Surgery: light – thermal – and electrical application – Light – thermal – and electrical application – Electrical therapeutic systems
Reexamination Certificate
2001-07-25
2004-06-08
Sykes, Angela D. (Department: 3762)
Surgery: light, thermal, and electrical application
Light, thermal, and electrical application
Electrical therapeutic systems
C607S009000, C607S014000
Reexamination Certificate
active
06748267
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a heart therapy device. More specifically, the invention relates to an automatically implantable cardioverter/defibrillator (AICD) or a combined demand pacemaker/AICD.
2. Related Art
Automatic heart therapy devices are generally known and of daily medical use—particularly and for a longer period of time as implantable heart pacemakers for the treatment of bradycardiac and/or tachycardiac arrythmiae, but also increasingly as automatic defibrillators or cardioverters, combined pacemakers/defibrillators or as implantable drug dosing pumps, and the like.
Generic devices are also particularly known, which are equipped with one or more sensor(s) for sensing the cardiac rhythm in the patient's body, associated signal processing and editing means, and an evaluation and control unit. The latter calculates in each case an actual parameter or set of parameters in accordance with an algorithm stored in the device, depending on the value or the values of the heart rate from the amount of programmed operational parameters or therapy values. Therapy devices of said kind are known, which are configured for an automatic actuation or—a pre-programmed—switch-over from one operational mode into another depending upon the cardiac rhythm sensed in the patient's body. Such devices include the known demand heart pacemakers or automatic defibrillators, and the combination devices developed in recent times.
As early as the development and clinical application of so-called demand pacemakers, it has been known to specifically control heart pacemakers such that spontaneous cardiac actions are sensed, and the value of the heart rate or of the time intervals between determined heart actions (e.g. the RR intervals between successive ventricle actions) are assessed and compared with a predetermined nominal value, and that the pacemaker outputs stimulation pulses exactly at the moment, when the measured value is not within the range defined by the nominal value.
More modem devices of this type are microprocessor-controlled and offer the possibility of an individual, tailor-made programming for specific clinical symptoms from a plurality of pre-installed operational modes, by means of which and of associated operational parameters (in the following also called therapy values, as far as these are therapeutically relevant), a predetermined therapy is realized.
Within this framework, essential further developments of the concept of the demand pacemaker to the universal demand heart rhythm correction device have taken place, some of them starting from an increasingly refined subdivision of ranges of the heart rate continuum or RR interval continuum and which, depending upon which of the plurality of predetermined ranges the actual measured value lies, one of a plurality of defined therapies in each case definitely allocated to one range, is realized. By means of such a device, classical demand pacemaker operation in the case of bradycardia can be realized as well as conventional therapies of various tachycardiae (cf. for example U.S. Pat. No. 4,181,133) or, if necessary, even a defibrillation shock therapy (cf. U.S. Pat. No. 4,300,567).
Because the sole allocation of the heart rate to a predetermined range does not always reliably allow for a determination of the adequate therapy, additional classification criteria have been increasingly tested in the developments of the past years, and have been taken into account with the control algorithms; Such an example can be found in U.S. Pat. No. 5,379,776 (including the therein quoted sources).
Devices of the aforementioned kind are programmed on the occasion of implantation according to the clinical symptoms and, in some cases, to the living conditions (e.g. the average physical activities) of the patient, whereby the algorithm to be applied is also fixed for determining the therapy or the therapy value(s) in dependence of t he value(s) sensed in the body. At the time of regular aftercare examinations taking place at determined intervals, the set of operational modes and parameters, as well as—in case the therapy device disposes of several stored algorithms—the control algorithm to be applied can be modified by reprogramming.
U.S. Pat. No. 5,354,316 discloses a method and an apparatus for detecting and treating tachycardiae and fibrillations of a heart by means of specifically selected therapies of a combined pacemaker-cardioverter-defibrillator (PCD) apparatus of the generic kind. U.S. Pat. No 5,354,316, uses mutually overlapping range limits between tachycardia and fibrillation heart rate ranges. The assessment of the actually detected heart rhythm—in case of elevated heart rates—in the area of the ventricular tachycardia or of the ventricular fibrillation, ensues in the overlapping ranges by means of additional assessment criteria. It is specifically examined how many of the preceding intervals between successive ventricle actions fall into the overlapping range.
U.S. Pat. No. 5,447,519 discloses a similar method, whereby as a differentiation criterion between a ventricular tachycardia and ventricular fibrillation, the variability of the heart signal morphology (ECG curve profile) is referred to.
Another generic device is described in the Applicant's DE 196 09 362 C1. This heart therapy device likewise defines an overlapping region between two adjacent value ranges of a value measured in a patient's body. For controlling a selected, predetermined therapy, this device generally takes an evaluation of the history of the measurable variable (specifically the range allocation of the respective preceding value) or even of the therapy control value itself as the basis, in case the value is within the overlapping range.
OBJECTS OF THE INVENTION
It is an object of the invention to provide an improved therapy device of the generic kind, having a relatively simple and cost-efficient structure and yet being able to provide for an utmost careful but simultaneously efficient therapy of tachycardiac arrythmiae bordering on fibrillations—in particular in case of an atrial tachycardia.
SUMMARY OF THE INVENTION
The above and other objects of the invention can be solved by a heart therapy device. The heart therapy device includes a heart rate detection means for detecting a heart rate, an evaluation and control means coupled to the output of the heart rate detection means, the evaluation and control means having an output and being adaptable to evaluate a measured heart rate, including allocating the measured heart rate to one of a first, second and third heart rate value ranges, and output a therapy control signal in accordance with said allocation. The evaluation and control means includes a three-area memory for storing the first, second, and third heart rate value ranges, the heart rate value ranges ascending incrementally in value; a heart rate discriminator coupled to the heart rate detection means and the three-area memory for allocating a measured heart rate to the first, second or third heart rate value range, and for outputting a corresponding first, second or third discriminator output signal; a stability evaluation means for outputting a stability output signal and evaluating heart rate stability over a predetermined period of time in response to the output of the second heart rate discriminator output signal; and a logical processing unit for processing the second discriminator output signal and the stability output signal and for generating a second or third therapy control signal, while the first and third discriminator output signal are directly outputted as first and third therapy control signal, respectively. The heart therapy device also includes a therapy means coupled to the output of said evaluation and control means for realizing at least one therapy having a predetermined therapy parameter in response to the therapy control signal, in accordance with the measured heart rate lying within one of the predetermined value ranges, the therapy means being adaptable to ou
Nigam Indra B.
Shekhar Mrigank
Thong Tran
Biotronik Mess-und Therapiegeraete GmbH & Co.
Bradford Roderick
Kinberg Robert
Sykes Angela D.
Venable LLP
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