Abstract:
A ventricular assist device for intraventricular placement inside a heart of a mammalian subject includes a pump including a housing having an inlet end, an inlet at the inlet end, and an outlet. The pump further includes a moveable element disposed in the pump housing for pumping blood from the inlet to the outlet. A base member is included as well as a spacer member connected to the pump housing and the base member. The base member is positioned a distance from the inlet end of the pump housing to define a gap therebetween. One or more sensor elements are mounted to at least one from the group consisting of the base member and the housing, the one or more sensor elements being configured to measure one or more blood parameters prevailing within the gap during operation of the pump.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is to and claims priority to U.S. Provisional Patent Application Ser. No. 62/363,927, filed Jul. 19, 2016, entitled VENTRICULAR ASSIST DEVICES AND INTEGRATED SENSORS THEREOF, the entirety of which is incorporated herein by reference. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    n/a 
       TECHNICAL FIELD 
       [0003]    The present invention relates to blood pumps usable as implantable ventricular assist devices and, more particularly, to improved blood pump designs with one or more integrated sensors. 
       BACKGROUND 
       [0004]    In certain diseased states, the heart lacks sufficient pumping capacity to maintain adequate blood flow to the body&#39;s organs and tissues. For example, conditions such as ischemic heart disease and hypertension may leave the heart unable to fill and pump efficiently. This condition, also called congestive heart failure, may lead to serious health complications, including respiratory distress, cardiac asthma, and even death. In fact, congestive heart failure is one of the major causes of death in the Western World. 
         [0005]    This inadequacy of the heart can be alleviated by providing a mechanical pump, also referred to as a ventricular assist device (“VAD”), to supplement the pumping action of the heart. VADs may be used to assist the right ventricle, the left ventricle, or both. For example, a VAD may assist the left ventricle by mechanically pumping oxygenated blood from the left ventricle into the aorta. 
         [0006]    U.S. Pat. No. 7,976,271 and U.S. Publication No. 2014/0100414 (“the 414 Publication”), the disclosures of which are hereby incorporated by reference herein and copies of which are annexed hereto respectively as exhibits A and B, disclose certain centrifugal blood pumps that can be used as ventricular assist devices. When implanted, these and other implantable pumps, typically have an inlet that communicates with a ventricle of a patient and an outlet that communicates with an aorta via a flexible conduit which is disposed external to the heart. A pumping element typically resides outside of the heart and urges oxygenated blood from the ventricle to the aorta. 
         [0007]    U.S. Pat. No. 9,050,418 (“the &#39;418 patent”); U.S. Pat. No. 9,173,984 (“the &#39;984 patent”); U.S. Publication No. 2016/0015878 (“the &#39;878 Publication”), the disclosures of which are hereby incorporated herein by reference and copies of which are annexed hereto as respectively as exhibits C, D and E, disclose certain axial flow blood pumps that can be used as ventricular assist devices. When implanted, these and other implantable pumps, typically have an inlet that communicates with a ventricle of a patient and an outlet that communicates with an aorta via an outflow cannula that extends through the ventricle and into the aorta. A pumping element typically resides within the heart and urges oxygenated blood from the ventricle to the aorta. 
         [0008]    When the above-mentioned pumps and other pumps are implanted and in operation, it is desirable to monitor certain parameters to detect abnormal operating conditions and to determine how a pump affects its surrounding environment. For example, flow information can be obtained directly via an ultrasonic flow sensor or indirectly via a pressure sensor. Such information can be used to provide feedback for control of the pump and to detect a blockage or a situation where the pump outpaces a ventricle&#39;s blood supply leading to a suction condition. Certain existing VADs are fitted with sensors for detecting some of these parameters. However, despite considerable effort devoted to improvements of such VADs, still further improvement would be desirable. 
