False lumen patency as a predictor of late outcome in aortic dissection

Aortic dissection (AD) is a disease with a high-risk of mortality. Late deaths are often related to complications in nonoperated aortic segments. Between 1984 and 1996, we retrospectively analyzed the data of 109 patients with acute AD (81 men and 28 women; average age 61 ± 14 years). All imaging examinations were reviewed, and a magnetic resonance imaging examination was performed at the time of the study. Aortic diameters were measured on each aortic segment. Predictive factors of mortality were determined by Cox’s proportional hazard model, in univariate and multivariate analyses, using BMDP statistical software. Follow-up was an average of 44 ± 46 months (range 24 to 164). Actuarial survival rates were 52%, 46%, and 37% at 1, 5, and 10 years, respectively, for type A AD versus 76%, 72%, and 46% for type B AD. Predictors of late mortality were age >70 years and postoperative false lumen patency of the thoracic descending aorta (RR 3.4, 95% confidence intervals 1.20 to 9.8). Descending aorta diameter was larger when false lumen was patent (31 vs 44 mm; P = 0.02) in type A AD. Furthermore, patency was less frequent in operated type A AD when surgery had been extended to the aortic arch. Thus, patency of descending aorta false lumen is responsible for progressive aortic dilation. In type A AD, open distal repair makes it possible to check the aortic arch and replace it when necessary, decreases the false lumen patency rate, and improves late survival.     

Surgical treatment of aortic dissection. Value of echocardiography and MRI for long-term follow-up

Twenty-five patients aged 31 to 74 years (average 50 years) operated for type A aortic dissection (type I: 19 cases, type II: 6 cases) were included in this study. Surgical repair only concerned lesions of the ascending aorta. The hospital mortality was 20 per cent (5 cases), and usually secondary to extension of the dissection. With the exception of 2 late deaths, all patients were followed up for an average of 3.5 years. A late assessment including nuclear magnetic resonance imaging of the thoracic aorta was obtained in 17 of the 18 survivors. These investigations confirmed the good result of repair of the ascending aorta, the uselessness of systematic aortic valve replacement and the palliative nature of repair of type I dissection as 80 per cent of patients had a persistent patent false lumen in the distal aorta.     

Expanding false lumen in the abdominal aorta 5 years after endovascular repair of a type B aortic dissection: successful exclusion of 3 distal re-entry sites.

PURPOSE: To report endovascular treatment of an expanding aneurysmal false lumen several years after successful stent-graft deployment in the descending thoracic aorta for type B aortic dissection. CASE REPORT: A 54-year-old woman who had a stent-graft placed at the entry site of a type B aortic dissection 5 years prior presented with abdominal discomfort and palpable abdominal mass. Successful remodeling of the thoracic aorta was demonstrated by computed tomography; however, a false lumen aneurysm in the abdominal aorta had expanded from 4.8 to 6.5 cm and caused symptoms. She was successfully treated with 3 additional stent-grafts at 3 re-entry sites. Six months after the procedure, the false lumen aneurysm was completely excluded. CONCLUSIONS: Endovascular repair of the re-entry sites can prevent further expansion of false lumen aneurysm, which occurs in some patients with type B dissection treated with stent-grafts.     

Restoration of the thoracic aorta in Type A dissection with hybrid prosthesis

Following successful repair of Type A dissection, late morbidity and mortality depend on the progression of residual chronic Type B dissection. To avoid the development of late aneurysms of the descending thoracic aorta, a persistent aortic false lumen around the stent-graft can be prevented by remodeling the thoracic aorta. Ten consecutive patients (mean age: 56 years) with acute Type A dissection underwent a "frozen elephant trunk operation" with the E-vita hybrid prosthesis, under deep hypothermic circulatory arrest, between October 2009 and April 2010. The thoracic aorta was restored to its original size. Computed tomography was used to size the aortic diameter. All patients survived and were routinely discharged. Postoperative computed tomography showed no remaining false lumen and no distal organ ischemia in any patient. No new neurological complication was recorded. Two patients suffered postoperative pulmonary arterial embolism; one underwent embolectomy. Restoration of the thoracic aorta is a safe procedure to close the false lumen during the primary operation for acute Type A dissection. However, the diameter of the stent should reflect the overall aortic size, independent of the diameter of the true lumen.     

Midterm results of aortic diameter outcomes after thoracic stent-graft implantation for aortic dissection: a multicenter study.

