Idiopathic and hereditary haemorrhagic telangiectasia associated pulmonary arteriovenous malformations: comparison of clinical and radiographic characteristics.

AIM: To determine whether there are differences between idiopathic and hereditary haemorrhagic telangiectasia (HHT) associated pulmonary arteriovenous malformations (PAVMs) (HHT-PAVM) regarding clinical and radiographic characteristics, and the results of embolotherapy. MATERIALS AND METHODS: A retrospective analysis was undertaken of all adult and adolescent patients who were diagnosed with a PAVM on chest computed tomography (CT) from January 2006 until August 2019. RESULTS: In total, 41 patients with idiopathic PAVMs and 194 patients with genetically confirmed HHT and PAVMs were included. Idiopathic PAVMs were more frequently observed in female patients, were more solitary, and predominantly located in the lower lobes. The diameter of the feeding artery and type of PAVM (simple versus complex) were similar. Embolotherapy results were comparable between both groups with similar re-embolisation rates. CONCLUSIONS: PAVMs of idiopathic origin are predominantly found in women, more frequently located in the lower lobes, and solitary compared to HHT-PAVMs; however, the outcome of treatment is the same, suggesting that treatment and follow-up should be similar in both groups.

A Metamodeling Approach for Instant Severity Assessment and Uncertainty Quantification of Iliac Artery Stenoses.

Two-dimensional (2D) or three-dimensional (3D) models of blood flow in stenosed arteries can be used to patient-specifically predict outcome metrics, thereby supporting the physicians in decision making processes. However, these models are time consuming which limits the feasibility of output uncertainty quantification (UQ). Accurate surrogates (metamodels) might be the solution. In this study, we aim to demonstrate the feasibility of a generalized polynomial chaos expansion-based metamodel to predict a clinically relevant output metric and to quantify the output uncertainty. As an example, a metamodel was constructed from a recently developed 2D model that was shown to be able to estimate translesional pressure drops in iliac artery stenoses (-0.9 ± 12.7 mmHg, R2 = 0.81). The metamodel was constructed from a virtual database using the adaptive generalized polynomial chaos expansion (agPCE) method. The constructed metamodel was then applied to 25 stenosed iliac arteries to predict the patient-specific pressure drop and to perform UQ. Comparing predicted pressure drops of the metamodel and in vivo measured pressure drops, the mean bias (-0.2 ± 13.7 mmHg) and the coefficient of determination (R2 = 0.80) were as good as of the original 2D computational fluid dynamics (CFD) model. UQ results of the 2D and metamodel were comparable. Estimation of the uncertainty interval using the original 2D model took 14 days, whereas the result of the metamodel was instantly available. In conclusion, it is feasible to quantify the uncertainty of the output metric and perform sensitivity analysis (SA) instantly using a metamodel. Future studies should investigate the possibility to construct a metamodel of more complex problems.

Safety and efficacy of balloon pulmonary angioplasty in chronic thromboembolic pulmonary hypertension in the Netherlands.

BACKGROUND: Balloon pulmonary angioplasty (BPA) is an emerging treatment in patients with chronic thromboembolic pulmonary hypertension (CTEPH) and chronic thromboembolic disease (CTED). We describe the first safety and efficacy results of BPA in the Netherlands. METHODS: We selected all consecutive patients with inoperable CTEPH and CTED accepted for BPA treatment who had a six-month follow-up in the St. Antonius Hospital in Nieuwegein and the Amsterdam University Medical Center (UMC) in Amsterdam. Functional class (FC), N­terminal pro-brain natriuretic peptide (NT-proBNP), 6­minute walking test distance (6MWD) and right-sided heart catheterisation were performed at baseline and six months after last BPA. Complications for each BPA procedure were noted. RESULTS: A hundred and seventy-two BPA procedures were performed in 38 patients (61% female, mean age 65 ± 15 years). Significant improvements six months after BPA treatment were observed for functional class (63% FC I/II to 90% FC I/II, p = 0.014), mean pulmonary artery pressure (-8.9 mm Hg, p = 0.0001), pulmonary vascular resistance (-2.8 Woods Units (WU), p = 0.0001), right atrial pressure (-2.0 mm Hg, p = 0.006), stroke volume index (+5.7 ml/m2, p = 0.009) and 6MWD (+48m, p = 0.007). Non-severe complications occurred in 20 (12%) procedures. CONCLUSIONS: BPA performed in a CTEPH expert centre is an effective and safe treatment in patients with inoperable CTEPH.

