Transcript Heart Physiology and the Pacemaker (Comparison of voltage

Heart Physiology and
the Pacemaker
Comparison of voltage change data
sets made by the heart with and
without an artificial pacemaker
Erica Bloor
Electronics Spring 2012
Purpose for Research
 Research:
●
Manipulating program of a heart’s pulse by varying:
Cell location
 Cell connectivity
 Number of broken cells
 Cases with an artificial pacemaker

 Purpose:
●
Compare pulses of heart cells with and without an artificial
pacemaker
See how natural pacemakers cells work
 See how an artificial pacemaker affects the heartbeat

●
Results can be used to better understand voltage changes in various
sections of the heart with or without broken cells in order to see if an
artificial pacemaker would be needed.
The Heartbeat
 The heartbeat:
● Electrical current flow makes the
muscles contract
 Pacemaker cells (Sinus Node)
● Cells that specialize in generating
electricity
● Changing charge from positive to
negative and back by Potassium –
Calcium channels
 “Chain Reaction” of electric
charge
●
Cardiac cell’s capability
RC Circuit
 Motion of the heart is like an RC circuit:
dVi (t ) 1
C
 Vi (t )  g i (t )[Vi (t )  Ek ]  I i (t )
dt
R
C: capacitance
V: potential of cell i at time t
R: resistance
I: external current to cell i, at time t
 Charging and discharging
Real vs. Model Heart
Real Heart
Model Heart
The data collected is likely to be different from other data from a
real heart because of the shape difference in plots.
Voltage Change Comparison
 Created plot (mili-second vs. mV) of [odd, even] cells in heart plot
 Comparison of rows 1, 3, 5, 7, and 9
Connectivity
 How well the heart cells “pass along” current
Like the conductance of a circuit
 Changed connectivity from 0.54 to 0.24 and 0.84
●
Broken Cells
 Damaged cells that may affect the efficiency of the heart
 Looked at surround cells before and after damage
● [3, 5], [5, 2], [8,8]
Broken Pacemaker Cells
 If the pacemaker cells are broken along with the
other 3 broken cells, the heart will beat slowly and
erratically.
Artificial Pacemaker
 Case 1: Artificial pacemaker
will aid in the pulsation of
the heart.
 Case 2: A Chaotic fluctuation
added to the artificial
pacemaker will aid in the
pulsation of the heart.

(Addition) In the program there
is a parameter for chaos, labeled
“ka.” It is set to 1.50.

This could be changed depending
on the amount of chaotic
fluctuation needed by the
recipient.
Artificial Pacemaker
 An artificial pacemaker is needed when the heart
beat is abnormally slow or rapid and erratic.
●
Damage from a heart attack, high blood pressure, and too
much alcohol can lead to a lack of oxygen to the heart. When
the heart is strained, the flow of electrical signal is disrupted.
●
Diseases:
Bradycardia
 Atrial Fibrillation
 Heart Failure
 Syncope

Conclusions
 Heart cells function like RC circuit.
 Broken cells (whether pacemaker
or other heart cells) affect the flow
of current through heart,
impacting the heart’s pulse.
 Pacemakers do not cause the
sinus node to create current, but
aid in the time period of the pulse.
References
“How the Normal Heart Works”
http://www.chop.edu/service/cardiac-center/heart-conditions/how-the-normal-heartworks.html

“Improving the beat of heart failure”
http://www.health.harvard.edu/newsweek/Improving_the_beat_for_heart_failure.htm

“Pacemaker”
http://www.heartonline.org/pacemaker.htm

“Pacemakers”
http://www.hrsonline.org/patientinfo/treatments/pacemaker/

“The electrocardiogram – looking at the heart of electricity”
http://www.nobelprize.org/educational/medicine/ecg/ecg-readmore.html

“The Normal Heart”
http://www.hrsonline.org/PatientInfo/TheNormalHeart/

“The Virtual Heart”
http://thevirtualheart.org/