PURPOSE: To evaluate aortic diameter outcomes after stent-graft implantation for aortic dissection in the descending thoracic aorta. METHODS: Fifty patients with type A dissection after ascending aortic surgery (n = 10), type B dissection (n = 34), or intramural hematoma (n = 6) underwent stent-graft repair in 3 centers. Thrombosis and aortic diameter were analyzed by computed tomographic angiography at different levels of the aorta before stent-graft implantation, at discharge, and at follow-up. Measurements were standardized. RESULTS: In all, 67 stent-grafts were implanted for acute (n = 18) and chronic (n = 32) dissection. Stent-graft placement was successfully performed with high technical success (100%) despite 4 major complications (iliac thrombosis in 2 cases, aortic rupture, and a type A dissection) in 3 (6%) patients. Complete thrombosis of the thoracic false lumen was observed in 42% and 63% of cases at discharge and at follow-up (mean 15 months), respectively. At follow-up, the diameters of the entire aorta (mean 5 mm, p < 0.05) and the false lumen (mean 11 mm, p < 0.0001) decreased. Diameters of the abdominal aorta remained stable in association with persistent false lumen perfusion at this level. Aortic diameter results were better in the subgroup of patients with intramural hematoma compared to patients with Marfan syndrome. Three early deaths unrelated to the stent-graft procedure occurred; 2 patients with partial thrombosis of the false lumen died in follow-up secondary to aortic diameter growth. CONCLUSION: Complete thrombosis of the false lumen by stent-graft coverage of the entry tear results in decreased diameter of the entire aorta. In patients with partial thrombosis of the false lumen, the aneurysm continues to enlarge.     

Provisional extension to induce complete attachment after stent-graft placement in type B aortic dissection: the PETTICOAT concept.

PURPOSE: To report the use of a technique (PETTICOAT: provisional extension to induce complete attachment) to obliterate sustained abdominal false lumen flow and pressurization despite successful stent-graft sealing of the thoracic entry tear in patients with complicated type B aortic dissection. METHODS: Of 100 initial patients subjected to stent-graft repair for complex type B aortic dissection with thoracoabdominal extension, 12 patients (10 men; mean age 58.7 years, range 44-76) demonstrated distal true lumen collapse and a perfused abdominal false lumen despite successful sealing of the proximal tears. As an adjunctive or staged procedure, a scaffolding stent was placed for distal extension of the previously implanted stent-graft. In each case, a Sinus aortic stent, Fortress stent, or a Z-stent system was customized with maximum 2-mm oversizing versus the original stent-graft diameter. Magnetic resonance or computed tomographic angiography was performed at discharge, at 3 months, and then annually to determine false channel thrombosis, true and false lumen dimensions, and re-entry flow. RESULTS: Delivery was successful in all cases (100%). The compressed distal true lumen (mean 4+/-3 mm) was reconstructed to a mean width of 21+/-3 mm, and malperfusion was abolished without any obstruction of the abdominal side branches. At up to 1-year follow-up, there were no signs of expansion or distal progression of the scaffolded dissected aorta. All patients with complete thoracic thrombosis showed evidence of improved aortic remodeling; 1 patient with no false lumen thrombosis died at 11 months from thoracoabdominal aortic rupture. CONCLUSION: The PETTICOAT technique may offer a safe and promising adjunctive endovascular maneuver for patients with distal malapposition of the dissecting membrane and false lumen flow. The technique can both abolish distal true lumen collapse and enhance the remodeling process of the entire dissected aorta.     

Long-term predictors of descending aorta aneurysmal change in patients with aortic dissection.

