Implantable device for cardiac vector determination
An implantable electrostimulation device having at least three input channels, (each forming a sensing channel), which are each connected to at least one electrode or to one terminal for an electrode, using which at least three different electrical potentials accompanying an excitation of cardiac tissue (myocardium) in a heart may be detected. Uses a signal processing unit which is connected to the input channels and is implemented to analyze the time curve of the potentials detected via the three sensing channels as three input signals in chronological relation to a periodically repeating trigger signal, which triggers a time window, and which is also implemented to detect predefined signal features for each of the three input signals within the time window triggered by the trigger signal, store them, and compare them to corresponding signal features of preceding time windows or of another input channel within the same time window.
1. An implantable electrostimulation device comprising:
at least one electrode or one terminal for an electrode;
at least three input channels, which are each connected to said at least one electrode or one terminal for an electrode, wherein said at least three input channels are configured to detect at least three different electrical potentials that accompany an excitation of cardiac tissue in a heart, wherein said at least three input channels form at least three sensing channels;
memory configured to store data;
a signal processing unit connected to said at least three input channels wherein said signal processing unit is configured to
analyze a time curve of potentials detected via said at least three sensing channels as three input signals in chronological relation to a periodically repeating trigger signal, which triggers a time window;
detect predefined signal features for each of said three input signals within said time window triggered by said periodically repeating trigger signal;
determine either a maximum amplitude value for each of said three differential signals or a time offset in said time window of said maximum amplitude value for each of said three differential signals;
calculate one summation vector per cardiac cycle for said three input signals within said time window triggered by said periodically repeating trigger signal using either said maximum amplitude value for each of said three differential signals or said time offset in said time window of said maximum amplitude value for each of said three differential signals;
store said one summation vector per said cardiac cycle in said memory; and
compare said one summation vector to
a corresponding summation vector of a preceding time window,
determine a change in angle between said summation vector and said summation vector of said preceding time window.
2. The implantable electrostimulation device according to claim 1 wherein said signal processing unit is further configured to
compare a detected current signal feature of an input signal in regard to an instant of an occurrence of a shape feature in said time window to an instant of an occurrence of a corresponding shape feature in another input signal or in a preceding time window.
3. The implantable electrostimulation device according to claim 1 wherein said signal processing unit is further configured to
detect an instant of an occurrence of an amplitude maximum in said time window as a signal feature.
4. The implantable electrostimulation device according to claim 1 wherein said signal processing unit is further configured to
detect an instant of an occurrence of said signal feature in relation to a duration of said time window.
5. The implantable electrostimulation device according to claim 1 wherein said signal processing unit is further configured to
derive a trigger signal from one of said three input signals in such a way that said trigger signal is triggered by a signal feature of said one of said three input signals.
6. The implantable electrostimulation device according to claim 5 wherein said signal processing unit is further configured to
derive said trigger signal from said input signal which represents a near field potential.
7. The implantable electrostimulation device according to claim 5 wherein said implantable electrostimulation device has
a fourth input channel as a fourth sensing channel, which is connected to another at least one electrode or one terminal for an electrode, wherein said fourth input channel is configured to detect a near field of an electrical potential that accompanies an excitation of said cardiac tissue in said heart, and
wherein said signal processing unit is further configured to
derive said trigger signal from an input signal of said fourth sensing channel.
8. The implantable electrostimulation device according to claim 7 wherein
said at least three sensing channels are far field channels and are each connected to an electrode or a terminal for an electrode, wherein said far field channels are configured to detect a far field of an electrical potential that accompanies said excitation of said cardiac tissue in an operating state of said implantable electrostimulation device, and
wherein said fourth sensing channel is a near field channel, which is connected to an electrode or to a terminal for an electrode, wherein said fourth sensing channel is configured to detect said near field of said electrical potential that accompanies said excitation of said cardiac tissue in said operating state of said implantable electrostimulation device.
9. The implantable electrostimulation device according to claim 6 wherein said input signal that represents said near field potential is detected via a near field channel, to which at least one bipolar, right-ventricular electrode line is connected or is to be connected, which has a ventricular ring electrode and a ventricular tip electrode, via which said near field potential is detected.
10. The implantable electrostimulation device according to claim 1 wherein said signal processing unit comprises a loop recorder configured to record input signal sections and wherein said signal processing unit is further configured to
perform detection of said predefined signal features in said time window, which begins before an occurrence of a trigger signal, triggered by said trigger signal.
11. The implantable electrostimulation device according to claim 1 wherein said signal processing unit has a signal template memory and is further configured to
detect said predefined signal features on a basis of a comparison of a particular input signal to a stored signal template.
12. The implantable electrostimulation device according to claim 1 wherein said at least three input channels are far field channels, which are each connected to an electrode or to a terminal for an electrode, wherein said far field channels are configured to detect a far field of an electrical potential that accompanies said excitation of said cardiac tissue in an operating state of said implantable electrostimulation device, so that an input signal that represents a particular far field is applied to said at least three input channels.
