Abstract:
An apparatus including a chest strip comprising a plurality of precordial and limb leads for an electrocardiogram (ECG) and an ECG data recorder coupled to the chest strip, wherein the ECG data recorder configured to receive signals from the leads. An apparatus including a chest strip comprising a plurality of precordial leads positioned to correspond with desired lead placement for an electrocardiogram (ECG) and an ECG data recorder; a plurality of limb leads coupled to the chest strip, wherein the ECG data recorder is coupled to plurality of precordial leads and the plurality of limb leads and configured to receive electrocardiogram data generated by the plurality of precordial leads and the plurality of limb leads. A method including coupling a chest strip including precordial leads and a data recorder to a newborn, the data recorder configured to receive electrocardiogram data from the precordial leads; and transmitting electrocardiogram data from the data recorder.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a continuation-in-part of pending U.S. patent application Ser. No. 11/951,083, filed Dec. 5, 2007 which claims the benefit of the earlier filing date of co-pending U.S. Provisional Patent Application No. 60/882,122, filed Dec. 27, 2006, and incorporated herein by reference. 
     
    
     FIELD 
       [0002]    Neonatal electrocardiogram screening. 
       BACKGROUND 
       [0003]    Long QT syndrome (LQTS) is a genetic disease characterized by an abnormally prolonged QT interval in the electrocardiogram (ECG) waveform. LQTS is a leading cause of sudden cardiac death in the young. When infants with undiagnosed LQTS die, their sudden deaths are often labeled as sudden infant death syndrome (SIDS) because no apparent cause of death could be found by autopsy. Using post-mortem genetic analysis, researchers have found that more than 10% of SIDS cases are actually due to undiagnosed LQTS. LQTS can be diagnosed by a routine 12-lead ECG. Once diagnosed, the treatments for LQTS, including beta-blocker therapy and implantable cardioverter defibrillator (ICD), are very effective in preventing cardiac arrhythmia and sudden death. Therefore, some European countries are considering the possibility of introducing neonatal (days 15-25) ECG screening as part of their National Health Services. Among the European countries, Italian Ministry of Health funded an electrocardiogram (ECG) screening program on over 50,000 babies to assess the feasibility and outcomes of a nationwide neonatal ECG screening. The program has been tremendously successful, and such success has generated enthusiasm toward implementation of a nationwide screening program from many European nations and the United States. 
         [0004]    Since the proposed screening ECGs are targeted at two to four weeks of life, the screenings for LQTS proposed will likely have to be done at a pediatrician&#39;s office or at home. Most nurses or nurse&#39;s assistants are not trained to perform newborn ECGs. A regular ECG machine has 10 long cables which often tangle among themselves. When conducting an ECG test, the operator needs to place 10 electrodes (stickers) on the patient and match the cables with each respective electrode on the patient. This process of untangling the cables, placing electrodes, and matching the cables and electrodes takes skill and time. 
         [0005]    Performing an ECG on a newborn is challenging and often takes up to 20 minutes or more. Placing the leads on a newborn is difficult because of limited space on the torso and the babies are not cooperative. Furthermore, performing an ECG on a newborn using the current complicated leads system by inexperienced nurses is prone to error, such as wrong leads placement, artifacts, and inadequate ECG signal acquisition. 
         [0006]    To solve the issues with improper leads placement and tangling of cables, prior inventions have used pre-positioned leads or one-piece design. U.S. Pat. Nos. 4,608,987 and 5,224,479 describe a vest containing pre-positioned leads, which is cumbersome to use in babies and requires a large area of skin contact when worn. Chest strip designs have been proposed by U.S. Pat. Nos. 4,233,987, 5,184,620, and 5,868,671. The limitations of these designs are that they are not designed for use in newborns and infants; and only three to six chest leads are typically provided (e.g., the strips lack limb leads) and therefore cannot be used for QT analysis. U.S. Pat. No. 6,847,836 proposes a one-piece chest pad design for use of ECG monitoring in the emergency room. The chest pad design is not specific for newborns and infants, and has a large skin contact area, which is an important limitation for use in babies because of their sensitive skin. Furthermore, the limb lead positions in the chest pad design of U.S. Pat. No. 6,847,836 are not generally proper for accurate measurement of QT intervals on a 12-lead ECG. As a result, QT analysis using such a design and system is not generally accurate. 
