Genji Toda

Alteration of antioxidants during the progression of heart disease in streptozotocin-induced diabetic rats.

Involvement of oxidative stress is implicated in the progression of complication of diabetes mellitus. With respect to heart diseases, we have studied role of oxidative stress/antioxidants using rats treated with streptozotocin to induce diabetes (DM). Hemodynamic and echocardiographic measurements showed thickening of the wall and an increase in the internal dimension of the left ventricle (LV) in DM rats at 8th week. Decrease in diastolic posterior wall velocity and rate of LV pressure change, and increase in LV end diastolic pressures also proved cardiac dysfunction. These changes were further developed in DM rats after 12 weeks. Utilizing rat hearts at 8th and 12th weeks, the following estimations were performed. There was a decrease in the activity of Mn-superoxide dismutase (SOD), suggesting abnormal mitochondrial metabolism of reactive oxygen species. The level of glutathione (GSH) decreased concomitant with a decrease in the expression of γ-glutamylcysteine synthetase (γ-GCS). The expression of transforming growth factor-β1 (TGF-β1), known as a growth factor and a suppressor of GSH synthesis, elevated in DM rat hearts. Immunohistochemical estimation showed an increase in type IV collagen in DM hearts. Collectively, it was suggested a linkage between mitochondrial damage to generate reactive oxygen species and inactivation of Mn-SOD and elevation of the expression of TGF-β1 to lead suppression of GSH synthesis and induction of fibrous change for the consequent cardiac dysfunction in DM.

Cardiac Amyloidosis: Typical Imaging Findings and Diffuse Myocardial Damage Demonstrated by Delayed Contrast-Enhanced MRI

Amyloidosis is a rare systemic disease. However, involvement of the heart is a common finding and is the most frequent cause of death in amyloidosis. We report the sonographic, scintigraphic, and MRI features of a pathologically proven case of cardiac amyloidosis. Delayed contrast-enhanced MR images, using an inversion recovery prepped gradient-echo sequence, revealed diffuse enhancement in the wall of both left and right ventricles. This enhancement suggested expansion of the extracellular space of the myocardium caused by diffuse myocardial necrosis secondary to deposition of amyloid.

Administration of nifedipine CR immediately after awakening prevents a morning surge in hypertensive patients. Case report of three cases

Although the blood pressure-lowering action of some long-acting calcium antagonists may last more than 24 h, some patients taking this drug still experience a morning surge, i.e. an early morning increase in blood pressure. We evaluated this morning surge in three hypertensive patients with morning surge after administration of antihypertensive drugs including nifedipine CR. Nifedipine CR is one of the once-a-day formulations of nifedipine, which after administration, results in two peaks in the plasma concentration of nifedipine. The first concentration peak of occurs 3 h after administration and the second around 12 h after intake. When the time of intake of nifedipine CR was changed from after breakfast to immediately after awakening, the morning surge was suppressed in these patients without the use of other drugs such as alpha- or beta-blockers. Administration of nifedipine CR immediately after awakening is one option that can be used to prevent morning surge as well as to control blood pressure throughout the day.

Thromboembolic Complication in Atrial Fibrillation in a Long-Term FolIow-Up

The incidence of thromboembolic complications among 288 patients with atrial fibrillation (AF) who were followed up during an average period of 7.2 years was examined retrospectively. The annual incidence of thromboembolic complications was 1.6% in total, 1.7% in valvular heart disease (n=128), and 2.1% in non-valvular heart disease (n=117). No thromboembolism occurred in lone AF (n=43), defined as the complete absence of any underlying disease. The type of AF before embolic attack was chronic in 26 cases and paroxysmal in 6 cases. The cardiac rhythm at the time of the embolic attack was AF, except in 2 cases in which ECG was not recorded. In all patients with thromboembolic complications who were receiving antithrombotic therapy during the follow-up, the anticoagulant effect just before the embolic attack was found to be insufficient. Major bleeding was not observed in the patients receiving antithrombotic therapy. Thromboembolism in AF in long-term follow-up tends to occur more frequently in patients with underlying heart disease and in those with chronic AF compared rather than paroxysmal AF; it rarely occurs in lone AF. We should not hesitate to administer sufficient anticoagulant therapy in AF patients who are at high risk of developing thromboembolic complications. (Jpn Circ J 1998; 62: 255 - 260)

The clinical and pathological study in the recurrent myocardial infarction

老年者心筋梗塞例を対象として, 再梗塞を起こした例とそうでない例とを臨床的 (再梗塞を起こした心筋梗塞例53例, 平均74歳, 一回梗塞例64例, 平均74歳) および病理学的 (生前2回以上梗塞を繰り返した剖検例64例, 平均78歳, 一回梗塞例232例, 平均79歳) に比較検討した.梗塞部位別では, 再梗塞時には心内膜下梗塞の比率が多い傾向が認められた. 梗塞急性期の血行動態は, 再梗塞例ではCPK最高値で表した梗塞量は小さいが, 初回梗塞と合わせるとより強い心ポンプ機能の低下をきたした. また初回梗塞と再梗塞とで梗塞部位が異なる例では, 同部位例より悪い血行動態を示した. 慢性期における主な薬剤の使用率には両群で有意差は認められなかった. 再梗塞例の初回梗塞後に出現した狭心症の頻度は60%に達し, 同時期の一回梗塞例と比較すると有意に高い出現率を示した(χ2=17.5, p<0.01). 初回梗塞後に存在した冠疾患危険因子のうち, 高血圧では再梗塞例の方が有意に高い存在率を示した (χ2=6.13, p<0.05). 各危険因子の個数の和の合計を総のべ数で表すと, 初回梗塞後では再梗塞例の方が有意に高い数値を示した (χ2=10.36, p<0.01).剖検所見による梗塞サイズでは, 再梗塞64例中52例 (81.3%) は梗塞長径5cm以上の大梗塞で占められた. また, 再梗塞例では冠動脈狭窄指数で表した狭窄度が強く, その62.5%は3枝病変であった.以上より, 心筋梗塞患者の予後を考える上で再梗塞の予防は重要な課題であり, そのために梗塞後狭心症の防止や高血圧をはじめとする危険因子の是正にはとくに留意する必要があると思われる.