US2680438A - Ballistic cardiograph - Google Patents

Description

June 8, 1954 M. L. EDWARDS BALLISTIC CARDIOGRAPH 4 Sheets-Sheet 2 Filed March 25, 1950 June 8, 1954 M EDWARDS v2,680,438

` v `BALLISTIC CARDIOGRAPH Filed March k25I 19570 y y y 4 Sheets-Sheet l June 8, l954 M. l.. EDWARDS* BALLIsTIc CARDIOGRAPH 4 Sheets-Sheet 3 Filed March 25, 1950 HMI] INVENToR.

Filed March 25, 1950 4 Sheets-Sheet 4 7 y, u m ma A lv\ m www w Q Ww w www /z 2 m m Patented June 8, 1954 UNITED STATES PATENT OFFICE This invention relatesto improvements inapparatus` for recording theballistic eects .produced by pulsations. of the heart and. the rhythmic movements. of the blood in thehuman body.

The most common and. elementary clinical tests employed for investigating a. pa'tients heart the electrocardiograph has been devised to record. graphically the nature of certain electrical AWell recognized.

just andi use, andi the results generally included considerable error and distortion'. from'. various.

disturbances which` could not be'. eliminated..

General objects of the present ballistic cardipable of greater existing apparatus.

Particular objects. areV to provide improved apparatus which is sensitive to any vibratory sounds may be heard in the stethoscoperbut the. limitations. .of

invention.. are,v

ter of gravity of a patient. produced by thev re'- sultant ballistic effects of such pulsations and blood stream movements..

Other objects are to provide novel and improved supporting responsive mech anism during periods of. patient unrest.

Certain features4 of the' present apparatusmay be used without 'other features; but it" ispre furnish a nominalV dampenin'g effect.

' is4 connected' ToY avoidV relative movement patient and theF iioatm'g support, th'esupport the centerof gravity of the straint without critically impairing the desired ballistic response. To effect the return movement toward a centered position the frictional dampening force is insufficient; the restraining and restoring force must be elastic or the equivalent. It is recognized that any elastic or other restoring force for this purpose will establish a natural vibrating frequency of the oscillating mass comprising the patient and support. Such restoring force must, therefore, be adjusted to keep this natural frequency lower than the range of heartbeat frequencies in order to avoid resonance at the fundamental natural frequency, or any harmonic, of the potential oscillating mass.

It is found that the slight ballistic effects of the relatively slow shifting of the center of gravity of the body from respiration can effectively be eliminated by suitable centering springs without appreciably affecting the response to the ballastic effects of the heart action and blood stream. lt is also recognized that such systolic and diastolic action of the heart does not produce a simple ballistic effect in any particular direction relative to the orientation of the body, but it is found that there is a measurable resultant movement of the center of gravity of the body in a longitudinal direction which is useful for the present purpose. The present apparatus is designed to provide freedom for this movement, and to provide a sensitive, convenient, responsive mechanism for recording the movements over a period of time, for clinical use.

When the human body is subjected to any sudden force, or impact, it behaves as an elastic medium, and a train of vibrations is initiated at the natural frequency of the body, as when a tuning fork is struck. Such vibrations have been observed by disposing a fresh cadaver on a rigid stationary support and holding a sensitive vibration pick-up against the bottoms of its feet. 1f the body is tapped on the head with a single stroke, a train of vibrations will appear clearly on a graphic record produced from the vibration pick-up device. Vibrations of vthis nature are produced in a living body by heart action. The graphic records made by previous known ballistic methods have recorded these trains of damped vibrations to such an extent following each impulse from the heart that the heart action itself was obscured and could not be analyzed satisfactorily. In the present apparatus, such vibrations of dii-ferent parts of the body relative to its center of gravity are eectively isolated from the recording mechanism, and the only movement fed into the amplifying system is the longitudinal movement of the center of gravity of the body resulting from the vector sum of the ballistic effects of the heart and the pulsating blood streams throughout the body.

