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The Systemic Circulation
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
In essence, the elastic nature of the aorta allows it to work as a second pump in series with the ventricle during diastole. The Windkessel effect reduces the cardiac workload, as excess work must be done to pump a given flow intermittently rather than continuously. One consequence of the loss of arterial elasticity with age is that this aortic hydraulic filter becomes less effective.
Aortic and Arterial Mechanics
Published in Michel R. Labrosse, Cardiovascular Mechanics, 2018
The heart acts as a pulsatile pump that propels blood into the vascular system during its contraction (systole). Part of the blood ejected during systole is stored during distension of the aorta and the proximal arteries. The function of the large elastic arteries is to relay the contraction of the heart when it enters its relaxation phase (diastole), thanks to their compliance. After closing the aortic valve, the aorta and the proximal arteries retract elastically and restore the volume of blood stored. This is the Windkessel effect, by which blood pressure is maintained and blood flow is increased in diastole, which ensure a continuous and nonpulsatile flow in the peripheral arteries and the capillaries. This function of diastolic relay of the cardiac contraction is directly related to the elastic properties of the large arteries, which are conferred on them by the large quantity of elastic fibers and type III collagen in the media [1,2].
Haemodynamics: flow, pressure and resistance
Published in Neil Herring, David J. Paterson, Levick's Introduction to Cardiovascular Physiology, 2018
Neil Herring, David J. Paterson
The ventricle ejects blood into the proximal elastic arteries, namely the aorta and subclavian vessels, faster than the blood can drain away. The resulting expansion of these elastin-rich vessels causes a steep increase in arterial pressure during systole (Figures 8.7 and 8.8). Around 67%-80% of the stroke volume is temporarily stored in the elastic arteries during systole, while 20%-33% runs off through the peripheral resistance. The mechanical energy stored in the stretched elastin serves to maintain the blood pressure during diastole (known as the Windkessel effect).
Artificial intelligence measuring the aortic diameter assist in identifying adverse blood pressure status including masked hypertension
Published in Postgraduate Medicine, 2022
Yaoling Wang, Lijuan Bai, Jinrong Yang, Yichen Lu, Wenliang Fan, Zhuang Nie, Jie Yu, Kai Wen, Ruiyun Wang, Linfeng He, Fan Yang, Benling Qi
In our description of the relationship between BP and the AD, the true change did not show a single linear growth relationship: at a lower BP level, the AD decreases as the BP level increases, which may be the arterial lumen adapt to the performance of blood perfusion. The blood vessels function well, and the arteries contract to maintain or reach the optimal BP state, which is in line with the best Windkessel effect, under excessively high BP levels, blood vessels are remodeled significantly during the process of increasing BP, and the arteries are adaptively expanded, and the arterial stiffness has reached its peak. The reduction of AD at this time was the result of the balance of the increasing pulse pressure under the increase of the arterial stiffness, and it is also the performance of coping with BP decompensation [16].
Elevated levels of short-term blood pressure variability: A marker for ascending aortic dilatation in hypertensive patients
Published in Clinical and Experimental Hypertension, 2021
Onur Argan, Eyup Avci, Serdar Bozyel, Tarik Yildirim, Ozgen Safak, Seda Elcim Yildirim, Ahmet Dolapoglu, Halil Lutfi Kisacik
The association between AAD and higher LVM as an indicator of LVH has been demonstrated before and studies highlighted a positive association between AAD and LVH in HT patients. Milan et al. demonstrated AAD being a marker related to increased LVH and LVM (34). Furthermore, in another study, Milan et al. reported that LVM was associated with AAD in HT patients (35). Karatas et al. reported that LVMI values were positively correlated with ASI (33). Similarly, in multivariate regression analysis, we indicated that LVMI was independently associated with ASI. The effect of LVH on AA may be clarified by the proximal aorta being more directly exposed to the higher stroke volume accompanying higher left ventricle mass. Therefore, an increase in the AA size is observed owing to the “Windkessel effect.”
The Rise of Endovascular Mechanical Circulatory Support Use for Cardiogenic Shock and High Risk Coronary Intervention: Considerations and Challenges
Published in Expert Review of Cardiovascular Therapy, 2021
Benjamin Schwartz, Pankaj Jain, Michael Salama, Navin K. Kapur
The utility of IABP was first described in 1968 around the idea of diastolic augmentation and counterpulsation and was initially used for cardiogenic shock [3]. Since then, applications have diversified as the device mechanics and technology evolved. The modern IABP is a catheter-mounted balloon, deployed through arterial access, which augments pulsatile flow by inflating during diastole. The IABP is coupled with the electrocardiogram, arterial line pressure, and fiber-optic sensors so as to sync with systole and diastole [4]. The two phases offer distinct advantages. Inflating the balloon during diastole, synchronously with aortic valve closure, displaces blood volume in the descending aorta, where the balloon sits, and increases mean aortic pressure, consequently improving end organ and coronary perfusion [2,5]. During systole, while deflated, the post-aortic valve pressure drops precipitously, decreasing afterload, left ventricular wall stress, myocardial oxygen demand, and augmenting ventricular stroke volume [2,6]. The afterload reducing mechanism, known as the Windkessel effect, provides up to a 10–20% increase in cardiac output; however, the diastolic phase has variable success in hemodynamic improvement and may depend on the clinical scenario [4,7].