Determination of Entry Site for Acute Type A Aortic Dissection by Initial Enhanced CT-Scan.
10.4326/jjcvs.31.12
- VernacularTitle:急性Ａ型大動脈解離症例の術前造影ＣＴ検査からみたｅｎｔｒｙ局在部位の検討
- Author:
Takenori Mase
;
Chihiro Narumiya
;
Takahiko Aoyama
;
Yoshihisa Nagata
- Publication Type:Journal Article
- From:Japanese Journal of Cardiovascular Surgery
2002;31(1):12-17
- CountryJapan
- Language:Japanese
-
Abstract:
Acute type A aortic dissection presents a surgical emergency because conservative therapy is not effective in the majority of instances. Enhanced CT-scan of the chest is commonly available and is considered to be an optimal diagnostic method for this disease. The operative strategy is to resect the primary tear to close the entry site of the aortic dissection and replace it with a tubular Dacron graft. Therefore, the existence of the entry site is important in determining the operative procedure. Based on the numerical value of the enhanced CT-scan inspection, the present study seeks to preoperatively identify the location of the presumed entry site in aortic dissection. From May 1996 to June 1999, 21 consecutive patients (Marfan's syndrome excluded) with acute type A aortic dissection underwent surgical treatment. Nineteen patients were preoperatively examined by enhanced CT-scan: 11 men and 8 women, with a mean age of 61 years. CT-scan slices used for early diagnosis were of the ascending aorta, aortic arch, descending aorta, and thoracoabdominal aorta. The largest diameters of the whole and true lumen were measured from cross-sectional aortic images with a personal computer, and the areas of the whole and true lumen were obtained by the manual tracing method. The true ratio was calculated for the largest diameter and area of the whole lumen. The nineteen patients were divided into two groups according to the location of the entry site based on the operating views. Seven patients with the entry site in the ascending aorta were classified as group A, and twelve patients with the entry site further in the aortic arch and descending aorta were classified as group B. Comparisons were performed by non-parametric analysis. Moreover, a discriminant analysis was applied to evaluate the classification between the two groups. The ratio of the largest diameter of the true lumen in group A at the level of the ascending and descending aorta was significantly greater than that in group B (75.0±11.3 vs. 59.7±14.0%, 82.7±8.6 vs. 70.1±11.4%). Linear discriminant analysis resulted in the correct classification rate of 68.2%, and 77.3%, respectively. The ratio of the area of the true lumen in group A at the level of the aortic arch was also significantly greater than in group B (65.4±17.3 vs. 45.7±15.8%) and linear discriminant analysis resulted in the correct classification rate of 55.1%, When the entry site was located in the aortic arch, the diameter of the true lumen was seen to be smaller in the ascending and descending aorta, and the dissecting lumen appeared enlarged. When the entry site is located in the ascending aorta, the ratio of the area of the true lumen in the aortic arch was significantly higher (55.1%). Detailed examination of enhanced CT-scans is useful to determine the location of the entry site and the treatment strategy for this disease.