OBJECTIVES: We sought to demonstrate the long-term natural course of descending aorta dilation after acute aortic dissection (AD) and identify early predictors for late aneurysmal change. BACKGROUND: Aneurysmal dilation of the aorta is a critical late complication in AD patients. METHODS: Contrast-enhanced computed tomography (CT) was performed during the acute phase in 100 AD patients, comprising 51 type 1 who underwent ascending aorta surgery and 49 type 3 AD patients. Clinical observation was conducted for 53 +/- 26 months, and CT was repeated for 31 +/- 27 months. RESULTS: Aneurysm (diameter > or =60 mm) occurred in 14.4%, 8.2%, 4.1%, and 3.1% of patients at the upper descending thoracic aorta (UT), mid descending thoracic aorta (MT), lower descending thoracic aorta (LT) and abdominal aorta (AA), respectively. Of 53 patients in whom CT was repeated for > or =2 years, the rates of aorta diameter enlargement at the UT, MT, LT, and AA levels were 3.43 +/- 3.66 mm/year, 3.21 +/- 2.70 mm/year, 2.62 +/- 2.19 mm/year, and 1.93 +/- 3.13 mm/year, respectively (p < 0.01), and aneurysm developed in 15 (28%). The initial false lumen diameter at the UT, the aorta diameter at the MT, and Marfan syndrome were independent predictors of late aneurysm. A > or =22-mm initial false lumen diameter at the UT predicted late aneurysm with a sensitivity of 100% and a specificity of 76%. The patients with initial UT false lumen diameter > or =22-mm (n = 42) showed higher event rate (aneurysm or death) than others (n = 58) (p < 0.001). CONCLUSIONS: The UT is the major site of late aneurysmal dilation. A large UT false lumen diameter on the initial CT portends late aneurysm and adverse outcome warranting early intervention.     

Endovascular stent-graft repair of aortic dissection

Between October 2000 and January 2002, 9 consecutive male patients with subacute or chronic aortic dissection underwent stent-graft placement. The indication for surgery was continuous pain or aneurysm development. One patient had a type A dissecting aortic aneurysm with a primary tear in the ascending thoracic aorta; the other 8 had type B dissection. Placement of an endovascular stent-graft was technically successful in 8 patients, and one underwent an open procedure for abdominal aortic fenestration. The entry site was sealed and the false lumen disappeared in 8 cases, and thrombosis of the false lumen was obtained. Rupture of an iliac artery dissecting aneurysm occurred in one patient 2 days after stent-graft placement; abdominal aortic fenestration with prosthetic replacement of the distal abdominal aorta was performed. One patient died of myocardial infarction 3 days after the stent-graft procedure. During a mean follow-up period of 7 months (1-16 months), one patient died of acute myocardial infarction at 11 months. It was concluded on the basis of these short-term results that endovascular repair of aortic dissection is a promising treatment, and abdominal aortic fenestration is a useful adjuvant procedure.     

Risk factors for descending aortic aneurysm formation in medium-term follow-up of patients with type A aortic dissection

BACKGROUND: After surgery to repair a type A aortic dissection, most late complications and mortality result from descending aorta-related problems. This study was performed to determine the risk factors leading to descending aortic aneurysm formation and late mortality in patients undergoing the type A aortic dissection operation. METHODS: The medical records of patients who survived the operation for type A aortic dissection between 1984 and 1998 were reviewed. There were 144 patients (95 men and 49 women), ranging in age from 24 to 78 years (mean age, 52 years). Most patients were acutely ill, 15 patients were in shock, and 54 patients had cardiac tamponade at the time of the surgical procedure. One hundred thirty-seven patients had ascending aortic replacement only, and of the other 6 patients 2 had hemiarch and 4 had total arch replacement using the elephant trunk technique. The aortic valve was replaced in 23 patients, resuspended in 100, and untouched in 21. Twenty-four risk factors were evaluated in statistical analyses for the prediction of descending aortic aneurysm formation and 3-year mortality. Risk factors were investigated using univariate and multiple logistic regression and survival analyses. RESULTS: The 3-year, 5-year, and 8-year cumulative survival rates were 96.2%, 89.1%, and 80.0%, respectively. The 3-year, 5-year, and 8-year cumulative survival rates, free from descending aortic aneurysm formation or descending aorta operation, were 74.7%, 58.6%, and 43.0%, respectively. Multivariate analysis confirmed that patent false lumen and initial descending aortic diameter were statistically significant risk factors for descending aortic aneurysm formation. CONCLUSIONS: The medium-term survival rate of patients who received operations for type A aortic dissection was satisfactory, despite the high incidence of descending aortic aneurysm formation. The intimal entry site over the aortic arch that was resected during the first operation could decrease the patency rate of a false lumen over the descending aorta. In the absence of a patent false lumen over the descending aorta, the chance of descending aortic aneurysm formation or operation is lessened, and the late survival rate is increased.     

Endovascular treatment of thoracic aortic disease: mid-term follow-up.

