Thoracovisceral segment aneurysm repair after previous infrarenal abdominal aortic aneurysm surgery

How does hemodynamics affect rupture tissue mechanics in abdominal aortic aneurysm: Focus on wall shear stress derived parameters, time-averaged wall shear stress, oscillatory shear index, endothelial cell activation potential, and relative residence time

An abdominal aortic aneurysm (AAA) is a critical health condition with a risk of rupture, where the diameter of the aorta enlarges more than 50% of its normal diameter. The incidence rate of AAA has increased worldwide. Currently, about three out of every 100,000 people have aortic diseases. The diameter and geometry of AAAs influence the hemodynamic forces exerted on the arterial wall. Therefore, a reliable assessment of hemodynamics is crucial for predicting the rupture risk. Wall shear stress (WSS) is an important metric to define the level of the frictional force on the AAA wall. Excessive levels of WSS deteriorate the remodeling mechanism of the arteries and lead to abnormal conditions. At this point, WSS-related hemodynamic parameters, such as time-averaged WSS (TAWSS), oscillatory shear index (OSI), endothelial cell activation potential (ECAP), and relative residence time (RRT) provide important information to evaluate the shear environment on the AAA wall in detail. Calculation of these parameters is not straightforward and requires a physical understanding of what they represent. In addition, computational fluid dynamics (CFD) solvers do not readily calculate these parameters when hemodynamics is simulated. This review aims to explain the WSS-derived parameters focusing on how these represent different characteristics of disturbed hemodynamics. A representative case is presented for spatial and temporal formulation that would be useful for interested researchers for practical calculations. Finally, recent hemodynamics investigations relating WSS-related parameters with AAA rupture risk assessment are presented. This review will be useful to understand the physical representation of WSS-related parameters in cardiovascular flows and how they can be calculated practically for AAA investigations.

Visceral segment aortic thrombus is associated with proximal aortic degeneration after infrarenal abdominal aortic aneurysm repair

OBJECTIVE

To identify predictors of aortic aneurysm formation at or above an infrarenal abdominal aortic aneurysm repair.

METHODS

A total of 881 infrarenal abdominal aortic aneurysm repairs were identified at a single institution from 2004 to 2008; 187 of the repairs were identified that had pre-operative and post-operative computed tomography imaging at least one year or greater to evaluate for aortic degeneration following repair. Aortic diameters at the celiac, superior mesenteric, and renal arteries were measured on all available computed tomographic scans. Aortic thrombus and calcification volumes in the visceral and infrarenal abdominal aortic segments were calculated. Multivariable modeling was used with log transformed variables to determine potential predictors of future aortic aneurysm development after infrarenal abdominal aortic aneurysm repair.

RESULTS

Of the 187 patients in the cohort, 100 had an open abdominal aortic aneurysm repair while 87 were treated with endovascular repair. Proximal aortic aneurysms developed in 26% (n = 49) of the cohort during an average of 72 ± 34.2 months of follow-up. After multivariable modeling, visceral segment aortic thrombus on pre-operative computed tomography imaging increased the risk of aortic aneurysm development above the infrarenal abdominal aortic aneurysm repair within both the open abdominal aortic aneurysm (hazard ratio 2.04, p = 0.033) and endovascular repair (hazard ratio 3.31, p = 0.004) cohorts. Endovascular repair was independently associated with a higher risk of future aortic aneurysm development after infrarenal abdominal aortic aneurysm repair when compared to open abdominal aortic aneurysm (hazard ratio 2.19, p = 0.025).

CONCLUSIONS

Visceral aortic thrombus present prior to abdominal aortic aneurysm repair and endovascular repair are both associated with an increased risk of future proximal aortic degeneration after infrarenal abdominal aortic aneurysm repair. These factors may predict patients at higher risk of developing proximal aortic aneurysms that may require complex aortic repairs.

Perioperative Outcome of Fenestrated and Branched Stent Grafting after Previous Open or Endovascular Abdominal Aortic Repair

BACKGROUND

To compare the perioperative outcome of patients treated with elective or urgent fenestrated and branched stent grafting (fbEVAR) for pararenal (pAAA) and thoracoabdominal aortic aneurysm (TAAA) after previous open with previous endovascular abdominal aortic repair.

