Tag Archive for: Yue-Hin Loke

imaging of blood flow in the heart

4D flow explained: Advanced imaging measures critical blood flow characteristics of single ventricle hearts

Yue-Hin “Tom” Loke, M.D., pediatric cardiologist and director of the 3D Cardiac Visualization Laboratory at Children’s National Hospital, uses magnetic resonance imaging and software rendering to create novel 4D flow images of children with single ventricle congenital heart disease.

“My research measures the degree of vortex formation (and) the degree of energy loss in the atrium as potential measurements of heart health and uses these measurements as a potential gauge of the heart health of children born with single ventricle conditions including hypoplastic left heart syndrome,” he says. “This information can be used to guide the management of the care for children with congenital heart disease. This technology provides valuable insight into how well the heart is working, especially before the Fontan procedure.”

Learn more about the approach and how it impacts clinical care decisions in the Children’s National Heart Institute.

animation showing MRI cardiac imaging

Advanced MRI hopes to improve outcomes for Fontan cardiac patients

animation showing MRI cardiac imaging

Chief of Cardiac Surgery Yves d’Udekem, M.D., calls this “fourth-dimensional imaging” that identifies if blood flows swiftly, smoothly, or is subjected to swirls or turbulences that impede the effectiveness of the flow.

Cardiac imaging specialists and cardiac surgeons at Children’s National Hospital are applying advanced magnetic resonance imaging visualization techniques to understand the intricacies of blood flow within the heart chambers of children with single ventricle heart defects like hypoplastic left heart syndrome (HLHS).

The data allows surgeons to make critical corrections to the atrioventricular valve — the valve between the atrium and ventricle of the heart — before a child undergoes the single ventricle procedure known as the Fontan.

Yves d’Udekem, M.D., chief of Cardiac Surgery at Children’s National, says that eliminating leakage of the atrioventricular valve before a child undergoes the Fontan may improve a child’s quality of life after Fontan and reduce the likelihood of heart failure, transplant or death long term.

The big picture

Patients with only one functioning pumping chamber, or ventricle, have been on the same treatment trajectory for decades. However, critical international efforts to collect and analyze long-term outcomes for patients with Fontan circulations have led surgeons like d’Udekem to rethink what quality of life and a positive outcome means for these patients. This includes patients in the Australia and New Zealand Fontan Registry founded by d’Udekem while at Royal Children’s Hospital in Australia.

Research based on data in the patient registries shows that atrioventricular valve leakage plays a critical role in the outcomes for patients with single ventricle defects. For children with Fontan circulation, significant leakage of this valve leads to worse outcomes.

Moving the field forward

Treatment decisions for children with single ventricle heart defects are often made based on commonly used heart imaging to determine the effect of valve leakage based on two limited, key variables: the size and the squeeze of the heart. However, this is a late effect and may not reflect the true impact on children with single ventricle hearts.

The team at Children’s National — including d’Udekem and Yue-Hin Loke, M.D., cardiac MRI specialist and director of the 3D Cardiac Visualization Laboratory — use cardiac MRI to measure the flow between heart chambers. Special software can measure abnormal flow and energy losses inside the heart, drawing on principles of physics and engineering.

“Dr. Loke not only gathers three-dimensional imaging of the heart through every heartbeat, he also gathers brand new types of colored imaging of blood flow itself, showing how effectively it is propelled by the heart,” says d’Udekem. “This ‘fourth-dimensional imaging’ identifies whether the blood flows swiftly, smoothly or whether it is subjected to swirls or turbulences that impede the effectiveness of the flow.”

Children’s National leads the way

Harnessing the visualization technology and analysis for clinical care of patients with single ventricle defects is relatively new in the United States, but it has become a vital part of the routine, clinical pre-Fontan evaluations at Children’s National.

Few locations in the United States have the mechanisms and expertise to study abnormal flow patterns in children with single ventricle defects. Children’s National collaborates with engineers to help parse the information into clear-cut takeaways for the clinical teams to use in their treatment planning.

