Kenichi Harumi

Publications (2)2.15 Total impact

• Article: Exercise‐induced QTc‐interval changes for predicting improvement in regional blood flow in ischemic myocardium and cardiac output after coronary angioplasty in patients with right bundle‐branch block

  Takuya Watanabe M.D, Takashi Katagiri M.D, Hideyuki Yamanaka M.D, Yasushi Akutsu M.D, Tetsuo Michihata M.D, Osamu Okazaki M.D, Facc Kenichi Harumi M.D, Takuya Watanabe, Takashi Katagiri, Hideyuki Yamanaka, Yasushi Akutsu, Tetsuo Michihata, Osamu Okazaki, Kenichi Harumi
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  ABSTRACT: Background: We have previously shown that QT-interval changes are more useful than ST-T changes in evaluating the severity of exercise-induced myocardial ischemia in patients with right bundle-branch block (RBBB).Hypothesis: The purpose of this study was to evaluate whether the improvement in regional myocardial blood flow (RMBF) in ischemic areas and cardiac output after percutaneous transluminal coronary angioplasty (PTCA) can be predicted by exercise-induced QT-interval changes prior to PTCA.Methods: The RMBF and cardiac output were quantified with nitrogen-13 ammonia positron emission tomography at rest and during exercise in 20 patients with RBBB and ischemic heart disease before and 6 months after PTCA, and in 9 healthy volunteers.Results: Before PTCA, exercise-induced prolongation by <20 ms or shortening of the Bazett-corrected QT (QTc) interval (454 ± 38 to 451 ± 41 ms, p = NS) was observed in 13 patients (Group 1) and prolongation by ≥20 ms (429 ± 44 to 466 ± 50 ms, p < 0.002) was observed in 7 (Group 2). The number of regions of exercise-induced ischemia was significantly greater in Group 2 than in Group 1 (4.0 ± 1.2 vs. 2.1 ± 1.2, p < 0.01). The RMBF in regions of exercise-induced ischemia and cardiac output at rest was not significantly different between Groups 1 and 2, whereas during exercise both the parameters were significantly lower in Group 2 than in Group 1 (both p < 0.05). After successful PTCA, RMBF both at rest and during exercise improved significantly in Group 1 (0.67 ± 0.04 to 0.71 ± 0.06 ml/min/g, 0.74 ± 0.05 to 0.84 ± 0.08 ml/min/g; both p < 0.0001), but did not improve significantly in Group 2 (0.63 ± 0.05 to 0.65 ± 0.07 ml/min/g, 0.65 ± 0.04 to 0.69 ± 0.11 ml/min/g; both p = NS). Cardiac output during exercise improved significantly in Group 1 (6.4 ± 0.7 to 7.4 ± 0.9 l/min; p<0.002) but not in Group 2 (5.7 ± 0.6 to 5.9 ± 0.6 l/min; p = NS).Conclusions: Our results suggest that the marked prolongation of the QTc interval induced by pre-PTCA exercise may predict a lack of improvement in RMBF in ischemic areas and cardiac output after PTCA in patients with RBBB and ischemic heart disease.
  Clinical Cardiology 04/2000; 23(5):359 - 364. · 2.15 Impact Factor
• Article: Exercise-induced ST-segment changes permit prediction of improvement in left ventricular ischemic dysfunction after revascularization: Evaluation with positron emission tomographic measurements of regional myocardial blood flow and cardiac output

  Takuya Watanabe, Kenichi Harumi, Tetsuo Michihatas, Osamu Okazaki, Hideyuki Yamanaka, Yasushi Akutsu, Takashi Katagiri
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  ABSTRACT: Background. Prediction of the recovery of left ventricular (IV) ischemic dysfunction after revascularization is important in patients with coronary artery disease (CAD). We investigated whether the improvement in LV ischemic dysfunction after revascularization could be predicted preoperatively by exercise-induced ST-segment changes.Methods and Results. Regional myocardial blood flow (RMBF) and cardiac output were measured with nitrogen 13—ammonia positron emission tomography at rest and during low-level exercise in 28 patients with angiographically proven CAD before and after successful revascularization and in 9 normal subjects. Before revascularization, exercise-induced upsloping ST-segment depression <1 mm 80 msec after the J-point was observed in 11 patients (group 1), horizontal depression of 1 to 1.5 mm was observed in 9 patients (group 2), and downsloping depression ≥1.5 mm was observed in 8 patients (group 3). The number of regions of critical CAD was greater in group 3 than in groups 1 and 2 (3.6 ± 1.4 vs 1.6 ± 0.7 and 2.2 ± 1.1, p < 0.001, p < 0.02). Increase of RMBF in regions of critical CAD with exercise was lower in group 3 than in groups 1 and 2 (0.15 ± 0.01 vs 0.22 ± 0.01 and 0.18 ± 0.02 ml/min per gram, p < 0.0001, p < 0.01). After revascularization, RMBF in regions of critical CAD both at rest and during exercise improved in groups 1 (0.49 ± 0.15 to 0.60 ± 0.18, 0.70 ± 0.26 to 0.86 ± 0.33 ml/min per gram, both p < 0.05) and 2 (0.50 ± 0.15 to 0.62 ± 0.19, 0.67 ± 0.26 to 0.89 ± 0.31 ml/min per gram, both p < 0.02), but was unchanged in group 3 (0.47 ± 0.09 to 0.47 ± 0.15, 0.62 ± 0.17 to 0.64 ± 0.23 ml/min per gram, both p = NS). Cardiac output at rest improved in groups 1 (4.98 ± 0.43 to 5.35 ± 0.50 L/min, p < 0.02) and 2 (5.08 ± 0.52 to 5.53 ± 0.28 L/min, p < 0.02), but was unchanged in group 3 (4.76 ± 0.48 to 4.88 ± 0.82 L/min, p = NS).Conclusions. Our results suggest that marked downsloping ST segment depression induced by preoperative low-level exercise may predict a lack of improvement in IV ischemic dysfunction after revascularization.
  Journal of Nuclear Cardiology.