Assessment of left ventricular function during exercise; the use of radionuclide cineangiography
In patients with many forms of heart disease, left ventricular function is normal or nearly normal when the patient is at rest, even when disease clinically is moderately severe. However, the interposition of stress, such as that produced by physical exercise, causes demand for left ventricular work to exceed functional reserve capacity, with functional abnormality then becoming apparent. Until recently, assessment of left ventricular function during exercise has required invasive techniques, and thus has been impractical in many clinical situations. However, with the development of radionuclide cineangiography, a computer-based method for making movies of the beating heart in less than 2 minutes of imaging, it has become possible to assess regional and global left ventricular function, not only at rest but during intense exercise. We have now employed radionuclide cineangiography during exercise in the study of more than 2000 patients with various forms of heart disease. The following data will illustrate the variety of situations in which the technique can be usefully employed clinically.
In evaluating the efficacy of the method in detecting coronary artery disease, we found that in 35 normal subjects, no regional dysfunction was present at rest or during exercise; left ventricular ejection fraction invariably rose during exercise (mean ejection fraction 57% at rest, 71% with exercise, p < 0.001), However, in 59 of 63 (93%) patients with coronary artery disease, whether or not regional dysfunction was present at rest, at least one region of dysfunction was noted during exercise, invariably corresponding to the area of distribution . . .