A research team from the University of Bonn has succeeded for the first time in using light stimuli to stop life-threatening cardiac arrhythmia in mouse hearts. Furthermore, as shown in computer simulations at Johns Hopkins University, this technique could also be used successfully for human hearts. The study opens up a whole new approach to the development of implantable optical defibrillators, in which the strong electrical impulses of conventional defibrillators are replaced by gentler, pain-free light impulses.

Ventricular fibrillation! When the heart muscle races and no longer contracts in an orderly fashion, sudden death often follows due to the lack of blood circulation. In such an emergency, a defibrillator helps to restore normal heart activity by means of intense electrical shocks. In patients with a known risk for these arrhythmia, the prophylactic implantation of a defibrillator is the treatment of choice. If ventricular fibrillation is detected, a pulse of electricity is automatically generated, which normalizes the excitation of the heart muscle and saves the person’s life.

‘When an implanted defibrillator is triggered, which unfortunately can also happen because of false detection of arrhythmia, it is always a very traumatic event for the patient’, says the head of the study, Junior-Professor Philipp Sasse of the Institute of Physiology I at the University of Bonn. ‘The strong electrical shock is very painful and can even damage the heart further’. Therefore, Professor Sasse’s team investigated the principles for a pain-free, gentler alternative. As the scientists have now shown, ventricular fibrillation can be stopped by optical defibrillation.

The team used the new method of ‘optogenetic’ stimulation of mouse hearts, which had genes inserted for so-called channelrhodopsins. These channels are derived from a green algae and change the ion permeability of heart cell membranes when illuminated. When the researchers triggered ventricular fibrillation in the mouse heart, a light pulse of one second applied to the heart was enough to restore normal rhythm. ‘This is a very important result’, emphasizes lead author Dr. med. Tobias Brugmann of Professor Sasse’s team. ‘It shows for the first time experimentally in the heart that optogenetic stimulation can be used for defibrillation of cardiac arrhythmia’. It also worked in normal mice that received the channelrhodopsin through injection of a biotechnologically-produced virus. This shows a possible clinical application, because similar viruses have already been used for gene therapy in human patients.

But are the findings with mouse hearts applicable to humans? In order to answer this question, the scientists at the University of Bonn are working together with Prof. Natalia Trayanova’s Computational Cardiology Lab at the Institute for Computer Medicine and the Department of Biomedical Engineering at Johns Hopkins University (Baltimore, USA). There, optogenetic defibrillation is being tested in a computer model of the heart of a patient after cardiac infarction. ‘Our simulations show that a light pulse to the heart would also stop the cardiac arrhythmia of this patient’, reports Research Professor Patrick Boyle, who is also a lead author. To do so, however, the method from the University of Bonn had to be optimized for the human heart by using red light to stimulate the heart cells, instead of the blue light used in mice. This aspect of the study demonstrates the important role that can be played by computational modelling to guide and accelerate the systematic development of therapeutic applications for cardiac optogenetics, a technology that is still in its infancy.

University of Bonn www.uni-bonn.de/news/195-2016

In the operating room of the future, robots will be an integral part of the surgical team, working alongside human surgeons to make surgeries safer, faster and more precise. Engineers in Michael Yip’s lab at UC San Diego are developing advanced robotic systems to help make that vision a reality.

From intelligent algorithms that can enable robots to lend a helping hand during surgery, to ‘smart’ endoscopes that can autonomously maneuver through sensitive nooks and crannies inside the body, the robotics technologies in Yip’s lab are all inspired by a common goal: to augment the capabilities of surgeons.

The goal is not to replace human surgeons, but to better assist and enable them to do much more, said Yip, a professor of electrical engineering. Human surgeons, he explained, are still needed to make decisions that can’t be left to a robot, such as what treatment is best for the patient, or how a surgical procedure should be performed.

Meanwhile, robots will be used to perform tasks that humans cannot. For example, flexible and dexterous robots armed with high-power computing and sub-millimeter precision will be able to perform minimally invasive surgery, control complex instruments and navigate through spaces in the body that a human surgeon can’t access. These robots could perform other advanced tasks, such as creating real-time 3D maps inside the body as they self-navigate, relying on a patient’s medical data and imaging information.

This vision illustrates the idea of ‘Shared Autonomy,’ the theme of the most recent UC San Diego Contextual Robotics Institute Forum held on campus during October. In an age of increasing automation, researchers in the institute, such as Yip, are focused on developing robotic systems that can interact well in a human world and benefit society.

The da Vinci Surgical System is a robotic surgical system designed to perform minimally invasive surgery. The system, developed by the company Intuitive Surgical, is remotely controlled by a surgeon from a console. The system is equipped with four robotic arms, but a surgeon is able to control only two of them at a time. Yip’s ARCLab currently has a full da Vinci Surgical System dedicated for research in shared autonomy.

