Ultrasound cardiac stimulator

• US 20060052695A1
• Filed: 02/19/2003
• Published: 03/09/2006
• Est. Priority Date: 02/21/2002
• Status: Active Grant

• Current Assignee: TECHNION RESEARCH AND DEVELOPMENT FOUNDATION, LTD.
• Original Assignee: TECHNION RESEARCH AND DEVELOPMENT FOUNDATION, LTD.
• Inventors: Adam, Dan
• Granted Patent: US 7,699,778 B2
• Time in Patent Office: Days
• US Class Current: 600/437
• CPC Class Codes: A61B 2017/00243 cardiac
• CPC Class Codes: A61B 2017/00703 correcting for movement of heart, e.g. ECG-triggered
• CPC Class Codes: A61N 1/3629 in combination with non-electric therapy
• CPC Class Codes: A61N 2007/0078 with multiple treatment transducers
• CPC Class Codes: A61N 7/00 Ultrasound therapy lithotripsy A61B17/22, A61B17/225; massage using supersonic vibration A61H23/00 ; using ultrasound for introducing media into the body A61M37/0092

Abstract

An ultrasound cardiac stimulation system comprising: a spatially selective ultrasound source comprising at least one ultrasound transducer located outside the circulatory system; and a controller; where the controller generates an electrical response in the heart by directing the ultrasound source to transmit a high enough power level of ultrasound to one or more locations in the heart.

Claims

1. An ultrasound cardiac stimulation system comprising:

a spatially selective ultrasound source comprising at least one ultrasound transducer located outside the circulatory system; and

a controller;

wherein the controller generates an electrical response in the heart by directing the ultrasound source to transmit a high enough power level of ultrasound to one or more locations in the heart.

2. A system according to claim 1 and including an injector which injects cardiac drugs into the bloodstream, wherein the controller changes the rate at which cardiac tissue absorbs the drugs by directing the ultrasound source to transmit a high enough power level of ultrasound to one or more locations in the heart.

3. A system according to claim 1, wherein the controller is operative to choose the ultrasound power level.

122. A system according to claim 3, wherein the system has sufficient precision to control the ultrasound power level supplied to cardiac tissue to within ±

10%.

123. A system according to claim 122, wherein the system has sufficient precision to control the ultrasound power level supplied to cardiac tissue to within ±

3%.

124. A system according to claim 3, and including an injector which injects one or both of drugs for treating the heart and contrast agents into the bloodstream.

125. A system according to claim 124 wherein the injector injects drugs into the bloodstream, and the controller changes the rate at which cardiac tissue absorbs the drugs by directing the ultrasound source to transmit a high enough power level of ultrasound to one or more locations in the heart.

126. A system according to claim 1, wherein the controller is operative to choose the one or more locations to which the ultrasound is transmitted.

127. A system according to claim 126, wherein the controller controls the ultrasound source to direct ultrasound energy to a designated location, and the point of highest power flux density falls within an axial precision of 3 mm of said designated location.

128. A system according to claim 127, wherein the point of highest power flux density remains within the axial precision of the designated location for at least 1 millisecond.

129. A system according to claim 126, wherein the controller controls the ultrasound source to direct ultrasound energy to a designated location, and the point of highest power flux density falls within a transverse precision of 1 mm of said designated location.

130. A system according to claim 129, wherein the point of highest power flux density remains within the transverse precision of the designated location for at least 1 millisecond.

131. A system according to claim 126, wherein the controller controls the ultrasound source to direct a high enough power level of ultrasound to one or more locations in the heart to kill cardiac tissue by heating it.

132. A system according to claim 126, wherein the controller controls the ultrasound source to direct a high enough power level of ultrasound to one or more locations in the heart to kill cardiac tissue by cavitation.

133. A system according to claim 1, and including an electrocardiograph which measures the timing of the cardiac cycle.

134. A system according to claim 133, wherein the electrocardiograph is operative to distinguish the electrical response to the ultrasound, originating at any location in the heart, from the electrical response originating one centimeter away from said location.

135. A system according to claim 133, wherein the controller coordinates the timing of the transmission of ultrasound with the cardiac cycle.

136. A system according to claim 133, and including a cardiac catheter which generates an electrical response in the heart, and a calibration mode of the controller, wherein the controller, when it is in the calibration mode, calibrates the ultrasound power transmitted to the heart by the ultrasound array, by comparing a physiological response induced by the ultrasound array to a physiological response induced by the catheter.

137. A system according to claim 136 wherein the physiological responses compared by the controller comprise electrical responses.

138. A system according to claim 136, wherein the physiological responses compared by the controller comprise mechanical responses.

139. A system according to claim 136, wherein the cardiac catheter generates an electrical response by direct electric stimulation.

140. A system according to claim 136, wherein the cardiac catheter comprises an internal ultrasound transducer, and the cardiac catheter generates an electrical response by transmitting ultrasound.

141. A system according to claim 136, wherein the cardiac catheter kills cardiac tissue.

142. A system according to claim 141, and including a laser, wherein the cardiac catheter comprises a light guide, and the light guide carries light from the laser, which light kills cardiac tissue.

143. A system according to claim 133, which uses feedback from the electrocardiograph to control the ultrasound power level.

144. A system according to claim 133, wherein the controller is operative to make a map of the heart, showing the ultrasound power flux required to generate the electrical response at each of several locations in the heart.

145. A system according to claim 133, wherein the controller is operative to direct the ultrasound source to transmit a first sequence of timed localized pulses of ultrasound energy to the heart, and a second such sequence which differs from the first sequence in one or both of timing and location of the pulses, and the controller is operative to collect a first data set showing the effects of the first sequence on the heart, and a second data set showing the effects of the second sequence on the heart.

146. A system according to claim 145, and including a cardiac imaging system, and an image analyzer which analyzes images produced by the cardiac imaging system for the first sequence and the second sequence, and calculates one or more of the systolic left ventricular volume for the first and second sequence, the diastolic left ventricular volume for the first and second sequence, and the ejection fraction for the first and second sequence.

147. A system according to claim 1, and including a cardiac imaging system which produces images showing the position of one or more locations on the heart.

148. A system according to claim 147, and including sensors which determine the relative position and orientation of the imaging system and the ultrasound source.

149. A system according to claim 147, wherein the imaging system determines the relative position and orientation of the ultrasound source by imaging it.

150. A system according to claim 147, wherein the controller coordinates the timing of the imaging system with the timing of the ultrasound source.

151. A system according to claim 147, wherein the imaging system uses ultrasound imaging.

152. A system according to claim 151, wherein the imaging system shares one or more ultrasound transducers with the ultrasound source used to generate the electric response in the heart.

153. A system according to claim 147, and including image processing software which analyzes the images to determine the position of one or more locations on the heart.

154. A system according to claim 153, wherein the image processing software determines the position of one or more locations on the heart in real time during a cardiac cycle.

155. A system according to claim 147 wherein the controller is operative to make a map of the heart, using data from the imaging system, showing the mechanical response of the heart at one or more locations to ultrasound energy transmitted to one or more locations.

156. A system according to claim 147, which uses feedback from the imaging system to control the ultrasound power level.

157. A system according to claim 1, wherein the ultrasound source comprises a phased array of the ultrasound transducers.

158. A system according to claim 1, wherein at least one of the at least one ultrasound transducers is adapted for use on the surface of the body.

159. A system according to claim 158, wherein the at least one ultrasound transducers comprise at least two ultrasound transducers, sized and spaced so that they can be placed between the ribs, in such a way as to avoid blocking of ultrasound by the ribs.

160. A system according to claim 1, wherein at least one of the at least one ultrasound transducers is adapted for use in the esophagus.

161. A system according to claim 1, wherein the ultrasound source and the controller are operative to direct the ultrasound energy with 90% of the power flux falling within 3 mm transversely of the point of highest power flux density.

162. A system according to claim 161, wherein the ultrasound source and the controller are operative to direct the ultrasound energy with 90% of the power flux falling within 1 mm transversely of the point of highest power flux density.

163. A system according to claim 1, wherein the ultrasound source and the controller are operative to direct the ultrasound energy with the power flux spreading out to 50% of its highest density within 6 mm axially of the point of highest power flux density.

164. A system according to claim 163, wherein the ultrasound source and the controller are operative to direct the ultrasound energy with the power flux spreading out to 50% of its highest density within 1.5 mm axially of the point of highest power flux density.

165. A system according to claim 1, wherein the ultrasound source and the controller are operative to direct the ultrasound energy with a power flux density greater than 30 watts per square centimeter at the point of highest power flux density.

166. A system according to claim 165, wherein the ultrasound source and the controller are operative to direct the ultrasound energy with a power flux density greater than 100 watts per square centimeter at the point of highest power flux density.

167. A system according to claim 166, wherein the ultrasound source and the controller are operative to direct the ultrasound energy with a power flux density greater than 300 watts per square centimeter at the point of highest power flux density.

168. A system according to claim 1, wherein the ultrasound source and the controller are operative to direct the ultrasound energy in a pulse lasting less than 10 milliseconds.

169. A system according to claim 168, wherein the ultrasound source and the controller are operative to direct the ultrasound energy in a pulse lasting less than 1 millisecond.

170. A system according to claim 1, wherein the ultrasound source and the controller are operative to direct the ultrasound energy in a pulse lasting for a duration within 10% of a duration for which the controller is directed to direct the energy.

171. A system according to claim 1, wherein the ultrasound source and the controller are operative to direct the ultrasound energy at a frequency greater than 0.5 megahertz and less than 6 megahertz.

4-121. -121. (canceled)

172. A method of changing a cardiac stimulation sequence for a patient, comprising:

a) choosing a test sequence of locations in the heart of the patient, and a time in the cardiac cycle to stimulate each location;

b) stimulating the test sequence of locations at the chosen times in the cardiac cycle, using an ultrasound cardiac stimulation system from outside the heart;

c) evaluating a change in cardiac synchronization of the patient associated with the test sequence;

d) choosing a stimulation sequence for a pacemaker, based at least partly on the change in cardiac synchronization that the test sequence produces; and

e) changing a stimulation sequence of the heart to conform to the chosen stimulation sequence.

173. A method according to claim 172, wherein using an ultrasound cardiac stimulation system from outside the heart comprises using an ultrasound stimulation system from outside the body.

174. A method according to claim 172, wherein changing a stimulation sequence of the heart comprises installing a pacemaker.

175. A method according to claim 172, wherein changing a stimulation sequence of the heart comprises adjusting a pacemaker to obtain improved cardiac synchronization.

176. A method according to claim 172, wherein (a), (b) and (c) are performed a plurality of times for different test sequences, and choosing an optimal stimulation sequence is based at least partly on the change in a measure of cardiac performance that the different test sequences produce.

177. A method according to claim 176, wherein the measure of cardiac performance comprises cardiac output.

178. A method according to claim 176, wherein evaluating the change in the measure of cardiac performance comprises using systolic pressure measurements.

179. A method according to claim 176, wherein evaluating the change in the measure of cardiac performance comprises using images of a mechanical response of the heart to the stimulation.

180. A method according to claim 176, wherein at least one of the test sequences comprises a plurality of locations with the same chosen time.

181. A method according to claim 172, wherein evaluating the change in cardiac synchronization comprises using electrocardiograph data.