Abstract:
A self-contained, hand-held electronic stethoscope including built-in chestpiece, speaker and visual monitor, includes a memory containing prerecorded heart and lung sounds along with a brief description of the malady producing the sounds so that the technician may compare the actual sounds with the prerecorded sounds and observe a suggested diagnosis on the monitor.

Description:
This invention relates to electronic stethoscopes and in particular to a stethoscope in which the output may be compared both by sound and visually on a scope with various sound signals prerecorded on a memory medium. 
     BACKGROUND OF THE INVENTION 
     Various pathological conditions of a patient are revealed by auscultation examination. A normal heart and lungs produce normal sounds which are detected by the stethoscope, and if any abnormalities are detected proper corrective steps may be taken Therefore, it is extremely important for a medical diagnostician to recognize and understand normal and abnormal heart and lung sounds. 
     There are many heart sounds that must be learned by the diagnostician. The human heart has four chambers. During the diastolic or relaxed period, blood flows through the tricuspid valve into the right ventricle and oxygenized blood flows through the mitral valve into the left ventricle. At the end of this very short diastolic period the mitral valve closes followed by the tricuspid valve and the heart muscle contracts in systole while blood is pumped from the right ventricle through the pulmonary valve and blood is pumped from the left ventricle through the aortic valve. There is a sound, called S 1 , that occurs at the closure of the mitral and tricuspid valves and a sound, S 2 , that occurs at the closure of the aortic and pulmonary valves. 
     With the presence of heart disease the individual sounds are often split and may be heard as two sounds on each of the two basic S 1  and S 2  sounds. And in addition to the basic sounds, there are pathologic sounds which may be caused by blood passing through a tight valve or a pathologically enlarged valve opening. And certain disease processes may cause rubbing sounds produced by rubbing of the heart wall on the tissue covering that surrounds the heart. Certain diseases can change or vary the heart sounds. For example, if S 1  appears to be louder than S 2 , it suggests a tightening of the mitral valve or mitral stenosis, whereas an unusually soft S 2  suggests mitral regurgitation. Heart disease is suggested if any component separation occurs during expiration, if separation seems excessive, or if one component is persistently missing. 
     Lung sounds also have two components, that produced by inspiration and that by expiration. With a presence of disease in the lungs the normal lung sounds are disrupted and certain pathologic crackles, rates and wheeze sounds are produced which, in most instances, would point to a certain disease going on in the patient&#39;s pulmonary and even systemic system. 
     The foregoing material discusses only a small fraction of the various sounds that may be detected with a stethoscope. There is a multitude of murmurs, hums and clicks that may be heard at various body locations while in various positions. It is thus apparent that the science of auscultation is difficult and that certain medical technicians, such as ambulance technicians or student who may not have thoroughly mastered the science, would benefit greatly from a stethoscope that included a diagnostic capability. 
     Briefly described, this invention is for a self-contained electronic stethoscope in a housing that includes a prerecorded record of typical sounds, a recorded image of the external pulse recordings of the sound and a suggested diagnosis. The electronic stethoscope normally outputs into a small speaker and to a small oscilloscope for viewing the signal, and depressing a momentary contact switch will divert the prerecorded record output to the speaker and scope for comparison with the stethoscope sounds 
    
    
     DESCRIPTION OF THE DRAWINGS 
     In the drawings which illustrate the preferred embodiment of the invention. 
     FIG. 1 is a schematic drawing of the electronic stethoscope with diagnostic capability; 
     FIG. 2 is a perspective view of the stethoscope housing; and 
     FIG. 3 is a top plan view thereof. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The invention is for an electronic stethoscope that has the capability of diagnosing physical problems by providing a means for comparing a stethoscope sound and oscilloscope image with a typical sound and identified image that has been prerecorded on a magnetic memory disc within the hand held stethoscope housing containing amplifying circuitry, the prerecorded memory and a battery for supplying power. 
     The self-contained circuitry of the stethoscope is illustrated in FIG.  1  and comprises a microphone  10  located in the stethoscope chest piece, immediately followed by wide band low power amplifier  12  the output of which is applied to the switch  14 . Switch  14  preferably is comprised of four ganged, single-pole, single-throw switches which are connected into a spring loaded, momentary contact, single double-pole, double-throw configuration so that, in its normal state, one pole couples the amplifier  12  to a speaker for a sound output and the second pole couples the amplifier  12  to a monitor for a visual output of the waveform. When depressed, the first pole of switch  14  couples a prerecorded sound to the speaker and the second pole couples it to the monitor. 
