The effect of myocardial preservation technique on supraventricular tachycardia following aortic valve replacement

We studied 100 patients who underwent an isolated aortic valve replacement (AVR) between 1974 and 1991. The patients were divided into the following two groups and compared: group A, which consisted of 40 patients operated on before 1978 who underwent continuous left coronary perfusion with blood; and group B, which consisted of 60 patients operated on after 1979 in whom St. Thomas solution was used in combination with topical cardiac cooling. Moreover, we divided the group B patients into two subgroups: group Bl, who underwent AVR before 1986 during which we administered St. Thomas solution with ice slush every 30 min; and group B2, who had AVR after 1986 in which we used St. Thomas solution with a cold saline (4°C) solution and treated with a small amount of slushed ice every 15 min. The incidence of supraventricular tachycardias was 15% in group A, 50% in group BI, and 15% in group B2. The severity of preoperative New York Heart Association (NYHA) functional class, the type of valve lesions, cardiothoracic ratio, left ventricular function, aortic clamp time, bypass time, and use of drugs did not correlate with the incidence of supraventricular tachycardias in either group A or B. In group B2 patients, we paid a lot of attention to cooling the right atrium as well as the left ventricle by immersing the whole heart using a 4°C saline solution, which led to a remarkable reduction of the incidence of supraventricular tachycardia. This fact indicates that right atrial preservation is one of the most important factors for reducing the incidence of supraventricular tachycardia.     

再次液氮冷冻保存对猪主动脉瓣膜细胞活性及组织结构的影响

目的了解再次冷冻保存对主动脉瓣膜细胞活性及组织结构的影响,探讨液氮冷冻保存的主动脉瓣解冻后再次冷冻保存使用的可行性.方法将猪主动脉瓣叶在抗菌处理后按随机数字表法分成三组,每组6个瓣叶,组Ⅰ作对照,组Ⅱ、组Ⅲ控制降温速率降至-80℃后在液氮中保存,1个月后融化解冻.组Ⅲ解冻并在室温下放置15分钟后更换保存液,再次降温至-80℃后放入液氮中保存,2个月后再融化解冻.采用XTT比色法测定各组瓣膜细胞活性,用免疫荧光组织化学染色、光学显微镜、透射电子显微镜行组织学检测.结果组Ⅱ冷冻保存后瓣膜细胞活性下降到组Ⅰ的63.97%,组织结构一定程度受损;组Ⅲ瓣膜细胞活性下降至组Ⅰ的38.60%,组织结构损害也进一步加重.结论液氮冷冻保存的猪主动脉瓣一经解冻融化,不宜再次冷冻保存使用.     

Acute type a aortic dissection complicated with acute inferior myocardial infarction following aortic valve replacement

Acute aortic dissection complicated with acute myocardial infarction (AMI) is the most fatal situation. We experienced the successful treatment for acute type A aortic dissection complicated with inferior AMI following aortic valve replacement (AVR). A 60-year-old man had had AVR for aortic regurgitation. Sixteen months after the AVR, he had a sudden onset of severe chest pain with complete atrioventricular block. Immediately, temporary pacing and cardiac catheterization were conducted, showing the occlusion of the right coronary artery due to acute type A aortic dissection. On his way to our hospital, direct current shock was conducted 3 times for ventricular fibrillation. We replaced the ascending aorta combined with coronary artery bypass grafting and the postoperative course was uneventful. The key to treat acute aortic dissection complicated with AMI is early accurate diagnosis, prompt temporary pacing for bradycardia, defibrillation for lethal arrhythmia and insertion of a perfusion catheter if possible. These preoperative hemodynamic stabilization gives us the chance to save these patients.     

腔内修复术治疗胸腹主动脉瘤经验总结(附6例报告)

目的总结腔内修复术治疗胸腹主动脉瘤的经验。方法回顾性分析2004年12月-2006年5月6例降主动脉瘤及夹层动脉瘤患者施行腔内修复术的病例资料。结果真性动脉瘤2例,假性动脉瘤1例,夹层动脉瘤3例,共植入支架8枚。术后内瘘大出血死亡1例,腹股沟血肿1例,其余患者均于术后2 d下床活动。未发生肺部感染、肺不张、截瘫、腹胀、肾衰、脑梗塞、心功能不全、心律失常等并发症。术后1周复查CT,支架无扭曲移位,封堵效果满意。结论腔内修复术的近期治疗效果确切,创伤小,并发症少,其远期效果还有待进一步观察。短瘤颈者,DeBakeyⅠ、Ⅱ型夹层动脉瘤患者,累及重要血管的主动脉瘤患者如何进行腔内修复术还有待进一步研究。     

Alteration of Elastin, Collagen and their Cross-links in Abdominal Aortic Aneurysms

