JPH089U - Device for assessing the mechanical status of the heart - Google Patents

Abstract

To evaluate the mechanical condition of his heart a patient inserts a finger into a cup containing a piezoelectric transducing film (31) for providing a pulse signal. An inflatable sleeve (13) puts the piezoelectric film in contact with the finger (11) of the patient. The inflatable cuff (13) is inflated to a pressure corresponding to a predetermined pressure within the range of substantially the diastolic pressure of the patient and half the diastolic pressure. The patient blows into a closed hose (24) having a small opening (23) and a pressure transducer (25) that provides a signal to a computer (15) representative of the pressure in the hose, and the comparator displays a cursor representative of the pressure in the hose on a display (16) along with limit lines representing 30 and 50 mm of mercury pressure. The pulse signal is also coupled to the computer. In use the patient blows into the hose while maintaining the cursor between the limit lines for about 20 seconds and then stops blowing. The computer (15) then displays or prints out signals representative of the pulse signal amplitude and rate, its derivative and integral, before, during and after the heart straining maneuver effected by blowing into the hose.

Description

[Detailed description of the device]

[0001]

[Technical field to which the device belongs]

 The present invention relates generally to assessing the mechanical performance of the heart, and more specifically, it can be performed with relatively inexpensive equipment, and requires relatively unskilled personnel to obtain reliable results. A heart pump that is relatively easy to operate and that can be performed with a system suitable for use in the private practitioner's office using non-invasive techniques, with little discomfort to the patient under evaluation. It concerns new devices and technologies that can provide a reliable indication of the mechanical performance of the operation.

[0002]

[Problems to be solved by the device]

 The present invention was granted to Dr. Kevin M. McIntyre on December 4, 1973, entitled "A Device for Detecting Mechanical Performance of Impaired Hearts and Its Equipment ( It corresponds to an improvement of the invention disclosed in US Pat. No. 3,776,221, entitled "DETECTING IMPAIRED HEART MECHANICAL PERFORMANCE AND APPARATUS THE REFORE". Disclosed in this patent is setting the time derivative of the global arterial pulsation pressure to some control level in the patient. The patient then undergoes a straining procedure, such as the Valsalva procedure, while recording the time derivative of the systemic arterial pulsation pressure signal. Desirably, the presence or absence of left ventricular dysfunction can also be detected by confirming and interpreting systemic arterial pulsation pressure, mean pressure, heart rate, and left ventricular ejection time.

An important objective of the present invention is to provide improved devices and techniques for assessing the mechanical performance of the heart.

[0004]

[Means for Solving the Problems]

 According to the present invention, a conversion means can be placed non-invasively near the patient's skin to provide an electrical pulse signal representative of whole-body arterial pulsation pressure, with pressure applied through the conversion means for conversion. There is a pressure-applying means, such as an inflatable cuff, for setting a pressure on the skin adjacent the means, preferably just above the diastolic pressure to half this pressure. The pressure adopted is substantially diastolic pressure, which appears to maximize sensitivity and reproducibility. It is desirable to connect a pressure source to the means for applying pressure so as to supply pressure thereto. There are means for displaying the pulsation signal characteristic of the electrical pulsation signal, preferably for displaying the peak pressure indication at each pulsation and the time between successive pulsations. An expiratory means for receiving exhaled air from the patient to be evaluated consisting of a confined volume with a small hole for releasing expiratory air and a confined volume coupled to the confined volume by the inspiring patient. It would be desirable to have a pressure sensing means capable of providing an electropneumatic signal representative of the pressure established therein. Desirably, there is a display means for providing an indication of the pneumatic signal as a function of time.

According to the invention, the conversion means are placed adjacent to the skin, preferably on the finger. Pressure is applied to the skin at least partially through the transducing means, preferably by an inflatable cuff that surrounds the finger and the transducing means. Desirably, when the desired pressure is reached, which is typically determined by observing a pressure indicator, in order to set the basal level of the pulsatile signal prior to subjecting the patient to tension treatment. ) A pressure source, such as a sphygmomanometer ball, which is connected through a hose with a valve that can be closed to), is connected to the cuff. In this procedure, the patient is allowed a certain time, typically the Valsalva maneuver, until the pressure indicating means indicates the pressure within a predetermined range, typically in a confined volume of 30 to 50 mm of mercury. Breathe expiratory means for 20 seconds during the duration of this straining procedure, as in stages I and II. The patient then breathes normally, during which time the converted pulsatile signals are recorded during Valsalva's stages I, III and IV. This signal may be processed to provide an indication of one or more of heart rate, time derivative of pressure signal, pressure signal integral, peak pressure, average pressure and diastolic pressure. One or more representations of these signals for those four stages of the Valsalva method can be observed to determine an assessment of the mechanical performance of the heart.

