Long-term intermittent urokinase therapy in an applied dose of 3 X 500,000 IU/week represents an effective anti-ischemic and antianginal approach for patients with refractory angina pectoris and end-stage coronary artery disease. Apart from rheologic improvement, antithrombotic properties and plaque regression are likely anti-ischemic mechanisms.

Asynergic myocardial regions in patients with coronary artery disease can be viable. They may have the ability to improve their function after restoring coronary blood flow. Asynergic but viable myocardial regions have a positive inotropic reserve which can be stimulated by catecholamines. Because echocardiography is an established method for evaluating regional left ventricular function, it has the potential to detect the inotropic response of asynergic myocardial regions. In the clinical setting, prediction of left ventricular functional improvement after revascularization is particularly important. Dobutamine stress echocardiography is the most frequently used stress echocardiographic test for detection of myocardial viability. Dobutamine is infused at low rates of 2-5 to 20 ug. kg ~ '. min ~ ' to detect myocardial viability. This paper reports on the sensitivity and specificity of the method for the detection of viability and its usefulness for prediction of left ventricular functional improvement after revascularization.

99mTc-mercaptoacetyltriglycine (MAG3) has recently been introduced for imaging kidney function. Due to the much lower radiation dose per MBq, the total administered activity can be much higher than in the case of 131l-ortho-iodo-hippurate (OIH). The improved counting statistics make this tracer useful for parametric imaging of the kidneys. To investigate this potential of MAG3, its kinetics was compared with that of the reference tracer OIH in 38 patients. Parameters of extrarenal tracer kinetics such as the distribution volumes, the whole-body elimination times and the clearance rates showed a good correlation; however, the clearance rate of MAG3 was always lower than that of OIH. The intrarenal kinetics was investigated using the transfer function which was calculated by deconvolution analysis of the renographic curves. Parameters of the transfer function such as the amplitude, extraction fraction and mean transport time demonstrated a high correlation between the two tracers. Since MAG3 seems to be suitable for parametric imaging of kidney function, parametric images of perfusion, uptake, extraction and transport times were calculated by deconvolution analysis of the MAG3 pixel-renograms in various renal disorders. The parameters were distributed homogenously throughout the parenchyma of normal kidneys. In a kidney with a hemodynamically significant renal artery stenosis the perfusion parameter was decreased and the time parameter was prolonged. Further examples of a renal graft acute tubular necrosis, an obstructive uropathy, an obstructive nephropathy and of a horse-shoe kidney demonstrate that the parametric images are useful for quantitative investigation of regional renal function.

No abstract