Prediction of Postoperative Left Ventricular Pump Function in Congenital Mitral Regurgitation

In adult patients with severe chronic mitral regurgitation, many predictors for estimating postoperative left ventricular systolic function have been proposed. However, none has been defined in children. We analyzed the relationship between such predictors and postoperative left ventricular fractional shortening in children with isolated congenital mitral regurgitation. Eight patients with isolated congenital mitral regurgitation were examined before and after surgery with echocardiography. Fractional shortening, left ventricular end-diastolic and end-systolic dimension indices, and left ventricular end-systolic wall stress/left ventricular end-systolic dimension index in the preoperative status were poorly correlated with postoperative left ventricular fractional shortening. Predictive wall stress, which was calculated from preoperative data of end-diastolic dimension, end-diastolic wall thickness, and diastolic blood pressure, correlated well with postoperative left ventricular fractional shortening (r=−0.90, p= 0.0024). It is important to consider not only myocardial contractility but also postoperative afterload for estimating postoperative left ventricular performance in chronic severe mitral regurgitation.     

Reduced left ventricular afterload and increased contractility in children with insulin-dependent diabetes mellitus: An M-mode and Doppler-echocardiographic evaluation of left ventricular diastolic and systolic function

Summary Twenty-three children with diabetes mellitus, their ages ranging from 0.2–9.8 years, but with no sign of diabetic microvascular disease were investigated by M-mode and Doppler echocardiography, along with a comparable group of control subjects. In the diabetics, the fractional shortening and the mean velocity of fractional shortening were 14 and 18% higher, respectively, whereas the left ventricular end-systolic wall stress, an indicator of left ventricular afterload, was markedly reduced (22%). Assuming an unchanged preload in the two groups, this indicates a reduced afterload in these children. Systolic and diastolic time intervals, heart rate, and blood pressure were similar in diabetics and controls. Doppler-derived transmitral left ventricular filling indices were also similar. Thus, in these diabetic children no signs of left ventricle is considered to be due to a reduced afterload in early insulin-dependent diabetes.     

Changes in cardiac function during extracorporeal membrane oxygenation for persistent pulmonary hypertension in the newborn infant

The effects of extracorporeal membrane oxygenation (ECMO) on cardiac function and its determinants (preload, afterload, contractility, and heart rate) are largely unknown, although some evidence exists that function may decrease. To determine whether cardiac function decreases and what changes in the determinants take place during and after ECMO, we observed 26 newborn infants with persistent pulmonary hypertension. Serial echocardiograms were performed before ECMO, during maximum cardiopulmonary bypass, and after ECMO. Cardiac function was assessed by using standard echographic ejection phase indices (shortening fraction and cardiac output). Heart rate, preload (left ventricular end-diastolic dimension and area), afterload (left ventricular end-systolic wall stress), and contractility (relationship between velocity of circumferential fiber shortening and wall stress) were also measured. Ejection phase indices significantly decreased during ECMO (shortening fraction 33% to 25%, cardiac output 205 to 113 ml/kg/min; p less than 0.05) and returned to normal after ECMO (shortening fraction 26% to 34%, cardiac output 107 to 240 ml/kg/per minute; p less than 0.05). Heart rate also significantly decreased during ECMO (158 to 118 beats/min; p less than 0.05). Preload significantly increased after ECMO (left ventricular end-diastolic dimension 1.4 to 1.6 cm, left ventricular end-diastolic area 1.9 to 2.2 cm2; p less than 0.05). There were no significant changes in contractility and afterload during any study period. We conclude that, although left ventricular ejection phase indices and heart rate decreased during ECMO, these changes were transient and resolved when bypass was terminated. Contractility and afterload did not appear affected by bypass.     

