The mechanism of ischemic adaptation is still controversial partially because of the difficulty in assessing recruitable collateral circulation in the occluded myocardium in humans. Using myocardial contrast echocardiography (MCE), We sought to assess whether ischemic adaptation is attributable to myocardial preconditioning (MP), collateral recruitment (CR), or both. The clinical, electrocardiographic, hemodynamic, and echocardiographic responses to repeated three 150-sec occlusions of the left anterior descending artery were assessed in re-lation to CR in 15 patients with effort angina undergoing elective PTCA. At the 1st inflation, CR in the occluded myocardium was shown by MCE in 6 patients (Group C) and not in 9 patients (Group N). In Group N, all patients manifested severe ischemic signs during each inflation. However, subjective symptoms (scores of 0, none to 10, severe; 5.4±.3.9 versus 3.8±3.1; p=0.03) and ST segment shift (0.39±0.24 versus 0.24±0.22mV; p= 0.02) significantly decreased from the 1st to the 3rd inflation, suggesting the occurrence of MP. The extents of elevation in mean pulmonary arterial pressure and deterioration of anterior wall motion were comparable between the 1st and the 3rd inflation in Group N. In contrast, in Group C, myocardial ischemia was significantly eliminated during balloon infaltion (p< 0.01 versus Group N), and no preconditioning effect was observed. In each group, the extent of CR did not differ between the 1st and the 3rd inflation. Thus MCE in conjunction with PTCA enabled us the simultaneous assessment of deterioration of wall motion and CR in the clinical settings, and showed that ischemic adaptation was attributable to both MP and CR in humans.
|Number of pages||1|
|Journal||Journal of the American Society of Echocardiography|
|Publication status||Published - 1997 Dec 1|
ASJC Scopus subject areas
- Radiology Nuclear Medicine and imaging
- Cardiology and Cardiovascular Medicine