Growth Rate of Affected Aorta in Patients With Type B Partially Closed Aortic Dissection

Background. Our purpose was to evaluate the growth rate (GR) of the affected aorta and to clarify whether a partially closed false lumen can affect aortic enlargement in patients with type B double-barrelled aortic dissection (AD). Methods. Seventy-one patients (mean age, 64.4 years) who had experienced AD were enrolled in this study. Regular follow-up computed tomography studies (mean, 48.9 months) were performed. During the follow-up period, aortic diameter was measured with computed tomography. The fastest GR was calculated. Results. Based on final computed tomography findings, the patients were divided into three groups: those with completely closed false lumens (n = 8), those with partially closed false lumens (n = 20), and those with patent false lumens (n = 43). Among the patients with partially closed false lumens, 3 of 20 (15%) had a sac formation type and (85%) had a non-sac formation type. The mean fastest GRs for groups with a completely closed false lumen, partially closed false lumen, and patent false lumen were -0.2 +/- 0.6, 4.0 +/- 4.3, and 4.9 +/- 4.5 mm/year, respectively. The differences among the three groups were statistically significant (p = 0.0149). In the partially closed false lumen group, the mean fastest GRs of the sac and non-sac formation types were 12.7 +/- 1.1 and 2.6 +/- 2.7 mm/year, respectively; this difference is statistically significant (p = 0.007). Conclusions. Affected aortas with partially closed false lumens do not exhibit the highest GR. The status of a partially closed false lumen is not a significant risk factor for enlargement; however, careful follow-up study is needed whenever the sac formation type of partially closed false lumen is identified. (Ann Thorac Surg 2009; 88: 1251-7) (C) 2009 by The Society of Thoracic Surgeons