Effects of low-dose dobutamine on left ventricular diastolic filling in children

To investigate the effects of dobutamine on the Doppler transmitral flow pattern in children with normal left ventricular function, Doppler echocardiography was used to measure the transmitral flow in 14 healthy children before and during infusion of dobutamine (5 μg/kg per minute). Cardiac output was measured by the thermodilution method, and stroke volume was calculated as the cardiac output divided by the heart rate. Dobutamine increased the peak velocity and flow velocity–time integral of early diastolic filling without changing those of atrial contraction and normalized peak velocity of early diastolic filling, suggesting an increase in left ventricular relaxation. Dobutamine increased the stroke volume and rate-corrected mean velocity of fiber shortening with reduced end-systolic wall stress, indicating an increase in left ventricular contractility. The percentage of increase in the flow velocity–time integral of early diastolic filling during dobutamine infusion tended to correlate with the increase in stroke volume (r= 0.67, p < 0.05) and with the decrease in end-systolic wall stress (r=−0.61, p < 0.05). Our results suggest that low-dose dobutamine increases left ventricular relaxation with enhanced systolic function. The observed decreased end-systolic wall stress might have caused enhanced relaxation characteristics with dobutamine.     

Left ventricular performance in neonates on extracorporeal membrane oxygenation

Summary The evaluation of left ventricular systolic performance in infants undergoing extracorporeal membrane oxygenation (ECMO) using traditional ejection-phase indices is hampered by significant alterations in preload and afterload. Therefore, a load-independent index, which relates heart-rate-corrected mean velocity of circumferential fiber shortening (VCFc) to afterload, measured as end-systolic wall stress (ESS), was used to assess left ventricular function in 18 term neonates undergoing ECMO. The mean age at the onset of ECMO was 75.5 h and the duration of therapy was 171±106 h. Left ventricular performance was highest before the onset of ECMO (VCFc=1.65±0.49 circ/s) and decreased toward normal during (1.38±0.33 circ/s) and following ECMO (1.29±0.16 circ/s). Initially, nine of 17 (53%) patients had enhanced performance for the degree of afterload but in only 16 of 48 (33%) studies during ECMO and none following ECMO was VCFc elevated beyond the normal range predicted for ESS. These changes in left ventricular performance may be the result of variations in exogenous, as well as endogenous, catecholamines rather than intrinsic alterations in myocardial contractility. It is concluded that the VCFc/ESS relation permits a meaningful assessment of ventricular performance in critically ill neonates undergoing ECMO.     

Cardiovascular effects of a phosphodiesterase III inhibitor, amrinone, in infants: Non-invasive echocardiographic evaluation

OBJECTIVE: The inotropic effect of amrinone is still controversial in management of congestive heart failure in pediatric patients, especially in infants. In order to determine the cardiovascular effect of amrinone in pediatric patients, we performed echocardiographic evaluation in 11 infants (mean age of 2 months) after intracardiac surgery. METHODS: Amrinone was loaded with a dose of 1.0 mg/kg, followed by continuous infusion with 10 microg/kg per min. We performed echocardiographic measurements before and immediately after loading of amrinone, and evaluated its cardiovascular effect. RESULTS: After loading of amrinone, the heart rate increased by 5% in average, but there was no change in blood pressure. Left ventricular (LV) fractional shortening and mean velocity of circumferential fiber shortening corrected for heart rate increased significantly (0.25 +/- 0.09 to 0.28 +/- 0.08 and 0.94 +/- 0.35 to 1.10 +/- 0.34, respectively). Left ventricular end-systolic wall stress decreased from 36.6 +/- 18.5 to 29.1 +/- 14.4 g/cm2, indicating the reduction of LV afterload. Stress-velocity index, a sensitive index of left ventricular contractility, was elevated significantly (Z-score: -1.45 +/- 4.21 to 0.04 +/- 4.11). CONCLUSION: Amrinone has not only vasodilative effects, but definite positive inotropic effects in infants with heart failure.     

Immediate and short-term effects of pulmonary artery banding on left ventricular performance in foetal sheep

AIM: To evaluate foetal left ventricular performance when its preload was increased by banding the pulmonary artery, a study design where a simultaneous change in left ventricular afterload is unlikely. METHODS: Nine ovine foetuses were studied with real-time images and Doppler echocardiography before, 3-4 and 6-8 d after surgery. Seven of these foetuses were also studied during the surgical intervention, immediately before and within 2 min after banding. RESULTS: The immediate effects of a 90-95% reduction of the pulmonary artery cross-sectional area were: a 53 +/- 20% (mean +/- SD) decrease and a 38 +/- 10% increase of right (RvQ) and left ventricular output (LvQ), respectively. Comparing measurements before and 3-4 d after operation, there was a 64 +/- 16% decrease of RvQ and a 64 +/- 25% increase of LvQ. The increase in LvQ was due to an increase in both heart rate (19 +/- 10%) and stroke volume (38 +/- 18%). After an additional 3-4 postoperative days, heart rate remained increased to the same extent, but there was a more pronounced increase of LvQ (93 +/- 19%) and stroke volume (59 +/- 22%). CONCLUSION: The parallel foetal circulation has a capacity to handle a severely increased afterload for the right ventricle by immediately improving and maintaining an increased left ventricular performance. This improvement was in part accomplished by an increase in stroke volume.     