       SUMMARY 
       [0009]    In one embodiment of the present invention, a ventricular assist device for intraventricular placement inside a heart of a mammalian subject includes a pump including a housing having an inlet end, an inlet at the inlet end, and an outlet. The pump further includes a moveable element disposed in the pump housing for pumping blood from the inlet to the outlet. A base member is included as well as a spacer member connected to the pump housing and the base member. The base member is positioned a distance from the inlet end of the pump housing to define a gap therebetween. One or more sensor elements are mounted to at least one from the group consisting of the base member and the housing, the one or more sensor elements being configured to measure one or more blood parameters prevailing within the gap during operation of the pump. 
         [0010]    In another aspect of this embodiment, the one or more sensor elements include a first sensor element mounted to the pump housing and a second sensor element mounted to the base member. 
         [0011]    In another aspect of this embodiment, the first and second sensor elements are ultrasonic transducers. 
         [0012]    In another aspect of this embodiment, the pump inlet has a major longitudinal axis, and wherein the ultrasonic transducers are disposed on the base member and pump housing, and during use, ultrasonic waves emitted from the ultrasonic transducers and passing between the ultrasonic transducers cross the major longitudinal axis of the inlet. 
         [0013]    In another aspect of this embodiment, the first and second sensor elements include an ultrasonic flow sensor, and wherein the device further includes a third sensor element connected to the base member, the third sensor element being a pressure sensor. 
         [0014]    In another aspect of this embodiment, the one or more sensing elements include an ultrasonic transducer mounted on at least one from the group consisting of the pump housing and the base element, the other one from the group consisting of the pump housing and the base element has a reflective surface disposed across the gap from the ultrasonic transducer. 
         [0015]    In another aspect of this embodiment, the pump inlet has a major longitudinal axis, the ultrasonic transducer and the reflective surface being disposed on the base member and pump housing, and wherein ultrasonic waves emitted from the ultrasonic transducer and passing from the ultrasonic transducer to the reflective surface and back to the transducer will cross the major longitudinal axis of the inlet. 
         [0016]    In another aspect of this embodiment, the one or more sensor elements include a pressure sensor. 
         [0017]    In another aspect of this embodiment, the base member has a first end facing toward the pump housing, the base member having a passageway extending within the base member to an opening at the first end of the base member, and wherein the pressure sensor is disposed in the passageway. 
         [0018]    In another aspect of this embodiment, the pressure sensor is mounted on a plug and the plug is releasably received in the passageway. 
         [0019]    In another embodiment, a ventricular assist device for connection to a heart of a mammalian subject includes a first housing member defining an inlet. A second housing member is coupled to the first housing member and defines an outlet. The first housing member and the second housing member define a flow path extending from the inlet to the outlet. A post extends into the flow path from an inner surface of the second housing thereof and aligned with the inlet. A rotor is sized to be received within the first housing member and the second housing member and defines a bore. The post is received within the bore and the rotor is rotatable about the post to pump blood along the flow path. A sensor is mounted on the post. 
         [0020]    In another aspect of this embodiment, the sensor is a pressure sensor. 
         [0021]    In another aspect of this embodiment, the post includes a cylindrical portion and a conical portion, and the sensor is mounted on at least one from the group consisting of the cylindrical and conical portions. 
         [0022]    In yet another embodiment, a method of assisting the pumping action of a heart of a mammalian subject includes operating a pump of a ventricular assist device to pump blood from a ventricle of a mammalian subject into a gap defined between a pump housing and a base member of the ventricular assist device. A parameter of the blood prevailing in the gap is sensed. 
         [0023]    In another aspect of this embodiment, sensing the parameter prevailing in the gap includes sensing the parameter from one or more sensors mounted to at least one from the group consisting of the pump housing and the base member. 
         [0024]    In another aspect of this embodiment, the sensor is one from the group consisting of a pressure sensor and an ultrasonic flow sensor. 
         [0025]    In another aspect of this embodiment, the parameter is one of from the group consisting of pressure and flow rate. 
         [0026]    In another aspect of this embodiment, the method further includes pumping the blood through an outflow cannula in communication with an outlet of the pump housing. 
         [0027]    In another aspect of this embodiment, the outflow cannula is configured to at least partially extend through an aortic valve of the mammalian subject and the base member is connected to an apex of the heart. 
