[Results of the use of the counter-pulsation balloon in experimental post coronary oclussion cardiogenic shock in closed thorax].

An experimental study of the production of cardiogenic shock together with the results of its treatment by means of the intraaortic balloon was carried out. Cardiogenic shock was produced in dogs with closed thorax and spontaneous respiration. In 13 of the 21 dogs studied, the production of acute myocardial infarction by means of selective embolism of the left circumflex artery permitted the reproduction of a model of cardiogenic shock. Embolism was produced by injecting metalic mercury through a double catheter. Six of the 8 remaining dogs died due to accidental introduction of mercury in the anterior descending coronary artery which produced irreversible ventricular fibrillation. The other 2 died due to rupture of the ascending aorta during the maneuveres to place the coronarygraphy catheter. The 13 dogs with cardiogenic shock were treated with intraaortic balloon pumping during 3-4 hours. The left ventricular systolic pressure fell from 128 +/- 12.07 to 124 +/- 4.65 mm. Hg. The cardiac index increased by 42%. These findings confirm the fact that intraaortic balloon pumping lessens the after load. The fall of the telediastolic pressure by 20% was an index of the lessening or the preload. The aortic telediastolic pressure rose by a mean value of 32.21 mm. Hg. This raises the coronary perfusion pressure thus limiting the extension or reducing the size of the infarction. A frank reduction of the electrographic subepicardiac lesion was observed after using intraaortic balloon pumping. The mean aortic pressure only rose by 8%, the central venous pressure remained unchanged and the increase in diuresis was not estimable. The maximum dP/dt was unaltered and the Vmax. rose 17%. Two dogs were left alive after the experiment and lived for 3 and 12 days respectively. To conclude the results obtained permit us to indicate that intraaortic balloon pumping when used in dogs with this standard type of cardiogenic shock produces an important reduction of the after load, a discrete reduction of the preload and a significative increase in coronary blood flow. There were no changes in cardiac frequency and although the results of myocardial contractility were not definite, they seem to indicate a moderate improvement.