[0006]

DETAILED DESCRIPTION OF THE INVENTION Referring now to the drawings, and in particular to FIG. 1 thereof, there is shown a block diagram with a schematic diagram illustrating the logical arrangement of a system according to the present invention. When the patient 10 to be evaluated places his finger 11 between the piezo pulsating pickup 12 and the inflatable cuff 13, the analog-to-digital converter 14 gives a pulse signal converted to digital form, and The signal is processed by the microcomputer 15 to provide the display 16 with an indication of the pulsation detected by the pickup 12. A pressure source 17, typically a sphygmomanometer sphere, is connected to a cuff 13 via a hose 18 and comprises a valve 21, which comprises at least the inflatable cuff 13 at least. This is for closing the hose 18 when pressure is applied to the skin of the finger 11 which is partially surrounded by the pressure band 13 via the piezoelectric pulsation pickup 12. The pressure indicator 20 displays pressure, preferably substantially the diastolic pressure of the patient 10. If the cuff pressure is significantly higher than the diastolic pressure, the signal provided by the pickup 12 will be small, thus resulting in a less accurate diagnosis. The signal provided by the pickup can be maximized if the cuff pressure is near diastolic pressure. The diastolic pressure of the patient may be determined by measuring the patient's blood pressure in the usual manner.

A mouthpiece 22 (preferably replaceable) is provided with a hole 23 for connecting to a hose 24 which is closed at its distal end to define a containment volume and for releasing exhaled air. The pressure transducer 25 is coupled to the hose 24 and provides a pressure signal which is converted by an analog-to-digital converter 26 into a digital form representing the pressure within the confined volume. Microcomputer 15 processes this digital pressure signal and provides a display signal to computer display 16 which is representative of the pressure in hose 24.

Now that the system configuration has been described, its operation mode will now be described. The patient 10 inserts a finger 11 in the inflatable cuff 13 near the piezoelectric pulsating pickup 12. Next, the operator actuates the pressure source 17 to increase the pressure in the cuff 13 until the pressure indicator 20 indicates that a pressure of approximately diastolic pressure has been set. By opening the valve 21, the pressure of the inflatable cuff 13 can be reduced to the desired pressure immediately before and during the procedure. The patient 10 then blows into the mouth 22 to create a pressure within the hose 24 of the magnitude displayed on the computer display, which is preferably within the range of 30-50 mm of mercury and yet. Hold for 8-10 seconds. This tense breathing movement produces strain for Valsalva stages I and II. The patient then removes the mouth and relaxes, during which the recovery and steady-state phases of the procedure occur.

Turning to FIG. 2, there is shown a graphical representation of the pulse waveform just before and during the four steps of the Valsalva method for a normal response, which is indicated by the arrows labeled start and stop. It shows the change in arterial pressure with pressure during the control period immediately before the tension as a function of time during the period of tension between. There is an increase in pressure during tension (Stage I), a decrease in pressure (Stage II), a decrease below baseline (Stage III), and an increase after tension (Stage IV). The normal response characteristics of FIG. 2 are shown in Table 1 below for baseline conditions. 0, ↑, ↓ and ↓↓ indicate no change, increase, decrease and great decrease, respectively. An advantage of the present invention is that the measurements normalized to the duration of pretension in each patient during each examination characterize mechanical heart performance.

[0010]

[Table 1] Table 1 Stage I Stage II Stage III Stage IV (1) Ht. Rate 0 or ↓ ↑ ↑ ↓ ↓ (2) "dp / dt" 0 ↓ ↓ ↑ (3) ∫p dt 0 ↓ ↓ ↓ ↑ (4) Impulse amplitude 0 ↓ ↓ ↓ ↑ (5) Peak (systolic) pressure ↑ ↓ ↓ ↑ (6) Average pressure ↑ ↑ 0 or ↓ ↓ ↑ (7) Diastolic pressure or "low" pressure ↑ ↓ or 0 or ↑ ↓ ↑

Referring to FIG. 3, there is shown an intermediate abnormal response without overshoot defined by “systolic” pressure levels. The waveform of FIG. 3 for the baseline period has the characteristics shown in Table 2.

