• 作者： 謝凱生; 張嘉侃; 張國柱; 陳幸一
• 作者服務機構： 台北榮民總醫院小兒部; 國防醫學院及三軍總醫院小兒學科; 台灣大學電機工程研究所; 國防醫學院生理學科及醫學研究部
• 中文摘要： 目前臨床上已可用杜卜勒超音波心圖測量主動脈最高血流速度（PV）及其最大及加速度（MA）以測定左心室功能，然而其受心臟負荷因素之影響仍有待探討。 本研究即在評估PV與MA受左心室負荷之影響程度。本研究以八隻貓實驗動物，麻醉後置於動物手術檯上，經左側開胸術，將電磁血流計置於升主動脈近端以記錄PV及MA。經由靜脈注射Dobutamine（DT），Angiotensin（AII）及Dextran（DN） ,以分別改變心臟收縮力，後負荷及前負荷。在穩定狀態下，DT使PV由56±9增至78±14 cm/sec（P<0.05），MA則由1302±108 cm/sec2增至1644±117 cm/sec2（P<0.05）。經由All使後負荷增加時，PV由60±17減至55±6 cm/sec（P<0.05），而MA則由1219±109降至1099±109cm/sec2（P<0.05），DN之靜脈快速輸注，因心臟前負荷增加，使PV急速由48±7升至82±13cm/sec（P<0.05），MA則由1089±95cm/sec2增加至1604±109cm/sec2（P<0.05）。 本研究結果顯示PV及MA均可充分反映心臟收縮力之改變；然而PV及MA亦均受前負荷之明顯影響。後負荷之增加亦均使PV及MA呈較少，但仍有意義的改變。綜合言之，MA較PV受前後負荷之影響較小，故在臨床上應用PV及MA做為心室功能指標時，應注意心臟前後負荷情況之改變，以作正確之判讀。
• 英文摘要： Aortic flow measurement with Doppler echocardiography has become a non-invasive technique inclinical practice. In the present animal study, we evaluated the flow-derived parameters such as peak velo-city (PV) and its maximal acceleration (MA) as indices of ventricular contractility independent of theloading status. Eight pentobarbital-anesthetized cats were maintained with artificial ventilation. The chestwas opened to place an electromagnetic flow probe around the ascending aorta for recording pulsatileaortic flow. PV and MA were measured from the flow tracing and on-line electronic differentiation. Intra-venous infusions of dobutamine (DT), angiotensin II (All) and dextran (DN) were used to alter the cardiacinotropism, afterload and preload, respectively. At a steady state (approximately 5 min after infusion),DT increased the PV from 56 ± 9 to 78 ± 14 cm/sec (p<0.05) and MA from 1302 ± 108 to 1699 ± 117cm/sec (p<0.05). In response to All infusion, PV was slightly reduced (60 ± 7 to 55 ± 6 cm/sec, p<0.05) while MA was also reduced mildly but significantly (1219 ± 109 to 1099 ± 109 cm/sec , p<0.05).Dextran infusion produced a marked increase in PV (48 ± 7 to 82 ± 13 cm/sec, p<0.05) while the increasewas slightly less for MA (1089 ± 95 to 1604 ± 109 cm/sec). The results indicated that inotropic stimula-tion markedly increased both PV and MA. PV and MA responded slightly but significantly to afterloadalterations. (8.3% vs 9.8%, respectively). Both PV and MA increased markedly to the preload increment.Although MA showed the same mild degree of depression with afterload augmentation, its response to pre-load challenge was less than PV (41% vs 71% increase, respectively). MA may be a better index for leftventricular contractility than is PV, but careful consideration of the loading status should be taken beforeadopting these parameters into clinical practice.
• 中文關鍵字： aortic flow velocity; maximal acceleration; contractility; preload; afterload.
• 英文關鍵字： --