         [0007]    ECG is mostly performed in adults, especially elderly people. ECG on newborns used to be a rare practice. None of the current ECG machine or leads system is designed for use in newborns or infants. As many nations are considering implementing a nationwide newborn ECG screening program, there is an urgent need for a simple, quick and error-proof ECG leads system for newborns. The current design is an ECG leads system specifically designed for newborns to be used in pediatrician&#39;s office, hospital or even at home by parents for newborn screening. 
       SUMMARY 
       [0008]    An ECG system designed for performing newborn ECG is disclosed. In one embodiment, the leads system includes a chest strip which contains precordial leads; retractable limb leads, wireless connector or cable and a leads adaptor. This system with simple, pre-positioned leads allows quick and accurate leads placement for conducting newborn ECG. 
         [0009]    A method of performing an ECG using an ECG leads system is also disclosed. In one embodiment, the method may be used on a newborn infant to detect LQTS and minimize the risk for SIDS. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  illustrates a schematic view of an embodiment of an ECG leads system including a cross-sectional top view of a chest strip, and side views of a receiver and an adapter. 
           [0011]      FIG. 2  shows a side view of the chest strip of  FIG. 1 . 
           [0012]      FIG. 3  shows a schematic side view of two portions of the chest strip of the ECG leads system of  FIG. 1  and shows retractable limb leads partially retracted. 
           [0013]      FIG. 4  shows a schematic top view of a disposable electrode strip suitable for use with the chest strip of the ECG leads system of  FIG. 1 . 
           [0014]      FIG. 5  shows a schematic top view of a disposable electrode lead suitable for use with limb leads of the ECG leads system of  FIG. 1 . 
           [0015]      FIG. 6  shows a schematic view of the ECG leads system recording an ECG of a newborn. 
           [0016]      FIG. 7  shows a schematic side view of another embodiment of an ECG leads system including a chest strip, a cable, and an adapter. 
           [0017]      FIG. 8  shows a schematic top view of another embodiment of an ECG system including a chest strip and a data recorder. 
           [0018]      FIG. 9  shows a block diagram of components of a recorder module suitable for use with a chest strip. 
           [0019]      FIG. 10  shows two modes of operation of an ECG system. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    An ECG leads system for conduction of newborn ECG is described. In one embodiment, this ECG leads system connects directly with an ECG machine. In another embodiment, this ECG leads system includes an adapter that can connect to the cables of an ECG machine to allow the use with existing ECG machines already in hospitals or physician&#39;s offices. 
         [0021]      FIG. 1  illustrates an embodiment of an ECG system. In the illustrated embodiment, ECG system  100  includes the following components: chest strip  110  including a plurality of precordial leads  120  and transceiver  125 ; retractable limb leads  130 ; receiver  160 ; and adapter  170  to connect to an ECG machine. A cross-sectional top view of chest strip  110  is shown to illustrate precordial leads  120  and transceiver  125 . 
         [0022]    In one embodiment, chest strip  110  is designed to embed six precordial leads  120  (V 1 , V 2 , V 3 , V 4 , V 5 , and V 6 ). The chest strip is shaped in a way shown in  FIG. 1  so that when placed on a newborn&#39;s chest, precordial leads  120  (V 1  to V 6 ) will be in proper positions for routine ECG leads placements. As shown in  FIG. 1 , the chest strip will be placed so that V 1  will be in the 4 th  intercostal space (ICS) on the right sternal border, and V 2  will be in the 4 th  ICS on the left sternal border. The 4 th  ICS is at approximately the nipple line which is a convenient landmark for chest strip placement. Indicators for sternum position are shown on the chest strip to assist the operator to position V 1  and V 2  at opposite sides of the sternum. The positions of V 3  to V 6  will also be placed properly and chest strip  110  will be shaped accordingly. V 4  will be at 5 th  ICS in the left mid-clavicular line; V 3  will be half way between V 2  and V 4 ; V 5  will be at the level of V 4  in the left anterior auxiliary line, and V 6  will be at the level of V 4  in the left mid-auxiliary line. Because the chest sizes of newborns at three to five kilograms (kg) body weight do not vary widely, chest strip  110  may be one size that will fit all. In one embodiment, the width of the chest strip is 2 cm and length is 12 cm. In another embodiment, the dimensions are reduced to fit premature infants or infants with smaller chest sizes.  FIG. 6  shows chest strip  110  applied to the chest of a newborn. 