OBJECTIVE: The aim of this study was to evaluate the mid-term follow-up in a cohort of patients with acute or chronic descending aortic disease treated by stent-graft repair. BACKGROUND: Since 1999, endovascular stent-graft placement has been reported as an alternative treatment to surgical approach for a variety of thoracic aortic diseases; however, results beyond initial short-term follow-up are not widely available for the broad range of applications. METHODS: From March 2001, 43 consecutive patients with traumatic aortic transection (group A = 16) and complicated type B aortic dissection or aneurysm (group B = 27) underwent stent-graft implantation. All patients underwent computed tomography (CT) scan as preoperative assessment and in 26 a transesophageal echo (TEE) exam was performed. RESULTS: Technically successful stent-graft deployment was achieved in all patients. No patient required surgical conversion and no cases of paraplegia occurred. The overall in-hospital mortality was 9.3%. A residual endoleak (type II) was detected in one group B patient who was managed conservatively. The mean follow-up was 29 +/- 8 months (range 10-48 months). No patient died during late follow-up after hospital discharge. At 12 months, one patient (2.5%) who had stent graft repair of an aortic dissection developed an asymptomatic type I endoleak. Three asymptomatic patients with chronic dissection had a persistent retrograde perfusion of the thoracic false lumen via a distal tear(s) in the dissection septum. CONCLUSION: Our results of stent-graft treatment of complicated and uncomplicated diseases of the descending aorta confirms that this alternative to open repair is a safe, less invasive, and relatively low risk approach. Medium-term follow-up results suggest that it is effective and durable therapy with low associated mortality and morbidity rates.     

Acute and subacute dissection of the thoracic aorta: diagnostic importance of magnetic resonance tomography]

The purpose of this study was to retrospectively assess the reliability of ECG-triggered magnetic resonance imaging (MRI) for the diagnosis of acute and subacute thoracic aortic dissection and associated clinical epiphenomena. 67 patients were subjected to MRI; the diagnostic results were compared with morphological standards. 25 patients had type A, 12 patients type B dissection. In 30 cases a dissection was excluded. 17 patients with aortic dissection had acute onset of symptoms, 10 patients had subacute onset of symptoms. 17 patients revealed thrombosis of the false lumen, which was found in the descending aorta in 59% of the cases. Aortic regurgitation and pericardial effusion was most often associated with type A dissection (Table 1). Three patients were studied while on mechanical ventilation. Scan time for MRI ranged from 15 to 71 minutes with an average of 46 +/- 18 minutes. In this series no deleterious events were encountered related to MRI diagnostics. In contrast to previously published data using other noninvasive techniques the sensitivity of MRI was 100% for detecting a dissection in the ascending segment of the thoracic aorta. Moreover, the specificity of MRI for a dissection was 100% and thus higher than previously published data using transesophageal echocardiography. Sensitivity and specificity for detection and correct classification of type B dissection was 100% and 100% respectively (Table 2). In addition, MRI proved to be sensitive in detecting the formation of thrombus material in the false lumen of the ascending aorta (92%), the aortic arch (100%) and the descending segment (88%). Specificity for exclusion of suspected thrombus material even proved to be slightly higher with 100% in the ascending and descending aorta and 96.1% in the aortic arch (Table 3). The site of entry to a dissection was detected in 78%, with a sensitivity of 76% in the ascending and 92% in the descending aorta. The involvement of side branches in the dissecting process was identified in 60%. There were no false positive findings concerning side branch involvement. Aortic regurgitation and pericardial effusion were detected in 100% and 100%, respectively (Tables 1 and 2). MRI performed even in acute cases proved to be a atraumatic, safe and highly sensitive method to identify and classify acute and subacute dissections of the entire thoracic aorta. Limited patient access was not associated with an increased risk and mechanical ventilation did not interfere with MRI. These results may establish MRI as a valid and promising noninvasive technique to establish the diagnosis in patients with thoracic aortic dissection.(ABSTRACT TRUNCATED AT 400 WORDS)     

Early and late outcomes of acute type A aortic dissection: analysis of risk factors in 487 consecutive patients.

