Paula Keschenau

The impact of selective visceral perfusion on intestinal macrohemodynamics and microhemodynamics in a porcine model of thoracic aortic cross-clamping.

INTRODUCTIONnDespite its presumed effectiveness and clinical use, the physiology of selective visceral perfusion combined with distal aortic perfusion during open thoracoabdominal aortic surgery has not been characterized. Thus, the aim of this study was to establish a translatable model of thoracic aortic-clamping to assess the effect of selective visceral perfusion with added distal aortic perfusion on local intestinal macrohemodynamics and microhemodynamics, intestinal histopathology, and markers of inflammation and intestinal damage.nnnMETHODSnA thoracolaparotomy was performed in 15 pigs, and the aorta was exposed, including the origins of celiac trunk and superior mesenteric artery. The animals were divided into three cohorts: control (I), thoracic aortic cross-clamping (II), and thoracic aortic cross-clamping with selective visceral perfusion plus distal aortic perfusion using extracorporeal circulation (III). Macrocirculatory and microcirculatory blood flow was assessed by transit time ultrasound volume flow measurements and fluorescent microspheres. Intestinal ischemia-reperfusion injury was determined by the analysis of perioperative intestinal fatty acid-binding protein (IFABP) and interleukin-8 (IL-8) levels and correlated with histopathologic changes.nnnRESULTSnSevere intestinal tissue injury and an inflammatory response were observed in cohort II compared with cohort III for IL-8 (38.2 vs 3.56 pg/mL; P = .04). The procedure in cohort III resulted in a flow and pressure-associated intestinal hypoperfusion compared with cohort I in the superior mesenteric artery (mean blood pressure, 24.1 ± 10.4 vs 67.2 ± 7.4 mm Hg; P < .0001; mean flow rates: 353.3 ± 133.8 vs 961.7 ± 310.8 mL/min; P < .0001). This was paralleled in cohort III vs cohort I by a significant mucosal injury (IFABP, 713 ± 307.1 vs 170 ± 115.4 pg/mL; P = .014) despite a profound recruitment of intestinal microcirculation (338% ± 206.7% vs 135% ± 123.7%; P = .05).nnnCONCLUSIONSnThis study reports a novel large-animal model of thoracic aortic cross-clamping that allows the study of visceral perfusion strategies. However, we demonstrated with IL-8 and IFABP measurements that thoracoabdominal aortic aneurysm surgery with selective visceral perfusion and distal aortic perfusion is superior to the clamp-and-sew technique, even though small intestinal tissue damage cannot be completely avoided by selective visceral perfusion and distal aortic perfusion. In any case, this model seems to be a platform to evaluate and optimize measures for gut wall protection.

Microcirculatory perfusion shift in the gut wall layers induced by extracorporeal circulation

OBJECTIVEnExtracorporeal circulation (ECC) is regularly applied to maintain organ perfusion during major aortic and cardiovascular surgery. During thoracoabdominal aortic repair, ECC-driven selective visceral arterial perfusion (SVP) results in changed microcirculatory perfusion (shift from the muscularis toward the mucosal small intestinal layer) in conjunction with macrohemodynamic hypoperfusion. The underlying mechanism, however, is unclear. Therefore, the aim of this study was to assess in a porcine model whether ECC itself or the hypoperfusion induced by SVP is responsible for the mucosal/muscular shift in the small intestinal wall.nnnMETHODSnA thoracoabdominal aortic approach was performed in 15 healthy pigs divided equally into three groups: group I, control; group II, thoracic aortic cross-clamping with distal aortic perfusion; and group III, thoracic aortic cross-clamping with distal aortic perfusion and SVP. Macrocirculatory and microcirculatory blood flow was assessed by transit time ultrasound volume flow measurement and fluorescent microspheres. In addition, markers for metabolism and intestinal ischemia-reperfusion injury were determined.nnnRESULTSnECC with a roller pump induced a significant switch from the muscularis and mucosal layer of the small intestine, even with adequate macrocirculation (mucosal/muscular perfusion ratio: group I vs II, P = .005; group I vs III, P = .0018). Furthermore, the oxygen extraction ratio increased significantly in groups II (>30%) and III (>40%) in the beginning of the ECC compared with the control (group I vs II, P = .0037; group I vs III, P = .0062). Lactate concentrations and pH values did not differ between groups I and II; but group III demonstrated a significant shifting toward a lactate-associated acidosis (lactate: group I vs III, P = .0031; pH: group I vs III, P = .0001).nnnCONCLUSIONSnWe demonstrated a significant shifting between the small intestinal gut wall layers induced by roller pump-driven ECC. The shift occurs independently of macrohemodynamics, with a significant effect on aerobic metabolism in the gut wall. Consequently, an optimal intestinal perfusion cannot be guaranteed by a roller pump; therefore, perfusion techniques need to be optimized.

