Yale milestones in reading the playbook of thoracic aortic aneurysms

This paper reviews the major milestones in the understanding and treatment of thoracic aortic disease from the clinical and investigative team at Yale University.

Emergent repair of a complex dissecting aneurysm in the thoracic aorta

Endovascular treatment of complex thoracic pathologic conditions involving the aortic arch can often be appropriate and safe; however, minimally invasive procedures are not always feasible, especially in emergent cases. We report the case of a 78-year-old woman who emergently presented in hemorrhagic shock with a ruptured chronic dissecting aneurysm that involved the aortic arch. Eight years earlier, she had undergone aortic valve replacement and plication of the ascending aorta, which was complicated a day later by Stanford type B dissection, malperfusion, and ischemia that required an axillobifemoral bypass. At the current admission, we successfully treated her surgically through a left thoracotomy, using moderate hypothermic extracorporeal circulation and advanced organ-protection methods. We discuss the surgical indications and our operative strategy in relation to open surgical repair versus endovascular treatment in patients with complex conditions.

[First experience with monitoring somatosensory and motor evoked potential during operations on the thoracic and thoracoabdominal portions of the aorta]

Specialists in Russia have recently gained vast experience in operations on the thoracic and thoracoabdominal portion of the aorta; however, studying evoked potentials for preventing lesions of the spinal marrow have not been studied in any clinic. The authors report herein their first experience in Russia in studying the function of the marrow during operations on the aorta followed by detailed description of the technique of registering evoked potentials. From June 2010 to January 2011, specialists of the Arterial Pathology Department of the A. N. Bakulev Scientific Centre for Cardiovascular Surgery under the Russian Academy of Medical Sciences carried out a neurophysiological study in a total of 19 patients during operations for thoracic and thoracoabdominal aortic aneurysms. The somatosensory and motor evoked potentials were studied using an 8-channel neuroenhancer Keypoint (Dantec, Denmark). The hospital mortality rate in the examined group amounted to 5.2% (1/19). Spinal stroke developed in 2 patients, i.e. in 10.5% (2/19). The alterations in the somatosensory and motor evoked potentials were subdivided into groups according to the morphological classification of Crawford-Cunningham. A further two patients were found to have during operation type III changes in the evoked potentials, with both having developed postoperative spinal stroke. Thus, the method of intraoperative monitoring of evoked potentials has high sensitivity and specificity and can be included into the protocol of operations on the thoracic and abdominothoracic portion of the aorta. During monitoring of evoked potentials it is necessary to maintain a permanent level of anaesthesia and myorelaxation with obligatory participation of the neurophysiologist in the operation.

[Treatment of a patient with a ruptured infectious aneurysm of the aortic arch]

Described in the article is a clinical case report concerning surgical treatment of a 65-year-old male patient presenting with a ruptured infectious aortic arch aneurysm. He was subjected to an operation consisting in prosthetic repair of the ascending portion of the aorta and aortic arch with a homograft under conditions of artificial circulation, deep hypothermia, and antegrade cerebral perfusion.

[A rare case of surgical management of a patient with thoracic aortic aneurysm]

Described in the article is a clinical case of successful surgical management of a male patient diagnosed with a syphilitic-origin aneurysm of the thoracic aorta isthmus, complicated by an aortopulmonary fistula. Also presented herein are the clinical pattern, findings of examination, and treatment policy. This is followed by a detailed description of both the course of the surgical intervention and outcomes obtained.

[Single-step surgical management of lesions of the ascending aorta and aortic arch, coronary and carotid arteries in a male patient with multifocal atherosclerosis]

Described in the article is a clinical case report concerning single-step surgical management of a male patient presenting with multifocal atherosclerosis accompanied by an aneurysm of the ascending aorta and proximal segment of the aortic arch combined with lesions of the coronary and brachiocephalic vessels, thus showing a possibility of surgical treatment in this cohort of patients, if completely and timely diagnosed. Performing a one-stage operation without aggravating the surgical intervention makes it possible to decrease the risk of complications of both the heart and brain in the intra- and postoperative periods.

