Ute Urban

A Novel Fully Implantable Wireless Sensor System for Monitoring Hypertension Patients

This paper presents a novel fully implantable wireless sensor system intended for long-term monitoring of hypertension patients, designed for implantation into the femoral artery with computed tomography angiography. It consists of a pressure sensor and a telemetric unit, which is wirelessly connected to an extracorporeal readout station for energy supply and data recording. The system measures intraarterial pressure at a sampling rate of 30 Hz and an accuracy of ±1.0 mmHg over a range of 30-300 mmHg, while consuming up to 300 μW. A special peel-away sheath introducer set was developed to support the implantation procedure. The system delivered stable measurements in initial animal trials in sheep, with results being in good agreement with reference sensor systems.

Polyurethane heart valves: past, present and future

Replacement cardiac valves have been in use since the 1950s, and today represent the most widely used cardiovascular devices. One type of replacement cardiac valve, the polyurethane heart valve, has been around since the first stages of prosthesis development, and has made advances along with the development of biological and mechanical heart valves over the past 60 years. During this time, problems with durability and biocompatibility have held back polyurethane valves, but progress in materials and manufacturing techniques can lead the way to a brighter future for these devices and their huge potential. This article describes previous efforts to manufacture polyurethane heart valves, highlights the challenges of manufacturing and explains the factors influencing durability and successful functioning of such a device.

Fully implantable blood pressure sensor for hypertonic patients

In Germany approximately ten million people suffer from high blood pressure. About 1% of these patients can hardly be stabilized on drugs and a long time monitoring is advisable. A system consisting of an implant and an external reader station is presented to realize a long term monitoring for these patients. The implant consists of a newly designed sensor chip integrated at the head of a catheter (Oslash 1.1 mm) and a telemetric unit. The sensor-tip is placed into the femoral artery while the telemetric unit is implanted into the subcutaneous tissue. Thus the disturbance inside the blood vessel and the distance for wireless communication are kept as small as possible to obtain optimal parameters. The implant is supplied with energy wirelessly via inductive coupling from the external reader station. Data is readout from the external station with approx. 30 Hz and an overall accuracy of plusmn 2 mbar.

A novel approach to an anatomical adapted stent design for the percutaneous therapy of tricuspid valve diseases: preliminary experiences from an engineering point of view.

Tricuspid valve regurgitation mostly occurs as result of dilation of the right ventricle, secondary to left heart valve diseases. Until recently, little attention has been given to the development of percutaneous therapeutic tools exclusively designed for tricuspid valve disease. A new approach to the interventional therapy of tricuspid regurgitation, in particular, the design of a conceptual new valve-bearing, self-expansible stent, is presented here. A three-dimensional computer model of a right porcine heart was developed to gain a realistic anatomical geometry. The new design consists of two tubular stent elements, one inside the superior vena cava and the other inside the tricuspid valve annulus after being eventually equipped with a biological valve prosthesis, which are connected by struts. Anchoring to the heart structure is provided primarily by the vena cava stent, strengthened by the struts. The stents are designed to be cut from a 10 mm tube and later expanded to their designated diameter. Simulation software analyzing the expansion process with respect to the intended geometrical design is used in an iterative process. A validation of the anatomical geometry and function of the stent design inside a silicone model within in vitro tests and a random porcine heart shows an accurate anatomical fitting.

Animal experimental evaluation of a new sealing device for indwelling arterial catheters.

Background Hematoma is a common complication following arterial puncture. To date no device that allows sealing of an arterial puncture site with in-situ catheter has been developed. Purpose To evaluate a newly developed arterial sealing device for endovascular catheters in an in-vivo experimental setting. Material and Methods A peelable collagen-based vascular sealing device for endovascular catheters was tested in acute (follow-up: 4 h; n = 2) and chronic (follow-up: 1 week; n = 4) settings in the femoral artery (FA) of sheep. After implantation correct position of the device as well as patency of the FA were verified angiographically. In the chronic group, hematoma was excluded and patency of FA was assured using color Doppler ultrasound 1 and 3 days after the procedure. After 1 week a final ultrasound and an angiography were performed for final evaluation. Thereafter, the animals were sacrificed and the puncture site was dissected and analyzed macroscopically. Results Sufficient sealing of the puncture site could be observed in all animals. In acute and chronic experiments, neither a hematoma at the puncture site nor other complications were observed after positioning the sealing device. Follow-up color Doppler ultrasounds (CDUS) and final angiography revealed patent FAs in all animals. Macroscopic evaluation of dissection material proved collagen plug and catheter being in place. Conclusion Our preliminary in-vivo results demonstrate a safe and convenient vascular sealing system for endovascular catheters. No acute or chronic complications were observed.

Anchoring percutaneous heart valves

Percutaneous heart valve replacement is an exciting and innovative technology which provides new treatment options for previously untreatable patients. Despite promising clinical results for the currently available prostheses by Edwards Lifesciences and Medtronic, these devices still require improvement in order to represent a true alternative to conventional heart valve replacement surgery. One of these challenges is the safe and effective anchoring of the catheter-delivered devices. This paper describes the development of an anchoring technique and highlights the key anatomical influence factors to be considered when designing percutaneous heart valve prostheses.

B1.2 - HYPER-IMS: A Fully Implantable Blood Pressure Sensor for Hypertensive Patients

Hypertension and heart failures were and are increasingly two of the main diseases of modern population. As a powerful tool for long-term post surgical evaluation of heart pressure, body temperature and pulse rate, a telemetric controlled sensor-implant without battery is currently developed and evaluated in the course of preclinical in-vivo experiments.