Safer, more effective way to shock the heart
A new system for shocking a heart back into normal rhythm is designed to both expand a doctor’s options for routing electric current through the heart and to improve the application of pressure to the patient’s body to help treatment succeed.
“Our system is simple,” says team member Sandya Subramanian of Grand Rapids, Mich. “That means clinicians are more likely to use it.”
Subramanian was one of eight Johns Hopkins biomedical engineering undergraduates who worked on the “PrestoPatch” project beginning in the spring of 2012.
Arrhythmia is an erratic heartbeat that, in serious cases, can be fatal. About 14 million people in the United States alone have been diagnosed with some form of arrhythmia, which can include a heartbeat that is too fast, too slow, too early, or out of synch.
When the condition becomes life-threatening, medical teams may have only three to five minutes to jolt the heart back to normal rhythm. The doctor first must choose two of three locations for electrode patches: on the front, side, or back of the patient. Electric current is then shot between the two electrodes, passing through the heart.
If the first shock doesn’t work, present-day patches can’t be moved to a new position that might yield better results.
“When a shock fails, a physician’s options for what to do next are very limited,” says team leader Piyush Poddar. “The usual next step is to increase the energy of the shock, that is, if it’s not already maxed out. But this increases the patient’s risk for burns and death of heart tissue.”
But the PrestoPatch system could be used at the onset of treatment. The team devised an electric switch that would allow a doctor to attach patches to a patient in all three locations, choosing two for the first shock. If that fails, the doctor can quickly flip a switch and change the current’s path through the body without necessarily increasing the energy of the next shock.
The system’s second component addresses excessive transthoracic impedance, a problem that occurs during defibrillation when the patient’s body resists the life-saving current. Doctors now mitigate this crudely, pressing down on a patient’s patch with their fists.
To improve upon this, the students devised a manual compression tool to apply pressure in a safe, standardized way. Lights and an embedded speaker on the tool alert the doctor when the proper pressure is applied and warns if there is too much pressure.
The PrestoPatch system won first place in the undergraduate division of the 2013 national Collegiate Inventors Competition. Team members will use their $12,500 prize money to launch a company and move their invention closer to clinical use.
Source: Johns Hopkins University
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