[Expansion of indications for total replacement of thoracoabdominal aorta]

Experience of surgical treatment of 111 patients with thoracoabdominal aorta aneurysm are presented in the article. All patients were operated in terms 2007 to December 2011 in the department of aortic surgery of acad. B.V. Petrovskogo RSCS of RAMS. All patients were divided into 3 groups. Thoracoabdominal aorta prosthetics from isthmus to bifurcation was performed in 10 patients of the first group. It was done descending thoracic aorta prosthetics in the second group (72 patients). The third group (29 patients) had suprarenal aorta prosthetics. The groups were comparable with respect to initial severity of underlying and concomitant diseases. Hemorrhage was 6242±3040, 2666±1590 and 2962±1547 ml respectively. Liver and renal failure developed in 10, 7 and 24% of cases respectively (p<0.05). Respiratory failure developed in 40, 33 and 27.6% of cases. Mortality was 10, 7 and 13.8% respectively. It was concluded about comparable treatment outcomes regardless of the amount of reconstruction. It is necessary to develop the techniques improving surgical treatment results and decreasing postoperative complications frequency.

Hybrid technology in treatment of severe combined pathology

The present report describes a clinical case concerning a two-stage hybrid operative intervention in a patient presenting with an aortic arch aneurysm associated with coronary artery disease. The first stage consisted in performing mammary coronary artery bypass grafting of the anterior descending artery, coronary artery bypass grafting of the right coronary artery, endoventricular plasty of the left ventricle according to the Dor technique, switching over of the brachiocephalic arteries to the ascending portion of the aorta with the vascular multiple-branch prosthesis Intergard. The second stage consisted in endoprosthetics of the aortic arch with a stent graft. The patient concerned belongs to a high-risk group for the development of postoperative complications. Endovascular techniques in the pathology involved may be an alternative to the conventional surgical treatment, since there is no necessity to use extracorporeal haemocirculation or deep hypothermal circulatory arrest. It is necessary to analyse the remote results, to work out the indications for the interventions concerned, especially in elderly and aged patients presenting with a variety of accompanying pathology.

[Retrograde type A aortic dissection after endovascular repair of the thoracic artery]

Retrograde type A aortic dissection is a severe and prognostically unfavourable complication of endovascular repair of the thoracic aorta. The aim of the present article is to describe a clinical case report concerning a hybrid operative intervention for retrograde type A aortic dissection in a patient having endured two-stage endovascular repair of the thoracic artery.

[Immediate results of surgical reconstruction of the aortic arch in patients with proximal aortic dissection]

AIM

Despite obvious progress of surgical technologies in correction of proximal aortic pathology, improvement of methods of protection of the brain, one of the main problems of this direction remains the development of postoperative cerebral ischaemia of various degree of manifestation: strokes, transitory ischaemic attacks, or hypoxic encephalopathy. Of special interest is studying the group of patients presenting with aortic dissection, since this pathology may be accompanied by a wide variety of combinations of occlusive and stenotic lesions of the branches of the ascending portion of the aorta and aortic arch (coronary and brachiocephalic basins) by the detached intima.

MATERIAL AND METHODS

Over the period from 1999 to 2011, we operated on a total of 124 patients presenting with DeBakey type I aortic dissection. Of these, 194 were men (75.8%) and 30 (24.2%) women. The mean age amounted to 48.7±11.0 years. Etiologically prevailing were systemic atherosclerosis (91 patients, 73.4% of cases) and Marfan's syndrome in 14 (11.3%) cases. In all patients operative intervention included reconstruction of the aortic arch according to one of the following techniques: prosthetic repair according to the type of an aggressive oblique anastomosis ("hemiarch repair") - 78 (62.9%) patients, prosthetic repair of the aortic arch using the multiple-branch prosthesis Plexus Vascutek - 37 (29.8%) patients, and nine patients underwent prosthetic repair of the aortic arch with a vascular graft with reimplantation of the brachiocephalic arteries with a single islet. The average duration of artificial circulation amounted to 230.1±70.0 minutes, the mean time of aortic occlusion was 167.2±44.2 minutes and that of circulatory arrest equalled 51.9±16.2 minutes. The brain during hypothermic circulatory arrest was protected according to the following techniques: 16 (12.9%) patients - isolated hypothermia with no cerebral perfusion, 76 (61.3 %) patients retrograde cerebral perfusion (RCP) through the superior vena cava, 23 (18.6%) patients - antegrade cerebral perfusion (ACP) and in 8 (6.5%) patients a combination of RCP + antegrade cerebral perfusion.

