Diastolic hea failure is impairment in the filling of the left ventricle. Which of the following is LEAST likely to occur?
Improvement of the patient's condition with administration of calcium channel blocker
Decreased compliance of the hea Increased left atrial pressure
Increased left atrial pressure
Improvement of patient's condition with administration of a positive inotropic agent
Diastolic dysfunction is an impairment in the filling of the left ventricle ("stiff ventricle") caused by decreased compliance at a normal left atrial pressure. Systolic hea failure, which is an impairment in contractility, has a better response to positive inotropic agents. Most patients have a combination of both systolic and diastolic dysfunction.In diastolic hea failure, filling of the left ventricle is slow or incomplete (i.e., decreased compliance) unless left atrial pressures increase to maintain the ejection fraction at the expense of increasing pulmonary and systemic venous congestion. Clinical findings include dyspnea, which is the most common symptom, resulting from interstitial and pulmonary edema. Pathophysiologically, there is left atrial hypeension and pulmonary venous hypeension, leading to pulmonary congestion. Therapy is aimed at slowing the hea rate, which promotes filling of the left ventricle at low pressures. -Adrenergic blockers and calcium channel blockers are effective. Patients with diastolic dysfunction have a better survival rate than those with systolic dysfunction, because the ejection fraction is normal to slightly decreased, albeit at the expense of increased left atrial pressures.Systolic dysfunction is an impairment in contractility of the left ventricle or a defect in the ability ofmyofibrils to shoen against a load. The left ventricle loses its ability to eject blood into the aoa, so the ejection fraction (i.e., stroke volume/left ventricular end-diastolic volume) is decreased (usually < 40%); the normal ejection fraction is 80/120, or 66%, with a range of 55% to 75%. The ejection fraction is measured by echocardiography or radionuclide ventriculography. Signs of isolated systolic dysfunction include fatigue, prerenal azotemia, cool skin, and mental obtundation. The left ventricular chamber eventually dilates and patients develop fatigue, dyspnea, and peripheral edema, which are signs of right-sided hea failure. Examples of systolic dysfunction include post-myocardial infarction, ischemic injury (e.g., acute myocardial infarction), and congestive cardiomyopathy. Therapy is aimed at improving the performance of the left ventricle with the administration of positive inotropic agents and peripheral vasodilators to decrease peripheral resistance.
Cardiovascular system