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Novel miniature robot invasively accesses the heart
Heart-mounted robot may pave the way for new, minimally invasive treatment methods applied directly to the epicardium.
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Researchers are evaluating a potentially invasive technology that accesses the epicardial surface of the heart through use of a miniature mobile robot that is passive, lightweight, inexpensive and disposable.
The HeartLander facilitates beating-heart intrapericardial therapies. It is designed to pace lead placement, deliver diagnostic treatments and therapeutic injections and potentially offer a single method for stable and localized sensing and mapping of the heart.
“The heart is a complex, moving 3-D structure of soft tissue and is potentially a big challenge for anyone working in this field,” said Marco A. Zenati, MD, associate professor of surgery and the director of the minimally invasive cardiac surgery program at the University of Pittsburgh. “We designed this organ-mounted robot to adhere to the heart and move on the surface while maintaining contact with the heart itself. We believe it will enable cardiovascular specialists to perform a number of applications on the epicardial surface that currently cannot be performed.”
Inner workings
The current HeartLander prototype is 1 inch long and stabilizes itself on the epicardial surface. It has two suction-padded, vacuum-lined feet at the front and rear of the device that are connected by a flexible rubber midsection. This allows the device to move its way along the epicardial surface of the heart at about half a foot per minute and move together with the beating heart, Zenati told Today in Cardiology. An external pump supplies vacuum pressure for suction and is connected through two lines in the tether. Wire transmission runs through a tether to off board motors for movement.
The physician controls the
device with a joystick and graphical interface, and receives feedback through
magnetic tracking sensors, a miniature video camera and fluoroscopy, according
to Zenati.
The device is inserted into the body through a small incision below the xiphoid process of the sternum, therefore providing direct access to the heart. After incision in the pericardium, the device is placed directly on the epicardium.
Results of proof of concept studies with the HeartLander in animal models have shown successful suction and locomotion on all surfaces of the beating porcine heart through a 25 mm percutaneous incision and 10 mm pericardial incision. The results also show accomplished epicardial lead placement and myocardial dye injections of the porcine heart. Zenati and colleagues did not note any adverse hemodynamic or electrophysiological events or epicardial damage from locomotion.
New advantages
Compared with current minimally invasive cardiac robotics, the HeartLander obviates cardiac stabilization, lung deflation and access limitations, which can result in decreased trauma to the patient and greater efficiency, according to Zenati.
“HeartLander introduces two significant innovations; it is organ mounted and moves with the beating heart and it is deployed through percutaneous access through the subxiphoid approach,” he said.
He explained that entrance of the HeartLander through the subxiphoid provides direct visualization and precision and completely controlled guidance of the device to perform whatever intervention is necessary. Future work will focus on a magnetic tracking system for autonomous navigation.
Additionally, this product may have an economic advantage over currently used robotic tel-operative surgical systems, which cost more than $1 million, because the device itself will be made of single use, disposable plastic. Zenati speculated that the cost for the robot itself, not including cost of the engineering equipment, would be about $100.
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Source: The Robotics Institute at Carnegie Mellon |
“This technology is intriguing,” said Lawrence H. Cohn, MD, Hubbard professor of cardiac surgery at the Harvard Medical School, and the division of cardiac surgery at Brigham and Women’s Hospital and physician director of medical device technology at Partners HealthCare. “It may well have some application, particularly on procedures that don’t go inside the heart, but need to be put on the outside, such as pacemakers, implantable cardioverter-defibrillators and maybe atrial fibrillation procedures.
“There is nothing like this. It is totally innovative and if it really works it will be a winner,” added Cohn, also a member of Today in Cardiology’s editorial board.
Ongoing research
Zenati imagines cardiovascular specialists — specifically interventional cardiologists, interventional electrophysiologists or minimally invasive cardiac surgeons — will use this technology for many possible interventions. It may be deployed for definition and diagnosis of a disease process, remodeling of the ventricle and/or treatment on the outside of the heart, he said.
“I think this technology will allow cardiologists to perform interventions that used to be in the domain of surgeons,” he said. “It will allow interventional cardiologists to expand their expertise in cardiac surgery, and it may eventually form a synergy between the cardiologist and minimally invasive surgeons.”
The researchers are in the beginning phase of a study that will use this magnetic tracking system of the HeartLander to map the surface of the heart among pigs with tachycardia. Eventually they hope to equip the front module of the HeartLander with modular end-effectors to allow for innovative therapies.
One downfall to this technology is that the suction pads have shown to cause some bruises on the surface of the heart, Zenati said, which the researchers plan to further investigate. They have not noted any serious damages to the heart itself.
Based on available literature, Today in Cardiology Fellows Advisory Board Member Uday N. Kumar, MD, believes this may be a technology that precedes the clinical need for it.
“The problem is there are not many procedures performed in the intrapericardial space today, especially by cardiologists” said Kumar, adjunct clinical instructor for the division of cardiovascular medicine at Stanford University School of Medicine. “This device definitely could help deliver some sort of therapy, as the researchers say, but the current clinical need for therapies to be delivered from the intrapericardial space are quite limited.”
Kumar and Cohn both said they would like to see results of large animal trials, specifically ones that prove the efficacy of performing a procedure and delivering a therapy to the heart from the intrapericardial space, establish the validity for its use in practice, define its effects on the heart and compare it to standard methods that are currently available.
“Overall, I don’t think anyone will deny that this is an interesting and innovative technology, but using it routinely is very far off,” Kumar said. “There are a lot of steps in understanding science and clinical needs before we get to that point.” – by Tara Grassia
Dr. Zenati has a direct financial interest in HeartLander.
For more information:
- To learn more about the HeartLander visit: www.cs.cmu.edu/~heartlander/index.html