Value and limitations of the precordial Xenon-clearance technique are analyzed. The results of this technique are compared to the scintigraphic display of the initial Xenon distribution and to microsphere scintigraphy (Engel et al. 1976a). 2. The effects of coronary obstructions and of segmental LV dysfunction on regional myocardial blood flow are analyzed (Engel et al. 1977). Independent of coronary obstructions, a clear reduction of regional myocardial blood flow in areas of hypokinesis and akinesis was observed. Thus in coronary disease a decrease of regional myocardial blood flow may represent either a cause or a result of abnormal segmental wall motion. 3. The effects of nitroglycerin, beta-blockade (Atenolol), calcium-antagonists (Nifedipine) and coronary dilatation (Dipyridamole) on regional myocardial blood flow were investigated (Engel et al. 1976b). Regional flow at rest decreased after nitroglycerin and beta-blockade, increased mildly after Nifedipine and markedly after Dipyridamole.