CONCLUSION

The early postoperative period showed a clear-cut interrelationship between the aetiology of aortic dissection and the onset of impairment of cerebral circulation. Increased incidence of strokes is promoted by more complicated and hence longer in time types of reconstruction of the aortic arch (islet technique, multiple-branch prosthesis). Antegrade cerebral perfusion had no statistically significant advantages over retrograde perfusion or perfusion-free hypothermic protection of the brain. Neither did the type of aortic dissection exert influence on cerebral circulation impairment (CCI). The presence of accompanying diseases did not determine the probability of the development of CCI in the early postoperative period. The analysis of the obtained findings revealed statistically significant relationship between the patient's age and severity of CCI.

[Hybrid technology in repeat operation of a patient with aortic arch aneurysm and type A chronic aortic dissection]

Presented herein is a clinical case report concerning successive use of hybrid technology in secondary surgical treatment of a patient with a progressing aortic arch aneurysm and aortic insufficiency, type A chronic aortic dissection after the primary operation of plasty of the aortic valve with prosthetic repair of the ascending aortic portion for type A acute dissection. The patient underwent hybrid operation: prosthetic repair of the aortic valve with mechanical prosthesis "Carbomedics", prosthetic repair of brachiocephalic branches by means of synthetic prostheses "Vascutek" with their switching to the prosthesis of the ascending aorta, stenting of the arch and descending portion of the aorta. The duration of the postoperative hospital stay amounted to 15 days. The control multispiral computed tomography with intravenous contrasting showed that the reconstruction zone was with no deformities, with the stent graft expanded, and no leaks noted. The conclusion was made that further improvement of hybrid technique can make it a true alternative to classical surgical operations in this severely ill cohort of patients. The presented clinical example demonstrates that simultaneous hybrid surgical intervention is the most correct approach in the given situation decreasing lowering the risk of the development of complications in both immediate and remote postoperative period.

[Mega aorta: Borst operation or Kouchoukos operation?]

It was done 163 operations on aortic arch in terms 2000 to December 2011. All patients were operated in the department of aortic surgery of acad. B.V. Petrovskogo RSCS of RAMS. 36 operations were performed by using of Borst's technique and 9 operations - by using of Kouchoukos technique in case of extended aneurysms of thoracic aorta. All patients did not differ in the severity of primary state, concomitant diseases and age. Duration of cardiopulmonary bypass and internal organs ischemia were 189±55/190±47 and 55±8/77±20 min respectively. Complication frequency was 27% and 22% in case of cardiovascular failure. Respiratory failure was 16.7% and 33%. Liver and renal failure was observed in 27% and 11% of cases. Encephalopathy was detected 33% and 22% of cases. Mortality was 22% and 11% of cases. It was concluded that Kouchoukos technique is alternative and safe method in thoracic aorta aneurysm treatment.

[Remote results of surgical reconstruction of the aortic arch in patients with proximal aortic dissection]

INTRODUCTION

It is generally known that Stanford type A aortic dissection has up to now been a serious problem of cardiothoracic surgery. The current state of the art of aortic surgery, anaesthesiological support, and perfusion strategy make it possible to achieve acceptable results in the early postoperative period in various-difficulty aortic arch reconstruction. Taking into consideration that the pathological process to some extent involves the brachiocephalic arteries, of special interest are remote results of various in aggressiveness and radicality types of reconstruction of the aortic arch in its proximal dissection from the point of view of the development of delayed impairments of cerebral circulation.

