Reference values and calculation of z-scores of echocardiographic measurements of the normal pediatric right ventricle

Determination of right ventricular (RV) size and function has gained more interest in recent years in adults and children, especially in patients with congenital heart disease. Data on normal RV size parameters in children are scant. The aim of this study was to investigate growth-related changes in RV internal dimensions in a healthy pediatric cohort and the predictive value of RV parameters in identifying enlarged right ventricles in children with secundum-type atrial septal defects (ASD). A prospective study was conducted in a group of 576 healthy children (aged 1 day to 18 years) and 37 children (aged 1.4 to 17.7 years) with moderate-sized to large ASDs. The effects of age, body length, body weight, and body surface area were determined on the following RV parameters: end-diastolic basal diameter, end-diastolic midcavity diameter, end-diastolic length, end-systolic length, end-diastolic area, and end-systolic area. The predictive value of normal values stratified for age, body weight, body length, and body surface area was tested in children with ASDs. RV end-diastolic basal diameter, end-diastolic midcavity diameter, end-diastolic length, end-systolic length, end-diastolic area, and end-systolic area showed positive correlations with age, body length, body surface area, and body weight. In this population, RV z scores showed high specificity for detecting patients with ASDs, with sensitivity up to 89%, especially in children <8 years of age. In conclusion, the normal ranges of pediatric RV internal dimensions are provided. The z scores of these RV parameters were also calculated. Normal RV z scores might be important predictors in identifying enlarged right ventricles in patients with ASDs.

Virtually same oxidizability of LDL but higher Lp(a) levels in arterial compared to venous plasma

Plaque formation is confined to the arterial trunk. We assumed that due to the higher aeration of arterial compared to venous blood, higher levels of the atherogenic agent oxidized LDL might be present in arteries, contributing to plaque formation. We aimed to compare (i) the basal oxidative status of LDL in arterial and venous blood and (ii) the susceptibility of arterial and venous LDL to oxidation. The basal oxidative status of LDL was determined by measuring lipid hydroperoxide (LPO) concentrations, plasma levels of auto-antibodies against oxidized LDL, and by measuring oxidation-specific epitopes on LDL particles. The oxidizability of arterial vs. venous LDL (catalyzed by copper) was estimated by monitoring the time-course of conjugated dienes formation. Interestingly, we found the same basal oxidative status of LDL in arterial and venous plasma. LPO concentrations and levels of auto-antibodies against oxidized LDL were similar in arterial and venous plasma and amounts of oxidation-specific epitopes were similar on the respective LDL particles. Moreover, we found similar susceptibilities of arterial and venous LDL to (copper-mediated) oxidation. Lag-times until the onset of conjugated diene formation were slightly shorter in arterial compared to venous LDL in the presence of 5 μM, but not in the presence of 1 μM CuCl2. Additionally, we found significantly higher levels of the atherogenic lipoprotein(a) in arterial plasma. We conclude that not higher oxidizability of arterial LDL but higher arterial lipoprotein(a) levels might help to explain why sclerosis is confined to the arterial trunk.

In vitro oxidation of LDL by ozone

Recent studies suggest that ozone is present in atherosclerotic lesions. Since these lesions are characterized by a dramatic accumulation of low-density lipoprotein (LDL), we aimed to investigate whether ozone is capable of oxidizing LDL, thereby rendering this lipoprotein atherogenic. Lipid hydroperoxide (LPO) concentrations and thiobarbituric acid reactive substances (TBARS) were measured to assess the oxidative status of the lipid part of LDL. Relative electrophoretic mobility (REM) and oxidation-specific immune epitopes were measured to assess the oxidative status of the protein part (apoB) of the LDL particle. Ozone turned out to be a potent oxidant of LDL. LPO concentrations, TBARS, REM, and oxidation-specific immune epitopes significantly increased upon ozonization. Our results suggest that ozonization of LDL may be a novel pathway which supports atherogenesis. Ozone is capable of oxidizing the lipid part of LDL, followed by immediate oxidation of the protein part of LDL, rendering the lipoprotein atherogenic.

