Electric Imaging of Myocardial Ischemia

1
Electric Imaging of Myocardial Ischemia

• Rob MacLeod, Bonnie Punske,
• Shibaji Shome, Bulent Yilmaz, and Bruno Taccardi

Cardiovascular Research and Training
InstituteBioenginering DepartmentUniversity of
Utah
2
Origins
Occlusion
Pre-PTCA
Peak-PTCA
3
Biophysics of Acute Ischemia
4
Imaging Approach
5
Cardiac Mapping of Ischemia
LAD
LCx
Epicardium
Endocardium
Source of Electrocardiographic ST Changes
in Subendocardial Ischemia Li et al. Circ. Res.
82957-970, 1998
6
Research Questions

• ST elevation or (transient) depression?
• Acute occlusion versus graded flow?
• How do ST changes image on the body surface?

7
Technical Apparatus

• Andy III
• 370 electrodes
• R 500 W cm
• Homogeneous
• 1024 channel acquisition

8
Isolated Heart Preparation
Electrolytic Torso Tank
Flow Regulators
Heat Exchange
C
J
Support Dog
Epicardial Sock Electrodes
TorsoTank Electrodes
9
Flow Control
10
Epicardial Electrode Sock

• Nylon stocking material
• 490 recording wires
• 24 pacing wires
• Reference markers for geometry

11
Protocols

• Acute, complete occlusion
• 3-minute duration
• measurements each 30 s
• Graded flow
• 2-minute intervals at each flow rate
• measurement at end of each interval
• Graded heart rate
• constant flow rate
• increase rate in 2-minute intervals
• measurement at end of each interval

12
Data Processing

• Signals (Everett)
• gain correction, windowing, baseline correction
• global fiducials (Qon, Soff, Toff)
• Geometry
• location of sock in tank
• coronaries
• Maps (Matlab, Map3d)
• integrals QRS, QRST, ST, STT, ST80

13
Signal Processing
3/8
5/8
80ms
Qon
Toff
Soff
SToff
ST80
14
Tank/Heart Geometry
15
Acute Occlusion??ST
Flow
Time
30
300
270
24
240
210
18
180
150
12
120
90
6
60
30
0
s
ml/min
4Jan01-ocl1
16
Graded Flow??QRS
30 ml/m
24 ml/m
18 ml/m
12 ml/m
6 ml/m
0 ml/m
10Jan01-ocl1
17
Graded Flow??ST
30 ml/m
24 ml/m
18 ml/m
12 ml/m
6 ml/m
0 ml/m
10Jan01-ocl1
18
Graded Pacing ? ST80
(reduced flow)
34 ml/m
215
24 ml/m
190
18 ml/m
165
12 ml/m
150
6 ml/m
130
0 ml/m
Flow
Heart Rate
10Jan01-ocl4
19
Graded Pacing??ST80
(full flow)
34 ml/m
215
24 ml/m
190
18 ml/m
165
12 ml/m
150
6 ml/m
130
0 ml/m
Flow
Heart Rate
10Jan01-ocl5
20
Fixed Rate, Decreased Flow

• Start flow at 35
• Reduce to 0
• Increase back to 35
• 3 minutes at each flow rate

21
ReducedFlow??ST-80
Flow
Time
35
28
21
14
7
0
ml/min
min
19Jan01-ocl1
22
ReducedFlow??ST-80
Flow
Time
33
35
30
27
28
24
21
21
18
15
14
12
9
7
6
3
0
ml/min
min
19Jan01-ocl1
23
ReducedFlow??ST-80
Flow
Time
33
35
30
27
28
24
21
21
18
15
14
12
9
7
6
3
0
ml/min
min
19Jan01-ocl1
24
ReducedFlow??ST-80
Flow
Time
33
35
30
27
28
24
21
21
18
15
14
12
9
7
6
3
0
ml/min
min
19Jan01-ocl1
25
ReducedFlow??ST-80
Flow
Time
33
35
30
27
28
24
21
21
18
15
14
12
9
7
6
3
0
ml/min
min
19Jan01-ocl1
26
ReducedFlow??ST-80
Flow
Time
33
35
30
27
28
24
21
21
18
15
14
12
9
7
6
3
0
ml/min
min
19Jan01-ocl1
27
ReducedFlow??ST-80
Flow
Time
33
35
30
27
28
24
21
21
18
15
14
12
9
7
6
3
0
ml/min
min
19Jan01-ocl1
28
ReducedFlow??ST-80
Flow
Time
33
35
30
27
28
24
21
21
18
15
14
12
9
7
6
3
0
ml/min
min
19Jan01-ocl1
29
ReducedFlow??ST-80
Flow
Time
33
35
30
27
28
24
21
21
18
15
14
12
9
7
6
3
0
ml/min
min
19Jan01-ocl1
30
ReducedFlow??ST-80
Flow
Time
33
35
30
27
28
24
21
21
18
15
14
12
9
7
6
3
0
ml/min
min
19Jan01-ocl1
31
ReducedFlow??ST-80
19Jan01-ocl1
32
ReducedFlow??ST-80
19Jan01-ocl1
33
Fixed Flow, Increased Rate

• Start flow at 35
• Reduce to 21
• Increase rate

34
Increased Rate??ST-80
Flow
Time
Rate
35
18
231
15
214
28
12
200
21
9
188
14
6
176
7
3
167
0
158
ml/min
min
BPM
19Jan01-ocl1
35
Increased Rate??ST-80
Flow
Time
Rate
35
18
231
15
214
28
12
200
21
9
188
14
6
176
7
3
167
0
158
ml/min
min
BPM
19Jan01-ocl1
36
Increased Rate??ST-80
Flow
Time
Rate
35
18
231
15
214
28
12
200
21
9
188
14
6
176
7
3
167
0
158
ml/min
min
BPM
19Jan01-ocl1
37
Increased Rate??ST-80
Flow
Time
Rate
35
18
231
15
214
28
12
200
21
9
188
14
6
176
7
3
167
0
158
ml/min
min
BPM
19Jan01-ocl1
38
Increased Rate??ST-80
Flow
Time
Rate
35
18
231
15
214
28
12
200
21
9
188
14
6
176
7
3
167
0
158
ml/min
min
BPM
19Jan01-ocl1
39
Increased Rate??ST-80
Flow
Time
Rate
35
18
231
15
214
28
12
200
21
9
188
14
6
176
7
3
167
0
158
ml/min
min
BPM
19Jan01-ocl1
40
Increased Rate??ST-80
Flow
Time
Rate
35
18
231
15
214
28
12
200
21
9
188
14
6
176
7
3
167
0
158
ml/min
min
BPM
19Jan01-ocl1