Abstract: An inflow conduit of a ventricular assist device configured to prevent formation of recirculation and stagnation zones as well as collapse due to external forces or pump induced suction can be rigid and have a funnel like shape with an elbow to accommodate a patient anatomy. Stiffening elements and pressure sensing devices can also be provided associated with the inflow conduit.

Abstract: A blood pump having rotor and/or stator touch down zones to prevent pump failure or hernolysis which can occur if the rotor comes into contact with the stator due to power failure or mechanical shock. The touch down zones can include forming, or coating, portions of adjacent surfaces of the stator and rotor which can come into contact if a rotor touch down occurs. The materials used to form or coat the touch down zones can have properties which ensure that no consequential damage to the contacting surfaces occurs.

Abstract: A blood pump having rotor and/or stator touch down zones to prevent pump failure or hemolysis which can occur if the rotor comes into contact with the stator due to power failure or mechanical shock. The touch down zones can include forming, or coating, portions of adjacent surfaces of the stator and rotor which can come into contact if a rotor touch down occurs. The materials used to form or coat the touch down zones can have properties which ensure that no consequential damage to the contacting surfaces occurs.

Abstract: A method and apparatus as described herein for substantially, but not entirely, blocking back-flow through a blood pump when the blood pump is not pumping blood wherein the method and apparatus can operate passively or actively if the blood pump stops pumping in order to provide a limited back-flow through the blood pump to prevent clot formation.

Abstract: A back flow limiting valve member which substantially, but not entirely, blocks reverse blood flow through a blood pump, such as when the blood pump is not pumping blood or pumping below a predetermined rate. The valve member can operate passively or actively in order to provide a limited back-flow through the blood pump to prevent clot formation. The back flow check valve may also be employed to restrict reverse blood flow through a blood flow conduit or blood vessel rather than in a blood pump.

Abstract: A blood pump having rotor and/or stator touch down zones to prevent pump failure or hemolysis which can occur if the rotor comes into contact with the stator due to power failure or mechanical shock. The touch down zones can include forming, or coating, portions of adjacent surfaces of the stator and rotor which can come into contact if a rotor touch down occurs. The materials used to form or coat the touch down zones can have properties which ensure that no consequential damage to the contacting surfaces occurs.

Abstract: A blood pump for assisting a heart is provided having a stator and a rotor. The rotor is magnetically radially supported creating a suspension gap between the stator and the rotor. The rotor can be supported axially by a Lorentz force bearing and can be magnetically rotated. The stator can have a single or double volute pump chamber and the rotor can have an impeller portion for pumping blood. The rotor can have a center bore as a primary blood flowpath. The suspension gap can be a secondary blood flowpath. The blood pump can also have an axial position controller and a flow rate controller. The axial position controller can cause the axial bearing to adjust the position of the rotor. The flow rate controller can have a member for measuring a dimension of a heart ventricle to control the flow rate to avoid overly distending or contracting the ventricle. A method of operating the flow rate controller to create a pulsatile flow rate is also provided.

Abstract: A blood pump for assisting a heart is provided having a stator and a rotor. The rotor is magnetically radially supported creating a suspension gap between the stator and the rotor. The rotor can be supported axially by a Lorentz force bearing and can be magnetically rotated. The stator can have a single or double volute pump chamber and the rotor can have an impeller portion for pumping blood. The rotor can have a center bore as a primary blood flowpath. The suspension gap can be a secondary blood flowpath. The blood pump can also have an axial position controller and a flow rate controller. The axial position controller can cause the axial bearing to adjust the position of the rotor. The flow rate controller can have a member for measuring a dimension of a heart ventricle to control the flow rate to avoid overly distending or contracting the ventricle. A method of operating the flow rate controller to create a pulsatile flow rate is also provided.