METHODS

Single center retrospective analysis of all patients undergoing fbEVAR after previous open (post-open fbEVAR group) or endovascular abdominal aortic repair (post-endo fbEVAR group) between January 2015 and December 2017. Primary outcomes were technical success and in-hospital all-cause mortality.

RESULTS

We identified 42 patients undergoing fbEVAR after previous open or endovascular abdominal aortic repair during this period. Twenty-one patients (post-open fbEVAR group) had previous open abdominal aortic repair, 13 with a bifurcated and 8 with a tube graft. Of these, 2 patients presented with pAAA and 19 with TAAA. Twenty-one patients (post-endo fbEVAR group) had previous EVAR. Thirteen patients presented with pAAA, 3 of them with additional type Ia endoleak, 2 with stent-graft migration and 2 with previously failed fEVAR. Eight presented with TAAA. Median interval between previous repair and fbEVAR was 84 months (IQR 60-156) for the post-open fbEVAR group and 72 months (IQR 36-96) for the post-endo fbEVAR group (P = 0.746). Eighteen patients (86%) had branched stent grafting in the post-open versus 11 (52%) in the post-endo group (P < 0.01). In 2 patients in the post-open group, 3 renal arteries were not catheterized due to severe ostial stenosis, resulting in technical success of 91% in the post-open and 100% in the post-endo fbEVAR group. Four patients (19%) in the post-open fbEVAR group died in hospital, 2 due to cerebral hemorrhage and 2 due to pneumonia, and none in the post-endo fbEVAR group (P = 0.101). There were 5 nonstent-graft-related reinterventions, 2 (10%) in the post-open fbEVAR group and 3 (14%) in the post-endo fbEVAR group (P = 0.844). After 12 months there were 4 events in the post-endo fbEVAR group: one renal artery stent occluded, one renal artery stent required relining because of disconnection and 2 type II endoleaks were embolized with coils. There were no reinterventions in the post-open fbEVAR group during 12 months.

CONCLUSIONS

Fenestrated and branched repair after previous open or endovascular abdominal aortic repair appears safe with high technical success rate. There is no difference in the technical success and in-hospital all-cause mortality rates between fbEVAR after previous open or endovascular abdominal aortic repair.

Fenestrated and Branched Stent Grafting in Complex Aneurysmatic Aortic Disease: A Single-Center Early Experience

BACKGROUND

The aim of this study is to present our early experience and highlight the technical difficulties associated with the use of fenestrated and branched stent grafts to treat patients with juxtarenal abdominal aortic aneurysm (AAA), pararenal AAA, and thoracoabdominal aortic aneurysms (TAAAs).

METHODS

A prospectively held database maintained at our department was queried for patients who have undergone branched and fenestrated stent grafting for AAA or TAAA treatment. Indication for repair, comorbidity precluding open repair, technical challenges associated with the repair, as well as operative mortality, morbidity, and reintervention rate were evaluated.

RESULTS

A total of 8 patients underwent repair with a fenestrated or branched stent graft. All patients had aneurysmal degeneration of the juxtarenal aorta, pararenal aorta, and thoracoabdominal aorta not suitable to standard endovascular techniques. Two patients had a prior aortic repair, a failed migrated stent graft, and an old surgical tube graft after an open repair. One patient had a type III TAAA and 1 patient had a postdissection TAAA type I. For all patients, target vessel success rate was 96.4% (27/28) and mean hospital stay was 6.0 days (range 3-21). Thirty-day and 1-year mortality were 0%. Mean follow-up was 23 months (range 7-45). Two endoleaks occurred, 1 type III and 1 type II, which were treated endovascularly. No death or major complication occurred during follow-up.

CONCLUSIONS

Fenestrated and branched endovascular stent grafts can be used to repair juxtarenal AAA, pararenal AAA, and TAAA in patients with significant comorbidities. However, several technical challenges have to be overcome due to the unique complex aortic pathology of each patient.

A novel endovascular debranching technique using physician-assembled endografts for repair of thoracoabdominal aneurysms

OBJECTIVE

The objective of this study was to demonstrate a technique that uses physician-assembled endografts to make use of the benefits of parallel grafts while also providing for circumferential seal and fixation in repair of thoracoabdominal aneurysms in inoperable patients.

