Plastic bronchitis is a rare but serious diagnosis for congenital heart disease patients. The condition, which is usually a complication after Fontan surgery, occurs when lymph fluid builds up and leaks into the lungs, hardening into rubbery casts that can cause difficulty breathing. Only a small handful of U.S. hospitals regularly treat plastic bronchitis, which usually involves accessing the lymphatic system (thoracic duct and its tributaries) transabdominally. Interventional cardiologists and radiologists at Children’s Health℠, have developed a less invasive approach – the transvenous retrograde cannulation of the thoracic duct – that significantly minimizes complications and speeds recovery time.
The innovative approach combines advanced MRI imaging with catheterization of the thoracic duct through a novel entry point. Suren Reddy, M.D., Director of Pediatric Interventional Cardiology at Children’s Health and Professor at UT Southwestern, has performed the intervention on more than 30 patients. Two case studies illustrate how it can save lives, reduce risks and help some children become better heart transplant candidates.
Starting a Lymphatic Evaluation and Interventional Program (LEIP)
Children’s Health is the only center in the world using a hybrid Cardiac Cath-MRI suite to perform complex diagnostic cardiac catheterization procedures to treat complex congenital heart disease. Complex procedures include a detailed pre-Fontan right and left heart catheterization. The team also performed the first-in-human transcatheter pulmonary valvuloplasty procedure that was transmitted live to the Society for Cardiovascular Magnetic Resonance conference in 2020.
While the strong collaboration between the cardiac catheterization and cardiac MRI teams made starting the LEIP relatively straightforward, there were initial hurdles. For example, diagnostic MR lymphangiography procedures were previously not performed at Children’s Health. To learn this procedure, Dr. Reddy turned to colleagues at Children’s Hospital of Philadelphia (CHOP).
This started when Dr. Reddy accompanied one of his own patients to CHOP for the lymphatic intervention. After studying the procedure as it was performed by his CHOP colleagues and seeing its potential to help patients in North Texas, Dr. Reddy decided to bring it to the Heart Center at Children’s Health and enlisted the aid of Tarique Hussain, M.D., Director for Cardiac Magnetic Resonance Imaging at Children’s Health and Professor at UT Southwestern. After successfully performing several lymphatic intervention procedures, the team grew stronger with the addition of Sheena Pimpalwar, M.D., Director of Pediatric Interventional Radiology at Children’s Health and Associate Professor at UT Southwestern.
A new access point for lymphatic intervention: “The road less travelled”
Lymphatic procedures start with placing tiny needles in the lymph nodes/channels in the groin and abdomen. This enables evaluation of the lymphatic anatomy and flow with advanced MR imaging to determine where lymphatic fluid is flowing and leaking. The damaged areas can then be accessed during catheterization and sealed to eliminate further leaks and restore pulmonary function.
Traditionally, interventionalists use a long needle that is advanced directly from the skin into abdominal cavity through the organs to gain access into the thoracic duct (the largest lymphatic channel in the body). But this approach comes with significant risks, including abdominal pain, bleeding, infection, systemic inflammatory response, sepsis and trauma to important organs and vessels in the abdomen.
As an alternative, Dr. Reddy explored accessing the thoracic duct by entering through the neck in a technique called, the retrograde transvenous approach. Instead of directly piercing the abdomen, he uses the traditional transcatheter route from the groin blood vessels to enter the thoracic duct entrance in the left neck area. Previously, this retrograde approach was used in a limited number of adult patients but generally not used in pediatric patients.
However, Drs. Reddy and Pimpalwar found a champagne-flute-shaped lymphatic valve at the entrance of the thoracic duct connection to the left neck vein that provides safe passage for lymphatic interventions while reducing infection and other major risks associated with transabdominal injection. Over the past 3 – 4 years, Drs. Reddy and Pimpalwar have fine-tuned this technique and shared their expertise at multiple national and international conferences. Dr. Reddy routinely gives talks and fields phone calls from various institutions seeking his guidance to help access the lymphatic channels via the less risky transvenous retrograde approach.
“If you have a complex patient who is already suffering and you go through the abdomen, you put them at higher risk for multiple complications, and the patients take many steps backwards before getting better,” Reddy says. “If you fail at the reverse or retrograde transvenous approach, we can still do the high-risk prograde transabdominal approach.”
The benefits of retrograde transvenous access
After lymphatic imaging, the patient is transferred to the cardiac catheterization laboratory where Dr. Reddy and his team access the lymphatic system using the retrograde transvenous access then proceed with lymphatic interventions. Some patients need the lymphatic channels to be occluded. In others, the thoracic duct needs to be dilated with balloons and/or stents. Post- lymphatic intervention, patients are discharged within a few days (versus weeks of recovery following transabdominal access). Then they’re monitored closely for recurrence of lymphatic symptoms.
Most important, lymphatic intervention can enable patients to use their own hearts for a longer period, potentially delaying or avoiding heart transplant. In many instances, the lymphatic complications in Fontan patients make them nutritionally depleted and put them at very high risk for significant morbidity and mortality after heart transplant. In extreme cases, patients are denied heart transplant listing.
Dr. Reddy and his team has performed successful lymphatic interventions in patients who then either became good candidates for heart transplant or no longer needed transplant after the procedure. One of Dr. Reddy’s patients – who was referred for heart transplant – has retained his heart for more than five years after a successful lymphatic intervention.
“As long as we can address these lymphatic issues in Fontan patients, we can either delay or avoid heart transplants,” Dr. Reddy says, “which is important because there are far more Fontan patients than available hearts.”
Case study: Avoiding the transplant list
A teenage male developed plastic bronchitis after a Fontan surgery at another institution. The condition left him blue and gasping for breath, and lymphatic intervention was his best chance for survival.
After the patient was transferred to Children’s Health, Dr. Reddy and his team found that:
- The patient’s high BMI precluded him from the transplant list
- His failing Fontan physiology made him more susceptible to plastic bronchitis and other pulmonary issues
Dr. Reddy performed lymphatic intervention via retrograde access. The patient has had no further lymphatic issues. Since he is able to breathe well and his lungs are free of lymphatic casts, he is able to do many physical activities and follows a structured diet and exercise regimen that helped him reduce his BMI to a range where he can now be re-evaluated for transplant. But thanks to his successful lymphatic intervention, he is able to lead a physically active lifestyle and can function well using his own heart. He does not need a heart transplant at this time.
Case study: Performing lymphatic intervention without MRI
A teenage male with heart disease developed myocarditis following Fontan surgery. He subsequently was implanted with a VAD, then later developed plastic bronchitis, coughing up solid lymphatic casts that restricted his breathing and reduced his chances of a successful transplant. He was temporarily removed from the transplant list to await clearance of plastic bronchitis.
Dr. Reddy was asked to pursue lymphatic intervention but faced a significant challenge: He couldn’t use MRI to delineate the lymphatic anatomy and flow due to the metallic interference from the VAD. Dr. Reddy moved ahead with the procedure, using his existing knowledge of the location of the thoracic duct entrance to access it via the transcatheter retrograde approach, clear the lymphatic blockages and occlude the culprit abnormal channels.
After the surgery, the patient was extubated within 24-hours and started clearing lymphatic casts a few days later. He was subsequently placed back on the transplant list and received a new heart with no lung complications.