U.S. patent number 3,674,018 [Application Number 05/077,662] was granted by the patent office on 1972-07-04 for assisted cardiovascular circulation.
This patent grant is currently assigned to American Optical Corporation. Invention is credited to Herbert E. Goldberg.
United States Patent |
3,674,018 |
Goldberg |
July 4, 1972 |
ASSISTED CARDIOVASCULAR CIRCULATION
Abstract
Apparatus arranged to aid a patient's cardiovascular circulation
by moving the patient synchronously and in proper phase with the
pumping action of his heart to reduce the pumping load on his
heart. An improved cardiovascular circulation aid is disclosed
utilizing apparatus for providing an accurate indication of the
occurrence of onset of systole and where body movement is precisely
synchronized thereto. Apparatus for phasing the onset of systole
with the beginning of movement of the patient includes ultrasonic
ranging and doppler devices, and/or an impedance
plethysmograph.
Inventors: |
Goldberg; Herbert E. (Concord,
MA) |
Assignee: |
American Optical Corporation
(Southbridge, MA)
|
Family
ID: |
22139354 |
Appl.
No.: |
05/077,662 |
Filed: |
October 2, 1970 |
Current U.S.
Class: |
601/2 |
Current CPC
Class: |
G09B
23/32 (20130101); A61B 8/00 (20130101) |
Current International
Class: |
A61B
8/00 (20060101); G09B 23/00 (20060101); G09B
23/32 (20060101); A61h 001/00 () |
Field of
Search: |
;128/24,24.2,33,50-52,2.5F,2.1Z |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Trapp; Lawrence W.
Claims
What is claimed is:
1. In apparatus arranged to aid cardiovascular circulation in a
patient by moving the body of said patient synchronously with
pumping action of the heart of said patient to reduce pumping load
on said heart, the improvement comprising:
ultrasonic transducer means operatively connected to external
surface areas of said body responsive to operation of said heart
for providing accurate timing for movement of said body.
2. Apparatus as recited in claim 1 wherein said ultrasonic means is
in ultrasonic communication with said heart and is responsive to
movement of said heart caused by said pumping action.
3. Apparatus as recited in claim 1 wherein said transducer means
includes ultrasonic doppler means responsive to blood flow in said
heart caused by said pumping action.
4. Apparatus as recited in claim 1 and wherein said transducer
means includes ultrasonic doppler means responsive to blood flow in
the ascending aorta of said patient caused by said pumping action,
for indicating successive occurrences of said pumping action and
monitoring means responsive to the operation of said doppler means
and to the movement of said patient for monitoring the operation of
said apparatus.
5. Apparatus as recited in claim 1 and wherein said transducer
means includes phase means for causing the beginning of movement of
said body to be related by a predetermined phase to the onset of
systole.
6. In apparatus arranged to aid cardiovascular circulation in a
patient by moving the body of said patient synchronously with
pumping action of the heart of said patient to reduce pumping load
on said heart, the improvement comprising:
impedance means adapted to be connected external the thorax of said
patient responsive to thoracic impedance changes caused by said
pumping action for providing accurate timing for movement of said
body.
7. Apparatus as recited in claim 6 and wherein said impedance means
includes an impedance plethysmograph.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to the varying of work-load on a human
heart, and more particularly relates to decreasing heart pumping
load of a patient with a weak heart. Apparatus is provided for
aiding a heart-patient's cardiovascular circulation by moving his
body in a certain direction and synchronously with beating action
of his heart, whereby the movement and the heartbeat have such a
precise phase relationship as to cause the work-load on his heart
to be substantially decreased.
2. Description of Prior Art
U.S. Pat. No 3,532,089 to Arntzenius, issued 6 Oct., 1970, entitled
"Method and Device for Assisting Cardiovascular Circulation" is the
most pertinent prior art. The substance thereof is included herein
by reference. This patent discloses an electro-mechanical system
for aiding cardiovascular circulation by moving the body
synchronously with pumping action of the heart. The system
discloses particular apparatus including a table for supporting the
human body in a supine position, a heartbeat sensing device such as
an ECG, and a power device (preferably hydraulic) for moving the
table synchronously with pumping action of the heart.
