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.

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.

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.

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.

Sirolimus: A Rescue Drug to Control Complications of Extensive Venous Malformation.

Venous malformations represent a major sector of vascular anomalies. Most cases are asymptomatic or subclinical; however, large extensive lesions can cause severe disability and sometimes mortality. In this report, we present a successful case of sirolimus treatment in managing an extensive venous malformation in the pelvis of a 21-month-old boy who presented with life-threatening complications. With a history dating since the day 2 of life, the patient suffered from chronic bleeding due to scrotal skin ulcerations, in addition to recurrent attacks of severe bleeding per rectum necessitating hospital admission and blood transfusion (three attacks since the age of 7 months). Pelvic magnetic resonance image showed the typical findings of extensive venous malformation involving the pelvis, perineum, scrotum, and extending to the gluteal region. The lesion was seen totally encasing the anorectum with marked thickening of their walls almost occluding their lumen. Oral sirolimus (2 mg/m 2 ) was started with a target blood trough level of 5 to 10 ng/mL. Over a follow-up period of 5 months, there was obvious clinical improvement that included healing of skin lesions (scrotal ulcer) with complete re-epithelialization, absence of bleeding per rectum with improvement of constipation, and rise of hemoglobin level from 7.5 to 11.5 g/dL.

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).

Routine anterior spinal artery visualization prior to descending and thoracoabdominal aneurysm repair: High detection success.

BACKGROUND: Paraplegia is adevastating complication of open descending (DTAA) and thoracoabdominal aortic aneurysm (TAAA) repair. Despite major advances in imaging and surgical techniques, paraplegia continues to be problematic. We present our experience with routine application of enhanced imaging techniques to detect the anterior spinal artery (ASA) before DTAA and TAAA repair. METHODS: We retrospectively reviewed 177 patients with DTAA and TAAA who underwent imaging to detect the ASA before open surgical repair. High definition CT angiography (CTA) and dual energy CT scanning (DECT) were our modalities of choice with angiography used earlier and magnetic resonance angiography (MRA) used when CT was contraindicated. Descriptive statistics and χ2 analyses were conducted. RESULTS: The imaging protocol successfully detected the level of the ASA in 132 (74.5%) patients, utilizing CTA in 67, DECT in 28, spinal angiography in 31, and MRA in 6. Cross sectional modalities with advanced visualization technique (CT, DECT, and MRA) were more successful at detecting the ASA than angiography (80.72%, 82.35%, 75% vs 59.62%, respectively, P = .04). Concerted efforts were made not to leave the operating room without continuity of the ASA with the circulation (via limited resection, beveled anastomosis, or reimplantation). Transient lower extremity weakness was observed in 11 (6.2%) patients, and permanent paraplegia in 2 (1.12%) patients. CONCLUSION: Modern imaging technology provides multiple methodologies highly successful at detecting the ASA. The ASA can then be preserved intraoperatively, contributing to low paraplegia rates. We strongly recommend routine application of this technology to arm the surgeon with precise information about the specific patient's spinal cord blood supply.

Ascending Aortic Length and Risk of Aortic Adverse Events: The Neglected Dimension.

BACKGROUND: Little information is available regarding the longitudinal changes of the aneurysmal ascending aorta. OBJECTIVES: This study sought to outline the natural history of ascending thoracic aortic aneurysm (ATAA) based on ascending aortic length (AAL) and develop novel predictive tools to better aid risk stratification. METHODS: The ascending aortic diameters and lengths, and long-term aortic adverse events (AAEs) (rupture, dissection, and death) of 522 ATAA patients were evaluated using comprehensive statistical approaches. RESULTS: An AAL of ≥13 cm was associated with an almost 5-fold higher average yearly rate of AAEs compared with an AAL of <9 cm. Two AAL "hinge points" with a sharp increase in the estimated probability of AAEs were detected between 11.5 and 12.0 cm, and between 12.5 and 13.0 cm. The mean estimated annual aortic elongation rate was 0.18 cm/year, and aortic elongation was age dependent. Aortic diameter increased 18% due to dissection while AAL only increased by 2.7%. There was a noticeable improvement in the discrimination of the logistic regression model (area under the receiver-operating characteristic curve: 0.810) due to the introduction of aortic height index (AHI) (diameter height index + length height index). The AHIs <9.33, 9.38 to 10.81, 10.86 to 12.50, and ≥12.57 cm/m were associated with a âˆ¼4%, ∼7%, ∼12%, and ∼18% average yearly risk of AAEs, respectively. CONCLUSIONS: An aortic elongation of 11 cm serves as a potential intervention criterion for ATAA, which is even more reliable than diameter due to its relative immunity to dissection. AHI (including both length and diameter) is more powerful than any single parameter in this study.

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.

Decision-making algorithm for ascending aortic aneurysm: Effectiveness in clinical application?

OBJECTIVE: The risk of rupture and dissection in ascending thoracic aortic aneurysms increases as the aortic diameter exceeds 5 cm. This study evaluates the clinical effectiveness of a specific algorithm based on size and symptoms for preemptive surgery to prevent complications. METHODS: A total of 781 patients with nondissecting ascending thoracic aortic aneurysms who presented electively for evaluation to our institution from 2011 to 2017 were triaged to surgery (n = 607, 77%) or medical observation (n = 181, 24%) based on a specific algorithm: surgery for large (>5 cm) or symptomatic aneurysms. A total of 309 of 781 patients did not undergo surgery. Of these, 128 (16%) had been triaged to prompt repair but did not undergo surgery for a variety of reasons ("surgery noncompliant and overwhelming comorbidities" group). Another 181 patients (24%) were triaged to medical management ("medical" group). RESULTS: In the "surgery noncompliant and overwhelming comorbidities" versus the "medical" group, mean aortic diameters were 5 ± 0.5 cm versus 4.45 ± 0.4 cm and aortic events (rupture/dissection) occurred in 17 patients (13.3%) versus 3 patients (1.7%), respectively (P < .001). Later elective surgeries (representing late compliance in the "surgery noncompliant and overwhelming comorbidities group" or onset of growth or symptoms in the "medical" group) were conducted in 21 patients (16.4%) versus 15 patients (8.3%) (P = .04), respectively. Death ensued in 20 patients (15.6%) versus 6 patients (3.3%) (P < .001), respectively. In the "surgery noncompliant and overwhelming comorbidities" group, 7 of 20 patients died of definite aortic causes compared with none in the "medical" group. CONCLUSIONS: Patients with ascending thoracic aortic aneurysms who did not follow surgical recommendations experienced substantially worse outcomes compared with medically triaged candidates. The specific algorithm based on size and symptoms functioned effectively in the clinical setting, correctly identifying both at-risk and safe patients.

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.