Reference values of the mitral annular peak systolic velocity (Sm) in 690 healthy pediatric patients, calculation of Z-score values, and comparison to the mitral annular Plane systolic excursion (MAPSE)

BACKGROUND

The mitral annular peak systolic velocity (Sm) is an echocardiographic measurement using tissue Doppler imaging to assess longitudinal left ventricular (LV) systolic function in children and adults. We determined growth-related changes in Sm to establish reference values for the entire pediatric age group.

METHODS AND RESULTS

A prospective study was conducted in a group of 690 healthy pediatric patients (age: 1 day-18 years). We determined the effects of age, sex, and body surface area (BSA) on the Sm values. Regression analysis was used to estimate Sm from age, BSA, and sex. In addition, a correlation of normal Sm with normal age-matched values of the M-mode parameter mitral annular plane systolic excursion (MAPSE) was measured. The Sm ranged from a mean of 5.8 cm/sec (Z-score ±2: 3.6-8.0 cm/sec) in the newborn to 11.8 cm/sec (Z-score ±2: 8.5-15.1 cm/sec) in the 18-year-old adolescent. The Sm values showed a positive correlation with age and BSA with a nonlinear course. There was no significant difference in Sm values between females and males. A significant correlation was found between Sm and MAPSE values.

CONCLUSION

Z-scores of Sm values were calculated and percentile charts were established to serve as reference data in patients with congenital heart diseases.

Supplementation with a juice powder concentrate and exercise decrease oxidation and inflammation, and improve the microcirculation in obese women: randomised controlled trial data

Obesity and sedentary lifestyle are associated with increased oxidative stress, inflammation and vessel dysfunction. Previous research has shown that an encapsulated fruit/berry/vegetable juice powder (FBV) supplement or controlled exercise training improve the markers of redox biology, low-grade inflammation and circulation. The aim of the present study was to assess the effects of 8 weeks of supplementation with FBV or placebo, and a single bout of controlled walking on the markers of oxidation, inflammation and skin capillary microcirculation in forty-two obese pre-menopausal women (41 (SD 5) years, non-smokers and BMI 34·5 (SD 3·8) kg/m(2)) using a randomised, double-blind, placebo-controlled design. All assessments were made before and after 8 weeks of capsule supplementation, and pre- and post-30 min of controlled treadmill walking at 70 % of VO2max. Venous blood was collected for the determination of carbonyl proteins (CP), oxidised LDL (ox-LDL), total oxidation status (TOS) of lipids, malondialdehyde, TNF-α and IL-6. Capillary blood flow, O2 saturation of Hb (SO2Hb) and the relative concentration of Hb (rHb) were assessed at a 2 mm skin depth. Following 8 weeks of supplementation, compared with placebo, the FBV group had a significant (P< 0·05) reduction in CP, ox-LDL, TOS and TNF-α, and a significant increase in blood flow, SO2Hb and rHb. Independent of supplementation, moderate exercise significantly increased blood flow and rHb, with a trend towards increased SO2Hb. Compared with placebo, 8 weeks of supplementation with FBV decreased the markers of systemic oxidation and inflammation. Both FBV supplementation and a single walking bout improved the markers of the microcirculation in these obese women.

Effects of a single bout of walking exercise on blood coagulation parameters in obese women

Obesity is associated with increased prevalence of thromboembolic events. We aimed to investigate whether obese women might benefit from vigorous aerobic exercise. Forty-two overweight and obese women performed a 30-min walking exercise test (treadmill ergometer) at an intensity of 70% of individual peak oxygen uptake. Blood samples were collected before and immediately after exercise. Thrombelastometry and platelet function measurements were performed on whole blood. Standard coagulation times, thrombin generation curves, markers of thrombin generation, fibrinolytic parameters, plasma levels of pro- and anticoagulatory factors, and microparticle procoagulant activity were determined in platelet-poor plasma samples. Thrombelastometry revealed a significant prolongation of clot formation time ( P = 0.037) and a significant deceleration of fibrin build up (alpha angle, P = 0.034) after exercise. Calibrated automated thrombography revealed a significant exercise-induced decrease in endogenous thrombin potential ( P = 0.039). Moreover, thrombin formation stopped earlier postexercise, reflected in shortened StartTail ( P = 0.046). Significantly elevated tissue-plasminogen activator levels ( P = 0.001) indicate an exercise-induced activation of the fibrinolytic system. White blood cell count increased significantly from pre- to postexercise ( P = 0.045), indicating a mild exercise-induced leukocytosis. The results of this study demonstrate that vigorous aerobic exercise might be a suitable tool to protect obese women from thrombotic events. We show that a single bout of vigorous aerobic exercise is clearly associated with an activation of the fibrinolytic system and a decreased readiness of the postexercise samples to form a clot and to generate thrombin, the pivotal enzyme of hemostasis.

