Surgery: light – thermal – and electrical application – Light – thermal – and electrical application – Electrical therapeutic systems
Reexamination Certificate
1999-05-26
2001-09-04
Layno, Carl (Department: 3762)
Surgery: light, thermal, and electrical application
Light, thermal, and electrical application
Electrical therapeutic systems
C607S005000, C607S014000, C607S015000
Reexamination Certificate
active
06285906
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to invasive devices and methods for treatment of the heart, and specifically to devices and methods for controlling contraction of the heart muscle.
BACKGROUND OF THE INVENTION
The human body normally regulates the cardiac output in response to body needs by changing the heart rate, as during physical exercise, and/or by adapting the stroke volume. Under pathological conditions, however, some of the normal regulatory mechanisms may be damaged. For example, heart tissue damaged due to myocardial infarct typically cannot sustain normal pumping function. Although such damage is local in its direct effect on the heart tissue, it can lead to an overall reduction in stroke volume, and hence of cardiac output. The body may react to such a reduction by increasing the heart rate, thus imposing long term strain on the heart muscles, leading in more severe cases to heart failure. There is thus a need for devices and treatments that can regulate the activity of local areas of the heart, so as to compensate for the deficiencies in the normal regulation mechanisms and aid in recovery from infarct and other damaging conditions,
PCT patent application PCT/IL97/00012, and the corresponding U.S. national phase application Ser. No. 09/101,723, which are assigned to the assignee of the present patent application and are incorporated herein by reference, describe methods for modifying the force of contraction of at least a portion of a heart chamber by applying a non-excitatory electrical signal to the heart at a delay after electrical activation of the portion. The signal may be applied in combination with a pacemaker or defibrillator, which also applies an excitatory signal (i.e., pacing or defibrillation pulses) to the heart muscle.
PCT patent application PCT/IL97/00236 and the corresponding U.S. national phase application Ser. No. 09/254,900, which are assigned to the assignee of the present patent application and are incorporated herein by reference, describe a pacemaker that modifies cardiac output. This pacemaker applies both excitatory (pacing) and non-excitatory electrical signals to the heart. By applying non-excitatory signals of suitable strength, appropriately timed with respect to the heart's electrical activation, the contraction of selected segments of the heart muscle can be increased or decreased.
PCT patent application PCT/IL97/00233 and the corresponding U.S. national phase application Ser. No. 09/254,903, which are assigned to the assignee of the present patent application and are incorporated herein by reference, describe methods of applying signals to cardiac tissue in order to modify the behavior thereof.
PCT patent application PCT/IL97/00235, which is incorporated herein by reference, describes a cardiac output controller which applies non-excitatory pulses to the heart in order to increase the heart's stroke volume. Typically, the pulses are timed with respect to the heart's natural activity, and are delivered, for example, during a specific time period of each heart beat.
SUMMARY OF THE INVENTION
It is an object of some aspects of the present invention to provide improved methods and apparatus for regulating contraction of heart muscle.
It is a further object of some aspects of the present invention to provide methods and apparatus for control and enhancement of the contraction of local areas of the heart muscle.
It is yet a further object of some aspects of the present invention to provide improved methods and apparatus for increasing heart output.
In preferred embodiments of the present invention, an electrical cardiac stimulator applies electrical energy to a segment of a patient's heart in successive high and low phases, so that in the low phase, an activity level of the segment increases substantially above an intrinsic activity level thereof. The stimulator comprises one or more electrodes, preferably placed at multiple sites in or on the heart, and a control unit. The energy is applied to the heart via the electrodes at a certain amplitude in the high phase, followed by lower-amplitude or substantially no energy applied during the low phase. Preferably, the patient's overall cardiac output increases responsive to the increase of the segment's activity.
In some preferred embodiments of the present invention, energy is applied to more than one segment, preferably in a coordinated fashion, in order to increase cardiac output. It will be appreciated that, although most preferred embodiments of the present invention are described herein with respect to applying energy to one segment, it is within the scope of the present invention to apply the energy to a plurality of segments.
Preferably, the average power output of muscle tissue exposed to repeated applications of electrical energy, as provided by preferred embodiments of the present invention, is greater than that generated responsive to either standard pacing pulses or natural cardiac activity in an in vivo heart. Thus, application of the energy is appropriate, for example, for assisting a heart that is otherwise unable to satisfy immediate physiological requirements of flow rate and blood pressure. In particular, the energy may be applied to one or more segments of the heart, either in a generally-localized region, which may be a functional or a dysfunctional area of one chamber, or in multiple chambers of the heart. Energy applied to each segment is preferably timed with respect to that applied to the other segments so that during a time period when some segments are exposed to the high phase of the energy, and thus do not contribute substantially to the heart's pumping action, the rest of the heart muscle is generally either contracting normally, or in an enhanced manner responsive to application of the low-phase of the energy.
In some preferred embodiments of the present invention, the control unit administers the electrical energy in the form of “contractility control” signals to at least one of the electrodes. Preferably, the high phase has the general form of rapid pacing pulses and/or “fencing” signals, as described in the above-cited U.S. patent application Ser. No. 09/254,903. Fencing signals, applied through one or more electrodes in a vicinity of the segment, typically alter electrical activity and/or a contraction force of the segment by inhibiting the generation and propagation of an action potential in the segment.
In some of these embodiments, throughout the duration of the high phase, the contraction force generated by muscle of the segment may be significantly reduced. The transition from the high to the low phase engenders a large increase in the contraction force, to a level which is typically significantly higher than prior to application of the high phase. In general, the overall force, integrated over a single high phase and the subsequent low phase, is higher than that which would be attained without the application of the contractility control signals. Repeated application of the contractility control signals, i.e., cycling between the high and low phases, preferably yields an overall increase in cardiac output and/or blood pressure responsive to the behavior of the segment (or of a plurality of stimulated segments) during the low phase.
In some preferred embodiments of the present invention, the electrodes are placed at multiple sites on the epicardium and/or endocardium of the segment of the heart, and optionally on other areas of the heart. Alternatively or additionally, one or more of the electrodes are inserted through a catheter into a blood vessel of or in a vicinity of the heart, and apply energy through the vessel wall to a region of the heart. Further alternatively or additionally, at least one of the electrodes is placed elsewhere in or on the patient's body. Typically, each electrode conveys a particular waveform to the heart, which may differ in certain aspects from the waveforms applied to other electrodes. The particular waveform to be applied to each electrode is preferabl
Ben-Haim Shlomo
Darvish Nissim
Felzen Bella
Mika Yuval
Rousso Benny
Cowan Liebowitz & Latman P.C.
Dippert William H.
Impulse Dynamics N. V.
Layno Carl
LandOfFree
Muscle contraction assist device does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Muscle contraction assist device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Muscle contraction assist device will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2485207