Hilmar Kühl

Vascular Access Site Complications after Percutaneous Transfemoral Aortic Valve Implantation

Background and Purpose:Transcatheter aortic valve implantation (TAVI) is a rapidly emerging treatment option for patients with aortic valve stenosis and high surgical risk. Different access routes have been proposed for TAVI including transapical, transsubclavian and transfemoral, with percutaneous transfemoral being the preferred because least invasive and nonsurgical. However, vascular access site complications due to the large-bore delivery catheters remain an important clinical issue, particularly with respect to the elderly patient collective typically considered for TAVI. In the study, the authors analyzed their 4-year TAVI experience with respect to vascular complications and their management in patients undergoing completely percutaneous transfemoral TAVI procedures.Patients and Methods:Since 2006, TAVI was performed in 101 consecutive patients at the West German Heart Center Essen. 33 patients underwent transapical TAVI, eight patients transfemoral TAVI with surgical access or closure, and 60 patients percutaneous transfemoral TAVI using two commercially available prosthetic valve devices.Results:Completely percutaneous TAVI was technically successful in all but one patient with malpositioning in the aortic arch during valve retrieval. There was no intraprocedural death and 30-day mortality was 12% (7/60). Vascular access site complications occurred in 19 patients (32%), necessitating surgical repair in six of them (10%). Complications included retroperitoneal hematoma (n = 2), iliac or femoral artery dissection (n = 10), (pseudo)aneurysm formation (n = 3), and closure device-induced vessel stenosis/ occlusion (n = 6). Of these, 13 cases could be managed either conservatively (n = 5) or by contralateral endovascular treatment (n = 8).Conclusion:Completely percutaneous TAVI has a high acute success rate with low intraprocedural and 30-day mortality. The patient collective appears to be prone to vascular complications which remain an important limitation of this novel technique. Although conservative or endovascular management is possible in the majority of cases, further technological developments are obliged to reduce the vascular complication rate.ZusammenfassungHintergrund und Fragestellung:Die katheterbasierte Aortenklappenimplantation ist eine neue, in der klinischen Routine bereits breit angewandte Therapieoption für Hochrisikopatienten mit kalzifizierter Aortenklappenstenose. Während in der Anfangsphase noch eine chirurgische Freilegung der arteriellen Zugangsgefäße und damit verbunden eine Vollnarkose nötig waren, ist die Durchführung heute in einer rein perkutanen Technik und somit sogar unter Analgosedierung möglich. Aufgrund der großen Kaliber der zur Einführung und zum Vorschieben der Prothese benötigten Schleusen und Katheter birgt diese Prozedur jedoch das Risiko einer Verletzung der arteriellen Zugangsgefäße, insbesondere da diese bei den betroffenen, älteren Patienten häufig atherosklerotische Veränderungen aufweisen. Die vorliegende Untersuchung gibt einen Überblick über die vaskulären Komplikationen und mögliche Managementstrategien an einem Kollektiv von 60 konsekutiven Patienten, bei denen in rein perkutaner Technik eine transfemorale Aortenklappenimplantation durchgeführt wurde.Patienten und Methodik:Seit 2006 wurde am Westdeutschen Herzzentrum Essen bei insgesamt 101 konsekutiven Patienten eine kathetergesteuerte Aortenklappenimplantation durchgeführt, bei 33 Patienten über den transapikalen, bei 68 Patienten über den transfemoralen Zugang. Während bei den initialen acht in transfemoraler Technik behandelten Patienten noch eine chirurgische Freilegung und/oder ein chirurgischer Verschluss der Zugangsgefäße durchgeführt wurde, erfolgte die Implantation der ballonexpandierbaren Edwards-Sapien- (n = 41) und der selbstexpandierbaren CoreValve-Prothese (n = 19) bei de hemofolgenden 60 Patienten in rein perkutaner Technik unter Verwendung von Nahtverschlusssystemen.Ergebnisse:Bis auf eine Fehlpositionierung im Aortenbogen konnten alle Aortenklappenprothesen erfolgreich in rein perkutaner Technik und ohne intraprozeduralen Todesfall implantiert werden. Die 30-Tage-Mortalität betrug 12%. Postinterventionell zeigte sich eine signifikante Verbesserung der Hämodynamik mit Abfall des mittleren transaortalen Druckgradienten von 52 ± 18 auf 13 ± 6 mmHg und einer Zunahme der Klappenöffnungsfläche von 0,6 ± 0,2 auf 1,5 ± 0,3 cm2. Die Rate an vaskulären Komplikationen betrug 32% (19 von 60 Patienten). Die Komplikationen beinhalteten zwei retroperitoneale Hämatome, zehn Dissektionen der Femoral- und Iliakal gefäße, drei Aneurysmabildungen und sechs ver schluss systeminduzierte Komplikationen. In fünf Fällen erfolgte eine konservative Therapie, bei acht Patienten konnte eine katheterinterventionelle Behandlung durchgeführt werden. Eine operative Sanierung war bei sechs Patienten (10%) nötig.Schlussfolgerung:Die transfemorale Aortenklappenimplantation kann heutzutage in rein perkutaner Technik mit einer hohen Erfolgsrate, geringer Mortalität und guten hämodynamischen und klinischen Ergebnissen durchgeführt werden. Vaskuläre Komplikationen sind jedoch noch häufig und stellen eine wichtige Limitation dieser neuen Technik dar. Obwohl ein konservatives oder interventionelles Management dieser Komplikationen in der Regel möglich ist, müssen zukünftige Weiterentwicklungen in besonderem Maße auch auf eine Reduktion der vaskulären Komplikationsrate gerichtet sein.

