Using medical implants to wirelessly report physiological data is a technique that is rapidly growing. Ultrasound is well-suited for implants --it requires little power and this form of radiated energy has no ill effects on the body. We report here on techniques we have developed in our experience gained in implanting over a dozen Doppler ultrasound flow-measuring implants in dogs.The goal of our implantable device is to measure flow in an arterial graft. To accomplish this, we place a Doppler transducer in the wall of a graft and an implant unit under the skin that energizes the 20 MHz Doppler transducer system, either when started by external command or by internal timetable. The implant records the digitized Doppler real and imaginary channels and transmits the data to a nearby portable computer for storage and evaluation.After outlining the overall operation of the system, we will concentrate on three areas of implant design where special techniques are required: ensuring safety, including biocompatibility to prevent the body from reacting to its invasion; powering the device, including minimizing energy used so that a small battery can provide long-life; and transmitting the data obtained.

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Endovascular stent grafts for the treatment of thoracic aortic aneurysms have become increasingly utilized and yet their locational stability in moderate chest trauma is unknown. A high speed impact system was developed to study the stability of aortic endovascular stent grafts in vitro. A straight segment of porcine descending aorta with stent graft was constrained in a custom-made transparent urethane casing. The specimen was tested in a novel impact system at an anterior inclination of 45 deg and an average deceleration of 55 G, which represented a frontal automobile crash. Due to the shock of the impact, which was shown to be below the threshold of aortic injury, the stent graft moved 0.6 mm longitudinally. This result was repeatable. The presented experimental model may be helpful in developing future grafts to withstand moderate shocks experienced in motor vehicle accidents or other dynamic loadings of the chest.

Thrombosis is one of the major underlying pathogenetic mechanisms leading to increased morbidity and mortality among COVID-19 patients. Thromboembolic events as well as severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) are the major causes of death in this continued pandemic. While elevated D-dimer level suggests worse thrombotic outcomes, levels at which benefits of anticoagulation outweigh the bleeding risk is yet to be determined. In this report, we present a case of a 72-year-old man with COVID-19 presented with confusion and subsequently developed acute hypoxic respiratory failure. On hospital day 7, patient developed extensive peripheral arterial thrombosis with acute rise of D-dimer from 800 to 14,899 ng/ml. He was treated with heparin drip and underwent urgent brachial, radial and ulnar embolectomy under general anesthesia. In this report, we also discuss the pathogenetic mechanisms and management of thromboembolism in COVID-19 patients, highlighting the role of early detection and aggressive therapeutic interventions that could be life and / or limb saving strategy.

The coronavirus disease 2019 pandemic has impacted millions of people worldwide. This novel virus has a variety of presentations and complications. Notably, patients with this infection have an associated coagulopathy, presenting with symptoms such as gastrointestinal bleeds, deep vein thrombosis, ischemic cerebrovascular events, and pulmonary embolism. Although there are documented cases of venous thromboembolism in patients with coronavirus disease 2019, the authors present an interesting case of upper extremity arterial thromboembolism in a 75-year-old patient surgically treated for arterial thrombus removal. We also discuss diagnosis, medical management, and surgical approach to an upper extremity arterial thromboembolism in a patient with coronavirus disease 2019, to highlight the challenges of hypercoagulability in such patients.

A high speed impact system was developed to study the stability of stent grafts in thoracic porcine models in vitro. The experiments were guided by a finite element model of the test setup to identify the conditions that increase the risk of instability of the stent graft. The models showed that at anterior inclination of 45° and average deceleration of 40 G, which represented a frontal crash, the stent graft can move up to 1 mm. The results of this study may be helpful in developing future grafts to withstand shocks experienced in motor vehicle accidents.

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