OBJECTIVES: although the mechanism of arterial dilation and aneurysm development has not been clarified, the degradation of elastin and collagen plays undoubtedly a critical role. We evaluated the elastin and collagen content through the detection of their cross-links in aneurysmal and non-aneurysmal abdominal aortic walls. MATERIALS AND METHODS: in 26 human abdominal aortic aneurysm specimens obtained during surgery and in 24 autopsy control samples of non-aneurysmal abdominal aorta the tissue content of elastin and collagen cross-links were measured by HPLC. Collagen was also detected by evaluating two characteristic amino acids, 4-hydroxyproline (4-hypro) with a colorimetric method and 5-hydroxylysine (5-hylys) by gas chromatography. RESULTS: significantly fewer elastin cross-links were found in aneurysm samples compared to controls (desmosines and isodesmosines: 90% reduction; p<0.01). The opposite was true for pyridinoline collagen cross-links (350% increase) and deoxypyridinolines (100% increase, p=0.01). Tissue content of 5-hylys, 4-hypro and total amino acids were reduced significantly by 50% in aneurysmal samples. CONCLUSIONS: beside confirming decreased elastin content in aneurysmal walls, these results show a concurrent increase of collagen cross-links. Since total collagen markers were decreased (decreased 4-hypro and 5-hylys) it is reasonable to suggest that in aneurysmal aortic walls old collagen accumulates cross-links while new collagen biosynthesis is somehow defective.     

Aortic regurgitation secondary to diastolic prolapse of a tubular intimal flap into the left ventricle in a patient with anuloaortic ectasia

A 32-year-old man with distal skeletal manifestations of Marfan's syndrome had experienced shortness of breath and orthopnea for one month. Physical examination showed the presence of severe aortic regurgitation. Both noninvasive and invasive studies revealed that the aortic regurgitation was induced by previously undescribed peculiar and unusual etiology: diastolic prolapse of a circumferentially dissected tubular intimal flap into the left ventricle. The patient underwent surgical repair with striking clinical improvement.     

Advantages of using the midline incision right retroperitoneal approach for abdominal aortic aneurysm repair

This study was conducted to compare the midline incision right retroperitoneal approach for repairing abdominal aortic aneurysms (AAA) with the transperitoneal approach. The intra- and postoperative course of 15 patients who underwent AAA repair using the transperitoneal approach between 1987 and 1991 and another 15 patients who underwent AAA repair using the retroperitoneal approach between 1991 and 1994 were evaluated. The incidence of postoperative wound complications was also assessed. There was no operative or hospital death in either group. Although a significantly longer interval was required from the incision to the aortic clamp using the extraperitoneal method, there were no statistical differences in the aortic clamping time, total operation time, or blood loss between the two groups. On the other hand, there was a statistically significant improvement in bowel function and a significant reduction in the length of postoperative hospitalization following the extraperitoneal procedure. Furthermore, no wound complications such as those associated with the left flank incision developed after the extraperitoneal procedure. Thus, we recommend the midline incision right retroperitoneal approach for AAA as it does not involve muscle division and is associated with fewer complications.     

3-D echocardiographic imaging of double aortic arch.

Delineation of arch abnormalities is difficult by conventional 2-D echocardiography and MRI has been the investigation of choice. 3-D echocardiography is increasingly used in congenital heart disease for both functional anatomy and morphology. This case report demonstrates that 3-D echocardiography can be used in delineating arch anomalies, which can avoid further imaging that needs a general anaesthetic.     

鸡胚第一对弓动脉的发生

用印地安墨汁注入活体鸡胚心脏，在体现显微镜下观察１１２例第１０～２０期鸡胚第一对弓动脉的发生。第一对弓动脉于第１０期出现，至第２０期退化消失。第一对弓动脉出现时尚无相应的第一咽弓，随着第一咽弓的出现，第一对弓动脉的起始端形成一个突入第一咽弓内的动脉瘤样隆起，此隆起随着第一咽弓的增大逐渐发育成一对贯穿第一咽弓的弓状血管。第一对弓动脉可以分为位于第一咽弓内的近侧段和位于此咽弓之外，与背主动脉相连的远侧段。     

Imaging of thoracic aortic dissection

Acute thoracic aortic dissection has a high mortality if untreated, so the diagnosis must be rapidly made if mortality is to be lowered significantly. Multiple imaging techniques are often used. This retrospective study from 1988 to 1993 assesses the usefulness in diagnosis of chest X-rays, computed tomography (CT) scanning, aortography, magnetic resonance imaging (MRI), trans-thoracic (TTE) and trans-oesophageal (TOE) echocardiography. Forty-two patients with a final clinical diagnosis of dissection were studied. The diagnosis was confirmed in 16 (13 at surgery and three at autopsy). Three died with dissection given as the only cause for death. Chest X-ray abnormalities were seen in all 19 patients with surgery or death from dissection, with a widened mediastinum and/or dilated aorta being present in 17. In the group of 16 patients with surgery or autopsy proof, CT scans found dissections in 9 of 12 patients studied and correctly classified the type in only five. Aortography was performed in five, with accurate depiction of dissection and type in all. TTE found dissections in three of eight patients imaged by this method. MRI and TOE were performed each on two patients, with accurate depiction of dissection and type in each. Because of the relatively low sensitivity of CT scanning in defining aortic dissections Westmead Hospital is currently assessing the use of TOE as the prime imaging modality prior to surgical intervention.