Mechanosensing via a GpIIb/Src/14-3-3ζ axis critically regulates platelet migration in vascular inflammation.

Platelets are not only the first responders in thrombosis and hemostasis but also central players in inflammation. Compared with platelets recruited to thrombi, immune-responsive platelets use distinct effector functions including actin-related protein complex 2/3-dependent migration along adhesive substrate gradients (haptotaxis), which prevents inflammatory bleeding and contributes to host defense. How platelet migration in this context is regulated on a cellular level is incompletely understood. Here, we use time-resolved morphodynamic profiling of individual platelets to show that migration, in contrast to clot retraction, requires anisotropic myosin IIa-activity at the platelet rear which is preceded by polarized actin polymerization at the front to initiate and maintain migration. Integrin GPIIb-dependent outside-in signaling via Gα13 coordinates polarization of migrating platelets to trigger tyrosine kinase c-Src/14-3-3ζ-dependent lamellipodium formation and functions independent of soluble agonists or chemotactic signals. Inhibitors of this signaling cascade, including the clinically used ABL/c-Src inhibitor dasatinib, interfere predominantly with the migratory capacity of platelets, without major impairment of classical platelet functions. In murine inflammation models, this translates to reduced migration of platelets visualized by 4D intravital microscopy, resulting in increased inflammation-associated hemorrhage in acute lung injury. Finally, platelets isolated from patients with leukemia treated with dasatinib who are prone to clinically relevant hemorrhage exhibit prominent migration defects, whereas other platelet functions are only partially affected. In summary, we define a distinct signaling pathway essential for migration and provide novel mechanistic insights explaining dasatinib-related platelet dysfunction and bleeding.

Mitochondrial respiration in peripheral arterial disease depends on stage severity.

Peripheral arterial disease (PAD) is an increasing cause of morbidity and its severity is graded based on clinical manifestation. To investigate the influence of the different stages on myopathy of ischemic muscle we analysed severity-dependent effects of mitochondrial respiration in PAD. Eighteen patients with severe PAD, defined as chronic limb-threatening ischemia, 47 patients with intermittent claudication (IC) and 22 non-ischemic controls were analysed. High-resolution respirometry (HRR) was performed on muscle biopsies of gastrocnemius and vastus lateralis muscle of patients in different PAD stages to investigate different respiratory states. Results from HRR are given as median and interquartile range and were normalized to citrate synthase activity (CSA), a marker for mitochondrial content. In order to account for inter-individual differences between patients and controls, we calculated the ratio of O2-flux in gastrocnemius muscle over vastus muscle ('GV ratio'). CSA of the gastrocnemius muscle as a proxy for mitochondrial content was significantly lower in critical ischemia compared to controls. Mitochondrial respiration normalized to CSA was higher in IC compared to controls. Likewise, the GV ratio was significantly higher in IC compared to control. Mitochondrial respiration and CSA of PAD patients showed stage-dependent modifications with greater changes in the mild PAD stage group (IC).

Isolated Ruptured Paravisceral Penetrating Aortic Ulcers.

