Sunday, November 3, 2019

Anesthetic Management of the Patient with Aortic Stenosis Essay

Anesthetic Management of the Patient with Aortic Stenosis - Essay Example Surgery is indicated in many of the cases in order to repair or replace the diseased valve. Therefore, it is the purpose of this paper to investigate the current anesthetic management of this disease, from preoperative to postoperative care. This paper will describe the basic anatomy and physiology of the heart, in particular, the aortic valve. The pathophysiological changes in the aortic valve and the heart will also be discussed. The heart is a hollow muscular organ that is somewhat pyramid-shaped and lies within the inferior mediastinum (3). It is covered by a fibroserous sac called the pericardium, within which pericardial fluid fills the space between the serous and fibrous layers. The pericardial fluid acts as a lubricant to prevent friction during the contraction of the heart. The pericardium is not very distensible, and therefore it strongly resists a large, rapid increase in cardiac size. Hence, the pericardium also prevents sudden overdistention of the chambers of the heart (4). The heart is divided by a vertical septa into four chambers: the right and left atria, which occupy the upper chambers and the right and left ventricles, which occupy the lower chambers. ... Although most myocardial cells are able to perform both these functions, the vast majority is predominantly contractile cells (myocytes) and a small number are specifically designed as electrical cells. The latter, collectively known as the conducting system of the heart, are not nervous tissue but modified myocytes lacking in myofibril components. They have the ability to generate electrical impulses which are then conducted to the myocytes, leading to contraction by a process known as excitation-contraction coupling (5). In order to produce a synchronized contraction, there must be a normal spread of electrical activity within the heart. Depolarization is initiated in the sinoatrial node (SA) node hence it is known as the pacemaker of the heart. It sets the contractions of the heart at a rate of 60-100 beats per minute. From the SA node, the electrical impulse travels to the atrioventricular (AV) node and then propagates through the Bundle of His. From the top of the septum, the wa ve of depolarization spreads in the rapidly conducting Purkinje fibers to all parts of the ventricles (6). Between the atria, ventricles and great blood vessels arising from the heart (aorta and pulmonary artery) are valves, which are made up of cusps or leaflets to prevent backflow of blood, ensuring a one-way conduit of blood through the chambers and to the pulmonary and systemic circulation. There are four valves: two semilunar valves (aortic and pulmonary valves) and two atrioventricular valves (tricuspid and mitral valves). All of these valves have 3 cusps except the mitral valve which has two cusps. Unoxygenated blood from the superior and inferior vena cava and coronary

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