Mathematical analysis of the effects of valvular regurgitation on the pumping efficacy of continuous and pulsatile left ventricular assist devices.

BACKGROUND: A left ventricular assist device (LVAD) is normally contraindicated in significant aortic regurgitation (AR) and requires intraoperative valve repair or exclusion. Nevertheless, AR can coexist with an LVAD, so a valid question when asked might still be of clinical significance. The purpose of this study is to analyze the effects of valve regurgitation on the pumping efficacy of continuous and pulsatile LVADs with a computational method. METHODS: A cardiovascular model was developed based on the Windkessel model, which reflects the hemodynamic flow resistance and the blood wall elasticity. Using the Windkessel model, important cardiovascular components, such as the right atrium, right ventricle, pulmonary artery, pulmonary vein, left atrium (LA), left ventricle (LV), aorta, and branching blood vessels, were expressed. RESULTS: In the case of AR, continuous and pulsatile LVADs improved cardiac output and reduced mechanical load slightly. In the case of mitral regurgitation, the LVADs improved cardiac output (cardiac outputs were about 5 L/min regardless of the severity of regurgitation) and reduced afterload significantly. CONCLUSION: AR reduced both continuous and pulsatile LVAD function significantly while mitral regurgitation did not affect their pumping efficacy.

Ocular ischemia and ischemic oculomotor nerve palsy after vascular embolization of injectable calcium hydroxylapatite filler.

A healthy 25-year-old man who received a calcium hydroxylapatite filler injection for nose augmentation by a dermatologist suddenly developed blepharoptosis and orbital pain on the right side, associated with progressive visual disturbance of the right eye. Patchy necrosis at the nose and glabella, limitations of extraocular movements, and anterior segment ischemia, as evidenced by conjunctival injection, chemosis, corneal edema, dilated pupil, hyphema, and hypopyon, were noted. Orbital CT demonstrated linear deposits of a similar density to bone in the right medial orbit and eyelid, suggestive of multiple emboli along the conjunctival vessels. A provisional diagnosis of ocular ischemia and ischemic oculomotor nerve palsy secondary to vascular embolization was made. After 3 months, visual acuity, all intraocular inflammation, oculomotor nerve palsy, and skin necrosis resolved completely except for a dilated pupil.