Aortoesophageal fistula after thoracic aortic stent-graft placement: a rare but catastrophic complication of a novel emerging technique.

OBJECTIVES Our goal was to report characteristics and outcomes of 6 patients with aortoesophageal fistula (AEF) after thoracic endovascular aortic repair (TEVAR). BACKGROUND Neurologic events are severe complications of TEVAR. With growing experience of TEVAR, other yet unexpected devastating complications have emerged. METHODS Between July 1999 and August 2008, 268 patients underwent TEVAR for various thoracic aortic diseases at our institution. RESULTS Six of 268 patients (age 49 to 77 years, 50% female patients) developed AEF (incidence 1.9%) within 1 to 16 months after the procedure. Indications for TEVAR were acute aortic dissection (n = 3), chronic aortic dissection (n = 1), and thoracic aortic aneurysm (n = 2). Four patients presented with sudden massive hematemesis whereas 2 patients were readmitted for new-onset fever and elevated markers of inflammation that preceded hematemesis. Esophago-gastro-duodenoscopy identified deep esophageal ulcerations at the level of the implanted aortic stent-graft in 4 patients, but only mild erosive lesions within the proximal esophagus without signs of active bleeding in the remaining 2 patients. Surgical repair was performed in only 1 patient and declined in the remaining because of comorbidities and multiorgan system failure. Despite this, all patients died due to fatal rebleeding (n = 4) or mediastinitis (n = 2). CONCLUSIONS AEF is a rare and unusual complication of TEVAR that occurs relatively early after the procedure and is almost invariably fatal. New-onset fever with elevated inflammatory markers or hematemesis should heighten clinical suspicion of AEF in TEVAR patients and prompt computed tomography or esophago-gastro-duodenoscopy in the hope of detecting, triaging, and treating this early to improve the otherwise dismal outcomes of these patients.

Aortic Remodeling in Type B Aortic Dissection: Effects of Endovascular Stent-Graft Repair and Medical Treatment on True and False Lumen Volumes:

