We investigated a miniature magnetically levitated centrifugal blood pump intended to deliver 0.3-1.5 l/min of support to neonates and infants. The back clearance gap between the housing and large volume of the rotor, where the suspension and motor bearings are located, forms a continuous leakage flow path. Within the gap, flow demonstrates a very complex three-dimensional structure: the fluid adjacent to the rotating disk tends to accelerate by centrifugal force to flow radially outwards toward the outlet of the impeller against an unfavorable pressure gradient, which in turn forces blood to return along the stationary housing surfaces. Consequently, one or multiple vortices may be generated in the gap to block blood flow and cause the formation of a retrograde and antegrade leakage flow phenomenon at the gap outlet using an optimization process including extensive computational fluid dynamics (CFD) analysis of impeller refinements, we found that secondary blades located along the back or extended to the side surfaces of the rotor have the capacity to reduce and eliminate the retrograde flow in the back clearance gap. Flow visualization confirmed the CFD-predicted flow patterns. This work demonstrates the utility of CFD-based design optimization to optimize the fluid path of a miniature centrifugal pump.
Duchenne muscular dystrophy (DMD) is an X-linked recessive disorder affecting 1 in 3,500 males, characterized by progressive skeletal muscle weakness and death secondary to cardiac or respiratory failure in the 2nd or 3rd decade. Being a progressive disease, patients are rarely candidates for cardiac transplantation and death from dilated cardiomyopathy (DCM) is common. Implantation of left ventricular assist device (LVAD) offers the potential to alter clinical trajectory by alleviating heart failure symptoms. We report implantation of HeartMate II device in a 29-year-old male patient and HeartWare device in a 23-year-old female patient, each with DMD and end-stage DCM. By improving cardiac output, we were able to achieve resolution of the symptoms of heart failure and improve their quality of life. Preoperative planning and patient selection played a significant role in the postoperative course for these patients. These cases represent the first use for each device in this patient population and the first reported LVAD implantations in patients with DMD in North America.
Barth syndrome (BTHS) is associated with myocardial disease, frequently left ventricular noncompaction cardiomyopathy, which may necessitate cardiac transplantation or lead to death in some patients. We report a child with BTHS who had an "undulating cardiac phenotype" and ultimately developed decompensated heart failure requiring mechanical circulatory support with a ventricular assist device as a bridge to transplantation. His course was complicated by acute lung injury requiring placement of an in-line oxygenator to maintain end-organ function. Not only was his course complicated by cardiac and respiratory failure but his BTHS associated comorbidities complicated the management of his therapy using mechanical assist device support. He was successfully supported and subsequently was transplanted. Here we discuss the management of a child with BTHS using mechanical circulatory support and describe the use of an in-line oxygenator, Quadrox, with the Berlin Excor device.
Children with cardiac disease supported with ECMO who acquire fungal infections have increased mortality. Routine fluconazole prophylaxis is associated with lower rates of fungal infections in these patients.
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