However, this and other studies relating PA acceleration time to PA pressure have been performed primarily in patients not exhibiting tachycardia. Since it might be expected that increased heart rate would shorten time-based measurements such as acceleration time and ejection time, we evaluated the use of the PA AT/ET ratio as a technique for correcting for increased heart rate. A similar approach would involve correcting for heart rate directly by dividing PA AT by the square root of R-R interval. Although using the AT/ET ratio is helpful in solving one of the problems associated with PA acceleration time measurements, many other problems must be considered. generic wellbutrin
First, various investigators have noted that the position of the Doppler sample volume in the pulmonary artery may affect the PA acceleration time measurement Specifically, recording from near the PA wall or distally in the pulmonary artery toward its bifurcation may lead to erroneously decreased measurements of acceleration time. In the current study, we recorded from the parasternal view near the pulmonic valve, centrally in the vessel, and angulated the transducer to obtain the PA velocity tracings having the least spectral dispersion and highest peak flow velocity. This technique minimized the possibility of recording erroneously short measurements of PA acceleration time. However, it has recently been pointed out in human subjects that the highest flow velocity in the pulmonary artery may frequently be recorded from a subcostal approach. Nonetheless, since we recorded from the same parasternal position at all paced rates, our conclusions regarding changes in the flow velocity measurements should remain valid. In addition, we sought to overcome the effects of respiration on PA flow velocity measurements by measuring the complexes that demonstrated the highest peak flow velocities.
Category: Pulmonary Artery
Tags: heart rate, porcine model, pulmonary artery