Right ventricular performance in preterm and term neonates: reference values of the tricuspid annular peak systolic velocity measured by tissue Doppler imaging

BACKGROUND

The tricuspid annular peak systolic velocity (S') is an echocardiographic measurement to assess systolic right ventricular function in adults and children.

OBJECTIVE

We determined growth and birth weight-related changes of S' to establish reference values in preterm and term neonates.

METHODS

A prospective study was conducted in a group of 290 preterm and term neonates (gestational age 26 + 0 to 40 + 6 weeks of gestation; birth weight 660-4,460 g). A correlation of S' values with established tricuspid annular plane systolic excursion (TAPSE) values was performed.

RESULTS

The S' ranged from a mean of 4.5 cm/s (Z-score ± 2 SD: 3.6-5.5 cm/s) in preterm neonates in week 26(0-6) of gestation to 7.8 cm/s (Z-score ± 2 SD: 5.5-10.1 cm/s) in term neonates in week 40(0-6) of gestation. The S' values increased from 26 to 40 weeks of gestation. S' and week of gestation are strongly correlated: Pearson's correlation coefficient was 0.66 for week of gestation - S' (p < 0.001). A significant correlation was found between S' and TAPSE values (r = 0.67; p < 0.001).

CONCLUSION

Z-scores of S' values were calculated and percentile charts were established to serve as reference data for preterm and term neonates with structurally normal hearts.

Coagulation changes during presyncope and recovery

Orthostatic stress activates the coagulation system. The extent of coagulation activation with full orthostatic load leading to presyncope is unknown. We examined in 7 healthy males whether presyncope, using a combination of head up tilt (HUT) and lower body negative pressure (LBNP), leads to coagulation changes as well as in the return to baseline during recovery. Coagulation responses (whole blood thrombelastometry, whole blood platelet aggregation, endogenous thrombin potential, markers of endothelial activation and thrombin generation), blood cell counts and plasma mass density (for volume changes) were measured before, during, and 20 min after the orthostatic stress. Maximum orthostatic load led to a 25% plasma volume loss. Blood cell counts, prothrombin levels, thrombin peak, endogenous thrombin potential, and tissue factor pathway inhibitor levels increased during the protocol, commensurable with hemoconcentration. The markers of endothelial activation (tissue factor, tissue plasminogen activator), and thrombin generation (F1+2, prothrombin fragments 1 and 2, and TAT, thrombin-antithrombin complex) increased to an extent far beyond the hemoconcentration effect. During recovery, the markers of endothelial activation returned to initial supine values, but F1+2 and TAT remained elevated, suggestive of increased coagulability. Our findings of increased coagulability at 20 min of recovery from presyncope may have greater clinical significance than short-term procoagulant changes observed during standing. While our experiments were conducted in healthy subjects, the observed hypercoagulability during graded orthostatic challenge, at presyncope and in recovery may be an important risk factor particularly for patients already at high risk for thromboembolic events (e.g. those with coronary heart disease, atherosclerosis or hypertensives).

Tricuspid annular peak systolic velocity (S') in children and young adults with pulmonary artery hypertension secondary to congenital heart diseases, and in those with repaired tetralogy of Fallot: echocardiography and MRI data

BACKGROUND

Tricuspid annular peak systolic velocity (S'), as an echocardiographic index to assess right ventricular (RV) systolic function, has not been investigated thoroughly in children and young adults with repaired tetralogy of Fallot (TOF) and pulmonary artery hypertension secondary to congenital heart disease (PAH-CHD).

METHODS

S' values in patients with TOF (n = 183) and PAH-CHD (n = 55) were compared with those in normal subjects. S' values were compared with RV ejection fraction and RV end-diastolic volume index (RVEDVi) determined by magnetic resonance imaging.

