Transcript
Chapter 13: Alterations in Cardiac Output
Chapter Summary
Valvular disease can be a single disease process or a complex, late-stage disease process. The heart, through compensatory mechanisms, adapts to some degree, but the patient will eventually become symptomatic. Medical management maintains the patient’s lifestyle and cardiac function, but surgical intervention may be required. Anticoagulation is a major component of care for most patients. Astute assessment and comprehensive patient education are the main components of nursing care.
Heart failure (HF) is a clinical syndrome that results from any structural or functional cardiac disorder that decreases the ability of the ventricles to fill or eject. There are four classifications of HF (classes I–IV) and two categories (systolic and diastolic dysfunction). Mechanisms that cause HF are not clearly understood. Several conditions are known to trigger HF, causing cardiomyocyte destruction and activation of neurohormonal mechanisms to compensate for decreased stroke volume. HF has multisystem effects which can produce a variety of symptoms.
Evidence-based practice guidelines for heart failure management include control of risk factors, pharmacologic therapy with ACE inhibitors, beta blockers, and diuretics. Nursing management includes interventions to balance oxygen supply and demand and assessments of vital signs, cardiac rhythms, patient responses to medications, fluid and electrolyte balance, and patient/family education.
Normal blood pressure is defined as SBP less than 120 mm Hg and DBP less than 80 mm Hg; a BP that is consistently higher than this is defined as hypertension. There are three stages of hypertension: prehypertension, stage 1, and stage 2. The exact cause of hypertension is not always known; however, there are recognized risk factors that promote its development.
The pathogenesis of hypertension is probably related to activation of the sympathetic nervous system and neurohormonal interactions. Goals of therapy include lowering systolic and or diastolic blood pressures. Management focuses on pharmacologic agents and lifestyle changes. Drugs include ACE inhibitors, ARBs, BBs, CCBs, and diuretics. Nursing management includes accurate assessments of blood pressure, patient education, and monitoring fluid and electrolyte balance.
Hypertensive crisis is a rare complication of poorly controlled hypertension. It is characterized by an abrupt exacerbation of the patient’s blood pressure to at least 180/110–120. If the patient presents with target organ damage, it is called hypertensive emergency, which requires immediate relief of hypertension using intravenous antihypertensive agents. If the patient presents with no evidence of organ damage, it is called hypertensive urgency, and is treated using oral antihypertensives with blood pressure reduction that occurs over several days.
Aortic aneurysm is most commonly a complication of long-term atherosclerosis and is usually seen in older males with a history of hypertension. Aneurysm involves weakening of the tunica media of the aorta that eventually, in the face of hypertension, begins to dilate. If aneurysm becomes too large, it can rupture, causing rapid cardiovascular collapse and death. Aneurysm can also dissect, which involves formation of a false lumen between the tunica intima and tunica media of the aorta at a site of a tunica intima tear or from hemorrhaging vasa vasorum.
