Page 146 - Computational Modeling in Biomedical Engineering and Medical Physics

Electrical activity of the heart 135

specific to hemodynamic events associated with the heart cycle, for example, at times
t B 0.55 s and t B 0.85 s.
The analysis of hemodynamic elements through the fluid circuit twin provides
information about measuring blood pressure, or estimates the DPW and RPW by
solving the companion ODE models.
The cardiac electrical activity is macroscopically manifested as action potentials that
propagate in a synchronized manner. The tuning parameters introduced by the outlin-
ing models proposed to present them may raise concerns on their physical justification
hence usage. It is the penalty that has to be accepted for using homogenization techni-
ques needed for using continuous, homogenized media. Even so, numerical modeling
on detailed “avatar physics” of the actual electrophysiologic processes may have the
merit to render the cardiac cells behavior under normal and abnormal conditions. This
behavioral prototype may be used to provide the additional information needed to
optimize the inversion techniques that aim to predict the cardiac electric activity out
of measurements performed on the body surface (the EEG inverse problem), to assist
the medical staff in the analysis of complex cardiac problems and to optimize existing
pacing or defibrillation methods.
The electric activity of the heart triggers the mechanical activity of the hemodynamic
system, whose state is its reflection. Noninvasive methods aim to qualify and quantify the
vascular system state, which may be used, in turn, to assert the cardiac state. This complex
electromechanical interaction may suggest a “holistic” approach in modeling cardiovascu-
lar interactions and processes—from the triggering excitable cardiac tissue to the pulse
pressure wave response and the associated feedback. Here and not the least, the hemody-
namic system and flow may be well presented through analogue, twin electric circuits,
which facilitate their mathematical modeling and synthesis.

References
Agabiti-Rosei, E., Mancia, G., O’Rourke, M.F., Roman, M.J., Safar, M.E., Smulyan, H., et al., 2007.
Central blood pressure measurements and antihypertensive therapy. A consensus document.
Hypertension 50, 154 160.
Aguilar, M., Nattle, S., 2016. The pioneering work of George Mines on cardiacarrhythmias: ground-
breaking ideas that remain influentialin contemporary cardiac electrophysiology (symposium review).
J. Physiol. 594 (9), 2377 2386.
Akhmediev, N., Soto-Crespo, J.M., Town, G., 2001. Pulsating solitons, chaotic solitons, period doubling,
and pulse coexistence in mode-locked lasers: complex Ginzburg-Landau equation approach. Phys.
Rev. E 63.
Aliev, R.R., Panfilov, A.V., 1996. A simple two-variable model of cardiac excitation. Chaos Soliton.
Fract. 7 (3), 293 301.
Alonso, S., Bär, M., Panfilov, A.V., 2013. Negative tension of scroll wave filaments and turbulence in
three-dimensional excitable media and application in cardiac dynamics. Bull. Math. Biol. 75,
1351 1376.
Applanation Tonometry, 2020. Mayo Clinic ,https://www.mayoclinic.org/tests-procedures/eye-exam/
multimedia/applanation-tonometry/img-20006176..