         [0028]    In another aspect of this embodiment, the base member is connected to the apex of the heart with a sewing ring. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0029]    The features, aspects, and advantages of the present invention will become better understood with regard to the following description, appended paragraphs, and accompanying drawings in which: 
           [0030]      FIG. 1A  is an elevational view of a VAD according to one embodiment of the present disclosure as implanted within a heart which is schematically represented; 
           [0031]      FIG. 1B  is an elevational view of a base member of the VAD of  FIG. 1A ; 
           [0032]      FIG. 1C  is a partial sectional view of the VAD of  FIG. 1A ; 
           [0033]      FIG. 2  is a partial sectional view of a VAD according to another embodiment of the present disclosure; 
           [0034]      FIG. 3  is an exploded view of a pump used in a VAD in accordance with an embodiment of the present disclosure; 
           [0035]      FIG. 4A  is perspective partially transparent view of a pedestal plug according to an embodiment of the present disclosure; 
           [0036]      FIG. 4B  is a perspective view of a sensor module of the pedestal plug of  FIG. 4A ; 
           [0037]      FIG. 4C  is a perspective view of the sensor module of  FIG. 4B  with a diaphragm thereof being removed; and 
           [0038]      FIG. 4D  is perspective view of a pedestal of a VAD according to another embodiment of the present disclosure housing the pedestal plug of  FIG. 4A . 
       
    
    
     DETAILED DESCRIPTION 
       [0039]    Referring now to the drawings in which like reference designators refer to like elements,  FIGS. 1A-1C  depict an intraventricular, axial flow VAD according to an embodiment of the disclosure and designated generally as “10.”. VAD  10  includes a pump  30  comprised of a pump housing  36  and internal components disposed within pump housing  36 . Such internal components, as shown in  FIG. 1C , include a moveable element or impeller  32  and electrical coils  34  for moving movable element  32  within pump housing  36 . Pump housing  36  includes sidewalls  37  that house the internal components and define an inlet  31  at a proximal end thereof and a flow passage extending from an inlet  31  at the proximal end of housing  36  to an outlet  39  at the distal end of housing  36 . A hollow outflow cannula  40  communicates with outlet  39  of pump  30  as defined by pump housing  36  and projects distally therefrom. The outflow cannula  40  has outflow apertures The VAD  10  further includes a base member or pedestal  20 . Base member  20  is adapted to be engaged by a mounting ring  70  mounted to an outside of a heart  100 , as depicted in  FIG. 1A . For example, mounting ring  70  may grip an outer surface  25  of base member  20  or by some other engagement means as is known in the art. A projection  24  extends from base member  20  in a direction transverse to an inlet axis A-A of pump  30  and thus transverse to the proximal and distal directions, which are indicated by the arrow D-P in  FIG. 1C . An electrical cable  26  is connected to base member  20  by means of projection  24 . Electrical cable  26 , when implanted, may communicate transcutaneously with an external power source and controller (not shown), such as via a driveline cable or a transcutaneous energy transfer system (“TET”). Alternatively, electrical cable  26 , when implanted, may communicate with an internal controller (not shown) also implanted within the patient. 
         [0040]    A strut or spacer element  12  mechanically connects base member  20  and pump  30 . Such strut  12  is connected to an inlet end or proximal end of pump housing  36  and an inlet facing end or distal end of base member  20 . Such connection between strut  12 , base member  20  and pump  30  forms a gap  18  between base member  20  and pump  30  through which blood flows prior to entering inlet  31  of pump  30 . Electrical conductors  28  from cable  26  extend through base member  20  and through strut  12  to pump  30 . The foregoing elements can be generally as disclosed in the &#39;418 patent, the &#39;984 patent, and the &#39;878 Publication. 
