Is the time constant of the pulmonary circulation truly constant?

Grignola, Juan C.

doi:10.1183/09031936.00158113

Cited by 3 publications

(2 citation statements)

References 10 publications

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“…A constant RC-time product has important implications for the assessment of RV afterload, namely that PVR and total arterial compliance are redundant measurements and knowledge of one enables the derivation of the other. Exceptions to the constant RC-time product have recently been documented, for example in PH-related to left heart disease [22][23][24][25], prompting a re-evaluation of the concept of RC-time constancy [26][27][28][29].…”

Section: Introductionmentioning

confidence: 99%

Pulmonary vascular resistance and compliance relationship in pulmonary hypertension

et al. 2015

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Right ventricular adaptation to the increased pulmonary arterial load is a key determinant of outcomes in pulmonary hypertension (PH). Pulmonary vascular resistance (PVR) and total arterial compliance (C) quantify resistive and elastic properties of pulmonary arteries that modulate the steady and pulsatile components of pulmonary arterial load, respectively. PVR is commonly calculated as transpulmonary pressure gradient over pulmonary flow and total arterial compliance as stroke volume over pulmonary arterial pulse pressure (SV/PApp). Assuming that there is an inverse, hyperbolic relationship between PVR and C, recent studies have popularised the concept that their product (RC-time of the pulmonary circulation, in seconds) is "constant" in health and diseases. However, emerging evidence suggests that this concept should be challenged, with shortened RC-times documented in post-capillary PH and normotensive subjects. Furthermore, reported RC-times in the literature have consistently demonstrated significant scatter around the mean. In precapillary PH, the true PVR can be overestimated if one uses the standard PVR equation because the zero-flow pressure may be significantly higher than pulmonary arterial wedge pressure. Furthermore, SV/PApp may also overestimate true C. Further studies are needed to clarify some of the inconsistencies of pulmonary RC-time, as this has major implications for our understanding of the arterial load in diseases of the pulmonary circulation. @ERSpublications Empiric estimates of pulmonary arterial load are prone to errors and may result in overestimation of RC-time

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Section: Introductionmentioning

confidence: 99%

Pulmonary vascular resistance and compliance relationship in pulmonary hypertension

et al. 2015

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“…We estimated pulmonary arterial RC time as the product of resistance and capacitance (PVR × Cp). We examined the relationship between TPR and Cp to analyze the consequences of pulmonary vascular disease to the dynamic afterload [19]. To compare the TPR-Cp relationship for each group, the TPR, and Cp data were logarithmically transformed and plotted on a linear axis.…”

Section: Methodsmentioning

confidence: 99%

Pulmonary arterial wall disease in COPD and interstitial lung diseases candidates for lung transplantation

et al. 2017

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BackgroundPulmonary hypertension (PH) associated with lung disease has the worst prognosis of all types of PH. Pulmonary arterial vasculopathy is an early event in the natural history of chronic obstructive pulmonary disease (COPD) and interstitial lung disease (ILD). The present study characterized the alterations in the structure and function of the pulmonary arterial (PA) wall of COPD and ILD candidates for lung transplantation (LTx).MethodsA cohort of 73 patients, 63 pre-LTx (30 COPD, 33 ILD), and ten controls underwent simultaneous right heart catheterisation and intravascular ultrasound (IVUS). Total pulmonary resistance (TPR), capacitance (Cp), and the TPR-Cp relationship were assessed. PA stiffness and the relative area of wall thickness were estimated as pulse PA pressure/IVUS pulsatility and as [(external sectional area-intimal area)/external sectional area] × 100, respectively.ResultsTwenty-seven percent of patients had pulmonary arterial wedge pressure > 15 mmHg and were not analyzed. PA stiffness and the area of wall thickness were increased in comparison with controls, even in patients without PH (p < 0.05). ILD patients showed a significant higher PA stiffness, and lower Cp beyond mean PA pressure (mPAP) and lower area of wall thickness than COPD patients (p < 0.05). TPR-Cp relationship was shifted downward left for ILD patients.ConclusionsSignificant increase of PA stiffness and area of wall thickness were present even in patients without PH and can make the diagnosis of pulmonary vasculopathy at a preclinical stage in PH-lung disease candidates for LTx. ILD patients showed the worst PA stiffness and Cp with respect to COPD.

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Conceptos básicos en circulación pulmonar

Grignola

Domingo

2017

Revista Colombiana de Cardiología

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Is the time constant of the pulmonary circulation truly constant?

Cited by 3 publications

References 10 publications

Pulmonary vascular resistance and compliance relationship in pulmonary hypertension

Pulmonary vascular resistance and compliance relationship in pulmonary hypertension

Pulmonary arterial wall disease in COPD and interstitial lung diseases candidates for lung transplantation

Conceptos básicos en circulación pulmonar

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