Dual Optical Mapping of Triggered and Injury-Anchored Arrhythmias in EHTs

Research Applications

Investigate drug-related repolarization changes, triggered activity and structural barriers underlying ventricular-tachycardia-like propagation.

Model & Design

Two human induced pluripotent stem cell-derived cardiomyocyte sources combined with primary human ventricular fibroblasts at a 3:1 ratio in collagen.

Experimental Format

Approximately one-month-old milliPillar tissues; RH-237/Rhod-2 AM mapping at 1 ms and approximately 22 μm resolution.

Model Components

• Component

  Engineered cardiac tissue

  Description

  Two cardiomyocyte sources and primary human ventricular fibroblasts in a collagen tissue anchored at both ends.

• Component

  Pharmacological/electrolyte conditions

  Description

  100 nM E-4031 tests sensitivity; 500 nM E-4031 with 2 mM potassium and 0.5 mM magnesium produces acquired-long-QT-like conditions.

• Component

  Focal structural perturbation

  Description

  A separate cohort is recorded before and within five minutes after focal cryoinjury in standard physiological solution.

Measurements & Endpoints

• APD80, conduction velocity and repolarization heterogeneity
• Voltage–calcium activity and early afterdepolarizations
• Triggered beats, conduction block and wavebreak
• Phase-singularity/rotor occurrence, location and duration

Analysis

Combine regional voltage/calcium traces, activation/repolarization maps and phase analysis. Analyze the pharmacological and paired-injury cohorts separately and interpret durations within the observation window.

Published Evidence

• Study Design

  Compare long-QT-like challenge with controls and examine the combined perturbation by sequential exposure.

  Study Sample

  27 control and 28 treated tissues across six batches; a separate sequential comparison uses six tissues.

  Comparison

  Control versus combined challenge; sequential baseline, reduced electrolytes and reduced electrolytes plus E-4031.

  Finding

  Phase singularities/rotors occurred in 16/28 versus 0/27 tissues; sequential counts were 0/6, 0/6 and 6/6. Median duration across 111 events was approximately 0.4 s.

  Interpretation & Limits

  • The 100 nM sensitivity experiment differs from the 500 nM/electrolyte challenge.
  • Antiarrhythmic-treatment efficacy was not tested.

• Study Design

  An independent cohort is compared before and after focal injury.

  Study Sample

  Ten tissues from two hiPSC-cardiomyocyte sources, each serving as its own pre-injury control.

  Comparison

  Standard physiological solution before versus after focal cryoinjury, without the long-QT pharmacological challenge.

  Finding

  Phase singularities occurred in 7/10 after injury versus 1/10 before. Tracks favored the injury boundary; three rotors persisted for at least 10 s, with some ongoing at recording end.

  Interpretation & Limits

  • An acute localized-cell-loss model without chronic inflammation/fibrosis or ischemia–reperfusion.
  • Two lines, surface-weighted mapping and short recordings limit extrapolation; ongoing-event durations are lower bounds.