A geometry-based model for non-invasive estimation of pressure gradients over iliac artery stenoses.

The aim of this study was to develop and verify a model that provides an accurate estimation of the trans-lesion hyperemic pressure gradient in iliac artery stenoses in seconds by only using patient-specific geometric properties obtained from 3-dimensional rotational angiography (3DRA). Twenty-one patients with symptomatic peripheral arterial disease (PAD), iliac artery stenoses and an ultrasound based peak systolic velocity ratio between 2.5 and 5.0 underwent 3DRA and intra-arterial pressure measurements under hyperemic conditions. For each lesion, geometric properties were extracted from the 3DRA images using quantitative vascular analysis software. Hyperemic blood flow was estimated based on stenosis geometry using an empirical relation. The geometrical properties and hyperemic flow were used to estimate the pressure gradient by means of the geometry-based model. The predicted pressure gradients were compared with in vivo measured intra-arterial pressure measurements performed under hyperemic conditions. The developed geometry-based model showed good agreement with the measured hyperemic pressure gradients resulting in a concordance correlation coefficient of 0.86. The mean bias ±â€¯2SD between the geometry-based model and in vivo measurements was comparable to results found by evaluating the actual computational fluid dynamics model (-1.0 ±â€¯14.7 mmHg vs -0.9 ±â€¯12.7 mmHg). The developed model estimates the trans-lesional pressure gradient in seconds without the need for an additional computational fluid dynamics software package. The results justify further study to assess the potential use of a geometry-based model approach to estimate pressure gradient on non-invasive CTA or MRA, thereby reducing the need for diagnostic angiography in patients suffering from PAD.

Monitoring of Foot Oxygenation with Near-infrared Spectroscopy in Patients with Critical Limb Ischemia Undergoing Percutaneous Transluminal Angioplasty: A Pilot Study.

OBJECTIVE: Near-infrared spectroscopy (NIRS) non-invasively determines tissue oxygen saturation (Sto2) in muscle tissue. Its application to monitor real time hemodynamic changes during percutaneous transluminal angioplasty (PTA) and Sto2 changes in feet 4 weeks after PTA was evaluated. METHODS: This study included 14 patients with critical limb ischemia (CLI, six patients Rutherford classification Stage IV, two patients Stage V, and six patients Stage VI). In patients with arterial ulcers, NIRS optodes were placed near the ulcer of the diseased foot (Optode 1), and at the same spot at the contralateral foot (Optode 2). In patients without arterial ulcers, Optode 1 was placed on the dorsum of the diseased foot, and Optode 2 was placed on the dorsum of the contralateral foot. Single Sto2 values, ankle brachial indices, and toe brachial indices were obtained at rest before the start of endovascular revascularization and 4 weeks after treatment. During the endovascular procedure, continuous Sto2 measurements were recorded throughout the intervention. Completion angiograms were used to evaluate the success of intervention. RESULTS: Patients underwent treatment of the superficial femoral artery (79%), popliteal artery (21%), and below the knee arteries (43%). In 13 of the 14 patients, completion angiograms showed successful treatment of target lesions. Ankle brachial indices and toe brachial indices significantly increased 4 weeks after treatment (both p < .01). Single Sto2 values of Optode 1 also significantly increased four weeks after treatment (p < .01). In contrast, single Sto2 values of Optode 2 did not (p = .73). During the endovascular procedure, continuous Sto2 measurements of Optode 1 and 2 did not increase (p = .80, and p = .61, respectively). CONCLUSIONS: NIRS monitoring of foot oxygenation in patients undergoing endovascular revascularization is safe and feasible. NIRS is a promising non-invasive technique to monitor hemodynamic changes in the feet of CLI patients after endovascular treatment using single Sto2 values.

Changes in Aortoiliac Anatomy After Elective Treatment of Infrarenal Abdominal Aortic Aneurysms with a Sac Anchoring Endoprosthesis.

OBJECTIVE: Endovascular aortic sealing (EVAS) with the Nellix endosystem (Endologix, Irvine, CA, USA) is a new concept to treat infrarenal abdominal aortic aneurysms (AAAs). By sealing the aneurysm, potential endoleaks may be avoided. Early results of EVAS are good, but no data have been published regarding peri-procedural changes in aortoiliac anatomy. In this study, 27 consecutive patients who underwent elective EVAS repair of an AAA were reviewed. METHOD: Specific AAA (diameter, length from renal arteries to aortic bifurcation, supra- and infrarenal neck angulation, AAA volume, thrombus volume, and flow lumen volume), and iliac artery characteristics (length, angulation, location of most severe angulation with reference to the origin of the common iliac artery) were determined from pre- and post-procedural reconstructed computed tomography angiograms. RESULTS: No type I or II endoleaks were seen at 30 day follow up. Total AAA volume, suprarenal and infrarenal angulation, as well as aortic neck diameter did not change significantly post-EVAS. AAA flow lumen increased significantly (mean difference -4.4 mL, 95% CI 2.0 to -8.6 mL) and AAA thrombus volume decreased (mean difference 3.2 mL, 95% CI 2.0 to -1.1 mL). AAA length (125.7 mm vs. 123.1 mm), left common iliac artery length (57.6 mm vs. 55.3 mm), and right and left maximum iliac artery angulation (right 37.4° vs. 32.2°; left: 43.9° vs. 38.4°) were reduced significantly and the location of maximum angulation was further from the iliac artery origin post-EVAS, suggesting slight straightening of the aortoiliac anatomy. CONCLUSION: Most aortoiliac anatomic characteristics remained unchanged post-EVAS. Filling of the endobags to a pressure of 180 mmHg may lead to lost thrombus volume in some patients, probably because liquid is squeezed into lumbar or the inferior mesenteric artery. The absolute differences in pre- and post-EVAS aortoiliac lengths were small, so pre-operative sizing is accurate for determining stent length.

Aortic Curvature Instead of Angulation Allows Improved Estimation of the True Aorto-iliac Trajectory.

OBJECTIVE: Supra- and infrarenal aortic neck angulation have been associated with complications after endovascular aortic aneurysm repair. However, a uniform angulation measurement method is lacking and the concept of angulation suggests a triangular oversimplification of the aortic anatomy. (Semi-)automated calculation of curvature along the center luminal line describes the actual trajectory of the aorta. This study proposes a methodology for calculating aortic (neck) curvature and suggests an additional method based on available tools in current workstations: curvature by digital calipers (CDC). METHODS: Proprietary custom software was developed for automatic calculation of the severity and location of the largest supra- and infrarenal curvature over the center luminal line. Twenty-four patients with severe supra- or infrarenal angulations (≥45°) and 11 patients with small to moderate angulations (<45°) were included. Both CDC and angulation were measured by two independent observers on the pre- and postoperative computed tomographic angiography scans. The relationships between actual curvature and CDC and angulation were visualized and tested with Pearson's correlation coefficient. The CDC was also fully automatically calculated with proprietary custom software. The difference between manual and automatic determination of CDC was tested with a paired Student t test. A p-value was considered significant when two-tailed α < .05. RESULTS: The correlation between actual curvature and manual CDC is strong (.586-.962) and even stronger for automatic CDC (.865-.961). The correlation between actual curvature and angulation is much lower (.410-.737). Flow direction angulation values overestimate CDC measurements by 60%, with larger variance. No significant difference was found in automatically calculated CDC values and manually measured CDC values. CONCLUSION: Curvature calculation of the aortic neck improves determination of the true aortic trajectory. Automatic calculation of the actual curvature is preferable, but measurement or calculation of the curvature by digital calipers is a valid alternative if actual curvature is not at hand.

Results of reinterventions for failed endovascular aortic repair: a single-center experience.

AIM: The aim of this paper was to review technical success and clinical outcome of reinterventions to treat complications after endovascular abdominal aortic aneurysm (AAA) repair (EVAR) in a tertiary vascular center. METHODS: The study enrolled 107 patients treated for post-EVAR complications between January 2005 and March 2014. Details of reinterventions, technical success, and midterm clinical outcome were analyzed for reinterventions. Radiologic follow-up after reinterventions was performed by computed tomography scans and duplex ultrasonography. RESULTS: Indications for reinterventions in the 107 patients were predominantly endoleaks type Ia, Ib, II, and III (55.1%). Endograft obstructions were observed in 39 patients (36.4%). The initial technical success rate for the 107 reinterventions was 93.5% (N.=100). Median follow-up postreintervention was 20 months (range, 1-107 months). During follow-up, 34 of 107 patients (31.8%) needed at least one renewed reintervention. Kaplan-Meier analysis of overall survival after the primary reinterventions was 85% at 1 year, and 78% at 3 years of follow-up. AAA/EVAR-associated mortality was 4% at 3 years. Kaplan-Meier survival estimation of freedom of recurrence was 88% at 1 year post-reintervention and 78% at 3 years. Renewed reintervention-free survival dropped to 78% at 1 year and 58% at 3 years. CONCLUSION: In this series of patients, the technical success rate of reinterventions to treat post-EVAR complications was high. During a median follow-up of 20 months, AAA-associated mortality is low, but the need for renewed (endovascular) reinterventions is substantial.