Editor's Choice – Open Thoracic and Thoraco-abdominal Aortic Repair in Patients with Connective Tissue Disease

OBJECTIVE/BACKGROUNDnThe aim is to present current results of open complex aortic repair in patients with connective tissue disease (CTD).nnnMETHODSnThis was a retrospective cross-border, single centre study. From February 2000 to April 2016 72 aortic operations were performed on 65 patients with CTD (41 male, median age 41 years [range 19-70 years]). Fifty-six patients (86%) underwent at least one previous aortic repair (71 open, four endovascular), including 33 patients (51%) operated before at the site of the procedure reported here. The open procedures, counting eight emergency operations (11%), included aortic arch revision (nxa0=xa01; 1%), descending thoracic aortic repair (nxa0=xa011; 15%), TAAA type I repair (nxa0=xa012; 17%), type II repair (nxa0=xa029; 40%), type III repair (nxa0=xa012; 17%), and type IV repair (nxa0=xa05; 7%). Simultaneous repair of the ascending aorta and/or the aortic arch was performed in two (3%) and eight cases (11%), respectively. Seven patients (10%) underwent staged procedures. Median follow-up was 42 months (0.5-180 months).nnnRESULTSnThe in hospital mortality was 14% (nxa0=xa09) as a result of haemorrhage (nxa0=xa03/9), neurological (nxa0=xa03/9),xa0cardiac (nxa0=xa02/9), and pulmonary (nxa0=xa01/9) complications. Paraplegia and paraparesis occurred in one (2%) and three patients (5%), respectively. Seven patients (11%) required temporary dialysis; nonexa0needed permanent dialysis. Major complications were revision surgery for bleeding or haematoma (nxa0=xa020/65),xa0sepsis (nxa0=xa010/65), myocardial infarction/severe cardiac arrhythmia (nxa0=xa02/65), stroke (nxa0=xa02/65),xa0as well as multiorgan failure, abdominal compartment syndrome, mesenteric and peripheral ischaemia (all nxa0=xa01/65). Multivariate analysis identified an operating time >xa07xa0hours (pxa0=xa0.006) as an independent predictor of increased mortality. Freedom from re-intervention was 85%, 1 year survival was 80%, and overall survival was 75%.nnnCONCLUSIONnOpen TAA(A) repair is a durable therapy for patients with CTD. Often being performed as revision surgery, it can be associated with relevant risks and should therefore be reserved for specialised centres. Staged procedures and thus reducing operating time, if applicable, should be preferred.

