Spinal cord protection in open and endovascular approaches to thoracoabdominal aortic aneurysms.

Despite advancements in surgical and postoperative management, spinal cord injury has been a persistent complication of both open and endovascular repair of thoracoabdominal and descending thoracic aortic aneurysm. Spinal cord injury can be explained with an ischemia-infarction model which results in local edema of the spinal cord, damaging its structure and leading to reversible or irreversible loss of its function. Perfusion of the spinal cord during aortic procedures can be enhanced by several adjuncts which have been described with a broad variety of evidence in their support. These adjuncts include systemic hypothermia, cerebrospinal fluid drainage, extracorporeal circulation and distal aortic perfusion, segmental arteries reimplantation, left subclavian artery revascularization, and staged aortic repair. The Authors here reviewed and discussed the role of such adjuncts in preventing spinal cord injury from occurring, pinpointing current evidence and outlining future perspectives.

Natural history of bicuspid aortic valves and ascending aortic aneurysms: Aortic center experience.

BACKGROUND AND AIM: The American Association of Thoracic Surgery published guidelines in 2018 encouraging regular surveillance rather than surgical intervention for ascending aortic aneurysms under 5.5 cm in both bicuspid aortic valve (BAV) and tricuspid aortic valve (TAV) patients. Since then, there have been limited studies reporting outcomes, especially by valve type. We aimed to analyze clinical outcomes including survival and aortic events in a cohort of BAV and TAV patients with ascending aortic aneurisms followed conservatively with routine computerized tomography  (CT) surveillance per current guidelines. METHODS: We followed 188 patients in our clinic between 2016 and 2019; 147 had two or more CT scans which allowed measurement of aortic growth. Echocardiogram data was evaluated for each patient. We identified similar cohorts of BAV (n = 32) and TAV (n = 64) patients matched by age, sex, hypertension, smoking history, family history of aortic disease, coronary artery disease, and hyperlipidemia. Univariate and multivariate analyses of the unmatched cohorts were performed. RESULTS: The mean aneurysm size was 4.3 ± 0.58 cm with 95% confidence interval (3.14, 5.46). This did not differ between BAV and TAV patients, nor did aneurysm growth rates. Overall adverse event rate (dissection, rupture, and death) was low for the entire cohort (BAV group, 3% and TAV group, 3.5%). Survival at 10 years for the entire cohort was 90 ± 32%. CONCLUSIONS: Regardless of aortic valve type, there was a similar natural history and low adverse event rate. In the absence of risk factors, conservative management can be accomplished with minimal risk to the patient.

Paraspinous muscle gene expression profiling following simulated staged endovascular repair of thoracoabdominal aortic aneurysm: exploring potential therapeutic pathways.

OBJECTIVES: Thoracic endovascular techniques for aneurysm repair offer less invasive alternatives to open strategies. Both approaches, however, are associated with the risk for neurological complications. Despite adjuncts to maintain spinal cord perfusion, ischaemia and paraplegia continue to occur during thoracoabdominal aortic aneurysm (TAAA) repair. Staging of such extensive procedures has been proven to decrease the risk for spinal cord injury. Archived biopsy specimens may offer insight into the molecular signature of the reorganization and expansion of the spinal collateral network during staged endovascular interventions in the setting of TAAA. METHODS: Biological replicates of total RNA were isolated from existing paraspinous muscle samples from 22 Yorkshire pigs randomized to 1 of 3 simulated TAAA repair strategies as part of a previous study employing coil embolization of spinal segmental arteries within the thoracic and lumbar spine. Gene expression profiling was performed using the Affymetrix GeneChip Porcine array. RESULTS: Microarray analysis identified 649 differentially expressed porcine genes (≥1.3-fold change, P ≤ 0.05) when comparing paralysed and non-paralysed subjects. Of these, 355 were available for further analysis. When mapped to the human genome, 169 Homo sapiens orthologues were identified. Integrated interpretation of gene expression profiles indicated the significant regulation of transcriptional regulators (such as nuclear factor кB), cytokine (including CXCL12) elements contributing to hypoxia signalling in the cardiovascular system (vascular endothelial growth factor and UBE2) and cytoskeletal elements (like dystrophin (DMD) and matrix metallopeptidase (MMP)). CONCLUSIONS: This study demonstrates the ability of microarray-based platforms to detect the differential expression of genes in paraspinous muscle during staged TAAA repair. Pathway enrichment analysis detected subcellular actors accompanying the neuroprotective effects of staged endovascular coiling. These observations provide new insight into the potential prognostic and therapeutic value of gene expression profiling in monitoring and modulating the arteriolar remodelling in the collateral network.

