title: A constant-field interrupted resonance system for percutaneous electromagnetic measurement of blood flow.
abstract: A combination of deformable flow probes of negligible lateral dimensions with an electronic circuit capable of providing a prolonged plateau of dB/dt = 0 and of sampling the flow signal at the end of this interval permits electromagnetic measurement of blood flow with a reliable zero base line secured by switching off the magnet. An extracorporeal magnet provides the magnetic field. The flow transducer is introduced into the vascular system percutaneously through a standard angiographic catheter by conventional technique. The idea of the current generator can be described as "principle of interrupted resonance." The current wave form can be described as a sequence of disconnected bisected sine waves joined at the apices by horizontal current plateaus where di/dt is strictly zero.
mesh_terms: D000818:Animals; D001783:Blood Flow Velocity; D002404:Catheterization; D004285:Dogs; D055590:Electromagnetic Phenomena / Q000295:instrumentation*; D006801:Humans; D008722:Methods; D012212:Rheology / Q000295:instrumentation*; D014159:Transducers