Intimal tear without hematoma: an important variant of aortic dissection that can elude current imaging techniques.
BACKGROUND: The modern imaging techniques of transesophageal echocardiography, CT, and MRI are reported to have up to 100% sensitivity in detecting the classic class of aortic dissection; however, anecdotal reports of patient deaths from a missed diagnosis of subtle classes of variants are increasingly being noted. METHODS AND RESULTS: In a series of 181 consecutive patients who had ascending or aortic arch repairs, 9 patients (5%) had subtle aortic dissection not diagnosed preoperatively. All preoperative studies in patients with missed aortic dissection were reviewed in detail. All 9 patients (2 with Marfan syndrome, 1 with Takayasu's disease) with undiagnosed aortic dissection had undergone >/=3 imaging techniques, with the finding of ascending aortic dilatation (4.7 to 9 cm) in all 9 and significant aortic valve regurgitation in 7. In 6 patients, an eccentric ascending aortic bulge was present but not diagnostic of aortic dissection on aortography. At operation, aortic dissection tears were limited in extent and involved the intima without extensive undermining of the intima or an intimal "flap." Eight had composite valve grafts inserted, and all survived. Of the larger series of 181 patients, 98% (179 of 181) were 30-day survivors. CONCLUSIONS: In patients with suspected aortic dissection not proven by modern noninvasive imaging techniques, further study should be performed, including multiple views of the ascending aorta by aortography. If patients have an ascending aneurysm, particularly if eccentric on aortography and associated with aortic valve regurgitation, an urgent surgical repair should be considered, with excellent results expected. (+info)
Pathogenetic sequence for aneurysm revealed in mice underexpressing fibrillin-1.
Dissecting aortic aneurysm is the hallmark of Marfan syndrome (MFS) and the result of mutations in fibrillin-1, the major constituent of elastin-associated extracellular microfibrils. It is yet to be established whether dysfunction of fibrillin-1 perturbs the ability of the elastic vessel wall to sustain hemodynamic stress by disrupting microfibrillar assembly, by impairing the homeostasis of established elastic fibers, or by a combination of both mechanisms. The pathogenic sequence responsible for the mechanical collapse of the elastic lamellae in the aortic wall is also unknown. Targeted mutation of the mouse fibrillin-1 gene has recently suggested that deficiency of fibrillin-1 reduces tissue homeostasis rather than elastic fiber formation. Here we describe another gene-targeting mutation, mgR, which shows that underexpression of fibrillin-1 similarly leads to MFS-like manifestations. Histopathological analysis of mgR/mgR specimens implicates medial calcification, the inflammatory-fibroproliferative response, and inflammation-mediated elastolysis in the natural history of dissecting aneurysm. More generally, the phenotypic severity associated with various combinations of normal and mutant fibrillin-1 alleles suggests a threshold phenomenon for the functional collapse of the vessel wall that is based on the level and the integrity of microfibrils. (+info)
Observations on the treatment of dissection of the aorta.
The results are presented of treatment in twenty-three patients with dissection of the thoracic aorta, in four of whom it was acute (less than 14 days' duration), and in nineteen chronic (more than 14 days' duration). Sixteen patients had Type I and II dissection (involving the ascending aorta) and five Type III (descending aorta at or distal to the origin of the left subclavian artery); in two, dissection complicated coarctation of the aorta in the usual site. Thirteen patients had aortic regurgitation. Three of the patients with acute dissection were treated medically; two, both with Type I dissection, died, and the third, with Type III, survived. The remaining acute patient was treated surgically and also died. Of the patients with chronic dissection, eight were treated medically and eleven surgically. None of the medical group died in hospital; three died between 3 months and 1 year, and five have survived from periods of 12-72 months. Eleven patients with chronic dissection were treated surgically; four died in hospital at or shortly after operation; and the remaining seven lived for periods of 12-84 months. The presentation, indications for surgical treatment and results are discussed. It is concluded that surgical treatment of chronic dissection may carry a higher initial mortality than medical, but that there may be slightly better overall long term results in the former. As this series was not selected randomly, because patients with complications were selected for surgery, and there are only a few patients in each group, the results do not permit firm conclusion regarding the relative merits of medical and surgical treatment. It is suggested that all patients should initially be treated medically but that surgical treatment should be considered if the dissection continues, if aortic regurgitation is severe, if an aneurysm develops or enlarges, if cardiac tamponade develops or there is evidence of progressive involvement of the branches of the aorta. Attention is drawn to the important syndrome of chronic dissecting aneurysm of the ascending aorta with severe aortic regurgitation which requires definitive surgical treatment and aortic valve replacement. The importance of adequate visualization of the origin and extent of the dissection as a preliminary to surgical treatment is stressed. (+info)
Replacement of the aortic root in patients with Marfan's syndrome.
