Evaluation of Repeated Balloon Inflation in Angioplasty as a Clinical Model of Ischemic Preconditioning.

Reevaluation of repeated balloon angioplasty as a model of ischemic preconditioning and of the role of collateral circulation and high-frequency electrocardiograms in repeated inflations was carried out. There have been few studies using angioplasty as a model of ischemic preconditioning of the collateral circulation during repeated inflations or of the use of high-frequency electrocardiograms during angioplasty. Twenty patients underwent 3 repeated balloon inflations, each with a duration of more than 138 seconds. During inflation, ipsilateral and contralateral coronary angiography and signal-averaged electrocardiography were performed. At the 1st inflation, the ST segment gradually increased as the inflation time elapsed. During the 2nd and 3rd inflations, in which ST elevation was nearly equal, the ST segment gradually increased, but it was not as prominent as that at the 1st inflation; thus, the concept that ischemia is gradually ameliorated (adaptation to ischemia) was not documented. Comparison of the maximal ST elevation and ipsilateral and contralateral circulation at each inflation revealed that the ST segment became elevated and the contralateral collateral circulation increased significantly at the 1st inflation compared with those in the control. ST elevation, however decreased significantly and collateral circulation remained unchanged at the 2nd inflation; thus, collateral circulation did not cause the ST elevation decrease. The total root mean square voltage detected by signal averaging decreased significantly only at the 1st inflation. Balloon angioplasty is not always suitable as a model of ischemic preconditioning and collateral circulation is not the cause of ischemic preconditioning.