For a theoretical analysis of the ballistic mechanics involved, let it be assumed that a living body is disposed at rest, horizontall on a fricticnless horizontal surface, free of all other external contact. Such a body forms a closed system having a center of gravity which remains stationary and cannot be moved horizontally by any muscular effort of the body itself, though parts of the body can move relative to other parts. When the heart contracts, quantities of blood are different directions away from the heart and, since the heart is not at the center of gravity of the system, the center of gravity of the system is thereby shifted relative to the body, considering tne body as a frame carrying a network of pipe lines. However, with a fricticnless support the actual movement in space is that of the body frame and its center of gravity because, as stated, the center of gravity of the whole system, including the blood, cannot move. This is the movement to which the present apparatus is intended to respond, and all mention of the center of gravity of the body in the specification and claims refers to the body frame and pipe line network as distinguished from the stationary center of gravity of the whole body system. Energy losses from friction tend to reduce the amount of movement in a mechanical apparatus but do not alter the principle of operation.

The term ballistic is thus employed to describe the response of the present cardiograph to the movement, or recoil, of the center of gravity of the patients body frame, tissue, and pipe line network when a quantity of blood is propelled or moved suddenly within the body by heart action. The term ballistic distinguishes the response to such ballistic movement from 'Y response to electrical manifestations of heart stimuli, response to variations in the blood pressure, and response to vibratory movements of some part of the body relative to its center of gravity.

Other objects and advantages will become apparent, and the invention will be better understood with reference to the embodiments illustrated on the accompanying drawings and described in the following specification. It is to be understood, however, that the drawings are not intended to limit the invention, as various changes may be made in the construction and arrangement of parts without departing from the spirit of the invention. Also, as hereinabove pointed out, advantages may be obtained for certain purposes by using some features of the invention without others.

In the drawings:

Figure l is a side elevation view of a preferred embodiment of the complete apparatus of the ballistic cardiograph wherein the patient is supported on metal rollers;

Figure 2 is a bottom plan view, on a reduced scale, of the noating panel under the patient in Figure l;

Figure 3 is an enlarged detail View in side elevation view of one of the rollers shown in Figure l;

Figure 4 is an end elevation view of the roller shown in Figure 3;

Figure 5 is an enlarged sectional view showing the construction of the connecting link between the oating panel under the patient and the translating device;

Figure 6 is a side elevation view of a diierent form of support employing inflated rubber rollers;

Figure 7 is a side elevation view of a modified form of floating support to be used on a bed or other conventional structure;

Figure 8 is a cross sectional view taken on the line 8-3 of Figure r1;

Figure 9 is a longitudinal sectional view of the translating device shown in Figures l, 6 and '7;

Figure 10 is an enlarged detail view showing the connection between one end of the link in Figure 5 and the translating device shown in Figure 9;

Figure 1l is a fragmentary elevation view of the light shutter shown in Figure 9;

c. t f -Figure '12 iis afsectional r-vievv taken onf-the line l2--|2 of Figure lfl;

Figure V13 is -a 'top -plan rv-ieW'of the translating device with parts of the cabinet broken away;

' -isanenlargedperspective:Viewof-the lIn Figure A1, thepatientsbody I0 rests `upona lightweight but rigid .panel 'H of plywood "or *the like, having freedom of movement infa longitudi- 2, with a plurality of short-metalrails "t2 fto'support the panel on grooved rollers I3. Rollers I3 are mounted on anti-friction bail bearings (not shown) on short shafts -I4 which are supported on a base board 'l5 for use on a rigid level table I9. The vmoving parts of this support, comprising panel Il, rails l2, and rollers i3, have relaoperative embodiment the Apanel H Aand Arails At2 weigh `fifteen pounds. A lessweight in these parts would be 'desirable if it could kbe obtained without -loss of rigidity, but to 20 pounds vis .f

considered satisfactory. A

The under side of panel fi l -is further-equipped Witha depending lug i6 positioned between agpair or" spaced abutments il onthe rbase :15. of light coil springs I8 are seated betweenY .the abutments I? fand opposite sides of the'lug I6 movement. Y

