Hiroichiro Yamaguchi

Myocardial recovery during post-ischemic reperfusion: Optimal concentrations of Na+ and Ca2+ in the reperfusate and protective effects of amiloride added to cardioplegic solution

SummaryThe effects of Na+ and Ca2+ concentrations in the reperfusate on post-ischemic myocardial recovery were examined. Also, the myocardial protective effects of amiloride, an inhibitor of the Na+/Ca2+ and Na+/H+ exchange systems, added to cardioplegic solutions were assessed, using an isolated working rat heart perfusion system. Global myocardial ischemia was induced by 30-min normothermic cardioplegic arrest, using St. Thomas’ solution. The concentration of Na+ in the reperfusate varied, stepwise, from 75 to 145 mM/l, and that of Ca2+, from 0.1 to 2.5 mM/l. In this study post-ischemic functional recovery was best at 110 mM/l Na+ and 1.2–1.8 mM/l Ca2+ in the reperfusate. A significantly greater postischemic functional recovery and a lower creatine kinase release were observed when amiloride was added to the cardioplegic solution. Ca2+ overload via Na+/Ca2+ and Na+/H+ exchange systems would, thus, appear to be due, at least in part, to post-ischemic reperfusion injury.

CORRELATION BETWEEN CEREBRAL OXYGEN METABOLISM AND CEREBRAL BLOOD FLOW SIMULTANEOUSLY MEASURED BEFORE AND AFTER ACETAZOLAMIDE ADMINISTRATION

The cerebral circulation and metabolism of ten preoperative cardiac surgery patients were assessed. Alterations in regional cerebral blood flow (rCBF), measured by 123I-N-isopropyl-p-iodo-amphetamine single-photon emission computed tomography, and in cerebral oxygen metabolism, simultaneously detected by near-infrared spectroscopy (NIRS) before and after acetazolamide administration, were investigated. The rCBF (ml/min/100 g) increased significantly from 40.21±7.65 to 56.24±13.69(p<0.001), and a significant increase in oxyhemoglobin (Oxy-Hb) of 13.9% (p=0.0022) and total hemoglobin (Total-Hb) of 5.7% (0.0047) along with a significant decrease in deoxyhemoglobin (Deoxy-Hb) of 8.9% (p=0.0414) were observed concomitantly. Thus, the Oxy-Hb/Total-Hb ratio (%Oxy-Hb) rose significantly from 67.26±9.82% to 72.98±8.09%(p=0.0022). Examination of the relationships between individual parameters showed that the percentage changes in rCBF and Oxy-Hb were significantly correlated (r=0.758,p=0.011). The percentage changes in rCBF and %Oxy-Hb were also correlated significantly (r=0.740,p=0.014). In conclusion, this evidence suggested that NIRS is able to detect relative changes in cerebral hemodynamics and reflect luxury perfusion induced by acetazolamide.

The role of low-density lipoprotein apheresis as postoperative care of bypass grafting for chronic arterial occlusion

Since November 1989, low-density lipoprotein apheresis has been applied to patients with intractable hyperlipidaemia following bypass grafting for chronic arterial occlusion of the lower extremities. The treatment group comprised six patients (four men, two women) with arteriosclerosis obliterans. In five patients, the ankle pressure index deteriorated and intermittent claudication recurred due to atherosclerotic progression. Results of low-density lipoprotein apheresis were dramatic; the deteriorated ankle pressure index and intermittent claudication improved significantly after several applications of low-density lipoprotein apheresis. Significant angiographic improvement was obtained in two patients. It is concluded that low-density lipoprotein apheresis appears to be an efficient method to preserve graft patency and treat postoperative patients with deteriorated ankle pressure index.