BACKGROUND: The goal of this study is to investigate the clinical presentation, treatment options, and outcomes of the patients with isolated ruptured paravisceral penetrating aortic ulcers (PV-PAU). METHODS: All patients presenting with acute aortic syndrome from 2015 to 2020 were screened, of which patients with isolated ruptured PV-PAU were included in this retrospective study. Study endpoints were the assessment of treatment options, technical success, and clinical outcome. Outcome measures included major perioperative complications and mortality. RESULTS: Sixteen patients (11 men; median age 68; IQR 60 - 75 years) presented with isolated ruptured PV-PAU were included in this study. The median follow-up was 25 months (range 1 - 51). Ruptured PV-PAUs represented 12.3% of the ruptured aortic aneurysms in all locations. PV-PAUs were found in segment A (n = 8, 50%), segment B (n = 5, 31%), and segment C (n = 3, 19%). PV-PAUs showed a mean protrusion distance of 27±10 mm, a mean neck diameter of 21 ± 7 mm, and maximal aortic diameter of 50 ± 11 mm. Five patients (31%) showed hemodynamic instability on admission and needed intense fluid resuscitation. Of those, 2 patients needed urgent laparotomy with a fast transabdominal supraceliac aortic clamping, one needed an aortic balloon occlusion to obtain rapid aortic control. The open aortic repair was the most frequently performed surgery (11/16, 69%), followed by hybrid procedures (3/16) and parallel graft chimney technique (2/16). Two patients died during the follow-up, calculating for in-hospital and 1-year mortality rates of 6 - 12%, respectively. The postoperative morbidity rate was 31%. Postoperative complications included acute renal failure (31%), pneumonia (25%), and 1case of ischemic colitis (6%). No spinal cord ischemia was reported. CONCLUSIONS: Ruptured PV-PAU is a rare and challenging diagnostic and therapeutic entity. Open aortic repair seems to be a reliable option in treating patients with isolated ruptured PV-PAUs. Hybrid procedures and parallel stent-graft techniques can only be used in selected patients.

Perioperative risk prediction using the POSSUM and V-POSSUM models in symptomatic carotid stenosis.

Background: This study aimed to evaluate risk factors for adverse outcomes and perioperative stroke and death in patients with symptomatic carotid stenosis undergoing open endarterectomy (CEA). The second objective was to assess the predictive value of the POSSUM and V-POSSUM models for predicting morbidity and mortality from CEA in symptomatic carotid stenosis. Patients and methods: A retrospective observational study of all patients admitted to a single center who underwent CEA for symptomatic carotid stenosis was performed. 320 patients from 1999 to 2013 were included. Postoperative complications, 30-day survival, and stroke rates were recorded. The observed outcomes were compared to the POSSUM and V-POSSUM expected mortality (observed to expected ratio (O:E)). Results: The mean age was 68.1±10.0 years. 215 patients were male (67%). Risk factors for surgical complications were: age, with a higher risk in both groups of less than 60 years and more than 75 years of age (p=0.04), a higher ASA score (p=0.04), and hyperlipidemia (p=0.017). Risk factors for the combined endpoint stroke or death were a higher ASA category (p<0.001), stroke as indication for CEA (p 0.022), and a high degree of stenosis (p=0.019). For POSSUM predicted mortality, there was a good O:E ratio in the two lowest risk groups, but a 2-fold overprediction of death or stroke in the two high-risk strata. The area under the curve (AUC) was 0.58 (95% CI: 0.43-0.73). The V-POSSUM showed a better fit in the high-risk groups, but an underprediction of mortality in the low-risk strata. Conclusions: Age and comorbid conditions are risk factors for adverse outcomes after CEA. The V-POSSUM model is better than POSSUM to predict postoperative death and stroke after CEA in patients with symptomatic carotid stenosis and a high preoperative physiological score. In patients with low physiological scores, both POSSUM and V-POSSUM show a limited predictive value.

The effect of revascularization on recovery of mitochondrial respiration in peripheral artery disease: a case control study.

