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Johnson, Jonathan N.

https://orcid.org/0000-0001-7850-0636

Mayo Clinic

Mayo Clinic

Citations 85

Pediatric heart transplantation
Johnson, Jonathan N., Kindel, Steven J. , Ameduri, Rebecca , Johnson, Jonathan N.

Current Opinion in Organ Transplantation | April 4, 2026 | Volume: 31 | Issue: 3 | Pages: 167-171

10.1097/mot.0000000000001289 Get It

Purpose of review To summarize important papers published in the pediatric heart transplantation in the last year. Recent findings While advances have been made for pediatric patients who need heart transplantation, considerable challenges remain. Donor availability remains a key challenge, and work to both increase the number of donors and the quality of donor organs is ongoing. The field of pediatric heart transplantation benefits from registries such as the Pediatric Heart Transplant Society (PHTS) and learning networks such as the Advanced Cardiac Therapies Improving Outcomes Network (ACTION), allowing for multisite collaboration to optimize survival both before and after transplant, and to share learning about complex cases. Psychosocial evaluations of potential recipients and families can be challenging, and a consensus framework is now available for these evaluations, to provide appropriate oversight and management of a scarce resource. Looking ahead, heart transplant specialists are anticipating advances in xenotransplantation, which has the potential to revolutionize current standards of care. Summary Donor availability and organ scarcity are the dominant challenges we face, with many recent impactful papers addressing this issue either directly or indirectly. It will be critical to maintain the forward progress made in addressing these challenges, while readying the field for big changes to come.
Under-recognized Cardiac Disease Burden in DDX3X Syndrome: Spectrum of Cardiovascular Abnormalities and Longitudinal Outcomes
Dhamija, Radhika, Rada, Lauren, Fittanto, Sarah , Johnson, Jonathan N. , Hagler, Donald J. , Stephens, Elizabeth H. , Gallego-Navarro, Carlos , Theis, Jeanne L. , Dhamija, Radhika , Schimmenti, Lisa A. , Thompson, Whitney S. , Niaz, Talha

No container title available | April 1, 2026 | Volume: No volume available | Issue: No issue available | Pages: No page available

10.21203/rs.3.rs-9059706/v1 Get It

Abstract Background DDX3X- syndrome is a rare neurodevelopmental disorder characterized by varying degrees of intellectual disability, predominantly affecting females. We present an institutional cohort supplemented by a systematic literature review, expanding the cardiovascular phenotype of DDX3X- syndrome. Methods We conducted a retrospective chart review of patients diagnosed with DDX3X -syndrome at Mayo Clinic. Additionally, we performed a systematic literature review to identify studies reporting cardiovascular abnormalities in patients with DDX3X -syndrome. Results A total of 200 patients with DDX3X -syndrome were analyzed, comprising 14 patients from our institutional cohort and 186 patients identified through a systematic review of 9 published studies. Our institutional cohort included 14 patients (12 females and 2 males) from 13 unrelated families diagnosed with DDX3X -syndrome, at a median age of 4.5 years (IQR 1.2–9.5). Echocardiogram was performed on nine patients, and cardiovascular abnormalities were found in 7 out of 9 patients who underwent echocardiography (78%), two of whom had major congenital heart defect (CHD) requiring surgical intervention. At the time of assessment, 13 individuals were still alive, while one had died at age six due to extracardiac complications. The systematic review included 9 studies involving 186 patients, of whom 32 (17.4%, 25 females and 7 males) had reported cardiovascular abnormalities, ranging from simple CHDs to more complex defects. Conclusion DDX3X -syndrome carries a significant cardiovascular burden, which is possibly higher than previously reported, including complex congenital heart disease requiring surgical repair. A thorough cardiovascular assessment, including an electrocardiogram and echocardiogram, should be universally recommended for all patients at the time of diagnosis.
SMARTER Education for a Global Transplant Workforce
Esquivel, Carlos O. , Smith, Sydney , Bajpai, Ruhaan, Johnson, Jonathan N. , McCulloch, Mignon , Oh, Jun, Pape, Lars, Bonham, Clark A. , Bartosh, Sharon , Marks, Stephen D. , Twombley, Katherine , Raina, Rupesh , Johnson, Jonathan , Bartosh, Sharon , Twombley, Katherine E , McCulloch, Mignon , Bajpai, Ruhaan