Changes of motor evoked potentials during descending thoracic and thoracoabdominal aortic surgery with deep hypothermic circulatory arrest

BACKGROUND

Paraplegia is a serious complication of descending and thoracoabdominal aortic aneurysms (dTAAs and TAAAs) surgery. Motor evoked potentials (MEPs) enable monitoring the functional integrity of motor pathways during dTAA and TAAA surgery. Although MEPs are sensitive to temperature changes, there are few human data on changes of MEPs during mild and deep hypothermia. Therefore, we investigated changes of MEPs in deep hypothermic circulatory arrest (DHCA) in dTAA and TAAA surgery.

METHODS

Fifteen consecutive patients undergoing dTAA and TAAA surgery using DHCA were enrolled. MEPs were elicited and recorded during each degree Celsius change in nasopharyngeal temperature during both the cooling and rewarming phases. Hand and leg skin temperature were also recorded simultaneously.

RESULTS

In the cooling phase MEP amplitude decreased lineally in both the hand and leg. The MEP disappeared at ~16°C in both the hand and leg in 10 of 15 patients, but was still elicited in 5 patients. In the rewarming phase MEP in the hand recovered before the temperature reached 20°C for eight patients and 25°C for the other seven patients. In contrast, MEP in the leg recovered below 20°C for two patients and 30°C for three patients. For the other eight patients MEP waves did not recover during the rewarming phase.

CONCLUSION

In the cooling phase of DHCA, MEP disappeared at ~16°C in some patients but was still elicited in others. MEP recovered below 25°C in the hand. Recovery of MEP in the leg was, however, extremely variable.

Acute thoracic aortic syndromes

Patients presenting with acute thoracic aortic syndromes require immediate evaluation and stabilization. Although emergent surgical intervention may not be warranted in all cases, managing clinicians should be cognizant of the fact that these diseases are dynamic and that they can rapidly degenerate yielding catastrophic consequences. While traditional surgical intervention has failed to reduce mortality rates in those requiring emergent intervention for descending thoracic aortic syndromes, evolving endovascular techniques hold promise and may prove to extend benefits beyond that which are currently generated with open graft aortic replacement.

[Hemodynamic study of thoracic aortic aneurysm based on computational fluid dynamics technique]

OBJECTIVE

To establish a patient-specific hemodynamics model of thoracic aortic aneurysm (TAA) based on computational fluid dynamics technique and investigate its role in the study of growth and rupture mechanism of TAA.

METHODS

3D realistic model of thoracic aortic aneurysm was reconstructed from DICOM format computed tomography angiography (CTA) images of a male patient. The geometry was reconstructed using medical image processing software Mimics. The blood flow in aorta was assumed to be laminar and incompressible and the blood Newtonian fluid. A time-dependent pulsatile boundary condition was deployed at inlet. Unsteady blood flow simulation was performed in real geometry of TAA with a finite volume method (FVM) code FLUENT. The hemodynamic parameters related with the growth and rupture of aneurysm were analyzed.

RESULTS

Analysis of the distributions of hemodynamic variables during the cardiac cycle such as wall shear stress, streamlines and velocity profiles in TAA were carried out. The numerical simulation results demonstrated that the blood velocity of proximal neck was considerably faster than that of aneurysm body. The outer wall of proximal aneurysm body was hit by blood jet entering aneurysm. Instant streamlines at peak systole showed that the entering blood stream hit the aneurysm wall and right-hand helical vortex was observed in aneurysm body. The distributions of high wall shear stress were observed in the proximal and distal aneurysm neck and the area where the entering blood stream first hit the wall. Large regions of lower wall shear stress occurred in aneurysm body.

CONCLUSION

The growth and rupture mechanisms of TAA may be analyzed based on a constructed patient-specific model and hemodynamic simulation.

Results of proximal arch replacement using deep hypothermia for circulatory arrest: is moderate hypothermia really justifiable?

