[Pathophysiology of right ventricular hemodynamics]. / Physiopathologie hémodynamique du ventricule droit.

The right ventricle (RV) plays a key role in the maintenance of an adequate cardiac output whatever the demand, and thus contributes to the optimization of the ventilation/perfusion ratio. The RV has a thin wall and it buffers the physiological increases in systemic venous return without causing a deleterious rise in right atrial pressure (RAP). The RV is coupled to the pulmonary circulation which is a low pressure, low resistance, high compliance system. In the healthy subject at rest, the contribution of the RV to right heart systolic function is surpassed by the contribution of both left ventricular contraction and the respiratory pump. RV systolic function plays a contributory role during exercise and in patients with pulmonary hypertension. The RV compensates better for volume overload than for pressure overload and is more capable of sustaining chronic increases in load than acute ones. An impaired RV-pulmonary artery coupling leads to a major mismatch between RV function and arterial load ("afterload mismatch") and is associated progressively with a low cardiac output and a high RAP. Right ventricular dysfunction is involved in the pathophysiology of both cardiovascular and pulmonary diseases, and may partly explain the deleterious haemodynamic consequences of mechanical ventilation.

Efficacy and safety of pre-Descemet's membrane sutures for the management of acute corneal hydrops in keratoconus.

AIMS: The aim of this study was to assess the efficacy and safety of pre-Descemet's membrane (DM) sutures associated with intracameral air injection for management of acute corneal hydrops associated with keratoconus. METHODS: We carried out a retrospective interventional study of seven consecutive cases. Three to seven pre-DM sutures with 10-0 nylon were applied perpendicularly to the tear as close as possible to DM, under general anaesthesia. An air bubble was injected into the anterior chamber at the end of each procedure. RESULTS: Corneal oedema began to decrease from day 1 after surgery in all our patients. Best-corrected visual acuity progressed from 2.13 to 1.65 logMar (p=0.031) 1 month after surgery, and from 2.13 to 0.84 logMar (p=0.016) 2 months after surgery. The mean corneal thickness measured by anterior segment optical coherence tomography decreased from 1472 µm (range 689-2770 µm) on day 0 to 909 µm (range 484-1640 µm) on day 1 (p=0.016), 716 µm (range 484-1380 µm) on day 15 (p=0.016) and 528 µm (range 404-618 µm) 1 month after surgery. CONCLUSIONS: Our results suggest that intrastromal pre-DM sutures and intracameral air injection could promptly restore imperviousness of posterior stroma. This technique seems to be a safe and useful procedure to shorten acute corneal hydrops.

Growth hormone excess and sternohyoid muscle mechanics in rats.

In vitro isotonic and isometric mechanical properties of the sternohyoid (SH) muscle, an upper airway dilator muscle, were studied in rats with a growth hormone (GH)-secreting tumour (GH tumour group; n = 10). The effects of muscle fatigue were also studied. Stress and shortening were measured in muscles contracting from zero load up to isometric load under tetanic conditions. Isometric stress and maximum unloaded shortening velocity were determined and compared with values obtained from control rats (n = 10). Crossbridge kinetics and energetics and mechanical efficiency were calculated from Huxley's equations. Compared with controls, isometric stress, mechanical efficiency, crossbridge number and crossbridge single force were lower in the GH tumour group. The probability of crossbridge being in the power stroke configuration was lower in the GH tumour group than in controls. Muscle fatigue significantly impaired maximal muscle efficiency and crossbridge single force in the GH tumour group but not in controls. In conclusion, mechanical and energetic properties of the SH muscle and crossbridge properties were worse in the GH tumour group than in controls. This may partly account for impairment of the upper airway dilator muscle function and the increased occurrence of obstructive sleep apnoea in acromegaly.

[Endogenous Candida endophthalmitis in drug misusers injecting intravenous buprenorphine]. / Endophtalmie endogène à Candida secondaire à l'utilisation de la buprénorphine par voie intraveineuse.