Yip’s team aims to put the other two arms to work. To do this, they are creating software and hardware that will enable these arms to function autonomously. A goal is to have these robotic arms assist the primary surgeon with routine surgical tasks (suction, irrigation or pulling tissue back) that are tedious and are currently performed by additional human surgeons.

‘This would reduce the number of surgeons in the operating room, which would reduce the overall cost of the surgery,’ said Nikhil Das, an electrical engineering Ph.D. student in Yip’s lab. It would also free up surgeons who normally do these tasks to see other patients, he added.

Das develops motion planning algorithms that will enable the auxiliary arms to move without hitting obstacles, such as the surgeon-controlled manipulator arms. He is working on this project with undergraduate student Naman Gupta, who is visiting from Birla Institute of Technology and Science in Pilani, India. Gupta implements these algorithms in a simulated da Vinci system’s robotic arm and is in the process of validating his approach before moving it onto the ARCLab’s da Vinci system.

Other students in the ARCLab are incorporating haptics into the system so that surgeons operating the robotic arms can recover the textures and sensations of feeling the tissues, a critical sensation missing in current systems.

‘We’re trying to close the gap between the surgeon and the robot,’ Das said.

To reach truly small scales, the ARCLab is developing its own robotic catheters. These catheters are meter-long, millimeter-diameter flexible robots that can access the deepest parts of the body from atraumatic locations such as the leg. With 8 wires that are individually controlled by 8 different motors, Yip’s lab can shape and steer the robot catheters in more complex configurations and navigate far more effectively than surgeons could do manually.

One goal is to automate the catheter and incorporate haptic controls so that the operator can receive feedback from the motors. ‘That’s what makes our catheter different from the steerable catheters in industry,’ said Aaron Gunn, a mechanical engineering undergraduate working on this project.

University of California San Diego ucsdnews.ucsd.edu/feature/engineers_developing_advanced_robotic_systems_that_will_become_surgeons

Many people who experience chest pain, but don’t have a heart attack, breathe a big sigh of relief when a stress test comes back negative for blockages in their blood vessels. But a new study by cardiac researchers at the Intermountain Medical Center Heart Institute in Salt Lake City found they may not be off the hook after all.

Researchers studied 658 men and women between the ages of 57 and 77 who passed a stress test for blocked arteries and who were later found to have calcium in their arteries after being screened by imaging technology that measured their total coronary artery calcification.

They found that five percent of patients who passed their stress test and later tested high for calcium in their arteries – 31 of 658 patients – went on to have an adverse cardiac event within one year. Such events included death, heart attack and stroke.

Researchers say there is something more doctors can do to assess a patient’s risk of future heart attack: check the calcium – a sign of plaque build-up – in a patient’s arteries.

‘We now have the ability to better measure coronary artery calcification,’ says Viet Le, MPAS, PA-C, lead author of the Intermountain Medical Center Heart Institute study.

‘People say, I’m good. They gave me a stress test,” said Le. ‘But it doesn’t tell the whole story. The story it tells is that on that day your engine – your heart – passed the test. Some of these people die within a year from a heart attack.’

Cardiac experts have known for years that calcium left by plaque is a good marker of heart disease, but there was not good imaging technology to measure it without exposing the patient to too much radiation, Le said. That changed about five years ago.

PET/CT, an advanced nuclear imaging technology that combines positron emission tomography (PET) and computed tomography (CT) in one machine, allows physicians doing a chemical stress test to also measure coronary artery calcification.

Calcification cannot be reversed, but the plaque that causes it can be reduced or stabilized with proper medication, diet and exercise.

Researchers found that 33 patients in the study, or five percent, had no or mild calcification, and they had no cardiac events. But there was a significant correlation between the amount of calcium and the occurrence of cardiac events in the remainder of the patients.

Twelve of 309 (3.88 percent) patients with moderate calcification had a cardiac event within a year, 10 of 190 (5.26 percent) with severe calcification had a cardiac event within a year, and nine of 126 (7.14 percent) with very severe calcification had a cardiac event within a year. In total, 16.28 percent of calcified patients in the study had a heart event.

The results confirmed for Le the value of assessing calcification in patients suspected of having clogged arteries.

‘Right now, it’s a neglected tool that should better be utilized,’ he said.

Intermountain Healthcare intermountainhealthcare.org/news/2016/11/cardiac-pet-ct-imaging-effective-calcium-blockage-assessing-heart-attack-risk/

Researchers from UT Southwestern’s Peter O’Donnell Jr. Brain Institute and Harold C. Simmons Comprehensive Cancer Center collaborated with investigators in the Advanced Imaging Research Center to identify 2HG (2-hydroxyglutarate), a metabolite that is produced in gliomas that carry IDH (isocitrate dehydrogenase) gene mutations.