The use of selective cerebral perfusion with warmer temperatures during circulatory arrest has been increasingly used for arch replacement over concerns regarding the safety of deep hypothermic circulatory arrest (DHCA). However, little data actually exist on outcomes after arch replacement and DHCA. This study examines modern results with DHCA for proximal arch replacement to provide a benchmark for comparison against outcomes with lesser degrees of hypothermia. Between July 2005 and June 2010, 245 proximal arch replacements ("hemiarch") were performed using deep hypothermia; mean minimum core and nasopharyngeal temperatures were 18.0 ± 2.1°C and 14.1 ± 1.6°C, respectively. Adjunctive cerebral perfusion was used in all cases. Concomitant ascending aortic replacement was performed in 41 per cent, ascending plus aortic valve replacement in 23 per cent, and aortic root replacement in 32 per cent. Mean age was 58 ± 14 years; 36 per cent procedures were urgent/emergent. Mean duration of DHCA was 20.4 ± 6.2 minutes. Thirty-day/in-hospital mortality was 2.9 per cent. Rates of stroke, renal failure, and respiratory failure were 4.1 per cent (0.8% for elective cases), 1.2 per cent, and 0.4 per cent, respectively. Deep hypothermia with adjunctive cerebral perfusion for circulatory arrest during proximal arch replacement affords excellent neurologic as well as nonneurologic outcomes. Centers using lesser degrees of hypothermia for arch surgery, the safety of which remains unproven, should ensure comparable results.

Cost associated with D-Dimer screening for acute aortic dissection

INTRODUCTION

D-Dimer (DD) has been described as a useful predictor of both morphologic changes in acute thoracic aortic dissection (TAD) and of TAD-associated mortality. This study analyzed the use of DD screening to screen patients with chest pain for acute (TAD) to determine if it improves diagnosis and cost effectiveness. This study also looked at the association of DD levels with diagnoses frequently seen in patients with dyspnea or chest pain.

METHODS

At the Helios Hospital, Krefeld, the authors analyzed the data of all patients (n = 1053, age (mean, SD) 62 ± 19 years, 49% males) admitted for chest pain to the nonsurgical emergency department (ED) in February 2010. Chest pain was the second most frequent symptom causing 138 (13.1%) admissions, 102 of which had DD testing (Inniovance® D-Dimer Assay, Dade Behring/Siemens, Germany). To assess the diagnostic reliability of DD testing, the sensitivity, specificity, and odds ratio, including 95% confidence interval, were estimated.

RESULTS

None of the patients admitted were found to have acute TAD. Had the authors used a computerized tomography (CT) scan to rule out TAD in every patient with chest pain, actual costs would have been euro 12,328. A restriction of CT scans to patients with elevated DD levels would have lowered costs to euro 5360. The actual costs were euro 670.30 for CT scans and euro 540.60 for DD tests. On analyzing the association with other diagnoses, both sensitivity and specificity were low, with the exception of pneumonia.

CONCLUSION

Owing to the low incidence of TAD, DD screening increases diagnostic efforts and costs but it remains unclear whether it would actually speed up TAD diagnosis. In a clinical setting DD did not help to discriminate other relevant diagnoses. Despite the high sensitivity of DD for aortic dissection published in the literature, the physician's clinical judgment remains paramount.

Management of acute type B aortic dissections and acute limb ischemia

The aim of this study was to review the management of acute type B aortic dissection (TBAD) with acute limb ischemia. A search using the "Pubmed" resulted in 254 records by combining the Medical Subject Heading keywords (listed separately). The articles were assessed for their validity, correct pathology and patient cohort. Inclusion criteria included all patients with complicated acute TBAD who were candidates for open of thoracic endovascular aortic repair (TEVAR). The exclusion criteria included type A, asymptomatic acute or chronic TBAD, penetrating ulcer or intramural hematoma. TBAD with limb ischemia has a poor prognosis if not diagnosed, triaged and treated promptly. Clinical presentation and diagnostic strategy as well as various imaging are reviewed. Early mortality rate for complicated acute TBAD (with malperfusion to lower extremity) is 12%. The management has moved from open operation to primary TEVAR. In cases with anatomic obstruction, open surgical techniques such as femoral-femoral bypass, axillo-femoral bypass or surgical fenestration can be successful in relief of malperfusion to the affected limb. One-year-survival rates are 85%. A complete to partial reverse aortic remodeling occurred in 78% of survivors of acute TBAD, if primary TEVAR is applied. Acute TBAD with limb ischemia remains a clinical challenge that requires prompt diagnosis and treatment. TEVAR of acute TBAD is associated with relatively low morbidity and mortality, and is more often used as primary approach for patients with limb ischemia. The outcomes with TEVAR compare favorably to the open repair, and initiate reverse aortic remodeling in majority of the survivors.