MATERIAL AND METHODS

Over the period from 1999 to 2011, specialists of the Novosibirsk Scientific Research Institute for Circulatory Pathology named after Academician E.N. Meshalkin under the Ministry of Public Health and Social Development operated on a total of 124 patients presenting with DeBakey type I aortic dissection. All factors supposedly influencing the development of cerebral ischaemia were subdivided into the qualitative and quantitative ones. The qualitative factors included gender, aetiology, type of dissection, type of aortic arch reconstruction, type of cerebral perfusion, type of intervention on the aortic root, previous operations on the heart, and the presence of accompanying CAD, arterial hypertension, chronic obstructive pulmonary diseases, and renal pathology. The quantitative factors were as follows: age, height, body weight, duration of assisted circulation (AC), duration of aortic occlusion (AO), duration of circulatory arrest (CA). We examined a total of 80 patients within the terms of 11-124 months (mean 48,3±26,0 months) after surgical treatment. We studied interrelationship between the factors and the development of cerebral circulation impairments in the remote postoperative period.

CONCLUSION

In the remote postoperative period virtually all cases of focal impairments of cerebral circulation were associated with accompanying atherosclerosis, i. e. the already compromised brachiocephalic vascular bed. Amongst the qualitative parameters the most significant variables were: aetiology, accompanying diseases, and the type of cerebral perfusion.

Multifactorial relationship between 18F-fluoro-deoxy-glucose positron emission tomography signaling and biomechanical properties in unruptured aortic aneurysms

BACKGROUND

The relationship between biomechanical properties and biological activities in aortic aneurysms was investigated with finite element simulations and 18F-fluoro-deoxy-glucose (18F-FDG) positron emission tomography.

METHODS AND RESULTS

The study included 53 patients (45 men) with aortic aneurysms, 47 infrarenal (abdominal aortic) and 6 thoracic (thoracic aortic), who had ≥1 18F-FDG positron emission tomography/computed tomography. During a 30-month period, more clinical events occurred in patients with increased 18F-FDG uptake on their last examination than in those without (5 of 18 [28%] versus 2 of 35 [6%]; P=0.03). Wall stress and stress/strength index computed by finite element simulations and 18F-FDG uptake were evaluated in a total of 68 examinations. Twenty-five (38%) examinations demonstrated ≥1 aneurysm wall area of increased 18F-FDG uptake. The mean number of these areas per examination was 1.6 (18 of 11) in thoracic aortic aneurysms versus 0.25 (14 of 57) in abdominal aortic aneurysms, whereas the mean number of increased uptake areas colocalizing with highest wall stress and stress/strength index areas was 0.55 (6 of 11) and 0.02 (1 of 57), respectively. Quantitatively, 18F-FDG positron emission tomographic uptake correlated positively with both wall stress and stress/strength index (P<0.05). 18F-FDG uptake was particularly high in subjects with personal history of angina pectoris and familial aneurysm.

CONCLUSIONS

Increased 18F-FDG positron emission tomographic uptake in aortic aneurysms is strongly related to aneurysm location, wall stress as derived by finite element simulations, and patient risk factors such as acquired and inherited susceptibilities.

Emergency endovascular stent-grafting for acute type B aortic dissection with symptomatic malperfusion

AIM

The aim of this paper was to analyze the durability and efficacy of emergency thoracic endovascular aortic repair (TEVAR) for acute Stanford type B aortic dissection (TBAD) with malperfusion syndrome.

METHODS

A retrospective analysis of acute TBAD with spinal cord, kidney, viscera, and extremity malperfusion was performed. Emergency TEVAR to cover primary tear site by stent-graft was strongly suggested to included candidates. Computed tomography (CT) scans and clinical findings were carried out in diagnosis and follow-up.

RESULTS

One hundred twenty-seven TBAD patients (101 men, 46.1±11.4 year, range 34~76) who presented with acute end-organ malperfusion, including sudden paraplegia (N.=4), acute renal failure (N.=26), acute viscera ischemia (N.=61) and limb ischemia (N.=36), received aortic stent-grafting 2~48 hours after onset. Technical success was achieved in all primary TEVAR. The overall endoleak rate was 7.1% (9/127; typeI:3; typeII: 4; typeIV: 2). The 30-day mortality was 0.8% (2/127). 125 patients were followed for 19.1±14.5 (1~86) months, one patient died 50 days post-TEVAR due to myocardial infarction. Four patients required reintervention with additional stent grafts. Follow-up CT angiography showed enlargement of the true lumen and different degrees of thrombosis in the distal false lumen (complete thrombosis in 48, partial thrombosis in 52 and patency in 24).

