Congestive heart failure: systolic and diastolic function.
There is increasing recognition that disorders of both left ventricular systolic and diastolic function can result in congestive heart failure. As such, consideration of both the filling and emptying characteristics of the left heart is needed to evaluate the hemodynamic abnormalities present in this syndrome. Considerations of the systolic (emptying) and diastolic (filling) pumping characteristics of the left heart also provides a conceptual basis to classify and understand the pathophysiology of congestive heart failure. In this context, systolic dysfunction can be defined as impaired emptying of the LV, apparent as a decreased (< 50%) effective ejection fraction (forward stroke volume divided by end-diastolic volume). Systolic dysfunction may result from impaired myocardial contractile function, increased left ventricular afterload, and/or structural abnormalities of the left heart. Diastolic dysfunction can be defined as a condition in which filling of the LV sufficient to produce an adequate cardiac output requires an elevated pulmonary venous pressure. Thus, diastolic dysfunction is clinically manifested as pulmonary congestion. Defined in this manner, the most common cause of diastolic dysfunction is systolic dysfunction. In fact, the most common symptom of patients with systolic dysfunction is dyspnea from the resulting diastolic dysfunction. Diastolic dysfunction in the setting of normal systolic function may be due to obstruction of left ventricular filling, impaired left ventricular distensibility, or extensive external compression of the LV. Treatment of diastolic dysfunction can be accomplished by relieving myocardial ischemia, improving systolic function, lowering arterial systolic pressure, and decreasing cardiac distention.
Little
W C
WC
Bowman Gray School of Medicine, Department of Internal Medicine, Winston-Salem, NC 27157-1045.
Applegate
R J
RJ
D002302:Cardiac Output / Q000502:physiology; D003971:Diastole / Q000502:physiology*; D006333:Heart Failure / Q000503:physiopathology*; D006801:Humans; D009200:Myocardial Contraction / Q000502:physiology; D013599:Systole / Q000502:physiology*; D016277:Ventricular Function, Left / Q000502:physiology*