For decades, cardiac researcher James McCully, PhD, has been spellbound by the idea of using mitochondria, the “batteries” of the body’s cells, as a therapy to boost heart function. Finally, a clinical trial at Boston Children’s Hospital is bringing his vision — a therapy called mitochondrial transplantation — to life.
Mitochondria, small structures inside all of our cells, synthesize the essential energy that our cells need to function. In the field of cardiac surgery, a well-known condition called ischemia often damages mitochondria and its mitochondrial DNA inside the heart’s muscle cells, causing the heart to weaken and pump blood less efficiently. Ischemia, a condition of reduced or restricted blood flow, can be caused by congenital heart defects, coronary artery disease and cardiac arrest.
For the smallest and most vulnerable patients who are born with severe heart defects, a heart-lung bypass machine called extracorporeal membrane oxygenation (ECMO) can help restore blood flow and oxygenation to the heart. But even after blood flow has returned, the mitochondria and their DNA remain damaged.
“In the very young and the very old, especially, their hearts are not able to bounce back,” says McCully.
Ischemia can be fatal for the tiniest patients
After cardiac arrest, for instance, a child’s mortality rate jumps to above 40 percent because of ischemia’s effects on mitochondria. If a child’s heart is too weak to function without the support of ECMO, his or her risk of dying increases each additional day spent connected to the machine.
But what if healthy mitochondria could come to the rescue and replace the damaged ones? …
Pulmonary vein stenosis (PVS) is a rare disease in which abnormal cells build up inside the veins responsible for carrying oxygen-rich blood from the lungs to the heart. It restricts blood flow through these vessels, eventually sealing them off entirely if left untreated. Typically affecting young children, the most severe form of PVS progresses very quickly and can cause death within a matter of months after diagnosis.
Until recently, treatment options have been limited to keeping the pulmonary veins open through catheterization or surgery. Yet this approach only removes the cells but does nothing to prevent their regrowth. Now, a clinical trial shows that adding chemotherapy to a treatment regimen including catheterization and surgery can deter abnormal cellular growth and finally give children with PVS a chance to grow up.
“Through this approach, we’ve created the first-ever population of survivors who are living with severe PVS,” saysChristina Ireland, RN, MS, FNP, who has managed enrolling patients in the trial and treating new patients since the trial ended. “We’ve changed this disease from an acute killer to a chronic, manageable condition.” …
Children can be at risk for compromised breathing after surgery or from conditions like asthma, congestive heart failure or sleep apnea. Opioid therapy and sedation for medical procedures can also depress breathing. Unless a child is sick enough to have a breathing tube, respiratory problems can be difficult to detect early. Yet early detection can mean the difference between life and death.
“There is currently no real-time objective measure,” says Viviane Nasr, MD, an anesthesiologist with Boston Children’s Hospital’s Division of Cardiac Anesthesia. “Instead, respiratory assessment relies on oximetry data, a late indicator of respiratory decline, and on subjective clinical assessment.”
A new device, recently cleared by the FDA for children 1 year and older in medical settings, provides an easy, noninvasive way to tell how much air the lungs are receiving in real time. It can signal problems as much as 15-30 minutes before standard pulse oximetry picks up low blood oxygenation, according to one study. …
Everything from food aspiration to an asthma attack to heart failure can cause a patient to die from asphyxia, or lack of oxygen. For more than a decade, the Translational Research Laboratory (TRL) of Boston Children’s Hospital’s Heart Center has been pursuing a dream: tiny, oxygen-filled bubbles that can be safely injected directly into the blood, resuscitating patients who can’t breathe.
The lab’s first generation of bubbles were made with a fatty acid, but the lipid shells weren’t stable enough for long-term storage or clinical use. The bubbles popped open too easily. …
Soft robotic actuators, which are pneumatic artificial muscles designed and programmed to perform lifelike motions, have recently emerged as an attractive alternative to more rigid components that have conventionally been used in biomedical devices. In fact, earlier this year, a Boston Children’s Hospital team revealed a proof-of-concept soft robotic sleeve that could support the function of a failing heart.
Despite this promising innovation, the team recognized that many pediatric heart patients have more one-sided congenital heart conditions. These patients are not experiencing failure of the entire heart — instead, congenital conditions have caused disease in either the heart’s right or left ventricle, but not both.
“We set out to develop new technology that would help one diseased ventricle, when the patient is in isolated left or right heart failure, pull blood into the chamber and then effectively pump it into the circulatory system,” says Nikolay Vasilyev, MD, a researcher in cardiac surgery at Boston Children’s.
