Elsevier

Heart Rhythm

Volume 8, Issue 9, September 2011, Pages 1482-1491
Heart Rhythm

Regular issue
Experimental
Single-sensor system for spatially resolved, continuous, and multiparametric optical mapping of cardiac tissue

https://doi.org/10.1016/j.hrthm.2011.03.061Get rights and content
Under a Creative Commons license
open access

Background

Simultaneous optical mapping of multiple electrophysiologically relevant parameters in living myocardium is desirable for integrative exploration of mechanisms underlying heart rhythm generation under normal and pathophysiologic conditions. Current multiparametric methods are technically challenging, usually involving multiple sensors and moving parts, which contributes to high logistic and economic thresholds that prevent easy application of the technique.

Objective

The purpose of this study was to develop a simple, affordable, and effective method for spatially resolved, continuous, simultaneous, and multiparametric optical mapping of the heart, using a single camera.

Methods

We present a new method to simultaneously monitor multiple parameters using inexpensive off-the-shelf electronic components and no moving parts. The system comprises a single camera, commercially available optical filters, and light-emitting diodes (LEDs), integrated via microcontroller-based electronics for frame-accurate illumination of the tissue. For proof of principle, we illustrate measurement of four parameters, suitable for ratiometric mapping of membrane potential (di-4-ANBDQPQ) and intracellular free calcium (fura-2), in an isolated Langendorff-perfused rat heart during sinus rhythm and ectopy, induced by local electrical or mechanical stimulation.

Results

The pilot application demonstrates suitability of this imaging approach for heart rhythm research in the isolated heart. In addition, locally induced excitation, whether stimulated electrically or mechanically, gives rise to similar ventricular propagation patterns.

Conclusion

Combining an affordable camera with suitable optical filters and microprocessor-controlled LEDs, single-sensor multiparametric optical mapping can be practically implemented in a simple yet powerful configuration and applied to heart rhythm research. The moderate system complexity and component cost is destined to lower the threshold to broader application of functional imaging and to ease implementation of more complex optical mapping approaches, such as multiparametric panoramic imaging. A proof-of-principle application confirmed that although electrically and mechanically induced excitation occur by different mechanisms, their electrophysiologic consequences downstream from the point of activation are not dissimilar.

Keywords

Arrhythmia
Electrophysiology
Fluorescence
Mechano-electric coupling
Optical mapping

Abbreviations

AP
action potential
[Ca2+]i
intracellular free calcium
CaT
Ca2+ transient
EMCCD
electron-multiplied charge-coupled device
LED
light-emitting diode
UV
ultraviolet
Vm
membrane potential

Cited by (0)

Peter Lee and Christian Bollensdorff are joint first authors. This work was supported by the United Kingdom (UK) Biotechnology and Biological Sciences Research Council, the British Heart Foundation (BHF), the European Commission VPH-preDiCT grant, and the National Institutes of Health (NIH Grant R01 EB001963). Peter Lee is a PhD student at the University of Oxford and in receipt of a Clarendon Scholarship. Dr. Alex Quinn holds a Postdoctoral Fellowship from the UK Engineering and Physical Sciences Research Council. Dr. Peter Kohl is a Senior Fellow of the BHF.