Christian Loewe

Balloon angioplasty versus implantation of nitinol stents in the superficial femoral artery

BACKGROUND Because stent implantation for disease of the superficial femoral artery has been associated with high rates of late clinical failure, percutaneous transluminal angioplasty is preferred for endovascular treatment, and stenting is recommended only in the event of suboptimal technical results. We evaluated whether primary implantation of a self-expanding nitinol (nickel-titanium) stent yielded anatomical and clinical benefits superior to those afforded by percutaneous transluminal angioplasty with optional secondary stenting. METHODS We randomly assigned 104 patients who had severe claudication or chronic limb ischemia due to stenosis or occlusion of the superficial femoral artery to undergo primary stent implantation (51 patients) or angioplasty (53 patients). Restenosis and clinical outcomes were assessed at 6 and 12 months. RESULTS The mean (+/-SD) length of the treated segment was 132+/-71 mm in the stent group and 127+/-55 mm in the angioplasty group. Secondary stenting was performed in 17 of 53 patients (32 percent) in the angioplasty group, in most cases because of a suboptimal result after angioplasty. At 6 months, the rate of restenosis on angiography was 24 percent in the stent group and 43 percent in the angioplasty group (P=0.05); at 12 months the rates on duplex ultrasonography were 37 percent and 63 percent, respectively (P=0.01). Patients in the stent group were able to walk significantly farther on a treadmill at 6 and 12 months than those in the angioplasty group. CONCLUSIONS In the intermediate term, treatment of superficial-femoral-artery disease by primary implantation of a self-expanding nitinol stent yielded results that were superior to those with the currently recommended approach of balloon angioplasty with optional secondary stenting. (ClinicalTrials.gov number, NCT00281060.).

Sustained Benefit at 2 Years of Primary Femoropopliteal Stenting Compared With Balloon Angioplasty With Optional Stenting

Background— Primary stenting with self-expanding nitinol stents of the superficial femoral artery yielded improved morphological and clinical results compared with balloon angioplasty with optional stenting until 12 months in a randomized controlled trial. We now report 2-year data on restenosis and clinical outcomes of these patients. Methods and Results— Of 104 patients with chronic limb ischemia and superficial femoral artery obstructions, 98 (94%) could be followed up until 2 years after intervention for occurrence of restenosis (>50%) by duplex ultrasound and for clinical and hemodynamic outcome by treadmill walking distance and ankle brachial index. Restenosis rates at 2 years were 45.7% (21 of 46) versus 69.2% (36 of 52) in favor of primary stenting compared with balloon angioplasty with optional secondary stenting by an intention-to-treat analysis (P=0.031). Consistently, stenting (whether primary or secondary; n=63) was superior to plain balloon angioplasty (n=35) with respect to the occurrence of restenosis (49.2% versus 74.3%; P=0.028) by a treatment-received analysis. Clinically, patients in the primary stent group showed a trend toward better treadmill walking capacity (average, 302 versus 196 m; P=0.12) and better ankle brachial index values (average, 0.88 versus 0.78; P=0.09) at 2 years, respectively. Reintervention rates tended to be lower after primary stenting (17 of 46 [37.0%] versus 28 of 52 [53.8%]; P=0.14). Conclusions— At 2 years, primary stenting with self-expanding nitinol stents for the treatment of superficial femoral artery obstructions yields a sustained morphological benefit and a trend toward clinical benefit compared with balloon angioplasty with optional stenting.

Balloon angioplasty versus stenting with nitinol stents in intermediate length superficial femoral artery lesions.

Background: Recent randomized trials investigating stent implantation compared with balloon angioplasty for treatment of superficial femoral artery (SFA) disease have given divergent results in short (mean 5 cm) and intermediate (mean 10 cm) lesions. We reinvestigated whether primary nitinol stenting is associated with a morphologic and clinical benefit when compared with percutaneous transluminal angioplasty with optional stenting (PTA) in intermediate‐length lesions. Methods: We randomly assigned 73 patients with severe claudication or chronic limb ischemia and average 8 cm long (range 3–20 cm) SFA stenosis or occlusion to primary stent implantation (n = 34) or PTA (n = 39). Restenosis >50% and clinical outcome were assessed at 3, 6, and 12 months postintervention. Results: Average length of the treated segments was 98 ± 54 mm and 71 ± 43 mm in the stent and PTA groups (P = 0.011), respectively. In the PTA group, secondary stenting was performed in 10 of 39 patients (26%) due to a suboptimal result after balloon dilation. Restenosis rates in the stent and PTA groups were 21.9% versus 55.6% (P = 0.005) at 6 months by CT‐angiography, and 2.9% versus 18.9% (P = 0.033), 18.2% versus 50.0% (P = 0.006), and 34.4% versus 61.1% (P = 0.028) at 3, 6, and 12 months by sonography, respectively. Clinically, patients in the stent group reported a significantly higher maximum walking capacity compared with the PTA group at 6 and 12 months. Conclusion: In this randomized multicenter trial, primary stenting with a self‐expanding nitinol stent for treatment of intermediate length SFA disease resulted morphologically and clinically superior midterm results compared with balloon angioplasty with optional secondary stenting.