BACKGROUND: Peripheral arterial disease (PAD) is accompanied by myopathy characterized by mitochondrial dysfunction. The aim of this experimental study was to investigate the effect of revascularization procedures on mitochondrial function in ischemic and non-ischemic muscle. METHODS: Muscle biopsies from patients with symptomatic stage IIB/III PAD caused by isolated pathologies of the superficial femoral artery were obtained from muscle regions within the chronic ischemic muscle (gastrocnemius) and from non-ischemic muscle (vastus lateralis) before and 6 weeks after invasive revascularization. High-resolution respirometry was used to investigate mitochondrial function and results were normalized to citrate synthase activity (CSA). Results are given in absolute values and fold over basal (FOB). RESULTS: Respiratory states (OXPHOS (P) and electron transfer (E) capacity) normalized to CSA decreased while CSA was increased in chronic ischemic muscle after revascularization. There were no changes in in non-ischemic muscle. The FOB of chronic ischemic muscle was significantly higher for CSA (chronic ischemic 1.37 (IQR 1.10-1.64) vs. non-ischemic 0.93 (IQR 0.69-1.16) p = 0.020) and significantly lower for respiratory states normalized to CSA when compared to the non-ischemic muscle (P per CSA chronic ischemic 0.64 (IQR 0.46-0.82) vs non-ischemic 1.16 (IQR 0.77-1.54) p = 0.011; E per CSA chronic ischemic 0.61 (IQR 0.47-0.76) vs. non-ischemic 1.02 (IQR 0.64-1.40) p = 0.010). CONCLUSIONS: Regeneration of mitochondrial content and function following revascularization procedures only occur in muscle regions affected by malperfusion. This indicates that the restoration of blood and oxygen supply are important mediators aiding mitochondrial recovery.

Aortoduodenal fistulas after endovascular abdominal aortic aneurysm repair and open aortic repair.

OBJECTIVE: In the present study, we have reported and compared aortoduodenal fistulas (ADFs) after endovascular abdominal aortic aneurysm repair (EVAR) vs after open aortic repair (OAR). METHODS: We retrospectively analyzed the data from patients treated for ADFs from January 2015 to May 2020 in our hospital. The clinical data, diagnostic procedures, and surgical options were evaluated. The primary endpoints of the present study were 30-day and 1-year mortality. The secondary endpoints were major postoperative complications. RESULTS: A total of 24 patients (20 men; median age, 69 years; range, 53-82 years) were admitted with ADFs after EVAR (n = 9) or OAR (n = 15). These patients accounted for ∼4.3% of all abdominal aortic aneurysm repairs in our hospital. The median interval from the initial aortic repair and the diagnosis of ADF was 68 months (range, 6-83 months) for the ADF-EVAR group and 80 months (range, 1-479 months) for the ADF-OAR group. Three patients in the ADF-EVAR group had refused surgical treatment owing to their high surgical risk. One patient in the ADF-OAR group had undergone removal of the aortic prosthesis without replacement. Of the remaining 20 patients, 12 (ADF-EVAR group, n = 4; ADF-OAR group, n = 8) had undergone in situ replacement of the aorta and 8 (ADF-EVAR group, n = 2; ADF-OAR group, n = 6) had undergone extra-anatomic reconstruction with aortic ligation. After a mean follow-up of 26 months, no patient had experienced early limb loss. However, one case of rupture of the venous graft (ADF-EVAR), one case of aortic stump blowout (ADF-OAR), and one case of a ureteroarterial fistula with a homograft (ADF-OAR) had occurred. Overall, the incidence of postoperative complications was significantly greater after ADF-OAR (93% vs 33%; P = .036). The most frequent bacteria involved in the blood cultures were Escherichia coli (25% of patients), and Candida spp. (61%) were the predominant pathogens found on intra-abdominal smears. The in-hospital mortality rates for the ADF-EVAR and ADF-OAR group were 22% and 13%, respectively. The corresponding 1 -year mortality rates were 22% and 33%. CONCLUSIONS: Patients with ADFs after EVAR or OAR have limited overall survival. In addition to the similar therapeutic approaches, we found no significant differences in postoperative mortality between these two uncommon pathologic entities. In our study, the overall postoperative morbidity seemed greater for the ADF-OAR group.

The Role of Mitochondrial Function in Peripheral Arterial Disease: Insights from Translational Studies.

Recent evidence demonstrates an involvement of impaired mitochondrial function in peripheral arterial disease (PAD) development. Specific impairments have been assessed by different methodological in-vivo (near-infrared spectroscopy, 31P magnetic resonance spectroscopy), as well as in-vitro approaches (Western blotting of mitochondrial proteins and enzymes, assays of mitochondrial function and content). While effects differ with regard to disease severity, chronic malperfusion impacts subcellular energy homeostasis, and repeating cycles of ischemia and reperfusion contribute to PAD disease progression by increasing mitochondrial reactive oxygen species production and impairing mitochondrial function. With the leading clinical symptom of decreased walking capacity due to intermittent claudication, PAD patients suffer from a subsequent reduction of quality of life. Different treatment modalities, such as physical activity and revascularization procedures, can aid mitochondrial recovery. While the relevance of these modalities for mitochondrial functional recovery is still a matter of debate, recent research indicates the importance of revascularization procedures, with increased physical activity levels being a subordinate contributor, at least during mild stages of PAD. With an additional focus on the role of revascularization procedures on mitochondria and the identification of suitable mitochondrial markers in PAD, this review aims to critically evaluate the relevance of mitochondrial function in PAD development and progression.

The NephroCheck bedside system for detecting stage 3 acute kidney injury after open thoracoabdominal aortic repair.

Acute kidney injury (AKI) is a common complication after complex aortic procedures and it is associated with relevant mortality and morbidity. Biomarkers for early and specific AKI detection are lacking. The aim of this work is to investigate the reliability of the NephroCheck bedside system for diagnosing stage 3 AKI following open aortic surgery. In this prospective, multicenter, observational study,- https://clinicaltrials.gov/ct2/show/NCT04087161 -we included 45 patients undergoing open thoracoabdominal aortic repair. AKI risk (AKIRisk-Index) was calculated from urine samples at 5 timepoints: baseline, immediately postoperatively and at 12, 24, 48, and 72 h post-surgery. AKIs were classified according to the KDIGO criteria. Contributing factors were identified in univariable and multivariable logistic regression. Predictive ability was assessed with the area under the receiver operator curve (ROCAUC). Among 31 patients (68.8%) that developed AKIs, 21 (44.9%) developed stage-3 AKIs, which required dialysis. AKIs were correlated with increased in-hospital mortality (p = .006), respiratory complications (p < .001), sepsis (p < .001), and multi-organ dysfunction syndrome (p < .001). The AKIRisk-Index showed reliable diagnostic accuracy starting at 24 h post-surgery (ROCAUC: .8056, p = .001). In conclusion, starting at 24 h after open aortic repair, the NephroCheck system showed adequate diagnostic accuracy for detecting the patients at risk for stage 3 AKIs.

A Modified Run-Off Resistance Score from Cross-Sectional Imaging Discriminates Chronic Critical Limb Ischemia from Intermittent Claudication in Peripheral Arterial Disease.

Atherosclerotic peripheral arterial disease (PAD) leads to intermittent claudication (IC) and may progress into chronic limb-threatening ischemia (CLTI). Scoring systems to determine the atherosclerotic burden of a diseased extremity have been developed. This study aimed to evaluate a modification of the run-off resistance (mROR) score for its usability in cross-sectional imaging. The mROR was determined from preoperative imaging of patients undergoing revascularization for PAD. A total of 20 patients with IC and 20 patients with CLTI were consecutively included. A subgroup analysis for diabetic patients was conducted. The mROR was evaluated for its correlation with disease severity and clinical covariates. Patients with CLTI were older; cardiovascular risk factors, diabetes, and ASA 4 were more frequent. The mROR scores were higher in CLTI than in IC. In diabetic patients, no difference was detected between CLTI and IC. In CLTI, non-diabetic patients had a higher mROR. The mROR score is positively correlated with the severity of PAD and can discriminate CLTI from IC. In diabetic patients with CLTI, the mROR is lower than in non-diabetic patients. The mROR score can be determined from cross-sectional imaging angiographies. It may be useful for clinicians helping with vascular case planning, as well as for scientific purposes.

