EXPLANATION


Though less common in children than adults, pulmonary embolism (PE) is associated with significant morbidity and mortality. Guidelines for management of acute pulmonary embolism in children are based on those created for adults, due to the more established literature in this population. In most guidelines, risk stratification of pulmonary embolism is the initial step in the diagnostic and treatment algorithm. High risk (massive) pulmonary embolism is typically defined as having signs of severe cardiopulmonary dysfunction or obstructive shock, such as tachycardia, hypotension, and altered mental status. Intermediate risk (sub massive) PE typically lacks signs of obstructive shock but retains the signs of right ventricular (RV) strain as evidenced by echocardiography and electrocardiogram, or elevated cardiac enzymes.


Signs and symptoms of PE in children may differ from those in adults. Children often have a delayed presentation due to an increased ability to physiologically compensate as compared to adults, non-specific symptoms, and difficulty in symptom communication. These signs and symptoms include chest pain, dyspnea, hypoxemia, cough, hemoptysis, or more severely, hypotension, tachycardia, and cardiac arrest. There should be a high index of suspicion in children with risk factors for PE, which include use of oral contraceptives, hypercoagulable state, presence of an indwelling central venous catheter, obesity, malignancy, sickle cell anemia, and sepsis.


Severe pulmonary embolism causes an acute increase in pulmonary artery pressure based on the degree of obstruction. Acute RV dysfunction or failure can lead to RV dilation, tricuspid regurgitation, left ventricular (LV) dysfunction, and cardiac arrest. The combination of systemic hypotension and increased RV pressure leads to a decrease in myocardial oxygen supply with increased demand that results in a downward spiral of myocardial ischemia followed by further mismatch in myocardial oxygen supply and demand. Useful laboratory values include d-dimer, coagulation studies, and cardiac enzymes. The electrocardiogram will often show signs of right ventricular strain. Echocardiography may demonstrate the pulmonary embolism and indirect signs of acute pulmonary hypertension with tricuspid regurgitation, RV dilation, and RV systolic dysfunction. When risk factors, clinical signs and symptoms, and laboratory values suggest a high probability of PE, computed tomography pulmonary angiography (CTPA) is considered the diagnostic test of choice.


In patients with severe high-risk pulmonary embolism, systemic thrombolysis with thrombolytic agents such as tissue plasminogen activator (tPA) has been shown to improve outcomes. This is reflected in guidelines recommending this treatment, with the greatest benefit being initiation within 24 hours of symptom onset. Surgical embolectomy (SE) or catheter-based embolectomy (with or without catheter directed thrombolytic treatment) may also be considered in severe cases, though evidence on outcomes is less robust. In patients with intermediate risk PE, systemic thrombolysis may be associated with less progression of symptoms but is associated with increased risk for severe intracranial bleeding. Retrospective studies in adults have found equivalent short- and long-term mortality between patients receiving systemic thrombolysis versus surgical embolectomy. These studies have found that the thrombolysis patients experienced more stroke, reintervention, and recurrence, as compared to the SE group, which experienced a higher rate of major bleeding. A small retrospective study in children showed similar mortality rate between thrombolysis and SE but higher rates of non-fatal major hemorrhage in patients undergoing SE. Other practical considerations in choosing management are the timing and availability of a surgical team versus catheterization team, how distal the embolus resides, and if the patient has contraindications to systemic thrombolysis.


Given the severity of the signs and symptoms in this patient consistent with a high-risk massive PE with hemodynamic compromise, thrombolytic intervention with tissue plasminogen activator would be indicated to prevent further decompensation. Unfractionated heparin alone would not be sufficient for a high-risk PE but may appropriate for intermediate risk PE. Warfarin alone would not be an appropriate treatment in a patient with high-risk PE because it requires administration for 5 to 7 days to achieve a therapeutic level and has a transient procoagulant effect during initial administration requiring coadministration with either unfractionated heparin or low molecular-weight heparin.


REFERENCES


Ross C, Kumar R, Pelland-Marcotte MC et al. Acute Management of High-Risk and Intermediate-Risk Pulmonary Embolism in Children: A Review. Chest. 2022 161(3):791-802. doi: 10.1016/j.chest.2021.09.019.


Zaidi AU, Hutchins KK, Rajpurkar M. Pulmonary Embolism in Children. Front Pediatr. 2017;5:170. doi: 10.3389/fped.2017.00170.


Ortel TL, Neumann I, Ageno W, et al. American Society of Hematology 2020 guidelines for management of venous thromboembolism: treatment of deep vein thrombosis and pulmonary embolism. Blood Advances. 2020;4(19):4693-4738.


Konstantinides SV, Meyer G, Becattini C, et al. 2019 ESC Guidelines for the diagnosis and management of acute pulmonary embolism developed in collaboration with the European Respiratory Society (Ers). Eur Heart J. 2020;41(4):543-603.


Navanandan N, Stein J, Mistry RD. Pulmonary Embolism in Children. Pediatr Emerg Care. 2019:35(2): 143-151.