Cardiac Function Of Congestive Heart Disease

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This disease is characterised by left ventricular dilation and dysfunction, fibrosis and severe remodeling. Ventricular remodeling is the alteration of the ventricular architecture combined with increased volume as well as the chamber configuration being altered [4]. These changes occur as a result of interstitual fibrosis, myocyte apoptosis, myofibroblast proliferation, and pathogenic myocyte hypertrophy. Cardiac dysfunction causes changes in neurohumoral status [141], vascular function and blood volume [767}. These changes try to help cardiac output by working as compensatory mechanisms (Frank-Starling Mechanism) and arterial blood pressure (systemic vasoconstriction). The Frank-Starling mechanism is “the ability of the heart to change its force of contraction and therefore stroke volume in response to changes in venous return” [911]. The compensatory mechanisms aren’t initially harmful to the heart but over time (months and years) cardiac function will get worse. Thus, the most effective ways to treat congestive heart disease is to use vasodilator and diuretic drugs to modulate arterial and venous pressures [767]. Cardiac Function Congestive heart disease causes a drop in the amount of blood (mL) that is ejected per beat from the left ventricle to the aorta, this is called stroke volume [454]. This is caused by diastolic and/or systolic dysfunction. Diastolic dysfunction are changes in the properties of ventricular diastolic which negatively affect ventricular filling. Around 50% of heart failure patients suffer with diastolic dysfunction. Systolic dysfunction is impaired ventricular contraction, it is likely due to fluctuations in the signal mechanism that regulates cardiac contractions. Resulting in decreased stroke volume... ... middle of paper ... dyssynchronization of the heart. A CRT system has two major components, a pulse generator and three insulated wires, refered to as leads.The leads are placed on the surface of the left ventricle and inside the right atrium and right ventricile. The pulse generator sends small amounts of electrical impulses via the leads to stimulate the ventricule(s). By this action the normal rythm of the heart may be restored and thus both ventricles will pump in synchronization and more efficiently. [122] CRT has been shown to work in carefully selected patients with heart disease. In these patients a CRT device induces left ventricular remodeling, increasing quality of life and decreasing their instances of cardiac related hospital visits. Even though CRT greatly improves symptoms and survival rates, for one-third (30%) of recipents will not receive any clinical benefit. [232]

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