PURPOSE: To analyze patients presenting ocular candidiasis caused by intravenous drug addiction to buprenorphine. PATIENTS AND METHODS: We have listed all the cases of endogenous fungal endophthalmitis hospitalized between 1996 and 2005 in the ophthalmology department of the university-affiliated hospital of Rouen, France. Posterior vitrectomy was performed for each patient, with direct examination and bacterial and fungal cultures. The treatment was begun both with an intravitreal injection of amphotericin B and oral fluconazole, modified in the event of resistance. RESULTS: Seven men, drug addicts, all using intravenous buprenorphine users, were included in the study. The vitreal culture revealed four cases of Candida albicans candidiasis and one case of Candida tropicalis candidiasis. In two cases, oral fluconazole had to be replaced with oral voriconazole. Of the seven patients, three evolved unfavorably despite treatment. DISCUSSION: Intravenous drug use is known to be a risk factor for ocular candidiasis. However, buprenorphine does not seem to be related to endogenous endophthalmitis, since this was also observed among patients using methadone or heroine. Salivary contact during the preparation of the syringe being used for the injection of the substitute appears to be the source of the candidemia in our series and in the literature. CONCLUSION: Inappropriate intravenous use of oral buprenorphine in drug users is a significant risk factor of endogenous fungal endophthalmitis. Visual monitoring by pharmacists of the oral intake of buprenorphine seems essential. We underline the advantages of removing the vitreous in ocular candidiasis.

Lower respiratory tract foreign bodies: a retrospective review of morbidity, mortality and first aid management.

OBJECTIVES: The authors describe 28 pediatric cases of foreign body inhalation requiring treatment in intensive care units between 1987 and 1999. The purpose of this study was: (1) to analyze the circumstances, diagnostic difficulties and initial treatment of serious foreign bodies and (2) to compare our series with other literature descriptions and define principles for optimal prevention and initial treatment. METHODS: Twenty-one children presented a penetration syndrome, which was responsible in 13 cases for asphyxia with cardiorespiratory arrest. All these children died, regardless of the initial treatment. Seven children were hospitalized for apparent asthmatic symptoms that did not respond to traditional treatment. RESULTS: The inefficiency of external extraction methods like the Heimlich maneuver and the mean delay between clinical signs and initial treatment lead us to propose a new strategy for the emergency treatment of foreign bodies with asphyxia. CONCLUSIONS: We recommend that emergency teams promote the use of a laryngoscope and Magill forceps. Flexible endoscopy is still recommended as the appropriate diagnostic tool to eliminate doubt in the case of a first severe asthma attack.

Telithromycin (HMR 3647) achieves high and sustained concentrations in tonsils of patients undergoing tonsillectomy.

Telithromycin, the first ketolide antimicrobial to be developed for clinical use, has potent activity against group A beta-haemolytic streptococci (GABHS), including macrolide-resistant strains. The penetration of telithromycin into tonsils was assessed in 22 adults undergoing tonsillectomy at 3, 12 or 24 h after the fourth dose of oral telithromycin 800 mg once daily. Telithromycin rapidly penetrated tonsillar tissues, achieving a mean concentration of 3.95 mg/kg at 3 h post dose, 3.4 times greater than the corresponding plasma concentration (1.22 mg/l. The mean tonsil:plasma concentration ratio increased to 13.1 at 24 h post dose, indicating slower elimination from tonsils than plasma. Tonsillar and plasma concentrations exceeded the MIC(50) for GABHS throughout the 24-h dosing period. These findings suggest that telithromycin may be an effective new alternative treatment for GABHS tonsillopharyngitis.

Imaging of MALT lymphomas.