CONCLUSION

Emergency TEVAR is an effective method to treat acute TBAD complicated with end-organ malperfusion. Covering of the proximal entry site of TBAD by stent-graft leads to flow increased in the true lumen and thrombosis of the false lumen of varying degree, which may improve end-organ perfusion and restore branch vessels patency.

Molecular mechanisms of thoracic aortic dissection

Thoracic aortic dissection (TAD) is a highly lethal vascular disease. In many patients with TAD, the aorta progressively dilates and ultimately ruptures. Dissection formation, progression, and rupture cannot be reliably prevented pharmacologically because the molecular mechanisms of aortic wall degeneration are poorly understood. The key histopathologic feature of TAD is medial degeneration, a process characterized by smooth muscle cell depletion and extracellular matrix degradation. These structural changes have a profound impact on the functional properties of the aortic wall and can result from excessive protease-mediated destruction of the extracellular matrix, altered signaling pathways, and altered gene expression. Review of the literature reveals differences in the processes that lead to ascending versus descending and sporadic versus hereditary TAD. These differences add to the complexity of this disease. Although tremendous progress has been made in diagnosing and treating TAD, a better understanding of the molecular, cellular, and genetic mechanisms that cause this disease is necessary to developing more effective preventative and therapeutic treatment strategies.

Differential tensile strength and collagen composition in ascending aortic aneurysms by aortic valve phenotype

BACKGROUND

Ascending thoracic aortic aneurysm (ATAA) predisposes patients to aortic dissection and has been associated with diminished tensile strength and disruption of collagen. Ascending thoracic aortic aneurysms arising in patients with bicuspid aortic valve (BAV) develop earlier than in those with tricuspid aortic valves (TAV) and have a different risk of dissection. The purpose of this study was to compare aortic wall tensile strength between BAV and TAV ATAAs and determine whether the collagen content of the ATAA wall is associated with tensile strength and valve phenotype.

METHODS

Longitudinally and circumferentially oriented strips of ATAA tissue obtained during elective surgery were stretched to failure, and collagen content was estimated by hydroxyproline assay. Experimental stress-strain data were analyzed for failure strength and elastic mechanical variables: α, β, and maximal tangential stiffness.

RESULTS

The circumferential and longitudinal tensile strengths were higher for BAV ATAAs when compared with TAV ATAAs. The α and β were lower for BAV ATAAs when compared with TAV ATAAs. The maximal tangential stiffness was higher for circumferential when compared with longitudinal orientation in both BAV and TAV ATAAs. The amount of hydroxyproline was equivalent in BAV and TAV ATAA specimens. Although there was a moderate correlation between the collagen content and tensile strength for TAV, this correlation is not present in BAV.

CONCLUSIONS

The increased tensile strength and decreased values of α and β in BAV ATAAs despite uniform collagen content between groups indicate that microstructural changes in collagen contribute to BAV-associated aortopathy.

Extensive endovascular repair of thoracic aorta: observational analysis of the results and effects on spinal cord perfusion

AIM

The study aims to analyze retrospective results of extensive endovascular repair of the descending thoracic aorta with special attention to spinal cord malperfusion.

METHODS

From April 2002 through November 2011, 21 patients underwent stent-graft coverage of the thoracic aorta from the aortic arch at the origin of the left subclavian artery to the celiac trunk, 6 (mean age =72.3±8.1) for aneurysm disease, 13 (mean age =74.3±8.4) for type B aortic dissection and 2 (mean age =52.1±6.5) for aortic rupture. The mean of aortic diameter in cases with aneurysm disease was 7.1±1.6 cm and the causes of aortic rupture were post-traumatic and aneurysm pathology respectively. In all cases needing coverage of the left subclavian artery duplex ultrasonography and flowmetry were performed to evaluate patency and flow of both the vertebral arteries.

