Interventional magnetic resonance (IMR) using high-field (1.5T) is becoming a routine procedure for clinical examinations in many European cardiovascular departments. A limitation in endovascular interventions, however, has been the use of conventional catheters. Usually fabricated with among other items, metal wire, there is a risk that they might heat up when used in an MR scanner, with potentially harmful consequences for the patient.
University Hospital (Utrecht, the Netherlands) has successfully developed catheters which use fiber optics instead of conducting wires for the MR micro-coils integrated into the tip of the catheter and used to track the catheter and image the vessel wall. With these catheters, the heating problem associated with conventional catheters in an MR system is avoided, overcoming a major obstacle in the use of IMR procedures in humans. The hospital, which has worked closely with Philips Medical Systems (Best, the Netherlands) in developing the new catheters, currently has two 1.5 tesla MR scanners and two smaller 0.5T units.
The radiology diagnostic clinic at Rheinisch-Westf lische Technische Hochschule (RWTH; Aachen, Germany) is a major German center in the development of cardiovascular MR techniques. Of the three MR scanners at RWTH, one is an Intera I/T unit from Philips and specially designed for interventional procedures. The MR scanner is also designed for use with a BV-212 X-ray angiography C-arm, located outside the 5-gauss magnetic field strength line, which can be used in cases where both X-ray and MR guidance for the same procedure is beneficial. In a number of trials, RWTH has been able to demonstrate the feasibility of fully MR-guided endovascular procedures, including coronary angioplasty with stent placement and insertion of an umbrella PFO (patent foramen ovale) catheter to close a septal defect. Both procedures have been used successfully in animal applications.
Professor Albert van Rossum of the department of cardiology at the Free University Medical Center (Amsterdam, the Netherlands) pointed out at last September's European Society of Cardiology congress that cardiovascular magnetic resonance (CMR) has now become a tool to predict viability of the myocardium. CMR technology has now improved, he said, to a point where a single examination can provide images of the anatomy of the heart, of its remaining capacity to expel blood into the vascular system and of the presence of dysfunctional, though still viable, segments of the heart wall injured by myocardial infarcts. He cited patient studies at Northwestern University School of Medicine (Chicago, Illinois) demonstrating that CMR after administration of contrast media can distinguish between reversible and irreversible myocardial injury.
In Amsterdam and several other European cardiology centers, this contrast-enhanced CMR of the myocardium is proving to be a very reliable technique, providing excellent image quality with little failure, van Rossum said. It can be easily combined with CMR techniques to assess the pump function of the heart, blood flow and coronary artery anatomy. Based on this experience van Rossum considers that CMR is likely to become the imaging technique of choice in management of patients with chronic ischemic heart disease and heart failure.
SQUID (Essen, Germany) is a leader worldwide in the development of magnetocardiography as a noninvasive approach to diagnosis in cardiology. The medical indications range from early coronary artery disease diagnosis, differential diagnosis of chest-pain, evidence of myocardial infarction, monitoring of percutaneous transluminal coronary angioplasty and pharmacological treatment following heart surgery.
Following SQUID's initial development of magnetocardiographic systems for unshielded environments, the design of the new mobile system provides the means to potentially enlarge the application field, according to company personnel. The mobile unit is designed to operate anywhere in Europe and beyond. It has its own power supply unit, which allows operation without external electric power supplies. The truck is a modified Mercedes-Benz Sprinter 316 with diesel engine. A total maximum weight of under 7.5 tons will allow driving with a normal drivers license in most European countries.
Mobile MRI in central Europe
Neuromed (Castrop-Rauxel, Germany) in December started a new mobile cardiac MRI service for hospitals, clinics and cardiologists in the Czech Republic, Hungary, Slovakia and adjacent countries. The new cardiac MRI system complements an existing fleet of mobile computed tomography, MRI, cath lab and positron emission tomography systems.
The new service provides the first dedicated cardiac MRI system in central Europe, which is installed in a specially designed mobile trailer from SMIT (Oud Beijerlein, the Netherlands). A 1.5T cardiac MRI system (Signa CV/i1.5T) from GE Medical Systems (Waukesha, Wisconsin) is installed, together with a film viewing box and a Drystar 3000 dry imaging laser camera from Agfa Gavaert (Mechelen, Belgium).
