胸部外科

We herein present the early and mid-term outcomes of therapeutic strategies for acute type A aortic dissection in our department. Subjects were 75 patients who were admitted to our department from January 2001 to October 2006. A total of 33 patients had thrombosed dissection;emergent surgery was indicated for cases in which the maximal ascending aortic diameter was ≧50 mm or when ulcer-like projection(ULP)was observed in the ascending aorta. Only 1 case of rupture-related death was observed, in a patient who had a maximal ascending aortic diameter of 52 mm and refused surgery. Although 8 patients were converted to surgery during the chronic phase, elective surgery was recommended in all cases. Surgery consisted of entry resection using open distal anastomosis under circulatory arrest at a bladder temperature of 25℃ , with antegrade cerebral perfusion into the 3 cervical branches of arch aorta based on bilateral axillary artery. In-hospital mortality of the 62 patients who underwent surgery was low(4.8%)and no dissection-related deaths were reported for the midterm outcomes. In addition, a low rate of cerebral infarction was observed among cases who had residual dissection of the brachiocephalic arteries after surgery. These findings demonstrate the validity of the therapeutic strategies in our department.

The purpose of this study was to assess the factors for clinical outcome of the surgical treatment of acute type A aortic dissection. From April 1996 to March 2006, 44 patients underwent emergency operation for acute type A dissection within 2 weeks from the onset. Resection of the intimal tear was performad with open distal anastomosis. The mean age was 63.4 (range 29-83) years, and 28 were female. As for their preoperative condition, 5 patients were in severe hemodynamic instability including cardiac arrest in 2, apnea in 1, and rupture in 4. Distal resection extended to ascending aorta in 24 patients (54.5%), hemiarch in 7(15.9%),and total arch in 13(29.5%).30-day mortality was 4.5% and the incidence of stroke was 13.6%. Several methods were used including axillary artery cannulation and central repair with adventitial inversion technique. Patients with malperfusions caused by acute type A dissection should undergo immediate aortic reconstruction by adequate circulatory assisting methods.

From November 1999 to December in 2005, 114 patients with acute type A aortic dissection underwent surgical treatment on an emergency basis. The overall in-hospital mortality was 7.9%(9 patients). Four were rupture cases before cardiopulmonary bypass. De novo postoperative stroke rate was 3.5%(4 patients). But all of them were discharged on foot. There were 6 rupture cases before operation. Unfortunately only 2 patients survived. Preoperative stroke due to malperfusion occurred in 19 cases(16.7%). Among them, those with clear consciousness had tendency to better social rehabilitation than those with drowsiness. We had experienced 2 vegetable states in the group of drowsiness after the operations. For better outcome, we must avoid rupture before operation and reconsider the timing of operation in the case of brain ischemia.

We evaluated the results of 213 emergency operations of acute type A aortic dissection in our center from January 2003 to December 2006. They were 101 male and 112 female, and the mean age was 64.6 years. The hospital mortality rate of all cases was 13.6%( 29/213). And that of cases with malperfusion was 31.9%(15/47). They consisted of stroke 8/17 (47.1%), myocardial ischemia 5/27 (18.5%) [right coronary artery:2/22( 9.1%), left main trunk:3/5( 60.0%)], and intestinal ischemia 2/3( 66.7%). The hospital mortality rate of pulseless electrical activity (PEA) cases was 57.1%(4/7), and that of aortic rupture cases was 33.3%( 3/9). On the other hand, the mortality rate of cases with cardiac tamponade alone was 4/45(8.9%).That of cases without cardiac tamponade and malperfusion was 3/105 (2.9%),and was significantly(p<0.05)lower than that with malperfusion.

