Pathophysiology

Pathophysiology Study Guide

reduced flow of blood to the heart muscles due to blocking and narrowing of the arteries; adequate supply of oxygen and other nutrients cannot reach the heart, which leads to failure. Another cause is heart attack. In the case of heart attack, the coronary artery gets blocked and the flow of blood to the heart muscles gets hampered. Cardiomyopathy like infections and drug abuse also cause weakening of the heart muscles and heart failure. The two most common reasons for systolic heart failure are coronary heart disease and prior myocardial infections, known as ischemic cardiomyopathy. The next major cause is dilated cardiomyopathy, which can be idiopathic or viral cardiomyopathy, or hypertensive heart disease caused by alcohol, stress, doxorubicin, deficiency of selenium or thiamine, or related to tachycardia mediated, giant cell arteritis, use of cocaine, and hereditary cardiomyopathies. Other causes of cardiac vascular disease include aortic or mitral valve stenosis or regurgitation. Compensatory Responses Congestive heart failure triggers multiple compensatory mechanisms so as to enhance the output of the heart. If this mechanism works for a longer term, it can impact the heart adversely through negative remodeling. The primary mechanism known as neurohormonal includes activating the sympathetic nervous system (SNS) and renin-angiotensin-aldosterone system (RAAS). During heart failure, the SNS senses the reduction in the blood pressure and increases the levels of epinephrine and norepinephrine to raise the heart rate, afterload, and contractility through peripheral vasoconstriction. These activated mechanisms are reduced using medical therapy like beta blockers. RAAS is activated when the kidney assumes hypovolemia and renal perfusion falls. This mechanism helps to retain sodium and water. This mechanism can be stopped with the help of ACA inhibitors, aldosterone antagonists, ADF antagonists, and angiotensin receptor blockers. There is another compensatory response mechanism through A type and B type natriuretic peptide. These have healthy hemodynamic influence at the time of congestive heart failure and are released in the atrium and vasolidate. In this process, sodium is excreted and results in natriuresis. Clinical Manifestations Right-Sided Heart Failure Right-sided heart failure occurs when the right side of the heart is not able to pump blood efficiently. In this case, the right ventricle loses the pumping function, and the blood is backed up in other organs, causing congestion. This happens mostly due to coronary heart disease, left-sided heart failure, lung diseases (chronic bronchitis), clotting in the pulmonary arteries, heart valve disease, and pulmonary hypertension. Symptoms of right-sided heart failure include shortness of breath, feet and ankle swelling, frequent urination at night, pronounced neck veins, a rise in palpitations, an irregular and fast beat of the heart, weakness, fatigue, and fainting.

©2018

Achieve

Page 51

of 131

Made with FlippingBook - professional solution for displaying marketing and sales documents online