Technology Review: Heartbeats at the Speed of Light: "Artificial pacemakers normally use electrodes to deliver regular, 'paced' electrical impulses to the heart muscle to keep its beats consistent. While the devices are safe in the short term, they can cause damage to the muscle if used over decades. The technique's intrusive methods--which require contact with the heart --also limit its capabilities as a research tool.
'If you're trying to use an electrode to touch the heart and stimulate it, the contacts could disrupt potential observation of the heartbeat,' says Ed Boyden, a professor of biological engineering at MIT. Boyden was not involved in the research. 'A noninvasive methodology for pulsing the heart is important for science. Potentially, this could open up a lot of experiments.'"