METHODS

A single-center all-comers retrospective analysis of 14 patients was performed that looked at the early outcomes of patients treated for thoracoabdominal aneurysms. Three Crawford type II, four type III, four type IV, and three type V thoracoabdominal aneurysms were treated. Contrast material, fluoroscopy time, length of stay, clinical success, and technical success were measured.

RESULTS

There was no in-hospital, 30-day, or 6-month mortality. We found two type III endoleaks in the early design. One required coil embolization. Average volume of contrast material and average fluoroscopy time were 76.9 mL and 119.1 minutes, respectively. Average length of stay was 10.5 days, and average procedure time was 251.2 minutes. Clinical success was observed in 78.6% of patients to date, and technical success was observed in 85.7% of patients.

CONCLUSIONS

Short-term results show that this approach is safe. The device can be safely implanted, is off-the-shelf, and can treat each of the Crawford thoracoabdominal aneurysm types. Finally, the assembly of off-the-shelf components may shorten the regulatory path for this physician-assembled endograft.

Open aortic repair up to previous abdominal aortic surgery

BACKGROUND

To determine whether direct open repair of thoracoabdominal aortic aneurysms after previous abdominal aortic surgery is a safe option.

METHODS

Ten patients were operated between January 2006 and January 2012. Mean age was 70 years (62-78 years). Four aneurysms (Crawford type III) were treated by firstly performed bypasses from the upper thoracic aorta to the celiac trunk, the superior mesenteric artery, and the left renal artery. Secondly performed aortic repair included revascularization of intercostal arteries identified as critical for spinal cord and the right renal artery. Similarly, the 6 aneurysms (Crawford type IV) were treated by firstly performed bypass from the upper thoracic aorta to the left renal artery before aortic repair.

RESULTS

The overall mortality and paraplegia rates were nil. The maximal creatinin sera variation was 48 ± 16% with return to the baseline level before discharge. Five patients presented with pulmonary complications. The duration of stay was 9.3 days (2-29) in the intensive care unit and 24 days (10-40) in the surgical unit. The mean follow-up was 35 months. No patient died during the follow-up.

CONCLUSIONS

In our experience, open redo aortic surgery appears to be safe. The main relevant point is the sequential reconstruction of the aorta including bypasses of the visceral branches that lowered the visceral ischemic damage because of high level aortic cross-clamping.

Clinical outcomes of hybrid repair for thoracoabdominal aortic aneurysms

BACKGROUND

Thoracoabdominal aortic aneurysm (TAAA) hybrid repair consists of aortic visceral branch rerouting followed by TAAA endograft exclusion. This technique has been shown to represent a technically feasible strategy in selected patients.

METHODS

We analyzed 52 high-risk patients who underwent hybrid TAAA repair between 2001 and 2012 in our centre with a variety of visceral rerouting configurations and of commercially available thoracic endografts. Thirty-seven simultaneous (71.2%) and 15 staged procedures (21.8%) were performed with a four-vessel revascularization in 18 cases (34.6%), a three-vessel revascularization in 11 cases (21.2%) and a two-vessel revascularization in 23 cases (44.2%).

RESULTS

No intraoperative deaths were observed. We recorded a perioperative mortality rate of 13.5% (n=7), including deaths from multiorgan failure (n=2), myocardial infarction (n=2), coagulopathy (n=1), pancreatitis (n=1) and bowel infarction (n=1). Perioperative morbidity rate was 28.8% (n=15), including 2 cases of transient paraparesis and 1 case of permanent paraplegia. Renal failure (n=5), pancreatitis (n=3), respiratory failure (n=3) and dysphagia (n=1) were also observed. At median follow-up of 23.9 months procedure-related mortality rate was 9.6%: two patients died from visceral graft occlusion and three from aortic rupture. There were three endoleaks and one endograft migration, none of which resulted in death. Five patients (9.6%) died as a consequence of unrelated events.

CONCLUSIONS

Typical complications of conventional TAAA open surgery have not been eliminated by hybrid repair, and significant mortality and morbidity rates have been recorded. Fate of visceral bypasses and incidence of endoleak and other endograft-related complications needs to be carefully assessed. Hybrid TAAA repair should currently be limited to high-risk surgical patients with unfit anatomy for endovascular repair.