RESULTS

Technical success was 100% with 0% in-hospital mortality. The left subclavian artery was crossed with the uncovered portion of the stent-graft in 11 cases (52.4%) and the covered segment in the other 10 patients (47.6%) without subclavian revascularization because no pre-operative hemodynamic alterations of vertebral arteries were revealed by duplex ultrasonography. The incidence of paraplegia was 9.5% in 2 patients who had prior abdominal aortic aneurysm repair: the first case with preoperative type B aortic dissection presented significant lower extremity paresis within 24 hours after the procedure and in the second patient with a large thoracic aneurysm the signs of paraplegia were evident 3 weeks after discharge from Hospital probably due to delayed occlusion of a major medullary artery. The cumulative survival rate after 1, 3 and 9 years was 91%, 81%, and 71%.

CONCLUSIONS

The coverage of the entire thoracic aorta is an effective procedure with high probability of success. Spinal cord malperfusion remains a serious complication especially in patients with prior aortic surgery but if collateral blood supply is maintained the occlusion of intercostal arteries do not determine paraplegia or paraparesis. In order to consider acute or chronic occlusion of subclavian, lumbar or hypogastric arteries so preventing spinal cord ischemia, strong preoperative evaluation including analysis of previous surgery for abdominal aortic aneurysm repair and avoidance of T12 aortic segment coverage if feasible is mandatory.

Educational paper. Connective tissue disorders with vascular involvement: from gene to therapy

Heritable connective tissue diseases comprise a heterogeneous group of multisystemic disorders that are characterized by significant morbidity and mortality. These disorders do not merely result from defects in the amount or structure of one of the components of the extracellular matrix, as the extracellular matrix also serves other functions, including sequestration of cytokines, such as transforming growth factor beta (TGFβ). Indeed, disturbed TGFβ signaling was demonstrated in several heritable connective tissue diseases, including syndromic forms such as Marfan or Loeys-Dietz syndrome and non-syndromic presentations of thoracic aortic aneurysm/dissection. Because of these findings, new therapeutic targets have been unveiled, leading to the initiation of large clinical trials with angiotensin II type 1 receptor antagonists that also have an inhibiting effect on TGFβ signaling. Here, we present an overview of the clinical characteristics, the molecular findings, and the therapeutic strategies for the currently known syndromic and non-syndromic forms of thoracic aortic aneurysm/dissection.

Reproduction of pressure field in ultrasonic-measurement-integrated simulation of blood flow

Ultrasonic-measurement-integrated (UMI) simulation of blood flow is used to analyze the velocity and pressure fields by applying feedback signals of artificial body forces based on differences of Doppler velocities between ultrasonic measurement and numerical simulation. Previous studies have revealed that UMI simulation accurately reproduces the velocity field of a target blood flow, but that the reproducibility of the pressure field is not necessarily satisfactory. In the present study, the reproduction of the pressure field by UMI simulation was investigated. The effect of feedback on the pressure field was first examined by theoretical analysis, and a pressure compensation method was devised. When the divergence of the feedback force vector was not zero, it influenced the pressure field in the UMI simulation while improving the computational accuracy of the velocity field. Hence, the correct pressure was estimated by adding pressure compensation to remove the deteriorating effect of the feedback. A numerical experiment was conducted dealing with the reproduction of a synthetic three-dimensional steady flow in a thoracic aneurysm to validate results of the theoretical analysis and the proposed pressure compensation method. The ability of the UMI simulation to reproduce the pressure field deteriorated with a large feedback gain. However, by properly compensating the effects of the feedback signals on the pressure, the error in the pressure field was reduced, exhibiting improvement of the computational accuracy. It is thus concluded that the UMI simulation with pressure compensation allows for the reproduction of both velocity and pressure fields of blood flow.

Spinal cord function monitoring during endovascular treatment of thoracoabdominal aneurysms: implications for staged procedures

AIM

Spinal cord ischemia is a well-known complication in the treatment of thoracoabdominal aneurysms (TAAA). Despite the fact that endovascular treatment of TAAA is less invasive, spinal cord ischemia rate is not reduced if compared to open repair.