A Case of Popliteal Artery Aneurysm Associated with Popliteal Artery Entrapment Syndrome

Popliteal artery entrapment (PAE) is an uncommon syndrome. Although this phenomenon can cause claudication in younger populations, other clinical features may vary. The present report describes a case of a 48-year-old woman who was referred for treatment of a pulsatile mass in the right popliteal fossa. Computed tomography scan and magnetic resonance imaging demonstrated popliteal aneurysm associated with PAE. Resection of abnormal musculotendinous structures, aneurysmectomy and subsequent revascularization were successfully performed. Although PAE may lead to poststenotic dilatation and aneurysm formation, huge aneurysm without clinical signs of ischemia in a patient with PAE is extremely rare.Popliteal artery entrapment (PAE) is an uncommon syndrome. Although this phenomenon can cause claudication in younger populations, other clinical features may vary. The present report describes a case of a 48-year-old woman who was referred for treatment of a pulsatile mass in the right popliteal fossa. Computed tomography scan and magnetic resonance imaging demonstrated popliteal aneurysm associated with PAE. Resection of abnormal musculotendinous structures, aneurysmectomy and subsequent revascularization were successfully performed. Although PAE may lead to poststenotic dilatation and aneurysm formation, huge aneurysm without clinical signs of ischemia in a patient with PAE is extremely rare.

Risk factors for disordered cerebral autoregulation during hypothermic cardiopulmonary bypass

Disordered cerebral autoregulation during cardiopulmonary bypass (CPB) is regarded as one of the causes of neurological dysfunction after cardiac surgery. However, little documentation of risk factors associated with cerebral autoregulation during CPB has been reported. Sixty consecutive patients undergoing coronary artery bypass were classified into subgroups according to whether they had preoperative cerebrovascular disease (CVD), hypertension (HT), or diabetes (DM). Cerebral oxygenation was monitored by jugular venous bulb oxygen saturation (SjvO2) and near-infrared spectroscopy parameter (%Oxy-Hb) during the operation, and the relationships between these values and intraoperative parameters were evaluated. The results showed that SjvO2 and %Oxy-Hb in the CVD+group were lower than in the CVD-group. Multiple stepwise regression analysis on SjvO2 and %Oxy-Hb in the CVD+ group revealed that only MAP was a predictive factor and that there was a positive correlation between MAP and both SjvO2 and %Oxy-Hb (r=.651,r=.693, respectively,P<0.0001). The coexistence of HT and DM increased the strength of the correlation between MAP and SjvO2 (r=.863,p<0.0001) PaCO2 was the predictive factor in the CVD- group. A positive correlation was found with SjvO2 (r=.458,P>0.0001), and the correlation was stronger in patients without any risk factors (r=.671,P=0.0001). The results suggested that patients with CVD, HT, and DM may experience failure of cerebral pressureflow autoregulation and cerebrovascular reactivity during CPB.

A case of antiarrhythmic agent-induced atrioventricular and intraventricular conduction disturbance in chronic hemodialysis patients after CABG

抗不整脈剤であるpilsicainide hydrochlorideの催不整脈作用により房室および心室内刺激伝導障害を起こした1例を経験し, 血液吸着および血液透析による同剤の除去効果についての知見を得たので報告する. 症例は57歳男性, 慢性腎不全に対して血液透析中であったが, 不安定狭心症のため冠動脈バイパス術を施行した. 術後心室性期外収縮に対しmexilletine, disopyramideを使用したが効果がなく, pilsicainide hydrochloride (150mg) を開始した. 不整脈は消失したが, 開始後5日目に突然心電図変化 (PQ延長, QRS幅の増大) が出現し, pilsicainide hydrochlorideの催不整脈作用による房室および心室内刺激伝導障害と診断した. 投薬を中止するとともに緊急の血液吸着と血液透析を施行し, 血中濃度 (有効血中濃度: 0.2-0.9μg/ml) は4.74μg/mlから3.96μg/mlまで減少した. その後合計6回の血液透析を施行し, 発症後14日目の透析後の血中濃度は0.38μg/mlまで減少した. 心電図変化も改善し, 血中濃度と心電図上のPQ時間, QRS幅との間には有意な相関を認めた. Pilsicainide hydrochlorideに対する血液吸着および6回の透析による平均除去率はそれぞれ13.7%, 23.9%で開始後120分でのクリアランスはそれぞれ37.6ml/min, 84.1ml/minであった. また膜前後の血中濃度差から算出した実際の除去量は血液吸着では31mg, 4回目の透析時は8.3mgであり, 各時点における循環血液中の含有量をほぼ除去できたと判断された.