Myocardial contusion: effect of intra-aortic balloon counterpulsation on cardiac output.

Intra-aortic balloon counterpulsation (IABCP) improves impaired left ventricular (LV) performance associated with myocardial ischemia. We have evaluated the effect of IABCP on cardiac output (CO) after blunt trauma to the heart where LV performance is impaired by myocardial contusion but coronary blood flow is normal. Contusion of 20 to 40% of the LV in 13 dogs decreased CO by 41% +/- 6.4. A 30-minute period of IABCP was followed by 30 minutes without IABCP with three assist periods in each animal unless death occurred. Immediate IABCP after injury in six dogs increased CO 14% +/- 3.8 (p less than 0.01). Treatment was delayed for 30 minutes in seven dogs, and CO further decreased 0.7% +/- 3.2; initiation of IABCP then increased CO 9.2% +/- 6.5 (p less than 0.05). When CO was decreased less than 25% or greater than 50% after injury, IABCP had no effect on CO. In midrange when CO decreased 25 to 50%, IABCP increased CO 12.5% +/- 3.2 (p less than 0.001 initially, 9.3% +/- 1.3 (p less than 0.005) with second assist, and third assist 5.6% +/- 2(NS). It is concluded that IABCP improves LV performance following myocardial contusion, especially when applied early after injury.