IMPROVEMENT IN IMPLANTATIONS FOR CARDIAC STIMULATION BY PACEMAKER

Abstract: Implantation for cardiac stimulation by means of a pacemaker (11) equipped with a rheograph (10) (commercially known as Biorate) also including a radio-frequency receiver (14) for alternative stimulation by means of an external pacemaker and radio-frequency transmitter, the implanted pacemaker (11) and the radio-frequency receiver (14) having a plate (13, 15) in contact with the patient's tissue, the radio-frequency receiver (14) being clamped on a bipolar electrode (12, 12<1>A, 12<1>, 12<1>B) connecting the implanted pacemaker (11) to the heart (CC); with such arrangement, during the normal stimulation by the implanted pacemaker (11) one polarity (negative) of the stimulation signals is transmitted to the heart through one of the conductors (12, 12<1>) of the electrode while the other polarity (positive) closes through the patient's tissue onto the contact plate (13) of the pacemaker (11); the contact plate (15) of the radio-frequency receiver (14) is connected to the rheograph (10) via the free conductor (12<1>A) of the electrode and acts as one pole of the rheograph (10), being the other pole represented by the pacemaker body (13).

Description: IMPROVEMENT IN IMPLANTATIONS FOR CARDIAC STIMULATION BY PACEMAKER This invention relates to artificial cardiac stimulation and more precisely to cardiac stimulation implantations equipped both with a rheograph and a radio-frequency receiver for alternative stimulation supplied by an external radio-frequency transmitter. In the pacemaker commercially known as Biorate, a rheograph capable of sensing the patient's respiratory rate and that accordingly adjusts the artificial stimulation rate, is inserted, in other words, when the respiratory rate is faster the pacemaker increases the stimulation rate and viceversa. The rheograph senses the respiratory rate by sending a weak current through the patient's tissue between an external pole, implanted in the tissue and adequately connected to the rheograph, and the pacemaker external casing acting as second pole. Since the impedance of the patient's tissue varies when the respiratory muscles contract, the rheograph detects such variation and measures the respiratory rate. In the implantations presently in use the electrode connecting the pacemaker to the heart is unipolar and has, clamped on it, the radio-frequency receiver that carries a plate in contact with the patient's tissue. Also the pacemaker has a plate in contact with the patient's tissue, and, both in case of stimulation from the pacemaker and alternative stimulation from the external transmitter, one of the signal polarities (negative) is transmitted by the electrode while the other polarity (positive) closes from the heart onto the contact plates of one or the other device, through the patient's tissue. According to this invention, the electrode utilized in cardiac electro-stimulation implantations of this type is a bipolar electrode; and the radio-frequency receiver is clamped thereon. Consequently the radio-receiver "splits" the electrode into two lengths, a first length comprised between the pacemaker and radio-receiver and a second length comprised between the latter and heart. By this new arrangement, in the normal stimulation, from the implanted pacemaker, as in the devices in use at present, one polarity of the stimulating signals is transmitted through one conductor of the bipolar electrode while the other polarity from the heart will close onto the contact plate of the pacemaker through the patient's tissue. The second conductor of the bipolar electrode can then be used to connect the rheograph to the radio-frequency receiver plate used as the pole external to the pacemaker, thus avoiding the implant in the patient of another foreign element. In a further embodiment the plate is eliminated and replaced by a metal clip clamped on the electrode conductor connected to the rheograph,an electrically connected to this conductor. The invention will now be described in details with reference to the attached drawings, wherein: fig. 1 shows a first embodiment of the invention wherein the electrode connecting the heart to the pacemaker is bipolar in the whole length; fig. 1A shows another embodiment still utilizing a bipolar electrode wherein a metal clip is clamped on one of the electrode conductor; and fig. 2 is a similar view of a third embodiment of the invention wherein only tte length of the electrode comprised between the pacemaker and the radio-frequency receiver is bipolar. According to fig. 1, showing the first embodiment of the invention, electrode 12 connecting pacemaker 11 to the patient's heart CC is bipolar in its whole length. At an intermediate point of electrode 12, the radiofrequency receiver 14 for alternative stimulation is attached. Of the two conductors of electrode 12, the first one indicated with 12' connects directly the negative out put of pacemaker 11 to heart CC while the other conductor is "splitted" in two separate lengths. One length, indicated by 12'A connects rheograph 10 of the pacemaker to contact plate 15 of radio-frequency receiver 14; the other length indicated by 12'B connects pick-up coil 14A of radio-frequency receiver 14 to heart CC. In normal operation, pacemaker 11 will transmit the negative polarity of the stimulating signals through conductor 12' while the positive polarity will close from the heart onto pacemaker plate 13 through the patient's tissue. Nothing changes in case of alternative stimulation wherein the positive polarity of the stimulating signals from the external transmitter and pacemaker is transmitted through conductor 12'B while the negative polarity is still transmitted through the length of the conductor 12' comprised between its connecting point to pick-up coil 14'A, referred to by 16, and heart CC. In the embodiment of fig. IA, the plate of radiofrequency receiver 214 in contact with the patient 15 tissue is eliminated and the external pole of rheograph 210 comprises a metal clip 220 directly clamped on conductor 212'A and electrically connected thereto. Clip 220 is naturally also in contact with the patient's tissue, being the in#sulating jacket of the conductor removed in correspondance with clip 220. Conductor 212'A has a dead and on radio-receiver 214. In operation clip 220 acts as plate 15 of receiver 14 in the embodiment of fig. 1, sensing any variations of the patient's tissue impedance due to the contraction of patients muscles. This embodiment has the further advan tage that the construction of radio-receiver 214 is lighter. The embodiment shown in fig. 2 differs only for the fact that length 112'B of conductor 112, between radiofrequency receiver 114 and the heart, is unipolar. Also in this embodiment, during normal stimulation, plate 115 of radio-frequency receiver 114 is used as a pole of rheograph 110 that correlates the stimulation ra te to the respiratory rate. The negative polarity of the stimulating signals is transmitted to heart CC through conductor 112' while the positive polarity closes onto pacemaker plate 113 through the patient' 5 tissue. For alternative stimulation from an external pacemaker and radio-frequency transmitter, instead, since the length of electrode 112' connecting radioreceiver 114 to heart CC is unipolar, the positive polarity of the stimulation signals will close onto the plate 115 through the patient's tissue. This implies the necessity of inclu ding in radio-frequency receiver 114 a switch 118 magne tically operated from the outside that will switch the connection of plate 115 from the position shown in fig. 2 with continuous lines, wherein plate 115 is connected to rheograph 110, to the position shown with dotted lines, wherein plate 115 is connected to pick-up coil 114. Nothing varies in connection with the negative polarity of the alternative stimulating signals that is still transmitted through the length of electrode 112' comprised between point 116, of connection with pick-up coil 114A, and heart CC.