The heartbeat sensing device disclosed in the patent is selected
from a group of four devices. They are an ECG, a pressure
transducer of the implanted variety, an acceleration transducer,
and a ballisto-cardiogram. No other devices are disclosed.
All of these devices have certain disadvantages. For example, the
ECG represents an electrical wave-complex generated during beating
action of the heart and accurate repetitive detection of the
P-Q-R-S-T complex is sometimes difficult. In a given patient, the
R-wave (which is usually the largest wave of the complex), does not
always occur at a fixed time displacement from the onset of systole
and is thus not completely dependable as a timing signal. And, in
the case of aiding successive patients, because of differences from
patient to patient in their respective myocardium conduction and
contractility characteristics, the onset of systole is even less
precisely determined (with ECG apparatus) for each patient.
An implanted pressure transducer, although accurate in its
determination of systolic pressure, has the disadvantage that
implantation carries a risk of infection and is too delicate for
routine clinical use. It is desirable to use a non-invasive sensing
device. The acceleration transducer and ballisto-cardiogram,
although non-invasive, suffer from other disadvantages. The
indication of the occurrence of systolic pressure is not precise
enough.
The cardiovascular circulatory aid, as disclosed in the system of
the Arntzenius patent, is effective only if properly timed with the
pumping action of the heart. The patent does not disclose reliable,
non-invasive apparatus which has as much precision as desired. At
the onset of systole, when the ventricular pressure is at a peak,
blood in the ventricle is about to be forced into the aorta. If at
this point in time, a sudden movement is applied to the heart (the
body) in a direction that is generally axial with respect to that
portion of the aorta adjacent the aortic valve and is in a
direction towards the apex of the ventricle (away from the aortic
valve), the pumping load on the ventricle imposed by the aortic
valve and the aorta is substantially reduced.
The more accurate the timed relationship between the buildup of
ventricular pressure and the sudden movement, the more effective
the assistance to the heart. If, for example, the movement and the
onset of systole are substantially out of phase, an increase in the
pumping load occurs. This could be dangerous to heart-patient whose
heart is weak. He needs assistance and not an extra work-load.
(Extra load can be desirable, as for example in the case of healthy
people where load is purposely placed on the heart to strengthen
heart muscle.)
The present invention is non-invasive and provides more precise
indications of systolic pressure than previously available. The
heartbeat sensing device of the present invention is more precise
than any previously known external sensing devices and is as
precise as the implanted pressure transducer without its
disadvantages.
The present invention employs transducers external to the body.
They provide precise signals for timing movement of the patient and
either occurrence of peak pressure of the left ventricle, onrush of
blood flow in the aorta, or pulsation of blood flow through the
thoracic cavity. The occurrence of any one of these is an accurate
indication of the onset of systole and is an indication of when
movement should be applied to the heart.
SUMMARY OF THE INVENTION
The invention relates to a system for applying motion to the heart
of a patient in an accurate phase relationship to onset of systole.
The invention uses transducers that precisely determine onset of
systole. The present invention, in one embodiment, utilizes an
impedance plethysmograph to sense change in impedance of the
thoracic cavity due to blood flow. In another embodiment, the
present invention uses ultrasonic devices of the ranging and
doppler variety in ultrasonic communication with the heart and
aorta. These ultrasonic transducers precisely determine onset of
aortic bloodflow or movement of the myocardium, indicating onset of
systole.
An advantage of the present invention is that is provides a
reliable, easily useable, and accurate means of timing or
synchronizing the movement of a patient with his heartbeat to
assist cardiovascular circulation. Timing is based on actual left
ventricular pressure and not upon some representative phenomenon
such as an ECG. Also the present invention does not require
implantation.
It is an object of the present invention to provide an improved
cardiovascular circulation assist.
It is a further object of the present invention to provide a
reliable, and easily connectable device for obtaining precise
timing information for synchronization of ventricular pressure with
movement of the patient's heart.
