Long-term support with milrinone prior to cardiac transplantation in a neonate with left ventricular noncompaction cardiomyopathy

Neonatal Non-compacted Cardiomyopathy: Predictors of Poor Outcome

Non-compacted cardiomyopathy (NCM) is a heterogenous myocardial disorder. Although much has been published in recent years, little is known about NCM in the neonatal period. The objective of this study is to characterize the involvement of newborns affected with NCM and to identify risk factors associated with increased mortality. This is a retrospective study including all neonates diagnosed with NCM between 2006 and 2018. Diagnosis was based on echocardiographic findings. Data were collected regarding prenatal history, gestational age and weight at birth, gender, age at diagnosis, left or biventricular involvement and associated malformations, medical and surgical treatments, and evolution. Fourteen patients were included. The median follow-up duration was 34 months (range 1-87 months). The left ventricular apex and lateral wall were involved in all cases (100%). Thirteen patients (92.8%) had other associated heart malformations. Six patients (42.8%) died during the follow-up period. Patients who had biventricular involvement and poor ventricular function presented a higher risk of death. The main cause of death was ventricular dysfunction (5/6 [83.3%]). During follow-up, eight patients (57.1%) underwent surgery for their cardiac malformations, without higher mortality. NCM must be included in the differential diagnosis of neonatal cardiomyopathy. The higher mortality observed in our series is related not only to the high association with congenital heart disease, but also to a greater presence of early and severe left ventricular dysfunction. We did not find that patients who underwent surgery with cardiopulmonary bypass had worse outcomes.

Safety and efficacy of the off-label use of milrinone in pediatric patients with heart diseases

Background and Objectives

Milrinone is often used in children to treat acute heart failure and prevent low cardiac output syndrome after cardiac surgery. Due to the lack of studies on the long-term milrinone use in children, the objective of this study was to assess the safety and efficacy of the current patterns of milrinone use for ≥3 days in infants and children with heart diseases.

Subjects and Methods

We retrospectively reviewed the medical records of patients aged <13 years who received milrinone for ≥3 days from January 2005 to December 2012. Patients' characteristics including age, sex, height, weight, and body surface area were recorded. The following parameters were analyzed to identify the clinical application of milrinone: initial infusion rate, maintenance continuous infusion rate, total duration of milrinone therapy, and concomitantly infused inotropes. The safety of milrinone was determined based on the occurrence of adverse events such as hypotension, arrhythmia, chest pain, headache, hypokalemia, and thrombocytopenia.

Results

We assessed 730 admissions (684 patients) during this period. Ventricular septal defects were the most common diagnosis (42.4%) in these patients. Milrinone was primarily used after cardiac surgery in 715 admissions (97.9%). The duration of milrinone treatment varied from 3 to 64.4 days (≥7 days in 149 admissions). Ejection fraction and fractional shortening of the left ventricle improved in patients receiving milrinone after cardiac surgery. Dose reduction of milrinone due to hypotension occurred in only 4 admissions (0.5%). Although diverse arrhythmias occurred in 75 admissions (10.3%), modification of milrinone infusion to manage arrhythmia occurred in only 3 admissions (0.4%). Multivariate analysis indicated that the development of arrhythmia was not influenced by the pattern of milrinone use.

Conclusion

Milrinone was generally administered for ≥3 days in children with heart diseases. The use of milrinone for ≥3 days was effective in preventing low cardiac output after cardiac surgery when combined with other inotropes, suggesting that milrinone could be safely employed in pediatric patients with heart diseases.

Heart Failure Treated with Low-dose Milrinone in a Full-term Newborn

A term newborn with a hypocontractile myocardium complicating persistent pulmonary hypertension of the newborn was successfully treated with a low-dose phosphodiesterase III inhibitor milrinone. Echocardiography diagnosed heart failure with a left ventricular ejection fraction of 35% and a left ventricular shortening fraction of 18% and severe persistent pulmonary hypertension of the newborn with oxygenation index of 28. Milrinone was started at an initial dose of 50 mcg/kg, followed by continuous infusion of 0.20 mcg/kg/min. With lowdose milrinone oxygenation index decreased to 3 within 6 hours, left ventricular ejection fraction and left ventricular shortening fraction increased to 57%, and 30%, respectively. Low doses of milrinone might be promising in the treatment of heart failure and persistent pulmonary hypertension of the newborn in term newborns.

Left ventricular non-compaction and its cardiac and neurologic implications

Left ventricular non-compaction, also known as left ventricular hypertrabeculation (LVHT), is a morphological abnormality of the left ventricular myocardium, characterised by a meshwork of myocardial strings, interlacing, and orderless in arrangement. LVHT is most frequently located in the apex and the lateral wall and may occur with or without other congenital or acquired cardiac abnormalities. LVHT is believed to be congenital in the majority of the cases but may develop during life in single cases (acquired LVHT). Congenital LVHT is believed to result from defective late-stage embryonic development of the myocardial architecture. The pathogenesis of acquired LVHT remains speculative. LVHT is most frequently found on transthoracic echocardiography and cardiac MRI but may be visualised also with other imaging techniques. In the majority of the cases, LVHT is associated with hereditary cardiac, neuromuscular, non-cardiac/non-muscle disease, or chromosomal aberrations. In the majority of the cases, LVHT is complicated by ventricular arrhythmias, systolic dysfunction, cardiac embolism, or sudden cardiac death. LVHT per se does not require a specific treatment. Only in case of complications, such as ventricular arrhythmias, cardioembolism, or systolic dysfunction, adequate therapy is indicated. Though initially assessed as poor, the prognosis of LVHT has meanwhile improved, most likely due to the increased awareness for the abnormality and the timely administration of adequate therapy.