Peripheral vasoconstriction and sympathetic stimulation result in increased vital organ perfusion at the expense of increasing cardiac work. The retained salt and water increase preload, but in the long term pulmonary and peripheral edema occur. Increased beta receptor stimulation leads to increased heart rates and cardiac work in order to increase and maintain cardiac output. Over time, the increased stimulation leads to decreased receptor density and function. The myocardial cells then become less responsive to sympathetic stimulation and cardiac output drops.
Cardiac hypertrophy helps improve systolic function and unload cardiac muscle fibers.
This eventually leads to dilated cardiomyopathy and cardiac cell death. Presenting Signs and Symptoms Direct manifestations of decreased cardiac output are the presenting symptoms in some patients. Fatigue, weakness, malaise, lightheadedness, and lethargy are common. Vascular congestion results in pulmonary venous hypertension, with symptoms of cough, dyspnea on exertion, shortness of breath, orthopnea, and paroxysmal nocturnal dyspnea. Pulmonary edema is the most severe manifestation of pulmonary venous congestion.