RESULTS

S' values became significantly reduced in PAH-CHD patients after 10.4 years of age and after 13.6 years of age in patients with TOF compared with the lower boundary of the ±2-SD interval of normal subjects. Significant positive correlations between S' and RV ejection fraction were seen in patients with TOF (r = 0.66, P < .001) and those with PAH-CHD (r = 0.82, P < .001). Significant negative correlations between S' and RVEDVi were also seen in patients with repaired TOF (r = -0.29, P = .002) and in those with PAH-CHD (r = -0.59, P < .001).

CONCLUSIONS

Although initially preserved, in this prospective study, impaired S' values with increasing age were found in patients with repaired TOF and PAH-CHD. Persistent pressure overload in patients with PAH-CHD as well as volume overload in those with repaired TOF might lead to systolic RV functional impairment and increased RVEDVi. The validity of S' data was supported by magnetic resonance imaging data (RVEDVi and RV ejection fraction).

Systolic right ventricular function in children and young adults with pulmonary artery hypertension secondary to congenital heart disease and tetralogy of Fallot: tricuspid annular plane systolic excursion (TAPSE) and magnetic resonance imaging data

OBJECTIVE

  The tricuspid annular plane systolic excursion (TAPSE), as echocardiographic index to assess right ventricular (RV) systolic function, has not been investigated thoroughly in children and young adults with tetralogy of Fallot (TOF) and pulmonary artery hypertension secondary to congenital heart disease (PAH-CHD).

PATIENTS

  TAPSE values of 49 patients with PAH-CHD and 156 patients with TOF were compared with age-matched normal subjects. TAPSE values were also compared with RV ejection fraction (RVEF) and RV indexed end-diastolic volume (RVEDVi) determined by magnetic resonance imaging in PAH-CHD and TOF patients.

RESULTS

  Patients with a PAH-CHD showed a positive correlation between TAPSE with RVEF (r= 0.81; P < 0.001) and a negative correlation between TAPSE with RVEDVi (r=-0.67; P < 0.001). Similarly, in our TOF patients, a positive correlation between TAPSE with RVEF (r= 0.65; P < 0.001) and a negative correlation between TAPSE with RVEDVi (r=-0.42; P < 0.001) was seen.

CONCLUSIONS

  Significant pressure overload in PAH-CHD patients and volume overload in TOF patients lead to a decreased systolic RV function, determined by TAPSE and magnetic resonance imaging and to increased RVEDVi values, determined by MRI, with time.

Systolic right ventricular function in preterm and term neonates: reference values of the tricuspid annular plane systolic excursion (TAPSE) in 258 patients and calculation of Z-score values

BACKGROUND

The tricuspid annular plane systolic excursion (TAPSE) is an echocardiographic measurement to assess right ventricular systolic function in adults and children.

OBJECTIVE

We determined growth- and birth weight-related changes of TAPSE to establish reference values in preterm and term neonates.

METHODS

A prospective study was conducted in a group of 258 preterm and term neonates (age: 25+0 to 40+6 weeks of gestation, birth weight: 530-4200 g).

RESULTS

The TAPSE ranged from a mean of 0.44 cm (Z-score ±2: 0.30-0.59 cm) in preterm neonates in the 26th week of gestation to 1.03 cm (Z-score ±2: 0.85-1.21 cm) in term neonates in the 41st week of gestation. The TAPSE values increased in a linear way from the 26th to 41st week of gestation. TAPSE, week of gestation and weight are strongly correlated: Pearson's correlation coefficient was 0.93 for week of gestation - TAPSE (p < 0.001), 0.93 for week of gestation - birth weight (p < 0.001), and 0.89 for birth weight - TAPSE (p < 0.001). There was no statistically significant difference of normal TAPSE values between female and male patients (p = 0.987).

CONCLUSION

Z-scores of TAPSE values were calculated and percentile charts were established to serve as reference data for ready application in preterm and term neonates with structurally normal hearts and with congenital heart disease in the future.

Effects of nadroparin, enoxaparin, and unfractionated heparin on endogenous formation of factor Xa and IIa and on thrombelastometry profiles in cord versus adult blood

BACKGROUND

To date, only few pharmacokinetic studies on low-molecular-weight heparins (LMWHs) in neonates exist not allowing to formally assess pharmacodynamics of LMWHs in neonates.

