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Cardiovascular System:
Published in Michel R. Labrosse, Cardiovascular Mechanics, 2018
The heart is enclosed within the pericardium, a thin but tough connective tissue sheath. It provides protection and anchoring of the heart within the chest cavity, as well as acts as a constraint that prevents the overfilling of the heart chambers. The fluid within the pericardial sac gives the heart some lubrication as it contracts and moves within the space. The heart muscle is supplied with blood and oxygen by the coronary circulation (the right, the left anterior descending, and the left circumflex coronary arteries). During systole (or contraction), the vessels are compressed by the muscle, so most of the coronary flow (roughly 70%) must occur during diastole (or relaxation). If nutrient supply is insufficient (e.g., by an occluded coronary artery in ischemia), damage to the heart muscle can occur.
Miscellaneous application of chemometrics
Published in Madhusree Kundu, Palash Kumar Kundu, Seshu Kumar Damarla, Chemometric Monitoring: Product Quality Assessment, Process Fault Detection, and Applications, 2017
Madhusree Kundu, Palash Kumar Kundu, Seshu Kumar Damarla
The heart is considered to be one of the three most important body organs, along with the kidneys and the central nervous system, insofar as life support is concerned. The human heart is a four-chambered, hollow, and flexible organ that collects impure blood from the other organs, purifies it, and then circulates oxygenated blood to the whole body. It is placed in the thoracic chamber, anterior to the vertebral column and posterior to the sternum, slightly offset to the left. Depending on the age, it weighs between 250 and 350 g. The human heart consists of two pairs of atria and ventricles, longitudinally connected. The heart along with the network of veins (which carry deoxygenated blood) and arteries (which carry oxygenated blood) forms the cardiovascular system to supply blood to the whole body. The word cardiac is derived from Greek word kardia, meaning “related to the heart.” Details of the human heart physiology can be found in [1,2]. The atria receive the blood from the body, and ventricles supply the blood. The pair of atria and ventricles work in tandem, that is they contract and expand together to collect and supply blood, respectively. In between these two operations, there is an important function of purification, which is performed by sending the impure (deoxygenated) blood to the lungs. To achieve this, the right ventricle sends the impure blood to the lungs and receives the pure blood at the left atria. A complete cardiac cycle consists of collection of blood from body organs, purifying it, and sending it back to the whole body. The pumping action of the heart supports the following circulatory systems: Pulmonary circulation: This supports blood circulation to the lungs for purification.Systemic circulation: This supports blood circulation to the entire body except the lungs.Coronary circulation: Coronary circulation takes care of circulating oxygenated blood to the heart cells.
The role of cardiac computed tomography in pre-participation screening of mature athletes
Published in European Journal of Sport Science, 2022
Georgios A. Christou, Asterios P. Deligiannis, Evangelia J. Kouidi
Although there are some conflicting results, the majority of studies have suggested that mature athletes may have higher prevalence of coronary calcification and different composition of coronary plaques, which appear to be more calcified, compared to sedentary individuals (Aengevaeren et al., 2017; Jafar et al., 2019; Merghani et al., 2017; Mohlenkamp et al., 2008; Schwartz et al., 2014). However, firm conclusions about the impact of athletic activity on coronary lumen diameter cannot be inferred. Therefore, the coronary plaques of mature athletes are possibly more stable and less susceptible to rupture and thus less likely to be associated with an acute coronary event. In this respect, the clinical significance of coronary calcification in mature athletes could be overestimated and may be different from that of sedentary individuals. Consistently, at any given CACS level, higher level of physical activity was shown to be associated with decreased mortality, implying an overall health benefit of chronic exercise (DeFina et al., 2019). The differences in plaque morphology between athletes and sedentary individuals suggest that the pathophysiology of plaque formation and calcification in athletes may be different from that of nonathletic individuals. Potential mechanisms underlying the higher burden of coronary calcification in mature athletes include the shear stress-induced endothelial damage in the context of exercise-related hyperdynamic coronary circulation, coronary artery bending resulting from exercise-induced robust cardiac contractions, exercise-provoked coronary spasm and upregulation of parathyroid hormone secretion by exercise (Barry & Kohrt, 2007; Merghani et al., 2017). Based on the aforementioned considerations, it can be reasonably assumed that coronary calcification in athletes could protect against plaque rupture and may reflect less accurately the burden of atherosclerosis compared to sedentary individuals. Further studies are needed to elucidate these issues.
Device profile of the VEST for external support of SVG Coronary artery bypass grafting: historical development, current status, and future directions
Published in Expert Review of Medical Devices, 2021
An important observation was that the use of metallic clips (as opposed to sutures) to ligate saphenous vein branches during conduit preparation resulted in a reduced effectiveness on intimal hyperplasia most obvious in stented grafts to the right coronary circulation. The results of this pilot trial led to CE Mark approval in the European Union.