You may have seen this on TV: Someone whose heart has gone into a wildly abnormal rhythm, or whose heart has stopped, is shocked when a medic uses defibrillator paddles to restart the heart.
The electric shock is so powerful that the body convulses and the patient screams. You can see it on YouTube if you search for “defibrillator shock.” The video makes clear what patients go through, including those who have defibrillators implanted in their hearts.
Aydin Babakhani, an engineering professor at the University of California, Los Angeles, likens implantable defibrillators to dial up telephones, which have long since been replaced by smartphones.
“Pacemakers use a very old technology. They still use wires. They still use batteries. And they are bulky and large,” he said.
New ways for the heart
Babakhani places tiny sensors on very small chips for industrial and medical use. Before his move to UCLA, he worked at Rice University, where he began collaborating with Dr. Mehdi Razavi, a cardiologist at the Texas Heart Institute.
The men were investigating new ways to pace and defibrillate the heart. The collaboration was easy because Rice is across the street from the heart institute.
As a cardiac electrophysiologist, Razavi wants to be able to shock the heart back into a normal rhythm without shocking the patient. Razavi says the idea of placing a number of small chips in the heart could achieve that goal.
“The limitation up to now with using pacing is that we simply do not have enough pacing sites to distribute this energy across the heart muscle,” he said.
Babakhani developed small chips to pace the heart and help it stay in a normal rhythm. They are smaller than a dime, less than 18 millimeters long. This pacing system has no battery and no leads, the wires that connect the battery to the heart in traditional pacemakers.
Traumatic, painful event
Even when there’s no pain, defibrillation has a huge impact.
When John O’Leary’s implanted defibrillator sent shocks to his heart to get it back into a normal rhythm, it stopped him cold.
“I thought I walked into a lamp post,” he said. “There was no pain whatsoever. I really felt that I walked into something hard.”
Razavi says another problem with the pacemaker/defibrillators now in use is that once patients are defibrillated, many of them feel traumatized. It can take more than one shock to get the heart back into a normal rhythm.
Anne Bunting said she screamed in pain through repeated defibrillations.
“It saved my life that day, but it was also a fearsome thing to go through because it was so painful,” she said.
Preclinical trials promising
In preclinical trials, the chips worked well. “We did a test with six simultaneous chips all over the heart and they were all pacing together,” Babakhani said.
Babakhani and Razavi are now working on a delivery system that will not require surgery. The goal is to thread the chips into the heart on a catheter, much like doctors implant stents by placing them on a catheter and threading it through a vein in the groin.
The chips would be powered by microwaves. A slim generator would be placed under the skin, and the chips could be placed in multiple locations in the heart. This would eliminate the need to replace the pacemaker’s battery, and it eliminates the weakest part of a traditional pacemaker, which is the lead.
Razavi likens the generator that will power the chips to a symphony and its conductor.
“You have 30 chips in the heart, so you have 30 members of the symphony. This power generator, under the skin is the conductor, and it orchestrates simultaneously, in unison, it commands all those chips, and those chips follow its command,” he said.
What’s more, the shock would be distributed throughout the heart.
“By doing that you do not feel a shock. You do not feel anything,” Razavi said.
The men estimate that it will take them five more years to bring the technology for pacemakers to a level on par with that of smartphones.