METHODS

We report the results of our experience of spinal cord function monitoring by measuring motor evoked potentials (MEP) during endovascular treatment of TAAA type II and III. Depending on the level of the MEPs the decision is made whether to stage the procedure or not. We treated ten patients according to this protocol.

RESULTS

In two patients, MEPs decreased 50% or more and procedures were staged. Both experienced no neurological complications after first and second procedure. No MEPs decrease was seen during the second procedures. One of the other eight patients had a temporary right lower leg pararesis.

CONCLUSION

In conclusion we state that our first experience demonstrates the value of assessing spinal cord function during extensive endovascular TAAA repair with subsequent strategies to prevent paraplegia.

Intentional left subclavian artery coverage without revascularization during TEVAR

At present, endovascular therapy is a well-established treatment for different types of thoracic aortic pathologies. There is growing evidence, that thoracic endovascular aortic repair (TEVAR) has advantages over open repair with regard to perioperative morbidity and mortality in the treatment of thoracic aortic aneurysms. However, in up to 50% of TEVAR procedures the proximal end of the stent-graft will (partly) cover the origin of the left subclavian artery (LSA) in order to achieve a save sealing zone. Intracranial stroke and paraplegia are feared complications and might be associated with LSA exclusion from the circulation. Unfortunately, no reliable technique is available to assess the individual risk of stroke and paraplegia in case of LSA coverage, so that the indication for LSA revascularization continues to be matter of assuming and guessing. The quality of available evidence on necessity or superfluity to revascularize the LSA is very low and studies report, to some extent, controversial outcome after intentional LSA coverage. In the light of the devastating consequences for patients in case of neurological complications due to LSA coverage the question of prophylactic LSA revascularization remains a significant problem which is elucidated and discussed in this manuscript.

Advanced endovascular techniques for thoracic and abdominal aortic dissections

Endovascular treatment of aortic dissection is still in its infancy and consists usually of implantation of thoracic tubular stent-grafts to cover the proximal entry tear and redirect flow into the true lumen. Large registries comparing endovascular treatment by thoracic endovascular aortic repair (TEVAR) with open surgery for aortic dissection of the descending aorta have demonstrated a clear benefit for endovascular treatment with lower mortality and morbidity rates turning TEVAR into the standard treatment for complicated type B aortic dissection. With this momentum of success endovascular techniques continue to challenge open surgical techniques also in the aortic arch and the ascending aorta. TEVAR for aortic dissection has become more complex requiring an individualized treatment strategy as endovascular techniques have developed with the advent of new devices and increased experience of the operators. In many cases straight implantation of a thoracic tubular stent-graft is sufficient. But as rerouting of the blood flow can also change perfusion of vital side-branches the endovascular operator needs to have a large armamentarium of techniques and adjunctive procedures in order to sufficiently address the individual patient morphology. This chapter reviews a variety of endovascular techniques including access techniques, proximal sealing, the Petticoat-technique, false lumen deployment, fenestration techniques, branch vessel stenting and false lumen obstruction by various techniques.

[Does the volume of the intervention on the aortic arch influences the results of surgical treatment?]

The issue centers on the critical analysis of the results of the aortic arch surgery, performed using the two basic methods: hemiarch and total arch replacement. 130 patients were included in the study. All were operated on in conditions of moderate hypothermia and antegrade brain perfusion. The study demonstrates that the volume of the intervention does not influence the results. The main success criteria is the adequacy of the brain and internal organs perfusion.

[Functional properties of smooth muscle cells in ascending aortic aneurysm]

