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Electric Imaging of Myocardial Ischemia

Electric Imaging of Myocardial Ischemia

Rob MacLeod, Bonnie Punske,Shibaji Shome, Bulent Yilmaz, and

Bruno Taccardi

Cardiovascular Research and Training InstituteBioenginering Department

University of Utah

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OriginsOrigins

OcclusionPre-PTCA Peak-PTCA

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Biophysics of Acute IschemiaBiophysics of Acute Ischemia

0

-80

mV

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Imaging ApproachImaging Approach

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Cardiac Mapping of IschemiaCardiac Mapping of Ischemia

Source of Electrocardiographic ST Changes inSubendocardial Ischemia Li et al. Circ. Res. 82:957-970, 1998

Epicardium

Endocardium

LAD LCx

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Research QuestionsResearch Questions

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

surface?

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Technical ApparatusTechnical Apparatus

• “Andy III”• 370 electrodes• R = 500 cm• Homogeneous• 1024 channel

acquisition

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Isolated Heart PreparationIsolated Heart Preparation

TorsoTank Electrodes

Epicardial Sock Electrodes

Support Dog

Flow Regulators

Heat ExchangeC J

ElectrolyticTorso Tank

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Flow ControlFlow ControlRoller PumpIsolated HeartLeft anterior descending artery

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Epicardial Electrode Sock Epicardial Electrode Sock

• Nylon stocking material

• 490 recording wires• 24 pacing wires• Reference markers

for geometry

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ProtocolsProtocols

• 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

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Signal ProcessingSignal Processing

ToffQon Soff

3/8 5/8

SToff

80ms

ST80

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Tank/Heart GeometryTank/Heart Geometry

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Acute Occlusion

ST

Acute Occlusion

ST

300270240210180150120

906030

30

24

18

12

6

0ml/min s

Flow Time

4Jan01-ocl1

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Graded FlowST

Graded FlowST

30 ml/m

24 ml/m

18 ml/m

12 ml/m

6 ml/m

0 ml/m

10Jan01-ocl1

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Graded Pacing ST80

Graded Pacing ST80

34 ml/m

24 ml/m

18 ml/m

12 ml/m

6 ml/m

0 ml/m

215

190

165

150

130

Flow Heart Rate

10Jan01-ocl4

(reduced flow)

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Fixed Rate, Decreased FlowFixed Rate, Decreased Flow

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

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ReducedFlow:

ST-80

ReducedFlow:

ST-80

19Jan01-ocl1

35

28

21

14

7

0ml/min min

Flow Time

30272421181512

963

33

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ReducedFlow:

ST-80

ReducedFlow:

ST-80

19Jan01-ocl1

35

28

21

14

7

0ml/min min

Flow Time

30272421181512

963

33

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ReducedFlow:

ST-80

ReducedFlow:

ST-80

19Jan01-ocl1

35

28

21

14

7

0ml/min min

Flow Time

30272421181512

963

33

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ReducedFlow:

ST-80

ReducedFlow:

ST-80

19Jan01-ocl1

35

28

21

14

7

0ml/min min

Flow Time

30272421181512

963

33

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ReducedFlow:

ST-80

ReducedFlow:

ST-80

19Jan01-ocl1

35

28

21

14

7

0ml/min min

Flow Time

30272421181512

963

33

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ReducedFlow:

ST-80

ReducedFlow:

ST-80

19Jan01-ocl1

35

28

21

14

7

0ml/min min

Flow Time

30272421181512

963

33

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ReducedFlow:

ST-80

ReducedFlow:

ST-80

19Jan01-ocl1

35

28

21

14

7

0ml/min min

Flow Time

30272421181512

963

33

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ReducedFlow:

ST-80

ReducedFlow:

ST-80

19Jan01-ocl1

35

28

21

14

7

0ml/min min

Flow Time

30272421181512

963

33

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ReducedFlow:

ST-80

ReducedFlow:

ST-80

19Jan01-ocl1

35

28

21

14

7

0ml/min min

Flow Time

30272421181512

963

33

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ReducedFlow:

ST-80

ReducedFlow:

ST-80

19Jan01-ocl1

35

28

21

14

7

0ml/min min

Flow Time

30272421181512

963

33

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ReducedFlow:

ST-80

ReducedFlow:

ST-80

19Jan01-ocl1

35

28

21

14

7

0ml/min min

Flow Time

30272421181512

963

33

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ReducedFlow:

ST-80

ReducedFlow:

ST-80

19Jan01-ocl1

35

28

21

14

7

0ml/min min

Flow Time

30272421181512

963

33

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Fixed Flow, Increased RateFixed Flow, Increased Rate

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

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Increased Rate:ST-80

Increased Rate:ST-80

19Jan01-ocl1

35

28

21

14

7

0ml/min min

Flow Time

200

188

176

167

158

214

231

BPM

Rate

18

15

12

9

6

3

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Increased Rate:ST-80

Increased Rate:ST-80

19Jan01-ocl1

35

28

21

14

7

0ml/min min

Flow Time

200

188

176

167

158

214

231

BPM

Rate

18

15

12

9

6

3

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Increased Rate:ST-80

Increased Rate:ST-80

19Jan01-ocl1

35

28

21

14

7

0ml/min min

Flow Time

200

188

176

167

158

214

231

BPM

Rate

18

15

12

9

6

3

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Increased Rate:ST-80

Increased Rate:ST-80

19Jan01-ocl1

35

28

21

14

7

0ml/min min

Flow Time

200

188

176

167

158

214

231

BPM

Rate

18

15

12

9

6

3

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Increased Rate:ST-80

Increased Rate:ST-80

19Jan01-ocl1

35

28

21

14

7

0ml/min min

Flow Time

200

188

176

167

158

214

231

BPM

Rate

18

15

12

9

6

3

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Increased Rate:ST-80

Increased Rate:ST-80

19Jan01-ocl1

35

28

21

14

7

0ml/min min

Flow Time

200

188

176

167

158

214

231

BPM

Rate

18

15

12

9

6

3

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Increased Rate:ST-80

Increased Rate:ST-80

19Jan01-ocl1

35

28

21

14

7

0ml/min min

Flow Time

200

188

176

167

158

214

231

BPM

Rate

18

15

12

9

6

3