Changes in hemodynamics after closure of the ductus arteriosus in preterm infants

Abstract

We read with interest the article by Noori et al1Noori S. Friedlich P. Seri I. Wong P. Changes in myocardial function and hemodynamics after ligation of the ductus arteriosus in preterm infants.J Pediatr. 2007; 150: 597-602Abstract Full Text Full Text PDF PubMed Scopus (118) Google Scholar on changes in myocardial function and hemodynamics after ligation of the ductus arteriosus in preterm infants. Noori et al found that during the first 24 hours after ligation, 35% of the patients required at least a 25% increase in the dosage of dopamine to maintain blood pressure (BP) in the normal range. However, among the various indices of cardiac function evaluated in these patients, none were found to predict an increase in the need for vasopressor support. This is relevant, considering the paucity of information in the literature on the effect of PDA medical or surgical closure on systemic hemodynamics. We studied the changes in BP and in urinary excretion rates of endothelin-1 (ET-1) and vasopressin (AVP) after treatment of PDA with nonsteroidal anti-inflammatory drugs (NSAIDs) in a cohort of 56 preterm infants (<32 weeks gestation) diagnosed with respiratory distress syndrome. We found that after medical PDA closure (60.8%), both systolic and diastolic BP increased significantly, maintaining a stable pulse pressure. When pharmacologic closure failed, the trend (nonsignificant) was for a more consistent increase in systolic BP than in diastolic BP, along with a statistically significant widening pulse pressure. In addition, urinary ET-1 excretion rates decreased significantly after PDA closure (UET-1/Ucr, 0.15 ± 0.07 vs. 0.10 ± 0.05 fenton/mmol; P < .005), whereas they remained elevated if pharmacologic therapy failed. Urinary AVP excretion rates decreased (albeit not significantly) after therapy and was uninfluenced by the efficacy of treatment. ET-1 and AVP are potent vasoconstrictors that play a fundamental physiological role in circulatory adaptation to extrauterine life and in the maintenance of BP.2Endo K. Ayusawa M. Minato M. Takalda M. Takahashi S. Harada K. Physiologic significance of nitric oxide and endothelin-1 in circulatory adaptation.Pediatr Int. 2000; 42: 36-40Crossref Google Scholar, 3Tsukahara H. Sekine K. Miura M. Todoroki Y. Ohshima Y. Hiraoka M. et al.Vasoactive and natriuretic mediators in umbilical cord blood: a report of our observation and review of the literature.Early Hum Dev. 2002; 69: 57-64Abstract Full Text Full Text PDF PubMed Scopus (14) Google Scholar Elevated ET-1 excretion rates in preterm infants who are unresponsive to NSAIDs indicate the need to extend the investigation after surgical PDA ligation into an area in which changes in myocardial function and hemodynamics have shown to have clinical significance.1Noori S. Friedlich P. Seri I. Wong P. Changes in myocardial function and hemodynamics after ligation of the ductus arteriosus in preterm infants.J Pediatr. 2007; 150: 597-602Abstract Full Text Full Text PDF PubMed Scopus (118) Google Scholar ReplyThe Journal of PediatricsVol. 152Issue 4PreviewWe thank Zanardo et al for their comments on our article.1 In their comments, they refer to their finding that serum levels of the vasoconstrictor hormones endothelin-1 and vasopressin change after pharmacologic treatment of patent ductus arteriosus (PDA) with cyclooxygenase (COX) inhibitors. They propose that these hormonal changes might reflect the hemodynamic adaptation to ductal shunting. Although this certainly is a possibility, we would like to point out that because locally generated vasodilating and diuresis-promoting prostaglandins naturally counterbalance the vascular and renal actions of vasopressin and endothelin-1, the use of COX inhibitors likely has an effect on the urinary excretion of these vasoconstrictor hormones independent of the changes in hemodynamics that occur. Full-Text PDF