Serial Pulsed Doppler Assessment of Pulmonary Artery Pressure in Very Low Birth-Weight Infants

We assessed pulmonary artery pressure (PAP) during the early neonatal period in very low birth-weight (VLBW) infants using serial echocardiographic measurements of the ratio of the pulmonary artery acceleration time to the right ventricular ejection time corrected by heart rate [AT:RVET(c)]. Eighty-four VLBW infants weighing less than 1500 g were examined using serial color Doppler echocardiography from 3 hours to day 7 after birth. The AT:RVET(c) of infants born after 30 weeks of gestation showed a rapid, significant increase during the early neonatal period, whereas those of the groups born at less than 30 weeks showed no significant increase before day 14. At 24 hours after birth, the AT:RVET(c) values of VLBW infants did not correlate well with either the ratio of the right preejection period to the right ventricular ejection time on M-mode echocardiography or the pressure gradient between the right ventricle and the right atrium, as estimated by tricuspid regurgitation on pulsed Doppler echocardiography. The AT:RVET(c) value for the chronic lung disease (CLD) group did not differ significantly from that for the oxygen-dependent group at any assessment point. During the early neonatal period, the AT:RVET(c) of VLBW infants, as calculated by pulsed Doppler echocardiography, differed with their gestational age and did not appear to correlate well with PAP. Our data also suggest that AT:RVET(c) values may not be a good predictor of the subsequent occurrence of CLD in VLBW infants.     

Duplex versus Unguided Pulsed Doppler Measurements of Right Ventricular Output in Newborn Infants

ABSTRACT. Noninvasive measurement of pulmonary artery blood flow has widespread implications for management of newborn infants requiring intensive care. Using a precordial, unguided, single Doppler technique, we evaluated right ventricular output in 26 preterm and 16 term infants without cardiopulmonary problems and compared it with right ventricular output obtained by duplex Doppler scanning and left ventricular output measured by a suprasternal single Doppler approach. Weights ranged from 1120 to 3960 g and postconceptional ages from 29 to 42 weeks. Unguided measurements of left and right ventricular output and guided and unguided measurements of right ventricular output were highly correlated (r=+0.92 and +0.95 respectively, p<0.001). The precordial single Doppler technique offers a reliable noninvasive estimate of right ventricular output in preterm and term newborn infants.     

Postnatal Left Ventricular Contractility in Very Low Birth Weight Infants

The objective of the study was to evaluate postnatal changes in left ventricular (LV) contractility in very low birth weight (VLBW) infants. An echocardiographic study comparing 18 VLBW infants without significant complications and 16 normal term infants was carried out at the Neonatal Intensive Care Unit in Akita University Medical Hospital, Japan. The echocardiographic examinations were performed within 6 hours of birth and on day 5. We obtained the relations between rate-corrected mean velocity of circumferential fiber shortening (mVcfc) and end-systolic wall stress (ESS), which were calculated from two-dimensional LV short-axis views to compensate for the distorted LV shape, and we compared these relations statistically. In both VLBW and term infants there were inverse linear correlations between mVcfc and ESS for each study period (p < 0.05). The regression line of VLBW infants had a lower y-intercept and a steeper slope than that of term infants at 6 hours of age but almost corresponded on day 5. It is concluded that the left ventricle of VLBW infants adapts to postnatal hemodynamic alterations with low contractility but operates with a contractile state similar to that of term infants on day 5.     

Usefulness of Pulsed Wave Tissue Doppler Imaging in Assessment of Left Ventricular Functions in Children with Beta-Thalassemia Major

Objective

To evaluate the changes in the LV systolic and diastolic function in children with beta-thalassemia major (β-TM) using pulsed wave tissue doppler (TD) echocardiography.

Methods

Clinical, conventional echo doppler and pulsed wave tissue doppler imaging parameters were compared in 40 beta-thalassemia major patients (mean age, 6.52?±?3.5 y) and 25 age and sex matched normal subjects (mean age, 6.5?±?2.7 y).

