Description

The object of the invention is an endovascular blood pressure sensor, which can be applied especially in cardiology, but also in angiology, neurology and invasive radiology.

Ischaemic heart disease is defined as a set of disease symptoms being the result of the chronic condition of insufficient provision of nutrients and oxygen to myocardial cells. As a consequence, this disease often leads to effort and rest pains, heart insufficiency, and in the case of atherosclerotic plaque rupture, also to myocardial infarction.

Ischaemic heart disease with all its subtypes is the most frequent cause of death in the majority of highly developed countries, and its most frequent cause is the atherosclerosis of coronary arteries.

Ischaemic heart disease has two forms: a chronic (stable) one and an acute (unstable) one, corresponding to the term of acute coronary syndrome. One form can change into another, since they differ only by their dynamics. In the chronic form, the lumen of the coronary vessel is narrowed, and in the unstable form the lumen of the vessel is abruptly closed as a result of a clot resulting from the rupture of the so-called unstable artherosclerotic plaque. Apart from pharmacological treatment of chronic ischaemic heart disease, there is also invasive treatment, called percutaneous transluminal coronary angioplasty (PTCA). It consists in the widening of the narrowed coronary artery using a balloon attached to the catheter introduced percutaneously into the coronary artery with the view to restoration of the adequate blood supply to the myocardium. The standard element of PTCA is the implantation of drugs-eluting stents into the lumen of the vessel with the view to diminishing the risk of restenosis and maintaining its patency.

A stent is a small spring, most frequently made from an alloy (e.g. of chromium and cobalt) or less frequently from a biodegradable polymer or bioresorbable material such as poly-L-lactide (PLLA), or another material with similar biophysical and biochemical properties, which is placed inside the blood vessel with the view to maintaining its patency. Stent flexibility is ensured by means of a special structure with ondulated connections of zigzag spans, which are the proper framework. An essential element of treating the ischaemic heart disease after the implantation of a stent is the monitoring of blood pressure through the blood vessel lumen. Currently the indirect monitoring through the evaluation of clinical symptoms is used most frequently. The intensification of chest pain prompts the decision to perform non-invasive or invasive diagnostics. No routine monitoring is performed using dedicated sensors and detectors.

The description of the patent no. US 7425200 B2 presents an implantable sensor with radio communication. It is an implantable sensor device, such as a pressure monitor, which is implanted into the left ventricle (LV), into other heart ventricles or into another location, out of which it transmits information on the pressure to a remote communication device using wireless connection. The sensor device can be implanted using a catheter, an endoscope or a laparoscope. The device can be fully mounted in the left heart ventricle or the heart wall using e.g. a corkscrew, a spiral anchor, a harpoon, a threaded element, a hook, a barb, a connecting element, a strap, a net or a shell absorbing the growth of the fibrous tissue. The implantable sensor device ensures less invasive long-term measurement of blood pressure or other physical parameters in the left ventricle. Wireless communication techniques cover radio telemetry, inductive connector, passive transporters or using the body as a conductor (hereinafter referred to as: "the interbody conductive communication" or "the personal area network"). The data from the receiver can be downloaded to the computer for analysis or display.

A stent antenna for the wireless, endovascular monitoring with the no. US 7452334 is also known. The description of this invention presents a stent device used for the maintenance of lumen patency with simultaneous endovascular monitoring. The device contains the structure with a set of tensile batons, which are capable of plastic deformation, thus forming a framework characterised by inductance, as well as electric capacity connected with a set of tensile batons and reacting to endovascular parameters. The capacity and inductance form a resonance circuit after the deformation of the set of tensile batons with the view to enabling wireless transmission indicating endovascular characteristics.

The description WO 2007081741 presents the implantable wireless fluid pressure monitoring system. The device for monitoring the fluid pressure is supported by this structure with the view to generating the signal related to fluid flow. A wireless transmitter based on this structure transmits the signal to the outside of the body. A reader on the outside of the body is also provided, for the wireless power supply of the monitoring device and the transmitter and for the reception of the transmitted signal. The internal reader also displays the speed of fluid pressure and/ or frequency.

Moreover, an American patent no. US6053873 is also known under the name of a pressure-reading stent. It consists of an implantable device for the measurement of blood pressure in the patient's body, including a stent with a cylindrical radial external wall and a central clearance. The pressure parameters sensor is attached to the stent and it measures the parameters related to the pressure speed of blood flowing through the stent. The transmitter transmits the signals reacting to the measured parameter to the receiver located inside the body.

The patent description EP 2055228 also presents a wireless pressure sensor, in which the sensor enclosure adapted to the fluid pressure received by it has been foreseen. A radio frequency tracer and a masking element can be located in the sensor enclosure. The masking element and the radio frequency tracer can be adapted to movement against one another. Relative location or movement can impact the response of the radio frequency tracer against the wireless signal (which can be for example broadcast from an external reading device), and thus indicate the speed of the fluid flowing through the enclosure.