Purpose: To analyze aortic remodeling processes in terms of true (TL) and false lumen (FL) volumes in patients with type B aortic dissection undergoing thoracic endovascular aortic repair (TEVAR) versus patients treated medically. Methods: Serial contrast-enhanced computed tomography (CT) scans of 27 type B dissection patients (24 men; mean age 60±13 years) who underwent TEVAR (n=17) or medical therapy only (n=10) were analyzed. TL and FL volumes over the entire descending aorta at baseline and at follow-up were quantified by 3-dimensional reconstruction. Results: Follow-up in the 27 patients was a mean 14±6 months. TEVAR resulted in a continued gain in total TL volume (132±56 mL at baseline, 164±51 mL early after TEVAR, and 220±68 mL at follow-up, p<0.001), whereas TL volume was almost unchanged in the medical therapy group (113±34 to 120±41 mL, p=0.195). Total FL volume decreased significantly in TEVAR patients during follow-up (257±147 mL at baseline to 178±140 mL, p<0.001), whereas there was no significant change in FL volume in the medical therapy patients. The increase of TL and the decrease of FL volume in the TEVAR group were mainly observed in the descending thoracic aorta. Conclusion: TEVAR for type B aortic dissection results in a significant increase in TL and a decrease in FL volumes, not only acutely but also over time due to continued remodeling processes primarily in the thoracic aorta, with little impact on abdominal aortic volumes. Our data provide insight into the mechanism of a potential therapeutic benefit of TEVAR over medical therapy in type B dissection, which remains to be confirmed in a randomized clinical trial.

Respiration artifacts in whole-body 18F-FDG PET/CT studies with combined PET/CT tomographs employing spiral CT technology with 1 to 16 detector rows

PurposeCo-registration accuracy in combined whole-body (WB) PET/CT imaging is impaired by respiration-induced mismatches between the CT and the PET. Furthermore, PET/CT misregistration may bias the PET tracer distribution following CT-based attenuation correction (CT-AC). With the introduction of multi-row CT technology of up to 16 detector rows into PET/CT designs, we investigated the incidence of respiration artifacts in WB PET/CT examinations of patients who were unable to follow any breath-hold instructions.MethodsA total of 80 WB studies from six international sites operating PET/CT tomographs with 1-, 2-, 4-, 6-, 8-, and 16-row spiral CT were included. PET/CT examinations were acquired with the patients breathing normally during both the CT and the PET scan, and CT-AC was performed routinely. All studies were anonymized and reviewed independently by three radiologists and three nuclear medicine specialists. We report the frequency and severity of artifacts on CT and PET for the thorax and the abdomen.ResultsIn WB PET/CT imaging of normally breathing patients, significant gains in diagnostic image quality can be expected from employing CT technology with six or more detector rows. In our study, fewer PET images appear distorted than corresponding CT images, which is due to the limited propagation of only mild CT image artifacts after the resampling of the CT-based attenuation map during CT-AC.ConclusionIn whole-body PET/CT imaging of normally breathing patients, respiration-induced artifacts are reduced in both magnitude and prominence for PET/CT systems employing CT components of six or more detector rows.

Diffusion-weighted imaging as part of hybrid PET/MRI protocols for whole-body cancer staging: does it benefit lesion detection?

PURPOSE Positron emission tomography/magnetic resonance imaging (PET/MRI) requires efficient scan protocols for whole-body cancer staging. The aim of this study was to evaluate if the application of diffusion-weighted MR imaging (DWI) results in a diagnostic benefit for lesion detection in oncologic patients if added to a whole-body [18F]-fluorodesoxyglucose ([18F]-FDG) PET/MRI protocol. METHODS 25 consecutive oncologic patients (16 men, 9 women; age 57 ± 12 years) prospectively underwent whole-body [18F]-FDG-PET/MRI including DWI on a hybrid PET/MRI scanner. A team of two readers assessed [18F]-FDG PET/MRI without DWI for primary tumors and metastases. In a second session, now considering DWI, readers reassessed [18F]-FDG PET/MRI accordingly. Additionally, the lesion-to-background contrast on [18F]-FDG PET and DWI was rated qualitatively (0, invisible; 1, low; 2, intermediate; 3, high). Wilcoxons signed-rank test was performed to test for differences in the lesion-to-background contrast. RESULTS 49 lesions were detected in 16 patients (5 primaries, 44 metastases). All 49 lesions were concordantly detected by [18F]-FDG PET/MRI alone and [18F]-FDG PET/MRI with DWI. The lesion-to-background contrast on DWI compared to [18F]-FDG PET was rated lower in 22 (44.9%) of 49 detected lesions resulting in a significantly higher lesion-to-background contrast on [18F]-FDG PET compared to DWI (P=0.001). CONCLUSIONS DWI as part of whole-body [18F]-FDG PET/MRI does not benefit lesion detection. Given the necessity to optimize imaging protocols with regard to patient comfort and efficacy, DWI has to be questioned as a standard tool for whole-body staging in oncologic PET/MRI.

