Yasuhiro Nishikawa

A rapid-cross-sectioning and freeze-clamping device for the beating canine heart

A new sampling method of cross-sectioning the canine heart in situ was developed. A mechanical device, driven by spring power, enabled cross-sectioning of a short-axis plane of the beating canine heart (4 mm thick) with high speed rotating blades, at a pre-determined phase of the cardiac cycle, and instantaneous freeze-clamping (2.4 mm thick) with pre-cooled aluminum blocks, all within 120 ms. By this method, the anatomical structures of the sample were well preserved. Transmural metabolism and flow distribution were instantaneously fixed and high resolution of the two-dimensional redox state was obtained by application of NADH fluorescence photography. Micro-samplings from the desired portion of the cross-sectional slice were possible at -190 degrees C. NADH fluorescence of the samples did not increase from the surface to 1.2 mm in depth, confirming that there was no ischemic artifact. With the present technique, a heart sample in which transmural metabolism, and the redox state, are fixed and visualized is attainable, thus providing a new tool for the study of myocardial ischemia.

Variations in myocardial contraction sequence under various hypoxic conditions

SummaryHypokinetic myocardial segment motion is observed in various pathophysiologic conditions. The aim of this study was to clarify the mechanisms involved in differences in segment motion of hypokinesis. Nineteen open-chest dogs were studied with regard to myocardial segment length, left ventricular pressure, and internal minor-axis diameter. Sequential instantaneous myocardial elastance [α(t) curve] was calculated under 4 different hypoxic conditions: complete coronary occlusion and reperfusion, partial coronary occlusion, coronary microembolization, and anoxic perfusion. The α(t) curve peaked at end-systole in the case of normal contraction; but it was almost totally flat when complete bulging occurred. The hypokinesis which occurred during development of the complete systolic bulgc immediately after complete coronary occlusion had an earlier α(t) peak curve than the hypokinesis resulting from partial coronary stenosis (209.5 ± 35.6 ms after end-diastole vs. 261.9 ± 18.2 ms; p < 0.02), microsphere injection into the coronary artery (243.2 ± 24.5 ms vs. 289.3 ± 15.4 ms; p < 0.05), or anoxic perfusion (213.4 ± 40.2 vs. 275.6 ± 28.3 ms; p < 0.05). The early a(t) peak resulted in a late-systolic bulge in segment length motion. In conclusion, hypokinetic segment motion differed depending on whether the coronary blood flow was present or not. A late-systolic bulge only developed immediately after complete coronary occlusion, and resulted from an abrupt decrease in myocardial stiffness during the cardiac cycle, which is closely related to the abrupt cessation of coronary blood flow.

Two cases of idiopathic restrictive cardiomyopathy

概 要 拘 束型心 筋症は ア ミロイ ドーシ スな どに伴 うものが多 く,特 発性 の もの は まれ であ る. 今回我 々は特発性 の2例 を経 験 した.心 臓 カテ ーテル検 査な どでは収縮性 心膜炎 に類似 した病 態がみ られたた め心膜切除 術 を施 行 した.症 例1. 31才,女 性.17才 よ り息 切れ が出現 し,21才 時MSと して交連切 開術 を受けて いる,心 エ コー図上,心 膜の肥厚 を認め た.症 例2. 46才,女 性.1年 前 よ り心 膜液貯留 と右心不 全症状 が出現 した.心 臓 カテ ーテ ル検 査で は両例 ともに右 心室拡張 寒期圧 の上昇 を認 め,左 右 の心室圧 は拡張期 はほぼ 等 しく,圧 波形 はdip and plateau を呈 した.術 中所 見で は2例 とも心膜 の肥厚,癒 着は軽度 であつ た.術 後 も術前 と同様 の血行 動態が持続 し,自 覚症状 は改善 しなかつた,心 筋生検 に よ リア ミロイ ドー シスな ど明 らか な病 因は否定 された.拘 束型心 筋症,収 縮 性心膜 炎の臨床的鑑別 が 困難 な場合 もある ことを報告す る.