IMPROVEMENT IN IMPLANTATIONS FOR CARDIAC STIMULATION BY PACEMAKER

Abstract: Implantation for cardiac stimulation by pacemaker including also a radio-frequency receiver (14) for alternative cardiac stimulation by means of an external pacemaker and a radio-frequency transmitter; wherein the radio-frequency receiver (14) is not equipped with the usual plate in contact with the patient's tissues and is clamped on a bipolar electrode (12) connecting the pacemaker to the heart. In this way, the stimulating signals either from the pacemaker (10) or, in alternative, from the external transmitter, are transmitted through this electrode (12), being the pacemaker (10) also insulated and without the external plate in contact with the patient's tissue. As a modification wherein the pacemaker is equipped with the plate in contact with the patient's tissue, the electrode length connecting the pacemaker with the radio-frequency receiver is unipolar while the length of electrode connecting the radio-frequency receiver to the heart remains bipolar.

Description: IMPROVEMENT IN IMPLANTATIONS FOR CARDIAC STIMULATION BY PACEMAKER This invention relates to artificial cardiac stimu¬ lation and more precisely to implantations for cardiac stimulation equipped with a radio-frequency receiver suitable to receive stimulating signals, alternative to those from the pacemaker, transmitted by a radio-frequen¬ cy transmitter external to the- patient, if necessary. Usually, in these implantations, the electrode con¬ necting the pacemaker to the heart is unipolar and a ra¬ dio-f equency receiver is inserted thereon having a pla- te on the outside of its casing that is in contact with the patient's tissues. The pacemaker too has a plate in contact with the patient's tissue and in case of stimulation both from the implanted pacemaker and alternatively from the exter- nal transmitter, one of the polarities of the stimulating signals (normally the negative) is transmitted through the electrode while the other polarity (the positive) is closed from the heart onto the contact plates through the tissue of the patient. This present arrangement has some drawbacks both as regards the pacemaker operation and implant structure, particularly the radio-frequency receiver structure. The drawback in the operation of the present stimu¬ lation implants is the high density of the current trans- mitted through the patient tissue that may induce undesi¬ rable muscular contractions in the patient's torax. The structural drawback is the size of the contact plate of the radio-frequency receiver that cannot be re¬ duced beyond a certain point, therefore limiting the mi- niaturization of the receiving coil. Accordingly is an object of the invention to provi¬ de an improved stimulating implantation of the type in question wherein the afore mentioned drawbacks are over- come by making use of a continuous bipolar electrode whereon a radio-frequency receiver is clamped deprived of the contact plate usually equipping the radio recei¬ vers now in use. This continuous bipolar electrode connects the per- manently implanted pacemaker to the patient's heart. Nevertheless, the electrode of the invention can be utilized also in the case where the implanted pacema¬ ker has the contact plate and such a plate can be utili¬ zed by connecting the pacemaker and the radio-frequency receiver by an unipolar length of electrode, provided that the plate-less receiver is still connected to the heart by a length of bipolar electrode. The invention is described in details with reference to the attached schematic drawings, wherein: fig. 1 schematically shows a cardiac stimulation implantation of the type presently in use; fig. 2 is a similar view of the implantation accord¬ ing to the invention where use is made of a radio-frequen¬ cy receiver and pacemaker deprived of the external con- tact plate; and fig. 3 is a similar view of a second embodiment of the invention, wherein only the radio-frequency receiver is deprived of the contact plate while such a plate equips the pacemaker, and the electrode length comprised between the pacemaker and radioreceiver is accordingly unipolar. As known, cardiac stimulation implantations equipped with a receiving device for alternative stimulation to that of the implanted pacemaker, have presently a large diffusion. These implantations allow a cardiac stimulation al- ternative to that provided by the implanted pacemaker, by utilizing an external pacemaker and transmitter capa¬ ble of transmitting stimulation signals on a precise ra¬ dio-frequency whereon also the receiver is tuned. The receiver is clamped on the continuous electrode that con- nects the pacemaker to the heart and has a plate for the electric contact with the patient's tissue. The stimulating signals picked up by the radio-fre¬ quency receiver are sent to the heart through the elec¬ trode, the positive polarity being closed through the patient's tissue onto the radio-frequency