AIMS: The purpose of this retrospective study was to assess the risk factors for the early and late outcome of the surgical treatment of acute type A aortic dissection, in terms of mortality and morbidity. METHODS AND RESULTS: From 1976 to 2003, 487 patients with acute type A aortic dissection treated surgically were enrolled. Twenty-five pre-operative and intra-operative variables were analysed to identify conditions influencing early and late morbidity and early mortality. The in-hospital mortality rate including operative death was 22% (107 patients). Multivariable analysis indicated that pre-existing cardiac disease (RR=3.7, 95% CI=1.8-7.4) and cardiopulmonary resuscitation (RR=6.8, 95% CI=2.3-20.2) were independent predictors of in-hospital death. The causes of in-hospital mortality were low cardiac output in 32 patients (6.6%), major brain damage in 24 patients (5.9%), haemorrhage in 11 patients (2.2%), sepsis in nine patients (1.8%), visceral ischaemia in eight patients (1.6%), multiple organ failure in seven patients (1.4%), rupture of the thoracic aorta in six patients (1.2%), respiratory failure in six patients (1.2%), and four intra-operative deaths. The follow-up was 100% complete. The actuarial survival was 94.9+/-1.2% and 88.1+/-2.6%, at 5 and 10 years, respectively. CONCLUSIONS: Patients' pre-operative co-morbidities and dissection-related complications significantly affect early and late survival and morbidity after surgical treatment of acute type A aortic dissection.     

Ambulatory follow-up of aortic dissection by transesophageal two-dimensional and color-coded Doppler echocardiography

Follow-up of 18 patients with aortic dissection (five with type I, one with type II, 11 with type III dissection according to DeBakey) by transesophageal, two-dimensional and color-coded Doppler echocardiography showed a persistence of the false lumen in five of seven patients (71%) after surgery and in nine of 11 patients (82%) after medical therapy. In two patients treated with surgery, the dissected part of the aorta had been resected, whereas in two patients treated medically, a progressive and complete obliteration of the false lumen was observed. In the false lumen, thrombus formation was absent in four, localized in four, and progressive in six patients. Flow within the false lumen could be registered in 14 patients, and two distinct flow patterns were differentiated (laminar biphasic flow or slowly circulating flow). Persisting intimal tears were visualized by two-dimensional echocardiography in four patients, whereas color-coded Doppler showed an additional one to three intimal tears in the descending aorta in 10 patients. Flow across these intimal tears was biphasic in 75% of patients; that is, systolic flow was directed from the true to the false lumen with diastolic flow reversal. Unidirectional flow was detected in 25% of the communications, directed in 20% from the true to the false lumen, serving as an entry only and in one (5%) as reentry only. Additional information concerning complications like extension of the dissection (one of 18 patients), localized dilatation of the regurgitation (three of 18 patients) were detected by this method. Concerning the morphologic findings and the detection of flow characteristics, the transesophageal approach was superior to conventional echocardiography especially in the descending thoracic aorta. Thus, transesophageal two-dimensional and color-coded Doppler echocardiography seems to be an ideal method not only for the easy detection of aortic dissection but also for follow-up.     

Medical vs surgical treatment of acute aortic dissection in an intensive care unit

To determine which therapeutic procedure is most appropriate for which type of aortic dissection, we investigated 146 cases of acute aortic dissection. In the group with dissection of the ascending aorta, 58.6% of patients given medical therapy and 48.8% of patients given surgical therapy died. In the group with dissection of the descending aorta, 14.0% given medical therapy and 50.0% given surgical therapy died. High mortality in the medical group with type A dissection was caused by delayed operation. Better survival was achieved in treated than surgically treated patients with acute distal dissection. In patients with cardiac tamponade, aortic regurgitation, hemothorax/hemo-mediastinum, visceral ischemia and peripheral ischemia, mortalities following medical treatment were fairly high. Surgical treatment brought on improvement in mortality in these groups. However, in the cases complicated by renal dysfunction, the mortality in the surgical group was higher than that in the medical group. 42 patients (28.8%) had no evidence of any complication and only 6 (14.3%) died. In 20 cases (47.6%) of uncomplicated dissection, no blood flow was observed in the false lumen. In cases with open false lumen, the following abnormal findings were more conspicuous: thrombocytopenia, decreased level of fibrinogen, increased fibrin degradation product and soluble fibrin monomer complex. However, these changes seem to be minimal in cases with thrombosed false lumen. The measurement of coagulation factors may be one useful method to determine which therapeutic procedure is most suitable.     

