Mechanical circulatory support (MCS) provides a bridge to heart transplant in children and adults with life-threatening heart failure and sustains patients ineligible for transplant. Extracorporeal membrane oxygenation (ECMO) provides temporary support for patients in cardiac or pulmonary failure through external gas exchange and continuous flow of blood. Because the median time to heart transplant exceeds event-free time on ECMO, pulsatile left ventricular assist devices (LVADs) are used to support infants and children. Continuous flow LVADs are preferred in adolescents and adults due to increased pump durability and improved overall survival. The shear stress created by the mechanical pumps cause changes in the hematologic system; acquired von Willebrand syndrome occurs in almost all patients treated with MCS. Despite the improvements in survival, major bleeding occurs in one-third of patients with a LVAD and ischemic stroke and LVAD thrombosis can affect 12% of adults and 29% of children. An antithrombotic strategy to mitigate LVAD bleeding and thrombotic complications has been tested in a randomized trial in children, but intensity of antithrombotic therapy in adults varies widely. Consensus guidelines for antithrombotic therapy during ECMO were created due to significant differences in management across centers. Because of the high risk for both bleeding and thrombotic complications, experts in hemostasis can significantly impact care of patients requiring mechanical circulatory support and are a necessary part of the management team.
Learning Objectives• Understand available options for mechanical circulatory support and the impact of mechanical circulatory support on the hematologic system • Differentiate the bleeding and thrombotic risks between children and adults requiring mechanical circulatory support • Recognize possible treatment options for mechanical circulatory support thrombosis Heart failure affects Ͼ5 million adults in the United States (US) and 23 million people globally. 1 The incidence of heart failure in children is significantly less than adults with ϳ18 admissions per 100 000 children per year; however, there is significant economic impact of pediatric heart failure given the frequent need for surgical intervention and the loss of productive years in the event of a child's death. 2 The heart failure etiology also differs with age as most children have congenital heart disease and adults experience cardiomyopathy or coronary artery disease. 1