         [0023]    In one embodiment, chest strip  110  is made of nonconductive, flexible material such as plastic, or natural or synthetic fabric.  FIG. 2  shows a side view of an embodiment of chest strip  110 . In this embodiment, chest strip  110  is made of two layers of material (material layer  1105  and material layer  110 ). Chest strip  110  has surface  140  intended to face away from a newborn&#39;s skin when chest strip  110  is applied and surface  150  opposite surface  140  and having leads  150  exposed therethrough. Surface  140  of chest strip  110  is generally smooth with no exposed components. On opposite surface  150  of chest strip  110 , six round shape precordial leads  120 , each representatively 10 millimeters (mm) in diameter, are positioned in V 1 , V 2 , V 3 , V 4 , V 5 , and V 6  locations. Precordial leads  120  are made of a conductive material such as silver. Each of the leads V 1  to V 6  connects to its own wire that connects to transceiver  125  or a cable (see  FIG. 5  and the accompanying text). The wires are electrically insulated from one another so that there will be no interference among the leads. In the embodiment shown in  FIG. 2 , precordial leads  120  may be placed through layer  1110  with wires connected between the leads and transceiver  125 . Layer  1105  lies on the wires and hides the wires in chest strip  110  (e.g., the wires are disposed between layer  1110  and layer  1105 ). 
         [0024]    In one embodiment, ECG system  100  shown in  FIG. 1  and  FIG. 2  includes limb leads  130  connected to chest strip  110 . Right limb leads  130 , RA and RL, are located on the right end of chest strip  110  when the chest strip is applied to a newborn&#39;s chest ( FIG. 1 ). Left limb leads  130 , LA and LL, are located on the left end of chest strip  110  ( FIG. 1 ).  FIG. 6  shows limb leads  130  applied to a newborn 
         [0025]    In one embodiment, a wire extends between each limb lead  130  and transceiver  125 , with a portion of each wire extending through chest strip  110  similar to the wires that connect the precordial leads  130  to transceiver  125 . The wires are electrically insulated from one another and from the wires of precordial leads  120 . As shown in  FIG. 2 , in one embodiment, the wires that connect limb leads  130  to transceiver  125  extend at each end from chest strip  110  into a respective hub  145  (shown illustratively on surface  140  of chest strip  110 ). Each hub  145  includes drum  175  on which, in this example, wire  1300  is wound. Drum  175  is rotatable on axis  180  defined by axle bolt or rivet  185  and bearing  190 . Spring biased roller  195  is connected to wire  1300  interiorly of drum  175  and having a center axis co-axially aligned with axis  180 , the roller functioning to exert a retract force continuously on wire  1300  even when the wire is uncoiled from drum  175  and hub  145 . Wire  1300  is continuously biased toward a storage position in hub  145 . 
         [0026]    The wires connecting to limb leads  130  are self-retractable or are biased toward coiling the wires in respective hubs  145 . A pulling force on a limb lead is required to uncoil a wire for a limb lead. Release of the pulling force returns the wire to a coiled configuration. In this manner, when not placed on a limb of a newborn, the leads are conveniently housed in respective hubs  145  to minimize wires tangling. When in use, after chest strip  110  is properly placed on the newborn, each of limb leads  130  can be pulled out to position in the proper places for the regular limb leads placement ( FIG. 3  and  FIG. 6 ). In one embodiment, the wires for upper limb leads (RA and LA) are five inches when fully uncoiled, and the wires for lower limb leads (RL and LL) are eight inches when fully uncoiled. The lengths of the limb leads wires will allow proper placement of limb leads  130 . In one embodiment, a stop may be included on each wire when a lead is uncoiled and positioned. Such a stop may be as simple as a clip on the wire directly outside hub  145  or more elaborate such as an actuator connected to hub  145  to lock roller  195 . When an ECG recording is finished, the operator will push the actuator to unlock roller  195  and allow a wire to retract back to hub  145  and return the lead into a stored position ( FIG. 2 ). 
