Daisuke Masuda

Evaluation of coronary blood flow reserve by13N-NH3 positron emission computed tomography (PET) with dipyridamole in the treatment of hypertension with the ACE inhibitor (Cilazapril)

PurposeThe purpose of this study was to evaluate the effect of treatment with an angiotensin-converting enzyme (ACE) inhibitor (Cilazapril) for early hypertensive patients in terms of coronary blood flow reserve evaluated by13NH3-positron emission tomography (PET).MethodsBefore and after 12 weeks of ACE inhibitor treatment,13NH3-PET with dipyridamole provocation test was performed, and definite myocardial perfusion and coronary flow reserve (CFR) were calculated.ResultsCompared to our normal subjects previously reported (2.61±0.74), average coronary flow reserve was decreased (1.70±0.64 in hypertensive patients), and improved after treatment (1.77±0.52), but not significantly. Of 12 patients, five (42%) showed improved coronary flow reserve from 1.34 to 1.99 without a significant change in the resting flow. Only one patient (8%) showed deterioration after the ACE inhibitor treatment. The coronary vascular resistance (CVR) after ACE inhibitor treatment of the patients with CFR<2.0 decreased significantly compared with those with CFR≧2.0 (p<0.03).ConclusionsThese results indicate that hypertensive patients at the early stage show decreased coronary flow reserve despite having normal resting flow. Treatment with an ACE inhibitor (Cilazapril) for 12 weeks improved coronary flow reserve in 42% of our patients. The CVR of the patients with CFR<2.0 showed improvement compared to those with CFR≧2.0.This result indicates that an ACE inhibitor (e.g., Cilazapril) should be one of the choices for improving CFR if hypertensive patients in early stage show signs of ischemia or diastolic dysfunction, which may be one of the sequels of reserve restriction.

Improvement of oxygen metabolism in ischemic myocardium as a result of enhanced external counterpulsation with heparin pretreatment for patients with stable angina

Enhanced external counterpulsation (EECP) is noninvasive, safe, and effective for stable angina. We have reported that the development of functional collateral vessels is one of the mechanisms of EECP therapy using ammonia positron emission tomography (PET). The efficacy of heparin treatment on collateral growth is shown in several clinical studies. We evaluated whether EECP combined with intravenous heparin injection is effective for exercise capacity and oxygen metabolism of ischemic myocardium in stable angina. Eleven patients with stable angina were treated with conventional EECP therapy (C group). Seven patients with stable angina were treated with EECP therapy with 5000 IU heparin pretreatment (H group). At baseline and after the completion of treatment H, 7 patients underwent [11C] acetate PET to examine the change in regional myocardial oxygen metabolism. Although the total treadmill exercise time was prolonged after treatment in both groups, the extent of the improvements was significantly greater in the H group compared with the C group. Although k mono, the index of regional myocardial oxygen metabolism, in the nonischemic region remained unchanged, k mono in the ischemic region increased significantly (P ≪ 0.05) from 0.038 ± 0.004 to 0.053 ± 0.007. In conclusion, EECP with heparin pretreatment appears to be a new treatment remedy for patients with stable angina.