The Left Atrial X Descent

Nixon, P.G.F.; Polis, O

doi:10.1136/hrt.24.2.173

Cited by 6 publications

(1 citation statement)

References 14 publications

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“…The rise in pressure observed with the c wave is a result of a BCW arising from LV contraction and the process of mitral valve closure, including the potential bulging of the leaflets into the LA. The decline in pressure is a result of a BDW generally attributed to the descent of the mitral annulus towards the apex during early systole and the effective increase of LA volume with a closed mitral valve (Nixon & Polis, 1962;Nolan et al 1969;Keren et al 1988).…”

Section: Genesis Of the A And C Wavesmentioning

confidence: 99%

Genesis of the characteristic pulmonary venous pressure waveform as described by the reservoir‐wave model

Bouwmeester

Belenkie

Shrive

et al. 2014

The Journal of Physiology

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Key pointsr In pressure flow data from a pulmonary vein, we use the reservoir wave model to separate the effects of an elastic venous reservoir from the effects of waves created by the heart. r Wave intensity analysis was used to separate the effects of waves generated upstream by the right ventricle from the effects of waves generated downstream by the left atrium and left ventricle.r Most waves are created by the left atrium and left ventricle and can be linked to events that occur during the cardiac cycle.r Waves transmitted through the pulmonary circulation are attenuated less when blood volume is increased but are attenuated more and delayed when the lungs are expanded.r The drainage of pulmonary arterial and venous reservoirs are responsible for substantial changes in measured pulmonary venous pressure and flow but waves are associated with the conventional landmarks of these characteristic waveforms.Abstract Conventional haemodynamic analysis of pulmonary venous and left atrial (LA) pressure waveforms yields substantial forward and backward waves throughout the cardiac cycle; the reservoir wave model provides an alternative analysis with minimal waves during diastole. Pressure and flow in a single pulmonary vein (PV) and the main pulmonary artery (PA) were measured in anaesthetized dogs and the effects of hypoxia and nitric oxide, volume loading, and positive-end expiratory pressure (PEEP) were observed. The reservoir wave model was used to determine the reservoir contribution to PV pressure and flow. Subtracting reservoir pressure and flow resulted in 'excess' quantities which were treated as wave-related. Wave intensity analysis of excess pressure and flow quantified the contributions of waves originating upstream (from the PA) and downstream (from the LA and/or left ventricle (LV)). Major features of the characteristic PV waveform are caused by sequential LA and LV contraction and relaxation creating backward compression (i.e. pressure-increasing) waves followed by decompression (i.e. pressure-decreasing) waves. Mitral valve opening is linked to a backwards decompression wave (i.e. diastolic suction). During late systole and early diastole, forward waves originating in the PA are significant. These waves were attenuated less with volume loading and delayed with PEEP. The reservoir wave model shows that the forward and backward waves are negligible during LV diastasis and that the changes in pressure and flow can be accounted for by the discharge of upstream reservoirs. In sharp contrast, conventional analysis posits forward and backward waves such that much of the energy of the forward wave is opposed by the backward wave.

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Section: Genesis Of the A And C Wavesmentioning

confidence: 99%