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newborn baby

Directly measuring function in tiny hearts

newborn baby

The amount of blood the heart pumps in one minute can be directly measured safely in newborns by monitoring changes in blood velocity after injecting saline, indicates the first clinical study of direct cardiac output measurement in newborns.

The amount of blood that the heart pumps in one minute (cardiac output) can be directly measured safely in newborns by monitoring changes in blood velocity after injecting saline, indicates a paper published online Dec. 17, 2019 in the Journal of Pediatrics and Neonatal Medicine. The research, conducted by Children’s National Hospital faculty, is believed to be the first clinical study of direct cardiac output measurement in newborns.

Right now, cardiac output is measured indirectly in the nation’s neonatal intensive care units (NICU) using newborns’ blood pressure, heart rate, urine output and other indirect measures. However, these techniques can produce imprecise readings in children. And the field lacks a feasible “gold standard” to measure cardiac output in newborns.

The COstatus monitor already uses ultrasound dilution – the expected decrease in the velocity of blood when saline is injected, producing a dilution curve. A Children’s National research team used ultrasound dilution in their small pilot study to gauge the feasibility of directly measuring cardiac output in newborns.

“Infants who stand to benefit most from directly monitoring cardiac hemodynamics are often so sick they already have central venous access,” says Khodayar Rais-Bahrami, M.D., an attending neonatologist at Children’s National and the study’s senior author. “Using the COstatus monitor in these children would enable the clinical team to personalize care based on the newborn’s current hemodynamic status, while introducing minimal fluid during measurements,” Dr. Rais-Bahrami adds.

COstatus monitor

The COstatus Monitor uses an extracorporeal loop attached to arterial and venous lines to measure cardiac output using ultrasound dilution. The research team injected 1mL/kg of body temperature saline into the loop and performed up to two measurement sessions daily.

The research team recruited 12 newborns younger than 2 weeks old who already had central venous and arterial access. The venous line of the arteriovenous AV loop is connected to the umbilical venous catheter while the COstatus monitor’s arterial line is connected to the umbilical arterial catheter. During measurement sessions, two injections of solution are injected into the venous loop, allowing for two measures of cardiac output, cardiac index, active circulating volume index, central blood volume index and systemic vascular resistance index.

Infants enrolled in the pilot study underwent up to two measurement sessions per day for up to four days, for a total of 54 cardiac hemodynamic measurements. The newborns ranged from 720 to 3,740 grams in weight and 24 to 41.3 weeks in gestational age.

The infants’ mean cardiac output was 0.43L/min and increased with gestational age. By contrast, the mean cardiac index was 197mL/kg/min and changed little with infants’ increasing maturity – either by gestational age or postnatal age. Two of the study participants were undergoing therapeutic cooling for hypoxic-ischemic encephalopathy and had their measurements taken during cooling and after rewarming.

“Although this study size is small, it demonstrates that this minimally invasive technique can safely be used in newborns to directly measure cardiac hemodynamics,” says Simranjeet S. Sran, M.D., a Children’s National neonatalogist and the study’s lead author. “This technology may allow for more precise and personalized care of critically ill newborns in a range of disease states – real-world utility in NICUs that serve some of the youngest and sickest newborns,” Dr. Sran adds.

The research team notes that direct measurement by ultrasound dilution revealed a stark increase in cardiac index as infants undergoing therapeutic hypothermia were rewarmed, raising questions about whether indirect measures using other technology, such as echocardiography, underestimate hypothermia’s effect on hemodynamics.

In addition to Drs. Rais-Bahrami and Sran, Mariam Said, M.D., also a Children’s National neonatalogist, was a study co-author.

Suvankar Majumdar

Spotlight on Suvankar Majumdar, M.D.

Suvankar Majumdar

As a provider with international experience, Suvankar Majumdar, M.D., joined Children’s National in August 2017 as chief of Children’s Division of Hematology within the Center for Cancer and Blood Disorders. Dr. Majumdar is excited to be at Children’s National because of the opportunities for growth, cutting-edge research and continuing education that our diverse population of patients can provide clinicians.

Born in Zambia, in southern Africa, and educated in the United Kingdom, Dr. Majumdar moved to Zimbabwe to study medicine, which he considers the turning point of his career. While in medical school, Dr. Majumdar oversaw and managed the treatment of patients with HIV and other chronic illnesses and determined that blood disorders, particularly sickle cell, was where he wanted to place his focus. Since then, he has served as the Director of the Comprehensive Pediatric Sickle Cell Program as well as Director of the Hemophilia Treatment Center at the University of Mississippi and is a recognized leader in hematology and sickle cell disease. It is this expertise, as well as his dedication to research studies, that have already made him an asset to Children’s National.

