Aortic stenosis

Aortic stenosis

Aortic stenosis is a valve disease, which is the narrowing of the aortic valve opening. Through the narrowing, it affects the flow of blood from the left ventricle to the aorta, which result in reduced pressure in the left atrium. The disease is rare in people below the age of 50 years (Cary & Pearce, 2013). For the few cases which happen in young people mostly, the disease is a result of birth heart defect where two valves grow instead of the usual three. Also, when the valve opening does not grow with the heart, it makes it hard for the heart to pump blood resulting in the thickening of the heart muscles. The symptoms of the aortic stenosis include breathlessness, chest pain, fainting, heart murmur, bulky and noticeable heartbeats, and decline in activity (Rauen, 2016). Due to the reduced pressure in the left atrium, it leads to the thickening of muscles since it requires to pump blood through the narrow opening. As the muscles thicken, they take up some space in the heart, thereby making the heart to hold less blood to be supplied throughout the body.

Pathophysiology

Under healthy heart and valve function, the aortic valve which one of the four valves separating the chambers of the heart open and close easily with the response of pressure during systole and diastole (Cary & Pearce, 2013). That ensures the forward progression of the blood to all parts of the body. An increase in the forward pressure causes the opening of the valve while a backward force closes it. The aortic valve separates the left ventricle and the aorta, and they open easily during the systole to allow blood out of the left ventricle into the aorta and then closes. The valve has leaflets that have three layers that contribute to its function. Each layer contains valvular interstitial cells that maintain the structure and function and help in the repair of cellular damage. Further, the pressure is equally distributed in the leaflet surface for closing and opening.

As the pressure increase, it also leads to mild thickening of the aortic valve’s leaflets. The progression of the disease increases the thickness of the leaflets, and the calcium modes form, which leads to the joining of the edge of the valves (Cary & Pearce, 2013). The calcium nodules formed bulge outside, joining with the sinuses, and preventing the opening of the leaflet. Therefore, the blood fails to get out of the left ventricle normally unless more pressure is applied. When the aortic valve becomes stenotic, there is resistance in the systolic ejection of blood from the left ventricle, which results to increase in pressure gradient between the aorta and the ventricle. The obstruction increases the systolic pressure in the left ventricle (Michail et al., 2018). Due to the increased pressure, the walls of the left ventricle respond by thickening the walls through parallel replication of sarcomeres. At such a stage, the chamber is not dilated, and the ventricle functions are not preserved. Another notable change at this level is that the diastolic compliance is also reduced. The progression of stenosis increases the obstruction of blood flow from the left ventricle to the aorta, which may take many years. Finally, through the increased obstruction of blood flow, the left ventricle end-diastolic pressure rises and causes pulmonary capillary arterial pressure, and cardiac output decreases (Michail et al., 2018). The thickening of the ventricle walls reduces the contractility of the myocardium, thereby decreasing the cardiac output as a result of systolic dysfunction.

Diagnosing

The doctor starts by reviewing the signs and symptoms, then discuss medical history and use a physical examination. It begins by listening to the heart to determine if there are heart murmur, which is one of the signs of aortic stenosis. To assess the severity of the condition, several tests are done. First, the echocardiogram test uses the sound waves to take a video of the heart and the motion. This aims to check the blood flow through the heart. An electrocardiogram measures the electrical activity of the heart and can detect enlarged chambers and notice any abnormal heart rhythms. A chest x-ray can be conducted to determine whether the heart is enlarged, which can occur due to the condition. Exercise tests include the doctor engaging the patient in a physical activity to see whether they exhibit the signs and symptoms of aortic valve disease. Also, a cardiac catheterization test is used when other tests are not able to diagnose the condition. The doctor threads a thin tube in the arm and guides it in an artery in your heart. It gives a detailed picture of the arteries and the functions of the heart. Also, it measures the pressure inside the heart chambers and can accurately detect aortic stenosis.

