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Contour of Pressure and Flow Waves in Arteries
Published in Wilmer W Nichols, Michael F O'Rourke, Elazer R Edelman, Charalambos Vlachopoulos, McDonald's Blood Flow in Arteries, 2022
Use of arterial tonometry (Avolio et al., 1988; Kelly et al., 1988a, 1988b; Saba et al., 1993; Vaitkevicius et al., 1993; London et al., 1995; Chen et al., 1996, 1997) has provided fresh information on pressure wave transmission to the upper limbs in humans and indeed fresh insight into the effects of aging and of vasoactive drugs on the arterial pressure wave (O'Rourke, 1988; Kelly et al., 1989a, 1989b; O'Rourke et al., 1989a, 1989b, 1992a, 1992b, 1993a; O'Rourke and Kelly, 1993; Adji et al., 2016). This is discussed later (see Chapter 27) and has important implications for interpretation of sphygmomanometric pressures with different therapies in humans (O'Rourke, 1990a; O'Rourke et al., 1993a; Chen et al., 1996, 1997; Williams et al., 2006; Miyashita et al., 2010; Ong et al., 2011; Levi-Marpillat et al., 2014). A full chapter (Chapter 25) is devoted to the concept of central aortic pressure that arises from this.
Fetal and neonatal medicine
Published in Jagdish M. Gupta, John Beveridge, MCQs in Paediatrics, 2020
Jagdish M. Gupta, John Beveridge
4.36. In the fetal circulationthere is right-to-left shunting at atrial level.there is left-to-right shunting at ductal level.the pulmonary artery pressure is lower than the aortic pressure.oxygen saturation of the blood entering the fetal lung is lower than that of blood entering the aorta.persistence of blood flow through ductus arteriosus after delivery can be abolished by prostaglandin synthetase inhibitors.
Functions of the Cardiovascular System
Published in Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal, Principles of Physiology for the Anaesthetist, 2020
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal
The driving pressure in the coronary circulation is aortic pressure, but this is affected by extravascular compression of vessels during ventricular contraction. This is especially important in the left ventricle: in early systole, blood flow in the vessels is reversed, and most of the flow to the left ventricle takes place during diastole. This effect is less important in the right ventricle, as the pressure developed by contraction (25 mmHg) is much lower. In diastole, there is no compression of coronary vessels. Coronary blood flow to the left ventricle is intermittent, being maximal in diastole but stopping in early systole. In contrast, right ventricular coronary blood flow is pulsatile and is slightly higher during systole. Systolic compression of the coronary vessels is greater in the endocardium of the left ventricular wall than in the epicardium. Normally, the lack of blood flow in the left ventricle wall during systole is made up by the high flow during diastole (Figure 23.5).
Central arterial pressure and patient-specific model parameter estimation based on radial pressure measurements
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2023
Dániel Gyürki, Tamás Horváth, Sára Till, Attila Egri, Csilla Celeng, György Paál, Béla Merkely, Pál Maurovich-Horvat, Gábor Halász
In this method, the pressure is known at the periphery (e.g. the radial or the carotid artery). The first step is to perform an original (forward in time) simulation on the subgraph distal to the point whose pressure is known, to acquire the velocity of that point as well. The second step is to calculate one segment backwards, towards the heart. In this step the characteristic lines run from the distal end of the vessel, opposite to the pulse wave propagation, in contrast to the original method of characteristics, where the lines march forward in time. The velocity, pressure and the deformation values are calculated at the intersection points of these lines. When the backward marching characteristic lines reach the starting node of the segment, another forward simulation is performed on the new subgraph, to acquire the velocities of the other segments of that junction. Then a new backward marching is started from that point, repeating these steps. The march from the periphery is continued until the characteristic lines reach the heart. Therefore, the aortic pressure curve is calculated from the peripheral pressure measurement. The authors tested their method on a model arterial network and achieved high accuracy. Our research is based on this method, and is referred to later as backward calculation.
FFR pressure wire comparative study: piezoresistive versus optical sensor
Published in Acta Cardiologica, 2022
Daan Cottens, Joren Maeremans, Mathias Vrolix, Johan Van Lierde, Jo Dens, Bert Ferdinande
Pressure drift (PD) is, even with the impressive technical developments over the last 20 years, still a common phenomenon. It is often defined as a mean aortic pressure minus mean distal pressure measured after pullback at the tip of the guiding of >3mmHg, which is equivalent with a Pd/Pa ratio after pullback different from 1.0 ± 0.02. A recent large study with the piezoresistive pressure sensor Pressure Wire Certus reported a significant drift phenomenon (≥4 mmHg) in 11,8% of the cases and a small drift (PD ≤ 3 mmHg) frequency in 39,3% of the cases [8]. It is generally accepted that a PD > 4 mmHg makes a re-measurement mandatory. The phenomenon of small drift does not have a significant impact: it does not changes the decision when FFR value is <0,76 or >0,82, it only changes for the FFR in between the classification in 18,7% of the cases but not in a single patient did the value shift from above the upper limit of the grey zone (0,76-0,80) to below the lower limit or vice versa [8]. The small PD phenomenon does have a more important impact when you measure resting gradients, because the signal to noise ratio during hyperaemia is 2.5 to 3.0-fold higher compared to resting gradients. As a consequence, it can be expected to be more vulnerable to the influence of drift [9].
Prognostic value of main pulmonary artery diameter to ascending aorta diameter ratio in patients with advanced heart failure
Published in Acta Cardiologica, 2021
Cem Dogan, Zubeyde Bayram, Süleyman Cagan Efe, Rezzan Deniz Acar, Ibrahim Halil Tanboga, Ali Karagoz, Nuri Havan, Tanıl Ozer, Abdulkair Uslu, Mehmet Kaan Kırali, Cihangir Kaymaz, Nihal Ozdemir
We performed right and left heart catheterisation with 6 French pigtail catheters under the guidance of fluoroscopy. Aortic pressure (AoP), pulmonary arterial systolic, mean, diastolic pressures (PAPs, PAPm, PAPd), right and left ventricular end-systolic, end-diastolic pressures (RVESP, LVESP, RVEDP, LVEDP) and right atrial pressure (RAP) were recorded. Cardiac output (CO), cardiac index (CI), stroke volume (SV), stroke volume index (SVI) were also calculated using the Fick method. Trans-pulmonary gradient (TPG: PAPm-LVEDP), trans-systemic gradient (TSG: mean AoP-RAP), pulmonary vascular resistance (PVR: TPG/CO), right ventricular stroke work index (RVSWI: PAPm-RAP × SVI × 0.0136) were calculated accordingly. The pulmonary hypertension (PH) was defined as PAPm ≥25 mmHg assessed by RHC [7].