[The cardiac hazard of tocolysis and antagonising possibilities. I. The haemodynamic situation of the patient during tocolysis/Protection of the myocardium by means of cardioselective beta-blockade. Experimental results (author's transl)].

7 mongrel dogs underwent general anaesthesia and thoracotomy. For the assessment of the haemodynamic situation the following parameters were measured: Left ventricular and aortic pressure, coronary flow, oxygen-saturation in the coronary sinus, pulmonal arterial pressure, central venous pressure, heart rate. From these measurements cardiac output volume and myocardial oxygen consumption could be calculated. Using an ultrasound transit-time method regional myocardial function could be assessed. After the establishment of these measurements Fenoterol has been given in an increasing dosage up to the upper therapeutical range. Then additionally the cardioselective beta-antagonist Metoprolol was administered stepwise up to a total dose of 1.2 mg/kg body weight. The measurements proved evidence, that a relatively small dose of 0,2-0,4 mg Metoprolol/kg body weight is sufficient to compensate the haemodynamic situation impaired by Fenoterol, esp. the rise in myocardial oxygen consumption.