Pediatric Transplantation | November 10, 2025 | Volume: 29 | Issue: 8 | Pages: No page available

10.1111/petr.70222 Get It

ABSTRACT IPTA created the SMARTER Initiative to address persistent gaps in pediatric transplant education worldwide. Through webinars, podcasts, case discussions, and interactive resources, SMARTER provides trainees and allied professionals with accessible, peer‐reviewed content across all major organ systems. The program is designed for global reach, with downloadable modules, mobile compatibility, and recorded sessions to accommodate different regions and time zones. Since its launch, SMARTER has shown strong engagement, with fellows reporting that the platform helps them prepare for board exams, improve clinical decision‐making, and connect learning directly to patient care. Survey feedback highlights high satisfaction and identifies opportunities for further growth, such as expanded case‐based modules, procedural videos, and simulation exercises. By reducing disparities in transplant training and supporting collaboration, SMARTER is positioned to strengthen existing curricula and promote a better‐prepared, more globally connected transplant workforce.
Abstract 4367364: A Multicenter Friedreich Ataxia Registry Identifies Posterior Wall Thickness as a Predictor of Major Adverse Cardiac Events
Dedio, Anna, McSweeney, K., Fournier, Anne , Yoon, Grace , Payne, R. Mark , Cripe, Linda , Patel, Aarti , Johnson, Jonathan N. , Lynch, David T. , Tate, Barbara , Feng, Yixuan , Mercer‐Rosa, Laura , Lin, Kimberly Y. , Niaz, Talha , McCormack, Shana Erin , Tate, Barbara, Feng, Yixuan, Huang, Jing Yang

Circulation | November 3, 2025 | Volume: 152 | Issue: Suppl_3 | Pages: No page available

10.1161/circ.152.suppl_3.4367364 Get It

Background: Cardiac disease is the leading cause of premature mortality in Friedreich Ataxia (FA). However, validated prognostic indicators or early imaging biomarkers that can reliably predict cardiac events are lacking. To address this gap, we created a multicenter FA cardiac registry to characterize disease progression and identify early echocardiographic (echo) predictors of major adverse cardiac events (MACE). Methods: FA subjects from 6 North American centers with at least two echos performed ≥5 years apart were included. Demographics, FA-specific disease characteristics, and MACE (a composite of death, heart failure hospitalization, aborted sudden cardiac death, and/or life-threatening arrhythmia) were abstracted. Digital echo images were re-read at a centralized core lab. Paired T tests were utilized for comparison of the normally distributed first and second echo parameters, and logistic regression models were utilized to evaluate for predictors of MACE. Results: Of 115 subjects, 52 (45%) were female. Mean age at diagnosis was 10 ± 3 years, median GAA1 repeat length (a marker of genetic severity) was 700 (range 66–1200), and median age at first analyzed echo was 12 years (range 4-36). MACE occurred in 35 (30%) of the cohort. Serial echocardiograms demonstrated progressive worsening of multiple cardiac parameters over time, including markers of ventricular thickness and hypertrophy, chamber size, systolic function, and novel markers of atrial and ventricular strain (Table 1). On univariate analysis, several markers of hypertrophy and systolic function from the earliest analyzed echo predicted MACE. However, after adjusting for age of diagnosis, GAA1 repeat length, and collinearity among variables, only posterior wall thickness in diastole (PWTd) remained an independent predictor of MACE (odds ratio 1.8 per mm increase, 95% CI 1.1–3.3, p = 0.028). Conclusions: This multicenter FA registry identifies early posterior wall thickness as a significant and independent predictor of major adverse cardiac events in FA. Each millimeter increase in PWTd on early echo is associated with nearly double the odds of MACE. This commonly acquired parameter is often overlooked and may serve as a powerful early marker of cardiac risk. Further investigation of PWTd as a potential surrogate endpoint for therapeutic trials in FA is warranted.
Pediatric Heart Failure: A Practical Guide for Primary Care Providers Supporting Families Across the Care Continuum
Amdani, Shahnawaz , Puri, Kriti , Glickstein, Julie S. , Johnson, Jonathan N. , Harahsheh, Ashraf S. , Makhoul, Majd , Denfield, Susan W. , Glickstein, Julie , Harahsheh, Ashraf S , Makhoul, Majd , Spinner, Joseph A.