High frequency of thoracic aneurysms in patients with abdominal aortic aneurysms

OBJECTIVE

To investigate the prevalence of thoracic aortic aneurysms (TAA) in patients with abdominal aortic aneurysms (AAA).

BACKGROUND

Different disease profiles between men and women treated for AAA have been reported. Reports regarding causes of death for treated AAA patients have shown an increased risk of death because of other aneurysms for women, possibly TAA. The prevalence of TAA in AAA patients is not well known.

METHODS

Data for AAA patients attending the outpatient clinic at a university hospital were analyzed (N = 1055). Patients who had undergone abdominal and thoracic computed tomography were included (n = 354). The diameter of the aorta was measured in the ascending, descending, and infrerenal aorta. Comorbid conditions were analyzed.

RESULTS

Mean age was 74 years, 23% were women. The presence of comorbid conditions did not differ between men and women except for a higher proportion of female smokers (P = 0.003). When sex-specific criteria were used, 100 patients (28%) had a TAA, 38 (48%) of the women compared with 62 (23%) of the men (P < 0.0001). Odds ratio for women compared with those of men to have a concurrent TAA was 3.09 (95% confidence interval, 1.84-5.22).

CONCLUSIONS

More than one fourth of patients with AAA attending a regular outpatient clinic have a concomitant TAA, and women are particularly affected. During the last decades, the therapeutic options for TAA patients have changed considerably. Physicians need to increase the efforts to investigate also the thoracic aorta in AAA patients.

Sobrevida tardia de pacientes submetidos à correção aberta eletiva de aneurisma de aorta abdominal

CONTEXTO: Os autores fazem uma revisão dos pacientes operados em hospital privado para determinar a causa da mortalidade tardia, a evolução dos demais segmentos da aorta e as complicações relacionadas à prótese. OBJETIVOS: Relatar o seguimento tardio de uma série de 76 casos operados eletivamente para a correção de aneurisma de aorta abdominal, no período de março de 1995 a janeiro de 2007. MÉTODOS: Convocação dos pacientes para uma consulta de retorno e daqueles que não puderam comparecer pessoalmente através de contato telefônico. RESULTADOS: A mortalidade operatória em 30 dias foi de 5,3%. A sobrevida tardia obtida por curva atuarial foi de 95% em 1 ano, 88% em 3 anos e 72% em 8 anos. As doenças cardiovasculares foram a principal causa de mortalidade tardia, seguidas das neoplasias malignas. A dilatação de segmento de aorta proximal à correção cirúrgica ocorreu em 9,7% dos pacientes operados, e as complicações relacionadas à prótese ocorreram em quatro casos (5,3%), sendo uma infecção de prótese, um pseudo-aneurisma proximal, um pseudo-aneurisma em ilíaca e uma oclusão de ramo. CONCLUSÃO: A cirurgia aberta para correção do aneurisma de aorta abdominal apresenta bom resultado em longo prazo, semelhante ao da literatura nacional e internacional, sendo uma boa opção para o paciente que tenha um baixo risco cirúrgico.

Hybrid approach to thoracoabdominal aortic aneurysms in patients with prior aortic surgery

OBJECTIVE

The hybrid approach to the repair of thoracoabdominal aortic aneurysm (TAAA), consisting of visceral aortic debranching with retrograde revascularization of the splanchnic and renal arteries and aneurysm exclusion using stent grafts, has been previously described and may be considered particularly appealing in high-risk patients, especially those who have undergone prior aortic surgery. This study analyzed prospectively recorded data of a series of high-risk patients with prior aortic surgery who underwent hybrid TAAA repair at our institute and contrasted the outcomes with those of a similar group of patients who underwent conventional open TAAA repair.