Predictors of in-hospital mortality in patients with acute aortic dissection

BACKGROUND: If acute aortic dissection is a highly lethal disease. There were few reports addressing predictors of in-hospital mortality of this disease in southern Taiwan. METHODS: If from January 1, 1989, to December 31, 2001, patients with acute aortic dissection were enrolled. Patient demographics, history, clinical characteristics, and laboratory examinations were reviewed. Univariate testing followed by logistic regression analysis was performed to identify the predictors of in-hospital mortality. RESULTS: If in total, 198 (146 male) patients with mean age of 60.7+/-11.6 years were enrolled. The in-hospital mortality rate was 34.8% in overall patients, 58.8% for type A dissection, and 14.8% for type B dissection. There were five independent predictors of in-hospital mortality: presence of hypertension [odds ratio (OR)=0.09, 95% confidence interval (CI)=0.02-0.36, p<0.001], type A dissection (OR=8.26, 95% CI=3.44-19.60, p<0.001), probable extravasation (pericardial effusion in type A dissection or left side pleural effusion in patients with involvement of descending thoracic aorta) (OR=2.70, 95% CI=1.14-6.41, p=0.024), visible intimal flap in ascending aorta in trans-thoracic echocardiography (OR=4.46, 95% CI=1.58-12.60, p=0.005), and acute renal deterioration (OR=3.85, 95% CI=1.36-10.87, p=0.011). CONCLUSIONS: If acute aortic dissection, especially type A, is with high mortality in southern Taiwan. There are five independent predictors of in-hospital mortality found in current analysis. Our result may remind doctors to find out their patients at high risk. Trans-thoracic echocardiography is a useful tool to find out patients at high risk because it is easily performed to check if there is pericardial effusion or visible intimal flap in ascending aorta.     

Fate of the native aorta after repair of acute type A dissection: a magnetic resonance imaging study.

OBJECTIVE--To determine late patency of the aortic false lumen and propensity for aneurysm formation after repair of type A dissection. DESIGN--Retrospective follow up study. SETTING--Regional cardiac surgical unit. PATIENTS--28 patients after repair of type A dissection. METHODS--Magnetic resonance imaging (MRI) was performed between 6 weeks and 12 months after operation. RESULTS--A patent distal false lumen with demonstrable blood flow was found in 22 patients (78%). Only six patients had complete obliteration of the false lumen by thrombus. The conduct of operation did not influence this. Nine patients (32%) showed aneurysmal dilatation of the false lumen and three had a repeat operation. CONCLUSIONS--So-called "successful repair" of aortic dissection does not obliterate the distal false lumen. MRI is a safe and effective radiological procedure for determining patency and dilatation in the false lumen. Patients with type A dissection with blood flow in the false lumen should be studied every 6 months to look for aneurysmal dilatation.     

Combination of color Doppler and transesophageal echocardiography in emergency diagnosis of type I aortic dissections

We report on the use of colour Doppler- and transesophageal echocardiography in 2 patients with acute type I aortic dissection according to DeBakey. Using transesophageal echocardiography we obtained information on the extension and the entry site of the dissection without interfering with respiration and external thorax configuration. Using colour Doppler we were able to differentiate between the true and false lumen in the thoracic and abdominal aorta due to characteristic phasic flow patterns. In one patient the site of the entry tear of the intimal flap was localized by this method. Furthermore, a noninvasive semiquantitative evaluation of accompanying aortic regurgitation was possible. Colour Doppler gives additional information in the emergency diagnosis of patients with aortic dissection.     

Value of transesophageal echocardiography combined with computed tomography for assessing repaired type A aortic dissection.

Thirty-two patients with repaired type A aortic dissection were examined by transthoracic echocardiography (TTE) (n = 32), transesophageal echocardiography (TEE) (n = 30), computed tomography (CT) (n = 29), or a combination of all 3, to assess course and complications as a function of the surgical procedure. The mean follow-up period was 55.7 months (range 3 to 132). Surgery consisted of a replacement of the ascending aorta in 25 patients (group 1) with extension to the transverse aorta in 7 (group 2). The transverse diameter of the aorta, the persistence of the false lumen, thrombus formation and flow dynamics in the false lumen were evaluated by TEE. Ten patients (31%) had a dilation in the initial ascending aorta (sinus of Valsalva aneurysm in 6 patients, and a false aneurysm in the other 4). Three of 4 patients with a proximal pseudoaneurysm underwent operation after TEE and CT evaluation. In the descending thoracic aorta, there was good agreement between TEE and CT scan determinations of transverse vessel diameter. Persistence of flow within the false lumen was significantly more frequent in patients with a dilated aorta (p < 0.05), whereas thrombosis was seen more often and false lumen less often in patients with nondilated aorta. No significant differences in vessel status or outcome were observed between the 2 groups, although this may have been due to the small size of group 2. TEE is thus a well-tolerated method for postoperative follow-up of type A aortic dissection whatever the type of surgery. For the upper ascending aorta, CT provided sufficient data.     

