075 - Right ventricular to left ventricular diameter ratio in neonates with lower urinary tract obstruction

Publication Number: 75.6447

Judith Leyens, Department of Neonatology and Pediatric Intensive Care, University of Bonn, Germany; Division of Neonatology, Department of Pediatrics, BC Women´s and Children´s Hospital, University of British Columbia, Canada, Vancouver, BC, Canada; Bartolomeo Bo, Department of Neonatology and Pediatric Intensive Care, Bonn, Nordrhein-Westfalen, Germany; Lukas Schroeder, University of Bonn, Department for Neonatology and Pediatric Intensive Care Medicine, Bonn, Nordrhein-Westfalen, Germany; Andreas Müller, University Children's Hospital Bonn, Germany, Bonn, Nordrhein-Westfalen, Germany; Florian Kipfmueller, University Children‘s Hospital Bonn, Bonn, Nordrhein-Westfalen, Germany

Background: Approximately 2.2 in 10,000 neonates are born with lower urinary tract obstruction (LUTO), and over 90% of affected infants are male. The most common cause of LUTO are posterior urethral valves. The diagnosis is usually established until the second trimester of pregnancy. The obstruction causes urinary retention, and consecutively a megacystis and renal dysplasia. The diminished urine output results in oligohydramnios and pulmonary hypoplasia. In the long term, 15-20% of patients develop chronic kidney disease requiring dialysis or renal transplantation in infancy. Early intrauterine vesicoamniotic shunting may increase survival, but the effect on renal function remains uncertain. The main causes for postnatal mortality and morbidity are pulmonary hypoplasia and hypertension. Cardiopulmonary interactions have been well described in infants with congenital diaphragmatic hernia, in which an end-diastolic right-ventricular to left-ventricular diameter ratio (RVD/LVD-ratio) over 1.1 has been associated with poor outcome.

Objective: Our study aims to investigate early RVD/LVD -ratios in infants with LUTO as a potential outcome parameter.

Design/Methods: Retrospective monocentric cohort study of prenatally diagnosed infants with LUTO from January 2013 and January 2024. The study design is demonstrated in Figure 1. RVD/LVD -ratios, cardiac, and renal laboratory markers were analyzed on day of life 1 and 6-8. Infants with RVD/LVD -ratios above and below 1.1 on the first day of life were compared using Fisher´s exact test and independent samples t-test, as appropriate.

Results: A total of 33 patients were included. Table 1 demonstrates the baseline demographics, and comparison of RVD/LVD -ratios (measurement shown in Figure 2). Baseline demographics were similar except for rate and length of invasive ventilation (p=0.042 and p=0.039, respectively). Infants with an RVD/LVD below 1.1 demonstrated more significant markers of renal impairment.

Conclusion(s): Only few studies exist on cardiopulmonary interactions in infants with LUTO. Unexpectedly, infants with RVD/LVD below 1.1 showed a trend towards more severe pulmonary disease and renal impairment. Possible causes may be an increased afterload and LVD diameter due to enlarged kidneys and bladder causing arterial compression. Additionally, vasoactive mediators potentially impair cardiac remodeling and cause diastolic dysfunction. Our cohort also has a high rate of prenatal intervention that might alleviate right ventricular impairment. Larger prospective studies are warranted to validate these findings and further explore the cardiac-pulmonary-renal axis in LUTO.

Table 1
Table 1_LUTOpatientcharacteristics_PAS.pdfOverview of demographics and analyzed parameters for overall cohort, and for patients with RVD/LVD-ratio >1.1 and <1.1 on day of life 1 (1) and 6 – 8 (2). Results are reported as absolute numbers (n) with %, mean ± standard deviation, or median with IQR. A p-value <0.05 is considered statistically significant and marked*.
BUN: blood urea nitrogen; BW: birth weight; ECMO: extracorporeal membrane oxygenation; d: days; GA: gestational age; HC: head circumference; IV: invasive ventilation; IQR: interquartile range; LUTO: lower urinary tract obstruction; LVD: left ventricular diameter; NO: nitric oxide; NTproBNP: N-terminal pro b-type natriuretic peptide; RVD: right ventricular diameter; UA: umbilical artery; wk: weeks.


Figure 1
Figure1_LUTOflowchart_PAS.pdfFlow chart of the applied retrospective study design demonstrating data acquisition and analysis of newborn patients with lower urinary tract obstruction (LUTO).
* alternative diagnoses consisted of vesicoureteral reflux (n=2), no pathological findings (n=1), vesicoureteric junction stenosis (n=1), fetal megacystis of unknown origin (n=1), megacystis microcolon intestinal hypoperistaltis syndrome (n=1), complex bladder anomaly with duplication of the urinary bladder and urachal cyst (n=1).


Figure 2
(A) Echocardiographic apical four chamber view with exemplary RVD and LVD measurement. (B) Postnatal chest Xray of a neonate with LUTO and anhydramnios demonstrating thorax and lung hypoplasia. The baby required a chest drain for right-sided pneumothorax. (C) Postnatal urinary tract ultrasound of a LUTO neonate with a thick-walled bladder. (D) Postnatal urinary tract ultrasound in a LUTO neonate shows a small kidney with pelvic dilatation and loss of corticomedullary differentiation. (E) In this LUTO neonate, the hypoplastic right-sided kidney shows severely reduced corticomedullary differentiation and is barely distinguishable from the surrounding tissue. _x000B_AG: adrenal gland; B: bladder; K: kidney; L: liver; LUTO: lower urinary tract obstruction; LVD: end-diastolic left-ventricular diameter; RVD: end-diastolic right-ventricular diameter.