Cascade blood filtration for ICUs
Infomed (Geneva, Switzerland) is developing the new HF400 blood filtration system which also incorporates a double filtration treatment program. Double filtration, or cascade, consists in removing plasma from blood through the first filter and then passing the plasma through a second filter. This makes possible the return of "small" molecular products such as albumin and HDL cholesterol to the patient while retaining "large" molecule products such as LDL cholesterol.
The original method, first developed in Japan in the 1980s, can treat a range of conditions, the most common of which is hypercholesterolemia. However, the cascade filter separating large from small molecules becomes clogged up during operation and, in the original method, was cleaned continuously using part of the plasma. To increase efficiency external albumin must be added, contraindicated in some conditions.
The HF400 system improves treatment efficiency with an alternative cleaning system based on a concept from Dr. Branger of Nimes, France. As soon as the cascade transmembrane pressure reaches a preset value, the treatment stops, the filter is rinsed using a saline fluid and the treatment restarts. As a result, external albumin is not needed in most cases, widening the area of application. First published results using the HF400 should be presented at the next International Apheresis Society meeting in Paris later this year.
Single-sensor PCO2 and SpO2 system
The Tosca probe from Linde Medical Sensors (Basel, Switzerland) is attached to the earlobe using a specially designed low-pressure sensor clip. The combined sensor includes elements of a Stow-Severinghaus type carbon dioxide sensor and an optical pulse oximetry sensor. Heating the sensor to a constant 42 C achieves optimal arterialization of the cutaneous tissue needed for transcutaneous PCO2 measurement. It also improves the signal-to-noise ratio of the optical SpO2 measurement.
The company claims the clinical results obtained demonstrate that the performance of the SpO2 measurement is significantly improved particularly in situations of low signal-to-noise ratio during low perfusion and movement artefacts. Observed improvements include a shorter in vivo reaction time, increased sensitivity during SO2 or PCO2 changes, a higher stability of the SpO2 signal and a shorter arterialization time for the PCO2 measurement, Linde said.
Fetal monitoring technique
The STAN S21 fetal heart monitor from Neoventa Medical (Bury, England) combines fetal cardiotocography (CTG) monitoring with ST analysis to accurately identify fetal oxygen deficiency. A Swedish multicenter trial involving almost 5,000 pregnant women showed a 53% reduction in the number of neonates with metabolic acidosis using CTG+ST analysis (the so-called STAN method). In addition, the number of babies born with neurological symptoms fell from 0.33% to 0.04%.
Professor Karel Marsal, who led the trials, said that the number of Caesarean sections and instrumental deliveries for fetal distress was also reduced. He added, "To our knowledge, this is the first report showing a new fetal monitoring methodology capable of reducing the risk of babies being exposed to severe intrapartum oxygen deficiency."
Beating-heart surgery safe and effective
Peter de Jaegere and his team at University Medical Center (Utrecht, the Netherlands) have published results in Circulation of a 281-patient study comparing coronary bypass surgery with beating-heart (off-pump) and traditional techniques using a heart-lung machine (on-pump).
Although de Jaegere found that the beating-heart technique using Medtronic's (Minneapolis, Minnesota) Octopus tissue stabilizer was more demanding than operating on a stopped heart (on-pump), 13% of the on-pump group needed transfusions during the procedure, compared to only 3% of off-pump patients. Hospitalization for off-pump patients was one day less than for on-pump patients, while procedure costs were on average 12% more in off-pump patients.
Bracco launches U/S platform, contrast agent
The Bracco group (Milan, Italy) has launched a new ultrasound-based diagnostic system for use in oncology and cardiovascular sectors. The new Esatune system consists of the Megas U/S platform developed by Esaote (Firenze, Italy), a subsidiary of Bracco, along with Bracco's second-generation Sonovue contrast agent and a new combined hardware/ software image enhancement system called Contrast Tuned Imaging. The initial European launch was in Britain, Germany and Italy, with a second wave in France, the Benelux countries and Spain set for early this year.
White coat syndrome
The "white coat syndrome," well-known to the medical profession, reveals itself through a rise in blood pressure measurements when taken in medical surroundings, such as a physician's office or clinic.
"When a patient presents with this syndrome," said Professor Girard of the Broussais Hospital (Paris), "I ask him to take his blood pressure measurements himself over a period of three days morning and evening, in a sitting position." The patient takes each series of readings before each consultation. "This allows us to work with readings closer to reality, so that we can adapt the therapy most effectively."