Serial echocardiographic and Doppler evaluation of left ventricular systolic performance and diastolic filling in premature infants

To examine the effects of somatic growth on left ventricular systolic and diastolic functions in premature infants, we performed serial two-dimensional, M-mode and Doppler echocardiograms of 18 premature infants in the early neonatal period (mean of 14 days) and on the day when they were discharged from the hospital (mean of 94 days). The relation between rate-corrected mean velocity of fiber shortening and end-systolic wall stress relation was used as a load-independent estimate of contractility. Diastolic function was assessed by transmitral Doppler filling velocity patterns. The end-systolic wall stress was significantly lower in the first examination than in the second examination (38+/-8 vs. 46+/-10 g/cm2, P < 0.005). However, there was no significant difference in the rate-corrected velocity of fiber shortening between the two examinations. An inverse linear relation between the end-systolic wall stress and the rate-corrected mean velocity of fiber shortening was found in each examination. The slopes of these two regression lines showed no significant difference, suggesting that the left ventricular contractility is on the same level during this study period. The transmitral Doppler flow velocity patterns markedly altered between the two observations. The peak E wave, peak A wave, peak E/A ratio, flow velocity time integral of E/A wave, the first third filling fraction, and the normalized peak filling rate to stroke volume increased significantly during the study period (78+/-14 vs. 31+/-9 cm/s, 61+/-12 vs. 33+/-7 cm/s, 1.29+/-0.18 vs. 0.93+/-0.19, 1.75+/-0.58 vs. 1.17+/-0.24, 0.42+/-0.07 vs. 0.37+/-0.05, and 9.48+/-1.71 vs. 7.30+/-0.96/s, respectively, P < 0.001), suggesting a relative shift of Doppler filling into the early diastole. We demonstrated that the age- and growth-related alterations in the transmitral Doppler filling patterns occurred dramatically without changes in contractility during the first 3 months after birth. This diastolic filling change may be related to the age-related maturation in the left ventricular diastolic properties.     

Right ventricular performance and pulmonary haemodynamics in adolescent and adult patients with cystic fibrosis

A combined haemodynamic and radionuclide approach was used to evaluate right ventricular performance in 16 adolescent and adult patients with cystic fibrosis (CF). There were nine patients with mild arterial hypoxaemia (PaO₂>80% of predicted) and normal resting pulmonary artery pressure and seven patients with severe arterial hypoxaemia (PaO₂<70% of predicted) and resting pulmonary arterial hypertension (PH). The right ventricular ejection fraction (RVEF) by equilibrium angiocardiography using krypton 81^m as a tracer and stroke volume index (SVI) by thermodilution techniques were measured simultaneously and right ventricular end-diastolic and end-systolic volumes were derived. RVEF was normal in CF patients without PH (58.9±7.2%) but was reduced in those with PH (45.4±2.6%). There was a statistically significant inverse linear correlation between RVEF and afterload as assessed by mean pulmonary artery pressure and pulmonary vascular resistance (PVR: r=–0.78), indicating that RVEF ist afterload-dependent. Right ventricular function, however, as assessed by right ventricular end-systolic pressure-volume relations was even higher in CF patients with PH, indicating preserved or even increased right ventricular function in the face of an increased afterload stress.Abbreviations CF cystic fibrosis - PaO₂ arterial oxygen tension - PH pulmonary arterial hypertension - RVEF right ventricular ejection fraction - SVI stroke volume index - Pap pulmonary artery pressure - PVR pulmonary vascular resistance - COPD chronic obstructive pulmonary disease - VC vital capacity - FEV₁ forced expiratory volume in 1 s - RV resisdual volume - TLC total lung capicity - RVEDP right ventricular end-diastolic pressure - Pap_s systolic pulmonary artery pressure - Pap_d diastolic pulmonary artery pressure - PCWP pulmonary capillary wedge pressure - CO cardiac output - ED end-diastolic background-corrected counts - ES end-systolic background-corrected counts - CI cardiac index - RVEDVI right ventricular end-diastolic volume index - RVESVI right ventricular end-systolic volume index - P/V relation right ventricular end-systolic pressure/right ventricular end-systolic volume index - S-K score Shwachmann-Kulczycki score     