Other objects and advantages of the present invention will become
apparent to one having reasonable skill in the art after referring
to the detailed description of the appended drawings wherein:
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagrammatic view of apparatus according to the present
invention;
FIG. 2 is a schematic diagram of the left ventricle and aorta of a
human heart, in ultrasonic communication with an illustrative
embodiment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In FIG. 1, patient 12 is supported on table 10 within body-outline
conforming material 13, and is held down by straps 16. The
patient's heart 14 is caused to reciprocate in directions L in
response to application of power to two stage electro-hydraulic
servo valve 32, which in turn controls the operation of a piston
cylinder hydraulic servo motor 34 which drives table 10. Hydraulic
power system 29 receives its input signal from hydraulic control
circuit 28 which in turn receives its input signals from feedback
potentiometer 33 and from electronic circuitry. The circuitry
comprises delay circuit 24, pulse forming circuit 26, trigger
circuit 20 and frequency detector 22. Heartbeat sensing device 18
provides an electrical input to this electronic circuitry. Device
18 is a transducer which receives its pressure input signal from
pumping action of the patient's heart. Detailed description of the
operation of this circuitry is found in the Arntzenius Patent
mentioned above and incorporated herein by reference.
FIG. 2 is a cross section of a human heart 114 showing the left
ventricle and the aorta and the aortic valve. Rapid movement and
slow return are in the directions depicted. The apparatus is shown
in ultrasonic communication with the aorta and with left ventricle
114. Transducer elements 128 and 122 in the preferred embodiment,
are equivalent to transducer elements 28 and 22 of U.S. Pat. No.
3,498,290 to Shaw et al., entitled "Pulsed Doppler Volumetric Blood
Flow Meter," the subject matter of which is included herein by
reference. Transducer element 122 locates and measures diameter of
the aorta and transducer element 128 determines velocity of blood
in the vessel by doppler frequency shift techniques. Aorta diameter
and velocity of blood therethrough are used to provide a precise
indication of blood flow at onset of systole. This determination is
accomplished by ultrasonic transducer excitation and return signal
processor 121 (a detailed description of a particular embodiment is
included in the Shaw et al. patent referred to above). The output
from transducer elements 128 and 122 are combined to provide
information to frequency detector 22, and trigger circuit 20 so
that they, in combination with pulse forming circuit 26 and delay
circuit 24, provide a signal to the power system to appropriately
move table 10 and the patient thereon at a precise time with
respect to the onrush of blood flow in the aorta.
Alternatively, or additionally, another transducer element can be
used. Transducer element 124 is in ultrasonic communication (as
shown by dashed lines 126) with heart 114. Reflected ultrasonic
energy 125 which is detected by transducer element 124 and
processed in processor 121, is an indication of movement of the
heart wall (or myocardium) in response to blood pressure therein.
This information can be used instead of, or in addition to, the
information obtained from the aorta, as another input to the
remaining electronic processing circuitry 121 to obtain a precise
timing signal. When element 124 is used to detect systole, elements
122 and 128 can be used to provide a signal to a monitoring device
used to monitor the overall operation of the system. Such a device
can be an oscilloscope.
Transducer elements 128 and 122 comprise an ultrasonic doppler type
flow measurement device, and transducer 124 comprises an ultrasonic
ranging device. When both types of devices are used simultaneously,
very accurate timing information is obtained, although as mentioned
either type may be used alone.
Other transducers may be employed to obtain a precise timing
signal. For example, an impedance plethysmograph, of the type
disclosed in U.S. Pat. No. 3,340,867, to Kubicek et al., entitled
"Impedance Plethysmorgraph," can be used to determine a precise
timing signal. The Kubicek et al. patent is incorporated herein by
reference. An impedance plethysmograph is a device adapted to be
positioned external the chest in the vicinity of the thorax and is
arranged to measure changes in the thoracic impedance due to
cardiac output, or blood flow in the thorax.
The impedance plethysmograph can be used to provide a signal to a
monitoring device used to monitor the overall operation of the
system. In this case, the timing of the system can be adjusted
manually until optimum operation is observed on the monitoring
device.
The invention may be embodied in other specific forms without
departing from the spirit or essential characteristics thereof. For
example, transducer elements 122 and 128 can be directed on heart
wall 114 rather than on the aorta. This would allow a volumetric
flow computation related to the heart and provide precise timing
information. The present embodiments are therefore to be considered
in all respects as illustrative and not restrictive, the scope of
the invention being indicated by the appended claims rather than by
the foregoing description, and all changes which come within the
meaning and range of equivalency of the claims are therefore
intended to be embraced therein.
* * * * *