Abstract: A ventricular assist device for a heart includes a compression band-stay-pad assembly for encircling substantially the heart perimeter and comprising an elongated band member or chain disposed in a sealed protective structure filled with a lubricating medium. The band member may be fixed at one end and wound upon, or unwound from, a rotatable spool by a drive motor through a speed reducer. Force-transmitting support or stay assemblies are disposed in the protective structure between the band member and a resilient pad assembly for encircling the heart and promoting heart tissue ingrowth therein. The force-transmitting stay assemblies are biased circumferentially, and thus radially outward, by compression return springs disposed therebetween.

Abstract: A ventricular assist device for a heart includes a compression band-stay-pad assembly for encircling substantially the entire heart perimeter and comprising an elongated band member or chain disposed in a sealed protective structure filled with a lubricating medium. The band member may be fixed at one end and wound upon, or unwound from, a rotatable spool by a drive motor through a speed reducer. Force-transmitting support or stay assemblies are disposed in the protective structure between the band member and a resilient pad assembly for encircling the heart and promoting heart tissue ingrowth therein. The force-transmitting stay assemblies are biased circumferentially, and thus radially outward, by compression return springs disposed therebetween.

Abstract: A ventricular assist device may include a cardiac compression assembly which comprises a gel-filled pad of generally concave configuration, mounted on a pressure plate with peripheral portions of the pad extending beyond the periphery of the plate, to preclude damage to the heart by the peripheral edges of the plate. The gel-filled pad may have undulating opposite sides formed by intersecting rows of raised dimples. The pad also includes portions for suturing the pad to a heart ventricle, and at least some of the dimples on the side of the pad facing the heart ventricle are provided with ventricle tissue growth-promoting islands. An electrode, in the form of a grid having intersecting strips which define dimple-receiving openings therebetween, also may be mounted on the venticle side of the pad. As many as eight circumferentially arranged cardiac compression assemblies, having lower ends pivotally mounted on a support member adapted to be located adjacent the apex of a heart ventricle, may be provided.

Abstract: A device for compressing a ventricle of a heart from one or more sides in synchronism with the natural contraction of the ventricle (systole), and providing arrhythmia control of the heart, is completely implantable in the body of a patient user externally of the heart. Compression of the ventricle is produced by a plurality of spaced compression plate assemblies and a ventricle apex-compression plate, a single compression plate-band assembly or tightenable bands. The compression plate assemblies comprise suitably located electrodes for heart monitoring purposes. A power supply of the implanted device can be recharged transcutaneously, and various other components of the device can be noninvasively programmed and interrogated by external circuits. The compression plate assemblies may be operated by a small brushless DC motor. An implantable manual pump mechanism, for operating the compression plate assemblies, also is provided for emergency purposes.

Abstract: An implantable cardioversion system employing a bipolar electrode for R-wave sensing, the system utilizing heart rate averaging and probability density function techniques in determining whether or not the heart of a patient is to be automatically cardioverted. An improved bipolar electrode facilitates acquisition of a highly accurate R-wave. The implantable system is further provided with the capabilities of (1) providing, upon magnet-type interrogation, an audible indication of proper placement of the bipolar electrode in the body of a patient, (2) providing an audible indication to verify the status of the implanted device (activated or deactivated), (3) the capability of providing, upon request, a transmitted signal modulated with stored information corresponding to the number of times cardioversion of the patient has taken place, (4) the capability of preventing external cardioversion shock from being shunted across the electrodes, and (5) the capability of detecting average heart rate.

Abstract: An implantable heart stimulator and related method calls for the determination of a given heart condition from among a plurality of conditions, the selection of at least one mode of operation for treating the determined condition, and the execution of the mode of operation selected, so as to treat the determined condition. In one embodiment of the invention, wherein a plurality of modes of operation for treating the various conditions are provided, the implantable heart stimulator includes processors, each processor being designed to efficiently execute a respective group of modes of operation. A further embodiment of the present invention calls for the implantable heart stimulator to be implemented by at least one programmable microprocessor. A still further embodiment calls for the provision of a data input/output channel, by means of which data can be provided to and retrieved from the implantable heart stimulator.

