title: In vitro calibration and surgical implantation of electromagnetic blood flow transducers for measurement of left coronary blood flow and cardiac output in the pony.
abstract: Electromagnetic flow transducers were implanted via left thoracotomy in 8 ponies (122.7 to 263.6 kg) around the main pulmonary and left main coronary arteries for continuous measurement of mean and pulsatile blood flow. Flow transducers were calibrated in vitro with a gravity flow system. The mean +/- SE pulmonary flow was 73.1 +/- 5.1 ml/kg of body weight/min. Left coronary flow was 0.95 +/- 0.07 ml/kg/min (1.3% of cardiac output) and was not believed to be an accurate measurement. This was caused by the inability to implant a zero-flow occluder, requiring the use of minimum flow during systole as zero-flow base line. However, relative changes in left coronary flow were measured. Ponies were maintained up to 5 weeks with no adverse effects. Measurement of mean pulmonary flow with chronically implanted electromagnetic flow transducers provided an accurate continuous measurement of cardiac output with a minimum of restraint.
mesh_terms: D000818:Animals; D001783:Blood Flow Velocity / Q000662:veterinary; D002138:Calibration; D002302:Cardiac Output; D003326:Coronary Circulation; D055590:Electromagnetic Phenomena / Q000295:instrumentation; D005260:Female; D006736:Horses / Q000502:physiology*; D008297:Male; D014159:Transducers