Translation (Rule 12.3)

Implantable RF defibrillator

Field of the invention

The present invention relates to a defibrillator having an internal implantable component and an external coupled component equipped with output radio-frequency (RF) antenna.

State of the art

Defibrillator technology is based on that of the pacemaker, which was invented some twenty years before. Precisely on account of the advantages obtained in the field of pacemakers, the defibrillator has been able to evolve with a surprising rapidity from 1980 to the present day. The first implantation of a defibrillator in a human being was performed in 1980. Before then patients affected by arrhythmias were treated with pharmacological therapy, which is able to reduce the incidence of arrhythmic phenomena, but not to interrupt them in the case where they arise.

The introduction of the implantable defibrillator in clinical practice has represented a fundamental passage in modem cardiosurgery. The technological evolution in this case has rendered possible an increase in the effectiveness of the instrument and the reduction of the invasiveness of the surgical intervention of implantation, which initially was very debilitating.

As compared to pharmacological therapy, the aspects to be considered are, on the one hand, the possibility of reducing the effects deriving from the toxicity of the drugs, and on the other, the period of post-operative convalescence.

In the first implantations, proceeding to an operation as that of opening of the thorax, effected in total anaesthesia, with the need for intensive therapy subsequent to the operation, had of course a considerable impact on the times of recovery of the patient.

With the introduction of transvenous catheters and subsequently of endocardial implantation, the invasiveness of the intervention has obviously undergone a decrease: the times of recovery for the patient have shortened sensibly, thanks also to the lower incidence of complications.

Also the introduction of pectoral implantation has had a considerable impact on the organizational aspects of hospitals, which have adopted new-generation apparatuses. The post-operative stay in hospital is on average just two days. Consequently, as compared to the past, resources such as personnel, equipment, and number of beds are more freely available.

There are moreover various aspects to be considered as regards costs: in fact, even though the initial cost of the device may seem high, therapy with implantable defibrillator has

presented immediately a better cost/effectiveness ratio as compared to pharmacological therapy. This because different studies highlight that the rate of mortality in the latter case is higher than in the former.

The internal cardiac defibrillator (ICD) is usually constituted by a generator implanted subcutaneously and by one or more electro-catheters positioned in the cardiac chambers, capable of detecting, interpreting and storing the intrinsic electrical activity of the heart and, if need be, of supplying stimulations (antibradycardial therapy) or electric shocks (antitachycardial therapy).

The implantable cardiac defibrillator is the only device capable of recognizing a malignant ventricular tachyarrhythmia and of providing automatically an immediate electrical therapy in patients running the risk of sudden cardiac death. On the basis of the stimulation modalities, there may be distinguished single-chamber, dual-chamber, and biventricular (three-chamber) ICDs. Single-chamber devices, which were the first to be launched on the market and are still in use, have a single electrode implanted in the right ventricle with functions of stimulation and registration (pacing/sensing) of the activity of a cardiac chamber.

Dual-chamber ICDs require the implantation of two electrodes, one in the atrium and one in the ventricle, and enable stimulation, analysis, and classification of both the ventricular

rhythm and the atrial rhythm. The presence of an electrocatheter in the right atrium enables more precise classification of the cardiac rhythms and, in some models, also interruption of some forms of supraventricular tachycardia, such as for example atrial flutter.

The various models produced by the various manufacturers differ from one another substantially on the basis of programmability, algorithms and parameters of stimulation and of storage of data.

Biventricular ICDs unite in a single device a biventricular pacemaker and a defibrillator. The function of biventricular pacemaker is obtained through the insertion of an electrode in the coronary sinus capable of stimulating the left ventricle. In addition to the two standard electrodes present in the right atrium and ventricle, it enables atrial-ventricular re- synchronization and re-synchronization between the right ventricle and the left ventricle, with an improvement in the contractile function of the heart. These ICDs are indicated in the therapy of congestional cardiac decompensation.

In all the cases of internal cardiac defibrillators, the problems that are encountered are due above all to the dimensions and weight of these devices that are greater than those of a normal pacemaker. In addition, they are particularly complex instruments, capable of performing numerous control functions, which are automatic, are linked to internal management software, of extremely delicate application, and frequently take away from the

doctor the possibility of intervention. Both of the factors consequently determine a considerable complexity of use and immediate functionality.

Aim of the invention The main aim of the present invention is consequently to provide an implantable system of very small dimensions that will enable atrial defibrillation and will be simple to manage by the operator both as regards its encumbrance and as regards its optimized and more immediate functionality.

Description of the invention

The problems listed above are solved by an implantable RF defibrillator according to Claim 1. Further advantageous aspects are defined in the dependent claims. For a better understanding of the subject of the present invention reference will be made to the attached Figures 1 and 2, wherein: Figure 1 illustrates an implantable RF coil with stimulation electrode; and

Figure 2 illustrates an external apparatus with RF output antenna.

The implantable defibrillator according to the present invention consequently comprises:

- an implantable RF coil 10 equipped with a circuit 30 for generating the stimulation signal and with a stimulation electrode 20; and

- an external apparatus 2 with RF output antenna coupled to the coil 10 for transmission of the desired type of stimulation.

The stimulation electrode is directed in the atrium for a low-energy defibrillation, of between 5 and 10 joule. Said coil will receive the energy transmitted by the external apparatus (Figure 2) reconstructing the modality of low-energy atrial defibrillation.

The reception coil 10 is equipped with a stimulation-signal-forming circuit 30, thanks to which said signal is sent to the stimulation electrode 20.

The second component is constituted by the external apparatus with RF output antenna 1 that can be coupled with the implanted one (Figure 1), to which it is possible to transmit the desired type of stimulation. The apparatus may set the functions that are deemed necessary so as to be able to perform interventions of atrial defibrillation. The apparatus can operate either asynchronously or synchronously with the QRS signals detected on the patient. Said apparatus is also equipped with an input for ECG.

hi the development of this apparatus various features may be added that might prove important such as Holter functions, display functions, functions of storage of the cardiac activity, etc.

Thanks to the present device, with the simple implantation of a coil with one stimulation electrode a universal instrument of intervention is obtained that is not perceived by the patient but has a wide application for the cardiologist, who will be able to intervene and defibrillate the atrium in all the cases in which a low-energy atrial defibrillation is able to solve a particular situation. The present RF internal defibrillator hence transfers the possibility of intervention to the external operator, who, by analysing the cardiac activity of a patient, will be able to choose the mode of intervention verifying in real time the outcome of the intervention.