         [0041]    Base member  20  defines a passageway  22  extending therethrough from its proximal end to its distal end as shown in  FIG. 1B . Passageway  22  is closed by a removable closure or plug  50  inserted into the proximal end of base member  20 . As shown in  FIG. 1C , removable closure  50  can hold a pressure sensor  52  for monitoring pressure and/or determining flow within gap  18 . Pressure sensor  52  may be any pressure sensor adapted for use within the body of a mammalian subject. For example, pressure sensor  52  may be any biocompatible microelectromechanical system (MEMS) configured to sense blood pressure in-vivo. When the removable closure  50  is inserted into passageway  22 , sensor  52  may be positioned at a terminal end of passageway  22  and near the distal end of base member  20 , as best shown in  FIG. 1C . Locating sensor  52  at a terminal end of passageway  22  allows sensor  52  to communicate with blood flowing through gap  18  while eliminating the need for blood to travel down passageway  22  to contact sensor  52  which could lead to blood stagnation and clotting therein. 
         [0042]    Electrical contacts (not shown) may be exposed within passageway  22  and may be electrically connected to electrical conductors  28  of cable  26  ( FIG. 1A ) which extend within base member  20 . Such electrical contacts can physically interface with electrical contacts on an outer surface of removable closure  50  in order to power the pressure sensor and receive signals therefrom. Alternatively, removable closure  50  may include a passive element (not shown), such as a coil, that may provide wireless energy and signal transfer capabilities to the removable closure. 
         [0043]    Additional sensor elements are mounted to VAD  10 . These sensor elements include ultrasonic flow transducers  60   a  and  60   b  which are mounted to pump housing  36  and base member  20 , respectively. Such ultrasonic flow transducers  60   a ,  60   b  may be any flow transducer adapted for use within the body of a mammalian subject. For example, the ultrasonic flow transducers  60   a  and  60   b  can be conventional piezoelectric elements that are adapted to emit ultrasonic waves upon application of an alternating voltage at ultrasonic frequency, and to provide an alternating electrical potential when ultrasonic vibrations impinge on them As depicted in  FIG. 1C , sensor element  60   a  is mounted at or near inlet  31  of pump housing  36  while sensor element  60   b  is mounted within base member  20  so that ultrasonic waves UW from either element  60   a  or  60   b  are received by the other sensor element. In particular, sensor elements  60   a  and  60   b  are disposed at opposite sides of inlet axis A-A which extends proximally from inlet  31  of pump  30  toward base member  20 . Ultrasonic waves UW propagated by one of such sensor elements traverse inlet axis A-A and, consequently, pass through blood flowing into inlet  31  of pump  30  during operation before such waves UW are received by the other sensor element. Sensor elements  60   a  and  60   b  may be electrically connected to conductors  28  of cable  26  which may extend through pump housing  36  and base member  20 , respectively, so as to power elements  60   a  and  60   b  and receive signals therefrom. 
         [0044]    Thus, as described, VAD  10  includes a pressure sensor and ultrasonic flow sensor. This allows inlet flow and pressure conditions to be measured directly and indirectly. In addition, the pressure sensor may be susceptible to drift. However, the redundancy provided by ultrasonic transducers  60   a  and  60   b  allows the pressure sensor to be recalibrated in-vivo based on measurements taken by such transducers. In this regard, transducers  60   a - b  may provide reference data for calculating drift of sensor  52  since ultrasonic transducers tend to be less susceptible to drift. An internal or external controller in communication with sensor  52  and transducers  60   a - b  may compare their respective measurements to determine an offset value of sensor  52  in reference to data from transducers  60   a - b . For example, flow rate data taken from transducers  60   a - b  may be converted by the controller to values of pressure for comparison to pressure measurements taken by sensor  52 . Alternatively, pressure data taken by sensor  52  may be converted by the controller to flow rate values for comparison to flow rate data taken by transducers  60   a - b . Once a threshold level of drift is determined, the controller may adjust the outputs of sensor  52  based on the calculated drift. 