Now, Vasilyev and his collaborators — researchers from Boston Children’s, the Harvard John A. Paulson School of Engineering and Applied Sciences and the Wyss Institute for Biologically Inspired Engineering at Harvard University — have revealed their soft robotic solution. They describe their system in a paper published online in Science Robotics today. …
Placed near the heart, the device can potentially predict life-threatening cardiac arrest in critically ill heart patients, according to tests in animal models. The technology was developed through a collaboration between Boston Children’s Hospital and device maker Pendar Technologies (Cambridge, Mass.).
“With current technologies, we cannot predict when a patient’s heart will stop,” says John Kheir, MD, of Boston Children’s Heart Center, who co-led the study. “We can examine heart function on the echocardiogram and measure blood pressure, but until the last second, the heart can compensate quite well for low oxygen conditions. Once cardiac arrest occurs, its consequences can be life-long, even when patients recover.”
In critically ill patients with compromised circulation or breathing, oxygen delivery is often impaired. The new device measures, in real time, whether enough oxygen is reaching the mitochondria, the organelles that provide cells with energy. …
About 1 out of 100 babies are born with a congenital heart defects. Thanks to medical and surgical advances, these children usually survive into adulthood, but they are often left with developmental, behavioral or learning challenges.
Children with “single-ventricle” defects — in which one of the heart’s two pumping chambers is too small or weak to function properly — are especially at risk for neurodevelopmental problems. “Single-ventricle physiology creates cerebrovascular hemodynamics that can reduce oxygen delivery to the brain,” explains Jane Newburger, MD, MPH, director of the Cardiac Neurodevelopmental Program at Boston Children’s Hospital.
How does this play out in adolescence? In three recent studies, Boston Children’s Heart Center collaborated with the departments of Neurology and Psychiatry to track neurodevelopmental outcomes after corrective Fontan operations. They evaluated preteens and teens as old as 19 — the longest follow-up to date. …
Children in severe heart failure sometimes have a ventricular assist device (VAD) implanted in their chest. VADs are electrically-powered heart pumps that can tide children over while they wait for a heart transplant. They can also be implanted long term if a child is ineligible for transplant, or simply buy children time to recover their own heart function.
Because problems with VADs can be life-threatening, families need extensive training in managing the device and its external controller at home. Nurse practitioner Beth Hawkins RN, MSN, FNP-C, and her colleagues in the Boston Children’s VAD Program begin the training at the child’s hospital bedside while they are still in the cardiac ICU. But despite lectures, demos and practice opportunities, the prospect of maintaining a VAD remains terrifying for many parents and children.
“A lot of families feel their child is attached to a ticking time bomb that could go off at any time,” says Hawkins. “Many say taking a child home on a VAD feels like having a newborn baby again.”
Hawkins realized that families needed more support. …
Every year, about 2,100 people receive heart transplants in the U.S., while 5.7 million suffer from heart failure. Given the scarcity of available donor hearts, clinicians and biomedical engineers from Boston Children’s Hospital and Harvard University have spent several years developing a mechanical alternative.
Heart failure occurs when one or both of the heart’s ventricles can no longer collect or pump blood effectively. Ventricular assist devices (VADs) are already used to sustain end-stage heart failure patients awaiting transplant, replacing the work of the ventricles through tubes that take blood out of the heart, send it through pumps or rotors and power it back into a patient’s bloodstream. But while VADs extend lives, they can cause complications. …
The heart is a dynamic, beating organ, and until now it has been challenging to fully capture its complexity by magnetic resonance imaging (MRI). In an ideal world, doctors could create a 3-D visual representation of each patient’s unique heart and watch as it pumps, moving through each phase of the cardiac cycle. Andrew Powell, MD, Chief of the Division of Cardiac Imaging at Boston Children’s Hospital, and his physicist colleague Mehdi Hedjazi Moghari, PhD, have taken steps toward realizing this vision.
The standard cardiac MRI includes multiple 2-D image slices stacked next to each other that must be carefully positioned by the MRI technologist based on a patient’s anatomy. Planning the location and angle for the slices requires a highly-knowledgeable operator and takes time.
Powell and Moghari are working on a new MRI-based technology that can produce moving 3-D images of the heart. It allows cardiologists and cardiac surgeons to see a patient’s heart from any angle and observe its movement throughout the entire cardiac cycle. …