Successful Retrieval of a Migrated Shunt Catheter Causing Severe Pulmonary Insufficiency.

We report a case of a woman who presented with worsening shortness of breath due to a migrated ventriculoatrial shunt catheter into the pulmonary artery causing severe pulmonary insufficiency. She underwent surgical catheter removal. The majority of the catheter was easily retrieved; however, there were areas where the catheter was embedded into the myocardium, which would have posed a challenge with an endovascular approach.

Endovascular coil embolization of segmental arteries prevents paraplegia after subsequent thoracoabdominal aneurysm repair: an experimental model.

OBJECTIVES: To test a strategy for minimizing ischemic spinal cord injury after extensive thoracoabdominal aneurysm (TAAA) repair, we occluded a small number of segmental arteries (SAs) endovascularly 1 week before simulated aneurysm repair in an experimental model. METHODS: Thirty juvenile Yorkshire pigs (25.2 ± 1.7 kg) were randomized into 3 groups. All SAs, both intercostal and lumbar, were killed by a combination of surgical ligation of the lumbar SAs and occlusion of intercostal SAs with thoracic endovascular stent grafting. Seven to 10 days before this simulated TAAA replacement, SAs in the lower thoracic/upper lumbar region were occluded using embolization coils: 1.5 ± 0.5 SAs in group 1 (T13/L1), and 4.5 ± 0.5 SAs in group 2 (T11-L3). No SAs were coiled in the controls. Hind limb function was evaluated blindly from daily videotapes using a modified Tarlov score (0 = paraplegia, 9 = full recovery). After death, each segment of spinal cord was graded histologically using the 9-point Kleinman score (0 = normal, 8 = complete necrosis). RESULTS: Hind limb function remained normal after coil embolization. After simulated TAAA repair, paraplegia occurred in 6 of 10 control pigs, but in only 2 of 10 pigs in group 1; no pigs in group 2 had a spinal cord injury. Tarlov scores were significantly better in group 2 (control vs group 1, P = .06; control vs group 2, P = .0002; group 1 vs group 2, P = .05). A dramatic reduction in histologic damage, most prominently in the coiled region, was seen when SAs were embolized before simulated TAAA repair. CONCLUSIONS: Endovascular coiling of 2 to 4 SAs prevented paraplegia in an experimental model of extensive hybrid TAAA repair, and helped protect the spinal cord from ischemic histopathologic injury. A clinical trial in a selected patient population at high risk for postoperative spinal cord injury may be appropriate.

A prospective study of growth and rupture risk of small-to-moderate size ascending aortic aneurysms.

OBJECTIVE: The natural history of small-to-moderate size ascending aortic aneurysms is poorly understood. To follow these patients better, we have developed a method to objectively and reproducibly measure ascending aortic volume on the basis of gated contrast computed tomography scans. METHODS: From 2009 to 2011, 507 patients were referred for management of ascending aortic aneurysms. A total of 232 patients (46%) with small-to-moderate size aneurysms who did not have compelling indications for operation had measurement(s) of ascending aortic and total aortic volume; 166 patients had more than 1 scan, allowing measurement of growth. A total of 66 patients admitted to the emergency department without ascending aortic pathology served as a reference group. RESULTS: None of the patients experienced rupture, dissection, or death; 3 patients ultimately underwent operation. Ascending aortic volume and volume/total aortic volume differed for the surveillance and reference groups: 132.8 ± 39.4 mL versus 78.0 ± 24.5 mL; 38.3% ± 7.4% versus 29.1% ± 3.9%, respectively (both P < .001). Diameters at the sinotubular junction and mid-ascending aortic were 4.1 ± 0.6 cm and 4.4 ± 0.6 cm, respectively, for the surveillance group and 3.0 ± 0.4 cm and 3.2 ± 0.4 cm, respectively, for controls. The increase in ascending aortic volume was 0.95 ± 4.5 mL/year and 0.73% ± 3.7%/year (P = .007 and .012, respectively). Analysis of risk factors for ascending aortic growth revealed only the use of antithrombotic medication as possibly significant. CONCLUSIONS: Computed tomography volume measurements provide an objective method for ascertaining aortic size and monitoring expansion. Patients with small-to-moderate ascending aortic aneurysms who are carefully followed and managed appropriately have slow aneurysm growth and a small risk of rupture or dissection. Annual computed tomography screening may not be indicated, and elective resection-absent other surgical indications-is not necessary. The rupture/dissection risk for even larger aneurysms in carefully followed patients may be lower than currently believed.