The broad category of non-Hodgkin's lymphoma includes a large variety of different diseases including indolent as well as aggressive lymphomas. Mucosa-associated lymphoid tissue (MALT) lymphoma arises in the extranodal mucosal lymphoid tissue and has only been recognised as a distinct entity in recent years. It affects one or several extranodal structures such as the stomach, the lung, the eye and salivary glands. The lymphoma is generally of low grade and has indolent course. The aim of this article is to exemplify the most common radiological patterns of MALT lymphoma.

Chondromyxoid fibroma of the nasal bone with extension into the frontal and ethmoidal sinuses: report of one case and a review of the literature.

Chondromyxoid fibroma is a rare benign tumor that usually occurs in the long bones. A 50-year-old patient presented with chondromyxoid fibroma of the nasal bone with extension into the frontal and ethmoidal sinuses. This is the fourth case reported to date in the literature. The clinical manifestations of the tumor were very limited, and the appearance at rhinoscopy was misleading. Radiologic imaging showed a soft tissue lesion invading the adjacent bony structures and the dura mater. Surgery was performed by a combined team of otorhinolaryngologists and neurosurgeons, and total excision of the tumor was achieved. The histologic diagnosis of this tumor is difficult because of its similarities to chondrosarcoma. [Editorial comment: The authors concisely review management of this rare tumor, emphasizing that complete surgical excision, rather than curettage, is required for long term control.]

[Short term evaluation of a new treatment method for primary snoring: radiofrequency energy]. / Evaluation à court terme d'une nouvelle méthode de traitement du ronflement simple : l'énergie radiofréquencielle.

The usual treatments for primary snoring are uvulopalatopharyngoplasty (UPPPP) and laser assisted uvulopalatoplasty, their morbidity is known, particularly considerable postoperative pain. We have performed a prospective study on a population of 23 patients with primary snoring (respiratory disturbance index =6 +/- 1) to 1) evaluates by means of questionnaires the short term (2 month) efficacy of the application of radiofrequency energy at the level of the soft palate, and 2) assess the morbidity associated with this treatment in this population. In the group of patients receiving treatment at three sites in a maximum of three sessions, the short term satisfaction rate was 75 %. The postoperative pain was of minor importance and the use of major analgesics was necessary in 2 cases only. We conclude that this treatment with radiofrequency energy seems to be an effective treatment for primary snoring at short term. The morbidity, specially the pain seems to be distinctly inferior compared to UPPP or laser treatment. Further prospective studies on a larger number of patients and with a longer follow-up are absolutely necessary to confirm these results.

Severe mechanical dysfunction in pharyngeal muscle from adult mdx mice.

The mdx mouse is a widely used animal model of human muscular dystrophy. Although diaphragm muscle exhibits severe muscle weakness throughout the life of the animal, the limb muscle function of mdx mice spontaneously recovers by 6 mo of age. Pharyngeal dilator muscles such as sternohyoid (SH) contribute to upper airway patency during breathing. We hypothesized that SH muscle function was impaired in 6-mo-old mdx mice. Mechanical properties and myosin heavy chain (MHC) composition were investigated in isolated SH from 6-mo-old control (C, n = 10) and mdx (n = 10) mice. As compared with C, peak tetanic tension (Pmax) and maximum shortening velocity were 50% and 16% lower in mdx mice (p < 0.001 and p < 0.05, respectively). Peak mechanical power was lower in mdx than in C (19.0 +/- 3.2 versus 57.4 +/- 5.1 mW g(-)(1), p < 0.001). Both C and mdx SH were composed exclusively of fast myosin isoforms. As compared with C, mdx SH presented a higher proportion of IIX-MHC and a reduction in IIB-MHC (each p < 0.001). In conclusion, our results demonstrated severe SH muscle dysfunction in 6-mo-old mdx mice, that is, at a time when limb muscle function has recovered. Thus, SH muscle of the mdx mouse may be an excellent muscle for studying Duchenne muscular dystrophy.

Isotonic mechanics of a pharyngeal dilator muscle and diaphragm in the rat before and after fatigue.

