The Role of Myocardial Gap Junction in Ischemia-Reperfusion Injury in Senescent Rabbit Myocardium / 日本心臓血管外科学会雑誌

Objective. We investigated whether the aging-related decrease in gap junction expression affects myocardial response against ischemia-reperfusion injury of the rabbit myocardium. Methods. Isolated aged (≥135 weeks) or mature (15-20 weeks) rabbit hearts were perfused with Krebs-Henseleit solution via a Langendorff apparatus, and were divided into five groups as follows: 7 mature hearts served as mature controls (Group A), 7 mature hearts underwent ischemic preconditioning (IPC) consisting of two cycles of global ischemia for 5min followed by reperfusion for 5min (Group B), 7 aged hearts served as aged control (Group C), 7 aged hearts underwent IPC (Group D) and 7 mature hearts received 1mM of gap junction uncoupler heptanol for 5min (Group E). Then, all hearts were subjected to 1h of left anterior descending coronary artery occlusion followed by 1h of reperfusion. Left ventricular pressure, ischemic zone monophasic action potential and coronary flow were measured throughout the experiment and the infarct size (IS) was determined at the end of the experiment. Gap junction expression was investigated by the electron microscopy. Results. The IS of Group A was 39.1±3.8 (%) and that of Group B was 26.9±3.8 (%)^* (^*<i>p</i><0.05 vs. Group A). The IS of Group C was 19.3± 1.6(%)^*. That of Group D was 43.6±5.8 (%)^# (^#<i>p</i><0.05 vs. Group C). IS of Group E was 24.3±1.6 (%)^*. Electron microscopic findings demonstrated that gap junction expression in aged hearts was less prominent than in mature ones. Conclusion. These data suggested that aged myocardium might be more tolerant of ischemic insult than that of mature heart, and that the mechanism might be related to the aging-related change of gap junction expression.

Emergency Surgical Management of Infective Endocarditis in Two Pregnant Cases / 日本心臓血管外科学会雑誌

We report two emergency mitral valve replacements performed successfully on 16-week and 29-week pregnant women for infective endocarditis in the active phase. The first patient was in severe acute heart failure on admission, and the fetus was already dead. Induced abortion was performed uneventfully 6 days after mitral valve replacement. The second patient presented with several episodes of systemic embolization. An echocardiography revealed giant movable vegetation on the mitral valve. The patient had emergency mitral valve replacement just after the Caesarian section. Both the patient and her baby weighting 1, 374g had an uneventful good courses with no complication. We concluded that in emergency operations in pregnancy, saving the mother's life should have priority over all else, but we should find the way to rescue the fetus life if at all possible. Therefore, depending on the situation, we should not hesitate about doing a simultaneous operation, Caesarian section and heart surgery, for that purpose.

Appropriate Protamine Administration to Neutralize Heparin after Cardiopulmonary Bypass Using the Hepcon/HMS / 日本心臓血管外科学会雑誌

We reevaluated our heparin and protamine administration protocol during and after cardiopulmonary bypass (CPB). In 12 patients who underwent cardiac surgery using a heparin-coated circuit under mild hypothermia, heparin concentration was measured with the Hepcon^®/HMS. Before initiating CPB, 1.5mg/kg of heparin was given to maintain the activated clotting time (ACT) at more than 400sec. Patients were divided into two groups. In group I (<i>n</i>=6), heparin was neutralized with an empirical dose of protamine (1.5mg protamine/mg initial heparin). In group II (<i>n</i>=6), the protamine dose was determined by the residual heparin concentration, measured with the Hepcon^®. Patients in group II received a lower dosage of protamine than group I (1.7±0.0 vs. 3.6±0.4mg/kg, <i>p</i><0.001). There were no significant differences in the intraoperative bleeding, postoperative bleeding and activated clotting time between the groups. By determining the appropriate protamine dosage, this heparin analysis system may be useful in managing CPB.

Thrombolysis for Bileaflet Valve Thrombosis / 日本心臓血管外科学会雑誌

Between January 1981 and December 1996, we performed valve replacement in 281 patients using bileaflet prosthetic valves in mitral and/or tricuspid positions. Thrombosed valve were seen in 10 patients (7 in mitral, 3 in tricuspid positions). In 5 patients, coumadin had been stopped for several reasons (pacemaker implantation, melena, drug allergy), but in the other 5 patients, anticoagulation was within the therapeutic range at the time of presentation. For thrombolytic therapy urokinase or tissue plasminogen activator were used. The treatment was successful in 5 patients (4 mitral, 1 tricuspid), and unsuccessful in 5 patients (3 mitral, 2 tricuspid). Three of the 5 unsuccessful patients were treated surgically (3 with re-mitral valve replacement, 1 with thrombectomy). Prompt surgical treatment can be used as the first line of therapy for thrombosed valves. Thrombolytic therapy may be useful in some cases of bileaflet valve thrombosis without critical hemodynamic collapse. Doppler echocardiographic assessment of increasing peak velocity and pressure half time is useful for detecting thrombosed valves.

Intrathoracic Prosthetic Graft Infection Caused by MRSA / 日本心臓血管外科学会雑誌

A 62-year-old woman, who received implantation of a prosthetic graft for treatment of a descending aortic aneurysm 15 months previously, was admitted with hemoptysis. An aortogram demonstrated communication from the distal anastomosis to S⁶ of the left lung. After removal of the aorta across the distal anastomosis concomitantly with left lower lobectomy, we replaced a short segment of the graft. Culture of the pus obtained from the anastomotic site was positive for MRSA. Postoperatively, although the left pleural cavity was irrigated continuously with 1% popidone iodine solution, massive bleeding from the distal anastomosis appeared again 2 weeks later. This time, to remove the infected graft as much as possible, two extraanatomical bypasses were created between the right axillary and right femoral arteries, and the ascending and abdominal aorta. The closed prosthetic and aortic stumps were covered by a viable omental flap. Four months later, bleeding occurred again at the site of the proximal anastomosis. The last radical surgery was performed extrapleurally through a trapdoor thoractomy made in the left infraclavicular region. There was a 1.5cm long laceration of the aorta just proximal to the oldest graft-aortic anastomosis. The aorta was divided and closed between the left common carotid and subclavian arteries. The left subclavian artery was ligated at its origin. The pleural cavity was continuously irrigated with popidone iodine to clean up the microorganisms. She was discharged from the hospital on the 258 POD and has been doing well since then.