BACKGROUND: Replacement of the aortic root with a prosthetic graft and valve in patients with Marfan's syndrome may prevent premature death from rupture of an aneurysm or aortic dissection. We reviewed the results of this surgical procedure at 10 experienced surgical centers. METHODS: A total of 675 patients with Marfan's syndrome underwent replacement of the aortic root. Survival and morbidity-free survival curves were calculated, and risk factors were determined from a multivariable regression analysis. RESULTS: The 30-day mortality rate was 1.5 percent among the 455 patients who underwent elective repair, 2.6 percent among the 117 patients who underwent urgent repair (within 7 days after a surgical consultation), and 11.7 percent among the 103 patients who underwent emergency repair (within 24 hours after a surgical consultation). Of the 675 patients, 202 (30 percent) had aortic dissection involving the ascending aorta. Forty-six percent of the 158 adult patients with aortic dissection and a documented aortic diameter had an aneurysm with a diameter of 6.5 cm or less. There were 114 late deaths (more than 30 days after surgery); dissection or rupture of the residual aorta (22 patients) and arrhythmia (21 patients) were the principal causes of late death. The risk of death was greatest within the first 60 days after surgery, then rapidly decreased to a constant level by the end of the first year. CONCLUSIONS: Elective aortic-root replacement has a low operative mortality. In contrast, emergency repair, usually for acute aortic dissection, is associated with a much higher early mortality. Because nearly half the adult patients with aortic dissection had an aortic-root diameter of 6.5 cm or less at the time of operation, it may be prudent to undertake prophylactic repair of aortic aneurysms in patients with Marfan's syndrome when the diameter of the aorta is well below that size. (+info)
Endovascular stent-graft placement for the treatment of acute aortic dissection.
BACKGROUND: The standard treatment for acute aortic dissection is either surgical or medical therapy, depending on the morphologic features of the lesion and any associated complications. Irrespective of the form of treatment, the associated mortality and morbidity are considerable. METHODS: We studied the placement of endovascular stent-grafts across the primary entry tear for the management of acute aortic dissection originating in the descending thoracic aorta. We evaluated the feasibility, safety, and effectiveness of transluminal stent-graft placement over the entry tear in 4 patients with acute type A aortic dissections (which involve the ascending aorta) and 15 patients with acute type B aortic dissections (which are confined to the descending aorta). Dissections involved aortic branches in 14 of the 19 patients (74 percent), and symptomatic compromise of multiple branch vessels was observed in 7 patients (37 percent). The stent-grafts were made of self-expanding stainless-steel covered with woven polyester or polytetrafluoroethylene material. RESULTS: Placement of endovascular stent-grafts across the primary entry tears was technically successful in all 19 patients. Complete thrombosis of the thoracic aortic false lumen was achieved in 15 patients (79 percent), and partial thrombosis was achieved in 4 (21 percent). Revascularization of ischemic branch vessels, with subsequent relief of corresponding symptoms, occurred in 76 percent of the obstructed branches. Three of the 19 patients died within 30 days, for an early mortality rate of 16 percent (95 percent confidence interval, 0 to 32 percent). There were no deaths and no instances of aneurysm or aortic rupture during the subsequent average follow-up period of 13 months. CONCLUSIONS: These initial results suggest that stent-graft coverage of the primary entry tear may be a promising new treatment for selected patients with acute aortic dissection. This technique requires further evaluation, however, to assess its therapeutic potential fully. (+info)
The highs and lows of endovascular aneurysm repair: the first two years of the Eurostar Registry.
