Demonstration of lack of persistence of effectiveness of intra-aortic balloon pumping of short duration in acute myocardial ischemia.

: Experimental studies were carried out to quantitate the effectiveness of intra-aortic balloon pumping (ABP) in reducing severity and extent of myocardial ischemia and the persistence of induced changes after cessation of pumping. Ligation of the anterior descending coronary artery was followed by one hr of observation, IABP for one hr (12 dogs) or 3 hrs (12 dogs) and an additional one hr of observation. Epicardial mapping utilizing 20 electrodes was used to obtain the ST segment elevations (Sigma ST) and numbers of electrodes showing ischemic ST CHANGES (NST) in each group. Reductions of SigmaST of approximately 15% and 33% and reduction of NST of 15% and 20% was observed in the one and 3 hr groups respectively, and persisted throughout the period of pumping. Both parameters were noted to increase within 5 mins after cessation of IABP in both groups. SigmaST frequently rose to almost pre-IABP values in the group pumped for one hr. The group pumped for 3 hrs showed SigmaST increase of approximately 15% and NST increase of approximately 16%. Hemodynamic measurements showed in both groups a mean systolic unloading of approximately 10% and 10-20% mean diastolic augmentation. In conclusion, IABP of short duration (1-3 hrs) early after the onset of acute ischemis (one hr) induces a significant but transient decrease in SigmaST and NST, which reflects a reduction in myocardial ischemia. Further study is required to evaluate the effectiveness of intra-aortic balloon pumping, if intitated several hours after the onset of ischemia, to reproduce the clinical reality of a patient with an acute myocardial infarction.