The initial treatment for the thrombosed aortic dissection is still controversial. Accordingly, we sought to evaluate the strategy of its surgical repair. Ninety-six(35 type A and 61 type B)acute thrombosed aortic dissection were studied retrospectively. Initially all of them were treated medically. The ratio of the false and the true lumen(F/T ratio)was calculated on the onset. The uncontrollable cardiac tamponade, recanalization, large ulcer-like projection(ULP)and enlargement of the dissected aorta had a delayed surgical repair during the follow-up period. Eighteen of the type A and 14 of the type B were surgically treated and showed good result. The 1- and 5-year survival rates and the eventfree survival rates for the type A and the type B were almost equal with no statistical difference. The mean F/T ratio for the type A was 31% for the operative and 51% of the nonoperative cases( p=0.007).The maximum size of the initial aorta of the operative cases was larger than that in the nonoperative for the type B. The conservative therapy for the thrombosed aortic dissection decreased the number of the unnecessary operation and the strategy of the delayed surgical repair was justified properly.

In the treatment of acute type A aortic dissection, it is important to cope effectively with cerebral ischemia due to preoperative acute occlusion of arch branches and intraoperative cerebral malperfusion under extracorporeal circulation. The validity of our surgical strategy for such cases was evaluated. Our surgical strategies are as follow;for cases with preoperative cerebral infarction and disturbance of consciousness total aortic arch replacement is performed after the improvement of brain edema, and for cases of transient cerebral ischemia, emergency operation is performed. In the emergency operation, selective cerebral perfusion through the carotid artery of the diseased side is initiated as soon as possible. In conclusion, our surgical strategy for acute type A aortic dissection with cerebral ischemia due to acute occlusion of aortic arch branches is acceptable. There was no significant difference between the cerebral ischemia group and the control group concerning hospital mortality, cerebral complication and the 5-year survival rate.

Coronary malperfusion due to acute type A aortic dissection(DAA) is a lethal complication. It is especially difficult to rescue the patients with left coronary malperfusion because of acute global myocardial infarction(AMI),even with successful surgical treatments, including the replacement of the ascending aorta and coronary artery bypass grafting(CABG).We review our experience and illustrate our approach to these critically ill patients. In addition, we classify the mechanism of malperfusion into 4 types based upon perioperative findings and discuss surgical management indivisually. From January 1990 to April 2005, a total of 260 patients were operated for DAA in our institution. Twenty(7.7%) patients, 11 men and 9 women were suffering from coronary malperfusion due to DAA. The mean age was 55(range 28-72)years. The right coronary artery was involved in 9 patients, and the left in 11. All procedures such as graft replacement and CABG were done on an emergent or urgent basis. Hospital mortality rate of right coronary malperfusion was 22%(2/9 patients), and that related to left coronary malperfusion was 5/11(45%).Assisting device was required in 9 cases, venoarterial bypass(VAB) in 6 cases, left ventricular assist system(LVAS) in 1, left heart bypass(LHB)in 1, LHB+right heart bypass(RHB) in 1. We lost all patients using VAB. Only 3 patients supported with strong assist device survived. Aggressive myocardial resuscitation and early operation are the key factors in the management of these critically ill patients. But once severe myocardial infarction occurs, V-A bypass(percutaneous cardiopulmonary support) is useless in treating patients with DAA who develop severe heart failure. We recommend to implant stronger assist device including LVAS immediately before exacerbation of multiple organ failure. In conclusion, surgical management is not easy for emergency patients with DAA in association with myocardial ischemia. However, reasonable surgical results can be obtained with supplemental CABG and strong mechanical support of the left ventricle.

Nine patients, who suffered from acute type B aortic dissection with organ ischemia, were treated at our hospital from 2004 to 2006. Their mean age was 60.3(range 37-73)years. Eight of them required surgical intervention. Two patients with mesenteric ischemia underwent superior mesenteric artery(SMA) bypass surgery and their conditions were relieved. However, 1 of them died of aortic rupture 6 months later. One patient with celiac artery occlusion was at first treated nonsurgically, but was subjected to resection of the small intestine 3 weeks later because of ulcer perforation induced by ischemia. The other 5 patients with lower extremity ischemia underwent bypass surgery and were discharged. Conclusion:Bypass surgery is a reliable procedure for the treatment of acute type B aortic dissection with organ ischemia, allowing prompt resolution of ischemia.

