Surgery: light – thermal – and electrical application – Light – thermal – and electrical application – Electrical therapeutic systems
Reexamination Certificate
1999-11-12
2002-12-17
Jastrzab, Jeffrey R. (Department: 3762)
Surgery: light, thermal, and electrical application
Light, thermal, and electrical application
Electrical therapeutic systems
Reexamination Certificate
active
06496730
ABSTRACT:
Reference is hereby made to the following, commonly assigned, co-pending, U.S. Patent Applications which disclose common subject matter:
Ser. No.09/290,967 filed on Apr. 13, 1999 for DUAL-CHAMBER PACEMAKER WITH OPTIMIZED PVARP FOLLOWING A PVC filed in the names of R. Betzold et al.; Ser. No. 09/067,729 filed Apr. 28, 1998 for MULTIPLE CHANNEL, SEQUENTIAL, CARDIAC PACING SYSTEMS filed in the names of C. Struble et al.; Ser. No. 09/439,569 filed on even date herewith for CARDIAC PACING SYSTEM DELIVERING MULTI-SITE PACING IN A PREDETERMINED SEQUENCE TRIGGERED BY A SENSE EVENT in the names of C. Yerich et al.; Ser. No. 09/439,565 filed on even date herewith for BI-CHAMBER CARDIAC PACING SYSTEM EMPLOYING UNIPOLAR LEFT HEART CHAMBER LEAD IN COMBINATION WITH BIPOLAR RIGHT HEART CHAMBER LEAD in the names of B. Blow et al.; Ser. No. 09/439,078 filed on even date herewith for MULTI-SITE CARDIAC PACING SYSTEM HAVING TRIGGER PACE WINDOW in the names of C. Juran et al.; Ser. No. 09/439,568 filed on even date herewith for RECHARGE CIRCUITRY FOR MULTI-SITE STIMULATION OF BODY TISSUE filed in the names of B. Blow et al.; and Ser. No. 09/439,243 filed on even date herewith for AV SYNCHRONOUS CARDIAC PACING SYSTEM DELIVERING MULTI-SITE VENTRICULAR PACING TRIGGERED BY A VENTRICULAR SENSE EVENT DURING THE AV DELAY in the names of C. Yerich et al.
FIELD OF THE INVENTION
The present invention pertains to multi-site cardiac pacing systems for pacing first and second sites of a patient's heart, particularly right and left heart chambers, e.g., the right and left ventricles, and operable in selected pacing modes while avoiding inappropriate responses to double sensing of an evoked depolarization conducted between the sites.
BACKGROUND OF THE INVENTION
In diseased hearts having conduction defects and in congestive heart failure (CHF), cardiac depolarizations that naturally occur in one upper or lower heart chamber are not conducted in a timely fashion either within the heart chamber or to the other upper or lower heart chamber. In such cases, the right and left heart chambers do not contract in optimum synchrony with each other, and cardiac output suffers due to the conduction defects. In addition, spontaneous depolarizations of the left atrium or left ventricle occur at ectopic foci in these left heart chambers, and the natural activation sequence is grossly disturbed. In such cases, cardiac output deteriorates because the contractions of the right and left heart chambers are not synchronized sufficiently to eject blood therefrom. Furthermore, significant conduction disturbances between the right and left atria can result in left atrial flutter or fibrillation.
It has been proposed that various conduction disturbances involving both bradycardia and tachycardia of a heart chamber could benefit from pacing pulses applied at multiple electrode sites positioned in or about a single heart chamber or in the right and left heart chambers in synchrony with a depolarization which has been sensed at at least one of the electrode sites. It is believed that cardiac output can be significantly improved when left and right chamber synchrony is restored, particularly in patients suffering from dilated cardiomyopathy and CHF.