         [0045]    In a method of use, VAD  10  may be transapically implanted into a heart  100  as described in the aforementioned &#39;878 Publication. As implanted, outflow apertures  42  of outflow cannula  40  are positioned within an aorta  104 . In addition, pump  30  and a portion of base member  20  are disposed within a left ventricle  102  as depicted in  FIG. 1A . Base member  20  may be secured to an apex of heart  100  via a mounting ring  70  or some other securement device. Passageway  22 , which may have been temporarily occluded by a balloon catheter during implantation, is closed via removable closure  50  which holds sensor  52  by inserting removable closure  50  into passageway  22  from a proximal end thereof. Securement of removable closure  50  may be achieved by corresponding threading within passageway  22  and on an end of removable closure  50 . When firmly fixed to base member  20 , electrical contacts of base member  20  and removable closure  50  may align and interface to form an electrical connection allowing power to be delivered to sensor  52  and signals to be transmitted therefrom. 
         [0046]    When pump  30  is powered on, the pressure sensor  52  and ultrasonic transducers  60   a  and  60   b  may also be powered on. As blood flows into inlet  31  of pump housing  36  through gap  18 , the pressure of such blood is sensed by sensor  52  which generates a corresponding electric signal indicative of the sensed pressure. 
         [0047]    In addition, either transducer  60   a  or  60   b  is actuated so that ultrasonic waves (UW) are emitted therefrom. These waves UW travel toward the other transducer and have a component of velocity parallel to the direction of blood flow BF entering into inlet  31  from the subject&#39;s ventricle  102  via gap  18 . The receiving transducer converts the ultrasonic waves to an electric signal. Because the path from the emitting transducer to the receiving transducer has a component parallel to the direction of blood flow BF, the time of flight of the ultrasonic waves UW is influenced by the velocity of the blood according to the well-known Doppler effect. This causes the phase of the received ultrasonic waves UW to vary with the blood velocity, and thus with the flow rate. Also, because pump housing  36 , strut  12 , and base member  20  are rigid, the geometry of the system is fixed. As used in this disclosure, the term “rigid” should be understood as meaning that these components do not distort in normal operation of the pump to a degree which would appreciably affect the phase difference between the received and emitted ultrasonic waves. The mathematical relationships used to convert phase difference to flow velocity and to convert flow velocity to flow rate, are well known. The circuits used to measure phase difference are also well known and accordingly are not further described herein. 
         [0048]    The electrical signals as generated by sensor  52  and transducers  60   a - b  may be transmitted to an internal or external controller which may further process the signals and store information derived therefrom for later retrieval or real-time display. Such information may allow a clinician and/or patient to continuously monitor prevailing conditions within gap  18 , such as instantaneous intraventricular pressure and pump inlet flow rate and pressure. 
         [0049]    Other alternative embodiments of the aforementioned devices are contemplated. For example, one embodiment of VAD  10  may only include one of the pressure sensor and the ultrasonic transducers. In another embodiment of VAD  10 , a reflective surface may be provided on pump housing  36  in lieu of transducer  60   a  or on base member  20  in lieu of transducer  60   b . In such embodiment, ultrasonic waves from transducer  60   a  would reflect off of the reflective surface and be transmitted back to the transducer where the waves would be received. 
         [0050]    Referring now to  FIG. 2 , a VAD  200  may similarly include a base member  220 , pump  230 , outflow cannula  240 , and strut  212 . Strut  212  connects base member  220  to pump  230  so as to form a gap  218  therebetween. However, unlike VAD  10 , VAD  200  includes ultrasonic transducers  260   a  and  260   b  mounted to a pump housing  236  and base member  220 , respectively, so that transducers  260   a - b  are disposed on the same side of a pump inlet axis B-B. In this regard, transducer  260   b  may be positioned closer to the inlet axis B-B so that a component of velocity of an ultrasonic waves UW from either transducer  260   a  or  260   b  is transverse to axis B-B and directed either upstream or downstream of blood entering into the gap which itself may have a significant component of velocity transverse to the inlet axis as illustrated by the blood flow arrow BF. The flow of blood passing from the ventricle  102  to inlet  231  of pump  230  will have components of velocity both transverse to the axis B-B and parallel to the axis B-B. Provided that the path of the ultrasound propagating between transducers  260   a - b  has a component parallel to a component of the flow velocity at some point along the path, the time of flight of the ultrasound waves UW will vary with the flow and a flow measurement can be taken by monitoring the time of flight. The angle between the flow direction and the ultrasound path may vary along the path, and the velocity of the blood typically will vary along the path. However, because the time of flight of the ultrasound waves UW is measured over the path as a whole, the observed time of flight represents an average of these effects, and is well-correlated with the total flow into inlet  231  of pump  230 . Further, VAD  200  may or may not include a pressure sensor in base member  220 . Also, as mentioned above, a reflective surface can be provided in lieu of one of transducers  260   a  and  260   b.    