METHODS

Between 2001 and 2006, 13 patients (12 men) with a median age of 69.6 years (range, 35 to 82 years) underwent one-stage hybrid repair of TAAA (7 type I, 2 type II, 2 type IV, and 2 aneurysms of the visceral aortic patch). These patients, the hybrid group, had a history of aortic surgery (30.7% ascending, 30.7% descending, 46.1% abdominal aortic repair, and 15.4% redo TAAA) and were at high risk for open repair. The criteria used to define these patients as high risk and to indicate the need for hybrid treatment were American Society of Anesthesiologists (ASA) class 3 or 4 associated with a preoperative forced expiratory volume in 1 second (FEV1)<50%. In all cases, we accomplished partial or total visceral aortic debranching through (1) a previous visceral artery retrograde revascularization with synthetic grafts (single bypass, customized Y or bifurcated grafts), and (2) aortic endovascular repair with one of three different commercially produced stent grafts (Cook, W.L. Gore & Assoc, and Medtronic). We analyzed the results and compared the outcomes of the hybrid group with those of a similar group of 29 patients (25 men) with a median age 65.3 years (range, 58 to 79) selected from our overall series of 246 TAAA repairs between 1988 and 2005. These 29 patients, the conventionally treated group, were selected for having had aortic surgery (22% ascending, 38% descending, 42% abdominal aortic repair, and 10.3% redo TAAA), an ASA 3 or 4, a preoperative FEV1<50%, and a conventional open repair of TAAA (10 type I, 5 type II, 4 type III, 7 type IV, and 3 aneurysms of the visceral aortic patch).

RESULTS

In the hybrid group, 32 visceral bypasses were completed and endovascular TAAA repair was successful in all cases. No intraoperative deaths occurred. Perioperative mortality was 23%, and morbidity was 30.8% (renal failure in 2, respiratory failure in 1, and delayed transient paraplegia in 1). At a median follow-up of 14.9 months (range, 11 days to 59.4 months), all grafts were patent at postoperative computed tomography angiography and no aneurysm-related deaths, endoleak, stent graft migration, or morbidity related to visceral revascularization had occurred. No conventionally treated patients died intraoperatively. Perioperative mortality was 17.2% and morbidity was 44.8% (respiratory failure in 7, coagulopathy in 1, renal failure in 2, and paraplegia in 3). At a median follow-up of 5.4 years (range, 1.7 to 7.9 years), no significant complications related to aortic repair occurred, except for three patients (10.3%) with asymptomatic dilatation of the visceral aortic patch<5 cm undergoing radiologic surveillance.

CONCLUSION

Hybrid TAAA repair is technically feasible in selected cases. Perioperative morbidity and mortality were considerable in our subset of high-risk patients with prior aortic surgery, but no aneurysm-related or procedure-related complications were reported at mid-term follow-up. Hybrid TAAA repair did not lead to a significant improvement in outcomes compared with open TAAA repair in a similar group of patients. Larger series are required for valid statistical comparisons and longer follow-ups are necessary to evaluate the durability of hybrid repairs.

Preservation of Renal Function Utilizing Hypothermic Circulatory Arrest in the Treatment of Distal Thoracoabdominal Aneurysms (Types III and IV)

Although left heart bypass and hypothermia are often used in the performance of type I and type II thoracoabdominal aneurysms (TAAs), most of these more distal aneurysms are done utilizing the clamp and sew technique. Renal failure occurs between 8.6% to 39% in recent series of patients following surgery for type III and IV TAAs. The purpose of this study was to determine whether the use of hypothermic circulatory arrest in these cases would serve to protect renal function. All patients were operated on using hypothermic circulatory arrest. The kidneys were perfused with cold blood during the procedures, and renal artery bypasses were aggressively used (when stenoses greater than 50% were observed). The series describes 33 consecutive patients with type III and IV TAAs who were operated on utilizing hypothermic circulatory arrest with a core temperature of 15 degrees centigrade. All visceral and renal arteries were individually perfused; 20 patients had bypass grafts of their renal artery stenoses. Although six patients had renal failure preoperatively, only one developed postoperative renal failure. This was the patient who was operated on as an emergency for severe abdominal pain, back pain, and acidosis who was also the only hospital death. Of the remaining five patients with elevated creatinines preoperatively, four had postoperative decrease of the serum creatinine. One patient developed paraparesis and one developed a stroke. The median length of stay was 8 days. Consideration should be given to the use of hypothermic circulatory arrest in type III and IV TAAs for the preservation of renal function and improved overall results.