Results

There were no significant statistical differences between mean fractional shortening (FS) and ejection fraction (EF) of left ventricle (LV) of the patients and control group. Children with beta-thalassemia had significantly lower E′ wave velocities measured at the left ventricular septal annulus (8.1?±?3.3 vs. 13?±?2.5, P?<?0.001), lateral margin of the mitral annulus (9.1?±?5.4 vs. 13.3?±?2.5, P?<?0.001) and lateral margin of the tricuspid annulus (9.3?±?3.9 vs. 13.3?±?2.5, P?<?0.001) when compared to the control group. Furthermore children with beta-thalassemia had significantly lower E′/A′ wave ratio at the left ventricular septal annulus (0.76?±?0.34 vs. 1.36?±?0.23), lateral margin of the mitral annulus (0.83?±?0.17 vs. 1.28?±?0.22), and lateral margin of the tricuspid annulus ((0.90?±?0.27 vs. 1.26?±?0.23, (P?<?0.05) when compared to the control group.

Conclusions

This study showed that patients with beta-thalassemia major and normal conventional echo doppler parameters had statistically significant changes detected by pulsed wave tissue doppler imaging.     

Noninvasive Measurement of Cardiac Output in Critically Ill Children

This study was performed to evaluate the hemodynamic status of children admitted to the intensive care unit, using suprasternal and transesophageal Doppler ultrasound, and to establish a suitable noninvasive technique to monitor trends in cardiac output in critically ill children. Twenty children were studied over a period of 6 months. The median age was 32.5 months and weight 14.5 kg. Minute distance (MD), which is a linear cardiac output parameter, was assessed. Seven simultaneous pairs of measurements of MD were made using transesophageal Doppler (TED) and suprasternal Doppler (SSD) by the same operator. Following a fluid challenge, seven repeat pairs of measurements were made. The mean percentage changes for MD by TED and SSD were 21.84 (SD 9.97) and 5.75 (SD 7.32). The average coefficients of variation for measurements of MD by TED and SSD were 2.34% and 15.98%, respectively. The mean difference in percentage change between MD, measured by TED and SSD, was 27.59 with a 95% confidence interval and wide limits of agreement. The repeatability of TED measurements was good, but the measurements by SSD were wide and erratic with poor reproducibility. Our study shows that TED is easy to use, reliable, and very useful for monitoring hemodynamic changes in critically ill children.     

Supplemental Nitrogen Inhalation Therapy in Very Low-Birth-Weight Infants with Patent Ductus Arteriosus

Very low-birth weight infants with patent ductus arteriosus (PDA) accompanied by severe heart failure do not respond to indomethacine therapy. It is essential to stabilize the general condition of these infants until surgical intervention. We tried to regulate the pulmonary blood flow to control congestive heart failure by administering supplemental nitrogen inhalation therapy to six very low-birth-weight infants with PDA. After the inhalation of supplemental nitrogen gas was begun, the arterial oxygen saturation and partial oxygen pressure immediately decreased. Furthermore, the blood pH, systolic pressure, and urine output significantly increased. The infants were well stabilized. Furthermore, there were no complications related to nitrogen gas inhalation. Supplemental nitrogen inhalation therapy is an effective and feasible therapy for severe congestive heart failure in very low-birth-weight infants with PDA.     

心输出量测定在危重患儿中的应用进展

心输出量(CO)是反映心脏功能的重要参数之一,对危重患儿准确监测CO及相关的血流动力学指标,对于指导临床治疗显得相当重要。监测CO有很多种方法,有创性的方法包括插入肺动脉漂浮导管的热稀释法及Fick定律法;无创性方法包括经食管多普勒法、经气管插管多普勒法、部分二氧化碳重复吸收法、胸阻抗法及超声心排量监测仪等方法。理想的CO监测法应具有无创、准确、重复性高、操作方便、价格便宜等特点。     

Hemodynamic Effects of Dexmedetomidine in Critically Ill Neonates and Infants With Heart Disease

