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Laboratory and Animal InvestigationsEffects of Heart Rate and Pulmonary Artery Pressure on Doppler Pulmonary Artery Acceleration Time in Experimental Acute Pulmonary Hypertension
Section snippets
METHODS
Nine Duroc 50- to 90-kg swine were anesthetized with intramuscular ketamine (25 mg/kg), endotracheally intubated, and maintained anesthetized on a ventilator using 0.5 to 2.0 percent halothane. Surgical cutdowns were performed on the right and left carotid arteries and veins. A 7.5-French (Fr) Could balloon-tipped flow-directed pulmonary artery thermodilution catheter was advanced under fluoroscopic guidance into the right pulmonary artery. An arterial pressure line was established in the right
RESULTS
The mean pulmonary pressure for anesthetized swine in sinus rhythm was 14 ± 4 mm Hg (see Table 1). The mean pulmonary artery pressure was easily varied by either bead injection or pulmonary clamping up to 45 mm Hg. Incremental injections of beads were performed at 30-minute intervals. This interval was chosen as it took about 30 minutes for the collection of data for all heart rates from 50 to 160 beats per minute at each pulmonary artery pressure. Attempts to raise mean pulmonary artery
DISCUSSION
We have developed a model of acute pulmonary hypertension in swine. Bead-induced pulmonary hypertension does not appear to be reversible. Pulmonary clamping produces reproducible elevations in mean pulmonary artery pressure, with the potential benefit of reversibility of the induced obstruction to pulmonary artery blood flow. Pulmonary artery pressure may be returned toward normal if unacceptable systemic hypotension occurs by removing the clamp. An additional characteristic of the pulmonary
ACKNOWLEDGMENT
The authors would like to acknowledge the superb technical assistance of Alice Allfie, the statistical assistance of Nathan Wong, Ph.D., and the laboratory space provided by Orhan Nalcioglu, Ph.D.
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2018, Journal of the American Society of EchocardiographyCitation Excerpt :These experiments revealed that increases in heart rate produced significant decreases in PA acceleration time at mean pressures < 25 mm Hg. However, with mean PA pressures > 25 mm Hg, both heart rate and increases in PA pressure had no significant effect on acceleration times.25 The description of normal pulsed Doppler flow velocities across the four cardiac valves made possible advances in quantitating intracardiac shunts and valvular regurgitant volumes.
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2018, Journal of the American Society of EchocardiographyCitation Excerpt :In adults, PAAT correlates inversely with heart rate in healthy control subjects, and many studies have corrected PAAT for RV ejection time, RR interval, or the square root of the RR interval. Nevertheless, at any given heart rate, PAAT shortened as PAP increased up to a mean of >25 mm Hg.35 RV systolic function and RV preload should affect PAAT, but only three studies reported RV function by tricuspid annular plane systolic excursion or RV fraction area change in the trials that we collected.
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2016, IJC Heart and VasculatureCitation Excerpt :Heart rates outside of the normal range (< 60 or > 100 bpm) may reduce the accuracy of this technique. However, when the mean PAP exceeds 25 mmHg, RVOT acceleration time is accurate even in tachycardia [19,20]. More often, the slope of the pulse wave Doppler trace is measured, rather than the time taken from onset to peak velocity.