- Email: [email protected]
Evolution of aortic dissection after surgical repair
Evolution of Aortic Dissection After Surgical Repair Rossella Fattori, MD, Letizia Bacchi-Reggiani, MSc, Paola Bertaccini, MD, Gabriella Napoli, MD, Francesca Fusco, MD, Massimo Longo, MD, Angelo Pierangeli, MD, and Giampaolo Gavelli, MD Patients after aortic dissection repair still have long-term unfavorable prognosis and need careful monitoring. The purpose of this study was to analyze the evolution of aortic dissection after surgical repair in correlation to anatomic changes emerging from systematic magnetic resonance imaging (MRI) follow-up. Between January 1992 and June 1998, 70 patients underwent surgery for type A aortic dissection. Fifty-eight patients were discharged from the hospital (17% operative mortality) and were followed by serial MRI for 12 to 90 months after surgery. In all, 436 postoperative MRI examinations were analyzed. In 13 patients (22.5%) no residual intimal flap was identified, whereas 45 patients (77.5%) presented with distal dissection, with a partial thrombosis of the false lumen in 24. The yearly aortic growth rate
was maximum in the descending aortic segment (0.37 ⴞ 0.43 cm) and was significantly higher in the absence of thrombus in the false lumen (0.56 ⴞ 0.57 cm) (p <0.05). There were 4 sudden deaths, with documented aortic rupture in 2. Sixteen patients underwent reoperation for expanding aortic diameter. In all but 1 patient, a residual dissection was present (in 13 without any thrombosis of the false lumen). Close MRI follow-up in patients after dissection surgical repair can identify the progression of aortic pathology, providing effective prevention of aortic rupture and timely reoperation. Thrombosis of the false lumen appears to be a protective factor against aortic dilation. 䊚2000 by Excerpta Medica, Inc. (Am J Cardiol 2000;86:868 – 872)
dvances in diagnosis, surgical techniques, and perioperative management have significantly imA proved survival in patients after aortic dissection re-
patients fulfilled the diagnostic criteria for Marfan syndrome.10 The operative techniques used were the following: replacement of the ascending aorta with interposition graft (31 patients), replacement of the ascending aorta and aortic arch (4 patients), replacement of the ascending aorta and valve by composite graft (Bentall technique in 17 cases and Cabrol technique in 2 cases), and interposition graft and separate aortic valve replacement (4 patients). All survivors were followed in the outpatient clinic by serial magnetic resonance imaging (MRI). The institutional review board had approved the study and an informed consent was obtained. No patient was lost to followup. Thirty-nine patients were treated with -blocker therapy (in 25 associated with calcium antagonists or angiotensin-converting enzyme inhibitors), and 19 patients did not receive any antihypertensive treatment. All patients had control of systemic blood pressure during follow-up. The MRI of the thoracic and abdominal aorta was performed before discharge and at 6 months after surgery. In the absence of specific problems, the interval between subsequent MRI studies depended on diameter and progression of aortic dilation: the interval was 6 months for patients with aortic diameter ⱖ5 cm and/or progression of aortic dilation, and 12 months for patients in stable condition and with diameters ⬍5 cm. Follow-up ranged from 12 to 90 months after surgery. Imaging follow-up: Imaging of the thoracic and abdominal aorta was performed on a 0.5T MR unit (MR Max Plus GE Medical Systems, Milwaukee, Wisconsin). In all patients an electrocardiographicgated multislice spin-echo sequence of the entire thoracic aorta was acquired in transaxial, oblique sagittal,
pair, contributing to lower operative mortality (from 40% to 50% in the 1970s to 5% to 7% in recent series).1– 8 Nevertheless, long-term follow-up still fails to demonstrate substantial improvement in survival, despite the accepted concept of closer postoperative surveillance.9 It is recognized that dilation and subsequent rupture of the distal aorta is the most common cause of death after surgery for aortic dissection.2,8 However, considering the high surgical risk of reoperation, it is difficult to identify critical parameters for prophylactic surgical repair. Thus, the aim of this study was to analyze the evolution of aortic dissection after surgical repair in correlation to anatomic changes on follow-up imaging.
METHODS
Patients: Between January 1992 and June 1998, 70 patients underwent surgery for type A aortic dissection at the Department of Cardiac Surgery of the University Hospital of Bologna. Aortic dissection was acute in 61 patients (87.1%) and chronic in 9 (12.9%). Twelve patients died in the perioperative period (hospital mortality 17%) and 58 (83%) were discharged from the hospital. There were 45 men and 13 women, aged 22 to 73 years (mean 50.2 ⫾ 13.7). Thirteen From the Institute of Radiology and Cardiac Surgery, University of Bologna, Bologna, Italy. Manuscript received January 19, 2000; revised manuscript received and accepted April 21, 2000. Address for reprints: Rossella Fattori, MD, Radiologia 3°, University Hospital S. Orsola, Via Massarenti 9, 40138 Bologna Italy. E-mail: [email protected].
