Defined: “An abnormal clinical condition involving impaired cardiac pumping that results in pathophysiologic changes in vasoconstriction and fluid retention” (Lewis, Heitkemper, Dirksen, O’Brien, Bucher, 2007, p. 821). Risk factors: Increasing age and coronary artery disease are the two main risk factors for heart failure. Heart failure may also develop by other contributing risk factors, such as cigarette smoking, diabetes, high cholesterol, obesity, and hypertension (Lewis, et al, 2007, p. 821).
Other risk factors may include the physical structure of the heart. For example, a patient may have endured damage to the heart due to a myocardial infarction, or a heart attack. Pathophysiology: The heart is a vital organ in the human body. It functions to pump deoxygenated blood to the lungs and oxygenated blood to the rest of the body. Oxygenated blood is crucial to the functioning of the organs and perfusion of tissues, which in turn is crucial to the functioning of the body as a whole. In Lewis, et al, it traces the blood flow of the heart:
The right atrium receives venous blood from the inferior and superior venae cavae and the coronary sinus. The blood then passes through the tricuspid valve into the right ventricle. With each contraction, the right ventricle pumps blood through the pulmonic valve into the pulmonary artery and to the lungs. Blood flows from the lungs to the left atium by way of the pulmonary veins. It then passes through the mitral valve and into the left ventricle. As the heart contracts, blood is ejected through the aortic valve into the aorta and thus enters the high-pressure systemic circulation. (p. 740).
As the blood flow is ejected into the systemic circulation (afterload), it is ejected into the arterial side of circulation from the left ventricle. The blood then returns, via the venous side of circulation, to the right atrium (preload). This blood flows through the vascular system, perfusing tissues and organs, which is needed for proper functioning. There are two types of heart failure, left-sided failure and right-sided failure. Left-sided failure is the most common type of heart failure, although it eventually leads to right-sided failure, known as biventricular failure when both sides of the heart fail.
Left-sided failure deals with the left ventricle and its inability to eject the blood into the arterial circulation. So, by tracing back the blood flow, if the left ventricle is unable to eject the blood, the blood will back up into the lungs and cause respiratory symptoms: crackles in the lungs upon auscultation, bronchial wheezing, dyspnea, hypoxia, respiratory acidosis, cyanosis, palpitations, and dysrhythmias. Right-sided failure is when the blood backs up into the venous side of circulation from the right atrium.
Symptoms of right-sided failure include: weakness, fatigue, oliguria, hepatojugular reflux, nausea, vomiting, weight gain, abdominal distention, ascites, and jugular vein distention (Lewis, et al, 2007). When right-sided or left-sided heart failure occurs, the heart tries to compensate. These mechanisms are, but not limited to, ventricular dilation, ventricular hypertrophy, and tachycardia. Ventricular dilation is when the muscles of the heart increase in size as does the blood volume it holds.
This maintains the arterial perfusion needed as well as the blood pressure. If uncorrected, ventricular hypertrophy occurs. “Hypertrophy is an increase in the muscle mass and cardiac wall thickness in response to overwork and strain” (Lewis, et al, 2007, p. 823). Tachycardia then occurs, which increase cardiac output, workload, and oxygen demand, but decrease coronary circulation of the heart. Then, when all else fails, the heart tires from working hard and trying to compensate, and the heart goes into failure.
Complications: Since the blood flow is a continuous cycle, running through the systemic circulation, it can lead to complications such as pleural effusion. “Pleural effusion results from increasing pressure in the pleural capillaries” (Lewis, et al, p. 826). Due to the enlargement of the heart, the electrical impulse that creates the heart beat is also altered, causing a misfiring of electrical conductivity which in turn causes dysrhythmias, or abnormal heart rhythms. Left ventricular thrombus may also occur with failure.
“The enlarged LV [left ventricle] and decreased CO combine to increase the chance of thrombus formation in the LV” (Lewis, et al, p. 826). These patients are often on anticoagulants to reduce thrombus formation. Hepatomegaly occurs from the back up of blood in the venous system. The liver is overloaded with the fluid back up and the liver function slowly diminishes. Renal failure is caused by the decreased perfusion of the kidneys. Sufficient blood flow is needed for the kidney to filter and excrete wastes and urine. Without the proper perfusion of the kidneys, the patient may go into renal failure (Lewis, et al, 2007.