Mesenteric ischemia is a dreaded complication of acute type A aortic dissection. From January 1994 to December 2004, 134 patients with acute type A aortic dissection were operated. Eleven patients showed postoperative mesenteric ischemia. Mortality of such patients was much higher than that without mesenteric ischemia(81.8 vs 10.6% , p<0.0001). Preoperative mesenteric and/or lower extremity ischemia were revealed to be the risk factors of postoperative mesenteric ischemia. Our strategy to manage these patients is as follows;patients who are suffering mesenteric and/or lower extremity ischemia preoperatively, or those whose computed tomography(CT)shows stenosis, obstruction, or dissection of the superior mesenteric artery, should be recognized as high-risk patients of postoperative mesenteric ischemia. Their mesenteric circulation should be examined directly with laparotomy after the central repair. If the mesenteric circulation seems to be suboptimal, iliac arterysuperior mesenteric artery bypass should be performed.

From June 2003 to November 2006, transapical aortic cannulation was performed in 73 patients(41 men and 32 women, mean age 63 years, 64 hemiarch repair and 9 total arch replacement)with acute type A aortic dissection. A 1-cm incision was made in the apex of the left ventricle, and a 7-mm soft and flexible cannula was passed through the apex and across the aortic valve until positioned in the ascending aorta under guidance by transesophageal echocardiography. In all cases, cardiopulmonary bypass flow was sufficient. There were no malperfusion events. Our results showed that transapical aortic cannulation was secure and useful for repair of acute type A aortic dissection.

Background:Malperfusion of vital organs is the most serious complication during cardiopulmonary bypass for acute aortic dissection. Method:From 2001 to 2006, 40 patients underwent operation for acute type A aortic dissection. Right brachial artery perfusion was performed in 20 patients. From May 2005, transesophageal echocardiography and cerebral oxygenation measured by near infrared spectroscopy were continuously monitored during operation. Results:There were 3 in-hospital deaths and 3 brain infarction. Switching of blood flow during cardiopulmonary bypass occurred in 3 patients;2 patients suffered from diffuse brain infarction while, in the other patient, switching of perfusion was detected at once by multi-monitoring and resolved by induction of right brachial artery perfusion. Conclusion:Close monitoring of cerebral oxygenation by near infrared spectroscopy, transesophageal echocardiography and right brachial artery perfusion are effective in operation for acute aortic dissection.

During the last 9 years, aortic root preservation using gelatin-resorcin-formalin (GRF) glue was performed in 63 patients as a part of surgery for acute type A aortic dissection. Residual aortic regurgitation (AR) was evaluated, grading 0 to Ⅳ+ by echocardiography. The survival and root reoperation-free rates were also assessed. The operative mortality was 9.5% (6 patients). Early postoperative AR ≦Ⅰ+, =Ⅱ+ and ≧Ⅲ+ were 93, 7 and 0%, respectively. Late postoperative AR≧Ⅲ+ was observed in 4 patients. Root reoperation was performed in 4 patients (7.0%). In a case of reoperation, medial degeneration was found in the aortic wall, suggesting toxic effect of GRF glue. The actuarial survival and root reoperation-free rates at 9 years were 73 and 80% , respectively. In conclusion, aortic root preservation with the proper use of GRF glue has long-term durability with very low adverse effect.

Total aortic arch replacement using the‘elephant trunk (ET)’procedure has commonly been applied to acute aortic dissection, but enlargement of a residual false lumen of the descending thoracic aorta sometimes occurs. We performed endovascular stent-grafting to close the entry as the second operation and obtained successful outcomes. From April 1997 to January 2004, we performed the modified ET procedure for acute aortic dissection in 29 patients and evaluated postoperative changes of the false lumen. In many cases of the residual false lumen, kinks and wrinkles were observed at the site of the ET grafts in the descending aorta. An adequate length of ET would be about 8 cm long to prevent kinking, and a diameter about 20 mm to prevent wrinkles.