ES2312256B1 - MAGNETIC SENSOR DETECTION OF THE DETERIORATION OF CARDIAC PROTESIS AND METHOD OF DETECTION. - Google Patents

Abstract

Magnetic sensor for deterioration detection of cardiac prostheses and detection method.

The present invention relates to a sensor Magnetic designed to perform, non-invasively, the early detection of cardiac bioprosthesis failure. Saying sensor is based on the absorption of electromagnetic energy by a magnetic material with the appropriate properties, incorporated into the valve veils, which moves with them during operation of the valve in its cyclic opening and closing process.

Description

Magnetic sensor for deterioration detection of cardiac prostheses and detection method.

State of the art

The present invention is framed within the sector of Magnetic Sensors and Magnetic Materials and their applications in the field of biomedicine. It is based on absorption of electromagnetic energy by a magnetic material with the suitable properties, incorporated into the valve veils, which moves with them during the operation of the valve in its opening and closing cyclic process.

This absorption of electromagnetic energy is performed from outside the patient's body, without implantation in said patient body of any electrical device or electronic.

State of the prior art. Background

There are two large groups of prostheses Cardiac: mechanical and biological.

Mechanical prostheses are guaranteed duration with proper maintenance, but required daily and lifelong anticoagulation treatment. The valves Biological have the advantage of not needing maintenance, but they have the disadvantage that their durability is relatively low, around 10 years, and with a wide range of uncertainty (± 2 years). On the other hand its failure is usually acute, which raises an undesirable incompetence between the risk excessive for the patient if the replacement is done too much late, and a high cost for Social Services if done unnecessarily soon.

These bioprostheses have various causes of failure, and there are many factors that can contribute to deterioration of said bioprostheses. The most important are the degradation Biochemistry and mechanical damage of connective tissue. Fatigue mechanical is produced by the large number of opening cycles and closure (approximately 30 million in one year) to which they are subjected the valves. Its effects are cumulative, and it manifests itself in linear breaks and / or perforations.

Other causes of failure are deposits of calcium, cholesterol and / or amyloid. Calcium deposits are the most important and develop especially quickly in Children and young adults. These deposits increase the stiffness of the veils coming in some cases to join their corners, restricting the opening and closing movement of the valve.

As far as our knowledge reaches not there is no sensor specifically designed to monitor the operation of the biological valves that, paradoxically, they are the ones that present the greatest degree of uncertainty regarding their operational life and whose quality control is extremely difficult for obvious reasons.

Regarding mechanical valves, there are some systems to detect possible dysfunction: electronic (patent number ES2100137 with the title "Heart valve prosthesis incorporating a pacemaker circuit and / or electronic supervisor"), electromagnetic (New electromagnetic methods for the evaluation of prosthetic heart valves, S. Udpa, J. Appl. Phys. Vol 91, No 10, (2002), 7769-7773) and image (Diagnosis and treatment of obstruction of a tricuspid Bjork-Shiley prosthesis, R. Beeuwsaert et al . Acta Cardiol 1983, 38 (1), 13-25).

The electronic and electromagnetic systems are based on the detection of the movement of the elements themselves metallic that integrate the valve. None of these systems are can apply to a biological valve, since in the latter case blood flow control is performed with valve veils of geometry similar to that of real valves and manufactured with animal pericardium (usually veal).

Imaging systems, also proposed for mechanical prostheses, are based on the use in construction of the valve of radiopaque materials that can be detected by radiodiagnostic techniques.

Explanation of the invention.

The present invention comprises a sensor magnetic to observe the operation and eventual dysfunctions of prosthetic biological heart valves (1) implanted in patients When we talk about "biological cardiac prostheses" we refer to those made with animal tissues; the "cardiac prostheses of the biological type developed with biocompatible materials "are those made with materials biocompatible artificial that maintain the shape of the prostheses Biological cardiac In the term "cardiac bioprosthesis" both types of cardiac prostheses are included

Said sensor is based on energy absorption electromagnetic (8) by a magnetic material (4) with the suitable properties (high magnetic permeability, high magnetostriction, high magnetoelastic coupling coefficient,  high coefficient of absorption of electromagnetic energy at frequency used), incorporated into the valve veils (2), which moves with them during the operation of said prosthesis of heart valve (1) in its cyclic opening process and closing.

The magnetic elements (4), in the form of thread, micro thread, nano thread, tape, or any other form that does not interfere with the normal functioning of the bioprosthesis, it placed on the veils (2) or on the structure (3) that supports these veils (2) so that they do not interfere with the natural movement of the same. Not to interfere with the natural functioning of the bioprosthesis, the magnetic elements (4) must have lower mass to 1 microgram and section of the order of 10 - 8 square meters or Minor. In addition, these elements must be biocompatible or be coated with a biocompatible material.

From outside the patient's body a wave affects the sensed bioprosthesis electromagnetic (8), of a frequency that can vary in a range from 10 Hz to 10 Ghz depending on the physical properties of the magnetic element (4) used, which includes both electromagnetic and mechanical properties of the material such as element morphology.

The movement of the veils (2) in the process of operation of said heart valve prosthesis (1) causes a cyclic change in the position of the magnetic elements (4) incorporated as well as in the tensions to which they are submitted.

Both phenomena produce a change in the intensity of the electromagnetic energy absorbed by said magnetic elements (4), resulting in a modulation of the intensity of the modulated transmitted wave (9), with a frequency equal to heart rate.

Said modulated transmitted wave (9) is detected also from outside the patient's body through a suitable receiver element (10) for the wave frequency of the electromagnetic signal (8) used.

A process of amplification (11) and demodulation (12) conventional allows recording or monitoring of the signal produced by the movement of the veils (2).

