Ex Parte Gunderson et al

Patent Trial and Appeal Board

Nov 25, 2013

11564132 (P.T.A.B. Nov. 25, 2013)

UNITED STATES PATENT AND TRADEMARK OFFICE
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BEFORE THE PATENT TRIAL AND APPEAL BOARD
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Ex parte BRUCE D. GUNDERSON, MARK L. BROWN, and
AMISHA SOMABHAI PATEL1
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Appeal 2011-010834
Application 11/564,132
Technology Center 3700
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Before TONI R. SCHEINER, ERIC GRIMES, and
JEFFREY N. FREDMAN, Administrative Patent Judges.

GRIMES, Administrative Patent Judge.

DECISION ON APPEAL
This is an appeal under 35 U.S.C. § 134 involving claims to a method
of processing data generated by an implantable medical device, which have
been rejected for obviousness. We have jurisdiction under 35 U.S.C. § 6(b).
We reverse.

1 Appellants identify the Real Party in Interest as Medtronic, Inc. (Appeal
Br. 3).
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STATEMENT OF THE CASE
The Specification states that increasing amounts of time are required
to review data generated by implantable medical devices, such as
implantable cardioverter-defibrillators (ICDs), and therefore “an algorithm
that post-processes and automatically reviews each previously detected
episode upon interrogation could address these concerns by accurately
classifying episodes and potentially suggesting ICD parameter changes
and/or medical therapy, such as changes in medication” (Spec. 2, ¶ 4).
The Specification provides “a flowchart of classifying of a cardiac
event” (id. at 3, ¶ 10; Fig. 3). One of the steps in the algorithm is re-
classifying a cardiac event as either a supraventricular tachycardia event or a
VT/VF event (id. at 7, ¶ 24). “[T]his re-classification of the detected event
is made by determining an A/V ratio associated with the ratio of atrial
sensed events to ventricular sensed events over a predetermined window of
sensed events occurring prior to the detection of the [cardiac] event” (id.).
Claims 1, 3-5, 7, and 8 are on appeal. Claim 1 is illustrative and reads
as follows (emphasis added):
1. A method of post-processing of sensing data generated by and
stored within an implantable medical device, comprising:
receiving the sensing data from the implantable medical device
with an external access device, wherein the sensing data includes sensed
atrial events and sensed ventricular events;
determining, with the external access device, in response to the
received data, instances where the implantable medical device identified a
cardiac event being detected in response to the sensing data; and
determining, with the external access device, a ratio of sensed
atrial events to sensed ventricular events in response to the received data,
wherein determining the ratio comprises:
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defining a window of the sensing data associated with the
identified cardiac event being detected, the window including
only sensing data occurring prior to and including the cardiac
event being detected; and
determining a number of sensed atrial events and a
number of sensed ventricular events in the window.

DISCUSSION
The Examiner has rejected claims 1, 3, 5, and 7 under 35 U.S.C.
§ 103(a) as obvious based on Gunderson2 and Sheth3 (Answer 44). The
Examiner has rejected claims 4 and 8 under 35 U.S.C. § 103(a) as obvious
based on Gunderson, Sheth, and Murphy5 (Answer 5). The same issue is
dispositive for both rejections.
The Examiner finds that “Gunderson discloses the claimed invention
except . . . determining a ratio of sensed atrial events to sensed ventricular
events in response to the transmitted data” (id.). The Examiner finds that
“Sheth teaches that atrial flutter can be determined by measuring the ratio of
sensed atrial events to ventricular events (e.g. ¶46). Sheth further discloses
that it determines if the atrial to ventricular events are a 1:1 ratio[ ] (e.g.
¶¶46-48).” (Id.) The Examiner concludes that it would have been obvious
“to modify Gunderson to include the analysis of atrial to ventricular
conduction, as taught by Sheth, to provide the predictable results of

