Dissection of the aorta: a new approach

There are two generally proposed causes of dissection of the aorta: (1) cleavage caused by blood entering the tear; and (2) haemorrhage that dissects the media and tear secondary to the cleavage. Using analysis of pressures and forces, this article shows that, on some occasions, these mechanisms alone cannot be responsible for causing aortic dissection     

Magnetic resonance imaging of the thoracic aorta

Forty-one patients with a variety of suspected aortic lesions underwent magnetic resonance imaging (MRI) of the thoracic aorta. Patients were separated into 2 groups: Group A included 19 patients who underwent MRI after arteriography for comparison purposes and were evaluated retrospectively. Surgical confirmation was obtained in 9 of these patients. Group B included 22 patients who were studied prospectively because of abnormal chest x-ray, ultrasound or computerized tomographic findings and did not undergo arteriography before MRI. Two patients from this group had surgery. In group A, MRI correlated with the surgical or angiographic findings in 18 of 19 patients (95%). In group B, MRI was considered of diagnostic quality in all patients and no other invasive or noninvasive imaging modalities were needed for diagnosis and treatment. Thus, MRI will replace arteriography in a large proportion of patients with suspected thoracic aortic lesions.     

New imaging technics in dissection of the thoracic aorta

The multiplicity of imaging for investigation of the thoracic aorta requires that the physician choose a strategy adapted to the disorder involved: this is the case, for example with dissection of the aorta. A critical study of the new methods available which include digital angiography; echocardiography; CT scan; magnetic resonance imaging (MRI), should be compared to "the" reference technique of conventional methods: aortography and two-dimensional cineangiography. In addition, the decision must take into account specific characteristics of the disorder: natural history of the disease and anatomopathological form which are useful for the surgeon in case surgery is decided upon. The strategy proposed remains faithful to two-dimensional cineangiography during the first 72 hours of acute dissection because this disorder is a true surgical emergency at this stage if the ascending aorta is involved. Later, or if the ascending aorta does not appear to be involved, MRI has now proven this efficacy as a first-line diagnostic procedure. The judiciousness of preoperative aortography is still the subject of debate.     

Direct videoscopic approach to the descending thoracic aorta for aortic arch endograft delivery: evaluation in a porcine model.

PURPOSE: To examine the feasibility of a direct videoscopic approach to the descending thoracic aorta for endograft delivery to the aortic arch. METHODS: A double purse-string suture was placed on the aorta of 3 pigs via a thoracoscopic approach. Subsequently, the aorta was cannulated in the center of the purse-string. A 22-F delivery catheter was advanced under fluoroscopic control over a guidewire via a trocar into the proximal aorta. After deployment of a tubular endograft, the catheter was withdrawn from the aorta while simultaneously tightening the purse-string suture, without aortic cross clamping. The outcome was evaluated by post implant angiography and autopsy results. RESULTS: The procedure was successfully completed in all animals, with a mean total procedure time of 126 minutes (range 118-137). Mean endograft implantation time from needle puncture to catheter extraction was 27 minutes (range 21-37). Hemostasis was obtained in all animals after withdrawal of the delivery catheter and tightening the purse-string suture. The mean blood loss was 143 mL (range 80-220). Autopsy proved all purse-string sutures to be adequately placed and all endografts deployed in the correct position. CONCLUSION: A direct videoscopic approach to the descending thoracic aorta proved a feasible technique for endograft delivery to the aortic arch in a porcine model.     

Acute dissection of the thoracic aorta. Proposal of a new surgical technic

Acute aortic dissection is a challenging surgical disease. Replacement of the supracoronary aorta alone can be followed by recurrent aneurysm formation at the level of the residual aortic root. The Bentall procedure prevents this late complication but intraoperative haemorrhage may be severe and valve replacement is always mandatory. A new surgical technique is presented which has been adopted in seven consecutive patients with no deaths. With this procedure, strengthening of the aortic root is obtained by inserting three Dacron Double Velour patches "between" the internal and external aortic lamina, one for each sinus of Valsalva. The patches override the coronary ostia which are left wide patent, and are anchored directly to the aortic anulus by single mattress sutures which reduce the size of the anulus. Suspension of the valve leaflets to the patches overriding each other at the commissures together with anuloplasty reestablish valve continency. The two aortic stumps are secured with running sutures over the free edge and a tubular Dacron graft is then anastomosed to them. The procedure reinforces the aortic root, will prevent recurrent aneurysm formation and avoids at the same time valve replacement, when unnecessary, and coronary arteries reimplantation.     

行改进术式预防逆行性A型夹层的效果研究

目的:逆行性A型夹层是升主动脉-头臂血管人工血管转流术+胸降主动脉覆膜支架置入术(d-TEVAR)术后一种高发而致命的并发症,导致d-TEVAR仅在高危弓部病变患者中使用.自体升主动脉与覆膜支架间的顺应性不匹配是导致d-TEVAR术后逆行性A型夹层发生的重要原因之一.本文介绍一种新的方法以求减少逆行性A型夹层的发生.方...     

