Naoaki Takemoto

Primary aortoesophageal fistula secondary to thoracic aneurysm : Successful surgical treatment by extra-anatomic bypass grafting ()

Aortoesophageal fistula (AEF) secondary to thoracic aneurysm is rare, and is usually fatal without prompt surgical intervention, with few survivors reported. Here we report a case of a 68-year-old woman late-presenting AEF successfully treated by extra-anatomic bypass grafting. Since she had already a mediastinal infection caused by AEF on admission, we performed extra-anatomic bypass grafting from the ascending aorta to the infrarenal aorta, and primary esophageal repair. The extra-anatomic bypass grafting was performed to avoid the risk to secondary graft infection and to decrease the total ishemic time induced by intraoperative aortic clamping, which is necessary when in-situ graft replacement is chosen. Although only 17 cases (including the present case) have been reported as long-term survivors, most have involved in-situ repair of the thoracic aneurysm. To our knowledge, the present case was only the second treated successfully by extra-anatomic bypass grafting. We recommend extra-anatomic bypass grafting for a case with severe infection and prolonged hypoperfusion insult caused by massive bleeding due to rupture in an aneurysm.

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.

Risk of low calcium and high magnesium in continuous warm hyperkalemic cardioplegia

BACKGROUND The recent introduction of operations on a warm heart has prompted clinical reports on the usefulness of continuous blood cardioplegia, but no in-depth basic evaluation of continuous cardioplegia has been done. The cardioprotective effects of magnesium (Mg) and calcium (Ca) in continuous warm hyperkalemic crystalloid cardioplegic solutions were investigated in an isolated rat heart model. METHODS Isolated rat hearts were arrested for 180 minutes at 37 degrees C with a continuous warm hyperkalemic (20 mmol/L) modified Krebs-Henseleit bicarbonate buffer solution containing 1.2, 8.0, or 16.0 mmol/L of Mg and 0.1 to 2.5 mmol/L of Ca in different concentrations. Recovery of cardiac function and tissue damage were estimated. RESULTS For each Mg concentration, the percentage recovery of aortic flow generated dose-response curves depending on Ca concentration. However, as Mg concentration increased, the recovery of aortic flow decreased in the groups with 0.5 mmol/L of Ca or less. CONCLUSIONS In continuous warm cardioplegia the combination of low Ca and high Mg concentration caused severe cardiac injury, and normal Ca concentration avoids cardiac injury regardless of Mg concentrations.

The advantages of normocalcemic continuous warm cardioplegia over low calcemic cardioplegia in myocardial protection

The effects of changing the calcium content of a continuous warm hyperkalemic crystalloid cardioplegia (CWCP) were investigated in an isolated rat heart preparation. The hearts were divided into eight groups of six each. A control group consisted of fresh nonarrested hearts and the remaining seven groups consisted of hearts perfused with continuous hyperkalemic (20 mM) modified Krebs-Henseleit bicarbonate buffer solution with calcium concentrations of 0.1, 0.3, 0.5, 1.0, 1.5, 2.0, or 2.5 mM, for either 180 or 240 min at 37°C. In the hearts arrested for 180 min, there were no significant differences in postarrest cardiac functions between the control group and any of the groups perfused with calcium concentrations of 0.5 mM or more. With a calcium concentration of 0.1 mM, the calcium paradox was provoked. The change in the calcium content of CWCP perfused for 240 min significantly affected myocardial protection. Maximum aortic flow recovery, of 74.5%±2.7%, and minimum CK release, of 15.7±2.4IU/15 min/g dry weight, were observed in hearts perfused with a calcium concentration of 1.5 mM. The calcium paradox occurred even at a calcium concentration of 0.3 mM; therefore, normal calcium concentrations should be maintained in cardiac surgery to prevent cardiac injury.

Pulmonary artery aneurysm

Main pulmonary artery aneurysm is an exceedingly rare entity. We present a case of main pulmonary artery aneurysm with patent ductus arteriosus in a sixty-year-old woman. The aneurysm was successfully treated with aneurysmectomy and primary anastomosis of the defect of the main pulmonary artery, and the patent ductus arteriosus was divided. The etiology, operative indication and surgical intervention of main pulmonary artery aneurysm are discussed along with a review of the literature.

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.