     Thus, the output of amplifier  12  is coupled to terminal “a” of the switch  14  and normally passes to pole  16  of the switch. Pole  16  of switch  14  is connected to pole  20  of a double-pole double-throw switch  22  which, in a first position passes the signal from amplifier  12  to a second amplifier and a speaker and, in the second position, diverts the signal to the amplifier and speaker through a low pass filter  24  which may be switched on to eliminate all high frequency sounds above approximately 500 Hertz. 
     The output of the switch  22  is taken from the second pole  26  and after passing through a “privacy” phone jack  28 , is applied to the second or power amplifier  30 , the output of which is applied through a volume control  32 , having an “ON-OFF” power switch, to a speaker  34 . The output of amplifier  12  is also coupled to terminal “c” of the switch  14  and normally passes to pole  18  of the switch which is connected to the “X” or vertical deflection input on a small monitor  36  having, for example, a one or two inch oscilloscope tube. 
     Various heart and lung sounds are prerecorded along with a very short diagnosis of the defect causing the sound. All the heart and lung sounds and the associated suggested diagnoses are recorded on a miniature diskette which can be easily accommodated with the associated circuitry within the hand-held housing of the stethoscope. The approximate sector of the expected recorded sound on the diskette is selected by depressing a button on the housing and the recording may be “inched” forward and backward to find the desired location by an “up” or “down” sliding of the button of the spring biased switch  14  on the side of the housing. 
     The miniature memory diskette is contained in the memory and microprocessor, the output of which is converted into analog and applied to input terminals “b” and “d” of the switch  14  so that, when switch is momentarily depressed, the prerecorded signals are applied to the speaker  34  and to the monitor  36 . 
     FIG. 2 is a perspective view illustrating one end surface and the rear surface of the stethoscope that contains the selection controls and the audio and visual outputs and FIG. 3 is a top plan view illustrating the chestpiece on the stethoscope. 
     The stethoscope is contained in a hand-held size housing  40  approximately three inches square and one inch thick. Centered on one of the square surfaces is a funnel shaped chestpiece  42  about two inches long and containing a very thin diaphragm near its narrow end that is backed by the microphone  10  (not shown). A rubber ring  44  is stretched over the rim of the chestpiece to assure a tight seal to the skin of a patient. 
     On one side of the housing  40  are two controls: The volume control  32  which regulates the audio volume, and the switch  14  which is depressed to momentarily switch on the prerecorded sound from the memory  38  and which also may slide up and down for making forward and backward adjustments in the memory location. 
     The square surface opposite the chestpiece  42  contains the phone jack  28 , the small speaker  34 , and the monitor  36  which may have a two-inch or three-inch oscilloscope tube Also on this surface are seven buttons  46 , one of which is the low pass filter switch  22 , and the remaining six are for selecting the various pre-recorded subjects on the disk in the memory  38 . For example, the six buttons may be labeled Pulmonary Valve, Aortic Valve, Tricuspid Valve, Mitral Valve, Lungs, Blood Vessels. If Blood Vessels button has been depressed the switch button  14  may be moved so that Carotid Artery is displayed on the monitor. 
     In use, the stethoscope is turned ON with the power switch on the volume control  32  and the chestpiece is pressed at the appropriate body locations of a patient. The sounds picked up by the microphone  10  may be heard by earphones plugged into the phone jack  28  or they may be amplified by amplifier  30  and heard through speaker  34  while a visual representation of the sounds are seen by the monitor  36 . If the technician suspects any disorders, he may press the appropriate button  46  and adjust the sliding switch  14  to the location at which matching sounds are heard on the earphones or speaker and seen on the monitor from the prerecorded diskette. For each prerecorded sound visual, there is a brief message suggesting the problem; for example, the technician may have found coincidence between a patient&#39;s sound with a pre-recorded sound labeled “Mitral Regurgitation” indicating that the patient&#39;s examination showed a probability of a weak mitral valve and having a backward flow of blood through the valve into the left atrium.