Children | September 25, 2025 | Volume: 12 | Issue: 10 | Pages: 1293

10.3390/children12101293 Get It

Background/Objectives: Pediatric heart failure (HF) is a complex clinical syndrome with diverse etiologies and presentations. Primary care providers (PCPs) are critical in early recognition, family education, and coordination of ongoing care in collaboration with pediatric cardiologists. This review provides a comprehensive guide for PCPs to understand the causes, symptoms, treatments, and longitudinal considerations for children with HF. Methods: We conducted a narrative review synthesizing published evidence and expert consensus guidelines, focusing on the clinical presentation, treatment options, and longitudinal care strategies in children with HF. Results: HF in children most commonly results from congenital heart disease and cardiomyopathy, but includes a wide range of etiologies. Presenting symptoms differ by age, with subtle signs often mistaken for common pediatric illnesses. Treatments range from disease-modifying medications to surgical and transplant therapies. Psychosocial support, mental health, and family-centered care are critical components of long-term management. Conclusions: PCPs are essential partners in the care of children with HF. A proactive, collaborative, and informed approach can improve quality of life, reduce hospitalizations, and support families navigating this challenging diagnosis.
Transplant Pharmacist Intervention During Pediatric Care Center Transfers: An Unaddressed Gap
Huntsman, R. G. , Fenske, Molly , Lemke, Adley , Schueler, Kerry, DiCarlo, Michele , Kolbet, Karen , McCord, Molly, Rosier, Ashley S. , Johnson, Jonathan N. , Ameduri, Rebecca , Bernard, Stacy A. , Lemke, Adley I , Fenske, Molly W , Huntsman, Rachel

Pediatric Transplantation | August 4, 2025 | Volume: 29 | Issue: 6 | Pages: No page available

10.1111/petr.70155 Get It

ABSTRACT Background Risk for medication error increases during care transitions. Error susceptibility increases in pediatrics due to age and weight‐based dosing. Governing bodies acknowledge errors endanger patients, and transplant pharmacotherapy experts are mandated by the Center for Medicare and Medicaid Services (CMS). Pharmacist‐led medication histories reduce errors; however, pharmacists' roles in the transitions of care between transplant centers are unaddressed by CMS. We assessed the impact of transplant pharmacist involvement in medication histories for pediatrics transitioning between transplant centers. Methods Pediatric patients pre‐ or post‐heart transplant transitioning to our center were proactively identified. Transplant pharmacists conducted medication histories by phone with caregivers and tracked discrepancies between existing medication lists and interview responses. Descriptive statistical analyses were completed. Results Of 27 patients identified, seven caregivers were uncontactable, one declined participation, and 19 underwent transplant pharmacist medication history. Medication list errors were detected in 100% of patients ( n = 19), with a median [IQR] of 5 [3–11] issues per patient. Of 122 issues, 72 (59%) were inaccurate or missing data, 17.2% ( n = 21) listed stopped drugs, 9.8% ( n = 12) revealed incorrect administration routes, 7.4% ( n = 9) were duplicate medications, and 6.6% ( n = 8) of errors were medications needing to be added. Corrections included updating 84 inaccuracies (68.8%); removing/adding drugs (30 [24.6%] and 8 [6.6%], respectively); and team communication. Conclusions Complex dosing strategies in pediatrics confer error vulnerability. Designing transition of care processes with transplant pharmacist involvement in medication histories can assist in ensuring medication list accuracy, thereby improving pediatric patient safety.
Successful Utilization of Organ Care System in Three Pediatric Heart Transplant Recipients
Yu, Liwei , Johnson, Jonathan N. , Daly, Richard C., Dearani, Joseph A. , Stephens, Elizabeth H. , Villavicencio, Mauricio A. , Reynolds, F.A., Ameduri, Rebecca , Reynolds, Frank A, Dearani, Joseph A.