Intraoperative Neuromonitoring for Prevention of Neurological Complications in Aortic Surgery

AIMnStroke and paraplegia are devastating complications of thoracic and thoracoabdominal aortic surgery. The aim of this study was to analyse the value of transcranial Doppler ultrasound (TCD), electroencephalogram (EEG) and motor-evoked potentials (MEP) in preventing neurological complications. Moreover, the principles, technology and surgical protocols are described.nnnPATIENTS AND METHODSnIn 2009, 22 patients (4 females, 18 males) underwent thoracic or thoracoabdominal open aortic repair. We performed 2 arches with descending aortic replacement, 5 arches with TAAA repair, 2 type II, 9 type III, 3 type IV and one type V TAAA aortic repair. In 6 patients, the neuromonitoring included TCD, EEG and MEPs. In 15 patients only MEP monitoring was necessary. In one patient who was operated on in an emergency setting, neuromonitoring was not performed. The surgical approach was a left thoracotomy in 3 and a left thoracolaparotomy in 19 patients. The surgical protocol included cerebrospinal fluid drainage (n=22), moderate (n=19) or deep hypothermia (n=2), and extracorporeal circulation (n=21) with retrograde aortic perfusion and selective cerebral and/or viscerorenal perfusion.nnnRESULTSnIn 21 patients, the neuromonitoring could be established successfully. Using TCD and EEG, a relevant cerebral ischaemia during supraaortic clamping was excluded. With a mean distal arterial pressure of 60 mmHg, the MEPs remained adequate in 15 patients (68.2%). Increasing of the blood pressure restored the MEPs in one patient. In 5 patients (22.7%), a reimplantation of segmental arteries (n=4) or of the left subclavian artery (n=1) re-established spinal cord perfusion, as indicated by restored MEPs. We had no absent MEPs at the end of the procedures. Delayed paraparesis developed in 2 patients with a haemodynamic instability during the postoperative course. Paraplegia was not observed.nnnCONCLUSIONnTCD, EEG and MEPs are reliable techniques to unmask cerebral or spinal cord ischaemia during aortic surgery. Immediate operative strategies based on neuromonitoring information prevent neurological complications in aortic surgery.

Treatment of blunt thoracic aortic injury in Germany—Assessment of the TraumaRegister DGU®

Purpose Using the data delivered by the German Trauma Register DGU® from 2002 till 2013, the value of different therapies of blunt thoracic aortic injury (BTAI) in Germany was analyzed. Methods Prospectively collected data of patients suffering from BTAI were retrospectively analyzed with focus on the different treatment modalities for grade I–IV injuries. Results 821 patients suffering from BTAI were identified: 51.6% (424) grade I injury, 35.4% (291) grade II or III injury and 12.9% (106) grade IV injury (77.5% men [44.94 ± 20.6 years]). The main patterns of injury were high- speed accidents and falls (78.0% [n = 640], 21.8% [n = 171] respectively). Significant differences between grade I and grade II/III as well as IV injuries could be assessed for the incidence of cardiopulmonary resuscitation, a Glasgow Coma Scale score below 8 and a systolic blood pressure below 90 mmHg (p-value: <0.001). In the primary admission subgroup, 44.1% (197/447) of the patients received best medical treatment, 55.9% received surgical intervention (250/447): Thereof 37.2% (93/250) received open surgery and 62.8% (147/250) had been treated by endovascular means. Significantly lower 24-h- and in-hospital-mortality rates were encountered after endovascular treatment for all gradings of BTAI (p-value: <0.001). Yet this subgroup of patients showed the lowest incidence of further severe injuries and cardiac arrest. Conclusion Endovascular therapy became the treatment of choice for BTAI in Germany. Patients who have been treated by surgical means showed the highest survival rate, especially endovascular therapy showed a favorable low mortality rate.