The dysfunctions produced in the movement of said veils (2) during the opening and closing of the valve, due to degradation, hardening, breakage processes, etc., cause a change in the modulated transmitted wave (9) monitored versus the signal obtained in optimal operating conditions. The comparison of both signals allows medical services accurately establish the moment at which the valve should be replaced. All without the need to implant in the patient no electrical or electronic detection device or transmission, nor to establish any type of material union to the valve or patient.

Embodiment of the invention

A specific embodiment of the invention as well as in vitro experimental testing of its operation is described below in an explanatory and non-limiting manner.

A commercial prosthesis model was used (1) mitral valve manufactured with veal pericardium as tissue biological. In each of the veils (2) of said prosthesis of valve (1) a magnetic micro thread (4) was inserted. Each thread magnetic (4) was inserted into the veil (2) parallel to its surface and in a position close to the flexural neutral fiber of said veil (2), so that the magnetic thread (4) remained completely embedded in the biological tissue, as it is represented in figure 1. This system eliminated the need for use fasteners, such as glue or sutures, that they intervene negatively in the movement of the veils. It was used an electromagnetic wave (8) of frequency 1 KHz generated in a way conventional by combining a wave generator (5), a power amplifier (6) and a transmitter coil (7). It has been made the detection of the modulated transmitted wave (9) using a receiver coil (10), an amplifier (11) and a demodulator synchronous (12) to extract the information. The scheme of operation is shown in figure 2.

In order to experimentally test in vitro the operation of the invention, a hydrodynamic installation capable of reproducing the flow rate, pressures and rhythm of a middle heart was designed and constructed (Figure 3).

In this specific case, for the incident wave (8) and for the modulated transmitted wave (9) a system was used of coils integrated in the installation (7 and 10). Installation It has a digital camera (16) that allows you to take pictures of the movement of the veils synchronized with the electromagnetic signal, thus allowing the amplitude and shape of the signal to be correlated with the movement of the veils.

Description of the drawings

To facilitate the understanding of characteristics of the invention and forming part of the memory descriptive, a series of drawings that explain the invention.

Figure 1 shows the scheme of a cardiac bioprosthesis with magnetic elements inserted in the veils:

one.

Cardiac bioprosthesis

2.

Veils

3.

Elastic structure that supports the veils

Four.

Magnetic elements inserted in the veils

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A general scheme is shown in figure 2 of sensor operation. Sensor scheme:

5.

Wave generator

6.

Power amplifier

7.

Antenna or transmitter coil

8.

Incident signal

9.

Signal modulated by the movement of the veils with inserted magnetic elements

10.

Antenna or receiver coil

eleven.

Signal amplifier

12.

Synchronous demodulator

13.

Microprocessor and memory of storage

14.

Synchronization generator-demodulator

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Figure 3 shows the scheme of the hydrodynamic installation for the in vitro tests of the sensors incorporated in the biological valves:

fifteen.

Valve seat

16.

Digital camera

17.

Regulation of systolic pressure

18.

Regulation of diastolic pressure

19.

Peristaltic pump

twenty.

Deposit of physiological serum

twenty-one.

Unidirectional Flow Valves

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Figure 4 shows the signal obtained with a sound valve in the in vitro tests of the sensor.

Figure 5 shows the signal obtained with an artificially damaged valve in the in vitro tests of the sensor.

Claims (4)

1. Magnetic sensor for detecting the deterioration of biological cardiac prostheses or of the type of biological prostheses
Rolled up with biocompatible materials (bioprosthesis) (1), by observing and / or monitoring, non-invasively, the dysfunctions produced in the movement of the valvular veils in their cyclic opening and closing process, which includes:

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to the minus one magnetic element (4) for each of the valve veils  (2), inserted in said valve veils (2) and / or in the structure that supports them (3), consisting of a biocompatible material or coated with a biocompatible material, with a mass of less than 1 microgram and section of the order of 10 - 8 square meters or Minor;

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a sender-receiver system (7, 10), which allows sending and receive a signal from outside the patient's body electromagnetic (8) of a frequency in a range of 10 Hz to 10 GHz;

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a electronic device consisting of a set synchronous amplifier-demodulator (11, 12), outside the patient's body, not materially attached to said body valve (1) or said patient, which allows to extract, analyze and record the modulation produced in said electromagnetic signal (9) by said magnetic elements (4), due to the movement of said valve veils (2).

2. Magnetic sensor for detecting deterioration of cardiac prostheses, according to claim 1, characterized in that the emitting and receiving system (7, 10) is formed by antennas and / or coils. 3. Magnetic sensor for detecting deterioration of cardiac prostheses, according to claim 1, characterized in that the magnetic elements (4) are in the form of a thread, micro thread, nano thread or thin tape. 4. Prosthetic deterioration detection method cardiac biologic or biologic type developed with biocompatible materials (bioprosthesis) (1) comprising:

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insert a bioprosthesis into the patient (1) sensed by including one or more elements magnetic (4) in each of the valve veils (2) and / or in the structure that supports them (3), being constituted said magnetic elements by a biocompatible material or coated with a biocompatible material, of mass less than 1 microgram and section of the order of 10 - 8 square meters or less,

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do influence an electromagnetic wave on the sensorized bioprosthesis of frequency between 10 Hz and 10 Ghz sent by an emitting element (7),

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detect, from the outside of the body of the patient, the modulation of the transmitted wave intensity by a receiving element (10),

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wear a record of the signal produced by the movement of the veils by an electronic device consisting of a set synchronous amplifier-demodulator (11, 12), outside to the patient's body and not materially attached to the valve (1) nor to the patient,

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compare the modulated transmitted signal (9) obtained at a certain time with the transmitted signal modulated (9) under optimal operating conditions to detect dysfunctions of the valvular veils (2).