Intravascular Monitoring System for Hypertension Patients "HyperPLUS"
Hypertension is an important risk factor for vascular diseases (artherosclerosis), renal and heart insufficiency. Approximately ten million patients in Germany suffer from hypertension; 10% of these patients are difficult to medicate, whereas 1% require long-term blood pressure monitoring.
Presently, there are different systems available for blood pressure measurement. Principally, the methods of blood pressure measurement can be distinguished into two groups; indirect (extracorporeal) and direct (invasive). The indirect blood pressure measurement can be measured quickly by means of an inflatable sleeve on the arm or leg (Riva Rocci), or even long term blood pressure measurement for more than 24 hours. These extracorporeal systems are cumbersome, uncomfortable, and stressful for patients, especially overnight. A further disadvantage is the low data acquisition rate. Invasive blood pressure measurement systems exhibit sensors (TIP-catheter), which are inserted by means of a catheter into an artery in the forearm. When considering the application of these systems, drift and inadequate dynamical behavior may generate faulty pressure data. Another method deals with blood pressure measurement by means of fluid-filled catheters, however drifts and inaccuracies in the pressure measurement may also occur. Additionally, the risk of inflammatory infection increases.
The goal of this BMBF sponsored project was the development of a novel monitoring system, which quasi-continuously records the blood pressure, pulse rate and body temperature of hypertensive patients over a 6 month period.
The system consists of an implantable pressure sensor (outer diameter 1mm (3F)) with a 30 Hz sample rate. The implantation should be accomplished by means of a sheath in the arteria femoralis under X-ray-control. The sensor is connected to the transponder unit via a flexible wire (Figure). A data read-out-station, designed as an extracorporal portable unit, respectively transmits wireless energy to the transponder and receives digitised sensor data. For data visualisation and evaluation, the pressure, pulse and temperature data recorded may be downloaded from the read-out-station to a monitoring-station.