Percutaneous treatment of thoracic aorta diseases. A multidisciplinary approach

INTRODUCTION AND OBJECTIVES: The purpose of this study was to evaluate the experience of a multidisciplinary team in the percutaneous treatment of thoracic aorta disease. PATIENTS AND METHOD: Between December 2001 and January 2004, 15 patients were selected for percutaneous treatment at the Thoracic Aorta Unit of the Hospital Universitario Central de Asturias. The motives for stent implantation were: degenerative aneurysm (n=7), acute dissection (n=4), penetrating atherosclerotic ulcer (n=1), posttraumatic aneurysm (n=2) and postsurgery pseudoaneurysm (n=1). Four procedures were considered emergencies. Another two patients underwent prior surgery of the supra-aortic branches. Previous computed tomographic angiography and arteriography were performed, and in complex cases of dissection, magnetic resonance imaging was used. All stent placement procedures were performed in the hemodynamics laboratory. All patients underwent computed tomographic angiography during follow-up. RESULTS: Stent positioning was technically successful in 14 patients. The mean length of aortic coverage was 230 +/- 110 mm (range 110-440 mm). No intraoperative deaths occurred. There was one in-hospital death. Transient postimplantation syndrome was presented in three patients. Two type I endoleaks, one type II endoleak and one thrombosis of the superior mesenteric artery were found on computed tomographic angiography at one month. One type III endoleak and one type II endoleak were found during subsequent follow-up. CONCLUSIONS: Endovascular stent-grafting is a valid alternative in the treatment of aortic disease in high-risk patients. Coordination between different medical specialties and appropriate selection of patients are needed. Long-term follow-up is necessary to ensure the usefulness and efficacy of the procedure.     

Three-dimensional ultrasonography: new prospects for ultrasound imaging of bone

Radiography is used for the initial evaluation of suspected bone lesions. We have shown that surface images of bone can be obtained by three-dimensional ultrasonography.     

Flow in the thoracic aorta

Pulsed ultrasonic Doppler velocimetry and theoretical flow analysis have been combined to improve the knowledge and understanding of aortic velocity profiles and wall shear. From the theoretical point of view, particular aspects of the flow were developed, concerning the vorticity in the aorta, the interior velocity distribution, the boundary layer, the flow after separation and the effects of the branches. The experimental approach was performed on dogs, using pulsed ultrasonic Doppler velocimeter providing real-time acquisition of the instantaneous velocity distribution along vascular diameters and perivascular probes designed for bidimensional measurement of velocity distribution. The good agreement found between theory and the experimental velocity profiles has led to comparison of the assessments of axial shear. The peak of the measured shear agrees well with the calculated one; the largest observed shear, obtained at the level of the initial part of the descending thoracic aorta, varies from 4.5 Pa to 7.5 Pa depending on the cardiac output. Finally initial attempts have been made to correlate atheromatous wall lesion localisation with the flow and shear variation.     

MRI of the thoracic aorta

Diseases of the thoracic aorta cause significant morbidity and mortality and can result in potentially catastrophic consequences. Conventional digital subtraction angiography (DSA) has been the gold standard for imaging for many years; however, this is associated with adverse effects and provides only limited information about vessel morphology. DSA is used primarily as a first-line investigation in the setting of trauma. Several other techniques also have been used in recent years, including CT and MRI. This article focuses primarily on the latter.     

Assessment of aortic regurgitation severity by magnetic resonance imaging of the thoracic aorta

A new method of assessing the severity of aortic regurgitationseverity by magnetic resonance imaging has been developed. Twogroups were studied: 20 controls (age=58 ± 19 years)without valvular aortic disease, and 24 patients (age=62 ±13 years) with chronic aortic insufficiency evaluated by magneticresonance and aortic root cineangiography within 1 week of eachother. A magnetic resonance sequence (TR=35 mslTE=12 mslflipangle=20°/magnet=1.5 T) was acquired in a plane containingthe thoracic aorta. A transverse saturation band 30 mm widewas positioned 30–40 mm above the aortic valve. Aorticinsufficiency was graded, the importance of end-diastolic retrogrademovement in the saturation band in the descending aorta wasnoted. Magnetic resonance was also compared to Doppler echocardiographyin 20 patients. In the controls, we found that retrograde blood flow was absent(18/20) or mild (2/20). In contrast, the presence of markedretrograde movement in a saturation band across the thoracicaorta was always associated with severe aortic regurgitation(angiographic grade III or IV). This rapid method (imaging time less than 20 min) can be appliedin most patients with aortic regurgitation and is likely tobe helpful when echocardiography is not possible or gives inconclusiveresults.