The spring force exerted by the springs t8 upon the panel i l is an important consideration to the proper of th quency for the 'spring and `L`mass combination shown Figure 1 --varies from 45 cycles uper c1utch-and1centering mechanism shown 2kin lFigcircuits. byfmeans any other purpose- The construction land `mrangernent' of the link Dis` shown in Figuref. Oneend of 4the panelli he translating Vdevice l 'has a movable/vele# ment with asimilar plate 13d-'projectingtherefrcm.

members 'is 'equipped VWith a conical socket 35, andthe device?! is preferably supported `upona ytable r36 may -bedisposed adjacent the plate IvStand 'at approximately the same Vlevel for so thatthe plate 3313/ plates 33 and 34, even though these plates may be somewhat out of alignment and on slightly different levels.

In Figure 6, the patient 45 is supported on a rigid panel 46 which is similar to the panel il in Figure i, except that it is not equipped with the rails l2. The under surface of the panel 45 is made smooth and fiat, and rests upon a plurality of inflated rubber rollers 41. These rollers rest upon the smooth and flat top surface of a second panel 48 on the table I8. Springs i8 center the panel 46 as in Figure 1, and are stii enough, acting in conjunction with the elasticity of rollers 41, to prevent response to respiration.

Figure 1 shows a modified form of supporting means for a patient 50 who cannot be removed from the bed 5 I. Infiated cylindrical rubber tubes 52 are placed transversely across the mattress to support the rigid lightweight panel 55. The tubes 52 and panel 55 can be placed on the mattress and the patient 55 transferred thereto with a minimum of disturbance. The tubes 52 are preferably larger than the tubes 41 in order to hold the panel 55 above the mattress when the mattress is depressed under the tubes. Both types of tubes constitute elastic and pneumatic cushion means to support the rigid members 4t and 5,5 for horizontal movement in a longitudinal direction. The tubes 52 are only partially inflated, so that they will be considerably flattened under the weight of the patient, as shown. With this shape of cross section, and with the proper wall thickness in the tubes, the tubes themselves will have the desired centering effect and will prevent response to respiration, making the springs i8 unnecessary. Centering springs may be added, however, if necessary.

The tubes 52 preferably extend beyond the side edges of the panel 55, so that the ends of the tubes will bulge up as shown in Figure 8. When the tubes are deformed to this shape, they oier more resistance to rolling, particularly under the very minute movements imparted to the panel 55 by the ballistic effects of the pulse action. Longitudinal movement of the panel tends to compress the tube wall on one side of the tube and slightly stretch it on the other side beneath the panel. Shear stresses are produced in the rubber tube in the projecting end portions. For very minute movements, the combination of compression, tension and shear forces in the rubber produce the necessary amount of restraint and have the desired centering effect, by virtue of the elasticity of the rubber itself, without impairing the freedom of movement of the panel to respond faithfully to longitudinal movements of the center of gravity of the patient.

With the arrangement shown in Figure '1, the table 3B with the electrical equipment may be brought directly to the patient in a conventional bed, in cases where the patient cannot be moved to the equipment. The ballistic cardiogram may be obtained easily and quickly without any sacrice of sensitivity and without endangering a very weak patient.

The rolling friction which occurs in the metallic or pneumatic roller supporting system provides sufficient dampening of the system to prevent unwanted movements. These movements may be caused by respiration of the patient, or by overshooting of the elastic centering force from inertia. It is found that the rolling friction has the desired dampening effect with minimum interference to the free movement of the body and supporting panel under the cardoballistic effects produced in the patients body, which effects it is desired to utilize as the source of the input signal for the oscillograph recording mechanism.