Correlation of the Apparent Diffusion Coefficient (ADC) with the Standardized Uptake Value (SUV) in Hybrid 18F-FDG PET/MRI in Non-Small Cell Lung Cancer (NSCLC) Lesions: Initial Results

PURPOSE To compare the apparent diffusion coefficient (ADC) in non-small cell lung cancer lesions with standardized uptake values (SUV) derived from combined 18F-fluoro-deoxy-glucose-positron emission tomography/magnetic resonance imaging (FDG-PET/MRI) and those derived from FDG-PET/CT. MATERIALS AND METHODS In 18 consecutive patients with histologically proven NSCLC (17 men, 1 woman; mean age, 61 ± 12 years), whole-body FDG-PET/MRI was performed after whole-body FDG-PET/CT. Regions of interest (ROI) encompassing the entire primary tumor were drawn into FDG-PET/CT and FDG-PET/MR images to determine the maximum and mean standardized uptake value (SUVmax; SUVmean) and into ADC parameter maps to assess mean ADC values. Pearsons correlation coefficients were calculated to compare SUV and ADC values. RESULTS The SUVmax of NSCLC was 12.3 ± 4.8 [mean ±SD], and the SUVmean was 7.2 ± 2.8 as assessed by FDG-PET/MRI. The SUVmax and SUVmean derived from FDG-PET/CT and FDG-PET/MRI correlated well (R = 0.93; p < 0.001 and R = 0.92; p < 0.001, respectively). The ADCmean of the pulmonary tumors was 187.9 ± 88.8 × 10-5 mm²/s [mean ± SD]. The ADCmean exhibited a significant inverse correlation with the SUVmax (R = -0.72; p < 0.001) as well as with the SUVmean assessed by FDG-PET/MRI (R = -0.71; p < 0.001). CONCLUSION This simultaneous PET/MRI study corroborates the assumed significant inverse correlation between increased metabolic activity on FDG-PET and restricted diffusion on DWI in NSCLC.Citation Format:

Malignant Pheochromocytoma Imaging with [124I]mIBG PET/MR

Pheochromocytoma localized in the adrenal medulla (in 85%) or in the thoracic/abdominal sympathetic trunk (paraganglioma) has malignant potential in about 10% of cases. Metaiodobenzylguanidine (mIBG) can be labeled with 123-iodine (for scintigraphy), 131-iodine (basically for therapy), or 124-iodine [excellent positron emission tomography (PET) imaging and tumor dosimetry based on high spatial resolution] and has high sensitivity for the diagnosis of primary/metastatic pheochromocytoma (1–3). Thiscasereportsontheworldwidefirst [I]-mIBG-PET/ magnetic resonance imaging (MRI) performed with an integrated PET/MR (Biograph mMR; Siemens Healthcare, Erlangen, Germany) in a malignant pheochromocytoma. The addition of MRI to mIBG-PET is promising as it improves tumor delineation because of the high soft tissue contrast in MRI that is especially relevant in pretherapeutic dosimetry. Compared with conventional [I]mIBG scintigraphy, [I]mIBG-PET provides high-resolution images. A 24-yr-old woman suffering from progressive malignant pheochromocytoma (primary right adrenal) underwent dosimetry with [I]mIBG PET/computed tomography (CT) (50 MBq) for treatment planning before therapy with [I]mIBG. An additional whole-body PET/ MRI (48 h after [I]mIBG administration) was performed with the following examination parameters (entire acquisition time, 40 min): four bed positions (head to upper thigh); PET, 8-min list mode per bed position; MRI, DIXON (T1-weighted sequences in-/opposed phases) for acquiring the -map for attenuation correction, simultaneous with PET non-contrast-enhanced coronal T1, transversal fat-saturated T2, and diffusionweighted imaging non-simultaneous followed by coronal and axial fat-saturated T1 after administration of gadolinium-based contrast agent. The PET/MRI (Fig. 1A, PET maximum intensity projection (MIP); B, fused PET/MRI coronal T1; C, fused PET/CT coronal) revealed local tumor recurrence (right adrenal bed) and multiple metastases (liver, lymph nodes, abdominal muscles, peritoneal) with intense tracer uptake, hyperintense signal on T2, hypointense on nonen-

