Pulmonary artery wave propagation and reservoir function in conscious man: impact of pulmonary vascular disease, respiration and dynamic stress tests

Su, Junjing; Manisty, Charlotte; Simonsen, Ulf; Howard, Luke; Parker, Kim H.; Hughes, Alun D.

doi:10.1113/jp274385

Cited by 12 publications

(15 citation statements)

References 49 publications

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“…Sundblad et al [52], who studied subjects during rest and leg exercise, as they were suddenly tilted from upright to supine, found an initial drop in SV, which they attributed to ventricular interdependence [15,[50][51][52]. Moreover, pulmonary circulation, a remarkable blood reservoir, may act as a buffer [53], further attenuating the effect of venous return on left ventricular contraction. On the other hand, Elstad et al [43], who performed exercise with small proximal muscle masses, stressed the role of muscle vasodilation and the ensuing rapid TPR fall in determining the φ1 increase in SV.…”

Section: Discussionmentioning

confidence: 99%

Effect of Lower Body Negative Pressure on Phase I Cardiovascular Responses at Exercise Onset

et al. 2020

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We hypothesised that vagal withdrawal and increased venous return interact in determining the rapid cardiac output (CO) response (phase I) at exercise onset. We used lower body negative pressure (LBNP) to increase blood distribution to the heart by muscle pump action and reduce resting vagal activity. We expected a larger increase in stroke volume (SV) and smaller for heart rate (HR) at progressively stronger LBNP levels, therefore CO response would remain unchanged. To this aim ten young, healthy males performed a 50 W exercise in supine position at 0 (Control), −15, −30 and −45 mmHg LBNP exposure. On single beat basis, we measured HR, SV, and CO. Oxygen uptake was measured breath-by-breath. Phase I response amplitudes were obtained applying an exponential model. LBNP increased SV response amplitude threefold from Control to −45 mmHg. HR response amplitude tended to decrease and prevented changes in CO response. The rapid response of CO explained that of oxygen uptake. The rapid SV kinetics at exercise onset is compatible with an increased venous return, whereas the vagal withdrawal conjecture cannot be dismissed for HR. The rapid CO response may indeed be the result of two independent yet parallel mechanisms, one acting on SV, the other on HR.

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Section: Discussionmentioning

confidence: 99%

Effect of Lower Body Negative Pressure on Phase I Cardiovascular Responses at Exercise Onset

et al. 2020

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“…Wave intensity is positive for forward‐traveling waves and negative for backward‐traveling waves. WIA was performed essentially as described previously, but values were normalized to cardiac cycle length to make it independent of sampling rate . With the knowledge of the local wave speed, waves were separated into their forward (shown as WI + ) and backward (shown as WI − ) components (Equation ):

{WI}_{\pm} = \pm {()(\frac{dP \cdot CCD}{dt} \pm ρ c \cdot \frac{dU \cdot CCD}{dt})}^{2} / false(4 normalρ normalc false)

…”

Section: Methodsmentioning

confidence: 99%

“…WIA was performed essentially as described previously, 2 but values were normalized to cardiac cycle length to make it independent of sampling rate. 20 With the knowledge of the local wave speed, waves were separated into their forward (shown as WI + ) and backward (shown as WI À ) components (Equation 6):…”

Section: Wave Intensity Analysismentioning

confidence: 99%

Wave Intensity Analysis Provides Novel Insights Into Pulmonary Arterial Hypertension and Chronic Thromboembolic Pulmonary Hypertension

Manisty

Parker

et al. 2017

JAHA

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BackgroundIn contrast to systemic hypertension, the significance of arterial waves in pulmonary hypertension (PH) is not well understood. We hypothesized that arterial wave energy and wave reflection are augmented in PH and that wave behavior differs between patients with pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH).Methods and ResultsRight heart catheterization was performed using a pressure and Doppler flow sensor–tipped catheter to obtain simultaneous pressure and flow velocity measurements in the pulmonary artery. Wave intensity analysis was subsequently applied to the acquired data. Ten control participants, 11 patients with PAH, and 10 patients with CTEPH were studied. Wave speed and wave power were significantly greater in PH patients compared with controls, indicating increased arterial stiffness and right ventricular work, respectively. The ratio of wave power to mean right ventricular power was lower in PAH patients than CTEPH patients and controls. Wave reflection index in PH patients (PAH: ≈25%; CTEPH: ≈30%) was significantly greater compared with controls (≈4%), indicating downstream vascular impedance mismatch. Although wave speed was significantly correlated to disease severity, wave reflection indexes of patients with mildly and severely elevated pulmonary pressures were similar.ConclusionsWave reflection in the pulmonary artery increased in PH and was unrelated to severity, suggesting that vascular impedance mismatch occurs early in the development of pulmonary vascular disease. The lower wave power fraction in PAH compared with CTEPH indicates differences in the intrinsic and/or extrinsic ventricular load between the 2 diseases.

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“…5 ) was normalized to the number of samples squared in the cardiac cycle and separated into its forward (WI + ) and backward (WI − ) components ( Eq. 6 ) ( 58 ). The measured pressure was separated into forward (P f ) and backward (P b ) pressure waveforms by integrating the differentials, dP f and dP b ( Eq.…”

Section: Methodsmentioning

confidence: 99%

Impact of chronic hypoxia on proximal pulmonary artery wave propagation and mechanical properties in rats

Logan

Hughes

et al. 2018

American Journal of Physiology-Heart and Circulatory Physiology

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Arterial stiffness and wave reflection are important components of the ventricular afterload. Therefore, we aimed to assess the arterial wave characteristics and mechanical properties of the proximal pulmonary arteries (PAs) in the hypoxic pulmonary hypertensive rat model. After 21 days in normoxic or hypoxic chambers (24 animals/group), animals underwent transthoracic echocardiography and PA catheterization with a dual-tipped pressure and Doppler flow sensor wire. Wave intensity analysis was performed. Artery rings obtained from the pulmonary trunk, right and left PAs, and aorta were subjected to a tensile test to rupture. Collagen and elastin content were determined. In hypoxic rats, proximal PA wall thickness, collagen content, tensile strength per unit collagen, maximal elastic modulus, and wall viscosity increased, whereas the elastin-to-collagen ratio and arterial distensibility decreased. Arterial pulse wave velocity was also increased, and the increase was more prominent in vivo than ex vivo. Wave intensity was similar in hypoxic and normoxic animals with negligible wave reflection. In contrast, the aortic maximal elastic modulus remained unchanged, whereas wall viscosity decreased. In conclusion, there was no evidence of altered arterial wave propagation in proximal PAs of hypoxic rats while the extracellular matrix protein composition was altered and collagen tensile strength increased. This was accompanied by altered mechanical properties in vivo and ex vivo.NEW & NOTEWORTHY In rats exposed to chronic hypoxia, we have shown that pulse wave velocity in the proximal pulmonary arteries increased and pressure dependence of the pulse wave velocity was steeper in vivo than ex vivo leading to a more prominent increase in vivo.

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Pulmonary artery wave propagation and reservoir function in conscious man: impact of pulmonary vascular disease, respiration and dynamic stress tests

Cited by 12 publications

References 49 publications

Effect of Lower Body Negative Pressure on Phase I Cardiovascular Responses at Exercise Onset

Effect of Lower Body Negative Pressure on Phase I Cardiovascular Responses at Exercise Onset

Wave Intensity Analysis Provides Novel Insights Into Pulmonary Arterial Hypertension and Chronic Thromboembolic Pulmonary Hypertension

Impact of chronic hypoxia on proximal pulmonary artery wave propagation and mechanical properties in rats

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