868
©2000 by Excerpta Medica, Inc. All rights reserved. The American Journal of Cardiology Vol. 86 October 15, 2000
0002-9149/00/$–see front matter PII S0002-9149(00)01108-5
with measurement at: (1) the ascending aorta at Valsalva sinuses, prosthetic conduit, distal anastomosis; (2) aortic arch at the level of the innominate artery and before the subclavian artery; (3) the descending aorta just beyond the subclavian artery, in the middle portion and at the diaphragmatic hiatus, and (4) the abdominal aorta in the proximal and in infrarenal portion. The maximal cross-sectional lumen diameter was measured as the distance between the inner wall and the opposite perpendicular inner wall for each segment. Growth rates were weighted for the different interval time between 2 controls, dividing the changes in dimensions by the days elapsed between studies and FIGURE 1. MRI axial (left) and sagittal (right) spin echo images of the thoracic aorta. Note false lumen thrombosis in the aortic arch (left). No intimal flap is then multiplying by 365. For this analyvisible. sis, all the interim scans between the first follow-up and last MRI control were used. The false lumen was considered patent by signal void on spin-echo images and homogenous high-signal intensity on gradient-echo images. The presence of material in the false lumen of constant signal intensity on both spin-echo and gradient-echo sequences was classified as thrombus. Data analysis: To assess the reproducibility of the measurements, intra- and interobserver variability was calculated. Six patients were considered and 3 different aortic segments selected. Two observers obtained all measurements independently on 5 separate occasions. To avoid learning effects that could result in low estimates of intraobserver error, a time interval of 1 day was inserted between 2 readings of an examination by the same observer. Intra- and interobserver variability is reported as variances, standard deviations, and confidence intervals for measurements. Aortic measures were evaluated by the t test, 1-way analysis of variance followed by Scheffe´’s test and repeated-measures analysis of variance. The incidence of postoperative events was analyzed by chi-square test. A p level ⬍0.05 was considered statistically significant.
RESULTS
FIGURE 2. MRI sagittal gradient echo image of the thoracic aorta. The intimal flap is visible in the descending aorta with partial thrombosis of the false lumen.
and coronal planes, with a repetition time dependent on the RR interval. Additionally, gradient-echo sequences (TE 17 ms, flip angle 35°, repetition time 25 ms) were performed in the oblique sagittal plane. The number of MRI examinations available for each patient ranged from 2 to 9, with a total number of 436 MRIs. In each patient the prosthetic aortic segment, distal and proximal anastomoses, and morphology and diameter of the thoracic and abdominal aorta along with supraortic or visceral vessels were evaluated,
Fate of residual dissection: Forty-five of the 58 patients (77.5%) presented with a residual dissection extending in the thoracic descending and abdominal aortae. The false lumen was found to be thrombosed in 13 cases (22.5%) with no residual intimal flap (Figure 1). Among patients with residual false lumen, a partial thrombosis was visualized in 24 (41.3%) (Figure 2), whereas they remained completely patent in 21 (36.2%). In all but 3 patients (with thrombosed false lumen), a progressive increase in the aortic dimension was observed (Figure 3). The descending aorta just below the left subclavian artery was the site of maximum increment in diameter (0.37 ⫾ 0.43 cm) (Table 1). The yearly growth rate was significantly greater in the presence of patent false lumen than in the case of thrombosed false lumen (0.56 ⫾ 0.57 vs
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FIGURE 3. Maximal diameters of thoracic descending aorta over time in 3 groups of patients: Triangles, no false lumen; circles, partial thrombosis of the false lumen; boxes, no thrombosis of the false lumen. Solid lines represent 90% confidence limits of all patients for each yearly control. Repeated-measures analysis of variance: F ⴝ 19.3, p <0.0001; false lumen thrombosis effect F ⴝ 59.7, p <0.0001; time interval effect F ⴝ 28.6, p <0.0001; Postop ⴝ MRI control before discharge.
0.11 ⫾ 0.17 cm, Scheffe´’s test p ⬍0.05) (Table 2). No significant difference in the rate of dilation was found between patients with and without Marfan syndrome. Similarly, the incremental diameter enlargement of the residual aorta was not influenced by -blocker therapy (Table 1). Intraobserver reproducibility was 3.0% for aortic arch, 2.5% for descending aorta, and 3.2% for abdominal aorta. Interobserver reproducibility was 3.2% for aortic arch, 1.9% for descending aorta, and 3.4% for abdominal aorta. Long-term follow-up: There were 6 late deaths (10.3%), between 10 months and 6 years after surgery. Four patients died suddenly. In all of them, MRI documented persistent false lumen (in 1 with partial thrombosis and in 3 without thrombosis [Table 3]). In 2 of them autopsy documented aortic rupture of the descending aorta. The diameter of the ruptured segment at previous MRI follow-up was 6.5 and 6 cm, respectively, and both patients had been scheduled for reoperation. During the 7-year period of follow-up, 16 patients (27.5%) underwent reoperation because of progressive dilation (⬎5.5 cm) of the untreated aortic segments (Table 3). All but 1 presented with a patent distal dissection (in 10 without any formation of thrombus in the false lumen). 870 THE AMERICAN JOURNAL OF CARDIOLOGY姞
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DISCUSSION Surgery of aortic dissection still remains a challenge in cardiovascular surgery. The goal of surgical treatment is the prevention of aortic rupture of the highest risk segment (i.e., the proximal portion of the ascending aorta). Early detection of acute aortic dissection by new high-resolution imaging modalities and the referral of patients for surgery before development of complications lead to reduction in early mortality over the years. Nevertheless, survivors after initial repair still remain at considerable risk of future complications. Increasing experience with repair of the ascending aorta had significantly reduced the occurrence of late reoperation related to failure of proximal repair. Extensive resection of all the proximal entry tears, increasing use of aortic root repair or replacement, biologic glue, and Teflon reinforcement may ensure optimal results in surgery of the ascending aorta. The poor prognosis of patients after aortic dissection repair is mainly related to the condition of the aorta distal from the site of repair. Recently, 2 large surgical series have examined their experience in surgical management of aortic dissection over a long period.11,12 The Stanford group emphasizes a significant reduction in operative mortality in 360 patients during 30 years: from 42% of operative mortality in OCTOBER 15, 2000
though it reduces the number of late reoperations, is associated with Thoracic higher operative mortality.14 ReNo. of Sinuses of Descending Abdominal cently, Ergin et al15 described the use Aortic Growth Patients Valsalva Aortic Arch Aorta Aorta of an intraluminal graft for the distal Total 58 0.12 ⫾ 0.18 0.10 ⫾ 0.18 0.37 ⫾ 0.43 0.15 ⫾ 0.30 anastomosis, to decrease the patency Acute 51 0.10 ⫾ 0.15 0.09 ⫾ 0.13 0.39 ⫾ 0.51 0.08 ⫾ 0.23 of distal false lumen after aortic disChronic 7 0.13 ⫾ 0.21 0.15 ⫾ 0.20 0.36 ⫾ 0.29 0.16 ⫾ 0.35 section repair. Interestingly, the acp Value 0.717 0.445 0.817 0.561 tuarial survival rate at 5 years for Marfan 13 0.40 ⫾ 0.19 0.06 ⫾ 0.09 0.48 ⫾ 0.29 0.21 ⫾ 0.22 No Marfan 45 0.11 ⫾ 0.17 0.11 ⫾ 0.20 0.33 ⫾ 0.45 0.14 ⫾ 0.32 patients with closed distal false lup Value 0.032 0.406 0.282 0.524 mens was 95% versus 76% in pa blockers 39 0.16 ⫾ 0.21 0.08 ⫾ 0.16 0.37 ⫾ 0.32 0.18 ⫾ 0.31 tients with open distal false lumens. No  blockers 19 0.04 ⫾ 0.07 0.14 ⫾ 0.24 0.35 ⫾ 0.62 0.07 ⫾ 0.09 Although the small number of pap Value 0.064 0.283 0.876 0.322 tients (n ⫽ 38) available for follow-up does not produce statistical significance, these data indicate that TABLE 2 Aortic Growth Rate (mean ⫾ SD cm/year) According to False Lumen the incidence of long-term events Evolution can be closely influenced by the conNo False False Lumen, False Lumen, dition of the false lumen, correAortic Segment Lumen Partial Thrombosis No Thrombosis p Value sponding to our findings. The increAortic arch 0.08 ⫾ 0.22 0.11 ⫾ 0.21 0.09 ⫾ 0.11 0.877 ment in diameter of the residual aorta Thoracic descending 0.11 ⫾ 0.17 0.34 ⫾ 0.32 0.56 ⫾ 0.57 0.010 was higher in patients with persistent aorta false lumen than in patients without Abdominal aorta 0.03 ⫾ 0.09 0.24 ⫾ 0.38 0.05 ⫾ 0.9 0.466 residual dissection. Interestingly, this observation does not apply to the aortic arch, but to the descending TABLE 3 Incidence of Late Postoperative Events thoracic aorta (0.56 vs 0.11 cm/year, Expanding Scheffe´’s test p ⬍0.05). Moreover No. of False Lumen the presence of partial thrombosis of Distal Dissection Patients (⬎5.5 cm) Reoperation Death the false lumen appears to be protecNo false lumen 13 1/13 (7.7%) 1 0 tive against dilation as suggested by False lumen, partial 24 7/24 (29.1%) 5 3 an aortic growth rate of 0.34 cm/year thrombosis in patients with partial thrombosis of False lumen, no 21 13/21 (61.9%) 10 3 the false lumen versus an increase of thrombosis 0.56 cm/year in patients without thrombus in the false lumen. Similarly, the number of late postoperaacute dissection during 1963 to 1972 to 26% during tive events, such as reoperation or sudden death, was 1988 to 1992 interval. Actuarial survival rates for significantly higher in patients with residual false luacute dissections at 5, 10, and 15 years were 55%, men and no thrombus. Conversely, the progression of 37%, and 24%, respectively. In the 20-year follow-up a distal dissection appeared to be independent of aortic of 527 patients reported by De Bakey and associates,9 elastic properties itself16,17: despite a trend in higher 57% survived at 5 years, 32% at 10 years, and only growth rate in the Marfan group, the yearly aortic 5% at 20 years; in the 205 late deaths, rupture of the increase was not statistically different when compared distal aorta was the most prevalent cause of death, with non-Marfan patients, and  blockers did not accounting for 29.3% of cases, and in the 23% of show any influence in the aortic growth rate (Table 1). cases the aortic diameter was ⬍6 cm. There is also a The low mortality rate (1 of 16) in patients who difference in occurrence of subsequent aneurysm for- underwent elective reoperation for expanding diamemation, accounting for 30% when the intimal flap was ter as well as a 10.3% 5-year overall mortality may be extended to the entire descending aorta, but only 14% considered an excellent result compared with the largwhen dissection is limited to the ascending aorta. est surgical series encouraging the effort in close A persistent distal false lumen has been reported in postoperative surveillance.18,19 75% to 100% of cases. The high frequency of a second A standard computer tomographic scan is still the entry tear in the aortic arch, in the descending aorta, or most common technique applied in the postoperative in both is responsible for patency of distal dissection evaluation of the thoracic aorta, but the use of radiaand for an unfavorable prognosis.13 Extensive resec- tion and contrast media and the possibility of partial tion of the proximal entry tear and the use volume errors due to its monoplane acquisition may of gelatin-resorcinol-formaldehyde glue represent be considered negative characteristics in serial imagadvances in surgical technique, improving results of ing follow-up.20 MRI can depict aortic wall features in the initial repair; however, it does not affect the fate of a multiplanar view, allowing a complete evaluation of distal dissection. Otherwise aggressive replacement of thoracic and abdominal aorta.21,22 With use of gradithe affected aortic segment including aortic arch, even ent-echo sequences, the thrombosis of the false lumen TABLE 1 Aortic Growth Rate (mean ⫾ SD cm/year) in Different Aortic Segments
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can easily be detected.23 Moreover, the high reproducibility of the parameters constitutes an essential characteristic in serial examinations in which a change in dimension may represent a prognostic finding in the difficult decision making of preventive surgical strategies. 1. Crawford SE. The diagnosis and management of aortic dissection. JAMA
1990;262:2537–2541. 2. Svensson LG, Crawford SE. Statistical analyses of operative results. In:
Cardiovascular and Vascular Disease of the Aorta. Philadelphia: WB Saunders, 1997:432– 455. 3. Kouchoukos NT, Dougenis D. Surgery of the thoracic aorta. N Engl J Med 1997;336 –26:1876 –1888. 4. Doroghazi RM, Slater EE, De Sanctis RW, Buckley MJ, Austen WG, Rosenthal S. Long-term survival of patients with treated aortic dissection. J Am Coll Cardiol 1984;3:1026 –1034. 5. Haverich A, Miller CD, Scott WC, Mitchell RS, Over PE, Stinson EB, Shumway NE. Acute and chronic aortic dissections— determinants of long-term outcome for operative survivors. Circulation 1985;72(suppl II):II-22–II-34. 6. Glower DD, Speier RH, White WD, Smith RL, Rankin JS, Wolfe WG. Management and long-term outcome of aortic dissection. Ann Surg 1991;214: 31– 41. 7. Rizzo RJ, Aranki SF, Aklog L, Couper GS, Adams DH, Collins JJ Jr, Kinchia NM, AllreEN, Cohn LH. Rapid noninvasive diagnosis and surgical repair of acute ascending aortic dissection: improved survival with less angiography. J Thorac Cardiovasc Surg 1994;108:567–575. 8. Heinemann M, Laas J, Karck M, Borst HG. Thoracic aortic aneurysms after acute type A aortic dissection: necessity for follow-up. Ann Thorac Surg 1990; 49:580 –584. 9. De Bakey ME, McCollum CH, Crawford ES, Morris GC Jr, Howell J, Noon GP, Lawrie G. Dissection and dissecting aneurysms of the aorta: 20-year follow-up of 527 patients treated surgically. Surgery 1982;92:1118 –1134. 10. De Paepe A, Devereux RB, Dietz HC, Henneken CM, Pyeritz RE. Revised diagnostic criteria for the Marfan syndrome. Am J Med Genet 1996;62:417– 426.
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11. Svensson LG, Crawford SE, Hess KR, Coselli JS, Safi HJ. Dissection of the
aorta and dissecting aortic aneurysms. Improving early and long-term surgical results. Circulation 1990;82(suppl IV):IV-24 –IV-38. 12. Fann JI, Smith JA, Miller CD, Mitchell S, Moore KA, Grunkemeier G, Stinson EB, Oyer PE, Reitz BA, Shumway NE. Surgical management of aortic dissection during a 30-year period. Circulation 1995;92(suppl II):II-110 –II-121. 13. Dinsmore RE, Willerson JT, Buckley MJ. Dissecting aneurysm of the aorta. Aortographic features affecting prognosis. Radiology 1972;105:567–572. 14. Crawford SE, Kirklin JW, Naftel DC, Svensson LG, Coselli JS, Safi HJ. Surgery for acute dissection of ascending aorta. Should the arch be included? J Thorac Cardiovasc Surg 1992;104:46 –59. 15. Ergin MA, Phillips RA, Galla JD, Lansman SL, Mendelson DS, Quintana CS, Griepp RB. Significance of distal false lumen after type A dissection repair. Ann Thorac Surg 1994;57:820 – 825. 16. Kawamoto S, Bluemke DA, Traill TA, Zerhouni EA. Thoracoabdominal aorta in Marfan syndrome: MR imaging findings of progression of vasculopathy after surgical repair. Radiology 1997;203:727–732. 17. Leach SD, Toole AL, Stern H, De Natale RW, Tilson D. Effect of -adrenergic blockade on the growth-rate of abdominal aortic aneurysms. Arch Surg 1988;123:606 – 609. 18. Schor JS, Yerlioglu E, Galla JD, Lansman SL, Ergin MA, Griepp RB. Selective management of acute type B aortic dissection: long-term follow-up. Ann Thorac Surg 1996;61:1339 –1341. 19. Coady MA, Rizzo JA, Hammond GL, Mandapati D, Darr U, Kopf GS, Elefteriades JA. What is the appropriate size criterion for resection of thoracic aortic aneurysms? J Thorac Cardiovasc Surg 1997;113:476 – 491. 20. Hirose Y, Hamada S, Takamiya M, Imakita S, Naito H, Nishimura T. Aortic aneurysm: growth rates measured with CT. Radiology 1992;185:249 –252. 21. Fattori R, Descovich B, Bertaccini P, Celletti F, Caldarera I, Pierangeli A, Gavelli G. MRI evaluation of composite graft replacement of the ascending aorta: leakage detection by gd-DTPA enhancement. Radiology 1999;212:573– 577. 22. Pucillo AL, Schechter AG, Moggio RA, Kay RH, Tenner MS, Herman MV. Postoperative evaluation of ascending aorta prosthetic conduits by magnetic resonance imaging. Chest 1990;97:106 –116. 23. Sakuma H, Bourne MW, O’Sullivan M, Merrick SH, Ullyot DJ, Chatterjee K, Shimakawa A, Foo TK, Higgins CB. Evaluation of thoracic aortic dissection using breath-holding cine MRI. J Comput Assist Tomogr 1996;20:45–50.
OCTOBER 15, 2000
was maximum in the descending aortic segment (0.37 ⴞ 0.43 cm) and was significantly higher in the absence of thrombus in the false lumen (0.56 ⴞ 0.57 cm) (p <0.05). There were 4 sudden deaths, with documented aortic rupture in 2. Sixteen patients underwent reoperation for expanding aortic diameter. In all but 1 patient, a residual dissection was present (in 13 without any thrombosis of the false lumen). Close MRI follow-up in patients after dissection surgical repair can identify the progression of aortic pathology, providing effective prevention of aortic rupture and timely reoperation. Thrombosis of the false lumen appears to be a protective factor against aortic dilation. 䊚2000 by Excerpta Medica, Inc. (Am J Cardiol 2000;86:868 – 872)
dvances in diagnosis, surgical techniques, and perioperative management have significantly imA proved survival in patients after aortic dissection re-
patients fulfilled the diagnostic criteria for Marfan syndrome.10 The operative techniques used were the following: replacement of the ascending aorta with interposition graft (31 patients), replacement of the ascending aorta and aortic arch (4 patients), replacement of the ascending aorta and valve by composite graft (Bentall technique in 17 cases and Cabrol technique in 2 cases), and interposition graft and separate aortic valve replacement (4 patients). All survivors were followed in the outpatient clinic by serial magnetic resonance imaging (MRI). The institutional review board had approved the study and an informed consent was obtained. No patient was lost to followup. Thirty-nine patients were treated with -blocker therapy (in 25 associated with calcium antagonists or angiotensin-converting enzyme inhibitors), and 19 patients did not receive any antihypertensive treatment. All patients had control of systemic blood pressure during follow-up. The MRI of the thoracic and abdominal aorta was performed before discharge and at 6 months after surgery. In the absence of specific problems, the interval between subsequent MRI studies depended on diameter and progression of aortic dilation: the interval was 6 months for patients with aortic diameter ⱖ5 cm and/or progression of aortic dilation, and 12 months for patients in stable condition and with diameters ⬍5 cm. Follow-up ranged from 12 to 90 months after surgery. Imaging follow-up: Imaging of the thoracic and abdominal aorta was performed on a 0.5T MR unit (MR Max Plus GE Medical Systems, Milwaukee, Wisconsin). In all patients an electrocardiographicgated multislice spin-echo sequence of the entire thoracic aorta was acquired in transaxial, oblique sagittal,
pair, contributing to lower operative mortality (from 40% to 50% in the 1970s to 5% to 7% in recent series).1– 8 Nevertheless, long-term follow-up still fails to demonstrate substantial improvement in survival, despite the accepted concept of closer postoperative surveillance.9 It is recognized that dilation and subsequent rupture of the distal aorta is the most common cause of death after surgery for aortic dissection.2,8 However, considering the high surgical risk of reoperation, it is difficult to identify critical parameters for prophylactic surgical repair. Thus, the aim of this study was to analyze the evolution of aortic dissection after surgical repair in correlation to anatomic changes on follow-up imaging.
METHODS
Patients: Between January 1992 and June 1998, 70 patients underwent surgery for type A aortic dissection at the Department of Cardiac Surgery of the University Hospital of Bologna. Aortic dissection was acute in 61 patients (87.1%) and chronic in 9 (12.9%). Twelve patients died in the perioperative period (hospital mortality 17%) and 58 (83%) were discharged from the hospital. There were 45 men and 13 women, aged 22 to 73 years (mean 50.2 ⫾ 13.7). Thirteen From the Institute of Radiology and Cardiac Surgery, University of Bologna, Bologna, Italy. Manuscript received January 19, 2000; revised manuscript received and accepted April 21, 2000. Address for reprints: Rossella Fattori, MD, Radiologia 3°, University Hospital S. Orsola, Via Massarenti 9, 40138 Bologna Italy. E-mail: [email protected].
868
©2000 by Excerpta Medica, Inc. All rights reserved. The American Journal of Cardiology Vol. 86 October 15, 2000
0002-9149/00/$–see front matter PII S0002-9149(00)01108-5
with measurement at: (1) the ascending aorta at Valsalva sinuses, prosthetic conduit, distal anastomosis; (2) aortic arch at the level of the innominate artery and before the subclavian artery; (3) the descending aorta just beyond the subclavian artery, in the middle portion and at the diaphragmatic hiatus, and (4) the abdominal aorta in the proximal and in infrarenal portion. The maximal cross-sectional lumen diameter was measured as the distance between the inner wall and the opposite perpendicular inner wall for each segment. Growth rates were weighted for the different interval time between 2 controls, dividing the changes in dimensions by the days elapsed between studies and FIGURE 1. MRI axial (left) and sagittal (right) spin echo images of the thoracic aorta. Note false lumen thrombosis in the aortic arch (left). No intimal flap is then multiplying by 365. For this analyvisible. sis, all the interim scans between the first follow-up and last MRI control were used. The false lumen was considered patent by signal void on spin-echo images and homogenous high-signal intensity on gradient-echo images. The presence of material in the false lumen of constant signal intensity on both spin-echo and gradient-echo sequences was classified as thrombus. Data analysis: To assess the reproducibility of the measurements, intra- and interobserver variability was calculated. Six patients were considered and 3 different aortic segments selected. Two observers obtained all measurements independently on 5 separate occasions. To avoid learning effects that could result in low estimates of intraobserver error, a time interval of 1 day was inserted between 2 readings of an examination by the same observer. Intra- and interobserver variability is reported as variances, standard deviations, and confidence intervals for measurements. Aortic measures were evaluated by the t test, 1-way analysis of variance followed by Scheffe´’s test and repeated-measures analysis of variance. The incidence of postoperative events was analyzed by chi-square test. A p level ⬍0.05 was considered statistically significant.
RESULTS
FIGURE 2. MRI sagittal gradient echo image of the thoracic aorta. The intimal flap is visible in the descending aorta with partial thrombosis of the false lumen.
and coronal planes, with a repetition time dependent on the RR interval. Additionally, gradient-echo sequences (TE 17 ms, flip angle 35°, repetition time 25 ms) were performed in the oblique sagittal plane. The number of MRI examinations available for each patient ranged from 2 to 9, with a total number of 436 MRIs. In each patient the prosthetic aortic segment, distal and proximal anastomoses, and morphology and diameter of the thoracic and abdominal aorta along with supraortic or visceral vessels were evaluated,
Fate of residual dissection: Forty-five of the 58 patients (77.5%) presented with a residual dissection extending in the thoracic descending and abdominal aortae. The false lumen was found to be thrombosed in 13 cases (22.5%) with no residual intimal flap (Figure 1). Among patients with residual false lumen, a partial thrombosis was visualized in 24 (41.3%) (Figure 2), whereas they remained completely patent in 21 (36.2%). In all but 3 patients (with thrombosed false lumen), a progressive increase in the aortic dimension was observed (Figure 3). The descending aorta just below the left subclavian artery was the site of maximum increment in diameter (0.37 ⫾ 0.43 cm) (Table 1). The yearly growth rate was significantly greater in the presence of patent false lumen than in the case of thrombosed false lumen (0.56 ⫾ 0.57 vs
MISCELLANEOUS/AORTIC DISSECTION AFTER SURGICAL REPAIR
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FIGURE 3. Maximal diameters of thoracic descending aorta over time in 3 groups of patients: Triangles, no false lumen; circles, partial thrombosis of the false lumen; boxes, no thrombosis of the false lumen. Solid lines represent 90% confidence limits of all patients for each yearly control. Repeated-measures analysis of variance: F ⴝ 19.3, p <0.0001; false lumen thrombosis effect F ⴝ 59.7, p <0.0001; time interval effect F ⴝ 28.6, p <0.0001; Postop ⴝ MRI control before discharge.
0.11 ⫾ 0.17 cm, Scheffe´’s test p ⬍0.05) (Table 2). No significant difference in the rate of dilation was found between patients with and without Marfan syndrome. Similarly, the incremental diameter enlargement of the residual aorta was not influenced by -blocker therapy (Table 1). Intraobserver reproducibility was 3.0% for aortic arch, 2.5% for descending aorta, and 3.2% for abdominal aorta. Interobserver reproducibility was 3.2% for aortic arch, 1.9% for descending aorta, and 3.4% for abdominal aorta. Long-term follow-up: There were 6 late deaths (10.3%), between 10 months and 6 years after surgery. Four patients died suddenly. In all of them, MRI documented persistent false lumen (in 1 with partial thrombosis and in 3 without thrombosis [Table 3]). In 2 of them autopsy documented aortic rupture of the descending aorta. The diameter of the ruptured segment at previous MRI follow-up was 6.5 and 6 cm, respectively, and both patients had been scheduled for reoperation. During the 7-year period of follow-up, 16 patients (27.5%) underwent reoperation because of progressive dilation (⬎5.5 cm) of the untreated aortic segments (Table 3). All but 1 presented with a patent distal dissection (in 10 without any formation of thrombus in the false lumen). 870 THE AMERICAN JOURNAL OF CARDIOLOGY姞
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DISCUSSION Surgery of aortic dissection still remains a challenge in cardiovascular surgery. The goal of surgical treatment is the prevention of aortic rupture of the highest risk segment (i.e., the proximal portion of the ascending aorta). Early detection of acute aortic dissection by new high-resolution imaging modalities and the referral of patients for surgery before development of complications lead to reduction in early mortality over the years. Nevertheless, survivors after initial repair still remain at considerable risk of future complications. Increasing experience with repair of the ascending aorta had significantly reduced the occurrence of late reoperation related to failure of proximal repair. Extensive resection of all the proximal entry tears, increasing use of aortic root repair or replacement, biologic glue, and Teflon reinforcement may ensure optimal results in surgery of the ascending aorta. The poor prognosis of patients after aortic dissection repair is mainly related to the condition of the aorta distal from the site of repair. Recently, 2 large surgical series have examined their experience in surgical management of aortic dissection over a long period.11,12 The Stanford group emphasizes a significant reduction in operative mortality in 360 patients during 30 years: from 42% of operative mortality in OCTOBER 15, 2000
though it reduces the number of late reoperations, is associated with Thoracic higher operative mortality.14 ReNo. of Sinuses of Descending Abdominal cently, Ergin et al15 described the use Aortic Growth Patients Valsalva Aortic Arch Aorta Aorta of an intraluminal graft for the distal Total 58 0.12 ⫾ 0.18 0.10 ⫾ 0.18 0.37 ⫾ 0.43 0.15 ⫾ 0.30 anastomosis, to decrease the patency Acute 51 0.10 ⫾ 0.15 0.09 ⫾ 0.13 0.39 ⫾ 0.51 0.08 ⫾ 0.23 of distal false lumen after aortic disChronic 7 0.13 ⫾ 0.21 0.15 ⫾ 0.20 0.36 ⫾ 0.29 0.16 ⫾ 0.35 section repair. Interestingly, the acp Value 0.717 0.445 0.817 0.561 tuarial survival rate at 5 years for Marfan 13 0.40 ⫾ 0.19 0.06 ⫾ 0.09 0.48 ⫾ 0.29 0.21 ⫾ 0.22 No Marfan 45 0.11 ⫾ 0.17 0.11 ⫾ 0.20 0.33 ⫾ 0.45 0.14 ⫾ 0.32 patients with closed distal false lup Value 0.032 0.406 0.282 0.524 mens was 95% versus 76% in pa blockers 39 0.16 ⫾ 0.21 0.08 ⫾ 0.16 0.37 ⫾ 0.32 0.18 ⫾ 0.31 tients with open distal false lumens. No  blockers 19 0.04 ⫾ 0.07 0.14 ⫾ 0.24 0.35 ⫾ 0.62 0.07 ⫾ 0.09 Although the small number of pap Value 0.064 0.283 0.876 0.322 tients (n ⫽ 38) available for follow-up does not produce statistical significance, these data indicate that TABLE 2 Aortic Growth Rate (mean ⫾ SD cm/year) According to False Lumen the incidence of long-term events Evolution can be closely influenced by the conNo False False Lumen, False Lumen, dition of the false lumen, correAortic Segment Lumen Partial Thrombosis No Thrombosis p Value sponding to our findings. The increAortic arch 0.08 ⫾ 0.22 0.11 ⫾ 0.21 0.09 ⫾ 0.11 0.877 ment in diameter of the residual aorta Thoracic descending 0.11 ⫾ 0.17 0.34 ⫾ 0.32 0.56 ⫾ 0.57 0.010 was higher in patients with persistent aorta false lumen than in patients without Abdominal aorta 0.03 ⫾ 0.09 0.24 ⫾ 0.38 0.05 ⫾ 0.9 0.466 residual dissection. Interestingly, this observation does not apply to the aortic arch, but to the descending TABLE 3 Incidence of Late Postoperative Events thoracic aorta (0.56 vs 0.11 cm/year, Expanding Scheffe´’s test p ⬍0.05). Moreover No. of False Lumen the presence of partial thrombosis of Distal Dissection Patients (⬎5.5 cm) Reoperation Death the false lumen appears to be protecNo false lumen 13 1/13 (7.7%) 1 0 tive against dilation as suggested by False lumen, partial 24 7/24 (29.1%) 5 3 an aortic growth rate of 0.34 cm/year thrombosis in patients with partial thrombosis of False lumen, no 21 13/21 (61.9%) 10 3 the false lumen versus an increase of thrombosis 0.56 cm/year in patients without thrombus in the false lumen. Similarly, the number of late postoperaacute dissection during 1963 to 1972 to 26% during tive events, such as reoperation or sudden death, was 1988 to 1992 interval. Actuarial survival rates for significantly higher in patients with residual false luacute dissections at 5, 10, and 15 years were 55%, men and no thrombus. Conversely, the progression of 37%, and 24%, respectively. In the 20-year follow-up a distal dissection appeared to be independent of aortic of 527 patients reported by De Bakey and associates,9 elastic properties itself16,17: despite a trend in higher 57% survived at 5 years, 32% at 10 years, and only growth rate in the Marfan group, the yearly aortic 5% at 20 years; in the 205 late deaths, rupture of the increase was not statistically different when compared distal aorta was the most prevalent cause of death, with non-Marfan patients, and  blockers did not accounting for 29.3% of cases, and in the 23% of show any influence in the aortic growth rate (Table 1). cases the aortic diameter was ⬍6 cm. There is also a The low mortality rate (1 of 16) in patients who difference in occurrence of subsequent aneurysm for- underwent elective reoperation for expanding diamemation, accounting for 30% when the intimal flap was ter as well as a 10.3% 5-year overall mortality may be extended to the entire descending aorta, but only 14% considered an excellent result compared with the largwhen dissection is limited to the ascending aorta. est surgical series encouraging the effort in close A persistent distal false lumen has been reported in postoperative surveillance.18,19 75% to 100% of cases. The high frequency of a second A standard computer tomographic scan is still the entry tear in the aortic arch, in the descending aorta, or most common technique applied in the postoperative in both is responsible for patency of distal dissection evaluation of the thoracic aorta, but the use of radiaand for an unfavorable prognosis.13 Extensive resec- tion and contrast media and the possibility of partial tion of the proximal entry tear and the use volume errors due to its monoplane acquisition may of gelatin-resorcinol-formaldehyde glue represent be considered negative characteristics in serial imagadvances in surgical technique, improving results of ing follow-up.20 MRI can depict aortic wall features in the initial repair; however, it does not affect the fate of a multiplanar view, allowing a complete evaluation of distal dissection. Otherwise aggressive replacement of thoracic and abdominal aorta.21,22 With use of gradithe affected aortic segment including aortic arch, even ent-echo sequences, the thrombosis of the false lumen TABLE 1 Aortic Growth Rate (mean ⫾ SD cm/year) in Different Aortic Segments