Hypothermia for aortic surgery.

Hypothermic circulatory arrest has been used during aortic arch repairs with acceptable neurologic outcomes. Through the years, we have studied the effects of deep hypothermia on brain metabolism and perfusion both in a pig model and in surgical patients. Hypothermic circulatory arrest has also been used as a method of organ protection in the repair of thoracoabdominal aortic aneurysms. We summarize the clinical and laboratory studies to support the routine use of hypothermic circulatory arrest in clinical practice.

Predicting the risk for acute type B aortic dissection in hypertensive patients using anatomic variables.

OBJECTIVES: This study sought to identify possible anatomic predictors of acute type B aortic dissection (AAD) in hypertensive patients using multidetector computed tomography angiography (CTA). BACKGROUND: Although hypertension remains one of the most significant risk factors for AAD development, it is unlikely to be the only risk factor for AAD. Few studies have assessed anatomical predictors of AAD development. METHODS: CTA of normotensive patients without AAD (group 1, n = 35), hypertensive patients without AAD (group 2, n = 37), and hypertensive patients with AAD (group 3, n = 37) were compared. The length, diameter, volume, and tortuosity of the aorta as well as arch vessel angulation were measured for each patient and normalized to group 1 averages. Stepwise logistic regression identified significant anatomical associations; the model was validated based on 1,000 bootstrapped samples. RESULTS: The demographics of the groups were similar. The length of the proximal and entire aorta, the diameters in the proximal ascending aorta and aortic arch, and the aortic volumes were all greater (p < 0.0001, p = 0.0064 for ascending aortic diameter) in group 3 than in groups 1 and 2, as was entire aortic tortuosity (p < 0.0001). An AAD risk model was developed based on aortic arch diameter, length from the aortic root to the iliac bifurcation, and angulation of the brachiocephalic artery origin from the aorta. The bootstrap estimate of the area under the receiver operating curve was 0.974. CONCLUSIONS: Enlargement of the ascending aorta and aortic arch and increased aortic tortuosity reflect an aortopathy which enhances the probability of AAD. A model based on 3 anatomical variables demonstrates significant associations with AAD: it may allow identification by aortic imaging of the hypertensive patient most at risk, and permit implementation of aggressive medical management and consideration of pre-emptive surgery to prevent dissection.

Open repair of descending and thoracoabdominal aortic aneurysms and dissections in patients aged younger than 60 years: superior to endovascular repair?

BACKGROUND: The best option for repair of descending thoracic and thoracoabdominal aortic aneurysms (TAAA)-whether open operation or stent grafting-is increasingly a subject of controversy. We examined the results of open surgical repair in patients aged 60 years or younger to assess the value of conventional repair in younger patients. METHODS: From October 2002 to October 2010, 107 of 294 TAAA operations were in patients (75 men [70%]) aged a mean of 48 ± 9 years. Twelve patients (11%) had Marfan syndrome. Operations were elective in 101 (94%); previous aortic operations had been performed in 40 (37%). The most common indication for operation was chronic dissection, in 60 (56%); 5 (4.7%) had acute dissection, and rupture was present in 6 (5.6%). Descending repair was undertaken in 44 (41%), in 32 (73%) as an elephant trunk stage II. Deep hypothermic circulatory arrest was used in 46 (42.9%). Neurologic monitoring and cerebrospinal fluid drainage were routine. Median postoperative follow-up was 4.3 years (range, 2 days to 7.9 years). RESULTS: Overall 30-day mortality was 4.7%. Stroke occurred in 4 patients (3.7%) and paraplegia in 1 (0.9%). The linearized rate for reoperation for TAAA was 0.22/100 patient-years (1 patient in 448.8 patient-years). Survival at 1, 5, and 8 years was 90.5%, 89.4% and 80.5%, respectively. During follow-up, 1 patient with Ehlers-Danlos died of aortic complications at 4.5 years. CONCLUSIONS: Although direct comparison with stent grafting is limited by the diversity of patients and indications in published reports, our results suggest that open repair should be the modality of choice. Early mortality and neurologic complication rates are similar, if not superior, to endovascular repair for descending aortic and TAAAs. Open repair has proven durability and a very low rate of required reintervention, in contrast with endovascular repair.

Quality of life and survival of septuagenarians and octogenarians after repair of descending and thoracoabdominal aortic aneurysms.