Moreover, the stent pressure sensor is already known with the no. US 20110054333. ^This application describes the stent to be placed in the blood vessel of a patient, containing: the proximal end, the distal end, with principally circular cross section; an electromechanical micro system, an ultrasound sensor using the Doppler principle for the determination of patency and the pressure rate through the cross section, as well as the pressure drop between the proximal end and the distal end; the transmitter providing the signal to the external receiver outside the patient's body; as well as the coil receiving the energy from outside the patient's body together with the transducer for providing power supply to the transmitter. Moreover, a miniature wireless monitoring device in the form of a stent is also known (EP 2385859). ^The system provides for the arterial pressure transmission in vivo and it contains: a pressure sensor which collects the data on the arterial pressure in vivo; a radio transmitter which sends the data on arterial pressure in vivo to the receiver located outside the patient's body; a stent frame equipped with an integral antenna and the power supply source, supplying power to the system.

At present, there is no single manner of non-invasive evaluation of endovascular patency which enables to determine in an unequivocal manner the haemodynamic importance of possible stent narrowing.

The objective of the invention was the creation of an implanted endovascular device monitoring the occurrence of a haemodynamically important narrowing in the stent on the basis of pressure evaluation at the proximal and distal stent end, which shall enable non-invasive diagnostics and continuous monitoring of blood vessels patency, using wireless signal transmission and peripheral devices, including mobile devices (e.g. smartphones). The essence of the invention is the endovascular blood pressure sensor, mounted on the surface of an implantable stent from the side of its lumen and located in the blood vessel, characterised in that it has an elastic membrane transmitting external blood pressure, a blood pressure sensor, a wireless measurements transmission module and an enclosure, while the thickness of the endovascular blood pressure sensor does not exceed 50 μιη.

Preferably, the endovascular blood pressure sensor is made from aluminium nitride or an analogous material, ensuring adequate biophysical properties.

The invention has been presented in detail in the drawing, of which fig. 1 illustrates an endovascular blood pressure sensor 1 made from aluminium nitride, on which the elastic membrane 4 transmitting external pressure is shown, as well as the blood pressure sensor 5, the measurements wireless transmission module 6 and the enclosure 7.

Fig. 2 shows two endovascular blood pressure sensors 1 installed on the surface of the implantable stent 2 on the side of its lumen.

Fig. 3 presents the endovascular blood pressure sensor 1 connected to the implantable stent 2 using a soldering 8. The endovascular blood pressure sensor 1 is connected to the implantable stent 2 located in the blood vessel 3.

Endovascular blood sensors 1 presented in figures 1-3 are made from aluminium nitride, and their thickness is 50 μιη. Aluminium nitride is a biocompatible material with piezoelectric properties. Upon the conformation change, the endovascular blood pressure sensor 1 generates the low voltage electric current, read by the electromagnetic sensor attached to the skin above the examined vessel.

The thickness of the endovascular blood pressure sensor 1 ensures full resilience and flexibility, and the sensitivity of endovascular blood pressure sensor 1 ensures the detection of blood pressure variations with the sensitivity of up to 1-2 mm Hg. The change of pressure exerted on the endovascular blood pressure sensor 1 causes the change of electromagnetic field.

The wireless model of measurements transmission 6 presented in figure 1 serves as a receiver, a converter and a signal enhancer. The receptive function detects the changes in the electromagnetic field of the endovascular blood pressure sensor 1. The signal is enhanced and transmitted using a low-power transmitter to a peripheral device (e.g. an external electromagnetic loop) and from it to a mobile device (e.g. a smartphone) or directly to a mobile device. The analysis of signals provides information resources concerning pressure dynamics and their relations in the implantable stent 2.

The implantable stent together with the endovascular blood pressure sensor is introduced into the blood vessel using a balloon catheter, thus widening the vessel. Thanks to that, it is also possible to additionally restore the patency of the vessel, which has been diminished until that moment. The endovascular blood pressure sensor can also be an independent element attached to other endovascular stents used in clinical practice, including metal as well as bio absorbable stents.

The resilience of the stent with the endovascular blood pressure sensor is ensured by means of a special structure with ondulated connections of zigzag spans, which are the proper framework.

Stent implantation together with the endovascular blood pressure sensor is initiated through the introduction of a catheter terminated with a small balloon, onto which a stent is applied, for example into the coronary artery by means of a puncture of the femoral, brachial or radial artery. This balloon, apart from supporting the stent, also enables the restoration of artery patency by means of modelling the atherosclerotic plaque which narrows its lumen.

The endovascular blood pressure sensor serves for the wireless, non-invasive and continuous evaluation of pressure and pressures inside the vessel. The possibility of evaluation of pressure changes in the vessel and in the implanted stent in time enables the monitoring of patency and the verification of haemodynamic importance of narrowings in native vessels and also in implantable stents.

As a result, the endovascular blood pressure sensor enables quick recognition of acute ischaemia, the prediction of ischaemic threat, the determination of importance of stable ischaemia, the selection of an optimum moment for the performance of revascularisation treatment, and moreover the reduction of the exposure to complications related to the diagnostics (the administration of contract, ionising radiation), as well as advanced haemodynamic monitoring.

The solution according to the invention does not only allow for the evaluation of patency of the blood vessel, but also for the verification whether the gradually increasing narrowing in the vessel lumen is so advanced that it causes the ischaemia in the supplied tissues, and especially in the myocardium. Thus the application of the described invention enables the determination of the optimum moment, in which the patient can benefit the most from the renewed cardiac intervention and vessel revascularisation. The device can be used in the area of cardiology, angiology, neurology and invasive radiology. It can be used by the patients with cardiac and vascular diseases and it will significantly improve the safety and effectiveness of care in the case of patients after intervention treatments.