EE 5340/7340, SMU Electrical Engineering Department, © 20051 Electrocardiogram (ECG) n Generated in...
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EE 5340/7340, SMU Electrical Engineering Department, © 2005 1 Electrocardiogram (ECG) Generated in the heart amplitude range: 0.5 - 4 mV frequency range: 0.01-250 Hz measurement: surface electrodes
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Transcript of EE 5340/7340, SMU Electrical Engineering Department, © 20051 Electrocardiogram (ECG) n Generated in...
EE 5340/7340, SMU Electrical Engineering Department, © 2005 1
Electrocardiogram (ECG)
Generated in the heart amplitude range: 0.5 - 4 mV frequency range: 0.01-250 Hz measurement: surface electrodes
2 EE 5340/7340, SMU Electrical Engineering Department, © 2005 2
Structure of Heart heart chambers
r. atrium, l. atrium r. ventricle, l. ventricle
heart valves tricuspid (RA:RV) Mitral (LA:LV) semilunar (RV:pulm. art.) aortic (LV:aorta)
EE 5340/7340, SMU Electrical Engineering Department, © 2005 3
Structure of Heart (cont.)
RA
RV
sup. vena cava
pulmonary art.
LA
LV
lungs
pulmonary v.
aorta
coronary arteries
coronary sinus
EE 5340/7340, SMU Electrical Engineering Department, © 2005 4
Conductive Tissues in Heart
sino-atrial (SA) node internodal tracts AV node Bundle of His Purkinje fibers
} atria
} ventricles
EE 5340/7340, SMU Electrical Engineering Department, © 2005 5
Cardiac Cycle
venous blood enters LA, passes through TC valve to RV RV contracts, TC valve closes. pulm. valve opens, blood goes to lungs via pulm. art. blood enters LA through pulm. vein, passes through open
mitral valve to LV LA contracts, mitral valve closes, aortic valve opens,
blood goes to aorta. 2 atria contract nearly simultaneously (RA contracts a bit
earlier) 2 ventricles contract simultaneously.
EE 5340/7340, SMU Electrical Engineering Department, © 2005 6
Cardiac Output and Chamber Pressures
typically 5 l/min 70-80% total blood volume in veins 20% in arteries remainder in capillaries systolic (max) pressure: 95-140 mm Hg (120 average) diastolic (min) pressure: 60-90 mm Hg (80 average) LV: 130/5 mm Hg (sys/dias) LA: 9/5 mm Hg RV 20/5 mm Hg RA: 3/0 mm Hg
EE 5340/7340, SMU Electrical Engineering Department, © 2005 7
Electrocardiogram Features
P
Q
R
S
T
0.6s
P: atrial depolarization QRS: ventricular depolarization T: ventricular repolarization
typical heart rate: 72 BPM
EE 5340/7340, SMU Electrical Engineering Department, © 2005 8
Lead Configurations for ECG Measurement
Bipolar Leads Augmented Leads Chest (V) Leads
EE 5340/7340, SMU Electrical Engineering Department, © 2005 9
Bipolar Leads: lead I
+ _
vo
+
_
EE 5340/7340, SMU Electrical Engineering Department, © 2005 10
Bipolar Leads: lead II
+ _
vo
+
_
EE 5340/7340, SMU Electrical Engineering Department, © 2005 11
Bipolar Leads: lead III
+ _
vo
+
_
EE 5340/7340, SMU Electrical Engineering Department, © 2005 12
Augmented Leads: aVR
+ _
vo
+
_
EE 5340/7340, SMU Electrical Engineering Department, © 2005 13
Augmented Leads: aVL
+ _
vo
+
_
EE 5340/7340, SMU Electrical Engineering Department, © 2005 14
Augmented Leads: aVF
+ _
vo
+
_
EE 5340/7340, SMU Electrical Engineering Department, © 2004 15
Unipolar Chest Leads
v1 v2
v3
v4
v5 v6
v1: fourth intercostal space, at right sternal margin. v2: fourth intercostal space, at left sternal margin. v3: midway between v3 and v4. v4: fifth intercostal space, at mid clavicular line. v5: same level as v4, on anterior axillary line. v6: same level as v4, on mid axillary line.
EE 5340/7340, SMU Electrical Engineering Department, © 2004 16
Unipolar Chest Leads (cont.)
+ _ +
_
EE 5340/7340, SMU Electrical Engineering Department, © 2004 17
ECG Lead Color Codes
C (brown)
LA (black)
LL (red)RL (green)
RA (white)
EE 5340/7340, SMU Electrical Engineering Department, © 2004 18
Surface Cardiac Potentials
taken at t = to suggests an equivalent dipole located within the heart
EE 5340/7340, SMU Electrical Engineering Department, © 2004 19
Eindhoven’s Triangle
-very crude solution to inverse problem using bipolar limb leads:
RA LA
LL
_
_
+
_
++
lead II
lead I
lead III
EE 5340/7340, SMU Electrical Engineering Department, © 2004 20
Abnormal ECG Rhythms
Complete Heart Block (AV Block): -atria and ventricles contract independently
P P P P
+
=
RT T TRR
P
R
T P
RT P
EE 5340/7340, SMU Electrical Engineering Department, © 2004 21
Abnormal ECG Rhythms (cont.)
First Degree AV Block: increased AV node delay, get increased P-R intervals.
Second Degree Block: get one QRS complext for every two P waves.
heart block can be treated with drugs, artificial pacemakers.
P PP
R
T
EE 5340/7340, SMU Electrical Engineering Department, © 2004 22
Ectopic Focus PVC’s
Ectopic Focus: region of ischemic cardiac tissue that becomes injured, depolarizes spontaneously, may cause an entire ventricular contraction:
PVC
also called extrasystole
EE 5340/7340, SMU Electrical Engineering Department, © 2004 23
Tachycardia (Rapid Heart Rate)
ectopic focus can also discharge repeatedly producing ventricular (paroxysmal) tachycardia:
all QRS complexes
if etopic focus is located in atrium, can get atrial flutter:
P P P P P
R R
P P P P
EE 5340/7340, SMU Electrical Engineering Department, © 2004 24
Tachycardia (Rapid Heart Rate)
ectopic focus can also discharge repeatedly producing ventricular (paroxysmal) tachycardia:
all QRS complexes
if etopic focus is located in atrium, can get atrial flutter:
P P P P P
R R
P P P P
