Management and follow-up of arterial thrombosis in the neonatal period

Symptomatic aortic thrombosis in a preterm neonate

Symptomatic aortic thrombosis is a devastating condition in the neonatal intensive care unit (NICU), which is now increasingly being diagnosed with the availability of bedside ultrasound. Early intervention can go a long way towards preventing adverse outcomes. In our case, a preterm, very low birth weight, growth-restricted baby developed aortic thrombosis with hypertensive emergency and later limb-threatening ischaemia, which usually requires thrombolysis. However, due to the parents' reservations, he was given only therapeutic anticoagulation (with closely monitored activated partial thromboplastin time targets), which resulted in complete thrombus resolution. A multidisciplinary team approach was followed, and early detection with frequent monitoring led us to a favourable outcome.

Acute neonatal arterial occlusion: is thrombolysis safe and effective?

PURPOSE

We report our experience of the management of arterial occlusion in the newborn.

METHODS

A case note review was carried out after ethical approval. Doppler ultrasonography confirmed the occlusion. Thrombolysis was the primary intervention. Surgery was used selectively. A good outcome was one without tissue loss or functional impairment or minimal tissue loss without functional impairment. Data are presented as medians with ranges.

RESULTS

Ten patients (9 male; median gestational age, 35.5 weeks [range, 28-39 weeks]) presented on day 1 (range, 1-8 days). Initial management included systemic tissue plasminogen activator (8 patients) and surgery (2 infants in whom thrombolysis was contraindicated). Improvement was noted in 7 of 8 infants treated medically and in both who underwent surgery. Three infants had significant tissue loss. Outcome at 29 months (range, 1.3-95.4 months) was good in the remaining 7.

CONCLUSIONS

A multidisciplinary approach, thrombolysis and selective surgery achieved tissue preservation and function in the majority while minimizing complications. Early referral to centers with multidisciplinary teams is recommended.

Thrombolytic agents for arterial and venous thromboses in neonates

BACKGROUND

Clinically symptomatic thromboses are infrequent but serious complications in infants undergoing intensive care. Most are related to central vascular catheters. Symptomatic thrombosis may cause severe morbidity due to irreversible organ damage and also loss of limbs.

OBJECTIVES

To assess the efficacy and safety of thrombolytic agents in neonatal arterial and venous thromboses.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 2, 2004), MEDLINE (January 1966 to January 2004), EMBASE (January 1980 to January 2004), and CINAHL (January 1982 to January 2004). We also contacted authors of appropriate review articles.

SELECTION CRITERIA

Randomised controlled trials (RCT) and quasi RCT comparing thrombolytic agents with either heparin or observation in neonates with symptomatic neonatal arterial and venous thromboses were included.

DATA COLLECTION AND ANALYSIS

Two reviewers independently searched for eligible trials. No eligible studies were found even after contacting authors of review articles for details of any unpublished trials.

MAIN RESULTS

No randomised controlled trials (RCT) or quasi-RCT were found.

AUTHORS' CONCLUSIONS

No conclusions could be made as no eligible studies were found. It is time that a randomised controlled trial was performed comparing thrombolytic therapy to heparin therapy to aid neonatologists in the treatment of arterial and venous thromboses.

Neonatal thrombosis and its treatment

Thromboembolic disease (TE) has been described as the new epidemic of tertiary paediatrics, and no where is this more evident than in the neonatal population. As survival of premature and sick newborns has improved, the frequency of complications associated with intensive supportive therapy and monitoring has increased. Clinically significant thrombosis is emerging as one of the more common complications associated with improved neonatal outcome. The long-term implications of neonatal thrombosis are only just being realised. This systematic review will consider the epidemiology, diagnostic strategies, and outcome for both arterial and venous TE in neonates. The role of inherited thrombophilic abnormalities, and the evidence for anticoagulation therapy will also be considered. The lack of high level evidence in determining optimum therapy is obvious. Further research regarding diagnostic strategies, and optimal therapies is urgently needed.