Left ventricular end-systolic wall stress to volume relationship before and after surgical closure of ventricular septal defect

Summary Left ventricular function was examined angiographically in 64 patients with ventricular septal defect and 13 postoperative patients with a preoperatively large shunt (postoperative group). The unoperated 64 patients were divided into three groups; small (left-to-right shunt ratio <35%), moderate (35%–50%), and large (>50%). The control group consisted of 27 patients with Kawasaki disease. For assessing left ventricular function, left ventricular shape and the end-systolic wall stress to end-systolic volume index ratio, as well as left ventricular ejection fraction were examined. Left ventricular ejection fraction was higher in the small-shunt group (p<0.05) than in the control group, but normal in the other groups. Left ventricular end-diastolic shape was normal only in the small-shunt group and more spherical in the other groups. The large-shunt group alone manifested more spherical left ventricular end-systolic shape and lower end-systolic wall stress to end-systolic volume index (p<0.001). These findings suggest that the left ventricular dysfunction is present in patients with a left-to-right shunt larger than 50%, but this change was reversible in patients who underwent early repair of ventricular septal defect.     

The late consequences of anthracycline treatment on left ventricular function after treatment for childhood cancer

The purpose of this study was to determine the incidence of changes in left ventricular function in patients in long-term remission after treatment with anthracyclines for a childhood malignancy. The authors examined 155 patients in disease remission who underwent treatment protocols utilising anthracyclines in childhood. The group comprised 90 males and 65 females aged 15±4.9 years (range 5–29 years, median 15 years). The age at the time of diagnosis and start of treatment was 8.6±4.9 years (range 1–18 years, median 8 years). The time of follow-up was 7.3±4 years (range 1–21 years, median 6.3 years). The patients were given a cumulative dose of doxorubicin or daunorubicin of 250±131 mg/m² (range 50–1200 mg/m², median 240 mg/m²). The values of ejection fraction below 55% and fractional shortening below 30% assessed by means of echocardiography were considered as pathological. The control group consisted of 41 volunteers. Pathological values of fractional shortening were found in 12 patients (8%). Only one patient (0.64%) showed the development of heart failure due to cardiomyopathy. The group of the patients after chemotherapy revealed significantly worse values of left ventricular endsystolic wall stress, mean velocity of circumferential fibre shortening, Tei index, and isovolumic relaxation period in comparison with the control group. We found a correlation between the given cumulative dose of anthracyclines and indicators of systolic function of the left ventricle, but not a relation to the time indicators (age at diagnosis, time of follow-up). Conclusion:in the mean period of 6 years after chemotherapy, subclinical cardiotoxicity was found in 11 patients (7%) and cardiomyopathy with heart failure in one patient. Further indicators of subclinical damage are elevation of afterload (end-systolic stress), impaired relaxation and increased value of the Doppler index of global left ventricular function. Further monitoring and evaluation of the relevant subclinical abnormalities over a longer period of time are needed.Abbreviations CD cumulative dose - DT deceleration time - E/A index of the diastolic filling of the left ventricle - EF ejection fraction - ESS end-systolic stress - FS fractional shortening - HR heart rate - IRT isovolumic relaxation time - LV left ventricle - LVPWDd end-diastolic diameter of the left ventricular posterior wall - LVPWex excursion of the left ventricular posterior wall - LVPWP percentage of the systolic thickening of the left ventricular posterior wall - MPI myocardial performance index - mVcf _c mean velocity of circumferential fibre shortening     