[0012]

[Table 2] Table 2 Stage I Stage II Stage III Stage IV (1) Ht. Rate 0 or ↑ 0 or ↑ 0 or ↓ (2) “dp / dt” 0 0 or ↓ 0 or ↓ 0 (3) ∫ p dt 0 0 or ↓ ↓ 0 (4) Impulse amplitude 0 ↓ ↓ ↓ 0 (5 ) Peak (systolic) pressure ↑ ↓ ↓ ↓ 0 (6) Average pressure ↑ 0 or ↓ ↓ 0 (7) Diastolic pressure or “low” pressure ↑ 0 or ↓ ↓ 0

Referring to FIG. 4, a graphical representation of arterial pressure as a function of time for an abnormal response to the Valsalva method is shown. The characteristics of this response relative to the baseline period response are shown in Table 3.

[0014]

[Table 3] Table 3 Stage I Stage II Stage III Stage IV (1) Ht. Rate 0 0 0 0 (2) "dp / dt" 0 0 0 0 (3) ∫p dt 0 0 0 0 (4) Impulse amplitude 0 0 0 0 (5) Peak (systolic) pressure 0 0 ↑ ↑ 0 ( 6) Average pressure 0 ↑ ↑ 0 (7) Diastolic pressure or "low" pressure 0 ↑ ↑ 0

Referring to FIG. 5, an exploded view of an exemplary pulsating pickup assembly 12 for use in accordance with the present invention is shown. The piezoelectric film 31 is stretched between the legs 32 of the support 33 and is in contact with a pair of leads 34 and 35 on both sides, which leads to the analog-digital converter 14 (FIG. 1). It is connected to a miniature hono plug 36 that can be plugged in. Ground shield 37 completes this assembly. Although FIG. 5 shows a generally rectangular shaped pick-up assembly, pick-ups of other shapes may also be used, for example pick-ups with a circular piezoelectric membrane surface exposed at the tip opening. Good. Membrane 31 is typically a commercially available polymer.

Referring to FIG. 6, there is shown a partial plan view of the end portion of the membrane 31 including the stem 31A for attaching the contact portion. Turning to FIG. 7, there is shown a partial side view illustrating details regarding connection to stem 31A. Leads 34 and 35 are soldered to metal buttons 34A and 35A, respectively, and these buttons are connected to corresponding sides on both sides of tab 31A by conductive epoxy coatings 34B and 35B, respectively.

Referring to FIG. 8, a diagram of a CRT (cathode ray tube) display is shown, which CRT display can be used to keep a patient within a selected pressure range during an examination. The upper, middle and lower horizontal traces 41, 42 and 43 show pressures of 70 mm, 50 mm and 30 mm respectively. The patient attempts to maintain the bright spot 44 between the traces 42 and 43 by insufflating the mouthpiece 22.

Blood pressure may be measured by standard cuff sphygmomanometry, or by an automated system such as the Doppler technique, or any other technique that provides an indication of blood pressure.

The particular components of the system of the present invention are known in the art. The technique of using a microcomputer to provide the peak pressure of each pulse and an indication of that pulse is well within the skill of one of ordinary skill in the computer arts. It is not explained in detail to avoid clarifying. In one particular embodiment of the invention, the microcomputer was an Apple 2e with an associated picture tube display.

The Valsalva procedure entails the sudden occurrence of an increase in intrathoracic pressure due to forced exhalation against the closed glottis. Such an increase in intrathoracic pressure will result in a reduction of venous return to the heart, and thus the filling of the heart's pump chamber will usually decrease. Impaired filling of the left ventricle (the main pump chamber of the heart) during this so-called “strain” phase results in an immediate drop in blood pressure in a normal person, followed by a rapid increase in pulse rate. become. In normal individuals, at the end of the “strain” phase, venous return to the heart increases to a point that generally exceeds the original baseline cardiac filling rate. The normal ventricle increases its activity above the “control” level to cope with increased filling (see Figure 2). As a result, "overshoot" occurs, causing pulse and blood pressure to exceed their levels during control or baseline levels. The human body senses this change and responds by slowing the heart reflexively with a detection mechanism in the carotid artery, the carotid baroreceptor. This normal response has several characteristics that distinguish it from the abnormal response in patients with ventricular dysfunction. That is, 1) There is usually a decrease in blood pressure during the “strain” phase. 2) There is an increase in heart rate towards the end of the “strain” phase. 3) Immediately after releasing the “distortion” stage, there is an “overshoot”. 4) During "overshoot", there is a deceleration of the heart rate. 5) Then there is a fairly rapid return of blood pressure, pulse pressure and heart rate to baseline levels.