Impact of aortic repair based on flow field computer simulation within the thoracic aorta

Purpose of this computational study is to examine the hemodynamic parameters of velocity fields and shear stress in the thoracic aorta with and without aneurysm, based on an individual patient case and virtual surgical intervention. These two cases, case I (with aneurysm) and II (without aneurysm), are analyzed by computational fluid dynamics. The 3D Navier-Stokes equations and the continuity equation are solved with an unsteady stabilized finite element method. The vascular geometries are reconstructed based on computed tomography angiography images to generate a patient-specific 3D finite element mesh. The input data for the flow waveforms are derived from MR phase contrast flow measurements of a patient before surgical intervention. The computed results show velocity profiles skewed towards the inner aortic wall for both cases in the ascending aorta and in the aortic arch, while in the descending aorta these velocity profiles are skewed towards the outer aortic wall. Computed streamlines indicate that flow separation occurs at the proximal edge of the aneurysm, i.e. computed flow enters the aneurysm in the distal region, and that there is essentially a single, slowly rotating, vortex within the aneurysm during most of the systole. In summary, after virtual surgical intervention in case II higher shear stress distribution along the descending aorta could be found, which may produce more healthy reactions in the endothelium and benefit of vascular reconstruction of an aortic aneurysm at this particular location.

[Surgical treatment of the aortic dissection type B: analysis of 15 years' experience]

65 patients with the aortic dissection type B were operated on in the period 1995-2010. The proximal local aortic prosthetics proved to be the method of choice in treatment of such patients. The method allowed the reduction of the hospital lethality on 5,7 ± 3,9% and considerably decrease the overall hospital stay.

[Hybrid surgical management of a saccular aneurysm of the aortic arch]

The present article aims to describe a clinical case of hybrid surgical intervention consisting in complete prosthetic repair of the aortic arch in a high-risk male patient diagnosed with a gigantic saccular aneurysm of the aortic arch. The patient was subjected to a hybrid operation--an operation of endovascular prosthetic repair of the thoracic portion of the aorta with the Gore Tag stent graft in a combination with bypass grafting of the left common carotid and left subclavian arteries with the Gore bifurcated stent graft, autovenous aortocoronary bypass grafting of the CA without artificial circulation. The postoperative period was uneventful with the patient's favourable convalescence and rehabilitation occurring within the shortest terms possible. According to the findings of MSCT-aortography, fulfilment of the arteries of the aortic arch with contrast medium was satisfactory. The residual cavity of the aneurysm was completely isolated from the blood flow, with no endoleak. The arteries of the aortic arch were opacified through the bifurcation prosthesis from the ascending portion of the aorta. Hybrid surgical interventions appear to possess all positive properties of endovascular (according to the findings of the EVAR1 and EVAR2 Trials) and traditional open surgery, thus allowing of both avoiding threatening complications and minimizing the terms of rehabilitation. This technique might thus be considered a useful tool to be included into the basic armamentarium of the vascular surgeon as an option of revascularization.

[Hybrid reconstructive interventions in distal aortic dissection]

The authors report herein the findings of a prospective study including a total of 26 patients presenting with distal aortic dissection and treated by prosthetic repair of the descending portion of the thoracic aorta. The patients were subdivided into two groups, with Group One comprising 15 patients having the blood flow directed into the true channel and Group Two composed of eleven patients subjected to directing blood flow into the both channels. Twelve (80%) Group One patients were found to have thrombosis of the false channel and an increase in the true channel's diameter. Five (45%) Group Two patients in the remote period developed dilatation of the abdominal aorta requiring distal prosthetic repair in three of them. A further two patients intraoperatively received uncoated stentgrafts (Djumbodies Dissection System, Saint Come Chirurgie, France) inserted into the distal portion of the thoracoabdominal aorta in order to provide adequate perfusion of the visceral branches. It was shown that local prosthetic repair of the descending thoracic aorta is appropriate only in case of the blood flow directed into the true lumen and expansion of the compressed true channel of the aorta distal to the reconstruction site by means of stenting resulted in better haemodynamic outcomes.