2 Gunderson et al., US 2003/0204215 A1, issued Oct. 30, 2003.
3 Sheth et al., US 2005/0080347 A1, issued Apr. 14, 2005.
4 The statement of the rejection in the Answer includes only claims 1 and 5
(Answer 4) but the Examiner made clear elsewhere that the rejection applies
to claims 1, 3, 5, and 7 (id. at 2). Appellants recognized that the rejection
applies to claims 1, 3, 5, and 7 (Appeal Br. 6).
5 Murphy et al., US 5,379,776, issued Jan. 10, 1995.
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discriminating electrical conduction abnormalities and identifying when
Wenchebach conduction is occurring which is a potentially fatal condition”
(id.).
Appellants argue that “Sheth describes determining a ratio of
measured lengths of intervals, rather than numbers of events, to determine
an atrial to ventricular ratio” (Appeal Br. 8). Appellants argue that Sheth
discloses “comparing the measured lengths of intervals” (id.) and that
“[m]erely comparing measured R-R intervals to measured P-P intervals in
some manner is not the same as determining a number of sensed atrial events
and a number of sensed ventricular events within [a] window, as required by
claim 1” (id. at 9).
We agree with Appellants that the Examiner has not shown that the
cited references would have made obvious a method that includes
determining a ratio of sensed atrial events to sensed ventricular events by
“determining a number of sensed atrial events and a number of sensed
ventricular events” occurring within a window of sensing data, as required
by claim 1.
The Examiner concedes that Gunderson does not disclose the disputed
limitation, but finds that Sheth does (Answer 5). Sheth discloses “a method
for discriminating atrial flutter from atrial fibrillation” (Sheth 2, ¶ 14). “The
atrial flutter/atrial fibrillation discrimination method involves applying
multiple atrial arrhythmia detection criteria based on atrial rate, atrial cycle
length regularity, ventricular cycle length regularity and/or ventricular cycle
length” (id. at 2, ¶ 15).
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Sheth discloses that “[a]trial flutter is distinguished from atrial
fibrillation by regular ventricular cycle lengths or ventricular cycle lengths
that correspond to a multiple of the atrial cycle length indicating, for
example, 1:1, 2:1 or 3:1 conduction of atrial flutter waves to the ventricles”
(id. at 2, ¶ 16). Sheth discloses that “[a]trial fibrillation is distinguished
from atrial flutter by irregular ventricular cycle lengths showing no
correspondence to atrial cycle lengths” (id.).
In Sheth’s method, “ventricular cycle length variability, e.g., the R-R
interval . . . may be measured as the difference between the maximum and
minimum R-R intervals” (id. at 5, ¶ 44). “If the ventricular cycle lengths are
determined to be regular during the elevated atrial rate . . . , the atrial rhythm
is classified as atrial flutter” (id. at 5, ¶ 46). If the ventricular cycle lengths
are not determined to be regular but “measured R-R intervals are
approximately equal to measured P-P intervals or a whole multiple of
measured P-P intervals, atrial flutter is indicated” (id.). However, “[i]f the
ventricular rhythm is independent of the atrial rhythm, . . . atrial fibrillation
is detected” (id. at 5-6, ¶ 49).
Thus, Sheth measures the variability in ventricular cycle length during
a given time period and expressly provides for irregular cycle lengths. Since
the length of the ventricular cycles – and therefore the number of
contractions – during the measurement period can vary, the length of
ventricular cycles measured by Sheth does not provide an indirect count of
the number of ventricular contractions during the period.
We therefore do not agree with the Examiner’s reasoning that “even if
the system of Sheth determined the ratio using the length of the intervals, the
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system would still be counting the events” (Answer 7). The example
provided by the Examiner assumes that the lengths of the P-P and R-R
cycles are related (id.) but Sheth expressly discloses that atrial fibrillation is
indicated by a “ventricular rhythm [that] is independent of the atrial rhythm”
(id. at 5, ¶ 49); i.e., the ventricular cycle length (R-R) can be irregular and
unrelated to the atrial cycle length (P-P). Thus, we agree with Appellants
that “comparing measured R-R intervals to measured P-P intervals in some
manner is not the same as determining a number of sensed atrial events and
a number of sensed ventricular events within [a] window, as required by
claim 1” (Appeal Br. 9).
The rejection of claims 1, 3, 5, and 7 as obvious based on Gunderson
and Sheth is reversed. The Examiner’s rejection of claims 4 and 8 as
obvious based on Gunderson, Sheth, and Murphy relies on the same
reasoning discussed above, and is reversed for the same reason.
SUMMARY
We reverse both of the rejections on appeal.

REVERSED

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