13. The implantable electrostimulation device according to claim 12 wherein said electrostimulation device is configured as an implantable cardioverter/defibrillator, and, of said far field channels, a first is connected to an electrode formed by a housing of said implantable cardioverter/defibrillator and a terminal for a proximal defibrillation electrode or atrial shock electrode, a second input channel is connected to an electrode formed by said housing of said implantable cardioverter/defibrillator and a terminal for a distal defibrillation electrode or ventricular shock electrode, and a third input channel is connected to a terminal for a distal defibrillation electrode and said terminal for a proximal defibrillation electrode.
14. The implantable electrostimulation device according to claim 12 wherein said signal processing unit is further configured to
analyze differential signals detected via said three far field channels in regard to absolute value and sign of their maximum amplitude value in comparison to one another.
15. The implantable electrostimulation device according to claim 12 wherein said signal processing unit is further configured to
derive an electrocardiogram from each of said differential signals received via each two far field channels.
16. The implantable electrostimulation device according to claim 15 wherein said signal processing unit is further configured to
derive three electrocardiograms from those differential signals which originate from three different input channels, respectively from pairs of input channels selected from said three different input channels.
17. The implantable electrostimulation device according to claim 16 wherein said signal processing unit is further configured to
determine a particular maximum deflection in an area of a QRS complex as a signal feature for each electrocardiogram.
18. The implantable electrostimulation device according to claim 16 wherein said electrostimulation device has a memory, in which an angle value is stored for each of said differential signals or said electrocardiograms, wherein said signal processing unit is connected to said memory and wherein said signal processing unit is further configured to analyze said particular maximum amplitude of said particular differential signal or an amplitude of said particular electrocardiogram together with an associated angle value.
19. The implantable electrostimulation device according to claim 18 wherein said signal processing unit is further configured to
analyze maximum amplitudes of said differential signals or maximum deflections of said electrocardiograms as vector components of said summation vector and to
determine and analyze a direction of said summation vector.
20. The implantable electrostimulation device according to claim 19 wherein said signal processing unit is further configured to
derive said summation vector as an Einthoven summation vector from said maximum deflections of three different electrocardiograms at an instant of an R wave of a particular cardiac cycle.
21. The implantable electrostimulation device according to claim 18 wherein said signal processing unit is further configured to
determine said direction of said summation vector anew for every cardiac cycle.
22. The implantable electrostimulation device according to claim 21 wherein said signal processing unit works together with said memory for at least said direction of said summation vector for at least one preceding cardiac cycle and is further configured to
detect a change of said direction of said summation vector beyond a predefined minimum amount.
23. The implantable electrostimulation device according to claim 22 wherein said signal processing unit is further configured to
detect a change of said direction of said summation vector for more than one cardiac cycle.
24. The implantable electrostimulation device according to claim 22 wherein said signal processing unit is further configured to
analyze an input signal that characterizes a near field in regard to signal peaks that each characterize a ventricular contraction.
25. The implantable electrostimulation device according to claim 24 wherein said signal processing unit is further configured to
analyze a chronological interval of said signal peaks in regard to a heart rate or an RR interval.
26. The implantable electrostimulation device according to claim 24 wherein said signal processing unit is further configured to
derive a marker signal from said signal peaks.
27. The implantable electrostimulation device according to claim 26 wherein said signal processing unit is further configured to
determine an amplitude of a differential signal or said electrocardiogram for each cardiac cycle at an instant of a particular marker signal and to
analyze amplitudes thus obtained as absolute values of components of said summation vector to determine a direction of said summation vector.
28. The implantable electrostimulation device according to claim 25 wherein said electrostimulation device has a tachycardia classification unit, which is connected to said signal processing unit and is configured to classify a ventricular tachycardia through analysis of RR intervals or RR rate and said absolute value and sign of said maximum amplitude values of said differential signals or said absolute value and sign of said amplitudes of said electrocardiograms.
29. The implantable electrostimulation device according to claim 25 wherein said electrostimulation device has a tachycardia classification unit, which is connected to said signal processing unit and is configured to classify a ventricular tachycardia through analysis of a direction of said summation vector and RR intervals or RR rate.
30. The implantable electrostimulation device according to claim 1 wherein said electrostimulation device has a stimulation success detection unit, which is connected to said signal processing unit and is configured to
detect a stimulated contraction of a heart chamber on a basis of said absolute value and sign of said maximum amplitude values of said differential signals or said absolute value and sign of said amplitudes of said electrocardiograms and
assign said stimulated contraction to said heart chamber.
31. The implantable electrostimulation device according to claim 19 wherein said electrostimulation device has a stimulation success detection unit, which is connected to said signal processing unit and is configured to
detect a stimulated contraction of a heart chamber through analysis of said direction of said summation vector and
assign said stimulated contraction to said heart chamber.