Safety of cerebrospinal fluid drainage in descending and thoracoabdominal aortic replacement surgery

Background

Spinal cord injury (SCI) remains a significant morbidity of surgical repair of descending thoracic aortic aneurysms (DTAA) and thoracoabdominal aortic aneurysms (TAAA). We present our 17-year experience with cerebrospinal fluid drainage (CSFD) as a protective strategy during open surgical repair of descending and thoracoabdominal aortic disease.

Methods

We conducted a retrospective chart review of 132 patients who underwent open surgical repair of DTAA and TAAA and dissections with concurrent use of CSFD for spinal cord protection. Information regarding survival, postoperative course, and complications related to CSFD use were extracted from electronic health records (EHR) and analyzed.

Results

Mean patient age was 65.4±13.0 years, and 82 (62.1%) were male. A CSFD was successfully inserted in all patients. The mean hospital length of stay after surgery was 12.2±11.2 days, and in-hospital mortality was 7.6%. Postoperative transient paresis was observed in 5 patients (3.8%), and permanent paraplegia was seen in 4 (3.0%). CSFD related complications were reported in 25 patients (19%). Complications included persistent cerebrospinal fluid (CSF) leakage, blood-tinged CSF (with subdural hematoma reported in 3 patients) and spinal cutaneous fistula in 9 (7%), 14 (11%), and 1 (1%), respectively. Long term survival was 50.9% at 15 years.

Conclusions

CSFD is associated with minor complications, without major sequalae. It is a safe practice and likely contributes innocuously to decreased SCI in patients undergoing open repair of DTAA and TAAA.

Efficacious elimination of crystal violet pollutant via photo-Fenton process based on Gd(2-x)La(x)Zr2O7 nanoparticles

The photo-Fenton process is an appropriate method of the Advanced Oxidation Process that is used in the photocatalysis of organic dyes like crystal violet (CV). La³⁺ ion substituted gadolinium zirconium oxide Gd_(2-x)La_(x)Zr₂O₇ nanopowders (x = 0.1, 0.2, 0.3, and 0.5) have been successfully prepared by using sol-gel auto-combustion method to be used for the efficient photocatalysis of CV with photo-Fenton process. The well-crystallized defect-fluorite, structured with space group: Fm-3m, was detected using X-ray diffraction analysis. The lattice parameters were found to increase with the evaluated La³⁺ ion concentration. The grain size of the synthesized powders increased with the increase in La³⁺ ion content. The SAED patterns depicted fluorite structured fluorite. UV/Vis. spectrophotometer was used for the determination of band gap energy of Gd_(2-x)La_(x)Zr₂O₇ nanopowders which increased with increasing La³⁺ ion content. It was found to enhance from 4 to 3.6 eV. The visible spectrophotometer was used for determining unknown concentrations during the photocatalysis process to assure the effectiveness of the process. Overall, results illustrate that the photo-Fenton reaction on Gd_(2-x)La_(x)Zr₂O₇ performed excellently in removing crystal violet (CV). The photo-remediation ratio of CV reached 90% within 1 h.

Role of Surface Adsorbates on the Photoresponse of (MO)CVD-Grown Graphene-MoS2 Heterostructure Photodetectors

A promising strategy toward ultrathin, sensitive photodetectors is the combination of a photoactive semiconducting transition-metal dichalcogenide (TMDC) monolayer like MoS₂ with highly conductive graphene. Such devices often exhibit a complex and contradictory photoresponse as incident light can trigger both photoconductivity and photoinduced desorption of molecules from the surface. Here, we use metal-organic chemical vapor deposition (MOCVD) to directly grow MoS₂ on top of graphene that is deposited on a sapphire wafer via chemical vapor deposition (CVD) for realizing graphene-MoS₂ photodetectors. Two-color optical pump-electrical probe experiments allow for separation of light-induced carrier transfer across the graphene-MoS₂ heterointerface from adsorbate-induced effects. We demonstrate that adsorbates strongly modify both magnitude and sign of the photoconductivity. This is attributed to a change of the graphene doping from p- to n-type in case adsorbates are being desorbed, while in either case, photogenerated electrons are transferred from MoS₂ to graphene. This nondestructive probing method sheds light on the charge carrier transfer mechanisms and the role of adsorbates in two-dimensional (2D) heterostructure photodetectors.

Optical Probing of Crystal Lattice Configurations in Single CsPbBr3 Nanoplatelets

Quantum-confined nanostructures of CsPbBr₃ with luminescence quantum efficiencies approaching unity have shown tremendous potential for lighting and quantum light applications. In contrast to CsPbBr₃ quantum dots, where the fine structure of the emissive exciton state has been intensely discussed, the relationship among lattice orientation, shape anisotropy, and exciton fine structure in lead halide nanoplatelets has not yet been established. In this work, we investigate the fine structure of the bright triplet exciton of individual CsPbBr₃ nanoplatelets by polarization-resolved micro- and magnetophotoluminescence spectroscopy at liquid helium temperature and find a large zero-field splitting of up to 2.5 meV. A unique relation between the crystal structure and the photoluminescence emission confirms the existence of two distinct crystal configurations in such nanoplatelets with different alignments of the crystal axes with respect to the nanoplatelet facets. Polarization-resolved experiments eventually allow us to determine the absolute orientation of an individual nanoplatelet on the substrate purely by optical means.

Safety of perioperative cerebrospinal fluid drain as a protective strategy during descending and thoracoabdominal open aortic repair

Objective

We present our experience with routine application of the cerebrospinal fluid (CSF) drain (CSFD) during open aortic repair.

Methods

We retrospectively reviewed 100 patients with descending thoracic aortic aneurysm (DTAA) or thoracoabdominal aortic aneurysm (TAAA) or who underwent CSFD insertion before open repair between 2006 and 2017. All CSFDs were inserted by the cardiovascular anesthesia team. The goal was to keep intracranial pressure <10 mm Hg during the surgical procedure by draining CSF at a rate of 20 to 30 mL/h. Postoperatively, CSFD was set to maintain the lumbar pressure <10 mm Hg to reduce the risk of postoperative paraplegia. CSFD was part of our standard cord protection regimen.

Results

The mean patient age was 65.4 ± 11.7 years, and 60 (60%) were male. A CSFD was successfully inserted in all patients. The mean hospital length of stay was 11.9 ± 11.8 days, and hospital mortality was 6%. Postoperative transient paresis was observed in 4 patients (4%), and permanent paraplegia was seen in 2 (2%). CSFD-related complications were reported in 14 patients (14%). Complications included persistent CSF leakage and blood-tinged CSF with and without intracranial hemorrhage and spinal cutaneous fistula in 7 (7%), 9 (9%), and 1 (1%), respectively. Long-term survival was excellent (68.4% at 10 years).

Conclusions

CSFD is a safe practice when applied routinely as an adjunct strategy to prevent paraplegia in surgical management of DTAA and TAAA. We feel that this contributed to good early and late clinical results.

Increased Virulence of Descending Thoracic and Thoracoabdominal Aortic Aneurysms in Women

BACKGROUND

This study evaluates sex differences in the natural history of descending thoracic and thoracoabdominal aortic aneurysms (DTTAAs).

METHODS

In all, 907 patients with descending thoracic and thoracoabdominal aortic sizes greater than 3 cm were retrospectively reviewed. Growth rate estimates were performed utilizing an instrumental variables approach. Yearly complication rates as a function of aortic size were computed.

RESULTS

There were 615 men (67.8%) and 292 women (32.2%) treated between 1990 and 2018, with mean aortic diameters of 4.1 ± 1.4 cm and 4.8 ± 1.6 cm, respectively (P < .001). The mean growth rate of DTTAAs was 0.17 cm per year in men and 0.25 cm per year in women (P < .001), increasing with increasing aneurysm size. Dissection, rupture, or aortic death or the combination of the three occurred at double the rate for women compared with men (5.8% vs 2.3% per year for the combined endpoint). Diameter of DTTAA greater than 5 cm was associated with 26.3% (male) and 33.1% (female) average yearly rates of the composite endpoint of rupture, dissection, and death (P < .05). The probability of fatal complications (rupture and death) increased sharply at 5.75 cm in both sexes. Between 4.5 and 5.75 cm, there was another hinge-point of higher probability of fatal complications among women.

CONCLUSIONS

Women diagnosed with DTTAA fare worse. Faster aneurysm growth and higher rates of dissection, rupture, and aortic death are apparent among women. Current guidelines recommend surgical intervention at 5.5 to 6 cm for DTTAAs without sex considerations. Our findings suggest that increased virulence of DTTAA in women may indicate surgery at a somewhat smaller diameter.