The primary objective of this study was to evaluate the hemodynamic effects of dexmedetomidine (DEX) infusion on critically ill neonates and infants with congenital heart disease (CHD). The secondary objective of the study was to evaluate the safety and efficacy profile of the drug in this patient population. A retrospective observational study was conducted in the cardiovascular intensive care unit (CVICU) of a single tertiary care university children's hospital. The charts of all neonates and infants who received DEX in the authors' pediatric CVICU between August 2009 and June 2010 were retrospectively reviewed. The demographic data collected included age, weight, sex, diagnosis, and Risk Adjustment in Congenital Heart Surgery (RACHS-1) score. To evaluate the hemodynamic effects of DEX, physiologic data were collected including heart rate, mean arterial pressure (MAP), inotrope score, near-infrared spectroscopy, and central venous pressure (CVP). To assess the efficacy of DEX, the amount and duration of concomitant sedation and analgesic infusions over a period of 24?h were examined together with the number of rescue boluses. The potential side effects evaluated in this study included nausea, vomiting, abdominal distension, dysrhythmias, neurologic abnormalities, seizures, and signs and symptoms of withdrawal. During the study period, 50 neonates and infants received DEX for a median period of 78?h (range, 40-290?h). These patients had an average age of 3.53?±?2.64?months and a weight of 4.85?±?1.67?kg. Whereas 34 patients (68%) received DEX after surgery for CHD, 15 patients (30%) received DEX after heart transplantation. Of these 50 infants, 10 (20%) had a single-ventricle anatomy, whereas 13 (26%) had a risk adjustment score (RACHS-1) in the category of 4-6. The median CVICU stay was 29?days (range, 8-69?days). Despite a significant decrease in heart rate, MAP, inotrope score, and CVP, all the patients remained hemodynamically stable during DEX infusion. There was no substantial difference in major hemodynamic variables between neonates and infants, single- and two-ventricle repair, RACHS 4-6 and RACHS 1-3 categories for patients undergoing surgery, or patients undergoing heart transplantation and patients undergoing other surgical procedures. Dexmedetomidine infusion for neonates and infants with heart disease is safe from a hemodynamic standpoint and can reduce the concomitant dosing of opioid and benzodiazepine agents. Furthermore, DEX infusion may be useful for reducing vasopressor agent dosing in children with catecholamine-refractory cardiogenic shock.     

Estimation of Stroke Volume Using Doppler Echocardiography and Left Ventricular Echocardiographic Dimensions in Infants and Children

ABSTRACT. To evaluate the accuracy of noninvasive determination of stroke volume in infants and children, 28 patients (age range 4 weeks to 19 years) were studied. Stroke volume was calculated according to Teichholtz from M-mode echocardiographic tracings of left ventricular dimensions in 8 subjects. Agreement with thermodilution performed within 60 min of echocardiography was good ( r =0.995, y =0.91 x +1.59, SEE=1.8 ml). Since stroke volume correlated to body size we corrected for (height)³. After this correction there was still good agreement to thennodilution ( r =0.88, y =1.29 x -7.13, SEE=7.1 ml/H³). M-mode echocardiography was then used as a reference method for evaluating two ditrerent Doppler methods in the remaining 20 subjects. Continuous wave Doppler stroke distance, calculated from the mean velocity, was combined with aortic root area (Method I), and stroke dstance calculated from maximum velocity was combined with the aortic interleaflet area (Method II). Good agreement was found with Method I ( r =0.95, y =l.01 x -0.14, SEE=8.1 ml) and Method II ( r =0.95, y =1.04 x -1.14, SEE=8.4 ml). However, when stroke volume was normalized for (height)³, Method I was found to be superior to Method II.     

Relation between Blood Pressure, Left Ventricular Mass and Pulsed Doppler Parameters in Healthy School Children

We analyzed the relations between blood pressure in sitting and supine positions, left ventricular mass (LVM) and Doppler aortic, pulmonary and mitral flow velocity measurements in 163 healthy school children. Systolic blood pressure in a supine position correlated significantly with aortic acceleration (ATc) and ejection time)ETc), corrected by the square of R-R interval, pulmonary AT and peak flow velocities. Moreover, the systolic blood pressure in a sitting position correlated with pulmonary AT and LVM. LMV correlated with pulmonary ATc, the ratio of AT to ET andaverage acceleration, and aortic ETc and peak flow velocity. These data suggest the following: (1) the posture influences the relation between blood pressure and flow velocity, (2) pulmonary hemodynamics are influenced by systemic blood pressure in healthy children and (3) the development of LVM may be dependentnot only on blood pressure but also on cardiac work in childhood.     