Systolic and diastolic function in children with chronic renal failure

BACKGROUND: Cardiovascular complications are the most frequent cause of death in patients with end-stage renal failure (ESRF). We aimed to investigate systolic and diastolic functions in children with ESRF. METHODS: Thirty-nine children with ESRF (17 on continuous ambulatory peritoneal dialysis (CAPD), eight on hemodialysis and 14 on predialysis) were examined to assess systolic and diastolic functions by echocardiography and ultrasound Doppler. Left ventricular systolic and diastolic functions were measured both in patients and age-matched healthy controls (n = 20) and the indices of cardiac performance were compared. RESULTS: Increased left ventricular mass index (LVMI) and decreased volume/mass ratio with normal systolic left ventricular function was found in patients, as compared with controls. Left ventricular diastolic dysfunction was observed in dialysis patients. In most of these patients, left ventricular isovolumic relaxation time was prolonged, except in CAPD patients. The peak of late diastolic flow (A) velocities were increased with a reduction of the early diastolic flow velocity (E)--the E/A ratio. The E velocities were unchanged in all patients as compared with controls. Our data indicated an abnormality of myocardial relaxation in patients with ESRF. We found no relationship between E/A ratio and LVMI. Among three groups of patients, the LVMI and diastolic abnormalities were highest in the hemodialysis group indicative of poor control of hypervolemia and hypertension. CONCLUSIONS: The technique of CAPD has some advantages as a renal replacement therapy for preserving cardiac functions as compared with hemodialysis. However, it must be remembered that patients with hemodialysis have features that effects cardiac status, such as higher volume load and higher afterload (hypertension).     

Assessment of right ventricular diastolic filling parameters by Doppler echocardiography

BACKGROUND: Right ventricular diastolic function has been evaluated in various diseases by the pulsed Doppler technique. Right ventricular diastolic filling parameters show changes with age, heart rate and respiration. Evidences of diastolic left and right ventricular dysfunctions have been reported by echocardiographic studies in asthmatic patients. In the present study, before and after treatment of asthma the right ventricular diastolic filling parameters were compared in children with moderate asthma by Doppler echocardiography (a non-invasive technique). METHODS: The study group consisted of 20 children (eight girls, 12 boys) with asthma. During the present study these patients were treated with inhaled steroid and beta-2 agonist daily. Before treatment all patients were evaluated by Doppler echocardiography. At 4-6 weeks after treatment 15 patients that had shown improvement in their symptoms according to the symptom score were also evaluated by Doppler echocardiography. RESULTS: The mean age was 8.6 +/- 2.69 years and mean period of symptoms were 56.4 +/- 35.8 months. When compared with results of echocardiography before and after treatment, the right ventricular diastolic filling parameters (acceleration time: P < 0.01, deceleration time: P < 0.01 and isovolumetric relaxation time: P < 0.05) were found to be significantly different. CONCLUSIONS: We observed significant improvement of right ventricular diastolic filling parameters by Doppler echocardiography after treatment in children with asthma.     

Functional Echocardiographic Assessment of Myocardial Performance in Anemic Premature Infants: A Pilot Study

This prospective observational study conducted in a neonatal intensive care unit aimed to evaluate echocardiographic changes provoked by anemia and transfusion of packed red blood cells (pRBCs) in premature infants. In this study, 32 anemic premature infants had serial echocardiographic assessment of left ventricular (LV) systolic performance, LV preload, and afterload immediately before, within 48 h, and up to 120 h after the transfusion of pRBCs. Pretransfusional evaluations also were compared with similar assessments of 71 nonanemic inpatient premature infants analogous for sex, gestational age at birth, and postnatal age. Left ventricular systolic performance was estimated from fractional shortening, LV output, and LV myocardial performance index (LVMPI). The LV preload was estimated from the LV end-diastolic dimension and the ratio of left atrium-to-aortic root dimension (LA/Ao ratio). The LV afterload was estimated from end-systolic wall stress. The LVMPI was found to decrease with increasing corrected gestational age in both the nonanemic (R = 0.173; p = 0.03) and anemic (R = 0.460; p = 0.007) infants. The LVMPI was the only index that changed after transfusion of pRBCs, decreasing in the younger anemic infants (p = 0.011) and increasing in the older anemic infants (p = 0.012). Finally, a significant inverse relationship between pre- and posttransfusional LVMPI values (R = 0.730; p < 0.001) was noted. The LVMPI may allow for identification of preterm infants more likely to be helped by transfusion of pRBCs.     

