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

The research article focuses on an experiment regarding the implantation of electromagnetic blood flow transducers in ponies in order to continuously measure blood flow in the main pulmonary and coronary arteries. The results show that this method accurately measures cardiac output with less restraint for the animal, even though it reportedly had some challenges in accurately measuring zero-flow base line.

Experiment Process

• The electromagnetic flow transducers were surgically inserted into 8 ponies via a procedure known as left thoracotomy, a type of surgery that accesses the chest cavity. These transducers were placed around the main pulmonary artery and the left main coronary artery.
• Before the implantation, the flow transducers were calibrated in a controlled laboratory environment with a gravity flow system to ensure their accuracy.

Findings on Cardiac Flow

• The researchers then measured both the mean and pulsatile blood flow in the ponies continuously, and found that the mean pulmonary flow was 73.1 +/- 5.1 ml/kg of body weight per minute.
• They also noticed relative changes in the left coronary flow, which they monitored and recorded.

Implantation Challenges

• Despite these successful measurements, the study encountered a problem with accurately measuring left coronary flow as it was unable to implant a zero-flow occluder.
• This occluder would have established a baseline measurement for when there is no blood flow (zero-flow). Without this baseline, the researchers were forced to use the minimum flow during the heart’s contraction phase (systole) as a surrogate for zero-flow, which they noted might not be completely accurate.

Pony Welfare During and After the Study

• The researchers observed and recorded their subjects closely, noting no adverse effects on the ponies following the procedure. They kept the transducers implanted for a duration of up to 5 weeks.
• They concluded that utilizing implanted electromagnetic flow transducers provided an accurate and continuous method of measuring cardiac output that imposed minimal restraint and discomfort on the animals.