Pulmonary Embolism, Infarction, and Hemorrhage

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Chapter 401 Pulmonary Embolism, Infarction, and Hemorrhage

401.1 Pulmonary Embolus and Infarction

Venous thromboembolic disease (VTE) is well described in children and adolescents with or without risk factors (Table 401-1). Improvements in therapeutics for childhood illnesses and increased survival with chronic illness may contribute to the larger number of children presenting with thromboembolic events, which can be a significant source of morbidity and mortality.

Etiology

Commonly appreciated risk factors for thromboembolic disease in adults include immobility, malignancy, pregnancy, infection, and hypercoagulability; up to 20% of adults with this disorder may have no identifiable risk factor (see Table 401-1). Children with deep venous thrombosis (DVT) and pulmonary embolism (PE) are much more likely to have 1 or more identifiable conditions or circumstances placing them at risk. In a large Canadian registry, 96% of pediatric patients were found to have 1 risk factor and 90% had 2 or more risk factors.

Embolic disease has variable etiologies in children. An embolus can contain thrombus, air, amniotic fluid, septic material, or metastatic neoplastic tissue; thromboemboli are most commonly encountered. A commonly encountered risk factor for DVT and PE in the pediatric population is the presence of a central venous catheter. The presence of a catheter in a vessel lumen as well as instilled medications can induce endothelial damage and favor thrombus formation.

Children with malignancies are also at considerable risk. The risk of PE is more significant in children with solid rather than hematologic malignancies. PE has been described in children with Wilms tumor (tumor embolism) as well as leukemia. A child with malignancy may have numerous risk factors related to the primary disease process and the therapeutic interventions. Infection from chronic immunosuppression may interact with hypercoagulability of malignancy and chemotherapeutic effects on the endothelium.

In the neonatal period, thromboembolic disease and PE are often related to indwelling catheters used for parenteral nutrition and medication delivery. Emboli in neonates may occasionally reflect maternal risk factors, such as diabetes and toxemia of pregnancy. Infants with congenitally acquired homozygous deficiencies of antithrombin, protein C, and protein S are also likely to present with thromboembolic disease in the neonatal period.

Prothrombotic disease can also manifest in older infants and children. Disease can be congenital or acquired; DVT/PE may be the initial presentation. Factor V Leiden mutation (Chapter 472), hyperhomocysteinemia (Chapter 79.3), prothrombin 20210A mutation (Chapter 472), anticardiolipin antibody, and elevated values of lipoprotein A have all been linked to thromboembolic disease. Children with sickle cell disease are also at high risk for pulmonary embolus and infarction. Acquired prothrombotic disease is represented by nephrotic syndrome (Chapter 521) and antiphospholipid antibody syndrome. From one quarter to one half of children with systemic lupus erythematosus (Chapter 152) have thromboembolic disease.

Other risk factors include infection, cardiac disease, recent surgery, and trauma. Surgical risk is thought to be more significant when immobility will be a prominent feature of the recovery. Use of oral contraceptives confers additional risk, although the level of risk in patients taking these medications appears to be decreasing, perhaps as a result of the lower amounts of estrogen in current formulations.

Septic emboli are rare in children but may be caused by osteomyelitis, cellulitis, urinary tract infection, jugular vein or umbilical thrombophlebitis, and right-sided endocarditis.

Clinical Manifestations

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