Left ventricular function in isolated rheumatic mitral stenosis in children

A total of 18 patients with pure rheumatic mitral stenosis between the ages of eight and 14 years (average 11.8 years) were studied. Left ventricular angiograms in the right anterior oblique view were obtained in each. Moderate to severe pulmonary arterial hypertension was present in all but one. The mean left ventricular end-systolic volume index was 25.4 +/- 8.5 ml/m2; it was increased in five patients. The mean left ventricular end-diastolic volume index was 64 +/- 13.5 ml/m2. It was normal in all except one patient, in whom it was increased to 91 ml/m2. The left ventricular stroke volume index, 39.6 +/- 8.8 ml/m2, was within the normal range. The left ventricular stroke volume index, 39.6 +/- 8.8 ml/m2, was within the normal range. The mean left ventricular ejection fraction was 0.61 +/- 0.09 ml, with a range of 0.44-0.72. The mean left ventricular ejection fraction was lower than normal (P less than 0.05). The ejection fraction was low in five of the 18 patients. Four of the five patients with an ejection fraction below 0.60 had severe pulmonary arterial hypertension. There was no correlation between the ejection fraction and left atrial pressure or the mitral valve area. Segmental contraction analysis in the five patients with a low ejection fraction showed global hypokinesia in four and segmental hypokinesia, involving predominantly the posterobasal segment, in one patient. Our study suggests that even children with pure mitral stenosis may have left ventricular dysfunction in the absence of active carditis.     

Echocardiographic evaluation of cardiac functions and left ventricular mass in children with malnutrition

OBJECTIVE: This study was undertaken to assess the left ventricular mass (LV Mass) and systolic and diastolic functions of the left ventricle in children with protein energy malnutrition (PEM). METHODOLOGY: Thirty children, aged between 2 months and 2 years with PEM (four kwashiorkor, seven marasmic- kwashiorkor, 19 marasmus), and 17 healthy, age-matched children, using Doppler echocardiography were studied. RESULTS: The mean LV Mass in the patients was lower than that in the controls (14.5 +/- 5.2 vs 19.8 +/- 4.7 g, P < 0.05). However, the LV Mass/body surface area was not different in the patients with PEM and in the control group (52 +/- 9.2 vs 53.9 +/- 8.2g/m(2), P > 0.05), indicating that LV Mass was reduced in proportion to decrease in body size in malnutrition. Left ventricular septal and posterior wall thickness in PEM were also lower than that in the controls, and the most significant reduction in the LV Mass, septal and posterior wall thickness were found in the kwashiorkor group. Cardiac output was reduced in proportion to decrease in body size in the patient group (1.6 +/- 0.5 vs 2.1 +/- 0.8 L/min, P < 0.05), therefore cardiac index was not significantly different between the patients and the control subjects (5.9 +/- 1.4 vs 5.7 +/- 1.6 L/min/m(2), P > 0.05). Systolic function indices including ejection fraction, fractional shortening, and diastolic function indices were not significantly different in the groups. CONCLUSIONS: We demonstrated that LV Mass and cardiac output were reduced in proportion to decrease in body size in patients with PEM, and LV systolic and diastolic functions were preserved in atrophic hearts.     

Cardiovascular effects of high-dose growth hormone treatment in growth hormone-deficient children

Growth hormone (GH) hypersecretion is associated with an increased incidence of cardiac hypertrophy and subclinical abnormalities of left ventricular (LV) function. The unlimited availability of biosynthetic GH has led to progressively increased dosage when treating GH-deficient children, raising the question of its cardiovascular effects during long-term therapy. We compared 22 children (8 girls, 14 boys), mean age 12.1 years (range 3–17 years) with GH deficiency who were receiving chronic GH treatment (GH group) with 22 normal controls matched for sex and body size in order to evaluate: (1) LV volume, mass, and systolic function by two-dimensional guided M-mode echocardiography; (2) LV diastolic function by pulsed-wave Doppler sampling of the transmitral flow; and (3) cardiac output and systemic vascular resistance by Doppler echocardiography. All patients had been on chronic GH therapy for 13.8±7.6 months (range 5–30 months) with an average dose of 0.95±0.12 IU/kg per week (range 0.69–1.17 IU/kg per week). Blood pressure did not differ between the two groups. LV volume, mass, ejection fraction, and mean velocity of circumferential shortening did not differ significantly between the GH group and controls; nor did the peak- and end-systolic meridional stress. All patients had a normal contractile state as estimated by the relation between mean velocity of circumferential shortening and end-systolic meridional stress. The LV filling parameters did not differ between the two groups, and there was no difference in cardiac index and systemic vascular resistance. These f9ndings suggest that long-term treatment with high doses of GH in GH-deficient children and adolescents does not lead to adverse cardiac effects. Whether longer-duration therapy could cause morphofunctional alterations of the left ventricle requires further investigation.     

