In the early stages, shortness of breath occurs only when the patient is physically active. Later, as the heart action becomes more seriously impaired, the dyspnea is present even when the patient is resting. These attacks usually are accompanied by coughing and wheezing, and the patient seeks relief by sitting upright. Orthopnea and paroxysmal nocturnal dyspnea are related to congestion of the pulmonary blood vessels and edema of the lung tissues. They are aggravated by lying down because in the prone position quantities of blood in the lower extremities move upward into the blood vessels of the lungs.
Fluid retention is another common symptom of congestive heart failure.
In left-sided failure there is higher than normal pressure of blood in the pulmonary vessels. This increased pressure forces fluid out of the intravascular compartment and into the tissue spaces of the lungs, causing pulmonary edema. Right-sided failure causes congestion in the capillaries of the peripheral circulation and results in edema and congestion of the liver, stomach, legs, and feet, and in the sacral region in bedridden patients. Decreased cardiac output also affects the kidneys by reducing their blood supply, which in turn causes a decrease in the rate of glomerular filtration of plasma from the renal blood vessels into the renal tubules. Sodium and water not excreted in the urine are retained in the vascular system, adding to the blood volume.