Clinical Manifestation

The clinical manifestation of angina, syncope, and heart failure does not occur until the aortic stenosis is in the late stage. Syncope occurs when there is decreased cerebral perfusion associated with a decrease in cardiac output. The usual exercise response does not happen to the patient with aortic stenosis condition. The narrowed aortic valve orifice limits the augmented stroke volume, which counterbalances the decrease in systematic vascular resistance. (Minamino-Muta et al., 2018). Besides, the signs and symptoms of heart failure include paroxysmal, dyspnea, orthopnea, and congestion in the pulmonary. These symptoms occur when blood flow encounter high diastolic pressure in the left ventricle. The delayed myocardial relaxation decreases the filling time, thereby reducing the volume of blood required to provide the distending pressure requirement in the left ventricle (Minamino-Muta et al., 2018). The palpation of the carotid artery and auscultation of heart sound give valuable insight in a patient with aortic stenosis. Also, the turbulent flow of blood can be heard as the systolic ejection murmurs with severely they increase the sound intensity.

Risk factors

As mentioned earlier, the disease is more prevalent in old age since only 1 out of 10 of the patients is below 50 years. The old age increases the risk factor for the condition. Also, some of the heart conditions that are present at birth, such as bicuspid aortic valve can lead to the disease among the younger population (Yan et al., 2017). History of infections that affect the heart can change the leaflet valve and inability to freely open and close, causing the aortic valve stenosis. More importantly, conditions like diabetes, high cholesterol, and high blood pressure increase the risk (Yan et al., 2017). Also, kidney disease and history of radiation therapy to the chest increase the risk of developing aortic stenosis.

Nursing Intervention

Caring for a patient with aortic stenosis requires that nurses understand preload and afterload to maintain the blood flow and adequate cardiac output. Hemodynamic considerations are weighed after nurses respond to signs and symptoms. Orthostatic hypotension may occur when patients are standing and sitting or after administration of nitrates. So, the nurses intervene with the goals of balancing rest and activity to maintain oxygen supply and maintain the required heart rate. Key objectives performed by the nurses in the prevention of deteriorating in clinical status and prevention of new signs and symptoms (Cary & Pearce, 2013).

Conclusion

The aortic stenosis condition that narrows the aortic valve opening leading to low blood volume being ejected from the heart. It is more prevalent in older people. The situation arises when the aorta valve leaflets fail to open freely, thereby requiring more pressure to pump blood through to the aorta. As a result, it leads to the thickening of the walls, which leads to holding low blood vole. The risk factors include older age, people with heart conditions, diabetes, high blood pressure, and high cholesterol. In young people with heart problems like a bicuspid valve, people who previously had an infection that affected the heart. The disease is diagnosed using several tests that focus on looking at the severity. The nursing intervention aims to prevent new signs and to ensure the patient balance rest and activity.

References

Cary, T. & Pearce J. ( 2013).Aortic Stenosis: Pathophysiology, Diagnosis, and Medical Management of Nonsurgical Patients. http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.832.2600&rep=rep1&type=pdf

Rauen, C., Jeffries, K., Makic, M. B. F., Alspach, J., Burns, S. M., Burns, S. M., … & Burns, S. M. (2016). Aortic stenosis: Pathophysiology, diagnosis, and medical management of nonsurgical patients. Critical care nurse, 36(2), 74-77.

Minamino-Muta, E., Kato, T., Morimoto, T., Taniguchi, T., Nakatsuma, K., Kimura, Y., … & Kitai, T. (2018). Malignant disease as a comorbidity in patients with severe aortic stenosis: clinical presentation, outcomes, and management. European Heart Journal-Quality of Care and Clinical Outcomes, 4(3), 180-188.

Michail, M., Davies, J. E., Cameron, J. D., Parker, K. H., & Brown, A. J. (2018). Pathophysiological coronary and microcirculatory flow alterations in aortic stenosis. Nature Reviews Cardiology, 15(7), 420-431.

Yan, A. T., Koh, M., Chan, K. K., Guo, H., Alter, D. A., Austin, P. C., … & Ko, D. T. (2017). Association between cardiovascular risk factors and aortic stenosis: the CAN HEART Aortic Stenosis Study. Journal of the American College of Cardiology, 69(12), 1523-1532.