Diastolic dysfunction in post-cardiac surgical management.
Although an appropriate definition of primary diastolic failure is still not at hand, primary diastolic failure is a distinct pathophysiologic syndrome. It is due to an increased resistance to ventricular filling and results in an inappropriate upward shift of the diastolic P-V relationship, especially during exercise. This leads to exercise intolerance with symptoms of congestion. The causes are known, ie, impaired systolic relaxation, decreased diastolic compliance, and inappropriate tachycardia. Pathophysiologically impaired (incomplete or slowed) systolic relaxation must be distinguished from physiologic, compensatory prolonged contraction (delayed or retarded relaxation). Treatment of diastolic failure is feasible, but necessitates a clear understanding of the etiology, pathogenesis, and pathophysiology of the underlying cardiac disease. Optimal therapy will depend on the type of disease, on the phase during the pathophysiologic evolution of a given disease, and on the coexistence and relative contribution of various compensatory or decompensatory mechanisms. This often requires a comprehensive analysis of hemodynamics, for example, with echo-doppler, completed, whenever necessary, by catheterization.