         [0027]    Referring to precordial leads  120  and limb leads  130 , in one embodiment, the leads are not placed directly on a newborn&#39;s skin. Instead, disposable electrodes are representatively used to ensure good skin contact and connection with the ECG leads.  FIG. 4  shows a side view of disposable electrode  300  that is in a similar shape of chest strip  110  with six round-shaped ionically conductive hypoallergenic hydrogel adhesives  320  placed in similar positions of the V 1 , V 2 , V 3 , V 4 , V 5  and V 6  leads  120  on chest strip  110  (see  FIG. 1 ). In one embodiment, each adhesive  320  is 16 millimeters (mm) in diameter, with electrically conductive button  325  (e.g., a stainless steel button) in the center on a first surface. A second surface of electrode  300  is covered by a removable plastic cover. Prior to applying chest strip  110  to a newborn&#39;s chest, an operator will place the disposable electrode  300  on the underside of chest strip  110  such that each button  325  in the center of each adhesive  320  is in proper contact with the electrically conductive (e.g., silver) center of leads  120  on the chest strip. Then the operator will remove the thin plastic cover of electrode  300  to expose an adhesive side of each adhesive  320  and apply electrode  300  and chest strip  110  on the newborn&#39;s chest. In one embodiment, the adhesive between electrode  300  and chest strip  110  is hypoallergenic hydrogel. In an embodiment where the adhesive is associated only with adhesive  320  rather than the entire chest strip, the contact with a newborn&#39;s skin is minimized. 
         [0028]      FIG. 5  shows disposable electrode  305  that may be used with the limb leads  130 . Electrode  305  includes round ionically conductive hypoallergenic hydrogel adhesive  330 , 20 mm in diameter, with a conductive (e.g., stainless steel) button  335  in the center on one surface to contact a conductive portion of limb lead  130 . A removable plastic cover may be placed over a second adhesive surface of adhesive  330 . The cover will be removed prior to attaching the electrode on the newborn. In one embodiment, a hypoallergenic hydrogel is provided on the adhesive surface of each electrode  305  that will ensure good skin contact. After chest strip is placed properly on the chest, the operator will pull each individual limb leads out and clip or snap on a respective electrode  330 . 
         [0029]    As noted above, in one embodiment the wires from limb leads  130  (RA, RL, LA, LL) and precordial leads  120  (V 1 , V 2 , V 3 , V 4 , V 5 , V 6 ) run through chest strip  110  individually and connect to transceiver  125 . Transceiver  125  is, for example, a Bluetooth chip located at the left end of chest strip  110 . In one embodiment, transceiver  125  is programmed to receive and transmit ECG signals from limb leads  130  and precordial leads  120 . In the embodiment of ECG system  100  shown in  FIG. 1 , transceiver  125  wirelessly sends ECG signals received from the various leads to receiver  160 , such as a Bluetooth chip. Receiver  160  then distributes the received signals to contact points of adaptor  170  (contact points corresponding to signals for six precordial leads V 1 , V 2 , V 3 , V 4 , V 5 , V 6 , and four limb leads RA, RL, LA, LL). Such signals may be transmitted from adaptor  170  by hard wiring a connection between the contact points and an ECG machine (see  FIG. 6 ). 
         [0030]    In one embodiment, adaptor  170  is designed to make ECG leads system  100  compatible with existing, commercially available ECG machines. In one embodiment, the contact points on adaptor  170  are the same as used on regular ECG electrodes, which allows the leads from commercial ECG machine to clip on or clamp on.  FIG. 6  shows ECG system  100  connected to ECG machine  195  and illustrates an ECG signal displayed on ECG machine  195 . 
