Effect of optical pacing on action potential upstroke.

<p>Top shows action potential upstrokes normalized to a 100 mV action potential that were recorded within 0.5 mm of the stimulation site, before pacing began (baseline, 0 min) and then after continuous pacing at 5 min, 10 min, 15min, 20 min, and 25 min. Bottom shows maximum dVm/dt during the upstroke for sites within 0.5 mm of the stimulation site (n = 4). No significant differences were observed between baseline (0 min) and all other time points.</p

System validation using Flecainide and Quinidine.

<p>Activation time (top) and APD (bottom) contour maps measured at baseline (left) and after 0.3 μM Flecainide (right) in a single well of a 96-well plate. Mean local conduction velocity and APD for each map are shown below. Site of optical pacing is shown by red spot in activation contours. Flecainide decreased conduction velocity and increased APD. To the right are summary data for mean local conduction velocity (top) and APD (bottom) before (CNTL) and after Flecainide (n = 7, n = 6) and Quinidine (1.0 μM, n = 7).</p

Demonstration of optical pacing and activation recording.

<p>Optical pacing in an hCM monolayer from a single well of a 96-well plate. Top shows an action potential recording (Vm) and a Ca2+ transient recording from a single pixel in separate wells at room temperature (RT). Middle shows action potentials recorded at 34°C with faster pacing rates. Bottom shows an activation map during optical pacing at 0.5 Hz indicating the local time of maximum Vm derivative (dVm/dt) during the action potential upstroke. Vectors superimposed on contours represents local impulse conduction velocity. The laser spot (red, 400 μm) was imaged while temporarily using a visible wavelength to shows the location of pacing.</p

Media 2: Optical stimulation enables paced electrophysiological studies in embryonic hearts

Originally published in Biomedical Optics Express on 01 April 2014 (boe-5-4-1000

Media 1: Optical stimulation enables paced electrophysiological studies in embryonic hearts

Originally published in Biomedical Optics Express on 01 April 2014 (boe-5-4-1000

Measurement of threshold energies for optical pacing.

<p>(A) Assessment of threshold by a search pattern through a fixed number of monolayers, N = 30 total. To compare threshold under different conditions, 50% capture probability was calculated (see text for details). (B) Cell density at three different values (3.1 x 10², 1.0 x 10³ and 2.0 x 10³ cells/mm²), N = 30 for each point. (C) Pulse widths were varied between 5 ms and 40 ms, N = 18 for each point. (D) Spot size was varied between 4 x 10⁻⁴ and 2.9 x 10⁻³ cm², N = 30 for each point. Thresholds required to achieve 50% pacing probability are plotted against radiant exposure per pulse (B, D) and irradiance (C). Error bars reflect the standard error (A) and standard deviation (B-D). In panels C and D, * indicates a statistically significance (p < 0.001) decrease compared to the smallest pulse width and spot size.</p

Comparison between electrical and optical measurements of action potentials.

<p>Comparison of action potential measured using FluoVolt (cyan) and a sharp microelectrode (orange) simultaneously (top) and at a much higher resolution showing the action potential upstroke (middle). All action potential recordings are normalized to a 100 mV amplitude. In both plots, action potentials recorded with FluoVolt and a sharp microelectrode are highly correlated. The action potential upstroke derivative (dVm/dt) for these examples (bottom left) and over all recordings were identical.</p

Media 1: 4D shear stress maps of the developing heart using Doppler optical coherence tomography

Originally published in Biomedical Optics Express on 01 November 2012 (boe-3-11-3022

Media 1: Optical pacing of the adult rabbit heart

Originally published in Biomedical Optics Express on 01 September 2013 (boe-4-9-1626

Visualization 1: Volumetric optical mapping in early embryonic hearts using light-sheet microscopy

Multiplanar reformatting of 4D transmembrane potential datasets. The colored activation wave is overlaid on the grayscale heart tube. Originally published in Biomedical Optics Express on 01 December 2016 (boe-7-12-5120