Hemodynamic evaluation of descending aortomyoplasty versus intra-aortic balloon pump performed in normal animals: An acute study

Objective: Aortomyoplasty is a surgical procedure that aims to induce hemodynamic benefits similar to those of the intra-aortic-balloon-pump (IABP). The objective of this study was to compare the coronary blood flow augmentation and afterload reduction produced by IABP and descending aortomyoplasty counterpulsation. Methods: From a series of fifteen mongrel dogs (18-35 kg), eight underwent acute descending aortomyoplasty and seven had IABP application. Left anterior descending (LAD) coronary artery blood flow was measured using a Doppler flow probe. Left ventricular pressure in addition to aortic pressures both proximal and distal to either the aortomyoplasty site or the IABP position were monitored continuously. All experiments were acute and performed in normal hearts. Results: Descending aortomyoplasty induced a 27% increase in the LAD blood flow integral during assisted beats (14.0±6 ml/min integral compared to 10.8±4 ml/min integral in unassisted beats [P<0.001]). This was comparable to an 18% rise in the LAD blood flow integral during IABP counterpulsation (from 8.6±3 ml/min to 10.2±4 ml/min [P<0.001]). Conversely, while IABP counterpulsation reduced the left ventricular afterload by 16% (from 102±23 mmHg to 86±26 mmHg [P<0.001]), descending aortomyoplasty did not result in afterload reduction. Conclusions: Descending aortomyoplasty produces coronary blood flow augmentation comparable to that achieved by the IABP. This may be important for end-stage ischemic patients. However, afterload reduction achieved by the IABP was not reproduced during descending aortomyoplasty counterpulsation. The surgical technique of descending aortomyoplasty should be modified to attain afterload reduction, thus improving treatment for congestive heart failure patients.