Value and limitation of digital subtraction angiography for assessment of myocardial perfusion : comparison with systolic wall thickening

We examined the value of degital substraction angiography(DSA) for the assessment of regional myocardial perfusion by comparing with regional myocardial function in 10 anesthetized dogs. With varying degrees of reduction in left circumflex coronary artery (LCX) blood flow (CBF : categories of stenosis (S1-S5), myocardial perfusion was assessed by injecting the contrast medium (1ml by power injector) selectively into LCX, and the regional myocardium with cotrast was imaged with DSA. We recorded aortic pressure (AOP) and systolic wall thickening (%WTh : sonomicrometry) in the ieft ventricular posterior wall simultaneously with cine pulse. On the time-density curve obtained from the myocardial region of interest, we calculated a time interval from the contrast injection to peak concentration (TPC) and exponential washout rate (T). Under varying LCX stenosis, there were to significant change if heart rate and mean AOP and significant linear correlations were found between %WTh and both !/TPC (r＝0.51) and 1/T (r＝0.55). At S1 (CBF : 100-90% of control), neither %WTh nor 1/TPC differed from control, but 1/T was significantly decreased (80% of control p＜0.01). At S3 (CRF : 79-60%) to S5 (CBF : 39-0%), all%WTh, 1/TPC and 1/T were significantly decreased from control (all p＜0.01), however, at S5 (CBF : 39-0%) the value of 1/TPC (71% of control) and 1/T (33%) were not different from that as S4, whereas %WTh was markedly reduced and took place to systolic thinning.. Therefore, in critical coronary stenosis, 1/T was more senstive than 1/TPC or wakk dynamics for assessing myocardial perfusion, however, these indices from DSA had considerable limitation for evaluating the severity of myocardial ischemia when CBF was markedly reduced.