         [0031]      FIG. 7  shows another embodiment of an ECG system where the connection between a chest strip and a leads adaptor uses wired cable instead of wireless technology.  FIG. 7  shows chest strip  410  including precordial leads  420  (V 1 , V 2 , V 3 , V 4 , V 5 , V 6 ).  FIG. 7  also shows limb leads  430  (RA, RL, LA, LL) connected by individual wires to chest strip  410 . The wires for precordial leads  420  and limb leads  430  extend into harness  450  which connects to adaptor  470 . The signals at adaptor  470  may then be transferred (e.g., via wires) to an ECG machine. Alternatively, harness  450  may connect limb leads  430  and precordial leads  420  on chest strip  410  directly to an ECG machine without the use of adaptor  470 . The wires inside harness  450  are electrically insulated from one another. A representative length of harness  450  is from one foot up to 12 feet depending on the needs. 
         [0032]      FIG. 8  shows an embodiment of an ECG system shaped for proper positioning of leads on a newborn.  FIG. 8  shows chest strip  510  with leads individually wired into flexible printed circuit board  515  disposed in or on chest strip  510 . 
         [0033]    Chest strip  510  is shaped to conform to the anatomic positions of a newborn for the placement of the six precordial electrodes connected to leads (electrodes) (V 1 , V 2 , V 3 , V 4 , V 5 , and V 6 ). RL electrode is positioned at the left lower corner of the strip (as viewed) to serve as the reference (ground) electrode. In this embodiment, three limb electrodes (RA, LA, LL) are connected to the chest strip by individual wires which run through chest strip  510  with six inches of extra wires outside the strip to connect to electrodes. The electrodes may be similar to electrodes described above (see  FIG. 5 ). When the electrodes are detached from the chest strip, the RA, LA and LL electrodes can each be pulled to its respective anatomic position and still maintain a respective wire connection to the chest strip. 
         [0034]    In this embodiment, chest strip  510  has three anatomic landmarks to assist proper electrode positioning; sternum mark  550  to place V 1  and V 2  electrodes on either side of the sternum, nipple line mark  555  for positioning V 1  and V 2  at the level of the 4 th  intercostal space, and left nipple mark  558  above the V 4  electrode to ensure that the chest strip is of appropriate size for the infant. The weight of 2-4 week old infants can vary, with the majority weighing 3 kg to 5 kg. To make the chest strip appropriate for newborns of various body sizes, the chest strip may be made in different sizes, e.g., one for newborns weighing approximately 2.5 kg to 4 kg and another for newborns weighing over 4 kg. 
         [0035]    An upper or top surface of chest strip  510 , in one embodiment, is covered by smooth fabric material with no exposed components. On the opposite or undersurface of chest strip  510  (intended to be in contact with the skin of a newborn), seven round shape electrodes, each 10 mm in diameter, are positioned in RL, V 1 , V 2 , V 3 , V 4 , V 5 , and V 6  locations. The 10 mm electrodes contact surface is made of hydrogel adhesives. All chest and limb electrodes are connected to leads that are individually wired through chest strip  510  and connect to recorder module  525  on the right end (as viewed). In one embodiment, recorder module  525  is detachable from chest strip  510 . Representatively, the leads in chest strip  510  terminate in a pin connection that mate or otherwise connect with terminals of recorder module  525 . A snap on connector is designed to enable the connection of the wires from the chest strip to the recorder module. In one embodiment, the male connector of the snap on connector is at the chest strip and the female connector is at the recorder module. In one embodiment, the female connector at the recorder module is connected to an analog front end in the recorder module so that the analog signals from the chest strip are directed to the analog front end to be processed and converted to digital signals. 
         [0036]    Referring to  FIG. 9  in one embodiment, recorder module  525  contains two components, analog front end  5210  and digital data recorder  5220 . Representatively, analog front end  5210  includes: preamplifier  5212 , low pass filter  5214 , amplifier  5215 , and high pass amplifier  5216 . The analog front end receives the electrical signals collected from the leads/electrodes in chest strip  510  (e.g., signals from 10 leads/electrodes) and amplifies the signals to a suitable level (in mV) for signal processing. The bandpass filters are used to filter out the noise and select the frequency of interest at, for example, 0.04 Hz˜150 Hz. After ECG signals are amplified and noise-filtered, the analog signals are converted to digital signals by the analog-to-digital converter (ADC)  5218 . 
