![](bg5.png)
when reference waveforms of blood flow and
pressure are considered (Figure 7). As can be seen,
higher R
1
and R
2
magnitudes produce higher
pressure gradient along the stenosis, reflected in an
increased output voltage. In a similar way, as
expressed in eq. 3 formula, worse obstruction
conditions produce higher pulmonary artery
pressures, as expected according to medical reports
about stenosed arteries (Rothman, Perry, Keane and
Lock, 1990).
Figure 7: Output mean value of the system for R
1
and R
2
parameter sweep.
5 CONCLUSIONS
For the last forty years, several implantable
electronic devices with flow sensing and wireless
communication capabilities have been developed
and tested, but their power consumption, dimensions
and long-term reliability in such a hostile
environment as human body remain as unsolved
drawbacks. For this reason, a simplified model of an
implantable device for pulmonary artery blood flow
measurement based on pressure sensing has been
developed. This kind of devices present some
important advantages, such as its dual pressure and
blood flow velocity sensing capabilities, together
with an improved robustness and reliability
compared with the rest of the analyzed measurement
methodologies. Finally, different possible grades of
stenosis in the artery have been simulated, by
varying the obstruction geometry parameters
between ranges reported by medical studies, in order
to obtain a first approximation of the device
behaviour under real conditions.
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BEHAVIOURAL ANALYSIS OF AN IMPLANTABLE FLOW AND PRESSURE SENSING DEVICE
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