         [0051]    In an even further embodiment, base member  220  may not include a passageway  222 . As such, a pressure sensor, such as sensor  52 , or an ultrasonic transducer, such as transducer  260   b , may be mounted directly to base member  220  so as to be intersected by axis B-B. 
         [0052]      FIG. 3  illustrates a pump  310  of a centrifugal flow VAD according to a further embodiment of the present disclosure. As disclosed in the aforementioned &#39;414 Publication, pump  310  comprises an outer housing that includes a first or upper housing element  320  and a second or lower housing element  330 . Housing elements  320  and  330  are formed from biocompatible rigid materials such as titanium, ceramic, or a combination of same. 
         [0053]    Upper housing  320  includes an inlet  322  end in the form of a cannula defining an inlet opening  324 . Lower housing  330  includes a center-post  332  extending from an internal surface  333  thereof. Center-post  332 , as shown, has a cylindrical portion  334  and a conical end portion  336 . When upper and lower housings  320 ,  330  are assembled, center-post  332  extends into inlet opening  324 , and a flow path extending from inlet opening  324  to an outflow end  312   a - b  is cooperatively defined by the housing elements  320 ,  330 . A pressure sensor  338  is disposed within or on a surface of conical portion  336  so that it is exposed to the blood flow path. Pressure sensor  338  may be alternatively located within a surface of cylindrical portion  334 . Pressure sensor  338  may be a MEMS as described above or some other conventional pressure sensor for in-vivo blood pressure determination. 
         [0054]    A movable element  340 , such as the depicted centrifugal-flow impeller, defines an opening  324  which receives center-post  332  so that the moveable element  340  is disposed about center-post  332  between upper and lower housing elements  320  and  330 . Moveable element  340  is driven by cooperating permanent magnets in moveable element  340  and a coil set  331  within lower housing  330 . When moveable element  340  is disposed about center-post  332 , center-post  332  extends from opening  342  of moveable element  340  so that pressure sensor  338  is exposed within cannula  322 . This allows blood entering into cannula  322  to flow over pressure sensor  338  before being centrifugally propelled toward outflow end  312   a - b  by moveable element  340 . A permanent magnet may be disposed within center post  332  or elsewhere in the upper or lower housings  320 ,  330  to prevent contact of center-post  332  and moveable element  340  during operation. 
         [0055]    Upper and lower housings  320 ,  330  may further define a driveline interface  314   a - b  for connection to an electrical cable which may communicate transcutaneously with an external power source and controller, such as via a driveline cable or a transcutaneous energy transfer system (“TET”). Such interface  314   a - b  is electrically connected to coil set  331  within housing so that power supplied by the electric cable to coil set  331  generates a magnetic field that cooperates with the permanent magnet in movable element  340 , thereby operating moveable element  340 . Driveline interface  314   a - b  may also be electrically connected to pressure sensor  338  on center-post  332  via conductors extending through lower housing  330  and within center post  332 . Such conductors may carry power to pressure sensor  338  and carry information signals from pressure sensor  338  to an external controller. 
         [0056]    In a method of use, pump  310  is implanted in a mammalian subject such that inlet opening  324  communicates with a ventricle of the subject&#39;s heart and so that moveable element  340  is disposed external to the heart. Outflow end  312   a - b  may communicate with a flexible conduit (not shown) which extends to and communicates with the subject&#39;s aorta. When pump  310  is powered on, pressure sensor  338  may also be powered on. As moveable element  340  rotates about center-post  332 , blood is drawn from the ventricle into inlet opening  324  and over pressure sensor  338  prior to reaching moveable element  340 . The pressure measured by pressure sensor  338  is communicated to an external controller for further processing and storage. 