CT angiography to evaluate hemodynamic changes in popliteal artery aneurysms during flexion and extension of the knee joint.

AIM: The aim of this study was to find out which characteristics of an asymptomatic popliteal artery aneurysm (PAA) will increase the risk for acute thrombosis. METHODS: This was a single-center prospective study of consecutive patients with asymptomatic PAAs presenting from January 2010 to April 2012. Computed tomography angiography was used to perform measurements of the PAA during 0º extension and 90º flexion of the knee. After semi-automated segmentation of the popliteal artery (PA) lumen, a center lumen line (CLL) was automatically constructed. RESULTS: The study included 16 asymptomatic PAAs. Median lumen area of the PA was directly proximal and distal of the PAA 57 mm2 (IQR, 44-87 mm2) and 46 mm2 (IQR, 32-66 mm2) in extension vs. 51 mm2 (IQR, 38-73 mm2) and 38 mm2 (IQR, 30-62 mm2) during 90º flexion, respectively (P=0.007) and (P=0.03). The median of the greatest decrease in lumen area after flexion and extension of the knee was 36 mm (IQR, 28-48 mm) in PAAs≥30 mm compared with 11 mm (IQR, 4-18 mm) in PAAs<30 mm (P<0.05). The proximal angulation was a median 48° in extension (IQR, 27-61º) and 75° during flexion (IQR, 46-99º; P=0.02). Distal angulation was a median of 31° (IQR, 21-42º) after extension vs. 62° (IQR, 33-81º) during flexion (P=0.03). CONCLUSION: Knee bending in patients with PAAs will lead to a reduction in the lumen area of the PAA and a change in the degree of angulation of the PAA. A significant decrease in lumen area was seen in PAAs≥30 mm compared with PAAs<30 mm after flexion of the knee.

First- and second-generation drug-eluting balloons for femoro-popliteal arterial obstructions: update of technique and results.

The use of drug-eluting balloons for treatment of long-segment femoropopliteal artery obstructions has become widespread in recent years. The possibility to deliver a drug into the arterial wall with sustained antiproliferative effects, without leaving behind metal scaffolding, seems very promising. The current generation of drug-eluting balloons differs in the formulation of the drug (usually paclitaxel), technique of coating, and the elution excipients. Results of published randomized trials are reviewed in this report. A new innovative coating technique has been introduced recently. The PRIMUS® coronary drug-eluting balloon and the Legflow® peripheral drug-eluting balloon consist of paclitaxel nanoparticles that are embedded underneath the surface of the balloon as well as inside a new shellolic acid drug-release matrix. Risk for dislodgement of the paclitaxel particles is minimized in the newest generation of drug-eluting balloons. Short-term in vitro and in vivo results of this stable, coated balloon are promising, and large randomized trials have been started recently to gather more long-term and robust clinical data.

Freedom from secondary interventions to treat stenotic disease after percutaneous transluminal angioplasty of infrarenal aorta: long-term results.

PURPOSE: The purpose of this study was to determine the long-term results (1-15 years) of percutaneous transluminal angioplasty (PTA) of localized atherosclerotic lesions of the infrarenal aorta. METHODS: This was a retrospective study. From January 1987 to January 2002, 69 patients underwent PTA of an isolated stenosis of the lower abdominal aorta under local anesthesia in the department of interventional radiology. All atherosclerotic lesions were hemodynamically significant, defined as a subjective report of walking distance less than one block, resting pain, or trophic changes in combination with diameter reduction of 50% or greater at duplex ultrasound scanning and angiography. RESULTS: The female-male ratio of study patients was 3.6:1; mean age was 58 years. Endovascular treatment was initially technically and clinically successful in all but one patient (98%), who had a near total occlusion. No major complications were noted. Mean follow-up was 57 months (range, 6 months-15 years). At life table analysis, 5-year primary patency was 75%, and secondary patency was 97%. Twelve patients (17%) required repeat interventions because of hemodynamically significant recurrent stenosis in combination with severe clinical symptoms. Most recurrent stenoses (67%) were successfully treated with repeat endovascular procedures. CONCLUSIONS: Early and long-term results of PTA (with additional stent placement) of isolated stenosis of the infrarenal aorta are good. This minimally invasive procedure is a true alternative to traditional surgical methods.