Estrogen affects vascular tone differently according to vasoactive substances in ovariectomized Sprague-Dawley rat

The favorable effects of estrogen on cardiovascular diseases can be explained by several mechanisms such as changes in serum lipid profiles and thrombogenecity. Estrogen also affects the vascular tone, but there has been no report in which the effect of estrogen was tested comprehensively for several vasoactive substances, especially after long-term administration. Two weeks after bilateral ovariectomy in 8-week old female Sprague-Dawley rats, placebo or 17 beta-estradiol (E2) pellets (0.5 mg; released over 3 weeks) were implanted subcutaneously. Two weeks after pellet implantation, organ chamber experiments were performed using aortae. Compared with control, E2-treated vessels showed impaired endothelium-dependent relaxation to acetylcholine. E2 enhanced the contraction to norepinephrine and U46619 and had no effect on endothelin-1-induced contraction. In contrast, the contraction to angiotensin (AT)-II was inhibited by E2. Northern blot analysis for AT1 receptor expression using cultured aortic smooth muscle cells showed no difference between control and E2-treated cells, suggesting that AT1 receptor downregulation is not the likely mechanism. These results suggest that E2 affects the vascular tone variably according to vasoactive substances.

Operations for Descending Thoracic Aortic Aneurysms Utilizing the Antithrombotic Cardiopulmonary Bypass / 日本心臓血管外科学会雑誌

Fifteen consecutive patients with true or dissecting aneurysms of the thoracic descending aorta, and thoraco-abdominal aorta were operated upon under left thoracotomy with the support of partial cardiopulmonary bypass, equipment composed of a membrane oxygenator, centrifugal pump, and percutaneous thin wall cannulae which were all coated with covalently bonded heparin. The polyvinyl tube was coated with Biomate. The administration of systemic heparin was determined by an ACT of around 200 seconds. One perioperative death in a case treated by emergency operation for a ruptured descending aortic aneurysm occurred due to acute myocardial infarction. Other patients tolerated their operation well and are alive. No thromboembolic accident, bleeding tendency, nor organ failure were observed postoperatively in any other patients. In conclusion, the cardiopulmonary bypass using an antithrombotic circuit is safe and recommendable for thoracic descending or thoraco-abdominal aneurysm operations.

Surgical Treatment of Abdominal Aortic Aneurysm in Cases with Previous Laparotomies / 日本心臓血管外科学会雑誌

From January 1987 to October 1992, 60 consecutive patients operated on for infrarenal abdominal aortic aneurysm (AAA) were reviewed to evaluate the effect of previous laparotomies giving on the results of aneurysmal surgery. Eleven of 60 patients had previous laparotomies. Two of them required emergency operation for ruptured aneurysms. One of them died during surgery as a result of excessive hemorrhage prior to cross-clamping the aorta. Severe peritoneal adhesion had made if difficult to properly expose the aorta for cross-clamping to control hemorrhage. There were no statistical significance in mortality between the previous laparotomy and non-laparotomy groups. Excluding ruptured cases, we compared the previous laparotomy group (9 patients) and non-laparotomy group (37 patients) with reference to perioperative factors, including operation time, blood loss, non-oral feeding days, bed-ridden days, and hospital stay but there were no statistically significant differences. These results suggested that previous laparotomy is not a serious risk factor in operations for AAA.