OBJECTIVE: We assessed quality of life and survival in elderly patients after complex aortic operations to aid in surgical decision making. METHODS: A retrospective review was performed of 93 patients who underwent descending thoracic aneurysm or thoracoabdominal aortic aneurysm (TAAA) repair from 2002 to 2008. A Cox model was used for survival analysis. The SF-36 Item Health Survey was administered to assess postoperative quality of life in 39 patients and was compared with age- and gender-matched normal scores. RESULTS: The mean age at operation was 75 ± 4.1 years; 51% of patients were male. In-hospital mortality was 15%. One-year survival was 69%, and 5-year survival was 45%. Only acute respiratory distress syndrome was a predictor of in-hospital mortality (hazard ratio = 3.75; P < .01) and 1-year mortality (hazard ratio = 4.61; P < .001). After 1 year, patients enjoyed longevity equivalent to that of a normal age- and gender-matched population (standardized mortality ratio = 1.06; P = .81). Being male is a predictor of long-term survival (hazard ratio = 0.18; P < .05). For women, extremely low and high body mass indexes (quadratic term = 0.020; P < .05) with an inflection point of body mass index of 28 is a risk factor of long-term survival. Quality of life scores were similar to those of the general population except for lower vitality scores, (s-score = -0.67, 95% CI, -1.09 to -0.26). CONCLUSIONS: TAAA repair in this selected older surgical population yields acceptable survival beyond the first year. Among 1-year survivors, quality of life is similar to that of an age- and gender-matched population.

Imaging of vascular remodeling after simulated thoracoabdominal aneurysm repair.

OBJECTIVE: A better understanding of the response of the spinal cord blood supply to segmental artery (SA) sacrifice should help minimize the risk of paraplegia after both open and endovascular repair of thoracoabdominal aortic (TAA) aneurysms. METHODS: Twelve female juvenile Yorkshire pigs were randomized into 3 groups and perfused with a barium-latex solution. Pigs in group 1 (control) had infusion without previous intervention. Pigs in group 2 were infused 48 hours after ligation of all SAs (T4-L5) and those in group 3 at 120 hours after ligation. Postmortem computed tomographic scanning of the entire pig enabled overall comparisons and measurement of vessel diameters in the spinal cord circulation. RESULTS: We ligated 14.5 ± 0.8 SAs: all filled retrograde to the ligature. Paraplegia occurred in 38% of operated pigs. A significant increase in the mean diameter of the anterior spinal artery (ASA) was evident after SA sacrifice (P < .0001 for 48 hours and 120 hours). The internal thoracic and intercostal arteries also increased in diameter. Quantitative assessment showed an increase in vessel density 48 hours after ligation of SAs, reflected by an obvious increase in small collateral vessels seen on 3-dimensional reconstructions of computed tomographic scans at 120 hours. CONCLUSIONS: Remodeling of the spinal cord blood supply--including dilatation of the ASA and proliferation of small collateral vessels--is evident at 48 and 120 hours after extensive SA sacrifice. It is likely that exploitation of this process will prove valuable in the quest to eliminate paraplegia after TAA aneurysm repair.

Cerebral protection for aortic arch surgery: deep hypothermia.

The technical aspects of arch surgery have evolved considerably during the last 2 decades. The use of deep hypothermic circulatory arrest has been embraced by many cardiac surgeons to approach aortic arch aneurysms around the world. The branched graft technique that we have been using since the late 1990s has improved surgical outcomes and simplified the treatment considerably. We describe our technique of total arch replacement by using deep hypothermia and selective cerebral perfusion in aortic arch surgery.

Frequency of reoperations in patients with Marfan syndrome.

BACKGROUND: We undertook a retrospective study of the pattern of reoperations in surgical patients with Marfan disease. METHODS: Between 1985 and 2008, 83 Marfan patients (60 males, 23 females) underwent 155 aortic operations in our institution. Twenty-eight patients had acute dissection (22 type A, 6 type B), and two had aortic rupture. Mean age at initial operation was 32±13 years. Operations included valve-sparing or Bentall aortic root repair, and ascending aorta, arch, descending thoracic, thoracoabdominal aorta, and infrarenal aortic replacement. Sixty-one patients whose initial operation was elective (Group I) were compared with 22 patients with initial emergency surgery (Group II). RESULTS: Overall, 81/83 patients ultimately underwent root/ascending repair: 64% initially and 36% at reoperation. Operative mortality in Group I was 1.6% for both initial operations and reoperations vs 9.0% and 0% in Group II. Significant differences between Group I and Group II patients included: total reoperations (1 vs 3, p=0.05); arch operations (0 vs 1, p=0.003); descending thoracic aortic operations (0 vs 0.5, p=0.003); and total aortic segments replaced (1.6±1.0 vs 2.4±1.1, p=0.001). Survival at 5 and 10 years did not differ between Group I and II patients (87% and 71% vs 82% and 56%, p=0.19). CONCLUSIONS: Although reoperation occurs in about half of surgical Marfan patients, reoperative mortality is low. Patients with initial elective procedures fare better than those with initial emergency surgery: they have fewer subsequent operations, fewer aortic segments replaced, and trend toward improved survival. Elective root replacement should be seriously considered in any Marfan patient with significant root dilatation.