A number of proposals have been advanced for providing pacing therapies to alleviate these conditions and restore synchronous depolarization and contraction of a single heart chamber or right and left, upper and lower, heart chambers as described in detail in commonly assigned U.S. Pat. Nos. 5,403,356, 5,797,970 and 5,902,324 and in U.S. Pat. Nos. 5,720,768 and 5,792,203 all incorporated herein by reference. The proposals appearing in U.S. Pat. Nos. 3,937,226, 4,088,140, 4,548,203, 4,458,677, 4,332,259 are summarized in U.S. Pat. Nos. 4,928,688 and 5,674,259, all incorporated herein by reference. The advantages of providing sensing at pace/sense electrodes located in both the right and left heart chambers is addressed in the '688 and '259 patents, as well as in U.S. Pat. Nos. 4,354,497, 5,174,289, 5,267,560, 5,514,161, and 5,584,867, also all incorporated herein by reference.
The medical literature also discloses a number of approaches of providing bi-atrial and/or bi-ventricular pacing as set forth in: Daubert et al., “Permanent Dual Atrium Pacing in Major Intra-atrial Conduction Blocks: A Four Years Experience”,
PACE
(Vol. 16, Part II, NASPE Abstract 141, p.885, April 1993); Daubert et al., “Permanent Left Ventricular Pacing With Transvenous Leads Inserted Into The Coronary Veins”,
PACE
(Vol. 21, Part II, pp. 239-245, Jan. 1998); Cazeau et al., “Four Chamber Pacing in Dilated Cardiomyopathy”,
PACE
(Vol. 17, Part II, pp. 1974-1979, November 1994); and Daubert et al., “Renewal of Permanent Left Atrial Pacing via the Coronary Sinus”,
PACE
(Vol. 15, Part II, NASPE Abstract 255, p. 572, April 1992), all incorporated herein by reference.
Problems surface in implementing multi-site pacing in a single heart chamber or in right and left heart chamber pacing within the contexts of conventional timing and control systems for characterizing and responding to sense event signals generated by sense amplifiers coupled to spaced apart pace/sense electrodes. Inappropriate responses can be triggered by depolarizations conducted between the separated pace/sense electrode sites and sensed by sense amplifiers coupled to those pace/sense electrodes which upset the timing of delivery of subsequent pacing pulses. In right and left heart pacing systems, pacing and sensing problems arise when right-to-left or left-to-right conduction delays vary depending on right and left ventricle pace/sense electrode placement, transient conditions of the heart, and chronic CHF.
In modern cardiac pacemakers, it is common to define certain blanking and refractory periods commenced after delivery of a pacing pulse and sensing of a depolarization wave traversing the pace/sense electrode. The input terminals of the sense amplifier are effectively uncoupled from the pace/sense electrodes during the blanking periods following delivery of a pacing pulse. The blanking periods are shorter than refractory periods which are started after both sense events and delivery of pacing pulses.
Sense events detected by a sense amplifier following time-out of a blanking period and during timing out of its refractory periods are characterized as “refractory sense events”, and sense events occurring after time-out of the refractory periods are characterized as “non-refractory sense events”. Non-refractory sense events trigger restarting pacing escape intervals or the AV delay in AV synchronous pacemakers. Refractory sense events restart various post-event time periods including refractory periods as described further below to avoid inappropriate tracking of repetitive noise signals that are mistakenly detected as sense events.
A delivered pacing pulse “captures” the heart if its delivery to a pace/sense electrode causes or “evokes” a myocardial contraction and depolarization wave that is conducted away from that pace/sense electrode site. The depolarization wave and accompanying contraction can be delayed in diseased hearts such that the depolarization wave can be sensed by a sense amplifier coupled to another pace/sense electrode at another site spaced from the paced pace/sense electrode site. The evoked depolarization wave can reach the non-paced pace/sense electrodes after time-out of the post-pace blanking period of the sense amplifier and be sensed during a post-event time period, e.g., a refractory period and be mistakenly characterized as a refractory sense event. The delayed sensing in one or the other of the paced sites can also occur if the pacing pulse delivered at that site fails to capture the heart. The mistakenly characterized refractory sense event restarts post-event blanking and refractory periods. The restarting of these post-event time periods can interfere with the sensing or proper characterization of subsequent true spontaneous depolarizations and disrupt delivery of pacing pulses.
In bi-chamber (bi-atrial or
Betzold Robert A.
Juran Carleen J.
Kleckner Karen J.
Wendell Thomas C.
Yerich Charles G.
Jastrzab Jeffrey R.
Medtronic Inc.
Wolde-Michael Girma
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