Open Thoracic and Thoraco-abdominal Aortic Repair in Patients with Connective Tissue Disease

Retrospective cross-border, single centre study February 2000 to April 2016 72 aortic operations on 65 patients with CTD 41 male, median age 41 years [range 19–70 years] 56 patients (86%) with previous aortic repair (71 open, 4 endovascular) 33 patients (51%) operated before at the site of the procedure reported here Procedures: 8 emergency operations (11%) Aortic arch revision (n = 1; 1%) Descending thoracic aortic repair (n = 11; 15%) TAAA type I repair (n = 12; 17%), Type II repair (n = 29; 40%) Type III repair (n = 12; 17%) Type IV repair (n = 5; 7%). Ascending aorta and/or the aortic arch (n = 2; 3%) and (n = 8; 11%) 7 patients (10%) underwent staged procedures Median follow-up: 42 months (0.5–180 months)

Selective renal blood perfusion induces renal tubules injury in a porcine model

OBJECTIVEnExtracorporeal circulation is routinely used in thoracoabdominal aortic aneurysm repair to preserve blood perfusion. Despite this protective measure, acute and chronic kidney disorders can develop. Therefore, the aim of this study was to establish a new large-animal model to assess the efficacy of selective renal perfusion (SRP) with extracorporeal circulation in a setting of thoracoabdominal aortic aneurysm repair.nnnMETHODSnEighteen pigs underwent a thoracolaparotomy, during with the aorta and renal arteries were exposed. The animals were divided into three cohorts of six pigs each: cohort I--control; cohort II--thoracic aortic clamping with distal aortic perfusion (DAP) using a roller pump; and cohort III--thoracic aortic clamping with DAP plus SRP. Kidney metabolism, kidney injury, and red blood cell damage were measured by oxygen extraction ratio (O2ER), neutrophil gelatinase-associated lipocalin, a marker for acute kidney damage, and serum free hemoglobin.nnnRESULTSnWith normal mean arterial blood pressures, flow rates in the renal arteries during perfusion decreased to 75% (group II) with DAP and to 50% (group III) with SRP compared with the control animals (group I; P = .0279 for I vs II; P = .0002 for I vs III). Microcirculation, measured by microspheres, did not differ significantly among the groups. In contrast, O2ER (P = .0021 for I vs III) and neutrophil gelatinase-associated lipocalin (P = .0083 for I vs III) levels were significantly increased in group III, whereas free hemoglobin was increased in groups II and III (P = .0406 for I vs II; P = .0018 for I vs III).nnnCONCLUSIONSnSRP with a roller pump induces kidney tubule injury. Thus, distal aortic and SRP in our model does not provide adequate kidney protection. Furthermore, the perfusion system provokes red blood cell damage with increased free hemoglobin. Hence, the SRP perfusion technique should be revised and tested.

Extracorporeal circulation increases proliferation in the intestinal mucosa in a large animal model

OBJECTIVEnExtracorporeal circulation induces ischemia/reperfusion injury in the small intestinal wall. One reason for this damage is a perfusion shift from the muscular toward the mucosal layer. This study investigated the effect of this perfusion shift on the small-intestinal apoptosis and proliferation.nnnMETHODSnTwenty-eight pigs were randomly assigned to the following cohorts and underwent a thoracolaparotomy and a 1xa0hour main procedure: cohort I: control; cohort II: thoracic aortic cross-clamping (TAC) without perfusion; cohort III: TAC and distal aortic perfusion (DAP); cohort IV: TAC, DAP, and selective visceral perfusion. The main procedure was followed by 2xa0hours of reperfusion in all cohorts. Tissue samples were taken during the experiment, stained, and analyzed for apoptosis and proliferation (caspase-3, annexin-V, terminal deoxynucleotide transferase-mediated deoxy uridine triphosphate nick-end labeling, and proliferating cell nuclear antigen). Six animals died unexpectedly during the experiment and were excluded from the analysis.nnnRESULTSnExtensive tissue damage and necrosis was only found in cohort II after the main procedure. In the mucosa, the proliferation was increased in cohort III at the end of the experiment (Pxa0= .0157 cohort I vs II). In contrast, the annexin-V/proliferating cell nuclear antigen ratio was significantly higher in cohorts II and IV than in cohorts I and II at the end of the experiment (Pxa0= .0034). Furthermore, the caspase-3/annexin-V ratio was increased in all cohorts at the end of the experiment (Pxa0= .0015).nnnCONCLUSIONSnMucosal proliferation is the early repair mechanism of the limited small intestinal ischemia/reperfusion injury after DAP. Furthermore, the extensive surgical trauma shifted the mucosal apoptosis into an advanced state.

Stellenwert von prognostischen Biomarkern in der offenen und endovaskulären Aortenchirurgie

In der Humanmedizin werden arzneimittelbezogene und krankheitsbezogene Biomarkerunterschieden.Dervorliegende Artikel wird sich mit der letztgenannten Gruppe beschäftigen. Innerhalb der krankheitsbezogenen Biomarker werden prädiktive bzw. prognostische Marker, die eine drohende Erkrankung anzeigen sollen, von diagnostischen Markern für bereitsmanifesteErkrankungendifferenziert. DieÜbergänge sind hierbei teilweise fließend. Thorakoabdominelle Aortenaneurysmen sind seltene, jedoch gefürchtete Erkrankungen. Mit 10 neuen Aneurysmen auf 100.000 Personen pro Jahr sind sie darüber hinaus eine relevante Todesursache bei Menschen jenseits des 55. Lebensjahres [1, 2]. Die operative Sanierung thorakoabdomineller Aortenaneurysmen, egal ob offen chirurgisch oder durch endovaskuläre Techniken, ist mit einer hohen Rate von Komplikationen und einer relevanten Krankenhausmortalität behaftet [3, 4]. Zudem korreliert die Ausdehnung des betroffenen und zu sanierendenAortensegments mit der Wahrscheinlichkeit von Komplikationen. Trotz der endovaskulären Therapieoption sind wir weiterhin mit aus der offenen Chirurgie bekannten Komplikationen wie Nierenund Lungenversagen, sowiederspinalenIschämie konfrontiert. Hier spielen, neben dem durch den Klemmschaden resultierenden Ischämie-Reperfusionssyndrom in der offenen Aortenchirurgie, auch inflammatorische Prozesse eine Rolle, die sich z.B. durch eine starke Endothelreaktion ebenso bei endovaskulären Operationen finden lassen. Besonders das postoperative akute Nierenversagen (AKN) ist für die Gesamtmortalität nach elektiver und auch notfallmäßiger Aortenchirurgie eine entscheidende Stellgröße für das Überleben von Patienten [5]. Im klinischenAlltag ist die Diagnose des AKN an klinische Scoring-Systeme wie die Urinausscheidung und den Serum-Kreatininspiegel geknüpft, wobei die fehlende Spezifität problematisch ist [6]. In der postoperativen klinischen Routine haben neue Biomarker zur Detektion eines AKN noch keinen Einzug gefunden, was möglicherweise mit einer verzögerten Diagnosestellung und entsprechend schlechteren Verläufen postoperativ assoziiert ist. Hinsichtlich der perioperativen Inflammationsreaktion nach offener und endovaskulärer TAAA-Chirurgie existieren nur wenige publizierte Daten; Fiane und Welborn haben in ihren Studien verschiedene Inflammationsmarker nach offener TAAAChirurgie bestimmt. Hinsichtlich erhöhter TNF-αsowie Interleukin 1, 6 und 8Werte zeigte sich postoperativ eine Assoziation mit einer höheren Rate an Organkomplikationen und eine erhöhte Mortalitätsrate [7, 8]. Im Bereich der endovaskulären Aortenchirurgie existieren noch weniger entsprechende Studien [9]. Es besteht demnach Bedarf an Untersuchungen zu neuen, möglichst spezifischen Biomarkern, welche mit ausreichender Sensitivität postoperative Komplikationen erfassbar machen und dabei helfen könnten, Hochrisikopatienten zu erkennen. Im Kontrast zu den Erfahrungen im gefäßchirurgischen Bereich finden sich zum Beispiel in der Herz-ThoraxChirurgie in den letzten Jahren zunehmend randomisierte, multizentrische Kontrollstudien, welche die Wertigkeit hinsichtlich eines verbesserten Patientenüberlebens durch das konsequente Nutzen von postoperativen Biomarkern belegen sollen. Sowohl national als auch international fehlen bisher ähnliche Arbeiten im gefäßchirurgischen Bereich. Die Autoren dieses Artikels möchten daher den folgenden kurzen Exkurs in den Bereich der Biomarker für die postoperative Inflammation und das akute Nierenversagen nach offener und endovaskulärer thorakaler Aortenchirurgie dazu nutzen, eine standortübergreifende, jedoch auch interdisziplinäre wissenschaftliche Kooperation anzuregen. Zu den im Rahmen dieses Artikels beispielhaft verwendeten Biomarkern (. Abb. 1) existieren Erfahrungswerte, die durch weitere Forschungsgruppen vertieft bzw. durch weitere Marker ergänzt werden können.

Editor's Choice – Open Thoracic and Thoraco-abdominal Aortic Repair After Prior Endovascular Therapy

OBJECTIVEnThe aim was to present current results of open thoracic and thoraco-abdominal aortic repair as secondary procedure after prior endovascular therapy.nnnMETHODSnThis was a retrospective cross border single centre study. From 2006 to July 2017 45 open thoracic aortic (TAA) or thoraco-abdominal aortic aneurysm (TAAA) operations were performed on 44 patients (median age 58 [15-80] years) as secondary surgery after previous endovascular therapy comprising TEVAR (nxa0=xa038; 86%), EVAR (nxa0=xa03; 7%), fenestrated EVAR (nxa0=xa01; 2%) and TEVAR plus EVAR (nxa0=xa01; 2%). Eleven patients (25%) had had previous open aortic surgery at the secondary surgery site. Indications for TAA(A) repair were Type I endoleak (nxa0=xa010; 23%), post-dissection aneurysm progression due to persisting false lumen perfusion (nxa0=xa08; 18%), proximal/distal disease progression (nxa0=xa016; 36%), device fracture/dislocation (nxa0=xa04; 9%), infection (nxa0=xa05; 11%), and initial endograft misplacement (nxa0=xa01; 2%). The operations included descending thoracic aortic repair (nxa0=xa013, 29%), TAAA Type I (nxa0=xa04; 9%), Type II (nxa0=xa05; 11%), Type III (nxa0=xa013; 29%), Type IV (nxa0=xa07; 16%), and Type V repair (nxa0=xa03; 7%) with simultaneous arch repair in 18% (nxa0=xa08). The median time to secondary surgery was 36 (2-168) months. The median follow up was 39 (3-118) months.nnnRESULTSnIn hospital mortality was 20% (nxa0=xa09) due to intra-operative aneurysm rupture, pneumonia induced sepsis, hemorrhagic cerebellar infarction, mesenteric ischaemia, broncho-esophageal fistula, and multiorgan failure (1/9) as well as haemorrhage (3/9). Estimated survival was 73% at 1 year and 71% overall. The most frequent complications were pneumonia (nxa0=xa019; 43%), bleeding requiring revision (nxa0=xa011; 25%) and sepsis (nxa0=xa014; 32%). Transient dialysis was required in 32% (nxa0=xa014), permanent dialysis in 6% (nxa0=xa02). Permanent spinal cord deficit (paraparesis) occurred in 6% (nxa0=xa02). Estimated freedom from aortic re-intervention was 86%.nnnCONCLUSIONnOpen TAA(A) repair as a secondary procedure after previous endovascular aortic therapy is an important treatment option even in the endovascular era. It represents a durable treatment that can produce respectable outcomes. Yet the peri-operative morbidity and mortality are relevant and a specialised team and infrastructure are mandatory for these complex procedures. Therefore, centralisation is required.