Active implantable medical device of the multisite type

Details Active implantable medical device of the multisite type Active implantable medical device of the multisite type

1999-02-11

2001-01-30

Jastrzab, Jeffrey R. (Department: 3762)

Surgery: light, thermal, and electrical application

Light, thermal, and electrical application

Electrical therapeutic systems

Reexamination Certificate

active

06181968

ABSTRACT:

FIELD OF THE INVENTION
The present invention concerns “active implantable medical devices” such as those devices defined by the Jun. 20, 1990 directive 90/385/EEC of the European Community Council, more particularly devices which are able to deliver to the heart electrical impulses of low energy (stimulation impulses) for the processing of troubles of the cardiac rhythm such as cardiac pacemakers, defibrillators and/or cardiovertors. It more particularly concerns the so-called “multisite” prostheses, that is to say prostheses in which electrodes are placed in a plurality of distinct respective sites on the heart, typically with at least two ventricular sites.
Such a multisite cardiac prosthesis can be of the type known as “double chamber” (double ventricular stimulation), triple chamber (right atrial stimulation and double ventricular stimulation) or quadruple chamber (double atrial stimulation and double ventricular stimulation).
BACKGROUND OF THE INVENTION
It is known to treat troubles of the cardiac rhythm (arrhythmias) with cardiac stimulation. It also has been proposed to treat troubles of the myocardium contraction observed in patients with cardiac insufficiency (hereinafter “troubles”) with cardiac stimulation. These latter troubles can originate spontaneously or can be induced by a traditional cardiac stimulation impulse. Reference is made to the study of J. C. Daubert et al.,
Stimuœur
, Volume 25, n°3, pp. 170-176 (1997) which describes the state of the art on this subject. It has already been proposed to stimulate simultaneously the right and left ventricles, which is known as a “double stimulation”. This technique also can be applied to a double stimulation of the atria (i.e., the left and right atria).
One of difficulties of the known multisite stimulation is to guarantee the efficiency of the stimulation on the different cardiac sites. In particular, one generally observes different stimulation thresholds between the right site and the left site. This can result in a defective (e.g., insufficient) stimulation or an erroneous depolarization wave detection (i.e., confusion between an electro-stimulated depolarization originating at the one site and an indirectly sensed depolarization having its origin at the neighboring site). The latter is sometimes called a “far-field” detection.
French patent FR 2 680 093 and its corresponding U.S. Pat. No. 5,411,533, commonly owned by the assignee of this invention, describe a device provided with an automatic adjustment of the stimulation impulse amplitude in relation to a determined capture threshold. This adjustment is obtained by a progressive reduction of the stimulation impulse amplitude level over several successive cardiac cycles, detection of the disappearance of the capture, and then reestablishment of the stimulation impulse amplitude at a level slightly greater than the threshold corresponding to the disappearance of capture. The disclosure of U.S. Pat. No. 5,411,533 is incorporated herein by reference.
As is generally understood by persons skilled in the art, “capture” is a cardiac event where there is a depolarization following and responsive to delivery of a stimulation impulse. The “capture threshold” is the minimal voltage level of the stimulation impulse that causes capture, namely the desired depolarization of the cardiac tissue at the stimulation site.
OBJECTS AND SUMMARY OF THE INVENTION
It is an object of the present invention, therefore, to remedy to this difficulty, by providing an automatic adjustment of the of stimulation impulse amplitude of the neighboring sites, e.g., the left site and the right site, in relation with the “capture threshold”, that is to say the minimal level of voltage amplitude allowing for a capture on the considered site.
To this end, the invention broadly proposes an active implantable medical device of the aforementioned multisite type, that is to say in which electrodes are respectively placed at least two neighboring cardiac sites. Preferably, the two neighboring cardiac sites are either (1) at least one site in the right ventricle and one site in the left ventricle (also called the “right and left ventricular sites”), or (2) at least one site in the right atrium and one site in the left atrium (also called “the right and left atria sites”) or (3) both (1) and (2).
These electrodes are respectively connected to one or more circuits for sensing the cardiac signal in order to detect a depolarization potential on the corresponding site(s), and to one or more stimulation circuits to apply, if necessary, a stimulation impulse on the same site(s). The device also comprises means to determine a capture threshold, and means to adjust the stimulation impulse amplitude in relation to the capture threshold, and means to fix a total refractory period comprising an absolute refractory period during which all detection is inhibited, followed by a relative refractory period.
According to the present invention, the detection of a depolarization during the relative refractory period marks the absence of a capture (also called a “loss of capture”).
Very advantageously, it is foreseen to provide a means to adjust the instant of the beginning of the relative refractory period, preferably by a progressive increase of the relative refractory period duration over several successive cardiac cycles, until there is a detection of a depolarization in this relative refractory period, without any modification of the duration of the total refractory period.
Preferably, the duration of the total refractory period is constant and the initial duration of the relative refractory period is null (zero).
It also can be foreseen to provide a means of preliminary detection of the absence of extrasystolic activity, and to condition the implementation of the means for adjusting the stimulation amplitude on the detected absence of extrasystolic activity. The preliminary detection means preferably comprises means to evaluate the maximal time of synchronous depolarization of the two neighboring sites, namely the two ventricular sites and/or the two atrial sites.
Finally, to avoid a false detection, the device advantageously optionally comprises means for detecting a “bigeminy” condition, which is able to inhibit the adjustment of the stimulation impulse threshold, even in case of the detection of a depolarization during the relative refractory period.


REFERENCES:
patent: 5411533 (1995-05-01), Dubreuil et al.
patent: 5564430 (1996-10-01), Jacobson et al.
patent: 5601615 (1997-02-01), Markowitz et al.
patent: 5800465 (1998-09-01), Thompson et al.
patent: 5871508 (1999-02-01), Thompson et al.
patent: 0 479 215 (1992-04-01), None
patent: 0 653 225 (1995-05-01), None
patent: WO 86/05698 (1986-10-01), None
patent: WO 9604956 (1996-02-01), None
J.C. Daubert, et al.; “Quel avenir pour la stimulation comme traitement primaire de l'insuffisance cardiaque?”,Stimuvoeur, 1997, vol. 25, issue 3, pp. 170-176.

Affiliated with

Also associated with

Rating

Active implantable medical device of the multisite type does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Active implantable medical device of the multisite type, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Active implantable medical device of the multisite type will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2557676