Pediatric Transplantation | June 11, 2025 | Volume: 29 | Issue: 5 | Pages: No page available

10.1111/petr.70114 Get It

ABSTRACT Introduction Improving organ preservation is essential for expanding the donor pool and enhancing outcomes for pediatric transplant recipients. This report presents three pediatric patients who received donor hearts preserved using the Organ Care System (OCS). All donor hearts were prepared, placed, and monitored on OCS according to standard protocols. Heart function and myocardial edema were visually assessed during monitoring. Case Reports Patient 1: A 17‐year‐old female patient with hypertrophic cardiomyopathy utilized OCS technology due to donor distance. She experienced an uncomplicated post‐transplant course and was discharged on post‐transplant day 10. Patient 2: A 14‐year‐old male patient with complex congenital heart disease, palliated with Fontan circulation, underwent orthotopic heart transplantation (OHT) with OCS support due to both the complexity of the procedure and donor heart distance. His post‐transplant course was complicated by a revision of the ascending aorta anastomosis and prolonged milrinone infusion for diastolic dysfunction. He was discharged on post‐transplant day 31. Patient 3: A 16‐year‐old male patient with hypoplastic left heart syndrome, also palliated with Fontan circulation, underwent OHT using OCS technology due to the complexity of the surgical procedure. His post‐transplant recovery was unremarkable, and he was discharged on post‐transplant day 15. Conclusions All three pediatric patients demonstrated favorable short‐term outcomes using OCS technology. The OCS system facilitated shorter ischemic times despite the need for extended transport distances or complex surgical procedures. However, further studies with larger patient cohorts and longer follow‐up are needed to better understand the long‐term impact of OCS on pediatric heart transplantation outcomes.
Educational Gaps and Suggestions for Change for Pediatric Transplant Fellowship Training Based on Fellow Survey Responses
Gallegos, Flora R. , McCulloch, Mignon , Nair, Nikhil , Hinton, Jared , Twombley, Katherine , Johnson, Jonathan N. , Bonham, Clark A. , Preka, Evgenia , Bhaskar, Anchal, Hu, Jieji , Marks, Stephen D. , Esquivel, Carlos O. , Raina, Rupesh , Gallegos, Flora R , Hinton, Jared , Bartosh, Sharon , Hu, Jieji , Twombley, Katherine E , McCulloch, Mignon , Pape, Lars , Oh, Jun Seok , Bartosh, Sharon , Bhaskar, Anchal

Pediatric Transplantation | May 19, 2025 | Volume: 29 | Issue: 4 | Pages: No page available

