John David Corcoran

Assessment of myocardial performance in preterm infants less than 29 weeks gestation during the transitional period.

BACKGROUND The transitional circulation and its effect on myocardial performance are poorly understood in preterm infants. AIMS We assessed myocardial performance in infants less than 29 weeks gestation in the first 48 h of life using a comprehensive echocardiographic assessment. DESIGN Infants <29 weeks gestation were prospectively enrolled. Small for gestation, infants on inotropes and/or inhaled nitric oxide and septic infants were excluded. Conventional echocardiography, left ventricular (LV), septal and right ventricular (RV) tissue Doppler imaging (TDI) and tissue Doppler-derived strain and strain rate (SR), tricuspid annular plane systolic excursion (TAPSE) and global RV fractional area change (FAC) were assessed at a median of 10 and 45 h post-delivery. RESULTS Fifty-four infants with a median [IQR] gestation and birth weight of 26.5 weeks [25.8-28.0 weeks] and 915 g [758-1142 g] were included. There was no change in shortening or ejection fraction across the two time points. Systolic and diastolic TDI of the LV, septum and RV increased across the two time points (all p values ≤ 0.01). There was an increase in septal peak systolic and early diastolic SR (p=0.002). Septal systolic strain and late diastolic SR did not change. With the exception of RV strain and early diastolic SR, all RV functional parameters including SR, late diastolic SR, TAPSE, and FAC increased across the two time points (all p values<0.01). CONCLUSION Describing the normal hemodynamic adaptations in stable preterm infants during the transitional period provides the necessary information for the assessment of those parameters in various disease states.

The effect of milrinone on right and left ventricular function when used as a rescue therapy for term infants with pulmonary hypertension.

INTRODUCTION Milrinone may be an appropriate adjuvant therapy for infants with persistent pulmonary hypertension of the newborn. We aimed to describe the effect of milrinone administration on right and left ventricular function in infants with persistent pulmonary hypertension not responding to inhaled nitric oxide after 4 hours of administration. MATERIALS AND METHODS This is a retrospective review of infants born after or at 34 weeks of gestation with persistent pulmonary hypertension who received milrinone treatment. The primary endpoint was the effect of milrinone on myocardial performance and haemodynamics, including right and left ventricular outputs, tissue Doppler velocities, right ventricle and septal strain, and strain rate. Secondary endpoints examined included duration of inhaled nitric oxide and oxygen support. RESULTS A total of 17 infants with a mean (standard deviation) gestation and birth weight of 39.8 (2.0) weeks and 3.45 (0.39) kilograms, respectively, were included in the study. The first echocardiogram was performed 15 hours after the commencement of nitric oxide inhalation. Milrinone treatment was started at a median time of 1 hour after the echocardiogram and was associated with an increase in left ventricular output (p=0.04), right ventricular output (p=0.004), right ventricle strain (p=0.01) and strain rate (p=0.002), and left ventricle s` (p<0.001) and a` (p=0.02) waves. There was a reduction in nitric oxide dose and oxygen requirement over the subsequent 72 hours (all p<0.05). CONCLUSION The use of milrinone as an adjunct to nitric oxide is worth further exploration, with preliminary evidence suggesting an improvement in both oxygenation and myocardial performance in this group of infants.

Treatment of premature infants with pulmonary hypertension and right ventricular dysfunction with milrinone: a case series

Objective:Milrinone has been proposed as an effective treatment for pulmonary hypertension (PH) and right ventricular (RV) dysfunction. We aimed to determine the effect of milrinone therapy on clinical and echocardiography parameters of PH in preterm infants with elevated pulmonary pressures.Study Design:A retrospective case review was conducted on infants <32 weeks gestation who received milrinone for the treatment of PH and reduced RV function. Echocardiographic data were collected before and after treatment with milrinone, and serial clinical parameters were recorded over a 72h  period.Result:Seven infants met the inclusion criteria with a median gestation and birth weight of 27.3 weeks and 1140 g, respectively. Four infants had a diagnosis of pulmonary hypoplasia with PH, and three infants were recipients in twin-to-twin transfusion syndrome who also developed PH. Nitric oxide was used in six infants before commencement of milrinone. Milrinone was commenced at a dose of 0.33 μg kg−1 min−1 to 0.5 μg kg−1 min−1 and continued for a median duration of 70 h. Use of milrinone was associated with a fall in oxygenation index and inhaled nitric oxide dose. Following an initial fall in blood pressure over the first 6 h, there was an increase in blood pressure over the subsequent 72 h. Echocardiographic data demonstrated an increase in indicators of myocardial performance and PH. One infant died before discharge.Conclusion:This case series suggests that milrinone may be a useful therapy for premature infants with echocardiography findings of PH and/or RH dysfunction. This data support the need for a randomised control trial to confirm its efficacy.