Pharyngeal and diaphragm muscles contract and relax in synergy, which is why it was decided to compare their mechanical performance throughout the overall load continuum. The effects of fatigue were also studied. The isotonic mechanics of rat sternohyoid (SH; n=10) and diaphragm (D; n=10) were investigated in vitro. Force and length were measured in muscles contracting from zero load up to isometry. Maximum isometric tension (Pmax), peak mechanical work (Wmax), maximum unloaded shortening velocity (vzL) and mechanical efficiency (eff(max)) were recorded. Data were obtained both at baseline and after fatigue. SH muscles had a lower Pmax (96.0+/-13.7 versus 119.5+/-22.7 mN x mm(-2); p<0.05), a lower Wmax (5.5+/-1.2 versus 8.0+/-2.1 mJ x g(-1); p<0.01), a lower eff(max) (56.0+/-6.9 versus 62.6+/-5.8%; p<0.05) and a higher vzL (4.8+/-0.4 versus 3.4+/-0.4 initial length (L0) x s(-1); p<0.001) than D muscles. Wmax occurred at a higher relative load in SH (40% Pmax) than in D (30% Pmax). Fatigue did not modify eff(max) in SH muscles, whereas it significantly improved eff(max) in D muscles. These findings suggest that under control conditions, economy of force generation was less efficient in sternohyoid than in diaphragm muscles. Fatigue in sternohyoid muscles induced unfavourable mechanical behaviour. This may partly explain pharyngeal dilator muscle failure in the presence of increased loads. Whether these findings are relevant to human sleep apnoea syndrome has yet to be determined.

Myosin molecular motor dysfunction in dystrophic mouse diaphragm.

Cross-bridge properties and myosin heavy chain (MHC) composition were investigated in isolated diaphragm from 6-mo-old control (n = 12) and mdx (n = 12) mice. Compared with control, peak tetanic tension fell by 50% in mdx mice (P < 0.001). The total number of cross bridges per square millimeter (x10(9)), the elementary force per cross bridge, and the peak mechanical efficiency were lower in mdx than in control mice (each P < 0.001). The duration of the cycle and the rate constant for cross-bridge detachment were significantly lower in mdx than in control mice. In the overall population, there was a linear relationship between peak tetanic tension and either total number of cross bridges per square millimeter or elementary force per cross bridge (r = 0.996 and r = 0.667, respectively, each P < 0.001). The mdx mice presented a higher proportion of type IIA MHC (P < 0.001) than control mice and a reduction in type IIX MHC (P < 0.001) and slow myosin isoforms (P < 0.01) compared with control mice. We concluded that, in mdx mice, impaired diaphragm strength was associated with qualitative and quantitative changes in myosin molecular motors. It is proposed that reduced force generated per cross bridge contributed to diaphragm weakness in mdx mice.

Impaired load dependence of diaphragm relaxation during congestive heart failure in the rabbit.

The load dependence (LD) of relaxation was studied in the diaphragm of rabbits with congestive heart failure (CHF). CHF (n = 15) was induced by combined chronic volume and pressure overload. Aortic insufficiency was induced by forcing a catheter through the aortic sigmoid valves, followed 3 wk later by abdominal aortic stenosis. Six weeks after the first intervention, animals developed CHF. Sham-operated animals served as controls (C; n = 12). Diaphragm mechanics were studied in vitro on isolated strips, at 22 degrees C, in isotonic and isometric loading conditions. Contractility was lower in the CHF group, as reflected by lower total tension: 1.11 +/- 0.10 in CHF vs. 2.38 +/- 0.15 N/cm(2) in C in twitch (P < 0.001) and 2.46 +/- 0.22 in CHF vs. 4.90 +/- 0.25 N. cm(-2) in C in tetanus (P < 0.001). The index LD was used to quantify the load dependence of relaxation: LD is <1 in load-dependent muscles and tends toward 1 in load-independent muscles. LD was significantly higher in CHF than in C rabbits, in both twitch (0.99 +/- 0.01 vs. 0.75 +/- 0.03; P < 0. 001) and tetanus (0.95 +/- 0.02 vs. 0.84 +/- 0.02; P < 0.001). In the CHF rabbits' diaphragm, the fall in total tension was linearly related to the fall in load dependence of relaxation. The decrease in load dependence of relaxation in CHF animals suggests sarcoplasmic reticulum abnormalities. Impairment of the sarcoplasmic reticulum may also partly account for the decrease in contractile performance of diaphragm in CHF animals.