Thoracic aortic aneurism (TAA) develops as a result of complex series of events that dynamically alter the structure and composition of the aortic vascular extracellular matrix (ECM). The main elements that alter the composition of aortic wall are smooth muscle cells (SMC). The purpose of the present work was to study alteration of smooth muscle cell functions derived from the patients with TAA and from healthy donors. As it is supposed that TAA associated with bicuspid aortic valve (BAV) and with tricuspid aortic valve (TAV) differ in their pathogenesis, we compared the SMC and tissues samples from BAV-, TAV-patients and healthy donors. We compared TAA patients' derived tissues and SMC to healthy donors' ones in several parameters: SMC growth, migration and apoptotic dynamics; metalloproteinase MMP2 and MMP9 activity (zymography) and elastin, collagen and fibrillin content (Western blot) in both tissue samples and cultured SMC. Proliferation ability of both BAV and TAV SMC was decreased comparing to donors cells; migration ability in scratch tests was increased in TAV-derived SMC comparing to donor cells. BAV-cells migration ability was not changed comparing to donor-SMC. Elastin content was decreased in TAA SMC comparing to donor cells whereas the content of fibrillin and collagen was not altered. At the same time elastin and collagen protein level was significantly higher in tissue samples of TAA patients comparing to donor-derived samples. SMS proliferation and migration ability is differently affected in TAV and BAV-associated TAA that supports the idea of different nature of these two groups of TAA. Also our data show that SMC functional properties are altered in TAA patients and these alterations could play a significant role in the disease pathogenesis.

[Hybrid operation for a posttraumatic saccular aneurysm of the aortic arch]

The article deals with a case report of successful hybrid surgical treatment of a patient presenting with a posttraumatic large false saccular aneurysm of the aortic arch with mediastinal displacement and compression of the left recurrent laryngeal nerve and trachea. The patient was subjected to a hybrid operation, i. e., bypass grafting of the brachiocephalic trunk and the left common carotid artery with a bifurcation prosthesis from the ascending aorta through sternotomy, carotid-vertebral and carotid-subclavian bypass grafting on the left in a combination with endoprosthetic repair of the aortic arch with the stent graft Valiant Thoracic 40 × 224 mm (VAMF 4040c200TE) manufactured by the Medtronic Company. The postoperative period was uneventful followed by rather rapid rehabilitation of the patient. One month after the operation, the clinical state improved considerably. His voice restored virtually completely, and breathlessness disappeared. According to the findings of MSCT angiography, the aneurysmatic cavity is thrombosed, with the stent graft showing no evidence of either dislocation or endoleak. The bifurcation bypass graft is functioning. According to the data of duplex scanning, the anastomoses established on the neck are patent.

Evaluation of 3D blood flow patterns and wall shear stress in the normal and dilated thoracic aorta using flow-sensitive 4D CMR

BACKGROUND

The purpose of this study was to investigate 3D flow patterns and vessel wall parameters in patients with dilated ascending aorta, age-matched subjects, and healthy volunteers.

METHODS

Thoracic time-resolved 3D phase contrast CMR with 3-directional velocity encoding was applied to 33 patients with dilated ascending aorta (diameter≥40 mm, age=60±16 years), 15 age-matched normal controls (diameter≤37 mm, age=68±7.5 years) and 15 young healthy volunteers (diameter≤30 mm, age=23±2 years). 3D blood flow was visualized and flow patterns were graded regarding presence of supra-physiologic-helix and vortex flow using a semi-quantitative 3-point grading scale. Blood flow velocities, regional wall shear stress (WSS), and oscillatory shear index (OSI) were quantified.

RESULTS

Incidence and strength of supra-physiologic-helix and vortex flow in the ascending aorta (AAo) was significantly higher in patients with dilated AAo (16/33 and 31/33, grade 0.9±1.0 and 1.5±0.6) than in controls (2/15 and 7/15, grade 0.2±0.6 and 0.6±0.7, P<.05) or healthy volunteers (1/15 and 0/15, grade 0.1±0.3 P<.05). Greater strength of the ascending aortic helix and vortex flow were associated with significant differences in AAo diameters (P<.05). Peak systolic WSS in the ascending aorta and aortic arch was significantly lower in patients with dilated AAo (P<.0157-.0488). AAo diameter positively correlated to time to peak systolic velocities (r=0.30-0.53, P<.04), OSI (r=0.33-0.49, P<0.02) and inversely correlated to peak systolic WSS (r=0.32-0.40, P<.03). Peak systolic WSS was significantly lower in AAo aneurysms at the right and outer curvature within the AAo and proximal arch (P<.01-.05).

CONCLUSIONS

Increase in AAo diameter is significantly correlated with the presence and strength of supra-physiologic-helix and vortex formation in the AAo, as well with decrease in systolic WSS and increase in OSI.