Within the Division of Hematology, Children’s providers focus on treating patients with blood disorders, bleeding and clotting disorders, red blood cell disorders (such as sickle cell) and more. Since coming to Children’s National, Dr. Majumdar has experienced a tremendous amount of dedication and enthusiasm from his colleagues. “I’m excited to build on what our faculty has accomplished so far. We’re already well poised to become a national leader in hematology,” he says. “I have no doubt that we will continue to accomplish our goals through collaboration and working toward a common life-saving cause.”

One of his immediate goals for the division is to focus on bringing improved patient care and accessibility in the surrounding Washington area. Additionally, Dr. Majumdar is currently conducting two research studies for sickle cell disease. As one of his studies enters the second phase, he’s focused on seeing the impact of an intravenous citrulline, a nitric oxide booster, on patients with sickle cell disease. Another study has begun to determine if specific genetic mutations that cause prolonged QT, or irregular heartbeats in patients, cause mortality, as sickle cell patients are predisposed to cardiac episodes.

It is Dr. Majumdar’s hope that the hematology team at Children’s National will also continue training the next generation of providers to advance research, education and clinical aspects of the field. To those looking to join the specialty, Dr. Majumdar suggests keeping an open mind when it comes to collaborating with colleagues. “My dad always said to my siblings and I that ‘to break one stick is easy, but to break three sticks is harder’ and really impressed upon us that we’re stronger together,” he says. “By working together, we’re more likely to produce the results that we’re looking for.”

Being located in the nation’s capital, providers at Children’s National are accustomed to seeing a diverse array of patients. For Dr. Majumdar, this presents a unique opportunity. “Meeting and interacting with different patients and families was really appealing when I decided to come to Children’s National. The variety of cases we see in the Division of Hematology can definitely present new challenges, but it’s also more rewarding,” he says.

Working with the pediatric population is also a passion of his. “Children are resilient and tend to bounce back quickly,” Dr. Majumdar says. “As a parent, I try to empathize with treatment concerns and always treat every child as if they were my own. I’m always going to make sure it’s the best level of care possible.”

3d illustration of a constricted and narrowed artery

dnDSA and African American ethnicity linked with thickening of blood vessels after kidney transplant

3d illustration of a constricted and narrowed artery

Emerging evidence links dnDSA with increased risk of accelerated systemic hardening of the arteries (arteriosclerosis) and major cardiac events in adult organ transplant recipients. However, this phenomenon has not been studied extensively in children who receive kidney transplants.

Children who developed anti-human leukocyte antibodies against their donor kidney, known as de novo donor-specific antibodies (dnDSA), after kidney transplant were more likely to experience carotid intima-media thickening (CIMT) than those without these antibodies, according to preliminary research presented May 7, 2019, during the 10th Congress of the International Pediatric Transplant Association.

dnDSA play a key role in the survival of a transplanted organ. While human leukocyte antibodies protect the body from infection, dnDSA are a major cause of allograft loss. CIMT measures the thickness of the intima and media layers of the carotid artery and can serve as an early marker of cardiac disease.

Emerging evidence links dnDSA with increased risk of accelerated systemic hardening of the arteries (arteriosclerosis) and major cardiac events in adult organ transplant recipients. However, this phenomenon has not been studied extensively in children who receive kidney transplants.

To investigate the issue, Children’s researchers enrolled 38 children who had received kidney transplants and matched them by race with 20 healthy children. They measured their CIMT, blood pressure and lipids 18 months and 30 months after their kidney transplants. They monitored dnDSA at 18 months and 30 months after kidney transplant. The transplant recipients’ median age was 11.3 years, 50 percent were African American, and 21% developed dnDSA.

“In this prospective controlled cohort study, we compared outcomes among patients who developed dnDSA with transplant recipients who did not develop dnDSA and with race-matched healthy kids,” says Kristen Sgambat, Ph.D., a pediatric renal dietitian at Children’s National who was the study’s lead author.  “Children with dnDSA after transplant had 5.5% thicker CIMT than those who did not have dnDSA. Being African American was also independently associated with a 9.2% increase in CIMT among transplant recipients.”

Additional studies will need to be conducted in larger numbers of pediatric kidney transplant recipients to verify this preliminary association, Sgambat adds.

10th Congress of the International Pediatric Transplant Association presentation:

  • “Circulating de novo donor-specific antibodies and carotid intima-media thickness in pediatric kidney transplant recipients.”

Kristen Sgambat, Ph.D., pediatric renal dietitian and study lead author; Sarah Clauss, M.D., cardiologist and study co-author; and Asha Moudgil, M.D., Medical Director, Transplant and senior study author, all of Children’s National.