Pathophysiology of congestive heart failure secondary to congestive and ischemic cardiomyopathy.
Dilated cardiomyopathy, owing to any cause, usually culminates in the clinical syndrome of congestive heart failure. Heart failure is characterized by exertional dyspnea and fatigue, but the precise mechanisms that produce these symptoms are still not clear. Sodium retention occurs early in heart failure, but this disturbance is dynamic in nature and is not always present in the patient. The mechanism of early salt and water retention in heart failure is not defined. Gross edema and ascites occur much later, undoubtedly owing to the convergence of a number of factors. The peripheral adaptations to heart failure include activation of the renin-angiotensin system and the sympathetic nervous system, and the release of AVP. The result is an increase in preload with a resultant increase in stroke volume for some patients, but the price is paid in the form of heightened impedance to ejection and circulatory congestion. The sympathetic nervous system disturbances in heart failure are striking, as disturbances in both circulating and myocardial NE levels are consistently found. Vasorelaxant and natriuretic hormones, as well as certain prostaglandins, may be released in an attempt to offset excessive "compensatory" pressor-sodium retentive mechanisms, but the net result seems to be excessive peripheral vasoconstriction and a downward spiral of deterioration in many patients. One would hope that an unraveling of the complex pathophysiology of heart failure would lead to therapy that would change the natural history of the disease. The results of the first V-HeFT trial give room for cautious optimism in this regard.
D002311:Cardiomyopathy, Dilated / Q000150:complications*; D003327:Coronary Disease / Q000150:complications*; D006333:Heart Failure / Q000209:etiology / Q000503:physiopathology*; D006801:Humans