Using MR spectroscopy, the team announced in 2012 that they could detect 2HG in the tumour with high sensitivity and specificity. This next-step study showed that 2HG can be useful in tracking the disease, researchers said.

‘This is the first non-invasive biomarker for brain cancer and represents a major advance for the field. Our current imaging is not nearly as precise and takes a longer time to see results,’ said senior author Dr. Maher, who holds the Theodore H. Strauss Professorship in Neuro-Oncology. ‘Within a week of starting treatment, we know whether we hit the target’. This new method will be a much more rapid way of assessing the therapy – allowing the physician to know to stop treatments that aren’t working or continue treatments that are.’

Most biomarkers are in the blood, so identifying biomarkers that can be tracked without drawing blood or obtaining a tissue biopsy is particularly valuable, said Dr. A. Dean Sherry, Director of the Advanced Imaging Research Center and Professor of Radiology at UT Southwestern, and Professor of Chemistry at UT Dallas, where he holds the Cecil H. and Ida Green Distinguished Chair in Systems Biology.

The technique also may serve as a model to develop other imaging biomarkers for the brain, and already is being used to learn more about the biology of glioma, the most common type of brain cancer.

‘In terms of research, the biomarker is a window’ into IDH-mutant glioma biology and we are using it to learn more about how the tumour grows, responds to therapy, and ultimately becomes resistant to treatment,’ said lead author Dr. Changho Choi, Professor of Radiology and with the Advanced Imaging Research Center, where the study was performed using a dedicated research MR scanner.

2HG tracking also could prove useful in diagnosing some brain tumours in which typical surgical procedures to obtain tissue samples can’t be done. That may be because the tumour isn’t accessible, such as near the brainstem, or when trying to get a sample could cause neurological damage. These patients are excluded from clinical trials because of the lack of available tumour tissue for diagnostic analyses.

‘We established in this study that 2HG levels in these tumours can be used to make a presumptive’ molecular diagnosis of an IDH mutation, based solely on imaging,’ said Dr. Choi.

UT Southwestern Medical Center www.utsouthwestern.edu/newsroom/news-releases/year-2016/oct/biomarker-tracks-tumour.html

Researchers investigating a novel device to repair the mitral heart valve report 100 percent procedural success in a safety and performance study, the first such study done in humans. The image-guided device, based on technology developed at the University of Maryland School of Medicine, is deployed through a tiny opening in a beating heart, avoids open-heart surgery, automates a key part of the valve repair process, simplifies the procedure and reduces operating room time.
Traditional mitral valve repair is performed during open heart surgery, a lengthy operation in which the patient’s chest is opened, the heart is stopped and circulation is maintained with a heart-lung bypass machine. Recovery can take months, and patients face significant risks. As a result, there is considerable interest in finding less invasive mitral valve treatment options.
‘We think this is a safer approach than open heart surgery,’ says principal investigator James S. Gammie, MD, professor and chief of cardiac surgery at the University of Maryland School of Medicine. ‘We think the safety profile is going to be better and, ultimately, people will be able to go home from the hospital the next day.’
The device, known as the Harpoon TSD-5, made by Harpoon Medical Inc. of Baltimore, is an investigational device. At the present time, the US Food and Drug Administration has not approved the device for use in patients in the United States. It is designed to treat degenerative mitral regurgitation (MR), the most common type of heart valve disorder. In MR, a leaky valve lets blood travel in the wrong direction on the left side of the heart, causing shortness of breath, fluid retention, irregular heartbeats and fatigue. MR develops when the small fibrous cords that open and close the valve’s flaps, known as leaflets, are broken or stretched, preventing them from closing tightly and causing the leaflets to bulge or prolapse upward toward the left atrium. The natural cords connect the valve flaps to muscles inside the heart that contract to close the mitral valve, which gets its name because its two flaps resemble a bishop’s mitre.
The TSD-5 anchors artificial cords on the flaps to take the place of the natural cords. The artificial cords are made of expanded polytetrafluoroethylene (ePTFE), a polymer commonly used as sutures in cardiac surgery.
Surgeons insert the device into the beating heart through a tiny opening in the ribcage and, using echocardiographic imaging, guide it to the surface of the defective mitral flaps. When the surgeon determines the optimal placement for an artificial cord, the device is actuated and a specially designed needle wrapped with 50 coils of ePTFE makes a tiny hole and sends the cord material through the flap. An automated process makes a knot to hold the cord in place. The other end of the cord is adjusted for optimum length and tied to the outside layer of the heart, the epicardium. Three or four cords are required for most cases.
Gammie says the ability to make adjustments to the artificial cords while the heart is beating is a key advantage over open heart surgery: ‘The heart’s fully loaded and beating and we can just adjust the length of the cords to optimize the result, and only when we’re really happy do we tie it off.’

University of Maryland School of Medicine http://tinyurl.com/j5m9lmp