Aortic remodelling in aortic dissection after frozen elephant trunk

OBJECTIVES Frozen elephant trunk (FET) can be used for continuous downstream aorta treatment in acute aortic dissection (AAD) and chronic aortic dissection (CAD). The study reports the changes in the lumen volumes along the downstream aorta towards remodelling. METHODS In 70 patients (22 CAD, 48 AAD), pre-, postoperative and at least the 1-year follow-up aortic imaging was available. Volume changes of aortic lumen (AL) and true lumen (TL) between examinations along the stent graft aortic segment (A), downstream to coeliac trunk (B) and distally to bifurcation (C) were used for quantification. TL increase >10% with stable AL or AL decrease >10% with stable TL were classified as positive, changes within a 10% threshold as stable, and all other changes as negative remodelling. RESULTS In AAD, positive or stable remodelling occurred in A (90%), B (65%), C (58%) within 1 year, thereafter in 26 patients (follow-up: 47 ± 21 months) in A (92%), B (65%), C (62%). Negative remodelling in ≥2 segments was found in 5/26 (19%) patients. In CAD, positive or stable remodelling occurred in A (100%), B (86%), C (77%) within 1 year, thereafter in 16 patients (follow-up: 46 ± 20 months) in A (75%), B (44%), C (38%). Negative remodelling in ≥2 segments was found in 7/16 (43%) patients, 5 underwent reintervention, and stabilized thereafter. CONCLUSIONS FET facilitates positive remodelling in AAD and CAD down to stent graft level. Distally, 20% AAD and 40% CAD patients remain at risk for secondary reintervention, and can be identified by negative remodelling in ≥2 segments in the follow-up examinations.

Endovascular stent-graft placement for acute and contained rupture of the descending thoracic aorta

Objectives: To identify determinants of postinterventional death after endovascular stent‐graft placement for acute rupture of the descending thoracic aorta, an emerging therapeutic modality for this highly life‐threatening condition. Methods: Between July 1999 and November 2004, 17 patients (14 males; mean age, 65 ± 16 (25–83) years) underwent stent‐graft repair of the descending thoracic aorta for acute rupture from a thoracic aneurysm (TAA, n = 6), acute aortic dissection (AAD, n = 6), penetrating aortic ulcer (PAU, n = 3), or blunt chest trauma (n = 2). Immediate, 30‐day, 1‐year, and 3‐year mortality was assessed. Twenty‐one clinical and procedural variables were evaluated in a post‐hoc analysis regarding their influence on mortality. Of these, four preprocedural factors with the greatest impact were used to construct a rupture score with a scale from 0 (no adverse prognostic factors present) to 4 (all four adverse factors present). Results: Stent‐graft placement was technically feasible in all patients. Complete exclusion of the ruptured aortic pathology could be achieved in only 11 (65%) patients, despite implantation of 1.6 ± 0.9 stent‐grafts per patient, with a median length of 130 mm. There was one procedure‐related early complication (bleeding at the access site). One patient died immediately following the procedure because of progressive mediastinal hematoma, although the rupture site was effectively sealed. Overall survival rates were (76.5 ± 10.3)% at 30 days and (52.9 ± 12.1)% at 1 year and remained at (52.9 ± 12.1)% at 3 years. The four most important preprocedural denominators of death were (1) TAA or AAD as the underlying etiology of aortic rupture (P = 0.024), (2) maximum aortic diameter >5 cm (P = 0.024), (3) presence of mediastinal hematoma (P = 0.056), and (4) an estimated lesion length requiring >1 stent‐graft to be covered (P = 0.009). Furthermore, residual leakage at the conclusion of the procedure (P = 0.009), postprocedural need for dialysis (P = 0.004), and prolonged ventilation (P = 0.043) were significantly associated with postprocedural death. Using a threshold of ≥3, the rupture score constructed on the basis of the four preprocedural denominators of death was found to be well suited to discriminate postprocedural death (1‐year survival: (20.0 ± 12.7)% in patients with a rupture score ≥3 vs. 100% in patients with a rupture score <3, P = 0.001). Conclusion: Endovascular stent‐graft placement in patients with acute aortic rupture was technically feasible, albeit still associated with high mortality. A simple risk score constructed in retrospect, on the basis of preprocedural prognostic factors, appeared to provide a useful separation of candidates who are likely to benefit from a straightforward endovascular procedure and should be tested prospectively in future studies.