Also, while other centers have access to this technology, not many centers have cardiac surgeons like d’Udekem who have an active interest in applying the key learnings from this data as quickly as possible to improve outcomes for patients.

Loke describes the collaboration at Children’s National as a “unique crossroads of clinical need and clinical interest to help these kids in very bold ways.”

What’s next

d’Udekem and Loke are engaged in a comprehensive project that analyzes the impact of atrioventricular valve leakage to ensure that the flow inside the heart is optimized before a Fontan procedure.

The research will map the efficiency of blood flow between the atrium and ventricle before surgery and after a surgical correction is made. The goal is to test the hypothesis that better atrioventricular circulation before Fontan can make a big difference for patients’ long-term quality of life and overall health.

mother measuring sick child's temperature

Connections between Kawasaki disease and MIS-C

mother measuring sick child's temperature

A new review article enumerates some key similarities and differences between MIS-C and Kawasaki disease.

Since May 2020, there has been some attention in the general public and the news media to a specific constellation of symptoms seen in children with COVID-19 or who have been exposed to COVID-19. For a time, headlines even called it a “Kawasaki-like” disease. At first glance, both the symptoms and the effective treatments are remarkably similar. However, a new review published in Trends in Cardiovascular Medicine finds that under closer scrutiny, the two conditions have some interesting differences as well.

“At the beginning of this journey, we thought we might be missing actual cases of Kawasaki disease because we identified a few patients who presented late and developed coronary artery abnormalities,” says Ashraf Harahsheh, M.D., senior author of the review article, “Multisystem inflammatory syndrome in children: Is there a linkage to Kawasaki disease?” and a cardiologist at Children’s National Hospital. “But as time passed, children exposed to COVID-19 started to present with a particular constellation of symptoms that actually had some important similarities and distinctions from Kawasaki.”

Similarities between Kawasaki disease and MIS-C

Both disease patterns seem to have a common trigger that provokes the inflammatory cascade reaction in genetically susceptible children, the authors write. However, there is also early evidence that children with each disease have different genetic markers, meaning different populations are genetically susceptible to each disease.

Additionally, the authors found that the massive activation of pro-inflammatory cytokines seen in MIS-C, also known as a “cytokine storm,” overlaps with a similar occurrence seen in Kawasaki disease, adult COVID-19 patients, toxic shock syndrome and some other viral infections.

Primary differences between Kawasaki disease and MIS-C

Overall, when compared to Kawasaki disease, children with MIS-C tend to:

  • Present at an older age
  • Have a more profound form of inflammation
  • Have more gastrointestinal manifestation
  • Show different laboratory findings
  • Have greater risk of left ventricle dysfunction and shock

Further study of both Kawasaki and MIS-C needed

Despite noted differences, the authors are also careful to credit the documented similarities between Kawasaki disease and MIS-C as a key to the quick identification of the new syndrome in children. The study of Kawasaki disease also gave clinicians a valid basis to begin developing diagnostic recommendations and treatment protocols.

The review’s first author Yue-Hin Loke, M.D., who is also a cardiologist at Children’s National, says, “The quick recognition of MIS-C is only possible because of meticulous research conducted by Dr. Tomisaku Kawasaki, who recently passed away on June 5th, 2020. Even though some aspects of both are still shrouded in mystery, the previous research and clinical advancements made in Kawasaki disease set the stage for our immediate response to MIS-C.”

“Previous research provided key information for cardiologists facing this new syndrome, including the necessity of routine echocardiograms to watch for coronary artery abnormalities (CAAs) and for use of  intravenous immunoglobulin (IVIG) to mitigate  the development of CAAs,” says Charles Berul, M.D., chief of Cardiology at Children’s National and a co-author. “Both of these factors have played a key role in reducing the mortality of MIS-C to almost zero.”

The authors note that more research is needed to understand both Kawasaki disease and the specifics of MIS-C, but that what is learned about the mechanisms of one can and should inform study and treatment of the other. And in the meantime, caution and continued surveillance of these patients, especially with respect to coronary artery and myocardial function, will continue to improve the long-term outcomes for both syndromes.