Stent-assisted coiling of intracranial aneurysms located on small vessels: midterm results with the LVIS Junior stent in 40 patients with 43 aneurysms.

INTRODUCTION: The Low-profile Visualized Intraluminal Support (LVIS) Junior stent is dedicated for endovascular treatment of wide-neck intracranial aneurysms located on small-diameter vessels (2-3.5 mm). This study reports midterm clinical and anatomical results of this device. METHODS: This study was approved by authors' ethical committees. A retrospective review of our prospectively maintained database identified all patients treated by this stent in three institutions. Technical issues and immediate and mid-term anatomical and clinical outcomes were evaluated. RESULTS: Forty patients (30 women/10 men, mean age of 55 years) with 43 aneurysms were identified. Mean aneurysm diameter was 5.6 mm (range, 2-13 mm). In all patients, treatment was successful and the stent could be precisely placed. There were three procedure-related complications, one stent thrombosis and two aneurysm ruptures, leading to immediate morbidity in one patient. Delayed ischemic events occurred in three patients including two transient attacks and one permanent deficit. The overall permanent morbidity rate was thus 5 %. No mortality occurred. Immediate aneurysm occlusion consisted of 36 complete occlusions (83.7 %), five neck remnants (11.6 %), and two incomplete occlusions (4.7 %). Twenty-seven patients (29 aneurysms) and 11 patients (11 aneurysms) had a 12- and 6-month angiographic follow-up, respectively. Final anatomical results included 36 complete occlusions (90 %) and four neck remnants (10 %). Two minor recanalizations were seen but did not require retreatment. Non-significant intrastent stenosis occurred in 7/40 followed-up cases (17.5 %). CONCLUSION: The LVIS Junior stent appears safe and effective for endovascular treatment of wide-neck intracranial aneurysms located on small vessels. Midterm results show high rates of adequate and stable occlusion.

Single-breath test in lateral decubitus reflects function of single lungs grafted for emphysema.

The slope of alveolar plateau for nitrogen derived from the single-breath test is useful to assess the function of bilateral lung grafts, but this technique is not applicable to patients with single-lung grafts due to the confounding influence of the native lung. We tested the hypothesis that the nitrogen slope measured in lateral decubitus with the graft in nondependent position may primarily reflect the distribution of ventilation in this lung. Fifteen patients with single-lung transplantation for emphysema, 10 healthy controls, and 7 patients with advanced emphysema performed single-breath washouts in right and left lateral decubitus; nitrogen slope was measured between 75 and 100% of expired volume. In 10 transplant recipients, the volume of each lung was measured in the two postures by computerized tomography. Nitrogen slope was unaffected by posture in normal controls and emphysema patients. On the other hand, nitrogen slope in transplant recipients was invariably smaller, with the graft in nondependent vs. in dependent position. Values of nitrogen slope with the graft in nondependent position were similar to those obtained in normal controls but significantly smaller than those obtained in emphysema patients. Computerized tomography studies in this position indicated that the volume expired below functional residual capacity was exclusively contributed by the graft. We conclude that, in patients with single-lung transplantation for emphysema, 1) measuring nitrogen slope in lateral decubitus allows to distinguish between the graft and the native lung, and 2) nitrogen slope obtained with the graft in nondependent position reflects ventilation distribution in this lung.

The Silk flow-diverter stent for endovascular treatment of intracranial aneurysms.

Flow diverter (FD) stents represent a new endovascular technique developed for the treatment of complex intracranial aneurysms (wide neck, fusiform, large, and giant aneurysms) that are challenging for classic endovascular techniques such as coiling, balloon-assisted coiling and stent-assisted coiling. Low porosity, high metal coverage, and high pore density are the main properties of FD stents. These properties induce hemodynamic changes redirecting the blood flow away from the aneurysm and into the parent artery leading to gradual thrombosis of the aneurysm. FD stents also provide scaffolding for subsequent neoendothelial proliferation, and vessel wall remodeling. This is considered as a paradigm shift compared to prior endovascular methods, which predominantly aimed at providing treatment inside the aneurysmal sac. This paper describes in detail the first released FD stent, the Silk flow-diverter stent (Balt Extrusion, Montmorency, France), its mechanism of action and deployment technique. It reviews the pertinent literature regarding safety, efficacy and potential risks and complications associated with the use of this stent.

Abnormal pulmonary vascular tone in canine oleic acid lung injury.