Diagnosis of thoracic aortic dissection. Magnetic resonance imaging versus transesophageal echocardiography.

BACKGROUND. Aortic dissection requires prompt and reliable diagnosis to reduce the high mortality. The purpose of this study was to assess the reliability of both ECG-triggered magnetic resonance imaging (MRI) and transesophageal two-dimensional echocardiography combined with color-coded Doppler flow imaging (TEE) for the diagnosis of thoracic aortic dissection and associated epiphenomena. METHODS AND RESULTS. Fifty-three consecutive patients with clinically suspected aortic dissection were subjected to a dual noninvasive imaging protocol in random order; imaging results were compared and validated against the independent morphological "gold standard" of intraoperative findings (n = 27), necropsy (n = 7), and/or contrast angiography (n = 53). No serious side effects were encountered with either imaging method. In contrast to a precursory screening transthoracic echogram, the sensitivities of both MRI and TEE were 100% for detecting a dissection of the thoracic aorta irrespective of its location. The specificity of TEE, however, was lower than the specificity of MRI for a dissection (TEE, 68.2% versus MRI, 100%; p less than 0.005), which resulted mainly from false-positive TEE findings confined to the ascending segment of the aorta (TEE, 78.8% versus MRI, 100%; p less than 0.01). In addition, MRI proved to be more sensitive than TEE in detecting the formation of thrombus in the false lumen of both the aortic arch (p less than 0.01) and the descending segment of the aorta (p less than 0.05). There were no discrepancies between the two imaging techniques in detecting the site of entry to a dissection, aortic regurgitation, or pericardial effusion. CONCLUSIONS. Both MRI and TEE are atraumatic, safe, and highly sensitive methods to identify and classify acute and subacute dissections of the entire thoracic aorta. TEE, however, is associated with lower specificity for lesions in the ascending aorta. These results may still favor TEE as a semi-invasive diagnostic procedure after a precursory screening transthoracic echogram in suspected aortic dissection, but they establish MRI as an excellent method to avoid false-positive findings. Anatomic mapping by MRI may emerge as the most comprehensive approach and morphological standard to guide surgical interventions.     

Detection of dissection of the thoracic aorta: improved specificity by magnetic resonance tomography in comparison with echocardiography techniques]

The purpose of this study was to assess the reliability of conventional transthoracic and transoesophageal two-dimensional echocardiography combined with color-coded Doppler flow imaging (TEE) and ECG-triggered magnetic resonance imaging (MRI) for the diagnosis of thoracic aortic dissection and associated epiphenomena. A total of 53 patients with clinically suspected aortic dissection were subjected to a transthoracic and transoesophageal ultrasound examination and magnetic resonance imaging; the results of each imaging modality were compared and validated against the morphological standards of contrast angiography (n = 53) and/or intraoperative findings (n = 27) or autopsy (n = 7). In this series no deleterious events were encountered with either non-invasive imaging method. In contrast to conventional echocardiography the sensitivities of both MRI and TEE were 100% for detecting a dissection of the thoracic aorta, irrespective of its location. However, the specificity of TEE was lower than the specificity of MRI for a dissection (TEE 68.2% versus MRI 100%; p less than 0.005), which resulted from false positive TEE findings mainly confined to the ascending segment of the aorta (specificity of TEE 78.8% versus 100% by MRI; p less than 0.01). In addition, MRI proved to be more sensitive than TEE in detecting the formation of thrombus in the false lumen of both the aortic arch (p less than 0.01) and the descending segment of the aorta (p less than 0.05). There were no discrepancies between the two imaging techniques in detecting the site of entry to a dissection, aortic regurgitation or pericardial effusion. Both MRI and TEE are atraumatic, safe, and highly sensitive methods to identify and classify acute and subacute dissections of the entire thoracic aorta. However, TEE is associated with lower specificity for lesions in the ascending aorta. These results may still favor TEE after a precursory screening transthoracic echogram in suspected aortic dissection, but will establish MRI as an excellent method to avoid false positive findings. Anatomical mapping by MRI may emerge as a promising comprehensive approach and, eventually, as a morphological standard to guide surgical interventions.