Non-invasive estimation and control of inlet pressure in an implantable rotary blood pump for heart failure patients

We propose a dynamical model for mean inlet pressure estimation in an implantable rotary blood pump during the diastolic period. Non-invasive measurements of pump impeller rotational speed (ω), motor power (P), and pulse width modulation signal acquired from the pump controller were used as inputs to the model. The model was validated over a wide range of speed ramp studies, including (i) healthy (C1), variations in (ii) heart contractility (C2); (iii) afterload (C2, C3, C4), and (iv) preload (C5, C6, C7). Linear regression analysis between estimated and extracted mean inlet pressure obtained from in vivo animal data (greyhound dogs, N = 3) resulted in a highly significant correlation coefficients (R(2) = 0.957, 0.961, 0.958, 0.963, 0.940, 0.946, and 0.959) and mean absolute errors of (e = 1.604, 2.688, 3.667, 3.990, 2.791, 3.215, and 3.225 mmHg) during C1, C2, C3, C4, C5, C6, and C7, respectively. The proposed model was also used to design a controller to regulate mean diastolic pump inlet pressure using non-invasively measured ω and P. In the presence of model uncertainty, the controller was able to track and settle to the desired input within a finite number of sampling periods and minimal error (0.92 mmHg). The model developed herein will play a crucial role in developing a robust control system of the pump that detects and thus avoids undesired pumping states by regulating the inlet pressure within a predefined physiologically realistic limit.     

Exceptional association of hypocomplementemic urticarial vasculitis syndrome (HUVS) and symptomatic pulmonary histoplasmosis: a case-based literature review

Clinical Rheumatology - Hypocomplementemic urticarial vasculitis syndrome (HUVS) is a rare type III hypersensitivity disorder characterized by urticarial vasculitis and prolonged...     

Interventional management of vascular malformations

Vascular malformations are either of slow-flow type, including capillary, venous, and lymphatic lesions, or fast-flow, such as arteriovenous malformations. These anomalies are fundamentally congenital-though some may present later in life-, grow with the patient, and, with rare exceptions, do not disappear spontaneously. This article briefly discusses the diagnosis and interventional management of vascular malformations.     

The natural history of tunneled hemodialysis catheters removed or exchanged: a single-institution experience

PURPOSE: To track the natural history of tunneled hemodialysis catheters requiring removal or exchange at a single institution. MATERIALS AND METHODS: Over a 2-year period, tunneled hemodialysis catheters that presented to interventional radiology for removal or exchange were entered into this retrospective study. Patient demographics, catheter location, dwell time, and indication for removal were recorded. Pull-back contrast venography was performed with imaging over the chest. Catheters were then removed or exchanged. RESULTS: Three hundred thirty-four tunneled dialysis catheters were removed or exchanged in 207 patients; 108 male, median age 53 years. Dwell time, available from 296 catheters, ranged from 1 to 114 days (median, 66 days) for a total of 32,847 catheter days. One hundred three catheters were removed for infection, yielding a rate of infection requiring catheter removal of 3.0 per 1,000 catheter days. One hundred catheters were removed for other working access, and 96 catheters were exchanged for poor function. Two hundred sixty-five were removed or exchanged from the internal jugular vein, 22 from the subclavian vein, and 24 from the femoral vein. One hundred seventy-two (76%) of the 226 catheters studied with contrast had fibrin sheaths; of which 42 had thrombus identified along the catheter tract. One hundred ninety-three catheters were removed, and 141 catheters were exchanged for new catheters with 82 catheters receiving balloon disruption of the fibrin sheath. CONCLUSIONS: Approximately one third of tunneled dialysis catheters are removed for infection, one third for other working access, and one third for poor function. Catheters usually remain in the patient for a median of 2 months. Fibrin sheaths associated with hemodialysis catheters are very common. Thrombus formation around the sheath is frequent.     

Perinatal clinical and imaging features of CLOVES syndrome

We report a neonate with antenatal imaging features suggestive of CLOVES syndrome. Postnatal clinical and imaging findings confirmed the diagnosis, with the constellation of truncal overgrowth, cutaneous capillary malformation, lymphatic and musculoskeletal anomalies. The clinical, radiological and histopathological findings noted in this particular phenotype help differentiate it from other overgrowth syndromes with complex vascular anomalies.     

Liver transplantation amidst the COVID-19 era: Our center’s experience

Coronavirus disease 2019 significantly impacted the liver transplant process worldwide. Consequently, it brought significant challenges and limitations to transplant policies and organ allocation forcing liver transplant centers to adjust their protocols to ensure maximum benefit and avoid harm to their patients. Our center, like many others, was obliged to adapt to the challenges. This paper provided an overview of the effects of coronavirus disease 2019 on liver transplantations and detailed our center’s experience and efforts during this unprecedented pandemic to serve as a guide for future public health crises.