Usefulness of magnetic resonance imaging of cardiac and paracardiac masses

In this study, magnetic resonance imaging was compared with histology to evaluate the usefulness of magnetic resonance imaging to distinguish malignant from benign cardiac and paracardiac masses in 55 patients. Tumor location, tissue composition, and pericardial or pleural effusion all were identified as key predictors of lesion type. Observers were accurate in the prediction of lesion type (area under curve 0.88 and 0.92), and there was good interobserver variability (Cohens kappa = 0.64).

Mechanisms of symptomatic spinal cord ischemia after TEVAR: insights from the European Registry of Endovascular Aortic Repair Complications (EuREC).

Purpose To test the hypothesis that simultaneous closure of at least 2 independent vascular territories supplying the spinal cord and/or prolonged hypotension may be associated with symptomatic spinal cord ischemia (SCI) after thoracic endovascular aortic repair (TEVAR). Methods A pattern matching algorithm was used to develop a risk model for symptomatic SCI using a prospective 63-patient single-center cohort to test the positive predictive value (PPV) of prolonged intraoperative hypotension and/or simultaneous closure of at least 2 of 4 the vascular territories supplying the spinal cord (left subclavian, intercostal, lumbar, and hypogastric arteries). This risk model was then applied to data extracted from the multicenter European Registry on Endovascular Aortic Repair Complications (EuREC). Between 2002 and 2010, the 19 centers participating in EuREC reported 38 (1.7%) cases of symptomatic spinal cord ischemia among the 2235 patients in the database. Results In the single-center cohort, direct correlations were seen between the occurrence of symptomatic SCI and both prolonged intraoperative hypotension (PPV 1.00, 95% CI 0.22 to 1.00, p=0.04) and simultaneous closure of at least 2 independent spinal cord vascular territories (PPV 0.67, 95% CI 0.24 to 0.91, p=0.005). Previous closure of a single vascular territory was not associated with an increased risk of symptomatic spinal cord ischemia (PPV 0.07, 95% CI 0.01 to 0.16, p=0.56). The combination of prolonged hypotension and simultaneous closure of at least 2 territories exhibited the strongest association (PPV 0.75, 95% CI 0.38 to 0.75, p<0.0001). Applying the model to the entire EuREC cohort found an almost perfect agreement between the predicted and observed risk factors (kappa 0.77, 95% CI 0.65 to 0.90). Conclusion Extensive coverage of intercostal arteries alone by a thoracic stent-graft is not associated with symptomatic SCI; however, simultaneous closure of at least 2 vascular territories supplying the spinal cord is highly relevant, especially in combination with prolonged intraoperative hypotension. As such, these results further emphasize the need to preserve the left subclavian artery during TEVAR.

MR angiography vs CT angiography in the follow-up of nitinol stent grafts in endoluminally treated aortic aneurysms

Abstract. Our objective was to evaluate the accuracy of contrast-enhanced 3D MR angiography (MRA) in the follow-up of patients with endoluminally treated aortic aneurysms and correlate these findings with uni- or biphasic CT angiography (CTA). Forty MR angiograms in 32 patients with implanted aortic nitinol stent grafts were compared to CTA. Twenty-two MR examinations were correlated with arterial-phase CTA (uniphasic), and 18 MR examinations were correlated with biphasic CTA. Uniphasic CTA demonstrated three type-1/type-3 endoleaks and four reperfusion (type-2) endoleaks. In addition, MRA depicted two type-2 reperfusion endoleaks that were missed by CTA. Using biphasic CTA, two type-1/type-3 endoleaks and three reperfusion (type-2) endoleaks were detected; of those, delayed scanning detected three reperfusion (type-2) endoleaks missed during arterial-phase CTA. In addition to the findings by CTA, MRA depicted another type-2 reperfusion endoleak. Magnetic resonance angiography is at least as sensitive as uni- or biphasic CTA for detecting endoleaks and may consequently offer advantages in patients with contraindications to iodinated contrast agents.

Endovascular Management of Lost or Misplaced Intravascular Objects: Experiences of 12 Years

This paper reports our experience with endovascular techniques for the retrieval of lost or misplaced intravascular objects. Over 12 years, 78 patients were referred for interventional retrieval of intravascular foreign objects. In this retrospective study, radiological procedure records and patients’ medical records were reviewed to determine the exact removal procedure in every case, to report success rates, and to identify significant procedure-related complications. Written, informed consent was obtained from all patients prior to the intervention; this retrospective analysis was performed according to the guidelines of the Institutional Review Board. Thirty-six of seventy-eight foreign objects (46%) were located in the venous system, 27 of 78 (35%) in the right heart, and 15 of 78 (19%) in the pulmonary arteries. For foreign object removal, in 71 of 78 (91%) cases a snare loop was used, in 6 of 78 (8%) cases a sidewinder catheter combined with a snare loop was used, and in 1 case (1%) a sidewinder catheter alone was used for foreign object removal. In 68 of 78 (87%) cases, primary success was achieved. In 3 of 78 cases (4%), foreign objects were successfully mobilized to the femoral vessels and surgically removed. In 7 of 78 cases (9%), complete removal of the foreign object was not possible. In 5 of 78 cases (6%), minor complications occurred during the removal procedure. In conclusion, endovascular retrieval of lost or misplaced intravascular objects is highly effective, with relatively few minor complications. On the basis of our findings, these techniques should be considered as the therapy of choice.

