Background The molecular mechanisms leading to ascending thoracic aortic aneurysms (ATAAs) remain unknown. We hypothesized that alterations in expression levels of specific fibrillar collagens occur ...during the aneurysmal process. Methods Surgical samples from ascending aortas from patients with degenerative ATAAs were subdivided by aneurysm diameter: small, 5 to 6 cm; medium, 6 to 7 cm; and large, greater than 7 cm; and compared with nonaneurysmal aortas (mean diameter, 2.3 cm). Results Histology, immunofluorescence, and electron microscopy demonstrated greater disorganization of extracellular matrix constituents in ATAAs as compared with control with an increase in collagen α1(XI) within regions of cystic medial degenerative lesions. Real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR) showed collagens type V and α1(XI) were significantly and linearly increased in ATAAs as compared with control ( p < 0.001). There was no change in the messenger ribonucleic acid (mRNA) expression levels of collagens type I and III. Western blot analysis showed collagens type I and III were significantly decreased and collagens α1(XI) and V were significantly increased and were linearly correlated with the size of the aneurysm ( p < 0.001 for both). Conclusions These results demonstrate that increased collagen α1(XI) and collagen V mRNA and protein levels are linearly correlated with the size of the aneurysm and provide a potential mechanism for the generation and progression of aneurysmal enlargement.
Abdominal aortic aneurysm (AAA) is a common and lethal disease. AAAs are associated with atherosclerosis, chronic inflammation, and extracellular matrix degradation. The aim of this study was to ...determine whether treatment with simvastatin can influence the development of experimental aortic aneurysms in a rabbit model.
A total of 76 rabbits were randomized in four groups: in group I (n = 12), where the abdominal aortas were exposed to 0.9% NaCl, and in group II (n = 24), group III (n = 24) and group IV (n = 18), where the aortas were exposed to CaCl2 0.5 mol/L for 15 minutes after laparotomy. Group III received 2 mg/kg simvastatin daily starting 7 days before laparotomy, and in group IV, the daily treatment with simvastatin started 7 days after laparotomy. Animals were sacrificed at intervals of first, second, third, and fourth week to obtain measurements of aortic diameter and histological examination. Moreover, immunohistochemistry was used in order to examine the relative distribution of matrix metalloproteinases (MMPs) 2 and 9 (MMP-2 and MMP-9, respectively) and tissue inhibitor 1 of MMPs within the aortic aneurysms.
The increase of aortic diameter in animals of group I ranged from 4.6% to 7.6%; in group II, from 41% to 85% (P < 0.001 vs. group I); in group III, from 9% to 18% (group II vs. group III, P < 0.001); and in group IV; from 36% to 38%. Moreover, aortic specimens of group II presented a statistically significant increase in MMP-2 and MMP-9 immunoexpression compared with other groups (I, III, IV) (P < 0.05 for all comparisons), with the exception of animals of group IV at the end of second week. Immunoreactivity of tissue inhibitor 1 of MMPs was not statistically different among groups II, III, and IV.
Simvastatin may prove clinically significant in suppressing the development and expansion of AAAs and, thereby, in reducing the risk of rupture and the need for repair.
Hypothermic cardiopulmonary bypass with intervals of circulatory arrest is a useful adjunct during operations on the descending thoracic aorta and distal aortic arch when severe aortic disease ...precludes placement of clamps on the aorta. Hypothermia also has a marked protective effect on spinal cord function during periods of aortic occlusion.
Fifty-one patients (age range, 22 to 79 years) with descending thoracic or thoracoabdominal aortic disease had resection and graft replacement of the diseased aortic segments using hypothermic cardiopulmonary bypass and intervals of circulatory arrest in situations where the location, extent, or severity of disease precluded placement of clamps on the proximal aorta (8 patients) or (in 43 patients) when extensive thoracic (11) or thoracoabdominal (32) aortic disease was present and the risk for development of spinal cord ischemic injury and renal failure was judged to be increased. Patent intercostal (below T-6) and upper lumbar arteries were attached to the graft whenever possible.
Thirty-day mortality was 9.8% (5 patients). Paraplegia occurred in 2 and paraparesis in 1 of the 46 30-day survivors (6.5%). Among the 27 operative survivors with thoracoabdominal aneurysms, paraplegia occurred in 1 of 12 with Crawford type I (8%), 0 of 10 with type II, and 1 of 5 with type III aneurysms (20%). Paraplegia occurred in none of the 12 patients with aortic dissection and in 2 of the 15 patients with degenerative aneurysms. Renal failure requiring dialysis occurred in 1 (2.2%) of the 46 30-day survivors.
Hypothermic circulatory arrest is a valuable adjunct for the treatment of complex aortic disease involving the aortic arch and thoracoabdominal aorta. In patients with thoracoabdominal aneurysms, its use has been associated with a low incidence of renal failure and an incidence of paraplegia/paraparesis in traditionally high-risk subsets (type I and II aneurysms, aortic dissection), which may be less than that observed with other surgical techniques.
The future of risk stratification in thoracic surgery Toumpoulis, Ioannis K., MD; Rokkas, Chris K., MD; Chamogeorgakis, Themistocles P., MD
Journal of thoracic and cardiovascular surgery/The Journal of thoracic and cardiovascular surgery/The journal of thoracic and cardiovascular surgery,
07/2008, Letnik:
136, Številka:
1
Journal Article
Objectives: Adult patients with aortic coarctation may have complications after childhood repair. Other adult patients have coarctation and aneurysms of the aorta and the left subclavian artery. The ...optimal management of such cases is not clearly established. We evaluated the role of hypothermic cardiopulmonary bypass and circulatory arrest. Methods: Thirteen adult patients (mean age 38 years) with coarctation and coexisting abnormalities of the aorta and left subclavian artery were treated. Five patients had pseudoaneurysms develop after bypass grafting (n = 3) or patch angioplasty (n = 2). These were detected a mean of 21 years (range 13-44 years) after the initial operation. Four pseudoaneurysms were asymptomatic, and 1 had ruptured. One patient had recurrent coarctation from fibrous obliteration of a 10-mm bypass graft inserted 15 years previously. The remaining 7 patients had aneurysms of the left subclavian artery (n = 5), aneurysms of the ascending aorta and arch (n = 1), or stenosis of the left subclavian artery (n = 1) in combination with moderate or severe coarctation. Resection and interposition graft replacement of the aneurysmal or stenotic aortic segments were performed in all cases with an interval of hypothermic circulatory arrest that averaged 44 ± 5 minutes (range 33-54 minutes). Seven patients had interposition graft replacement of aneurysmal or stenotic left subclavian arteries. Results: There were no in-hospital or late deaths (maximal follow-up 7 years). No patient had brain injury, paralysis, myocardial, respiratory, or renal failure. No patient has evidence of recurrent coarctation or aneurysm formation. Conclusions: Cardiopulmonary bypass with hypothermic circulatory arrest can safely be used in the treatment of complex adult coarctation. It permits accurate delineation of the anatomy with minimal dissection, avoidance of aortic clamping and sacrifice of intercostal arteries, precise interposition graft repair, and adequate protection of vital organs.
J Thorac Cardiovasc Surg 2002;124:155-61
Objective: Management of the enlarged, chronically dissected aorta after previous repair of acute aortic dissection or after a previous cardiac operation may present a formidable technical challenge. ...Marked enlargement of the proximal descending thoracic aorta precludes safe use of staged procedures, including the elephant trunk technique.
Methods: Sixteen patients with chronic type A aortic dissection (mean age, 56 years) underwent resection of the ascending aorta, the aortic arch, and varying segments of the descending thoracic aorta. We used single-stage replacement, with perfusion of the aortic arch first to minimize the duration of brain ischemia, with a bilateral anterior thoracotomy (clamshell) incision. Eleven patients had undergone previous repair of acute type A dissection. Five patients had type A dissection after aortic valve replacement (2 patients) and coronary artery bypass (3 patients). Marked enlargement of the aorta distal to the left subclavian artery precluded a 2-stage repair. The mean interval between the initial and reoperative procedures was 62 months (range, 5-137 months).
Results: There was 1 (6.2%; 70% confidence limits, 0.3%-24.7%) hospital death. Four patients required reoperation for bleeding. One patient required a right ventricular assist device that was successfully removed. Six patients required assisted ventilation for more than 72 hours, and 3 patients required a tracheostomy. All were successfully weaned from ventilatory support. No patient had a stroke or other adverse neurologic outcome.
Conclusion: The single-stage, arch-first replacement technique is a safe and effective procedure for patients who require extensive reoperations for chronic expanding type A dissection.
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