The Role of Imaging in Percutaneous Mitral Valve Repair

Percutaneous, transcatheter mitral valve repair has recently been introduced and various strategies – loosely based on surgical techniques – are currently under clinical and preclinical evaluation. Since percutaneous mitral valve repair techniques are rather specific regarding both the underlying cause of mitral regurgitation and patient anatomy, careful preinterventional imaging using various techniques is required for appropriate patient selection and essential for procedural success. While echocardiography is the dominant imaging modality for determination of mitral regurgitation severity and etiology, other imaging modalities like contrast-enhanced multidetector computed tomography, magnetic resonance imaging, and fluoroscopy/angiography may play an important role in the preinterventional evaluation process. In addition, imaging is of utmost importance for procedural guidance and the combined use of various imaging modalities, commonly fluoroscopy and echocardiography, is needed in the catheterization laboratory to ensure safety and efficacy of mitral valve repair procedures. Finally, imaging is essential for an adequate patient follow-up aiming to control stable device positioning, persistency of the geometric modifications induced, and continuous reduction of mitral regurgitation. This review highlights the role of various imaging techniques during preinterventional evaluation, procedural guidance and follow-up in the setting of percutaneous mitral valve repair with special focus on edge-to-edge leaflet repair and indirect annuloplasty via the coronary sinus as the best-studied approaches to date.ZusammenfassungAktuell befinden sich verschiedene, letztlich auf chirurgischen Techniken basierende, katheterinterventionelle Verfahren zur Therapie einer Mitralklappeninsuffizienz in klinischer und präklinischer Erprobung. Diese Verfahren sind im Vergleich zur Chirurgie jedoch sehr spezifisch im Hinblick auf den zugrundeliegenden Pathomechanismus und die anatomischen Voraussetzungen, so dass eine eingehende präinterventionelle Bildgebung für die Auswahl geeigneter Kandidaten nötig ist. Die Echokardiographie ist das Mittel der Wahl zur Beurteilung des Schweregrads und der Ätiologie einer Mitralklappeninsuffizienz und somit essentieller Bestandteil der präinterventionellen Diagnostik. Computertomographie, Magnetresonanztomographie, Fluoroskopie und Angiographie sind weitere Bildgebungsmodalitäten, die im Rahmen der präinterventionellen Evaluation vor perkutaner Mitralklappenintervention eine Rolle spielen. Die periinterventionelle Bildgebung erfolgt mittels Kombination mehrerer Bildgebungsmodalitäten, in der Regel Durchleuchtung und Echokardiographie, um einen sicheren und erfolgreichen Eingriff zu gewährleisten. Auch im Rahmen der Patientennachsorge ist eine adäquate Bildgebung zur Kontrolle der Lage des implantierten Systems, der geometrischen Veränderungen des Mitralklappenapparats und der Mitralinsuffizienz nötig. Auch hier ist die Echokardiographie das Mittel der Wahl, ergänzt durch konventionelle Röntgenaufnahmen des Thorax in zwei Ebenen und ggf. Durchleuchtung bei Verdacht auf eine Fehlfunktion des Systems. Der vorliegende Artikel gibt einen Überblick über die Rolle der verschiedenen Bildgebungsmodalitäten bei perkutanen Mitralklappeninterventionen während der präinterventionellen Diagnostik, der periinterventionellen Führung und der Patientennachsorge mit speziellem Fokus auf das sog. Mitralklappenclipping und die indirekte Mitralklappenanuloplastie über den Koronarsinus, die zurzeit die am besten untersuchten Systeme sind.