The characteristics of the present type of support shown in Figures l, 6 and 'I are to be distinguished from the characteristics of direct support of the body on a stationary table top. In the latter case the body tissue bearing on the table top establishes a resilient connection between the main mass of the body and the table in which neither the spring rate nor the dampening can be controlled. Any ballistic impulse in such body excites two different types of vibration in the body. There is a movement of the center of gravity of the body relative to the support and also a movement of different parts of the body relative to each other, both movements tending to start trains of vibrations. With such support, a vibration pick-up cannot be applied to the body to respond solely to the original ballistic impulse and reaction.

With the present support, relative movements of parts of the body are not transmitted to the floating support. The support can respond only to movements of the center of gravity of the body, and the dampening effect and elastic centering force acting on these movements can be controlled to eliminate resonance conditions and to eliminatel body disturbances from other than cardio-ballistic causes.

Translating device Figure 9 is a sectional view illustrating the construction of the translating device 2l. This device contains a special clutch mechanism 55 for transmitting the longitudinal movements of link 2G to a shutter or occluding device 56 which controls the amount of light from electric bulb 51 which may fall cn the light sensitive cell 10. In the illustrated embodiment, the cell 10 is of the self-generating type, and the'output circuit 22 shown in Figure l merely connects the voltage generated by the cell to the input circuit of the electrocardiograph 25. Other known types of circuits may be adapted to the purpose of varying the signal in the output circuit 22 in accordance with the movements of the link 25 without imposing any restraint upon such movements.

The light bulb S1 is mounted in a socket 1| which is energized from the supply source 28 through a switch 12 and rheostat 13. The signal intensity in the output circuit 22 may be adjusted at its source by varying the temperature of the filament in bulb 51 by the rheostat 13, in addition to the conventional controls provided in the usual cardiograph apparatus 25. A pilot light 14 is connected with the light 'circuit t0 provide a visual indication when the light is turned on. y

Figures ll, l2 and 13 illustrate details of construction of the occluding shutter 55. The shutter is pivotally mounted on pin 19 to swing in a vertical plane when it is moved by a rod 8i] having one end pivotally connected with the shutter by means of the pin Bi. When the apparatus is in operation, the clutch mechanism S5 effects a direct mechanical connection between the rod 8i) and a rod 82 shown in Figure 10 which carries the plate 34 to support one end of the link 20.

The pin 8l is quite close to the pin 19 in order to magnify the movement of the upper end of shutter blade 65 which is disposed between the light 61 and light sensitive cell 10. The upper end on the base |08. A spring |06 on thezirame .H32

tube..

The rearward end of sliding frame |62, comprisesa bridge |5..upon|which is secured a for- Plate |22 carriesastirrup |29having arpad of material' lf form-ing a clutch element seats against an adjustable the lower end extends throughv an opening |35:` -in thefplate 22? tobearagainst the tube Iii-.order to maintain the parts normally in their restf orcentered` positionas shown in Figure l' mately half the sensitive surface of the cell' lil'is shaded from the rays ci the light source 6l. Once made, this adjustment does not have to be changed. Movement of the shutter 55 in one dioftheroda.

In Figure 9 there is also disclosed a convenient deviceiory actuatingl the; lever |25 to-operate the the device 2|. plunger Milout lever |25'.