         [0057]    In a further embodiment of pump  310 , in addition to pressure sensor  338  being disposed within center-post, an ultrasonic flow sensor may be disposed within the upper and lower housings along the flow path such as the flow sensor described in the aforementioned &#39;414 Publication. Such flow sensor can be used to recalibrate pressure sensor and provide additional flow measurements. 
         [0058]    In an even further embodiment of pump  310 , a pressure sensor  338 ′ (see  FIG. 3 ) may be disposed within a sidewall of inlet  322  of upper housing  320  in lieu of or in conjunction with sensor  338  being disposed within center-post  332 . In this regard, sensor  338 ′ may be exposed to the blood flowing into the inlet cannula  322  and can detect pressure conditions of blood flowing into inlet  322 . Conductors (not shown) may be disposed within the sidewall of inlet cannula  322  and may interconnect pressure sensor  338 ′ with a driveline cable connected to driveline interface  314   b.    
         [0059]      FIGS. 4A-4D  depicts a pedestal plug  450  according to a further embodiment of the present disclosure. Pedestal plug  450  is similar to plug  50  in that it is securable to a pedestal of a VAD, such as pedestal  420  shown in  FIG. 4D , and is operable to measure blood pressure within a gap between such pedestal  420  and a pump. In this regard, pedestal plug  450  is generally an elongate structure that includes a sensor module  460  at a distal end and a tool engagement portion  452  at a proximal end. Tool engagement portion  452  includes a tool opening  454  that is configured to receive a tool, such as a wrench, driver or the like. Additionally, tool engagement portion  452  may be externally threaded so as to interface with internal threads within pedestal  420  allowing plug  450  to be secured thereto. However, other fixation means known in the art are contemplated. 
         [0060]    Sensor module  460  includes a sensor housing  464  that houses various components therein. Such components may include a substrate  465 , MEMS pressure die  466 , and an ASIC chip  468 . As shown in  FIG. 4C , die  466  and chip  468  are separately connected to substrate  465 . However in some embodiments, die  466  and chip  468  may be provided in an integrated package. A diaphragm  462  covers die  466  and chip  468  at a distal end of housing  464  and acts as a sensing element that interfaces with a patient&#39;s blood. Diaphragm  462  communicates with die  466  so that pressure detected by diaphragm  462  is converted to electrical signals which may be communicated to an internal or external controller. 
         [0061]    Conductive bands  456  are disposed between sensor module  460  and engagement portion  452 , as best shown in  FIG. 4A . Such bands  456  are electrically connected to conductors  458  which extend through a proximal end of sensor module housing  464  and are electrically connected to die  466  and chip  468  via substrate  465 . Conductive bands  456 , tool engagement portion  452 , and sensor module  460  may be connected into a single integrated structure by filler material, such as a biocompatible, insulating polymer that joins each of these components together. In this regard, outer surfaces of the conductive bands  456  are preferably exposed. 
         [0062]      FIG. 4D  depicts plug  450  secured to a pedestal  420 . Pedestal  420  is similar to pedestal  20  in that it is connected to a pump, such as pump  30 , via a strut  412 . In addition, pedestal  420  is electrically connected to a cable  426  and includes a passageway configured to receive plug  450 . The passageway may include electrical contacts (not shown) that interface with the exposed outer surfaces of conductive bands  456  when plug  450  is disposed therein so as to help provide power to plug  450 . In this regard, plug  450  may be secured to pedestal  420  by rotating plug  450  with a tool so that threads of plug  450  and pedestal  420  engage. Conductive bands  456 , which provide plug with a 360 degree conductive perimeter, helps ensure that plug is electrically connected to pedestal regardless of the angular orientation of plug  450  after being secured to pedestal  420  via threaded engagement. Once plug is secured to pedestal, diaphragm  462  may be positioned at a terminal end of the passageway of pedestal  420  so as to be capable of measuring blood pressure within a gap between pedestal  420  and a blood pump. 
         [0063]    Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention.