Preoperative Spinal Arterial Supply Mapping Using Non-Selective Cone Beam Computed Tomography before Complex Aortic Repair

Pre-op spinal arterial mapping is crucial for complex aortic repair. This study explores the utility of non-selective cone beam computed tomography (CBCT) for pre-operative spinal arterial mapping to identify the Adamkiewicz artery (AKA) in patients undergoing open or endovascular repair of the descending thoracic or thoracoabdominal aorta at risk of spinal cord ischemia. Pre-operative non-selective dual-phase CBCT after intra-aortic contrast injection was performed in the aortic segment to be treated. The origin of detected AKA was assessed based on image fusion between CBCT and pre-interventional computed tomography angiography. Then, the CBCT findings were compared with the incidence of postoperative spinal cord ischemia (SCI). Among 21 included patients (median age: 68 years, 20 men), AKA was detected in 67% within the explored field of view, predominantly from T7 to L1 intercostal and lumbar arteries. SCI occurred in 14%, but none when AKA was not detected (p < 0.01). Non-selective CBCT for AKA mapping is deemed safe and feasible, with potential predictive value for post-surgical spinal cord ischemia risk. The study concludes that non-selective aortic CBCT is a safe and feasible method for spinal arterial mapping, providing promising insights into predicting post-surgical SCI risk.

Hemodynamic Patterns of Spinal Cord Perfusion in Thoracoabdominal Aortic Aneurysm Repair

Paraplegia in aortic surgery is due to its impact on spinal cord perfusion whose hemodynamic patterns (SCPHP) are not clearly defined. Detailed morphological analysis of vascular network and collateral network modifications within Monro-Kellie postulate due to the fixed theca confines was performed to identify SCPHP. SCPHP may begin with intraspinal "backflow" (I-BF), that is, hemorrhage from anterior and posterior spinal arteries, backward via the connected anterior and posterior radicular medullary arteries, through the increasing diameter and decreasing resistance of segmental arteries (SAs), off their aortic orifices outside vascular network at 0 operative field pressure. The I-BF blood bypasses both intra- and extraspinal capillary networks and causes depressurization (0 diastolic pressure) and full ischemia of dependent spinal cord. When the occlusion of those SAs orifices arrests I-BF, the hemodynamic pattern of intraspinal "steal" (I-S) may take place. The formerly I-BF blood, in fact, is now variably shared between the fraction maintained in its physiological intraspinal network and that keeping flowing as I-S through the extraspinal capillary network. I-S is, however, counteracted by the extraspinal "steal" from the connected mammary/paraspinous-independent extraspinal feeders, all physically competing for the same room left by the missed physiological SA direct aortic blood inflow. Steal phenomenon evolves within the 120-hour time frame of CNm, whose intraspinal anatomical changes may offer the physical basis within the Monro-Kelly postulate, respectively of the intraoperative and postoperative paraplegia. The current procedures could not prevent the unphysiological SCPHP but awareness of details of their various features may offer the basis for improvements tailored, to the adopted intra- and postoperative procedures.

Thoracoabdominal Aortic Aneurysm - The Branch First Technique

Surgical management of thoracoabdominal aortic aneurysms is complex. In particular, maintaining adequate spinal cord and reno-visceral protection during the operation can be challenging. We describe here a branch-first technique developed at our institution, endeavoring to minimized renal and visceral organ ischemic time, decrease risk of spinal cord injury, and provide a controlled and uncluttered field in which the surgeon can operate.

The impact of preoperative identification of the Adamkiewicz artery on descending and thoracoabdominal aortic repair

OBJECTIVE

To investigate the impact of preoperative identification of the Adamkiewicz artery (AKA) on prevention of spinal cord injury (SCI) through the multicenter Japanese Study of Spinal Cord Protection in Descending and Thoracoabdominal Aortic Repair (JASPAR) registry.

METHODS

Between January 2000 and October 2011, 2435 descending/thoracoabdominal aortic repairs were performed, including 1998 elective repairs and 437 urgent repairs, in 14 major centers in Japan. The mean patient age was 67 ± 13 years, and 74.2% were males. There were 1471 open repairs (ORs), including 748 descending and 137 thoracoabdominal extent [Ex] I, 136 Ex II, 194 Ex III, 115 Ex IV, and 138 Ex V, and 964 endovascular repairs (EVRs). Of the 2435 patients, 1252 (51%) underwent preoperative magnetic resonance or computed tomography angiography to identify the AKA.

RESULTS

The AKA was identified in 1096 of the 1252 patients who underwent preoperative imaging (87.6%). Hospital mortality was 9.2% (n = 136) in those who underwent OR and 6.4% (n = 62) in those who underwent EVR. The incidence of SCI was 7.3% in the OR group (descending, 4.2%; Ex I, 9.4%; Ex II, 14.0%; Ex III, 14.4%; Ex IV, 4.2 %; Ex V, 7.2%) and 2.9% in the EVR group. The risk factors for SCI in ORs were advanced age, extended repair, emergency, and occluded bilateral hypogastric arteries. In ORs of the aortic segment involving the AKA, having no AKA reconstruction was a significant risk factor for SCI (odds ratio, 2.79, 95% confidence interval, 1.14-6.79; P = .024).

CONCLUSIONS

In descending/thoracoabdominal aortic repairs, preoperative AKA identification with its adequate reconstruction or preservation, especially, in ORs of aortic pathologies involving the AKA, would be a useful adjunct for more secure spinal cord protection.

Spinal cord injury following thoracic and thoracoabdominal aortic repairs

Objective

To discuss the currently available approaches to prevent spinal cord injury during thoracic and thoracoabdominal aortic repairs.