Hybrid surgical management of a patient with an aneurysm of the arch and descending portion of the right-sided aorta combined with type B dissection and decompensated tracheal stenosis

The right-sided aorta is a rare congenital abnormality of the cardiovascular system encountered in 0.05-0.1% of cases during roentgenological examinations and in 0.04-0.1% of cases of autopsy series. Given utterly low prevalence of this pathology, we considered it wise to present herein our own case report dealing with hybrid surgical management of a patient suffering from an aneurysm of both the arch and descending portion of the right-sided aorta combined with type B dissection thereof and decompensated tracheal stenosis. The first stage of the operation consisted in prosthetic repair of the distal third of the arch and the descending portion of the aorta with the "Vascutek" stent graft 20 mm with type 1 haemodynamical correction (i. e., re-establishing the blood flow into the true channel in the zone of the distal anastomosis) in the conditions of extracorporeal circulation (EC) and bihemispheric antegrade cerebral perfusion ACP, followed by replantation of the left subclavian artery ostium into the left common carotid artery. An aneurysmal growth rate of more than 1 cm a year was considered an absolute indication for the second stage of correction of the aortic pathology concerned. The second stage included stenting of the thoracic portion of the aorta. The TF262C150X Valiant thoracic stent graft was implanted into the area of the distal anastomosis with a conduit, followed by positioning the TF 323C150X Valiant thoracic system inserted into the distal end of the first stent. The use of hybrid techniques (a combination of open and endovascular interventions) predetermined the success of surgical management of the patient presenting with dissection of the right-sided aorta.

Thoracic aortic dissection in a 38-year-old man

A few days before Christmas, a flight team was activated for an interfacility transfer of a 38-year-old man with a history of hypertension and spinal stenosis diagnosed with a thoracic aortic dissection. The patient was presented to a local community hospital complaining of nearly 5 days of left-sided rib pain. This afternoon when he stood up from a chair, he experienced a near-syncopal episode. Concurrently, he had an abrupt onset of a tearing sensation in his chest that radiated to thoracic spine in the region between his shoulder blades. Ground emergency medical services (EMS) was called, and the patient was transported to the community hospital. During the initial transport and evaluation by the emergency department (ED) staff, the patient was noted to be hypertensive, with a systolic blood pressure greater than 180 mmHg. In the ED, the patient received aspirin, morphine, and Lopressor. He underwent a chest x-ray (Figure 1) and computed tomography (CT) scan and was diagnosed with a type B thoracic aorta dissection, which was noted to start on the descending thoracic aorta distal to the left subclavian artery and extend to the level of the celiac trunk (Figure 2). Despite the initial beta blockade, the patient was noted to be profoundly hypertensive, with initial blood pressure greater than 190 mmHg systolic. The flight team was activated for hemodynamic management and rapid transport to a facility capable of vascular and cardiothoracic surgery.

[The effects of pulsatile blood flow on thoracic aortic dissection]

By virtue of computational fluid dynamics and the fundamental principles of hemodynamics, this paper gives numerical simulations and analyses of blood flow in the human thoracic aorta. The distributive features of velocity and pressure of the blood flow are obtained with the use of initial parabolic pulsatile blood flow. The numerical results show that, due to the angularity of thoracic aorta and due to the branch arteries, the distributions of velocity and pressure display marked difference, especially for the horizontal velocity, in the thoracic aorta connecting with the second and third branch artery, which indicate the place where thoracic aortic dissection often happens.

Simultaneous surgery for chronic aortic dissection and adrenal adenoma with primary aldosteronism

A 38-year-old man had Stanford type B chronic aortic dissection. Blood pressure was difficult to control, and further examination revealed primary aldosteronism. Magnetic resonance images showed a 1-cm nodule in the left adrenal gland. Graft replacement for aortic dissection under extracorporeal circulation and resection of the left adrenal gland were undertaken simultaneously. The postoperative course was uneventful, and blood pressure was controlled without antihypertensive drugs.