In patients with heart failure, the physiologic response to the Valsalva procedure is quite different. One characteristic response, called the "square wave" response shown in Figure 4, is that blood pressure increases with the onset of the strain phase, and throughout the "strain" phase. , Pulse pressure and heart rate are maintained at the same level. The "recovery" phase following release of the Valsalva "strain" phase is characterized by a decrease in blood pressure to baseline levels, lack of "overshoot", and lack of cardiac slowdown during the recovery period.

According to the present invention, a sensitive analysis of the above differences is made by the use of the derivative of the pressure signal from the pickup, or by the analysis of changes in systolic pressure, pulse pressure and heart rate at various stages. The signal integration and heart rate measurements that can be made and which are small, relatively inexpensive, and relatively easy to operate and provide reliable results are known to this known device. Facilitates the use of physiological responses as a clinical indicator of cardiac status. The present invention provides for the presence of hidden dysfunction of the left ventricle (and / or right ventricle) in the clinic as well as significant abnormalities of the heart valve and the tightening sensation affecting the function of the heart's pumping action. , Provide a means by which it is possible to detect.

The present invention resembles a group of symptoms in which the syndrome of left ventricular dysfunction is associated with other very common types of heart disease states, some of which may be less threatening. Therefore, it is particularly advantageous. For example, the very common form of heart failure, shortness of breath, may be caused by other conditions. For example, shortness of breath is common among cigarette smokers. With increasing age and progression of diseases such as chronic lung disease, the ability to identify the presence of underlying heart failure as a contributor to limiting symptoms such as shortness of breath becomes increasingly difficult and important. The present invention helps to distinguish between heart failure and other effects that may cause physical symptoms similar or identical to those caused by it.

An important advantage of the present invention is that it can be used to evaluate the outcome of treatments for cardiac conditions. And ease of use, minimal discomfort to the patient, and availability to all practitioners can result in improved health care.

Above, a novel apparatus and technique for facilitating the assessment of the pumping status of the heart has been described. It will be apparent to those skilled in the art that many uses, modifications and new developments can be made in the particular apparatus and techniques described above without departing from the inventive concept.

[Brief description of drawings]

FIG. 1 is a schematic block diagram illustrating a logical configuration of a system according to the present invention.

FIG. 2 is a schematic representation of a representative pulsatile signal before, during, and after the Valsalva method for a normal or “sinusoidal” response.

3 is a representation similar to that of FIG. 2, except for an intermediate response without overshoot.

FIG. 4 except that it represents an anomalous or square wave response.
The display is similar to that of.

FIG. 5 is an exploded view of an exemplary embodiment of a conversion assembly for pulsation detection.

FIG. 6 is a plan view of a portion of a piezoelectric film having a metal backing.

FIG. 7 is a partial cross-sectional side view illustrating a connection portion to a piezoelectric film.

FIG. 8 is a diagram of a CRT display for assisting in adjusting patient exhalation pressure.

[Explanation of symbols]

 10: Patient 11: Finger 12: Piezoelectric pulsation pickup 13: Pressurization band 14: A / D converter 15: Microcomputer 16: Display device 17: Pressure source (sphere of blood pressure monitor) 18: Hose 20: Pressure display device 24 : Hose (confined volume) 25: Pressure converter 26: AD converter

Claims (2)

[Scope of utility model registration request] 1. A device for assessing the mechanical status of the heart of a patient with skin, wherein the pressure sensitive transducing means is responsive to arterial pulsations and is capable of producing pulsating signals representative of the arterial pulsations. Applying a controlled pressure to the patient's skin through means including the pressure sensitive transducing means and applying the controlled pressure to the pressure significantly above the diastolic pressure of the patient and the expansion. Pressure application means for maintaining within a pressure range of substantially half of the end-stage pressure, and changes in the pulsatile signal during and after the cardiac tonic procedure relative to the pulsatile signal immediately before the cardiac tonic procedure. An evaluation device comprising means for detecting. 2. A container means having said pressure sensitive transducing means and an inflatable means for exerting pressure on said patient's skin through means including said pressure sensitive transducing means, and said Claims for utility model further comprising means for selectively inflating inflatable means to said controlled pressure immediately before, during and at least immediately after said cardiac tensioning procedure. The evaluation device according to item 1.