Methods

We carried out a PubMed search up to 2013 using the Medical Subject Headings: “aortic aneurysm/surgery” and “spinal cord ischemia”; “aortic aneurysm, thoracic/surgery” and “spinal cord ischemia”; “aneurysm/surgery” and “spinal cord ischemia/cerebrospinal fluid”; “aortic aneurysm/surgery” and “paraplegia”. All 190 original articles satisfying our inclusion criteria were analyzed for incidence, predictors, and other pertinent variables related to spinal cord injury, and we compared the results in recent publications with those in earlier reports.

Results

The mean age of the 38,491 patients was 65.3 ± 4.9 years. The overall incidence of paraplegia and/or paraparesis was 7.1% ± 6.1% (range 0%–32%). The incidence of spinal cord injury before 2000, from 2001 to 2007, and 2008–2013 was 9.0% ± 6.7%, 7.0% ± 6.1%, and 5.9% ± 5.2%, respectively ( p = 0.019). Various predictors of spinal cord injury were identified, extent of disease being the most common. Modification of surgical techniques, use of adjuncts, and better understanding of spinal cord perfusion physiology were attributed to the decrease in postoperative spinal cord injury in recent years.

Conclusions

Spinal cord injury after thoracic and thoracoabdominal aortic repair poses a real challenge to cardiovascular surgeons. However, with evolving surgical strategies, identification of predictors, and use of various adjuncts over the years, the incidence of spinal cord injury after thoracic/thoracoabdominal aortic repair has declined. Embracing a multimodality approach offers a good insight into combating this grave complication.

Predictors of paraplegia with current thoracoabdominal aortic aneurysm repair

Background

Although the results of surgical repair of thoracoabdominal aortic aneurysm continue to improve, the incidence of paraplegia remains within a wide range depending on each institution. The purpose of this study was to find predictors of paraplegia following thoracoabdominal aortic aneurysm repair in our institute, using the current spinal cord protection strategies.

Methods

From January 2007 to December 2011, 200 consecutive patients underwent thoracoabdominal aortic aneurysm repair. Of these, 24 (12%) had Crawford extent I repair, 82 (41%) had extent II, 51 (25.5%) had extent III, 10 (5%) had extent IV, and 33 (16.5%) had extent V (modified by Safi). Aortic dissection was present in 101 (50.5%) patients. Adjuncts used during the procedures included left heart bypass in all patients, cerebrospinal fluid drainage in 164 (82%), and intercostal artery reimplantation in 76 (38%).

Results

There were 20 (10%) hospital deaths including 6 (3%) within 30 days; hospital mortality was 8.8% in elective operations. Postoperative complications included paraplegia in 17 (8.5%) patients, stroke in 5 (2.5%), and acute renal failure requiring dialysis in 5 (2.5%). Logistic regression analysis revealed that significant factors for the development of paraplegia were preoperative hypotension ( p = 0.005, odds ratio 18.5), intraoperative hypotension ( p = 0.001, odds ratio 77.6), and an open distal anastomosis technique ( p = 0.012, odds ratio 4.6).

Conclusions

The predictors of postoperative paraplegia in our institution were perioperative hypotension and an open distal anastomosis technique. Avoidance of these risk factors might diminish the incidence of postoperative paraplegia.

Intrathecal lactate as a predictor of early- but not late-onset spinal cord injury in thoracoabdominal aneurysmectomy

OBJECTIVE

To evaluate the role of intrathecal lactate as an early predictor of spinal cord injury during thoracoabdominal aortic aneurysmectomy.

DESIGN

Observational study.

SETTING

University hospital.

PARTICIPANTS

Forty-four consecutive patients scheduled to undergo thoracoabdominal aortic aneurysmectomy. Two patients had a type-B dissecting aneurysm while the other 42 patients suffered from degenerative aneurysm.

INTERVENTIONS

None.

METHODS

During surgery, samples of cerebrospinal fluid and arterial blood were withdrawn simultaneously to evaluate lactate concentration. Samples were collected at 4 fixed times during and after surgery: T1 (beginning of the intervention), T2 (15 minutes after aortic cross-clamping), T3 (just before unclamping), T4 (end of surgery).

MEASUREMENTS AND MAIN RESULTS

Mean lactate levels in cerebrospinal fluid rose consistently and steadily from the beginning of the intervention until after surgery (T1 = 1.83 mmol/L), T2 = 2.10 mmol/L, T3 = 2.72 mmol/L, T4 = 3.70 mmol/L). Seven patients developed spinal cord injury; two of them had delayed injury occurring 24 hours after the end of surgery; the remaining 5 had early onset. In this group of 5 patients, preoperative cerebrospinal fluid lactate levels were significantly (p = 0.04) higher than those of the other 37 patients preoperatively (2.12 ± 0.35 v 1.79 ± 0.29 mmol/L).

CONCLUSIONS

Preoperative cerebrospinal lactate concentration is elevated in patients who will develop early-onset spinal cord injury after thoracoabdominal aortic aneurysmectomy. This may allow a better stratification of these patients, suggesting a more aggressive strategy of spinal cord function preservation, such as systematic reimplanting of intercostal arteries, and possibly obtaining a better outcome.

Thromboendarterectomy and circulatory arrest

Thromboendarterectomy remains a high-risk procedure. The use of circulatory arrest as a technique to allow pulmonary artery visualization is associated with cerebral and organ damage secondary to the ischaemic insult. Application of techniques learned from thoracic aortic stenting and minimal invasive valvular surgery may mean that circulatory arrest becomes an uncommon accompaniment to thromboendarterectomy.