Radioisotopic studies during exercise testing: how valuable?

Abstract

Myocardial imaging and exercise radionuclide angiography have proven useful in the detection of exercise-induced regional dysfunction. EF monitoring is, however, inadequate to detect deterioration of cardiac performances with complex changes in the ventricular loading conditions. Measurement of absolute volumes and especially of end-systolic volume by a count-derived technique will further enhance the value of this method when attenuation correction can be consistently performed. Non-invasive estimates of end-systolic indices could then be obtained. Concomitant evaluation of right ventricular ejection and function provides data on ventricular interdependence and allows quantification of regurgitant lesions and of their changes with exercise. Combined evaluation of these parameters will allow a better definition of the changes occurring in valvular heart disease. Radioisotopic studies also permit evaluation of stress-induced changes in pulmonary blood volume and in the pulmonary distribution of thallium. These parameters, although incompletely studied, could provide further evidence of transient LV dysfunction and deserve further study.