Acute renal failure in the newborn

Acute renal failure in the newborn is a common problem and is typically classified as prerenal, intrinsic renal disease including vascular insults, and obstructive uropathy. In the newborn, renal failure may have a prenatal onset in congenital diseases such as renal dysplasia with or without obstructive uropathy and in genetic diseases such as autosomal recessive polycystic kidney disease. Acute renal failure in the newborn is also commonly acquired in the postnatal period because of hypoxic ischemic injury and toxic insults. Nephrotoxic acute renal failure in newborns is usually associated with aminoglycoside antibiotics and nonsteroidal anti-inflammatory medications used to close a patent ductus arteriosis. Alterations in renal function occur in approximately 40% of premature newborns who have received indomethacin and such alterations are usually reversible. Renal artery thrombosis and renal vein thrombosis will result in renal failure if bilateral or if either occurs in a solitary kidney. Cortical necrosis is associated with hypoxic/ischemic insults due to perinatal anoxia, placenta abruption and twin-twin or twin-maternal transfusions with resultant activation of the coagulation cascade. As in older children, hospital acquired acute renal failure is newborns is frequently multifactorial in origin. Although the precise incidence and prevalence of acute renal failure in the newborn is unknown, several studies have shown that acute renal failure is common in the neonatal intensive care unit. Recent interesting studies have demonstrated that some newborns may have genetic risks factors for acute renal failure. Once intrinsic renal failure has become established, management of the metabolic complications of acute renal failure continues to involve appropriate management of fluid balance, electrolyte status, acid-base balance, nutrition and the initiation of renal replacement therapy when appropriate. Renal replacement therapy may be provided by peritoneal dialysis, intermittent hemodialysis, or hemofiltration with or without a dialysis circuit. The preferential use of hemofiltration by pediatric nephrologists is increasing while the use of peritoneal dialysis is decreasing except for neonates and small infants. Peritoneal dialysis has been a major modality of therapy for acute renal failure in the neonate when vascular access may be difficult to maintain. In the newborn, the prognosis and recovery from acute renal failure is highly dependent upon the underlying etiology of the acute renal failure. Factors that are associated with mortality include multiorgan failure, hypotension, need for pressors, hemodynamic instability, and need for mechanical ventilation and dialysis. The mortality and morbidity of newborns with acute renal failure is much worse in neonates with multiorgan failure. Newborns who have suffered substantial loss of nephrons as may occur in cortical necrosis are at risk for late development of renal failure after apparent recovery from the initial insult. Similarly, hypoxic/ischemic and nephrotoxic injury to the developing kidney can result is decreased nephron number. Newborns with acute renal failure need life-long monitoring of their renal function, blood pressure, and urinalysis. Typically, the late development of chronic renal failure will first becomes apparent with the development of hypertension, proteinuria, and eventually an elevated blood urea nitrogen and creatinine.

Neonatal thrombosis

Neonatal thrombosis is a serious event that can cause mortality or result in severe morbidity and disability. The most important risk factor for the development of thrombosis during the neonatal period is the presence of an indwelling central line and consequently the vessels involved tend to be those most frequently used for catheterization. Other documented risk factors for the development of neonatal thrombosis include asphyxia, septicemia, dehydration, maternal diabetes and cardiac disease. Main laboratory findings for the diagnosis of hypercoagulable states, include shortened aPTT, decreased levels of inhibitors (AT III, Protein C and Protein S), increased resistance to activated protein C, defective fibrinolysis (basal and after stimuli), increased levels of clotting factors (fibrinogen, factor VII, factor VIII, etc.), increased and/or hyperactive platelets, increased whole blood and/or plasma viscosity, Antiphospholipid antibodies and presence of prothrombotic molecular defects like FV Leiden, P20210 and MTHFR. Approximately 4% and 2% respectively of Caucasians are heterozygous for these gene defects. Their causative role in neonatal thrombosis is unknown but they may have a contributory role in the pathogenesis of thrombosis in neonates.