Spring of Contact Witn the upper endof having a pneumatic bulb |46 shownin Figure 1. Whentht bulbissqueezedair is forced into cylinder |425 to driveplunger i 40.1 against lever |25, rotating it ina clockwisey direction abouti its pivot |26.,

Figure 9 further showsla lever 5U mounted on a xedfpivot lili; The lowerend of this lever is positioned to engage a: pin |52 on the sliding frame it". as shownfalso invFigures .141 and 15. By means off this lever', thenormally stationary frame |02 may be shifted'ioiward until stop pin |03 engages the forward stop screw flte. The amount ofthis movement. is equal to the space', or gap, |08; between the end ofstop screw |918 and the adjacent surface of pin 13' when the partsare in the normal' position shownl in Figure 15, and this gap may be accurately: measured and. adjust-ed by a suitable gauge. When the clutch |30 is. disengaged, ,as shown in Figure 17, and: they sliding frame |92 moved'v forward by meansof the lever 55e, the motion is transmitted through rod fto is tracedwhen stop pin: screw |05'. This provides-aA convenient and accurate calibrationY directly on the curve of the cardiograrn.

Operation rThe patient is placed on one of the supports shown in Figures 1,6,.01` '7. After allowing some be desired toy exercise? the patient and` thenmake therrecord immediately after. the exercise.

The-parts in thetranslatingdevice 2| are illusl trated. inI disengaged andf centered positions in Figure 17 'which ,is their normal restposition when ai record. is not inv Tube il is heldfina predetermined or centered position-bythe engagement of-centering block liwith thelug- IZ-l.

When it: is desired totracefa ballisto-cardiogramfcurve, the upper/endoflever |25 is pressed Si@ with a force determined by the adjustment raf-spring it. Further upward movement ofthe centering block |2 frees the lug |2|, and the rod el? is then clamped` in tube to transmit movementsfrom the link 20. di-

and rod to actuate the shutter t5. When.` the bulb Meis squeezed, the electrocardiograph machine. 25, is operated to make the graphic recoroh The shutter will be actuated in response to. movementsY ofv the link 25 only while-theupper endof lever 251s depressed rearwardlyr by theaction of rodi 82 from. tube HJ and' recenter the latter in H13? engagesthe rear stop vure l. The top curve -curve is obtained by vstraight base line to be drawn in the center of the curve area until the electrocardiograph 1s turned ofi.

Figure 19 illustrates the type of cardiogram curve obtained with the apparatus shown in Fg- I'H is traced by conventional electrocardiograph equipment, and represents a typical eleotrocardiogram curve, This placing electrodes connected with one of the input circuits-2l' in contact with spaced points on the body of the patient. This conventional apparatus is not necessary to the invention and is not shown in Figure l, but it may be used in conjunction with the novel apparatus illustrated in order to trace the two curves simultaneously for comparison. The several input circuits 2l of a conventional electrocardiograph are independent of each other, and present electrocardiograph equipment may include as many as six input circuits for tracing six different curves simultaneously on the record 30. The translating device 2| utilizes only one of these input circuits, thereby leaving the other fixe circuits available for any other type of simultaneous analysis which may be desired, such as the curve |10.

In the record shown in Fig. 19, the vertical lines are printed on the paper to indicate fifths of a second in time, and the upper and lower peaks and |12, spaced at approximately one second intervals, form a typical electrocardiogram curve. These peaks indicate slight variations in the electrical potential measured between diiferent points on the surface of the body which occur in rhythm with the heartbeat.

The curve |75 resulted from the signal from output circuit 22 in Figure l and was traced simultaneously with the curve |153. On the curve |15, the straight horizontal line it forms a reference or base line which was traced in the center of the curve was centered by block 12S with the clutch |39 disengaged as shown in Figure 17. Offset portions |8| were traced while lever |50 was shifted to hold stop pin |63 momentarily against the forward stop IDA. Hence, the vertical distance on the chart between the parallel lines |89 and |81 is a measure of the known distance |08 between the end of stop screw me and stop pin |63 shown in Figure 15.

When the bulb le@ is squeezed, clutch |39 is engaged' to produce the graphic record at |15 Lof thc longitudinal movements of the center of gravity of the patient with respect to the time axis. Portions of the curve |15 above line |88 indicate movements in one direction from the centered position and portions below line |80 indicate movements in the opposite direction from the centered position. The ordinate distances of points on the curve from line |80 bear a linear relation to the amplitudes of said movements at the instants considered, whereby the extent, duration and velocity of any movement of the center of gravity of the patient may be determined from measurements on the chart.