Contractility Reserve in Children Undergoing Dialysis by Dobutamine Stress Echocardiography

Left ventricular hypertrophy is an adaptive mechanism in children undergoing chronic dialysis to improve contractility at rest. The aim of this study was to determine the left ventricular performance and contractility reserve by “dobutamine stress echocardiography” in children undergoing chronic dialysis. Thirty-five children undergoing dialysis and 24 healthy subjects were enrolled in this prospective study. We evaluated contractility by means of end-systolic wall stress—velocity of circumferential fiber shortening (VCFc) in 24 healthy subjects and 35 dialysis patients. Dobutamine stress echocardiography was obtained only in children undergoing dialysis. Patients were divided into two groups according to left ventricular mass index. Contractile reserve was estimated by the difference in contractility at rest versus during echocardiography. Significantly higher VCFc (p = 0.008) and VCFc (p = 0.002) differences at rest were observed in the patient group compared to healthy subjects. Children undergoing dialysis had a higher left ventricular mass index compared with controls (42.38 ± 12.41 vs. 17.57 ± 3.66 g/m^2.7, respectively; p = 0.001). Patients with left ventricular hypertrophy had a significantly lower contractile reserve compared with patients without left ventricular hypertrophy (p = 0.013). These findings suggest that children undergoing dialysis have increased left ventricular mass and contractility at rest. However, the contractile reserve during dobutamine stress echocardiography was reduced. Dobutamine stress echocardiography may identify children undergoing dialysis at risk of progressing to systolic dysfunction and heart failure.     

负荷多普勒超声技术评价川崎病患儿左心功能的临床研究

目的 探讨双嘧达莫负荷多普勒超声技术在川崎病患儿左心储备功能评价方面的临床应用价值.方法 选择超声检查均提示有冠状动脉增宽的川崎病患儿21例,根据99Tcm-甲氧基异丁基异腈心肌断层扫描检查结果 将患儿分为2组,核素分布稀疏组(A组)14例,核素分布正常组(N组)7例.分别于双嘧达莫负荷前后测量左室射血分数(LVEF)、心脏指数(CI)、射血前时间/左室射血时间(PEP/LVET)、短轴缩短率(FS)、二尖瓣环处舒张早期最大峰值流速(Emax)及舒张晚期最大峰值流速(Amax).结果 负荷试验前,A组与N组各项指标比较差异无显著性(P>0.05).负荷后,A组CI明显降低(P<0.05);PEP/LVET明显增高(P<0.05).负荷后1?h时,A组与N组CI和PEP/LVET恢复到负荷前水平.结论 心肌断层扫描核素分布异常的川崎病患儿左室收缩储备能力下降.双嘧达莫负荷超声心动图技术操作简便、安全,可连续性评价患儿的心功能,便于随访.     

Immune function in pure iron deficiency

Immunologic studies were performed in ten iron-deficient children, aged 12 to 30 months, before and after iron replacement. Chronic infection, malnutrition, and vitamin deficiency were excluded. Mean hemoglobin levels went from 8.2 +/- 0.2 (SEM) to 12.3 +/- 0.3 g/dL after iron replacement. Mean T-cell percentage increased from 50% +/- 3.0% to 58% +/- 3.7%. Absolute numbers of T cells were unchanged. Three children converted negative in vitro proliferative responses to Candida or tetanus antigen. Mean stimulation indexes increased for Candida (6.8 +/- 1.7 to 17.9 +/- 6.7) and tetanus (19.5 +/- 6.0 to 31.7 +/- 8.5). Nine of 16 delayed hypersensitivity skin tests were positive before and ten of ten were positive after iron therapy. The IgG and IgA levels did not change significantly, but IgM levels decreased from 181 +/- 13 to 128 +/- 5 mg/dL. We conclude that T-cell immunity is slightly impaired in pure iron deficiency and that these subtle defects can be corrected with oral iron replacement.