Claims: CLAIMS 1. A cardiac stimulation implantation by means of an implanted pacemaker equipped with a rheograph and including also a radio-frequency receiver for alternative cardiac stimulation by means of an external pacemaker and radiofrequency transmitter, said implanted pacemaker and radio-frequency receiver being both equipped with a plate in contact with the patient's tissue, characterizedinthat the electrode connecting said pacemaker to the heart and whereupon said radio frequency receiver is clamped in an intermediate position, splitting the electrode in a first and a second length, is bipolar at least in the first lenght thereof comprised between said pacemaker and said radio-frequency receiver, and that one conductor of said first length is utilized to connect said rheograph to said plate of said radio-frequency receiver. 2. The cardiac stimulation implantation of claim 1, wherein said electrode is bipolar in its whole length. 3. The cardiac stimulation implantation of calim 2, wherein said contact plate of the radio-frequency receiver is eliminated, and the conductor connecting said rheograph carries as rheograph external pole a clip clamped thereon that is in electrical contact both with said conductor and the patient's tissue. 4. The cardiac stimulation implantation of claim 1, wherein said second length of the electrode is unipolar and a switch magnetically operated by the outside is inserted in said radio-receiver and has two different positions, in ose of which said switch connects said radio-receiver plate to said rheograph while in the other position said plate is connected to the radio-receiver pick-un coil.

Inventors: DE BELLIS FERRUCCIO, DE BELLIS, FERRUCCIO
Applicants: SBM SOC BREVETTI MEDICINA, S.B.M. SOCIETA BREVETTI PER LA MEDICINA
Application year: 1987
Main classification: A61N1
IPC codes: A61N1