In vitro calibration and surgical implantation of electromagnetic blood flow transducers for measurement of left coronary blood flow and cardiac output in the pony.
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.
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