10.1111/petr.70105 Get It

ABSTRACT Background Advancements in organ transplant technology are pushing global transplant capabilities to new heights. However, challenges persist in pediatric surgical and medical transplant fellowship training, primarily due to a limited number of adequate training programs and gaps in education. Addressing these gaps is essential for improving patient outcomes and advancing the field of pediatric transplantation. Methods An international survey was distributed to 416 pediatric transplant fellows via multiple global transplant associations. The 29‐question survey, available in English and Spanish, assessed current clinical knowledge, training satisfaction, and preferred learning formats. The survey received responses from 237 pediatric transplant fellows. Results One of the key findings was that respondents felt most confident in their pre‐transplantation clinical knowledge. About 75.5% of fellows reported being extremely or very aware of pre‐transplant workups and assessments. However, significant gaps were identified in other areas of training. Notably, 24% of respondents felt extremely knowledgeable about the side effects of immunosuppression, and only 22.8% were very confident in managing acute rejection. Fellows expressed strong interest in dynamic educational formats, particularly clinical case discussions (88.8%). Preferred methods to enhance training included continuing medical education (64.6%), hands‐on workshops, and support for transition protocols and psychosocial counseling. Conclusion This global survey highlights critical educational gaps in pediatric transplant fellowship training and identifies preferred learning methods among fellows. Targeted improvements such as standardized curricula, case‐based learning, interdisciplinary collaboration, and accessible continuing education are essential to enhance training. These strategies will ensure that future transplant professionals are well‐equipped to deliver high‐quality care across diverse healthcare settings.
Combined Heart and Liver Transplantation in the Failing Fontan: Systematic Review and Single-arm Meta-analysis
Vizentin, Vanessa Karlinski , Bulhões, Elísio , Ameduri, Rebecca , Johnson, Jonathan N. , Karlinski Vizentin, Vanessa, Ferreira Félix, Iuri, Antunes, Vânio , Félix, Iuri Ferreira , Mesquita, Cynthia Florêncio de

Transplantation | May 5, 2025 | Volume: 109 | Issue: 11 | Pages: 1783-1791

10.1097/tp.0000000000005400 Get It

Background. The Fontan procedure has transformed the management of congenital heart defects characterized by single ventricle physiology, yet it predisposes individuals to Fontan-associated liver disease. Combined heart and liver transplantation (CHLT) emerges as a therapeutic option, but evidence of its efficacy and safety remains limited. This study aimed to comprehensively evaluate CHLT in Fontan patients, focusing on patient characteristics, perioperative outcomes, and posttransplant morbidity and mortality. Methods. Following Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines, a systematic search of PubMed, Embase, and the Cochrane Central Register of Controlled Trials was conducted. Studies meeting the intervention of CHLT in Fontan patients were included, and data were collected and synthesized using proportion meta-analysis techniques. Statistical analysis was carried out using R software. Results. Four studies met inclusion criteria, comprising 67 Fontan patients undergoing CHLT. All included studies were observational retrospective cohorts performed in the United States. The 1-y survival rate post-CHLT was 88% (95% confidence interval [CI], 70%-98%). Liver graft rejection rates were low, 4% (95% CI, 0%-22%), and no heart graft rejection greater than mild was reported. Postoperative complications included acute kidney injury 75% (95% CI, 50%-93%), temporary dialysis 27% (95% CI, 9%-51%), neurologic events 7% (95% CI, 0%-26%), infection 23% (95% CI, 3%-55%), and unplanned medical procedures 40% (95% CI, 23%-59%). Conclusions. CHLT in Fontan patients demonstrates promising survival rates, but graft rejection and postoperative complications pose challenges. The rate of renal complications is particularly notable and requires further evaluation. Future research should prioritize comparative different management strategies and long-term follow-up to refine protocols and optimize outcomes.
Fontan-Associated Liver Disease
Hilscher, Moira , Johnson, Jonathan N.

Seminars in Liver Disease | March 14, 2025 | Volume: 45 | Issue: 01 | Pages: 114-128

10.1055/a-2556-4897 Get It

Fontan-associated liver disease (FALD) occurs in all patients who have undergone Fontan palliation for functional single ventricle congenital heart defects. While liver fibrosis is universal in patients who have undergone Fontan palliation, FALD may lead to more serious consequences including portal hypertension, cirrhosis, and hepatocellular carcinoma. Scientific studies of the pathophysiology and clinical management of FALD have been limited to date by the heterogeneous nature of the disease, relatively small population of patients with Fontan physiology, and inaccuracy of noninvasive staging tests. As survival after the Fontan procedure improves, the population of adults with Fontan physiology is growing, leading to more severe extracardiac complications related to the Fontan circulation and growing demand for heart and liver transplantation. The accurate evaluation, staging, and management of FALD comprises a clinical challenge which requires expert multidisciplinary input.