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Energy
Efficiency: Q-Stim periodically tests impedance
and energy dissipation at the electrode-tissue interface
– the point of contact between its pacing lead
and the patient – and recalibrates pulse generation
accordingly. In this way, uniquely among neurostimulators,
Q-Stim delivers all prescribed stimulation, while expending
only the energy needed to do so. That maximizes energy
efficiency, revolutionizing the state of the art in
pacemaker technology. Until now, pacemakers couldn’t
optimize their signal based on frequent, complete electrical
characterization of the tissue interface, and so generated
excess charge to prepare for a worst-case scenario.
This wasted energy and shortened the lives of both the
battery and the lead. Q-Stim, by contrast, uses proprietary
adaptive technology, based on real-time electrical characterization
of the patient’s tissue, to conserve battery life.
That, in turn, promotes patient safety by reducing the
need to replace pacemakers as they exhaust their power
supplies.
Multi-point pacing also helps maximize energy efficiency
in the Q-Stim system. By imparting neurostimulation
at multiple locations rather than a single point, researchers
have found that they can reduce the charge required
for equivalent effect not only at each point, but also
cumulatively across all points. The reason: Less stimulation
is required to initiate, reinforce, and sustain a physiological
reaction across multiple points, as opposed to triggering
an effect of equivalent breadth and impact from a single
point.
Durability: The Q-Stim generator has been designed
for implantation in a highly resilient, bio-compatible,
low-profile titanium enclosure. Further promoting system
durability, Q-Stim’s pulse delivery system uses
charge balancing – including a biphasic waveform
that alternates positive and negative transmissions,
and a load-shorting switch that eliminates residual
charge – to guard against charge accumulation
at the electrode-tissue interface. This minimizes corrosion
and helps avoid premature lead failure. With these features,
and with the energy-conservation systems that extend
its battery life, Q-Stim has been designed to maximize
time in service. This minimizes the need for device
replacement, promoting patient safety and well-being.
Efficacy: By delivering neurostimulation on multiple
channels, Q-Stim can supplement or entrain the natural
electrical signals that govern many functions and systems
of the human body. In the stomach, for example, Q-Stim
can progressively pace from proximal to distal regions,
helping regulate the gastric slow wave and accelerate
the flow of nutrients in patients who suffer gastroparesis,
or delayed gastric emptying. By reversing this sequence
– pacing from the distal to the proximal stomach
– Q-Stim can promote feelings of fullness or satiety
in patients who suffer obesity, and so help reduce caloric
intake.
Safety: With its capacitively coupled architecture,
Q-Stim separates pulse generation from the electrode-tissue
interface. This prevents over-stimulation. Following
the stimulation profile input by a clinician, Q-Stim
sends a precisely measured charge to a capacitor via
low-power dissipation. The capacitor, in turn, passes
that charge to the lead, entirely out of circuit from
the pulse generator. In this way, the fundamental architecture
of the circuitry is designed to protect the patient.
In a further safety feature, Q-Stim monitors impedance
and energy dissipation at the electrode-tissue interface,
as noted above. If these measures fall outside the limits
set by a clinician, or if they move outside the range
for which the system can compensate, Q-Stim notifies
the patient through the telemetry unit. Such an alert
could indicate a loose electrode, a broken pacing wire,
or a health problem requiring medical attention.
Clinician Feedback and Ease of Use: With its
medical interface, Q-Stim makes it easy for clinicians
to set stimulation parameters in familiar terms. Using
a personal computer and graphical user interface, they
simply key in the desired pulse amplitude, duration,
and frequency, as well as the sequence and timing of
pacing channels. Clinicians then upload these settings
to Q-Stim’s telemetry unit, which encodes and
transmits them to the pulse generator. The Q-Stim generator
calculates the charge needed to achieve the prescribed
stimulation, automatically compensating for impedance
variations at the electrode-tissue interface. The clinician
can govern this compensation by setting an allowable
range of impedance variation.
Even as it provides stimulation, Q-Stim also gathers
information for the clinician on various therapeutic
and functional questions, including patient compliance
and battery life. The Q-Stim generator monitors these
data and transmits them on demand to the telemetry unit,
from which the clinician can download them into a database
on patient health and progress. After evaluating this
feedback, if the clinician wishes to change the prescribed
regimen of neurostimulation, this is easily communicated
to the Q-Stim generator through the medical interface
and telemetry unit.
Patient Ease of Use: Patients may easily activate
Q-Stim through a control button on the telemetry unit.
Alternatively, Q-Stim can be scheduled to deliver stimulation
automatically, at pre-set times, through a real-time
clock in the pulse generator. |
