Pressure Wave Transmission in the Human Pulmonary Circulation

. Direct and series transmission of left atrial pressure perturbations to the pulmonary artery: a study using wave-intensity analysis. Am J Physiol Heart Circ Physiol 286: H267-H275, 2004. First published September 25, 2003 10.1152/ ajpheart.00505.2002-Pressure waves are thought to travel from the left atrium (LA) to the pulmonary artery (PA) only retrogradely, via the vasculature. In seven anesthetized open-chest dogs, a balloon was placed in the LA, which was rapidly inflated and deflated during diastole, early systole, and late systole. High-fidelity pressures were measured within and around the heart. Measurements were made at low volume [LoV; left ventricular end-diastolic pressure (LVEDP) ϭ 5-9 mmHg], high volume (HiV; LVEDP ϭ 16-19 mmHg), and HiV with the pericardium removed. Wave-intensity analysis demonstrated that, except during late systole, balloon inflation created forwardgoing PA compression waves that were transmitted directly through the heart without measurable delay; backward PA compression waves were transmitted in-series through the pulmonary vasculature and arrived after delays of 90 Ϯ 3 ms (HiV) and 103 Ϯ 5 ms (LoV; P Ͻ 0.05). Direct transmission was greater during diastole, and both direct and series transmission increased with volume loading. Pressure waves from the LA arrive in the PA by two distinct routes: rapidly and directly through the heart and delayed and in-series through the pulmonary vasculature. lung; arteries; hemodynamics; wave transmission WAVE TRANSMISSION through the heart is poorly understood. Among the clinical syndromes in which wave transmission could be an important, unappreciated factor are the stiff left atrium (LA) syndrome (6, 15) and the Bernheim syndrome (1,5,24). To study the transmission of waves generated in the LA, we created a system where a backward-going wave, originating from the LA, could be detected in the proximal pulmonary artery (PA; backward and forward are defined with respect to PA flow.) To create such a wave in a controlled fashion, we used an LA counterpulsation balloon. Pressure and velocity waveforms in the proximal PA were analyzed to evaluate the effects of LA pressure (P LA ) perturbations.Most commonly, pulsatile arterial phenomena have been characterized using Fourier analysis where the observed waveforms are decomposed into sinusoidal wave trains, and the results are expressed as amplitude and phase as a function of frequency (16,17). This frequency-domain analysis has provided much information. However, wave-intensity analysis where the observed waveforms are decomposed into a succession of infinitesimal wave fronts that are described by their amplitude and time (13,19) allows the interaction of forwardand backward-going waves and their relation to primary hemodynamic parameters (pressure, flow, etc.) to be studied directly. This method utilizes changes in pressure and velocity to evaluate the direction, intensity, and type of waves and has been used recently to study the systemic (18), pulmonary (8,11,22), and coronary circulations...

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“…8B). Series transmission was dependent on P PA , likely because vascular compliance decreased as pressure increased (2,6).…”

Section: Discussionmentioning

confidence: 99%

Direct and series transmission of left atrial pressure perturbations to the pulmonary artery: a study using wave-intensity analysis

Hollander¹,

Dobson²,

Wang³

et al. 2004

American Journal of Physiology-Heart and Circulatory Physiology

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“…Damping decreases the magnitude of the modulus and the angle of harmonic form of the PA pressure wave in terms of Fourier coefficients. The attenuating factor, which was used to derive the decreased moduli due to damping, was obtained from a previous human study 15 in which decreases in magnitude of modulus, as a forward transmission ratio (amplitude of pulmonary vein wedge pressure as a percentage of amplitude of the PA pressure), were measured at the frequencies of the harmonics in subjects with and without various degrees of pulmonary hypertension. The forward transmission ratio was found to vary depending on the frequencies of the harmonics (appendix).…”

Section: Methodsmentioning

confidence: 99%

“…The transmission ratios are as follows: when the frequency is between 1 and 2, the ratio is 32.8%; between 3 and 4, 24.8%; between 4 and 5, 46.2%; and between 5 and 6, 25.6%. 15 2. A decrease in the angle: The decreased angle is as follows 41 :…”

Section: Appendix: Calculation Of Pa Output Pressure With Applicationmentioning

confidence: 99%

Increased Pulmonary Venous Resistance in Morbidly Obese Patients without Daytime Hypoxia

et al. 2010

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“…Compared with PWV in the aorta, however, PWV in the MPA is much less documented (5, 14), despite its potential importance in the screening of PAH. In addition to very early works employing either theoretical models of vascular trees (15) or highly invasive measurement techniques (16), only scarce reports are found in the literature (14, 17, 18). The lack of investigative studies on PWV in the MPA can be understood because a measurement of arterial PWV usually involves the determination of the transit time of the pressure pulse over a known distance (19), while the short length of the MPA (about 5 cm) (20) imposes a practical difficulty as it demands a high temporal resolution.…”

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confidence: 99%

Estimation of pulse wave velocity in main pulmonary artery with phase contrast MRI: Preliminary investigation

Peng¹,

Chung²,

Yu³

et al. 2006

Magnetic Resonance Imaging

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Purpose: To assess the feasibility and reproducibility of a noninvasive MRI method to measure pulse wave velocity (PWV) in the main pulmonary artery (MPA). Materials and Methods:A total of 17 subjects without history of pulmonary diseases (38.2 Ϯ 18.4 years) participated in this study. Series of MR velocity maps of the MPA were acquired at 2 cm above the pulmonary valves using a two-dimensional phase-contrast sequence. Effective temporal resolution was 11 msec after interleaving two dynamic series with different values of electrocardiograph (ECG) trigger delay. PWV was derived as the rate of MPA flow variations per unit change in MPA cross-sectional area, during early systole. Seven healthy subjects underwent three repetitive examinations to investigate intrascan and interscan reproducibility.Results: Flow vs. area was highly linear in the MPA during early systole, with Pearson's coefficients ranging from 0.982 to 0.999, rendering derivation of PWV with little difficulty. Average value of PWV in MPA was 1.96 Ϯ 0.27 m/second, in good agreement with literature values measured using invasive means. The percentage intra-and interscan differences were 5.46% and -10.86%, respectively. Conclusion:Phase-contrast MRI to noninvasively measure PWV in the MPA is feasible with good reproducibility.Key Words: pulse wave velocity; main pulmonary artery; phase contrast imaging; pulmonary arterial hypertension; noninvasive measurement.

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Pressure Wave Transmission in the Human Pulmonary Circulation

Cited by 22 publications

References 10 publications

Direct and series transmission of left atrial pressure perturbations to the pulmonary artery: a study using wave-intensity analysis

Direct and series transmission of left atrial pressure perturbations to the pulmonary artery: a study using wave-intensity analysis

Increased Pulmonary Venous Resistance in Morbidly Obese Patients without Daytime Hypoxia

Estimation of pulse wave velocity in main pulmonary artery with phase contrast MRI: Preliminary investigation

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