[Acute coronary oclussion and cardiogenic shock. Experimental study with closed thorax]

Nineteen dogs in whom an intent to produce cardiogenic shock due to acute myocardial infarction are studied. The dogs are maintained with closed chest and acute myocardial infarction is produced by injecting a bolus of metalic mercury in the left circumflex coronary artery using two different methods. Comparatively, the results show that a more selective embolism is obtained with the double catheter technique than by the introduction of a single coronary arteriograph catheter. Eight of the 19 dogs died. Six due to accidental introduction of mercury in the anterior interventricular artery together with the left circumflex artery, and 2 due to rupture of the ascending aorta during the maneuvre of placing the coronary arteriograph catheter. In the eleven dogs that survived the following parameters were taken every hour during a period of four to six hours. a) Hemodynamic: Left ventricle pressure, cardiac output by thermodilution, maximum dp/dt and Vmax, central venous pressure, cardiac rate and diuresis; b) Metabolic: Gases and lactate in arterial, venous and coronary sinus blood. Cortisol blood levels. All dogs were anaesthetized with thiobarbital during the venous cutdown and later sedated with morfine. They were maintained breathing atmospheric air. Cardiogenic shock was established when the diuresis fell from 170 cc/hour to an average of 43 cc/hour, the mean arterial pressure fell by 20%, the cardiac output by 58%, Vmax descending 20%, the telediastolic pressure of the left ventricle rose from 2.8 mm. Hg to 19.6 mm. Hg and the presence of acidoses was demonstrated by metabolic studies.

Since the dog is maintained with a closed chest and breathing atmospheric air, this is an excellent method for the production of cardiogenic shock in conditions similar to the humain without the influence of other variables. In this way a better knowledge of shock is obtained and different terapeutic measures can be studied.