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C155PATHOPHARMACOLOGICAL FOUNDATIONS FOR ADVANCED NURSING PRACTICEC155Western Governors UniversityMay 23, 2018
C155 PATHOPHARMACOLOGICAL FOUNDATIONS2Heart FailureHeart failure, as defined by the American Heart Association (AHA), is a condition inwhich the heart is no longer able to pump blood efficiently (What is Heart Failure, n.d.). Itaffects an estimated 26 million people across the globe (Aguanno & Samson, 2017). There canbe several reasons for someone developing heart failure, from improperly working heart valves,to a myocardial infarction (MI), or “heart attack”, that can leave the heart muscle weakened.There are four different classifications of heart failure, from class 1, which may or may not causeany symptoms, and only minimally inhibits normal daily activities, to class 4, which causessignificant outward symptoms and severely limits a person’s ability to be active (What is HeartFailure, n.d.).Pathophysiology of the Disease ProcessThe progression of this disease begins when the heart is unable to keep up with thedemand put on it by an increased need for oxygen and blood to the rest of the body. To make upfor this deficient heart strength, the muscle fibers of the heart stretch to provide a strongercontraction, which will pump more blood with each beat. Just like when any muscle is stretchedagain and again, over time, it gets bigger. Because the heart is a muscle, this exercise enlarges theheart. A larger heart can pump stronger, at least at first. As the heart muscle continues to stretch,it becomes weaker and less efficient. Eventually, the weakened heart can’t stretch its fibers tobecome any larger and a weak, stretched out heart muscle can’t squeeze as well, so less blood ispumped out of the ventricles into the body. Less blood being pumped out of the heart leads to thebody trying to preserve the most important organs, the heart and the brain. It does this bydiverting blood from other non-essential organs. When this diversion occurs, those organs willbegin to function poorly and eventually fail as well. This weak heart continues to get weakerover time, and this reduces the cardiac output even further. Eventually, the heart won’t be able topump enough blood to perfuse even itself and the brain. If this person has not yet died from the
C155 PATHOPHARMACOLOGICAL FOUNDATIONS3multi-system organ failure caused by heart failure, they will probably succumb soon after thispoint.While the heart is compensating for its inefficient pumping by enlarging its muscle fibers,it may also try to compensate by increasing the rate at which it beats. This is an effort by theheart to increase the amount of blood pumped out per minute, rather than by heartbeat. During anormal heartbeat, the valves within the heart open and close in concert with each other to allowthe chambers of the heart to fill and empty appropriately. With a faster heartbeat, these valves nolonger have enough time to allow the heart chambers fill and empty appropriately. This leads tonot enough blood being ejected into the body with each beat. This cascade of events leads to the