OBJECTIVE

To evaluate the anticoagulant effects of the two LMWHs nadroparin and enoxaparin on endogenous formation of FXa or FIIa in cord versus adult platelet-poor plasma (PPP) and on thrombelastometry profiles in cord versus adult whole blood (WB). Unfractionated heparin (UH) was the reference antithrombotic drug.

METHODS

The effects of nadroparin, enoxaparin, or UH on endogenous formation of FXa or FIIa was investigated in tissue factor-activated PPP using a subsampling technique and chromogenic substrates. The anticoagulant efficacy of these drugs was also investigated in WB triggered by the physiological relevant activator collagen/endogenous thrombin using thrombelastometry.

RESULTS

The major findings are (i) nadroparin is as efficient as enoxaparin concerning inhibition of the endogenous formation of FXa and FIIa, (ii) cord PPP and WB are significantly more susceptible to the addition of LMWHs or UH than adult PPP or WB, and (iii) compared by equivalent anti-FXa activity, the anticoagulant action of UH is markedly higher than that of the LMWHs in PPP and WB of neonatal or adult origin.

CONCLUSIONS

Administration of LMWHs in neonates has to be performed carefully to avoid bleeding side effects due to their high anticoagulant efficacy in cord PPP and WB.

Heparinase-modified thrombelastometry: inactivation of heparin in plasma samples

BACKGROUND

The heparinase-modified thrombelastometry (HEPTEM) assay is a promising tool to assess the coagulation status of heparinised patients. The aim of our study was to examine the heparin neutralizing capability of the HEPTEM assay in plasma samples.

METHODS

In the HEPTEM assay, blood or plasma samples become activated via the intrinsic pathway in the presence of a heparin processing enzyme.

RESULTS

We examined coagulation times (CTs) in the presence of increasing amounts (0-4 IU/mL) of heparin. We found that up to a concentration of 0.5 IU/mL, heparin is completely neutralized. However, CTs increased linearly in the presence of heparin concentrations higher than 0.5 IU/mL, indicating incomplete heparin neutralization in the standard HEPTEM assay.

CONCLUSIONS

We provide herein a mathematical procedure to correct the misleadingly prolonged CTs (for heparin > 0.5 IU/mL) for the HEPTEM assay performed in plasma samples to allow better estimation of the coagulation status in patients requiring intense anticoagulation (e.g., patients undergoing cardiac surgery).

Estimating DXA total body fat percentage by lipometer subcutaneous adipose tissue thicknesses

DXA is an accepted reference method to estimate body composition. However several difficulties in the applicability exist. The equipment is rather expensive, not portable, impractical for measurement of big study populations and it provides a minimal amount of ionizing radiation exposure. The optical device Lipometer (EU Pat.No. 0516251) provides non-invasive, quick, precise and safe measurements of subcutaneous adipose tissue (SAT) layer thicknesses at any site of the human body. Compared to DXA there are some advantages in the Lipometer approach, because this device is portable, quick, not expensive and no radiation is involved. To use these advantages in the field of total body fat% (TBF%) assessment, an acceptable estimation of DXA TBF% by Lipometer SAT thicknesses is necessary, which was the aim of this study. Height, weight, waist and hip circumferences, DXA TBF% and Lipometer SAT thicknesses at fifteen defined body sites were measured in 28 healthy men (age: 33.9 +/- 16.6 years) and 52 healthy women (age: 40.1 +/- 10.7 years). To estimate Lipometer TBF% stepwise multiple regression analysis was applied, using DXA TBF% as dependent variable. Using the fifteen Lipometer SAT thicknesses together with age, height, weight and BMI as independent variables provided the best estimations of Lipometer TBF% for both genders with strong correlations to DXA TBF% (R = 0.985 for males and R = 0.953 for females). The limits of agreement were -2.48% to +2.48% for males and -4.28% to + 4.28% for females. For both genders we received a bias of 0.00%. The results of this paper extend the abilities of the Lipometer by a precise estimation of TBF% using DXA as golden standard.

Collagen/endogenous thrombin-induced platelet aggregation in cord versus adult whole blood

BACKGROUND

In previous studies, neonatal platelets have been shown to be hypoaggregable to various agonists when compared with adult platelets.

OBJECTIVES

It was the aim of this study to investigate the aggregability of neonatal versus adult platelets when the physiological relevant agonist collagen/endogenous thrombin is used.