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can easily be detected.23 Moreover, the high reproducibility of the parameters constitutes an essential characteristic in serial examinations in which a change in dimension may represent a prognostic finding in the difficult decision making of preventive surgical strategies. 1. Crawford SE. The diagnosis and management of aortic dissection. JAMA
1990;262:2537–2541. 2. Svensson LG, Crawford SE. Statistical analyses of operative results. In:
Cardiovascular and Vascular Disease of the Aorta. Philadelphia: WB Saunders, 1997:432– 455. 3. Kouchoukos NT, Dougenis D. Surgery of the thoracic aorta. N Engl J Med 1997;336 –26:1876 –1888. 4. Doroghazi RM, Slater EE, De Sanctis RW, Buckley MJ, Austen WG, Rosenthal S. Long-term survival of patients with treated aortic dissection. J Am Coll Cardiol 1984;3:1026 –1034. 5. Haverich A, Miller CD, Scott WC, Mitchell RS, Over PE, Stinson EB, Shumway NE. Acute and chronic aortic dissections— determinants of long-term outcome for operative survivors. Circulation 1985;72(suppl II):II-22–II-34. 6. Glower DD, Speier RH, White WD, Smith RL, Rankin JS, Wolfe WG. Management and long-term outcome of aortic dissection. Ann Surg 1991;214: 31– 41. 7. Rizzo RJ, Aranki SF, Aklog L, Couper GS, Adams DH, Collins JJ Jr, Kinchia NM, AllreEN, Cohn LH. Rapid noninvasive diagnosis and surgical repair of acute ascending aortic dissection: improved survival with less angiography. J Thorac Cardiovasc Surg 1994;108:567–575. 8. Heinemann M, Laas J, Karck M, Borst HG. Thoracic aortic aneurysms after acute type A aortic dissection: necessity for follow-up. Ann Thorac Surg 1990; 49:580 –584. 9. De Bakey ME, McCollum CH, Crawford ES, Morris GC Jr, Howell J, Noon GP, Lawrie G. Dissection and dissecting aneurysms of the aorta: 20-year follow-up of 527 patients treated surgically. Surgery 1982;92:1118 –1134. 10. De Paepe A, Devereux RB, Dietz HC, Henneken CM, Pyeritz RE. Revised diagnostic criteria for the Marfan syndrome. Am J Med Genet 1996;62:417– 426.
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11. Svensson LG, Crawford SE, Hess KR, Coselli JS, Safi HJ. Dissection of the
aorta and dissecting aortic aneurysms. Improving early and long-term surgical results. Circulation 1990;82(suppl IV):IV-24 –IV-38. 12. Fann JI, Smith JA, Miller CD, Mitchell S, Moore KA, Grunkemeier G, Stinson EB, Oyer PE, Reitz BA, Shumway NE. Surgical management of aortic dissection during a 30-year period. Circulation 1995;92(suppl II):II-110 –II-121. 13. Dinsmore RE, Willerson JT, Buckley MJ. Dissecting aneurysm of the aorta. Aortographic features affecting prognosis. Radiology 1972;105:567–572. 14. Crawford SE, Kirklin JW, Naftel DC, Svensson LG, Coselli JS, Safi HJ. Surgery for acute dissection of ascending aorta. Should the arch be included? J Thorac Cardiovasc Surg 1992;104:46 –59. 15. Ergin MA, Phillips RA, Galla JD, Lansman SL, Mendelson DS, Quintana CS, Griepp RB. Significance of distal false lumen after type A dissection repair. Ann Thorac Surg 1994;57:820 – 825. 16. Kawamoto S, Bluemke DA, Traill TA, Zerhouni EA. Thoracoabdominal aorta in Marfan syndrome: MR imaging findings of progression of vasculopathy after surgical repair. Radiology 1997;203:727–732. 17. Leach SD, Toole AL, Stern H, De Natale RW, Tilson D. Effect of -adrenergic blockade on the growth-rate of abdominal aortic aneurysms. Arch Surg 1988;123:606 – 609. 18. Schor JS, Yerlioglu E, Galla JD, Lansman SL, Ergin MA, Griepp RB. Selective management of acute type B aortic dissection: long-term follow-up. Ann Thorac Surg 1996;61:1339 –1341. 19. Coady MA, Rizzo JA, Hammond GL, Mandapati D, Darr U, Kopf GS, Elefteriades JA. What is the appropriate size criterion for resection of thoracic aortic aneurysms? J Thorac Cardiovasc Surg 1997;113:476 – 491. 20. Hirose Y, Hamada S, Takamiya M, Imakita S, Naito H, Nishimura T. Aortic aneurysm: growth rates measured with CT. Radiology 1992;185:249 –252. 21. Fattori R, Descovich B, Bertaccini P, Celletti F, Caldarera I, Pierangeli A, Gavelli G. MRI evaluation of composite graft replacement of the ascending aorta: leakage detection by gd-DTPA enhancement. Radiology 1999;212:573– 577. 22. Pucillo AL, Schechter AG, Moggio RA, Kay RH, Tenner MS, Herman MV. Postoperative evaluation of ascending aorta prosthetic conduits by magnetic resonance imaging. Chest 1990;97:106 –116. 23. Sakuma H, Bourne MW, O’Sullivan M, Merrick SH, Ullyot DJ, Chatterjee K, Shimakawa A, Foo TK, Higgins CB. Evaluation of thoracic aortic dissection using breath-holding cine MRI. J Comput Assist Tomogr 1996;20:45–50.
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