组织多普勒评价轻症病毒性心肌炎患儿左心室舒张功能

目的比较脉冲多普勒与组织多普勒对轻症病毒性心肌炎(VM)患儿左室舒张功能检测的价值。方法应用组织多普勒测量轻症VM患儿60例二尖瓣环侧壁处舒张早期和晚期运动峰值速度(Ea、Aa),计算Ea/Aa值;应用脉冲多普勒测量其二尖瓣口血流E、A峰流速(E、A)和E/A;并与40例正常儿童对照。结果组织多普勒显示患病组Ea峰值流速减低、Aa峰值流速增高、Ea/Aa值减低;脉冲多普勒显示E峰峰值流速减低、A峰峰值流速增高、E/A值减低。患病组28例Ea/Aa<1(47%),10例E/A<1(17%),组织多普勒评价轻症VM患儿左室舒张功能(u=3.53 P<0.01)。结论VM患儿早期即可出现左室舒张功能减退,组织多普勒评价左室舒张功能较脉冲多普勒更敏感、准确。     

Postnatal Changes in Left Ventricular Volume and Contractility in Healthy Term Infants

To evaluate how the size of the ductus arteriosus affects neonatal left ventricular (LV) volume and contractility, we serially obtained two-dimensional and Doppler echocardiograms at 2, 12, 24, and 120 hours after birth in 20 healthy infants. LV volume was calculated by the biplanar Simpson's rule, and ductus arteriosus size with left-to-right shunting was measured by two-dimensional and Doppler echocardiography. At 2 hours, the ductus arteriosus was at its maximal size, and the LV end-diastolic volume was 1.2-fold higher than at the subsequent hours after birth. Additionally, there was a significant linear correlation between the end-diastolic volume and the ductal diameter. In contrast, the peripheral vascular resistance, derived from blood pressure measurements and Doppler echocardiography, was lowest at 2 hours of age. The mean normalized systolic ejection rate, an index of contractility, remained constant throughout the study period. These results suggest that alterations in the LV end-diastolic volume soon after birth depend on changes in ductal flow, which in turn is affected by ductal diameter, and that the neonatal left ventricle operates at its maximal performance with limited contractility during ductal patency.     

Outcomes of Hypoplastic Left Heart Syndrome in Low-Birth-Weight Patients

The objective of this study was to assess outcomes of hypoplastic left heart syndrome (HLHS) patients weighing ≤2.5 kg throughout staged palliation. We performed a single-center retrospective review. Abstracted data included gestational age, birth weight, presence of noncardiac anomalies, and survival through Fontan. Fifty-two patients met inclusion criteria, with a median birth weight of 2.14 kg and gestational age of 36 weeks. Five patients received comfort care only. Of 47 patients who underwent initial surgical palliation, 51% survived to initial hospital discharge. Birth weight and gestational age (GA) were similar between survivors and nonsurvivors. Compared with survivors, risk factors for death prior to initial hospital discharge were as follows: small for GA (P = 0.005), noncardiac anomalies (P = 0.04), need for post-perative extracorporeal membrane oxygenation (P = 0.0004), and conversion from initial palliation to Sano shunt (n = 5, no survivors). Operative survival following Stage 2 palliation was 91% (21/23) and 94% after Fontan (17/18). Overall survival for palliated patients from birth through Fontan was 36%. Low-birth-weight neonates with HLHS have poor overall survival through the Fontan operation, with highest mortality following Stage 1 palliation. Being small for GA and the presence of noncardiac anomalies are important preoperative risk factors for early mortality.     

Serial Plasma BNP Levels in Assessing Inadequate Left Ventricular Decompression on ECMO

We describe a female infant with complex single ventricle physiology who had undergone median sternotomy for placement of a right-sided systemic-to-pulmonary artery shunt, division of a patent ductus arteriosus, and left pulmonary artery augmentation. Her early postoperative course was complicated by cardiac arrest requiring institution of extracorporeal membrane oxygenation (ECMO) support. The brain natriuretic peptide (BNP) levels acutely improved after left ventricular decompression by insertion of a left atrial cannula. In this setting BNP levels may be an indicator of left ventricular stretch and are potentially a useful index to monitor left ventricular distension.     