Myocardial assessment using tissue doppler imaging in preterm very low-birth weight infants before and after red blood cell transfusion

Objective:To investigate myocardial velocities in anemic very low-birth weight (VLBW) preterm infants, pre and post red blood cells transfusion using tissue Doppler imaging echocardiography.Study design:Forty-eight VLBW preterm infants⩽34 weeks and>2 weeks old were prospectively divided: Transfused symptomatic infants (Hematocrit (Hct)<0.30 (n=32)) and non transfused asymptomatic controls (control 1, Hct >0.30 (n=9) and control 2, Hct <0.30 (n=7)). Echocardiography was performed before and 3–5 days after transfusion in the transfused, and the controls were studied at similar intervals. Non parametric tests were used for statistical analysis.Result:Left ventricular (LV) systolic velocity increased (transfused (4.6±0.70 vs 6.0±0.65, P<0.01)) as did LV diastolic velocities (P<0.01) without significant difference over time in each control. The percentage change in LV velocity following transfusion correlated negatively (ρ=0.36) with pre transfusion Hct.Conclusion:There is a significant increase in myocardial performance following transfusion, which is related to the severity of the anemia.

Transcutaneous bilirubin – comparing the accuracy of BiliChek® and JM 103® in a regional postnatal unit

Objective. Transcutaneous bilirubin (TcB) has the potential to reduce serum bilirubin sampling. During a recent survey on the use of TcB in postnatal units in the Republic of Ireland, we identified that only 58% of the 19 units were using TcB and that only two devices were in use, the BiliChek® and JM 103®. We aimed to evaluate and compare these two devices in a regional postnatal unit. Methods. To evaluate and compare the accuracy of the BiliChek® and JM 103®, we studied simultaneous TcB and total serum bilirubin (TSB) measurements from a population of jaundiced term and near term infants. We evaluated each device with regard to correlation with TSB and potential to safely reduce serum bilirubin testing. Results. Both TcB devices strongly correlated with TSB (r = 0.88 for BiliChek® and r = 0.70 for JM 103®). The BiliChek® and JM 103® were accurate up to cut-off values of 200 μmol/L and 180 μmol/L, respectively. Using Bhutanis nomogram, 100% sensitivity was achieved using the 75th percentile for BiliChek® and the 40th percentile for JM 103®. Conclusion. Both TcB devices correlated closely with moderately increased TSB levels and are suitable screening tools to identify jaundiced infants that require a serum bilirubin, with upper limit cut-off values. Both devices reduced the need for TSB levels. We found the BiliChek® slightly more accurate than the JM 103® for our study population. TcB however, is not in widespread use.

The effect of antenatal magnesium sulfate on left ventricular afterload and myocardial function measured using deformation and rotational mechanics imaging

Objective:Assess the effect of antenatal magnesium sulfate (MgSO4) on left ventricular function measured using deformation and rotational mechanics imaging.Study Design:Infants who received MgSO4 were matched for gestation, birth weight and mode of delivery with controls. Echocardiography was carried out on days 1 and 2 to measure left ventricle longitudinal strain (LV LS), twist, untwist rate, ejection fraction (EF), and systemic vascular resistance (SVR).Results:Thirty-eight infants with a median gestation and birth weight of 27.1 weeks and 923 g were included. On day 1, the MgSO4 group (n=19) had a lower SVR and higher LV LS, EF, twist and untwist rate than the Control group (n=19) (all P<0.05). There were no differences between the groups on day 2.Conclusion:Antenatal MgSO4 administration is associated with a lower SVR and higher myocardial function on day 1 in preterm infants <29 weeks gestation.