Functional characteristics of nonischemic region during pacing-induced myocardial ischemia in angina pectoris.

To investigate the details of the hyperfunction of nonischemic area during acute ischemia, the regional myocardial function at rest and immediately after rapid cardiac pacing was compared using cineventriculography in 12 patients with stable effort angina. Three left ventricular boundaries at the time of end-diastole, aortic valve opening and end-systole were superimposed, and 128 radial grids were drawn from the center of gravity of end-diastolic frame to the endocardial margin. The changes in the length of each radial grid provided quantitative description of segmental systolic function. In the ischemic area, the percent of total segment shortening decreased from 36 +/- 6% (mean +/- standard error of the mean) to 24 +/- 8% (p less than 0.05) in patients with a significant narrowing of left anterior descending coronary artery (LAD), and from 42 +/- 6% to 20 +/- 4% (p less than 0.05) in those with right coronary artery (RCA) involvement. In the nonischemic area, the percent of total segment shortening increased from 33 +/- 7% to 44 +/- 7% (p less than 0.05) in LAD disease, while it was unchanged in RCA involvement (40 +/- 5% vs 41 +/- 7%). The percentage of isovolumic segment shortening increased from 1 +/- 4% to 7 +/- 3% (p less than 0.05) and from 1 +/- 1% to 5 +/- 2% (p less than 0.05) in LAD and RCA involvement, respectively. Meanwhile, ejection phase shortening did not change significantly (33 +/- 6% vs 40 +/- 7% in LAD involvement, and 39 +/- 6% vs 38 +/- 7% in RCA involvement).(ABSTRACT TRUNCATED AT 250 WORDS)