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Cardiovascular Disease
Published in John S. Axford, Chris A. O'Callaghan, Medicine for Finals and Beyond, 2023
Shortness of breath is a predominant symptom associated with fatigue because of poor cardiac output. The elevated venous pressure on the right side gives rise to peripheral oedema, ascites and an enlarged liver, which can be painful. Signs include tachycardia, raised venous pressure with Kussmaul's sign (an increase in venous pressure on inspiration) and third and fourth heart sounds.
Anesthesia Monitoring and Management
Published in Michele Barletta, Jane Quandt, Rachel Reed, Equine Anesthesia and Pain Management, 2023
Arterial blood pressure is directly correlated with cardiac output. Blood pressure can be measured indirectly (noninvasively) using Doppler or oscillometric methods or directly (invasively) by arterial catheterization.
General Principles for Measuring Arterial Waves
Published in Wilmer W Nichols, Michael F O'Rourke, Elazer R Edelman, Charalambos Vlachopoulos, McDonald's Blood Flow in Arteries, 2022
Methods that measure cardiac output (CO) and stroke volume (SV) can be separated into those that measure CO continuously and calculate SV as the quotient of CO and heart rate (HR) and those that measure SV and calculate CO as the product of SV and HR. In this section we first describe the methods that calculate CO continuously and then those that measure stroke volume.
Cardiovascular responses to hot skin at rest and during exercise
Published in Temperature, 2023
Ting-Heng Chou, Edward F. Coyle
Maintained stroke volume and increased heart rate allow a large increase in cardiac output [5,65,66,93] when the skin vasculature is dilated and no muscle pump is active at rest. Mean arterial blood pressure is usually maintained or only slightly decreased [57,59,94]. Maintained blood pressure is partially achieved by an increase in cardiac output. In addition to an increase in cardiac output, other vascular beds also make adjustments to passive heat stress. For example, splanchnic blood flow reduces by about 40% [55–59,61,66,95,96], and renal blood flow decreases by 15–40% during passive heating [58,66,97,98]. The decrease in splanchnic and renal blood flow can be caused by reducing perfusion pressure as arterial blood pressure sometimes slightly decreases during passive heat stress [57,99], and by sympathetically mediated vasoconstriction as splanchnic vascular resistance increases during passive heat stress (Figure 8) [58,59]. Vasoconstriction of splanchnic and renal vascular beds helps maintain mean arterial blood pressure and reduces the distending pressure of the highly compliant vasculature, which results in a reduction in blood volume in those regions. Reductions in splanchnic blood volume during heat stress have been qualitatively assessed from x-ray dimensions of the liver, showing reduced volume [100]. Crandall et al. [71,101] also observed that liver and spleen blood volumes are reduced during passive heat stress. Therefore, blood redistributes from visceral organs to the skin during passive heat stress.
Common systemic medications that every optometrist should know
Published in Clinical and Experimental Optometry, 2022
Hypertension is defined as sustained elevation of resting systolic blood pressure (≥ 130 mmHg), diastolic blood pressure (≥ 80 mmHg), or both. Hypertension is a common and important risk factor for cardiovascular and renal diseases. In 2017, an estimated 4.1 million working-age Australians (25.9%) had hypertension, of whom an estimated 21.6% were treated and controlled, 17% were treated but uncontrolled, and 61.4% were untreated.6 The pathogenesis of hypertension is multifactorial and complex. The most common blood pressure medications are angiotensin-converting enzyme (ACE) inhibitors, calcium channel blockers, beta blockers, and diuretics. However, many patients use more than one class of medication to adequately control their hypertension. Vasodilators such as ACE inhibitors and calcium channel blockers aim to reduce blood pressure through vessel dilation. Beta blockers reduce cardiac output by reducing sympathetic influences. Diuretics are effective in reducing blood volume and cardiac output by increasing urine output from the kidneys.7
The Clinical Implications of Body Surface Area as a Poor Proxy for Cardiac Output
Published in Structural Heart, 2021
Michiel D. Vriesendorp, Rolf H.H. Groenwold, Howard C. Herrmann, Stuart J. Head, Rob A.F. De Lind Van Wijngaarden, Pieter A. Vriesendorp, A. Pieter Kappetein, Robert J.M. Klautz
A search for a better criterion for PPM that is predictive of clinical status should abandon anthropometric measures for the indexation of EOA. While there is a weak association between body size and cardiac output, and therefore the required valve size, cardiac output is also influenced by many other factors (e.g. genetics, lifestyle, etc.). Instead of finding new proxies of normal cardiac output to index EOA, an alternative is to use hemodynamic parameters that are independent of cardiac output for a new definition of PPM, e.g. Doppler velocity index. As calculation of this index does not require BSA and the LVOT diameter,19 Doppler velocity index is not only easier to calculate than EOAi, but it is potentially also a more reliable measurement of hemodynamic obstruction. Further research needs to focus on Doppler velocity index as a predictor of clinical events related to hemodynamic obstruction after AVR.