Thromboembolic disease and antithrombotic therapy in newborns

This update uses an evidence based approach to analyze and present the epidemiology of neonatal thrombosis, etiologies, currently used techniques for diagnosis with their limitations, and current therapeutic approaches. In addition, the approaches to both prevention and optimal therapies are discussed. In Section I Dr. Paul Monagle addresses the epidemiology of neonatal thrombosis outside of the central nervous system in both arterial and venous locations, and those that occur in utero. The specific contributions of catheters and congenital prothrombotic disorders are delineated. Dr. Monagle also describes currently used techniques for the diagnosis of thrombotic events as well as their limitations and the current therapeutic approaches. In Section II, Dr. Gabrielle deVeber reviews the epidemiology of neonatal thrombosis within the central nervous system, in both arterial and venous locations and those that occur in utero. The neurological presentation, risk factors including congenital prothrombotic disorders, anatomical distribution, diagnostic tests, use of antithrombotic therapy and neurologic outcome of neonates with either sinovenous thrombosis or arterial ischemic stroke are discussed. In Section III, Dr. Anthony Chan reviews the current approaches to the prevention and treatment of neonatal thrombosis. Information on the differences in the response of neonates compared to adults to antithrombotic therapy and new approaches to the prevention and treatment of thrombosis in neonates are emphasized.

Renal follow up of premature infants with and without perinatal indomethacin exposure

AIMS

To evaluate early childhood renal growth, structure, and function in children born at less than 33 weeks gestation and to investigate possible independent effects of perinatal indomethacin exposure.

METHODS

A total of 66 children born at less than 33 weeks gestation, 31 of them with perinatal indomethacin exposure (study group) and 35 without (control group), were examined at 2-4 years of age. Serum cystatin C and protein; plasma creatinine, sodium, and potassium; urine protein, calcium:creatinine ratios, and alpha(1) microglobulin; and glomerular filtration rate (GFR) were determined. Renal sonography examinations were performed.

RESULTS

The mean serum cystatin C concentrations were slightly higher in the control group than in the study group. Mean values of serum protein, and plasma creatinine and sodium did not differ between the groups, neither did median plasma potassium concentrations and urine protein:creatinine and calcium:creatinine ratios. None had tubular proteinuria. Abnormal GFR (<89 ml/min/1.73 m(2)) was found in one case in each group and renal structural abnormalities in five in each group. In logistic regression analysis the duration of umbilical artery catheter (UAC) use and furosemide treatment emerged as the significant independent risk factors for renal structural abnormalities. Furosemide treatment and assisted ventilation remained the risk factors associated with renal abnormalities in general-that is, functional and/or structural abnormal findings.

CONCLUSION

Perinatal indomethacin does not seem to affect long term renal growth, structure, or function in children born at less than 33 weeks gestation. Duration of UAC use, furosemide treatment, and assisted ventilation may be correlated with later renal structural and functional abnormalities.

Transumbilical balloon angioplasty of subclavian artery thrombosis in a neonate

We present a case of arterial thrombosis of the upper extremity in a 1-day-old neonate. The initial response to thrombolytic and anticoagulant therapy alone was unsuccessful. Distal flow to the extremity was reestablished by combined percutaneous transluminal angioplasty of the subclavian artery using transumbilical access followed by resumption of the thrombolytic and anticoagulant regimen. Cathet. Cardiovasc. Intervent. 49:56-60, 2000.

Echocardiographic diagnosis of thrombus originating from the ductus arteriosus

Initial functional closure of the ductus arteriosus normally occurs within hours after birth, with permanent closure taking several weeks. The mechanism for ductal closure has been well studied and has not been shown to include thrombus formation. We describe a normal infant found to have a thrombus originating in the ductus arteriosus that occluded the ductus and subsequently extended into the left pulmonary artery, threatening to occlude it as well. This case illustrates the importance of echocardiography in making this rare diagnosis. It also emphasizes the role of echocardiography as an effective means of following the progression or regression of such a thrombus.

Iatrogenic vascular lesions in extremely low birth weight and low birth weight neonates

PURPOSE

Aggressive treatment has improved the long-term outcome of extremely low birth weight (ELBW) and low birth weight (LBW) neonates, but it has also increased the risk of iatrogenic lesions. The aim of this paper is to evaluate the incidence of vascular injuries observed in the neonatal intensive care unit of our hospital.