METHODS AND RESULTS

Whole blood (WB) aggregation experiments employing the impedance method revealed the same responsiveness of neonatal and adult platelets to collagen/endogenous thrombin. Maximum aggregation (13.5 +/- 3.2 vs. 13.6 +/- 3.2 Omega; p = 0.94), slope (5.8 +/- 1.8 vs. 6.2 +/- 2.6 Omega/min; p = 0.79) and lag time until the onset of platelet aggregation (38.7 +/- 8.9 vs. 42.6 +/- 16.5 s; p = 0.59) were similar in cord and adult WB. However, the rise in serotonin plasma levels due to platelet activation was significantly lower in neonates versus adults (227.57 +/- 57.65 vs. 473.34 +/- 155.75 ng/ml; p = 0.0001). Furthermore, we found a fast capability of cord plasma to generate (the efficient platelet agonist) endogenous thrombin: thrombin generation started significantly earlier in cord compared with adult plasma (215 +/- 19 vs. 247 +/- 21 s; p = 0.01). Moreover, thrombelastometry revealed significantly shorter coagulation times in cord versus adult WB activated with collagen/endogenous thrombin (229.8 +/- 12.5 vs. 256.3 +/- 25.3 s; p = 0.003).

CONCLUSIONS

The efficient platelet aggregation in cord WB provoked by collagen/endogenous thrombin might help to explain the clinically observed well-functioning primary hemostasis of neonates.

Thrombin generation in paediatric patients with congenital heart disease. Determination by calibrated automated thrombography

Thrombin generation was studied in paediatric patients with congenital heart disease (CHD) undergoing cardiac surgery using the calibrated automated thrombography (CAT) in terms of the lag time until the onset of thrombin formation, time to thrombin peak maximum (TTP), endogenous thrombin potential (ETP), and thrombin peak height. The suitability to determine the coagulation status of these patients was investigated.

PATIENTS, MATERIAL, METHODS

CAT data of 40 patients with CHD (age range from newborn to 18 years) were compared to data using standard coagulation parameters such as prothrombin (FII), antithrombin (AT), tissue factor pathway inhibitor (TFPI), prothrombin fragment 1.2 (F 1.2), thrombin-antithrombin (TAT), activated partial thromboplastin time (aPTT), and prothrombin time (PT).

RESULTS

A significant positive correlation was seen between ETP and FII (p < 0.01; r = 0.369), as well as between peak height and FII (p < 0.01; r = 0.483). A significant negative correlation was seen between ETP and TFPI values (p < 0.05; r = -0.225) while no significant correlation was seen between peak height and TFPI. A significant negative correlation was seen between F 1.2 generation and ETP (p < 0.05; r = -0.254) and between F 1.2 generation and peak height (p < 0.05; r = -0.236). No correlation was seen between AT and ETP or peak.

CONCLUSIONS

CAT is a good global test reflecting procoagulatory and inhibitory factors of the haemostatic system in paediatric patients with CHD.

Clot strength: a comparison between cord and adult blood by means of thrombelastometry

OBJECTIVE

To evaluate the clot strength in cord versus adult blood.

METHOD

Thrombelastometry (TEM) was the method of choice as it provides information on the clot strength in terms of the maximum clot firmness (MCF) and on the fibrin polymerization process in terms of the clot formation time and the alpha angle.

RESULTS

The MCFs were significantly lower in cord versus adult platelet rich plasma (PRP, 63.0+/-3.8 vs. 67.0+/-3.9 mm, P=0.006) and in cord versus adult whole blood (WB, 55.3+/-3.8 vs. 59.3+/-3.6 mm, P=0.001) employing the thrombelastometry with extrinsic activator assay. We suggest that the diminished clot strength in cord versus adult blood and plasma samples is attributable to an impaired polymerization of neonatal fibrin: (i) the thrombelastometry with extrinsic activator and inactivated platelets (FIBTEM) assay revealed significantly lower MCFs in cord versus adult PRP (23.0+/-3.1 mm vs. 27.3+/-3.9 mm, P=0.002) and in cord versus adult WB (11.6+/-2.3 mm vs. 15.3+/-3.3 mm, P<0.001); (ii) the alpha angle in the FIBTEM assay was significantly lower in cord versus adult WB (39.0+/-12.8 degrees vs. 55.5+/-12.3 degrees, P=0.02); (iii) the clot formation times in the FIBTEM assay were significantly longer in cord versus adult PRP (248.0+/-143.5 s vs. 81.5+/-39.8 s, P=0.001).