receiver con¬ tact plate. Normally in this type of implantation the pacemaker too has a plate in contact with the patient's tissue and during normal operation the negative polarity of stimu- lating signals is sent by the pacemaker to the heart through the unique conductor of the unipolar electrode, while the positive polarity is closed through the pa¬ tient's tissue onto the pacemaker contact plate. This mode of operation is schematically shown in fig. 1 that illustrates a traditional implantation for cardiac stimulation equipped with a radio-frequency re¬ ceiver for alternative stimulation wherein the negative polarity of the signals generated by pacemaker 1 is sent to the patient's heart CC through electrode 2 while the positive polarity closes from the heart onto the con¬ tact plate 3 through the patient's tissue. This condition of normal operation is shown in fig. 1 by the dotted li¬ nes LL. Also in case of alternative cardiac stimulation pro¬ vided by signals generated by an external pacemaker (not shown) and transmitted through radio-frequency waves to the receiver 4, the picked-up signals (negative polarity) are sent to the heart CC through unipolar electrode 2A connecting the heart to the receiver 4, while the positi¬ ve plarity closes from the heart onto external plate 5 of receiver 4 through the patient's tissue. This condition is shown in fig. 1 by the continuous lines NN. In other words, in these implantations, both in normal stimulation mode and during alternative stimu¬ lation from outside by radio-frequency signals, the pa- tient's tissues are utilized as earth return; as mention¬ ed this represents a drawback because there is the possi¬ bility of passage of high density currents through said tissues that may cause bothersome and undesirable muscu¬ lar contractions. Moreover the necessity of utilizing a contact plate 5 of suitable dimensions prevents the reduction of the size of the receiver. These drawbacks are completely overcome by the im¬ provement of the invention according to which the exter- nal contact plates of both the pacemaker and radio- frequency receiver are eliminated. This condition is represented in fig. 2 wherein the pacemaker 10 is no longer equipped with the external pla¬ te in contact with the patient's tissue and is connected to heart CC through a bipolar electrode 12. Also the radio-frequency receiver 14 is deprived of the external plate in contact with the patient's tissue and its two outputs for the two polarities of the alter¬ native stimulation signals are connected to the two con¬ ductors of bipolar electrode 12 whereupon receiver 14 is clamped. In both cases of normal and alternative stimulation the two polarities of the stimulating signals are trans¬ mitted to heart CC each through a separate conductor, thus eliminating the necessity of transmitting high-den- sity current pulses through the patient's tissue. Fig. 3 illustrates a modification of the invention wherein the radio-frequency receiver has no contact pla¬ te while the pacemaker is still equipped with such a pla¬ te in contact with the patient's tissue. in this embodiment of the invention, pacemaker 110 is of a type normally available on the market and its external plate 113 is in contact with the patient's tis¬ sue. Accordingly therein, the length of electrode 112 between pacemaker 110 and radio-frequency receiver 114 is unipolar, while the length of electrode 112A between the radioreceiver and the heart is bipolar. During normal operation of pacemaker 110 the nega¬ tive polarity of the stimulating signals is transmitted to heart CC through one of the conductors of bipolar electrode 112A while the positive polarity will close onto plate 113 through the patient's tissue. Nothing changes, in respect to the embodiment of fig. 2, in case of alternative stimulation by the exter¬ nal radio-frequency pacemaker; in fact also in this em¬ bodiment the polarities of the stimulating signals picked up by the radioreceiver will be transmitted to the pa¬ tient's heart through the bipolar length of electrode 112A.

Claims: CLAIMS ' 1. A cardiac stimulation implantation through pace¬ maker including an electrode connected to the patient's heart, equipped with a radio^frequency receiver for al¬ ternative stimulation by an external pacemaker and radio- frequency transmitter, wherein the radio-frequency re¬ ceiver is clamped on said electrode, characterized in that said radio-frequency receiver is deprived of the exter¬ nal plate and said electrode is bipolar at least in the length comprised between said radio receiver and the pa¬ tient's heart. 2. The cardiac stimulation implantation of claim 1, wherein also said pacemaker is deprived of the external plate in contact with the patient's tissue, and said electrode is continuous and bipolar in its whole length.

Inventors: DE BELLIS FERRUCCIO, DE BELLIS, FERRUCCIO
Applicants: SBM SOC BREVETTI MED
Application year: 1987
Main classification: A61N1
IPC codes: A61N1