Dexmedetomidine-mediated neuroprotection against sevoflurane-induced neurotoxicity extends to several brain regions in neonatal rats.

BACKGROUND: Exposure of infant animals to clinically used anaesthetics is associated with acute structural brain abnormalities and development functional alterations. The α 2 -adrenoceptor agonist dexmedetomidine (DEX) induces sedation, analgesia, and provides neuroprotection in experimental brain injury models. However, it is unknown whether DEX also affords protection in the developing brain against anaesthesia using sevoflurane (SEVO), which is commonly used in paediatric anaesthesia. METHODS: Infant rats were exposed on postnatal day seven for six h to 2.5% SEVO and were given i.p. injections of saline or DEX (1-50 µg kg -1 ) three times during the exposure. Level of anaesthesia, respiratory rates, and arterial blood gasses were assessed for each animal. Apoptosis was determined in brain slices immunostained for activated caspase-3 (AC-3) using a computerised approach. RESULTS: SEVO alone induced a surgical plane of anaesthesia, and all animals survived the study. SEVO induced an approximately 10-fold increase in AC-3 positive cells in several cortical and subcortical brain regions compared with untreated control animals. Co-administration of DEX 1 µg kg -1 with SEVO significantly reduced apoptosis in all brain areas, affording the highest protection in the thalamus (84% reduction) and lowest in the hippocampus and cortical areas (∼50% reduction). DEX 5-25 µg kg -1 plus SEVO dose-dependently increased infant rat mortality. CONCLUSIONS: SEVO anaesthesia induced widespread apoptosis in infant rat brain. Co-administration of DEX (1 µg kg -1 ) provided significant protection, whereas DEX (5 µg kg -1 or higher) plus SEVO increased mortality. Our findings suggest that DEX could be an attractive therapeutic for future studies investigating its neuroprotective potential in a translational animal model.

Ca2+ handling and sensitivity in airway smooth muscle: emerging concepts for mechanistic understanding and therapeutic targeting.

Free calcium ions within the cytosol serve as a key secondary messenger system for a diverse range of cellular processes. Dysregulation of cytosolic Ca(2+) handling in airway smooth muscle (ASM) has been implicated in asthma, and it has been hypothesised that this leads, at least in part, to associated changes in both the architecture and function of the lung. Significant research is therefore directed towards furthering our understanding of the mechanisms which control ASM cytosolic calcium, in addition to those regulating the sensitivity of its downstream effector targets to calcium. Key aspects of the recent developments in this field were discussed at the 8th Young Investigators' Symposium on Smooth Muscle (2013, Groningen, The Netherlands), and are outlined in this review.

Regulation of GPCR-mediated smooth muscle contraction: implications for asthma and pulmonary hypertension.

Contractile G-protein-coupled receptors (GPCRs) have emerged as key regulators of smooth muscle contraction, both under healthy and diseased conditions. This brief review will discuss some key topics and novel insights regarding GPCR-mediated airway and vascular smooth muscle contraction as discussed at the 7th International Young Investigators' Symposium on Smooth Muscle (2011, Winnipeg, Manitoba, Canada) and will in particular focus on processes driving Ca(2+)-mobilization and -sensitization.

Biventricular repair of transposition of the great arteries and unbalanced ventricles.

BACKGROUND: It is well established that the arterial switch operation is the surgical procedure of choice in patients with transposition of the great arteries and balanced ventricular anatomy. The surgical approach of choice in patients with transposition but unbalanced ventricular size is unknown. OBJECTIVES: Since the beginning of the arterial switch operation program, patients with transposition of the great arteries and unbalanced ventricles underwent biventricular repair by means of the arterial switch operation and repair of any associated lesions, either through a single or staged surgical procedure. The aim of this retrospective study is to analyze whether this approach can be proposed to such patients. METHODS: Forty-four patients with transposition of the great arteries and unbalanced ventricles underwent this surgical approach since 1984. Two groups were defined: group I had transposition with a dominant right ventricle (n = 28), and group II had transposition with a dominant left ventricle (n = 16). In group I the median age and weight at the arterial switch operation were 8.5 days (range, 5-70 days) and 3.1 kg (range, 1.5-3.7 kg), respectively. The median end-diastolic left ventricular volume, mass, and long-axis ratio were 15 mL/m2 (range, 11-16 mL/m2), 31.5 g/m2 (range, 20-66 g/m2), and 0.85 (range, 0.9-0.7), respectively. The mitral valve diameter was slightly hypoplastic, with a median z value of -1.22 (range, -0.3 to 3.7). In group 2 the median age and weight at the arterial switch operation were 42 days (range, 8 days-15 years) and 3.5 kg (range, 2.8-35 kg), respectively. Associated lesions in this group were coarctation in 9 and single (n = 12) or multiple (n = 4) ventricular septal defects. The median long-axis ratio and tricuspid z value were 0.6 (range, 0.3-0.8) and -0.9 (range, -0.5 to 3.3), respectively. In this group 9 patients had a single-stage procedure with fenestrated ventricular defect patches, atrial septal defect patches, or both; 7 patients underwent the staged approach. RESULTS: In group I there was 1 early death from sepsis after weaning from postoperative extracorporeal membrane oxygenation. Three patients had severe pulmonary hypertension, one of whom died 1 year later. All survivors demonstrated, at discharge from the hospital, equilibrated ventricular size, with a median left ventricular end-diastolic volume of 25 mL/m2 (range, 21-30 mL/m2). In group II there were 2 early and 1 late deaths. All early deaths occurred in patients without voluntary residual intracardiac shunts. Median early postoperative long-axis ratio and tricuspid z value were 0.8 (range, 0.7-1) and -0.2 (range, 0.74 to 1.2), respectively. CONCLUSION: This study demonstrates that the arterial switch operation in patients with transposition of the great arteries and unbalanced ventricles remains a good surgical option.