Cross-bridge kinetics in fatigued mouse diaphragm.

The aim of this study was to determine cross-bridge number and kinetics in the diaphragm during fatigue and early recovery. Experiments were conducted in isolated mouse diaphragm (n=10). The force of a single cross-bridge (pi), the number of cross-bridges (m x 10(9) x mm2), the time cycle (tc) and the rate constants for cross-bridge attachment (f1) and detachment (g2) were calculated from the equations of A.F. Huxley. Following the fatigue protocol, peak isometric tension (Po) and maximum unloaded shortening velocity fell by 40+/-1% and 17+/-2%, respectively. In fatigued diaphragm, m fell by approximately 40% and returned to baseline after 10 min. When compared to baseline, g2 fell in fatigued diaphragm and remained significantly lower during the 15-min recovery period. In contrast, fatigue did not significantly modify pi, f1, or tc. There was a strong linear relationship between Po and m (p<0.001, r=0.988). No relationship was observed between tc and g2. These results indicate that changes in tension during fatigue and recovery run parallel to changes in the number of active cross-bridges, with no change in the force generated per cross-bridge. It is conceivable that fatigue durably impairs adenosine diphosphate release from the actomyosin complex without modifying the total duration of the cross-bridge cycle.

Congenital tracheoesophageal fistula without esophageal atresia.

The authors report a series of eight cases of isolated tracheoesophageal fistula without esophageal atresia (or an H type fistula), treated in three pediatric ENT departments. This is a rare malformation whose diagnosis requires investigation for associated anomalies. The clinical signs are mainly respiratory but also digestive and the symptomatology can be severe. The diagnosis can be made with a barium swallow combined with cineradiography, but a tracheoesophageal endoscopy remains the investigation of choice. The treatment is surgical. In most cases, the fistula is accessible by a right or left cervicotomy, depending on the surgeon's practice, with a much lower postoperative morbidity as compared to a thoracotomy. The postoperative management was straightforward in most of our cases. We discuss the role of gastro-esophageal reflux with respect to postoperative morbidity as well as systematic treatment for reflux peri-operatively. The pros and cons of the various surgical approaches are also discussed.

Laryngotracheal manifestations of gastroesophageal reflux in children.

Gastroesophageal reflux is generally a benign condition, which resolves spontaneously, and which is usually manifested by digestive signs. More recently, laryngotracheal conditions such as laryngospasm, laryngomalacia and recurrent laryngitis, have been ascribed to gastroesophageal reflux. However, there is not a single common mechanism linking these two pathologies and different theories are postulated. Diagnosis of gastroesophageal reflux is based essentially on prolonged pH monitoring, where a negative result unfortunately cannot rule out reflux responsibility. Thus, in the end, in the face of a sufficient body of evidence, it is the effectiveness of the anti-reflux treatment which will make it possible to establish a link between gastroesophageal reflux and the laryngotracheal manifestations observed.

Anomalous vessel in the middle ear: the role of CT and MR angiography.

An 8-year-old child was examined because of conductive hearing loss with a retrotympanic mass on otoscopy. CT and MR angiography showed a large inferior tympanic artery traversing the hypotympanum and joining a thin, irregular internal carotid artery with a normal middle meningeal artery. These investigations, coupled with knowledge of the embryological development allowed a diagnosis of a complex vascular anomaly in the middle ear and avoided potential surgical complications.