Having now described my invention and in what manner the same may be used, what I claim as new and desire to protect by Letters Patent is: l. In a ballistic cardiograph, a rigid member for supporting a patient, said member having a small mass relative to the mass of the patient, rollers supporting said member for movement in one direction, a' mechanism for indicating a characteristic of said movement, and a link interconnecting said rigid member and said mechaarea when the tubular sleeve nism for direct response of said mechanism'to said member.

2. In a ballistic cardiograph, a rigid member for supporting a patient, said member having a small mass relative to the mass of the patient, elastic rollers deformable under the weight of a patient supporting said member for movement in one direction, a mechanism for indicating a characteristic of said movement, and a link interconnecting said rigid member` and said mechanism for direct response of said mechanism to said member.

3. In a ballistic cardiograph, a rigid member for vsupporting a patient, said member having a small mass relative to the mass of the patient, elastic cushionA means supporting said member for relativelyr free horizontal movement in one direction, a mechanism for indicating a characteristic of said movement, and a link interconnecting said rigid member and said mechanism for direct response of said mechanism to said rigid member.

4. In a ballistic cardicgraph, a rigid member for supporting a patient, Said member having a small mass relative to the mass of the patient, pneumatic cushion means supporting said member for horizontal movement in one direction, and a mechanism for indicating a characteristic of said movement, such as amplitude, operably connected directly to said member for response to said movement.

5. In a ballistic cardiograph, a rigid member for supporting a patient, said member having a small mass relative to the mass of the patient, rolling friction means supporting said rigid member for movement in one direction, elastic centering means connected with said rigid member to urge said member toward a predetermined position with sufficient force substantially to eliminate response to respiration of the patient, and a mechanism for indicating a characteristic of said movement connected with said rigid member.

6. In a ballistic cardiograph, a rigid member for supporting a patient, said member having a small mass relative to the mass of the patient, pneumatic cushion means supporting said rigid member for horizontal movement in one direction and tending to center said member in a predetermined position with sufficient force substantially to eliminate response to respiration of the patient, and a mechanism for indicating a characteristic of said movement connected with said rigid member.

'7. In a ballistic cardiograph, a rigid table, a rigid member for supporting a patient, said member having a small mass relative to the mass of the patient, rolling friction means supporting said rigid member on said table for movement in one direction, elastic centering means connected with said rigid member to urge said member toward a predetermined position, and a mechanism for indicating a characteristic or said movement connected with said rigid member.

`8. In a ballistic cardiograph, a member for engaging a patient to be tested, a translating device for converting minute mechanical movements into current variations in an electrical circuit, a socket in said member, a socket in said translating device, and a connecting link having opposite ends resting in said sockets for universal angular adjustment to transmit movements of the patient to said translating device.

9. In a ballistic cardiograph, a member engaging the patient to be tested, a translating device Weight ofsaid link to ehmmate lost motion in the connections.

10. In a ballistic cardiograph, a member for engaging a patients body to respond to minute movements of the body, means for varying an electric signal in response termined position.

11. In a ballistic cardiograph, a rigid member for supporting a patient, means supporting said member for free longitudinal movement, elastic means for centering said member in a predeter- 14. In a ballistic gage the body of signal varying member in a predetermined positi n w graphic indication, engage said clutch means.

in the opposite direction to engage said clutch and disengage said centering means.

16. In a translating device for a ballistic cardiograph and the like, means for varying an electance from centered said clutch is disengaged, for Calibrating the device.

17. In a translating device for a ballistic cardiograph and the like,

References Cited in the le of this patent UNITED STATES PATENTS OTHER REFERENCES American Journal of Physiology, volume 142, August 1, 1944, pages 1-11, by Nickerson et al. (Copy in Scientific Library.)

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