Selective cerebral perfusion for thoracic aortic surgery: association with neurocognitive outcome.

OBJECTIVES: Optimal brain protection for aortic arch surgery remains unclear. This prospective study examined neurocognitive outcomes in cardiac and thoracic aortic surgical patients, including a small cohort who underwent selective cerebral perfusion. METHODS: Fifty-seven adult cardiac and thoracic aortic surgical patients underwent preoperative and postoperative neurocognitive testing. Patients were divided into 3 groups. Group 1 patients underwent procedures with cardiopulmonary bypass alone (n = 24), group 2 patients with cardiopulmonary bypass and hypothermic circulatory arrest (n = 23), and group 3 patients with cardiopulmonary bypass, hypothermic circulatory arrest, and anterograde selective cerebral perfusion (n = 10). Changes in 14 neurocognitive test scores and 6 neurocognitive domain scores (Attention, Speed, Language, Memory, Executive Function, and Motor Function) were evaluated. RESULTS: Multiple regression analyses examining the relationships of cardiopulmonary bypass time, hypothermic circulatory arrest time, and selective cerebral perfusion time with change in cognitive test performance revealed that selective cerebral perfusion time (range, 39-83 minutes) was a significant predictor of decline in performance on memory and language tests. Hypothermic circulatory arrest (range, 14-40 minutes) and cardiopulmonary bypass (range, 70-369 minutes) times were unrelated to decline. CONCLUSIONS: Complex thoracic aortic repairs requiring prolonged selective cerebral perfusion were associated with decline in neurocognitive function. It is unclear whether the complexity of the repair necessitating prolonged selective cerebral perfusion or the perfusion technique itself contributed to neurocognitive decline. Prospective multicenter neurocognitive evaluations are necessary to assess the relative merits of current brain protection strategies in thoracic aortic surgery.

A propensity score-matched comparison of deep versus mild hypothermia during thoracoabdominal aortic surgery.

OBJECTIVE: By using deep hypothermic circulatory arrest and non-deep hypothermic circulatory arrest approaches, we examined the impact of distal ischemia time and temperature on intra-abdominal reversible adverse outcomes and permanent adverse outcomes during descending thoracic aortic and thoracoabdominal aortic aneurysm operations. METHODS: A retrospective review of all patients who underwent descending thoracic aortic and thoracoabdominal aortic aneurysm repair between January 2002 and December 2008 was undertaken, including relevant preoperative, intraoperative, and postoperative data, and followed by a propensity score-matched analysis. Of the total of 262 patients, 240 had data complete enough to permit analysis, and 90 were suitable for the propensity-matched study. Reversible adverse outcomes included renal failure, liver failure, and temporary hemodialysis. Permanent adverse outcomes included paraplegia, permanent hemodialysis, and 30-day mortality. RESULTS: Thirty-day mortality was 7.1% (17/240). Overall, reversible adverse outcomes developed in 40.8% of patients and permanent adverse outcomes developed in 10% of patients. The propensity score analysis identified statistically significant decreased odds of developing reversible adverse outcomes in patients undergoing deep hypothermic circulatory arrest (odds ratio, 0.32; confidence interval, 0.12-0.85). Specifically, significantly lower rates of acute renal failure (22% vs 46.4%, P = .03) and liver failure (17.8% vs 34.3%, P = .04) were observed in the deep hypothermic circulatory arrest group compared with the non-deep hypothermic circulatory arrest group. In addition, there were decreased odds of reversible adverse outcomes (odds ratio, 0.22; confidence interval, 0.06-0.79) developing in patients with a stage II elephant trunk procedure. CONCLUSIONS: During descending thoracic aortic and thoracoabdominal aortic aneurysm repairs, the use of deep hypothermic circulatory arrest results in improved postoperative adverse outcome rates compared with non-deep hypothermic circulatory arrest techniques. The development of reversible adverse outcomes is strongly associated with the development of permanent adverse outcomes.