4,757,815
1 2
pies of the present invention, this envelope corresponds HEART PACEMAKER to the respiration signal.
Two successive QRS complexes 4 and 5 are shown BACKGROUND OF THE INVENTION enlarged in FIG. 2 having different amplitudes. As
1. Field of the Invention 5 shown in FIG. 2, a measurement is undertaken for each The present invention relates to heart pacemakers, complex from the most positive point to the most nega
and in particular to heart pacemakers which vary the tive Point of the R wave, with the respective distances
output pulse rate based on respiration activity of the 6 311(1 7 between the peak values being the measure of
user. the respiration signal used in the present invention.
2. Description of the Prior Art 10 A schematic circuit diagram for a heart pacemaker Heart pacemakers are known which employ a respi- for operating based on the measurement principles deration signal obtained from the user of the pacemaker to scribed above is shown in FIG. 3. The pacemaker is vary the repetition rate of the pulses generated by the encapsulated in a housing 8 and comprises a pulse genpacemaker. Such pacemakers are described, for exam- erator 9 for generating heart pacing pulses which are pie, in U.S. Pat. No. 3,593,718 and in European patent 15 conducted to a heart 10 via an electrode line 11 having application No. 00 89 014. These known heart pacemak- an electrode tip 12 introduced in the heart 10. The paceers use an impedance pneumograph for acquiring a maker further includes an amplifier 13 for the incoming respiration signal. Such an impedance pneumograph heart action signals acquired by the electrode line 11. requires additional electrodes and energy for impe- The amplifier 13 is followed by a peak sensing means 14 dance measurement. 20 for QRS complexes including a first sample/hold ele
SUMMARY OF THE INVENTION ment 15a for positive peaks and a second sample/hold
element 15b for negative peaks.
It is an object of the present invention to provide a The acquired peak values are supplied through a heart pacemaker which varies the output pulse repeti- multiplexer 16 and an analog-to-digital converter 17 to tion rate in dependence upon a respiration signal from 23 a difference fonner 18. The difference former 18 forms the pacemaker user in a simple manner with low energy a signal corresponding to the differences between the consumption. acquired positive and negative peaks for each QRS
In accordance with the principles of the present in- ,ex ^ sj ^ of the difference former 18
vention, the above object is achieved m a pacemaker ig Ued tQ ... ^ w a k&tion si ^ for havmg a pulse generator, a respiration signal measuring *i ^ ^
taker. The control unit 19 controls the means, and control means for controlling the pulse , r . „ . , ... „ . ,
. , . , .... ° . c pulse generator 9 via a control line 20 so that the pulse
generator by modifymg the pulse repetition rate thereof tl. , ■ >• ,
dependent on the ration signal The pacemaker has "Pf'T rate ,of the pacmg Pulsfs 18 ...
a heart action detector for acquiring a heart action sig- smfted from a !ower Pacm/ ^te toward higher pacing
nal, and the respiration signal measuring means includes 35 rates with an mcreasmg frequency of the respiration
means for determining amplitude fluctuations in the ^ ■* the 0UtPut °f the difference former 18. The
heart action signal and supplying a signal corresponding ?aculS frequency is thus appropriately adapted to the
to those fluctuations to the control unit as the respira- ^creasing requirements of the pacemaker user m a sim
tion signal. Ple manner.
The respiration signal in the pacemaker disclosed 40 Although modifications and changes may be sugherein can thus be directly acquired from fluctuations of gested by those skilled in the art it is the mtention of the the heart action signal. An additional current for mak- inventors to embody within the patent warranted ing an impedance measurement is thus not required and hereon all changes and modifications as reasonably and no extra electrode is needed. The pacemaker is thus properly come within the scope of their contribution to technically simpler to construct and consumes less en- 45 the art. ergy to operate. We claim as our invention:
1. A heart pacemaker comprising: DESCRIPTION OF THE DRAWINGS pulse generator means for generating heart pacing
FIG. 1 is a schematic illustration of heart action sig- pulses; nals and their amplitude fluctuations from which a res- 50 means for acquiring a heart action signal from said piration signal can be derived. heart having amplitude fluctuations therein which
FIG. 2 is an enlarged portions of successive heart vary according to respiratory activity of the pace
action signals of the type shown in FIG. 1 and illustrates maker user;
the measuring principle employed by the pacemaker respiration signal measuring means for measuring said disclosed herein. 55 amplitude fluctuations and generating a respiration
FIG. 3 is a schematic block circuit diagram of a heart signal therefrom; and
pacemaker constructed in accordance with the princi- control means connected to said pulse generator pies of the present invention. means and to said respiration signal measuring
nuc^DTimmi /->=• Tuc ... means for changing the rate of said heart pacing
DESCRIPTION OF THEPREFERRED ^ signals generated by said pulse generator means in EMBODIMENTS response to said respiration signal.
A series of heart action signals 1 is shown in FIG. 1 2. A heart pacemaker as claimed in claim 1, wherein which are acquired by a heart pacemaker in a conven- said respiration signal measuring means comprises a first tional manner, such as by means of a QRS detector. The peak value sensor for sensing positive fluctuations and a amplitudes 2 (R waves) thereof are subject to fluctua- 65 second peak value sensor for sensing negative fluctuations caused by the respiration cycle of the user of the tions in said heart action signal, a difference former heart pacemaker. The envelope for all such fluctuations connected to the outputs of said first and second peak is referenced 3 in FIG. 1. In accordance with the princi- value sensors, said difference former measuring the