Abstract: A heart rate detector apparatus, particularly for use in an implantable defibrillator, is disclosed. The heart rate detector apparatus includes two distinct detector circuits each responsive to ECG waveforms of different characteristics. One of the detector circuits is responsive to ECG waves having slew rates above a predetermined threshold. The other detector circuit is responsive to ECG waves having lower slew rates, such as ECG waves of more sinusoidal shape. A coupling circuit automatically couples one of the two detector circuits to an output circuit, such as a heart rate comparator. In a specific embodiment, the heart rate comparator determines the heart rate, compares the heart rate with a predetermined rate, and, if the heart rate exceeds the predetermined rate for a predetermined time period, provides an output signal. The output signal may be used to enable a defibrillating circuit to deliver a defibrillating shock to the patient.

Abstract: A method and apparatus for effecting automatic ventricular defibrillation and/or demand cardioversion comprises an implanted automatic defibrillator having a normal (ventricular defibrillation) mode of operation and a cardioverting (demand cardioversion) mode of operation. One embodiment of the invention includes a simulated fibrillation source, externally located, for applying a simulated fibrillation signal to the patient via corresponding electrodes, the internal automatic defibrillator detecting the simulated fibrillation signal and responding thereto so as to apply a defibrillating voltage (in the normal mode) or a cardioverting voltage (in the cardioverting mode) to the heart of the patient. Another embodiment of the invention also includes an external command system, by means of which the implanted automatic defibrillator is actuated from the normal mode to the cardioverting mode, to reduce the discharge energy level, to cardiovert in synchronization with the QRS complex, or both.

Abstract: A programmable implantable pacer is provided for performing the dual functions of demand pacing as well as standby tachycardia breakup. A command parameter control is used for programmably controlling parameters of the pacer operation as well as of the tachycardia recognition and response to same. Upon recognition of tachycardia, a series of stimulus pulses of predetermined rate and number are delivered, the tachycardia breakup pulses being generated and delivered through an output circuit utilized commonly with the demand pacer circuitry.

Abstract: A heart pacer employing a digital parameter controlling circuit is controlled by data received from an external source, the data preferably being in the form of magnetic pulses of width corresponding to the desired logic state of the parameter controlling signal. The externally transmitted signal which is received by the pacer comprises both parameter data for controlling selected pacer parameter operation and access data which is processed by the pacer for determining whether the parameter data is accepted for control purposes. The access and parameter data components of the externally generated signal are intermixed so that when receipt of the signal is enabled by the pacer, proper receipt of the parameter data is also ensured.

Abstract: A digital cardiac pacer has an asynchronous interval counter to count clock pulses to establish a stimulation interval at the end of which it produces a pulse for initiating a stimulation pulse. A control counter to which amplified naturally occurring heat pulses or stimulation pulses are applied controls the delivery of a resetting pulse to the asynchronous interval counter to reinitiate its count. If the stimulation, heart, or an interference pulse is detected during the count of a "refractory period," the control counter is reset and the refractory period is extended. If another stimulation, heart, or interference, pulse is detected during the extended refractory period, no resetting pulse is delivered, and the asynchronous interval counter continues its normal count. If during the period of time following the extended refractory period a stimulation, heart, or interference pulse is received, the control counter produces a resetting pulse to reset the asynchronous interval counter.

Abstract: An infant grows rapidly enough that the distance between the heart and the location for the implantation of a cardiac pacer can change during the few years between surgical investigations of the implanted apparatus. The lead connecting the pacer with the heart follows a large spiral path around the pacer so that the spiral can tighten to a smaller spiral to accommodate the greater distance between the heart and the pacer as the infant grows. Such spiral portion of the lead is within a plastic bag permitting such contraction of the spiral without the lead adhering to tissue. The association of the plug at the end of the lead with the cylindrical socket in the end face of the pacer helps to direct the lead toward its initial large spiral path. Such socket is encapsulated in a plastic shield at one of the four corners of the two side faces of the pacer. Adequate battery life is achieved by one or more cells having the combination of a lithium anode and thionyl chloride-containing electrolyte.