Effect of Revascularization on Intramuscular Vascular Endothelial Growth Factor Levels in Peripheral Arterial Disease.

Vascular endothelial growth factor (VEGF) is a potent driver of angiogenesis, which may help to relieve ischemia in peripheral arterial disease (PAD). We aimed to investigate the role of intramuscular VEGF in ischemic and non-ischemic skeletal muscle in PAD patients before and after surgical or endovascular revascularization and different stages of PAD. Biopsies of the gastrocnemius and vastus muscles from twenty PAD patients with stenosis or occlusion of the superficial femoral artery were obtained both during revascularization and 8 weeks postoperatively. The gastrocnemius muscle was considered ischemic, while vastus muscle biopsies served as intraindividual controls. The levels of vascular endothelial growth factor in muscle lysates were then determined by ELISA. Preoperative VEGF levels were significantly higher in ischemic muscles compared to the controls (98.07 ± 61.96 pg/mL vs. 55.50 ± 27.33 pg/mL, p = 0.004). Postoperative values decreased significantly (p = 0.010) to 54.83 ± 49.60 pg/mL in gastrocnemius biopsies. No significant change was observed in vastus muscle biopsies, with mean postoperative VEGF values found at 54.16 ± 40.66 pg/mL. Since all patients still had indications for revascularization, impairment of angiogenesis mechanisms can be assumed. More research about angiogenesis in PAD is needed with the ultimate goal to improve conservative treatment.

Giant saccular aneurysm of the internal carotid artery with adhesion to the vagus nerve: A Case Report.

INTRODUCTION AND IMPORTANCE: Aneurysms of the carotid artery are rare and potentially a risk factor for developing neurological events. This case report describes the treatment of a giant saccular aneurysm of the right extracranial internal carotid artery (ICA) with adhesion to the vagus verve. CASE PRESENTATION: An 85-year-old female presented with an asymptomatic pulsating mass on the right neck. Ultrasonography and MR angiography revealed a giant aneurysm of the right internal carotid artery with a massive tortuosity. Intraoperatively, a massive adhesion of the vagus nerve to the aneurysm was found. A resection of the aneurysm followed by a spatulated end-to-end anastomosis was performed. Postprocedural neurological symptoms included a transient paralysis of the vagus nerve that recovered within six weeks. CLINICAL DISCUSSION: The treatment options of ICA aneurysms include open surgical and endovascular interventions. Endovascular treatment may be a good option for aneurysms with a particular morphology. However, open surgery is the favorable option for immense ICA aneurysms with a tortuous anatomical path. CONCLUSION: Aneurysm resection with end-to-end anastomosis is a possible surgical option in the case of tortuous extracranial ICA aneurysms. Leaving parts of the aneurysmal wall prevented occurring persisting damage of the adhesive vagus nerve.

Vascular surveillance by haptotactic blood platelets in inflammation and infection.

Breakdown of vascular barriers is a major complication of inflammatory diseases. Anucleate platelets form blood-clots during thrombosis, but also play a crucial role in inflammation. While spatio-temporal dynamics of clot formation are well characterized, the cell-biological mechanisms of platelet recruitment to inflammatory micro-environments remain incompletely understood. Here we identify Arp2/3-dependent lamellipodia formation as a prominent morphological feature of immune-responsive platelets. Platelets use lamellipodia to scan for fibrin(ogen) deposited on the inflamed vasculature and to directionally spread, to polarize and to govern haptotactic migration along gradients of the adhesive ligand. Platelet-specific abrogation of Arp2/3 interferes with haptotactic repositioning of platelets to microlesions, thus impairing vascular sealing and provoking inflammatory microbleeding. During infection, haptotaxis promotes capture of bacteria and prevents hematogenic dissemination, rendering platelets gate-keepers of the inflamed microvasculature. Consequently, these findings identify haptotaxis as a key effector function of immune-responsive platelets.