardial sac, including urging the annular portion from the compacted orientation inside a delivery device housing to the implanted orientation outside the delivery device housing.
24. The method of claim 22, wherein obtaining a sensor signal representative of cardiac function from the at least one sensor on the annular portion comprises measuring impedance across the heart, including applying an electrical current from an electrode on the annular portion.
25. The method of claim 22, wherein obtaining a sensor signal representative of cardiac function from the at least one sensor on the annular portion comprises measuring impedance across the lung, including applying an electrical current from a remote electrode disposed remotely from the annular portion
26. The method of claim 22, wherein obtaining a sensor signal representative of cardiac function from the at least one sensor on the annular portion comprises measuring acceleration in at least one direction of a portion of the heart.
27. The method of claim 22, wherein obtaining a sensor signal representative of cardiac function from the at least one sensor on the annular portion comprises taking a sonometric measurement from a portion of the heart.
28. The method of claim 27, wherein taking a sonometric measurement from a portion of the heart comprises:
firing an ultrasound transmission from a transmitter disposed on the annular portion;
starting a digital counter in response to the transmitter firing the ultrasound transmission;
detecting an ultrasound wave at the at the least one sensor on the annular portion; and
stopping the digital counter in response to the at least one sensor detecting the ultrasound wave.
29. The method of claim 27, wherein taking a sonometric measurement from a portion of the heart comprises:
firing an ultrasound transmission from a remote transmitter disposed remotely from the annular portion;
detecting an ultrasound wave at the at least one sensor on the annular portion; and
30. The method of claim 22, wherein obtaining a sensor signal representative of cardiac function from the at least one sensor on the annular portion comprises measuring pH on the pericardial sac of the heart.
31. The method of claim 22, wherein obtaining a sensor signal representative of cardiac function from the at least one sensor on the annular portion comprises:
providing a current to a conductor of the at least one sensor, the conductor adapted to generate a voltage in the presence of a magnetic field;
generating a magnetic field in the space occupied by the conductor; and
measuring voltage from the at least one sensor, the voltage proportional to the strength of the magnetic field at the location occupied by the conductor.
US11430638 2003-11-07 2006-05-09 Cardiac harness having diagnostic sensors and method of use Abandoned US20070197859A1 (en)
CA 2652372 CA2652372A1 (en) 2006-05-09 2007-05-02 Cardiac harness having diagnostic sensors and method of use
PCT/US2007/068068 WO2007133947A3 (en) 2006-05-09 2007-05-02 Cardiac harness having diagnostic sensors and method of use
EP20070761773 EP2023851A2 (en) 2006-05-09 2007-05-02 Cardiac harness having diagnostic sensors and method of use
JP2009510060A JP2009536560A (en) 2006-05-09 2007-05-02 Cardiac harness and methods of use thereof provided with a diagnostic sensor
US20070197859A1 true true US20070197859A1 (en) 2007-08-23
ID=38694601
US11430638 Abandoned US20070197859A1 (en) 2003-11-07 2006-05-09 Cardiac harness having diagnostic sensors and method of use
US (1) US20070197859A1 (en)
EP (1) EP2023851A2 (en)
JP (1) JP2009536560A (en)
CA (1) CA2652372A1 (en)
WO (1) WO2007133947A3 (en)
EP2023851A2 (en) 2009-02-18 application
JP2009536560A (en) 2009-10-15 application
CA2652372A1 (en) 2007-11-22 application
WO2007133947A3 (en) 2008-01-31 application
WO2007133947A2 (en) 2007-11-22 application
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:SCHAER, ALAN;FISHLER, MATTHEW G.;REEL/FRAME:017852/0343