Effects of Injection Site on the Accuracy of Thermal Washout: Discussion (4)
In relation to these considerations, Rapaport proposes that it is probably useless to inject the indicator into the atrium near the atrioventricular valve in an attempt to obtain better mixing, and on the other hand, atrial injection can cause inaccuracy in the measurement of residual fraction and therefore end-diastolic volume. Our results indicated that the EFs obtained from atrial injection might be more reproducible, but this does not mean these reflected true RVEFs. We suppose that the lower reproducibility in EFs obtained by ventricular injection may be caused by variation in EF values calculated from the latter part of a single thermal washout curve. buy birth control online
We cannot expect, on the one hand, complete mixing in the ventricle, and on the other, complete bolus movement of cold water to the ventricle without mixing in the atrium, even though the injection port in the atrium is just above the tricuspid valve. Irrespective of injection site, newly entering atrial blood does not mix completely with the ventricular contents in anesthetized dogs, and we think that a uniform concentration in the ventricle may be hard to obtain. However, Homer and Krayen-buehl propose less restrictive alternative conditions for accurate measurements of diastolic volume and this is applicable also to thermal washout method.