Takafumi Hamasaki

Effect of magnesium and calcium on myocafdial protection by cardioplegic solutions

The cardioprotective effect of the magnesium and calcium content of hyperkalemic cardioplegic solutions was investigated using isolated rat hearts subjected to hypothermic ischemic arrest. Hearts were arrested for 180 minutes at 20 degrees C by administering a 3-minute infusion of cardioplegic solution containing various concentrations of magnesium and calcium. Treatment groups received solution with either 0, 8, or 16 mmol/L magnesium. For each of these magnesium concentrations, 0.1, 0.6, or 1.2 mmol/L calcium was also present in the solution. At each concentration of magnesium, the percentage recovery of aortic flow was dependent on the calcium concentration. The maximum percentage recovery of aortic flow was 67.9% +/- 2.3% (mean +/- standard error of the mean) in the Mg-free, 0.1 mmol/L Ca group, whereas it was 65.1% +/- 2.7% in the 8 mmol/L Mg, 0.1 mmol/L Ca group and 70.0% +/- 3.5% in the 16 mmol/L Mg, 0.6 mmol/L Ca group. No significant differences in the recovery of cardiac function and creatine kinase leakage were observed between the three groups. The findings suggested that the cardioprotective effect was dependent on the relative concentration of both magnesium and calcium, and that it is important to maintain an appropriate ionic balance in cardioplegic solutions.

Temperature Dependency of Calcium-Induced Reperfusion Injury in the Isolated Rat Heart

The temperature dependence of Ca-induced reperfusion injury was studied in an isolated rat heart preparation. Hearts were subjected to 90 minutes of hypothermic arrest (20 degrees C) followed by 15 minutes of reperfusion at 20, 28, or 37 degrees C with a reperfusate containing various concentrations of Ca (0.1-2.55 mM). When reperfusion was started at 37 degrees C, the Ca concentration in the reperfusate significantly affected both postischemic functional recovery and creatine kinase leakage. Bell-shaped dose-response curves were observed. The optimal Ca concentration for 37 degrees C reperfusion was between 0.3 and 0.7 mM. When reperfusion was started at 20 degrees C, neither functional recovery nor creatine kinase leakage was dependent on the Ca concentration in the reperfusate. At 28 degrees C, functional recovery was not dependent on the Ca concentration, however, creatine kinase leakage was. These results indicate that Ca-induced reperfusion injury depends on the temperature of the reperfusate and that the boundary temperature of the reperfusate at which Ca-induced reperfusion injury becomes manifest seems to be near 28 degrees C.

Endovascular Treatment of Left Subclavian Artery Pseudoaneurysm after Clavicle Fracture in an Elderly Adult with a 40-Year History of Behçet’s Disease

Behçets disease (BD) is a rare chronic systemic vasculitis of unknown etiology that presents in young adults. We report a very rare case of a left subclavian artery pseudoaneurysm identified after a left clavicle fracture in a 70-year-old man with a 40-year history of intestinal BD. The patient received fixation by banding to treat a fracture after falling from a bed about 5 months previously, and he was referred to our hospital due to the finding of a left subclavian pulsatile mass. As enhanced computed tomography showed a left subclavian artery pseudoaneurysm, it was repaired using an endovascular stent graft.

Effects of Calcium in Continuous Cardioplegia on Myocardial Protection

The effects of calcium (Ca) on a hyperkalemic cardioplegic solution for continuous cardioplegia were examined in an isolated perfused working rat heart model. The coronary arteries were perfused with a modified Krebs-Henseleit bicarbonate buffer (K-H) solution, containing various concentrations of Ca(0.1, 0.6, 1.2, and 2.5 mmol/l) and a high concentration of potassium (20 mmol/l), for 180 min, after which cardiac arrest was induced at 37°C for 180 min. Cardiac function and creatine kinase (CK) were measured. In the control group, K-H solution was infused in place of the cardioplegic solution, and cardiac arrest was not induced. No significant differences were observed between the groups infused with the K-H solution containing Ca concentrations of 0.6, 1.2, and 2.5 mmol/l in the percent recovery of aortic flow (82.1±2.9%, 80.6±2.0%, and 71.5±3.7% (mean±SEM) respectively) or in the recovery of other indices of cardiac function, or in CK leakage. There were also no significant differences in the recovery of cardiac function and CK leakage between these groups and the control group. In the Ca 0.1 mmol/l group, however, the characteristic Ca paradox was observed. These findings suggest that if the Ca concentration in a cardioplegic solution is higher than 0.6 mmol/l during continuous cardioplegia, excellent cardioprotective effects will be achieved.

A Case of True Brachial Artery Aneurysm with Severe Left Upper Limb Ischemia

Brachial artery (BA) aneurysms are rare, and most are false aneurysms. Although true BA aneurysms have been reported, most have been reported without symptoms. A 65-year-old man was referred due to a left upper limb mass with rest pain and slight ulceration of the left second and third fingers. As enhanced computed tomography revealed the patency of only the left proximal and distal BA as well as the thrombosed mass, excision of the aneurysm and BA replacement were performed with a great saphenous vein graft. The postoperative course was uneventful, and the rest pain and ulceration were resolved.

Revascularization for acute blunt popliteal artery injury

A 45‐year‐old man was brought to our hospital in pre‐shock after falling from a motorcycle. As we diagnosed him with open fracture of the right femur with leg ischemia, we performed revascularization of injured popliteal artery and treated the leg. The pathological findings showed fragmentation and decrease of elastic fibers and fragmentation of collagen fibers, but no inflammatory cells or intimal hyperplasia, and no dissection.

A Case of Heparin-Induced Thrombocytopenia Type 2 after Repair of Juxtarenal Abdominal Aortic Aneurysm

Heparin-induced thrombocytopenia (HIT) is still a relatively uncommon condition and it is not well known how to administer argatroban during continuous hemodiafiltration (CHDF). A 72-year-old man required CHDF with heparin because of the oliguria and hyperpotassemia directly after the open repair of a juxtarenal abdominal aortic aneurysm. As the postoperative blood platelet count dropped and there was a thrombus in the CHDF circuit, HIT was suspected and nafamostat mesilate, but not heparin, was immediately administered for CHDF. As heparin-platelet factor 4 complex was positive, we diagnosed him with HIT and started argatroban while monitoring the activated clotting time (ACT), resulting in no further obstruction of the CHDF and an increase in the platelets. There was no disadvantage for administering nafamostat mesilate which we have commonly used instead of heparin, we should have used argatroban once we suspected HIT. It may be important to consider the history of heparin especially in administering heparin and it may be useful to monitor the ACT when initially starting argatroban for patients with HIT.