The Eurostar Registry was established in 1996 to collate information, from centres across Europe, on the outcome from endovascular grafting of aortic aneurysms. At the end of the first year of the project, data on 430 patients had been entered onto the database. In 420 patients (97.7%), the endografts were deployed without major complications. The 30-day mortality rate was low at 3.4% and deaths were confined mostly to 'high risk' patients with major co-morbidity. Endoleaks, which were present on discharge from hospital in 15.7% of patients, were associated with a significantly increased incidence of continued expansion of the aneurysm sac postoperatively (P < 0.01). Thus the early results confirmed the feasibility and low complication rate of endovascular repair of aneurysms, but a higher than expected incidence of endoleaks. At 2 years, 895 patients had been registered. The rate of early endoleaks remained significantly unchanged but another 18% of patients had developed new endoleaks during the first year of follow-up. Six delayed ruptures had been reported, 3 fatal. There were indications that 'self sealed' endoleaks continued to pressurise the aneurysm sac. Severe distortion of the grafts with kinking and other structural changes associated with postoperative longitudinal shrinking of the aneurysm sac was observed in 69% of patients at 1 year. Clinical complications associated with these changes included late endoleak and graft limb occlusion. Early unrealistic optimism about endovascular aneurysm repair has been replaced with a more realistic understanding of its benefits and limitations as a result of the Eurostar project and other registries. Randomised studies are now required to establish the most appropriate role for this approach, alongside established therapies. (+info)
Increased chymase-dependent angiotensin II formation in human atherosclerotic aorta.
Locally formed angiotensin II (Ang II) and mast cells may participate in the development of atherosclerosis. Chymase, which originates from mast cells, is the major Ang II-forming enzyme in the human heart and aorta in vitro. The aim of the present study was to investigate aortic Ang II-forming activity (AIIFA) and the histochemical localization of each Ang II-forming enzyme in the atheromatous human aorta. Specimens of normal (n=9), atherosclerotic (n=8), and aneurysmal (n=6) human aortas were obtained at autopsy or cardiovascular surgery from 23 subjects (16 men, 7 women). The total, angiotensin-converting enzyme (ACE)-dependent, and chymase-dependent AIIFAs in aortic specimens were determined. The histologic and cellular localization of chymase and ACE were determined by immunocytochemistry. Total AIIFA was significantly higher in atherosclerotic and aneurysmal lesions than in normal aortas. Most of AIIFA in the human aorta in vitro was chymase-dependent in both normal (82%) and atherosclerotic aortas (90%). Immunocytochemical staining of the corresponding aortic sections with antichymase, antitryptase or anti-ACE antibodies showed that chymase-positive mast cells were located in the tunica adventitia of normal and atheromatous aortas, whereas ACE-positive cells were localized in endothelial cells of normal aorta and in macrophages of atheromatous neointima. The density of chymase- and tryptase-positive mast cells in the atherosclerotic lesions was slightly but not significantly higher than that in the normal aortas, and the number of activated mast cells in the aneurysmal lesions (18%) was significantly higher than in atherosclerotic (5%) and normal (1%) aortas. Our results suggest that local Ang II formation is increased in atherosclerotic lesions and that chymase is primarily responsible for this increase. The histologic localization and potential roles of chymase in the development of atherosclerotic lesions appear to be different from those of ACE. (+info)
Effect of nitrous oxide on myogenic motor potentials evoked by a six pulse train of transcranial electrical stimuli: a possible monitor for aortic surgery.
Intraoperative recording of myogenic motor potentials evoked by transcranial electrical stimulation (tcMEP) is a method of monitoring the integrity of the vulnerable motor pathways during thoracoabdominal aortic aneurysm (TAAA) surgery. Deflation of the left lung during TAAA surgery may result in impairment of arterial oxygenation. Ventilation with nitrous oxide may cause further desaturation. We studied the effects of 20%, 40% and 60% nitrous oxide in oxygen on within-patient variability and magnitude of tcMEP in response to six pulse transcranial electrical stimulation during fentanyl-low-dose propofol anaesthesia with partial neuromuscular block. Ten patients (two females; aged 63-74 yr) were studied. After achieving a stable anaesthetic state and before surgery, 10 tcMEP were recorded from the right tibialis anterior muscle during addition of 20%, 40% and 60% nitrous oxide in oxygen in random order. When ventilation with 40% or 60% nitrous oxide in oxygen was performed, there was 50-70% depression of tcMEP amplitude (P < 0.05) and 40-60% reduction in tcMEP area under the curve (P < 0.05) compared with 20% nitrous oxide in oxygen. There was no significant difference in the coefficients of variation for tcMEP between the three nitrous oxide anaesthetic regimens. Our results suggest that increasing doses of nitrous oxide reduce the MEP waveform to six pulse transcranial electrical stimulation, but even with 60% nitrous oxide in oxygen, the tcMEP were recordable and as reproducible as with 20% and 40% nitrous oxide regimens. The method is sufficiently robust for use in aortic surgery. (+info)