CHF - Congestive Heart Failure PDF

CHF · Definition: ○ Congestive heart failure (CHF) is not a specific disease but a common, progressive pathophysiologic syndrome that describes several types of cardiac dysfunction that cause poor perfusion of tissues with vital blood-borne nutrie...

CHF · Definition: ○ Congestive heart failure (CHF) is not a specific disease but a common, progressive pathophysiologic syndrome that describes several types of cardiac dysfunction that cause poor perfusion of tissues with vital blood-borne nutrients and oxygen. ○ Sluggish blood flow (congestion) and tissue swelling (edema) are also major components of CHF. CHF is also known in the medical literature as cardiac failure, ventricular failure, or simply heart failure. Significance: ○ Depending on the stage to which heart failure has progressed, mortality is significant and may exceed 50% within 5 years of diagnosis. ○ Shortness of breath (dyspnea), fatigue, exercise intolerance, abdominal pain, nausea with loss of appetite, and significant swelling of the feet and ankles are especially bothersome. ○ The accumulation of fluid within the lungs (pulmonary edema) is a serious and life-threatening complication of this condition. ○ CHF is the fastest growing clinical cardiac disease entity in the United States. ○ An estimated $23 billion is spent on inpatient management and another $40 billion outpatient management in the United States every year Causes and Risk Factors: ○ CHF is a potential complication of many disease states. ○ In the United States, heart attacks (myocardial infarctions) that result from coronary artery atherosclerosis are the most common cause. ○ Cell death in the heart from reduced blood flow results in poor contractility of heart muscle. ○ High blood pressure (systemic hypertension) is also an important national cause of CHF. ○ Cardiomyopathies (a heterogeneous group of progressive, degenerative cardiac disorders), viral infections of the heart (myocarditis), and valvular heart disease are other significant causes of CHF today. ○ Causes of high-output failure in which elevated heart rate is common include: hyperthyroid disease severe anemia. ○ With hyperthyroidism, excessive secretions of the thyroid hormones T3 and T4 result in a hypermetabolic state. ○ With anemia, the oxygen demands of tissues are not met. ○ The strain of increased cardiac performance in the presence of increased metabolic demands or decreased oxygen delivery depletes cardiac reserves and low-output failure eventually ensues. Diagnosis: Clinical Manifestations and Laboratory Tests: ○ CHF may result from decreased right ventricular function (right-sided failure) or left ventricular function (left-sided failure) ○ Since the cardiovascular system is a closed system, both ventricles typically fail with time and bilateral heart failure ensues.  ○ Patients with left heart failure have manifestations of low cardiac output and elevated pulmonary venous pressure. ○ Dyspnea develops more rapidly when the patient is lying down (orthopnea) because decreased venous pressure in the legs increases total blood volume, which elevates preload. ○ Patients often wake up at night feeling that they are suffocating, a condition known as paroxysmal nocturnal dyspnea. ○ This increase in total blood volume in the supine position also explains why nocturia (increased frequency of urination during nighttime hours) is associated with CHF. ○ Signs of fluid accumulation predominate in right heart failure with the ambulatory patient developing pitting edema of the feet and ankles and the bedridden patient developing edema in the buttocks Major signs of compensated heart failure are associated with hyperactivity of the sympathetic nervous system (SNS). ○ These signs include tachycardia and increased contractility (i.e., a “racing and pounding heart” known as palpitations) elevated blood pressure diaphoresis (i.e., excessive sweating) coolness and pallor of the skin. Cardiac hypertrophy with or without structural valvular changes may cause murmurs that can be heard with auscultation. Other signs of compensation result from low cardiac output and a reduction in both renal blood flow and glomerular filtration rate Serious Complications and Prognosis: ○ More than one third of patients hospitalized for CHF are re-admitted within 6 months, and the 5-year survival rate is approximately 50%. ○ Major complications include: pulmonary edema often followed closely by bacterial pneumonia, ventricular arrhythmia cardiac enlargement with developing intracardiac thrombi that embolize, decompensated and refractory CHF. ○ Although the overall prognosis remains poor, probability for survival has improved during the past two decades, in part as a result of more widespread use of ACE inhibitors and beta blockers ○ Effective pharmacologic treatments for CHF include the use of diuretics, inhibitors of the RAA system, beta blockers, digitalis glycosides, vasodilators, and anticoagulants. ○ A combination of a diuretic and an angiotensin-converting enzyme (ACE) inhibitor is the initial treatment in most symptomatic patients. ○ Diuretics are the most effective means of providing symptomatic relief to patients with CHF. ○ When fluid retention is mild, thiazide diuretics (e.g., hydrochlorothiazide) may be sufficient. ○ Thiazide diuretics inhibit sodium reabsorption in the nephron, causing water and sodium loss in the urine (natriuresis). ○ Patients with more severe heart failure should be treated with a loop diuretic (e.g., furosemide), which promotes sodium loss in the urine by inhibiting chloride resorption. ○ Although oral isosorbide and nitroglycerin ointment are effective for long-term therapy, development of tolerance is not uncommon. ○ Nesiritide, a recombinant form of human brain natriuretic peptide, is a potent vasodilator that reduces preload and improves cardiac output. ○ Because sustained hypotension is the primary side effect of the drug, nesiritide is best reserved for patients who remain symptomatic following treatment with diuretics and intravenous nitrates.