Stress valvular disease

In a broader unselected population referred for nuclear stress testing, Sharir et al. (6) found that the extent of reversible perfusion defect (as expressed by the summed difference score) was the best predictor of subsequent nonfatal myocardial infarction, and was best fit by an exponential curve. Among these patients, 26% had a history of myocardial infarction, and patients with nonischemic cardiomyopathies, valvular disease, or who underwent revascularization within 60 days were excluded. Importantly, even though ejection fraction most powerfully stratified the risk of cardiac death, in patients with an ejection fraction >30% the amount of perfusion defect provided incremental prognostic information. In patients with an ejection fraction of <30%, the rates of cardiac death were high (>4% per year) regardless of the amount of ischemia. 

Pathological cardiac hypertrophy develops in response to stresses, and can be concentric, eccentric, or both. An excess pressure load placed on the heart, for example, resulting from uncorrected hypertension or valvular disease, results in concentric hypertrophy. This hypertrophy is initially believed to be adaptive, normalizing systolic wall stress, though it is not clear that hypertrophy is necessary to maintain systolic function in the face of moderately elevated pressure loads. Eccentric hypertrophy results most often from volume loads such as those in valvular insufficiency. Einally, the hypertrophy that occurs in the remote noninfarcted myocardium, as part of the remodeling process following a myocardial infarction, may be both concentric and eccentric. 

As yet there is no experimental evidence validating current mathematical models which quantitate myocardial stress distributions. However, it will be shown in the following sections that validation in a qualitative sense can be obtained for models which assess myocardial stiffness, employing clinical data obtained from patients with valvular disease. 

Physical or psychological stress, hypoxia, hypokalemia, cardiomyopathy, congenital heart disease. Ml, valvular disease, WoHf-Parkinson-White syndrome, cor pulmonale, hyperthyroidism, and systemic hypertension. 

Echocardiography is useful if the history or physical findings suggest valvular pericardial disease or ventricular dysfunction. In patients unable to exercise, pharmacologic stress echocardiography (e.g., dobutamine, dipyridamole, or adenosine) may identify abnormalities that would occur during stress. 

Myocardial stiffness-stress relationships in valvular heart disease pre and post aortic valve replacement... 

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