         [0037]    In one embodiment, analog front end or receiver  5210  utilizes an ADS1298, a fully integrated analog front end chip for 12-lead ECG by Texas Instrument (TI). The ADS1298 has an integrated design on a single chip that is 12 millimeters (mm) by 12 mm by 0.8 mm, suitable to be accommodated on chest strip  510 . ADS1298 is equipped with eight high-resolution, simultaneous sampling ADCs and integrated amplifier. The chip is also capable of digital pace detection and continuous lead-off detection. 
         [0038]    Digital data recorder  5220  of recorder module  525  receives digital signals from analog front end  5210  (e.g., from ADC  5218 ) and, in one embodiment, writes the data on to a flash memory or sends the data to a wireless transmitter. The main components of digital data recorder  5220  include a microcontroller (MCU)  5222 , flash memory  5224 , wireless transmitter  5226 , and a battery (not shown). MCU  5222  will regulate the data flow as well as manage the power. In one embodiment, the battery is a rechargeable Li-Polymer battery that will supply power for the entire detachable ECG Recorder Module. The default data flow function by MCU  5222  is to write the data to the flash memory. A mini-USB port may be placed for accessing the flash memory recording via a USB cable connecting to a processor (e.g., a computer). A user can switch the data to be directed to wireless transmitter  5226 , which will send the data instantly. The transmitted data will be received by a wireless receiver connected to the processor. 
         [0039]    Once chest strip  510  is placed on the infant, the analog front end  5210  will detect and ensure all electrodes have proper skin contact and signals. If there are leads off detected by ADS1298, a red signal light will be on. 12-Lead ECG data can be recorded continuously for many hours, until the flash memory is full, or until the battery power runs out. For the purpose of long QT syndrome screening, continuous ECG recording of 30 minutes typically results in adequate ECG data for reliable analysis. When the user finishes ECG data acquisition, in one embodiment, recorder module  525 , may be detached (removed) from chest strip  510 . In one embodiment, chest strip  510  is designed to be one-time use and will be disposed. The recorder module  525  can be transmitted (e.g., carried, mailed, etc.) by the user to a data center for ECG interpretation and data storage. Once any data on recorder module  525  is delivered to a data center by, for example, connecting recorder module  525  to the processor. Following any transmission, the data is transmitted to a processor at the data center, recorder module  525  may be sterilized, its battery recharged if necessary, and then the module can be attached to a new chest strip to be ready for use on the same or another infant. 
         [0040]      FIG. 10  presents two modes of operation of the ECG systems described with reference to  FIG. 8  and  FIG. 9 . In the first mode (identified by identifier  600 ), upon a baby&#39;s discharge after birth, the parents of the baby receive an ECG system from the hospital. When the baby is two to four weeks of age, the parents perform an ECG according to instructions. Once acquisition of ECG data is complete, the recorder module is detached and transported (e.g., mailed) to a central lab. At the central lab, the ECG data is retrieved and interpreted, and the recorder module is sanitized and recharged for reuse. 
         [0041]    In the second mode of operation (identified by identifier  700 ), the ECG system is available at a pediatrician&#39;s office or other examination room. Representatively, at a baby&#39;s 2-week-old well childcare visit, a nurse places the device on the baby while taking vital signs. ECG data is continuously transmitted to a wireless receiver in the office for 30-60 minutes, until the baby is ready to go home. The wireless receiver can connect to a PC via a USB port, or to a router via an Ethernet port to forward the ECG data via the Internet to a secure server at a central lab. The recorder module will be sanitized at pediatrician&#39;s MD office for reuse on the next baby. 
         [0042]    The ECG system described herein has many advantages over traditional ECG leads and cables. In particular, the ECG system described herein has a simple design that is easy to use, relatively error-proof, and compatible with current ECG machines. The ECG system described herein also minimizes skin contact on newborn thereby decreasing the risk for infection and/or skin reaction. 
         [0043]    In the preceding detailed description, the invention is described with reference to specific exemplary embodiments thereof. It will, however, be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of the invention as set forth in the claims. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense.