5cm未満の腹部大動脈瘤を経過観察することは妥当か? [in Japanese] Is It Valid to Follow up Abdominal Aortic Aneurysms Smaller Than 5cm in Diameter? [in Japanese]
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われわれは最大短径が5cm以上の腹部大動脈瘤 (AAA) に対しては積極的に手術を行い, 5cm未満の症例は経過観察し, 5cm以上に増大した時点で手術を行う方針としている. この妥当性を検証するため, 全受診例の遠隔予後を調査検討した. 8年間に受診した最大短径4cm以上の非破裂AAA全症例を対象とし, 各症例の瘤径, 治療方針, 非手術例では遠隔期手術, 破裂発生, 転帰を調査し, 早期に手術施行した早期手術群, 手術非施行の経過観察群 (5cm未満 : 4cm観察群, 5cm以上 : 5cm観察群) に分け検討した. 全AAA 261例中1例が追跡不能で検討症例は260例, 追跡率99.6%であった (早期手術群125例, 経過観察群135例). 経過観察群中52例に遠隔期に待機手術が施行された (全例5cm以上). 経過観察群の14例で破裂が発生したが, 5cm未満での破裂はなかった. 5cm観察群の破裂の累積発生率は4cm観察群に比べ有意に高かった. 経過観察群の初診後累積生存率は早期手術群に比べ有意に予後が悪かった (5年生存率 : 早期手術群77.8%, 経過観察群58.3%) が, 4cm観察群は早期手術群や日本人の推定予後曲線と同様であった. 待機手術例の在院死亡率は0.6%で, 術後累積生存率は早期手術群と経過観察の後手術を行った群とに差はなかった (早期手術群76.8%, 経過観察群75.1%). また4cm観察群と5cm観察群とでも術後予後に相違はなかった (4cm観察群74.8%, 5cm観察群78.6%). 今回の検討の結果から, 5cm未満の腹部大動脈瘤は注意深い経過観察を行い, 瘤が5cm以上に増大した時点で待機手術を施行するのが妥当と考える.
<b>Background:</b> We have performed elective surgery for abdominal aortic aneurysm (AAA) in accordance with our policy that 5 cm is the best threshold for repair of AAA. We conducted a retrospective study to determine whether our policy is valid in all our patients with AAA. <b>Methods:</b> All 260 patients who presented at Tohoku University Hospital with AAAs ≥4 cm between 1996 and 2003 were reviewed. We examined the size of the aneurysm at the first presentation, operation for AAA, length of survival and cause of death. We divided patients into two groups. One was the patients who received early surgery and the other is those who were observed and follow up. The latter group was further divided in two subgroups: the 4 cm-observation group in which the size of the aneurysm was smaller than 5 cm in diameter and the 5 cm-observation group in which the size of aneurysm was larger than 5 cm at first presentation. We investigated the outcome and compared the groups. <b>Results:</b> Among these patients, 125 patients (48.1%) underwent early elective operation (early surgery group) and 135 patients (51.9%) were not offered operative treatment (4 cm-observation group: 92,5 cm-observation group: 43). Almost all patients in the early surgery group had an AAA of 5 cm or greater. In 52 cases in the observation group, additional elective surgery was performed during the follow-up period, and all of those 52 patients had an AAA of 5 cm or greater. Rupture of the aneurysm occurred in 14 cases in the observation group and all ruptured aneurysms had reached 5 cm. No rupture occurred in aneurysms smaller than 5 cm in diameter. The cumulative incidence of probable rupture was significantly higher in the 5 cm-observation group than in the 4 cm-observaton group (p<0.0001). The cumulative 5-year survival rate of the early surgery group (77.8%) was significantly higher than that of the observation group (58.3%). However, the outcome in the 4 cm-observation group was almost same as in the early surgery group and the estimated prognosis curve of the Japanese normal population based on Life Table for Japan; therefore the outcome was significantly poorer in the 5 cm-observation group. The operative mortality rate was 0.6% in the patients who received elective surgery and there was no statistical significance in the cumulative survival rate after operation between the early surgery group and the additional elective surgery after observation (76.8% and 75.1% in 5-year survival rate, prospectively). There was also no statistical significance in the outcome after operation between the 4 cm-observation group and the 5 cm-observation group (74.8% and 78.6% in 5-year survival rate, prospectively). <b>Conclusion:</b> From our present study, it is valid that AAA smaller than 5 cm in diameter should be observed and followed up.
- Jpn. J. Vasc. Surg.
Jpn. J. Vasc. Surg. 15(1), 3-9, 2006-02-25
JAPANESE SOCIETY FOR VASCULAR SURGERY