Early versus Late Trophic Feeding in Very Low Birth Weight Preterm Infants

Objective

Improved survival of preterm infants, beneficial effects of trophic feeding and limited data on timing management of enteral feeding for very low birth weight preterm infants requires more researches to determine the exact starting time and increased volumes. This study aims to compare early (<48 h) versus late (>72h) trophic feeding with respect to important neonatal outcomes.

Methods

In a cohort study from September 2007 to October 2008, a total of 170 preterm infants (1000-1500 gram, 26-31 weeks) consisting of 125 who received trophic feeding enterally within the first 48 hours of birth (early group) and 45 fed enterally after 72 h0urs (late group), without major congenital birth defects and severe asphyxia entered the study. Bolus feeding was started in both groups at 1-2 cc/kg every 4-6 hours of human milk or preterm infant formula and was advanced 1-2 cc/kg/day if tolerated along with parenteral nutrition. Feeding intolerance, possibility of necrotizing entrocolitis (NEC), episodes of sepsis, body weight, length of NICU stay, and duration of parenteral nutrition were assessed serially.

Findings

There were no statistically significant differences in the clinical and maternal characteristics of infants in the two groups. The time to gain birth weight (13.75±5.21 vs 20.53±6.31 (P < 0.001)), duration of parenteral nutrition (9.26±4.572 days vs 14.11±6.415 days (P < 0.001)), hospital stay (12.14±8.612 vs 21.11±1.156 (P < 0.001)) were significantly shorter in early compared to late feeding group; none of the two groups experienced a high incidence of late onset sepsis (P = 0.73). There was 1 case of confirmed NEC in every group.

Conclusion

The benefits of early trophic feeding shown by this study strongly support its use for the preterm infants without adding to complications.     

Early Intravenous Indomethacin Prolongs Respiratory Support in Very Low Birth Weight Infants

ABSTRACT. Infants weighing 1500 g at birth requiring either intermittent positive pressure ventilation or continuous positive airway pressure by 12 hours of age were entered in a randomized double blind controlled trial to test the efficacy of early intravenous indomethacin therapy in preventing chronic pulmonary disease of prematurity. Of the 30 newborns enrolled, 15 were treated with indomethacin and 15 were treated with placebo at 12, 24 and 36 hours of age. The groups were similar for birth weight, gestational age, sex, hyaline membrane disease and intracranial hemorrhage. Infants in the placebo group were successfully weaned from intermittent positive pressure ventilation at an earlier age than infants in the indomethacin group ( p <0.05). Furthermore, chronic pulmonary disease of prematurity was similar in the two groups despite a reduction in the incidence of patent ductus arteriosus in the indomethacin group.     

Correlation Between Right Ventricular Tei Index by Tissue Doppler Imaging and Pulsed Doppler Imaging in Fetuses

The aim was to compare the right ventricular (RV) Tei index obtained by the tissue Doppler imaging (TDI) method with that obtained by the pulsed Doppler method in 29 fetuses aged 24-39 weeks (29.9 +/- 4.0 weeks). From pulsed Doppler recordings, the tricuspid closing-to-opening time (a) and RV ejection time (b) were measured. The Tei index determined by the pulsed Doppler method was calculated as (a - b)/b. From TDI recordings, the time interval during diastole (a') and the duration of the systole S-wave (b') were measured. The modified Tei index obtained by TDI was calculated as (a' - b')/b'. The time a' correlated strongly with a (r = 0.90, p < 0.0001). The mean difference between a' and a was 0.3 +/- 5.0 ms. There was also a strong correlation between b' and b (r = 0.94, p < 0.0001). The mean difference between b' and b was 0.5 +/- 3.3 ms. The TDI-Tei index correlated with the pulsed Doppler-Tei index (r = 0.83, p < 0.0001). The mean difference between the TDI-Tei index and the pulsed Doppler-Tei index was -0.003 +/- 0.04. This study demonstrated that the TDI-Tei index correlates well with the Tei index determined by pulsed Doppler in fetuses, suggesting that the TDI-Tei index is a feasible approach to assess global RV function in fetuses.