Left Atrial to Femoral Artery Full Cardiopulmonary Bypass: A Novel Technique for Descending and Thoracoabdominal Aortic Surgery

Left atrial-femoral artery (LA-FA) bypass with a centrifugal pump and no oxygenator is commonly used for descending and thoracoabdominal aortic (DTAA) operations, mitigating the deleterious effects of cross-clamping. We present our initial experience performing DTAA replacement under LA-FA (left-to-left) cardiopulmonary bypass (CPB) with an oxygenator. DTAA replacement under LA-FA bypass with an oxygenator was performed in 14 consecutive patients (CPB group). The pulmonary vein and femoral artery (or distal aorta) were cannulated and the full CPB machine were used, including oxygenator, roller pump, pump suckers, and kinetically enhanced drainage. The CPB group was compared with 50 consecutive patients who underwent DTAA replacement utilizing traditional LA-FA bypass without an oxygenator (LA-FA group). Perioperative data were collected and statistical analyses were performed. All CPB patients maintained superb cardiopulmonary stability. The pump sucker permitted immediate salvage and return of shed blood. Superb oxygenation was maintained at all times. High-dose full CPB heparin was reversed without difficulty. The CPB group required markedly fewer blood transfusions than the LA-FA group (2.21 vs. 5.88 units, p  < 0.004). The 30-day mortality rate was 7.1% ( n  = 1) and there were no paraplegia cases in the CPB group versus 7 (14%) deaths and 3 (6%) paraplegia cases in the LA-FA group. Traditional LA-FA bypass without an oxygenator avoids high-dose heparin. In the present era, heparin reversal is more secure. Our experience finds that the novel application of LA-FA CPB with an oxygenator is safe and suggests improved hemodynamics (immediate return of shed blood) and a hemostatic advantage (avoidance of loss of coagulation factors in the cell saver).

Natural history of descending thoracic and thoracoabdominal aortic aneurysms

OBJECTIVES

Elucidating critical aortic diameters at which natural complications (rupture, dissection, and death) occur is of paramount importance to guide timely surgical intervention. Natural history knowledge for descending thoracic and thoracoabdominal aortic aneurysms is sparse. Our small early studies recommended repairing descending thoracic and thoracoabdominal aortic aneurysms before a critical diameter of 7.0 cm. We focus exclusively on a large number of descending thoracic and thoracoabdominal aortic aneurysms followed over time, enabling a more detailed analysis with greater granularity across aortic sizes.

METHODS

Aortic diameters and long-term complications of 907 patients with descending thoracic and thoracoabdominal aortic aneurysms were reviewed. Growth rates (instrumental variables approach), yearly complication rates, 5-year event-free survival (Kaplan-Meier), and risk of complications as a function of aortic height index (aortic diameter [centimeters]/height [meters]) (competing-risks regression) were calculated.

RESULTS

Estimated mean growth rate of descending thoracic and thoracoabdominal aortic aneurysms was 0.19 cm/year, increasing with increasing aortic size. Median size at acute type B dissection was 4.1 cm. Some 80% of dissections occurred below 5 cm, whereas 93% of ruptures occurred above 5 cm. Descending thoracic and thoracoabdominal aortic aneurysm diameter 6 cm or greater was associated with a 19% yearly rate of rupture, dissection, or death. Five-year complication-free survival progressively decreased with increasing aortic height index. Hazard of complications showed a 6-fold increase at an aortic height index of 4.2 or greater compared with an aortic height index of 3.0 to 3.5 (P < .05). The probability of fatal complications (aortic rupture or death) increased sharply at 2 hinge points: 6.0 and 6.5 cm.

CONCLUSIONS

Acute type B dissections occur frequently at small aortic sizes; thus, prophylactic size-based surgery may not afford a means for dissection protection. However, fatal complications increase dramatically at 6.0 cm, suggesting that preemptive intervention before that criterion can save lives.

Symptoms Matter: A Symptomatic but Radiographically Elusive Ascending Aortic Dissection

Symptoms attributable to a thoracic aortic aneurysm (TAA) are a separate indication for prophylactic repair, irrespective of aortic size. We present the case of a 56-year-old female with a history of a thoracic ascending aortic aneurysm (TAAA) and four other heart and arch vessel abnormalities who presented to us with chest pain radiating to her back. Computed Tomography and echocardiography showed no evidence of a dissection and revealed a maximal ascending aortic diameter of 4.2 cm. The patient subsequently underwent root-sparing ascending aortic and hemiarch replacement due to her threatening symptomatology. A focal dissection was discovered intraoperatively, resembling a similar case previously reported by our team.

Antithrombotic Therapy after Bioprosthetic Aortic Valve Replacement: A Therapeutic Morass

Valvular heart disease is a common pathologic condition that affects 6 million people in the United States and more than 100 million worldwide. The most common valvular disorder is aortic stenosis. Current American and European guidelines recommend surgical management for symptomatic aortic stenosis with low risk of perioperative complications and endovascular intervention for high-risk patients with multiple comorbidities. Considering the increasing volume of aortic valve replacement (AVR) with biological valves, it is very important to select the appropriate anticoagulant after surgical AVR. In this article, we review the impact of anticoagulation on immediate and remote complications after AVR.