OBJECTIVE: To characterize the endothelium-dependent and endothelium-independent components of abnormal pulmonary vascular tone in canine oleic acid lung injury. DESIGN: Prospective, interventional study. SETTING: University laboratory. SUBJECTS: Twenty anesthetized mongrel dogs. INTERVENTIONS: Right heart catheterization was performed to measure pulmonary vascular resistance before and after induction of oleic acid lung injury in ten anesthetized and ventilated dogs. Pulmonary and internal mammary artery rings were sampled in these ten dogs with oleic acid injury and in ten anesthetized healthy control dogs. We also studied the responses to acetylcholine, to phenylephrine, and to hypoxia of the intact or endothelium-denuded rings mounted in organ baths. MEASUREMENTS AND MAIN RESULTS: Oleic acid lung injury was associated with an increase in pulmonary vascular resistance from 118 +/- 11 to 245 +/- 47 dyne.sec.cm-5.m-2 and a decrease in the Pao2/Fio2 ratio from 451 +/- 42 to 139 +/- 26 mm Hg (mean +/- se, p <.05 and p <.01, respectively). Acetylcholine-induced relaxation was decreased in the oleic acid pulmonary artery rings compared with the controls (85 +/- 3% vs. 99 +/- 6% of precontraction level, p <.05). Phenylephrine-induced contraction was decreased in denuded oleic acid pulmonary artery rings compared with the controls (81 +/- 8% vs. 102 +/- 10% of contraction to KCl 120 mM, p <.05). In vitro hypoxia induced a small endothelium-dependent contraction followed by an endothelium-independent relaxation. These responses were not different in oleic acid lung artery rings and in controls, except for a decrease in hypoxic contraction in the oleic acid pulmonary artery rings. In vitro hypoxic pulmonary vasoconstriction and relaxation were, respectively, directly (r =.48) and inversely (r = -.67) correlated with oleic acid-induced increase in pulmonary vascular resistance. There was no correlation between in vitro internal mammary artery reactivity and oleic acid-induced increase in pulmonary vascular resistance. CONCLUSIONS: Oleic acid-induced lung injury slightly impairs pulmonary arterial endothelium-dependent relaxation and endothelium-independent contraction. In vitro hypoxic pulmonary vasoreactivity is related to in vivo oleic acid-induced increase in pulmonary vascular resistance.

Air trapping in heart-lung transplant recipients: variability of anatomic distribution and extent at sequential expiratory thin-section CT.

PURPOSE: To evaluate the intrapatient reproducibility of the extent and anatomic distribution of air trapping at sequential expiratory thin-section computed tomographic (CT) examinations in heart-lung transplant recipients. MATERIALS AND METHODS: Nineteen heart-lung transplant recipients (eight with and 11 without bronchiolitis obliterans syndrome [BOS]) underwent three expiratory CT examinations within 1 hour. Residual volumes were measured at CT. Anatomic distribution and extent of air trapping were scored by two observers at two independent readings, and the reproducibility of observations was calculated for each feature. CT examination results were compared by using an analysis of variance that took into account interobserver and BOS and non-BOS effects. The Spearman rank correlation coefficient was calculated to test the association between variability of residual volumes and variability of the extent of air trapping. RESULTS: Residual volumes did not significantly differ between the three CT examinations (P =.556). Reproducibility values for findings of anatomic distribution of air trapping ranged from 84% to 95%, with a tendency toward improved reproducibility in patients without BOS. Mean reproducibility values for the extent of air trapping ranged from 97.1% to 97.7%, and no substantial difference in these values between patients with and those without BOS was observed. The Spearman rank coefficient for the correlation between variability of residual volumes and variability of extent of air trapping ranged from 0.382 to 0.568 (P =.105-.016). No interobserver effect was detected (P =.944). CONCLUSION: Anatomic distribution and extent are reproducible characteristics of air trapping. No substantial variability of air trapping occurs in functionally stable heart-lung transplant recipients.

Function and bulk of respiratory and limb muscles in patients with cystic fibrosis.

Inspiratory muscle weakness due to lung hyperinflation and muscle wasting may occur in cystic fibrosis. We therefore measured diaphragm function and bulk in 18 stable patients with cystic fibrosis and 15 matched control subjects; the abdominal and quadriceps muscles were studied for comparison. We assessed diaphragm mass, abdominal muscle thickness, twitch transdiaphragmatic and gastric pressures, quadriceps cross-section and isokinetic strength, and lean body mass. Lean body mass, quadriceps strength, and quadriceps cross-section were lower in patients with cystic fibrosis. Twitch transdiaphragmatic pressure was 23% lower and twitch gastric pressure was 22% greater in patients with cystic fibrosis than in control subjects, but diaphragm mass and abdominal muscle thickness were similar in the two groups. For any given lean body mass and quadriceps cross-section, patients with cystic fibrosis had greater diaphragm mass and abdominal muscle thickness. Diaphragm mass had greater intersubject variability in patients with cystic fibrosis than in control subjects. We conclude that diaphragm strength is decreased but abdominal muscle strength is increased in patients with cystic fibrosis. Diaphragm and abdominal muscle bulk are not affected by the general muscle wasting, which suggests that there may be a training effect of cystic fibrosis on respiratory muscles. However, the variability of diaphragm mass indicates that this beneficial response does not occur in all patients with cystic fibrosis.

Ventilation asymmetry after transplantation for emphysema: role of chest wall and mediastinum.

After single-lung transplantation for emphysema, the hyperinflated native lung and the graft have different extents and rates of inflation and emptying. This requires that breathing produces asymmetrical expansion of the chest wall, displacement of the mediastinum, or both. In a first study in four seated transplant recipients, we measured the volumes of the two hemithoraces with optoelectronic plethysmography. Functional residual capacity and total lung capacity were identical on the native and transplanted sides, and changes in chest wall volume during CO(2)-induced hyperpnea and FVC maneuvers were similar on both sides. Studies with computerized tomography in three of these patients and in four additional patients in supine posture indicated that the mediastinum was shifted toward the graft at functional residual capacity and total lung capacity. The mediastinum moved toward the native lung during tidal and full inspiration and toward the graft during tidal and forced expiration; additional studies with fluoroscopy showed qualitatively similar changes in upright posture. In summary, the two hemithoraces assume identical static volumes and show similar volume changes during CO(2)-induced hyperpnea and FVC maneuvers in patients with single-lung transplantation for emphysema; displacement of the mediastinum accommodates part, if not all, of the unequal lung volumes and asymmetrical ventilation.