CONCLUSIONS

Neonatal fibrin shows impaired polymerization properties under our experimental conditions resulting in reduced clot strength compared with fibrin of adult origin.

Thrombin generation determined by calibrated automated thrombography (CAT) in pediatric patients with congenital heart disease

INTRODUCTION

Thrombin generation was studied in pediatric patients with congenital heart disease (CHD) undergoing cardiac surgery using the calibrated automated thrombography (CAT) in terms of the lag time until the onset of thrombin formation, time to thrombin peak maximum (TTP), endogenous thrombin potential (ETP), and thrombin peak height. The possible suitability to determine the coagulation status of these patients was investigated.

MATERIALS AND METHODS

CAT data of 40 patients with CHD (age range from newborn to 18 years) were compared to data using standard coagulation parameters such as prothrombin (FII), antithrombin (AT), tissue factor pathway inhibitor (TFPI), prothrombin fragment 1.2 (F 1.2), thrombin-antithrombin (TAT), activated partial thromboplastin time (aPTT), and prothrombin time (PT).

RESULTS

A significant positive correlation was seen between ETP and FII (p<0.01; r=0.369), as well as between peak height and F II (p<0.01; r=0.483). A significant negative correlation was seen between ETP and TFPI values (p<0.05; r=-0.225) while no significant correlation was seen between peak height and TFPI. A significant negative correlation was seen between F 1.2 generation and ETP (p<0.05; r=-0.254) and between F 1.2 generation and peak height (p<0.05; r=-0.236). No correlation was seen between AT and ETP or peak.

CONCLUSIONS

Our data indicate that CAT is a good global test reflecting procoagulatory and inhibitory factors of the hemostatic system in pediatric patients with CHD.

Collagen/endogenous thrombin-induced platelet aggregation in whole blood samples

The aim of the study was to investigate the individual and combined effects of collagen (3.5 microg/ml) and endogenously generated thrombin (due to addition of 0.35 pmol/l tissue factor) on platelet aggregation in the physiological environment of whole blood by means of the impedance method. Lag times were significantly shorter when a combination of collagen and endogenous thrombin was used to provoke platelet aggregation (41.9 +/- 16.3 s) compared with collagen (173.8 +/- 52.1 s, P < 0.0001) or endogenous thrombin (94.3 +/- 43.6 s, P < 0.001). Amplitudes and slopes were the lowest in collagen-induced experiments (2.83 +/- 1.59 Omega and 1.79 +/- 0.45 Omega/min, respectively), whereas they were approximately the same in endogenous thrombin-induced experiments whether collagen was present or not (13.7 +/- 3.1 versus 11.2 +/- 4.0 Omega and 6.3 +/- 2.8 versus 5.6 +/- 2.3 Omega/min, respectively). No synergistic effect of collagen and endogenous thrombin on the clot formation process was observed by means of thrombelastometry. Moreover, thrombin potentials in tissue factor-activated plasma samples were approximately the same whether collagen was present or not (834 +/- 67 versus 809 +/- 63 nmol/l.min). In conclusion, endogenously generated thrombin is a potent platelet agonist in whole blood, and a combination of collagen and endogenous thrombin synergistically shortens the lag time until the onset of platelet aggregation.

Myocardial infarction in an adolescent: anomalous origin of the left main coronary artery from the right coronary sinus in association with combined prothrombotic defects

We present the case of a 15-year-old boy with clinical features of an acute myocardial infarction. Angiography revealed a complete obstruction of the left main coronary artery. A coronary-aorto-bypass graft was undertaken immediately. Cardiac computed tomography demonstrated an anomalous origin of the left main coronary artery from the right coronary sinus of the aorta. A thrombophilic state with a heterozygote genotype for prothrombin G20210 mutation, a C677T methylenetetrahydrofolate reductase gene mutation, and a protein C type 1 deficiency was detected. No other embolic source could be identified. The patient recovered with persistent left ventricular dysfunction. He is now taking the anticoagulant warfarin. Combined prothrombotic defects in combination with additional risk factors such as coronary anomalies can lead to myocardial infarction even in children and adolescents.