METHODS

From 1987 to 1994, 2898 neonates were admitted to the neonatal intensive care unit; 335 of them were either LBW or ELBW (11.5%). A review of the charts of these neonates disclosed nine neonates (four male, five female) with vascular lesions (2.6%); the mean gestational age of these patients was 28.7 weeks (range, 24 to 33 weeks), the mean weight at birth was 880 g (range, 590 to 1450 g), and the mean weight at diagnosis was 1825 g (range, 1230 to 2700 g). In the same period, 10 neonates with vascular injuries were reported in the 2563 neonates who weighed more than 1500 g (0.3%). The injuries observed in LBW and ELBW group were arteriovenous fistulas (two bilateral) at the femoral level (six neonates), carotid lesion (one neonate), and limb ischemia (two neonates). Injury was associated with venipuncture in seven neonates, and with umbilical catheter in one; the case of carotid lesion was related to surgical error. No general symptoms were observed.

RESULTS

The carotid lesion and five arteriovenous fistulas were repaired by microsurgical techniques; one case of limb ischemia was resolved with thrombolytic drugs, whereas an amputation at the knee level was required in the other after 10 days of medical treatment. One neonate with an arteriovenous fistula was just observed according to the parents' wishes. At clinical and echo-color Doppler follow-up, seven of nine neonates had normal vascular function without sequelae.

CONCLUSIONS

In our experience, LBW and ELBW neonates are at greater risk than older neonates of the development of iatrogenic vascular lesions. We advocate aggressive microsurgery, medical treatment, or both to obtain good results and prevent late sequelae.

Perinatal limb ischemia: orthopaedic implications

Fifteen patients (16 ischemic limbs) who ultimately required amputation for perinatal limb ischemia were treated at The Children's Hospital of Philadelphia and the Shriners Hospital for Crippled Children in Philadelphia between 1980 and 1993. The average birth weight of these patients was 1,870 g, and the average gestational age was 30.8 weeks. Ischemic events occurred at an average postnatal age of 5.4 weeks. The causes of the ischemia included (a) arterial thrombosis as a complication of arterial catheterization (eight patients), (b) thromboembolism resulting from a hypercoagulable state (five patients), (c) intravenous infiltrate (one patient), and (d) in utero arterial thrombosis (one patient). Amputation was required at an average postnatal age of 8.5 weeks. The final patient, with concurrent ischemia involving the right hand and left leg, had complete resolution of the ischemic hand with fibrinolytic therapy alone and required only an amputation of the lower extremity. Eleven of the 15 patients were available for follow-up (two dead, two lost to follow-up), at an average of 4.5 years. Nine of these 11 patients (six lower and three upper extremities) are functioning well in prostheses. The two remaining patients are infants who will be fitted for lower-extremity prostheses when they begin to attempt to walk.

Renal blood flow velocity in neonates with and without umbilical artery catheters

We performed an observational prospective cohort study on the applicability of two-dimensional echocardiography with pulsed Doppler technique as a noninvasive modality to serially evaluate renal blood velocities in premature neonates with and without umbilical artery catheters. We also sought to determine the incidence of umbilical artery catheter-related thrombus formation in our neonatal intensive-care unit. We established normative values for renal artery blood flow velocities in premature neonates and postulate that this echo-Doppler technique is valid and can be used to evaluate renal developmental physiology in the neonatal population. In addition, we observed that even in the absence of clinical sequelae due to thrombus formation, the presence of a thrombus in the aorta caused abnormalities in renal hemodynamics.

Imaging of neonatal arterial thrombosis

The case of a neonate who presented with symptoms of upper limb ischemia related to spontaneous multiple arterial and venous thromboses that were demonstrated by colour Doppler sonography and digital subtracted angiography is reported. The presentation of limb ischaemia at birth may be the warning sign of simultaneous cerebral infarction.

Renovascular hypertension: a rare cause of neonatal salt loss

We report a case of severe hypertension in the newborn period due to obstruction of the right renal artery. The baby presented with polyuria leading to dehydration and was found to have hyponatraemia and severe renal salt loss. When sudden malignant hypertension is induced in experimental conditions, a high pressure diuresis and increased angiotensin II production are found. These findings could explain the renal salt loss, notwithstanding the effects of secondary hyperaldosteronism and hyper-reninaemia.