Effect of Acute Changes in Heart Rate on Doppler Pulmonary Artery Acceleration Time in a Porcine Model

Doppler measurements of pulmonary artery (PA) acceleration time (AT) have been used clinically to estimate PA pressure. However, these studies have been performed primarily in patients without tachycardia. To determine the effect of acute changes in heart rate on PA AT, atrial pacing studies were performed in seven closed-chest pigs. Pulsed Doppler PA flow velocity recordings were obtained from a parasternal position at pacing rates from 100 to 140 beats/min. PA pressure remained constant (mean ± SD = 14 ± 5 mm Hg) over the entire range of paced rates. When PA Doppler measurements were compared at heart rates of 100 and 140 beats/min, there were decreases at the higher heart rate in both acceleration time (110 ± 12 vs 83 ± 11 ms, p