Novel Insights Into the Mechanisms and Treatment of Intramural Hematoma Affecting the Entire Thoracic Aorta

BACKGROUND The purpose of this study was to address a previously not described mechanism underlying intramural hematoma (IMH) of the entire thoracic aorta and to test the hypothesis whether endovascular stent graft placement in this particular mechanism could be beneficial. METHODS Within a 5-year period, we treated 8 patients with IMH affecting the entire thoracic aorta. The presumed site of initial plaque rupture was chosen as target for endovascular stent graft placement. RESULTS In all patients, a small atherosclerotic plaque at the free lateral wall or at the concavity of the distal aortic arch could be identified as initial site of IMH. Endovascular stent graft placement was performed successfully in all patients. By covering the suspected primary lesion, resorption of IMH especially within the ascending aorta could be achieved. Mean follow-up is 16 months (range, 1 to 25). CONCLUSIONS Plaque rupture may be identified as the cause of IMH in a previously unrecognized subgroup of patients. If at the convexity of the distal arch, supra-aortic branches prevent retrograde extension toward the ascending aorta. If at the free lateral wall or at the concavity, IMH may affect the entire thoracic aorta, owing to the lack of the natural barrier of the supra-aortic branches. Endovascular stent graft placement of this plaque-associated IMH may be more effective and less invasive than conventional surgery to treat the entire thoracic aortic disease.

A New Mechanism by Which an Acute Type B Aortic Dissection Is Primarily Complicated, Becomes Complicated, or Remains Uncomplicated

BACKGROUND This study is to evaluate if different locations of the primary entry tear result in primary complicated, secondary complicated, or uncomplicated acute type B aortic dissection. METHODS Sixty-five patients were analyzed. Patients were stratified according to the location of the primary entry tear. Primary entry tears in axial computed tomographic scans at the upper circumference (180°) of the distal aortic arch were defined as convex (group A) and the remaining as concave (group B). Detailed morphometry was done and the clinical outcome, including need for thoracic endovascular aortic repair, was evaluated. RESULTS Forty-two patients (group A) had the primary entry tear at the convexity and 23 patients (group B) had the primary entry tear at the concavity of the distal aortic arch. There was a significant difference with regard to the incidence of primary complicated type B aortic dissection (group A 21% vs group B 61%, p = 0.003) and with regard to the development of complications in group A (9 days; 9 to 37) versus group B (0 days; 0 to 13, p = 0.03). Cox regression analysis revealed a primary entry tear at the concavity to be the only independent predictor of primary or secondary development of a complicated acute type B aortic dissection (hazard ratio, 1.8; 95% confidence interval, 1.0 to 3.2). CONCLUSIONS A primary entry tear at the concavity of the distal aortic arch is associated with a significant increase of the occurrence of complicated acute type B aortic dissection. Due to low procedural risk and high success rates, closure of the primary entry tear with thoracic endovascular aortic repair is strongly recommended in this newly defined high-risk subgroup of patients.

Long-term results of thoracic endovascular aortic repair in atherosclerotic aneurysms involving the descending aorta

OBJECTIVE This study evaluated long-term results of thoracic endovascular aortic repair for atherosclerotic aneurysms involving descending aorta. METHODS One hundred thirteen patients underwent thoracic endovascular aortic repair for this indication from 1996 to 2009. Mean follow-up was 54 ± 38 months (5-144 months). In-hospital mortality, neurologic injury, need for rerouting, occurrence of endoleaks and their treatment, and survival were recorded. RESULTS In-hospital mortality was 5.3%. Transient neurologic injury rate was 2.6%. Previous rerouting was performed in 51%. Assisted early and late type I and III endoleak rates were 7.9% and 5.7%, respectively. Five percent of patients required late surgical conversion. Actuarial survivals were 86%, 60%, and 42% at 1, 5, and 10 years, respectively. Aorta-related actuarial survivals were 94%, 90%, and 83% at 1, 5, and 10 years, respectively. Cox regression analysis revealed higher number of prostheses as independent risk factor for early (hazard ratio, 5.38; 95% confidence interval, 1.68-42.37) and late (hazard ratio, 8.49; 95% confidence interval, 1.09-66.06) endoleak formation. Female sex (hazard ratio, 0.35; 95% confidence interval, 0.13-0.99), no arch involvement (hazard ratio, 0.21; 95% confidence interval, 0.05-0.08), and higher number of prostheses (hazard ratio, 7.95; 95% confidence interval, 1.36-46.58) affected survival. CONCLUSIONS Aorta-related survival is excellent among patients undergoing thoracic endovascular aortic repair for atherosclerotic aneurysms involving the descending aorta. Life-long surveillance remains mandatory, with early and late failure uncommon but still needing consideration. Thoracic endovascular aortic repair in this group of patients remains attractive and has now proven durability.