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Objective: Immature platelet counts (IPC) may prove useful in guiding platelet transfusion management in preterm neonates. However, the relationship between IPCs and thrombopoietin (Tpo) concentrations has not been evaluated in preterm neonates. Methods: Prospective cohort study in thrombocytopenic (n = 31) and non-thrombocytopenic very low birth weight (VLBW) infants (n = 38), and healthy term neonates (controls; n = 41). Absolute platelet counts (APCs), IPCs, and Tpo concentrations were assessed by a fully-automated hematological analyzer (IPC, APC) and by ELISA (Tpo concentrations) in parallel on day 1 of life (d1), d3, and d7. Results: In healthy term neonates, APCs remained stable between d1 and d3. In non-thrombocytopenic VLBW infants, APCs increased from d1 to d7, while in the thrombocytopenia group, APCs declined from d1 to d3, before they slightly increased again by d7. Median IPCs were similar in healthy term vs. non-thrombocytopenic VLBW infants and remained stable between d1 and d3 (p > 0.05). Notably, IPCs significantly increased between d3 and d7 in both non-thrombocytopenic and thrombocytopenic VLBW infants. However, in thrombocytopenic VLBW infants, IPC values were significantly lower at each time point as compared to non-thrombocytopenic VLBWs (p < 0.001). In each subgroup, Tpo concentrations increased from d1 to d3. The median Tpo concentrations were significantly higher in thrombocytopenic as compared to non-thrombocytopenic VLBW infants at d3 (p = 0.01) and d7 (p = 0.002). Discussion: Term infants, thrombocytopenic, and non-thrombocytopenic preterm infants display similar developmental changes in indices of megakaryopoietic activity. In thrombocytopenic preterm infants, however, the responsive increases in Tpo and immature platelets appear to be developmentally limited.

Platelets are critically involved in murine patent ductus arteriosus (PDA) closure. To date, the clinical significance of these findings in human preterm infants with PDA is still controversial. We discuss the available study data on the role of platelets for PDA closure in preterm infants: Several mostly retrospective studies have yielded conflicting results on whether thrombocytopenia contributes to failed spontaneous ductal closure. The same applies to investigations on the role of thrombocytopenia as a risk factor for unsuccessful ductus arteriosus closure by pharmacological treatment with cyclooxygenase inhibitors. Nonetheless, recent meta-analyses have concluded that thrombocytopenia constitutes an independent risk factor for both failed spontaneous and pharmacological PDA closure in preterm infants. However, the available investigations differ in regard to patient characteristics, diagnostic strategies, and treatment protocols. Several studies suggest that impaired platelet function rather than platelet number is critically involved in failure of ductus arteriosus closure in the preterm infant. A recent randomized-controlled trial on platelet transfusions in preterm infants with PDA failed to show any benefit for liberal vs. restrictive transfusion thresholds on PDA closure rates. Importantly, liberal transfusions were associated with an increased rate of intraventricular hemorrhage, and thus should be avoided. In conclusion, the available evidence suggests that thrombocytopenia and platelet dysfunction contribute to failure of spontaneous and pharmacological PDA closure in preterm infants. However, these platelet effects on PDA seem to be of only moderate clinical significance. Furthermore, platelet transfusions in thrombocytopenic preterm infants in order to facilitate PDA closure appear to cause more harm than good.

Im letzten Jahrzehnt konnte ein Paradigmenwandel im Management Frühgeborener mit persistierendem Ductus arteriosus (PDA) hin zu einer selteneren und weniger invasiven Therapie beobachtet werden. Dennoch legen mehrere Beobachtungen einen therapeutischen Benefit einer PDA-Therapie bei ausgewählten Frühgeborenen nahe. Die Kenntnis spezifischer Risikofaktoren stellt eine Voraussetzung für die Entwicklung einer individuell-adaptierten PDA-Therapie dar. Die vorliegende Arbeit ergänzt die verfügbaren Daten zur klinischen Bedeutung einer Thrombozytopenie als Riskofaktor für ein Ausbleiben des PDA-Verschlusses. So kann ein Einfluss der Thrombozytenzahl innerhalb der ersten Lebenswoche auf den pharmakologischen PDA-Verschluss gezeigt werden. Zudem ist eine niedrige Anzahl insbesondere reifer Thrombozyten mit einem Ausbleiben des PDA-Verschlusses in der ersten Lebenswoche assoziiert. Hingegen zeigte sich kein Einfluss des zusätzlich untersuchten VEGF Polymorphismus rs2010963 auf die PDA-Verschlussrate. In der Regel erfolgt eine PDA-Therapie primär pharmakologisch mittels Indometacin oder Ibuprofen. Paracetamol bietet eine neue zusätzliche Option auch in der späten „Rescue“-Therapie des PDA. Die vorliegende Arbeit präsentiert die diesbezüglichen Erfahrungen aus der eigenen Klinik. Immer häufiger werden Frühgeborene nach medikamentöser Therapie mit hämodynamisch nicht signifikantem PDA nach Hause entlassen. In der vorliegenden Arbeit wird gezeigt, dass dieses Vorgehen unter regelmäßiger kinderkardiologischer Kontrolle als sicher anzusehen ist. Für den definitiven Ductusverschluss stehen die chirurgische Ligatur und neuerdings auch katheterinterventionelle Verfahren zur Verfügung. Die PDA-Ligatur wird insbesondere im Hinblick auf mögliche respiratorische Langzeitfolgen kontrovers diskutiert. Daher wurden Lungenfunktionsanalysen bei Frühgeborenen nach erfolgreicher pharmakologischer Ductustherapie und nach sekundärer chirurgischer Ligatur durchgeführt. Die hier vorliegende Arbeit diskutiert die Ergebnisse der zusammengefassten Publikationen und ihre Implikationen für die PDA-Therapie sehr unreifer Frühgeborener und die weitere Forschung.

Background There is only limited experience with wearable cardioverter-defibrillators (WCD) in pediatric patients. We report on the successful application of a WCD in an adolescent patient with hypertrophic cardiomyopathy and myocardial bridging. Case presentation A 15-year-old girl presented with a history of recurrent syncope, dyspnea, and vertigo with exercise. Diagnostic work-up revealed non-obstructive hypertrophic cardiomyopathy and signs of myocardial ischemia with exercise. Given this high-risk constellation, the patient was scheduled for prophylactic implantation of an implantable cardioverter-defibrillator (ICD). One month after initial presentation and days prior to the planned ICD implantation, the patient collapsed during an episode of sustained ventricular tachycardia (VT) while running. VT was terminated by WCD shock delivery. Following this event, computerized tomography scan revealed myocardial bridging of the left anterior descending coronary artery causing a 90% stenosis in systole. After coronary surgery, life threatening arrhythmias have not recurred, but due to progressive heart failure, the patient underwent successful heart transplantation after 2 years. Conclusions The reported case highlights the importance and applicability of WCDs and the potentially malign nature of myocardial bridging in pediatric high-risk patients.

Supplemental Material for Ventricular–ventricular interaction variables correlate with surrogate variables of clinical outcome in children with pulmonary hypertension by Martin Koestenberger, Hannes Sallmon, Alexander Avian, Massimiliano Cantinotti, Andreas Gamillscheg, Stefan Kurath-Koller, Sabrina Schweintzger and Georg Hansmann in Pulmonary Circulation