Surgical management and indication of left ventricular retraining in arterial switch for transposition of the great arteries with intact ventricular septum.

OBJECTIVE: Arterial switch is the operation of reference for the surgical treatment of transposition of the great arteries. In cases of late referral, perinatal complications or early left ventricular (LV) dysfunction, the one stage arterial switch is contra indicated. Anatomical repair remains possible in these patients following a LV retraining. METHODS: From January 1992 to January 2000, a LV retraining was attempted in 22 patients with transposition of the great arteries with intact ventricular septum (TGA IVS), whereas 470 direct arterial switch and 2 Senning were performed. Indication for LV retraining was based on a combination of factors including: an age older than 3 weeks, a "banana shape" aspect of the inter-ventricular septum and mainly a LV mass <35G/m(2). RESULTS: The mean age at LV retraining was 3.2 months ranging from 9 days to 8 months. Usually conducted by sterntomy, it associated a loose PA banding with a LV/RV at 65% with a systemico-pulmonary shunt. The first stage was associated with frequent LV dysfunction and the LV retraining was discontinued in two patients in favor of one Senning and one early switch followed by ECMO. One patient died at first stage from a mediastinitis. Nineteen patients underwent a second stage arterial switch that was performed when the LV mass had reached 50 G/m(2) after a mean delay of 10 days, ranging from 5 days to 6 weeks. After a mean follow up of 25 months, there was one non-cardiac late death. The 17 patients followed and leaving with an arterial switch are in NYHA class I, with a mean LV shortening fraction of 39%. CONCLUSIONS: Arterial switch following LV retraining in TGA IVS is a satisfactory option. The inferior limit of 35 G/m(2) adopted, to indicate LV retraining, seems a safe landmark. The quality of the myocardium generated and the respective roles played by the LV afterload, LV wall shear stress, LV inflow and outflow to induce the LV remodeling remain under debate.

[Enlarging angioplasty of the aortic arch with an pulmonary artery autograft patch. Interest in a single-stage repair of the syndrome of coarctation and interruption of the aortic arch]. / Angioplastie d'agrandissement de la crosse aortique par un patch d'autogreffe pulmonaire. Intérêt dans la réparation en un temps des syndromes de coarctation et interruption de l'arche aortique.

Single stage repair of syndromes of coarctation and interruption of the aortic arch is a routine procedure in many surgical centres with good immediate results. The classical technique of aortic repair is based on the principles of Crafoord's extended resection anastomosis. Recoarctation is not an unusual long-term complication. A technique of enlarging angioplasty of the aorta using a patch of pulmonary artery has been developed and used in 22 neonates with obstruction of the aortic arch associated with ventricular septal defect with an average age and body weight of 15 days and 2.9 Kg respectively. The ventricular septal defect was closed surgically during the same procedure. Total circulatory arrest was not used in these children and all had aortic repairs with selective cerebral perfusion with moderate hypothermia (28-30 degrees C). This technique was used without any procedure-related early morbidity. No early or late deaths were observed in this series. Two patients were reoperated during the first year after the initial procedure: one for residual ventricular septal defect and the other for supraventricular pulmonary stenosis. Two patients, one of whom was reoperated, developed supraventricular pulmonary stenosis with a gradient of over 60 mmHg. These stenoses were observed in the first cases operated and were essentially due to the technique of pulmonary artery reconstruction. Over a median follow-up period of 10 months, no recoarctations were observed: the Doppler ultrasound study showed an isolated mean systolic gradient of 6 +/- 12 mmHg. The authors conclude that angioplasty of the aortic arch with an enlarging patch of pulmonary artery autograft during single stage surgery of syndromes of coarctation and interruption of the aortic arch provides a harmonious and durable repair of the aortic arch.

Congenital mitral stenosis with or without associated defects: An evolving surgical strategy.

BACKGROUND: Congenital mitral stenosis (CMS) remains a surgical challenge, particularly when it is associated with other heart defects. As in other groups of heart defects, there is a trend toward early single-stage complete repair, but the optimal surgical approach remains unanswered. METHODS AND RESULTS: This study was designed to analyze the evolution of surgical strategies in patients with CMS and associated defects through single-stage and staged repair. Between 1980 and 1999, 72 children were operated on for congenital heart defects, including CMS. Preoperative transmitral gradient was 12.6+/-7 mm Hg. Preoperatively, all the patients were NYHA class III to IV. Thirteen patients had an isolated CMS; in 59, it was associated with other heart defects, mainly ventricular septal defect (n=28) or multilevel left ventricular obstruction (n=41). In this group of patients, 33 had a staged approach, and 26 had a single-stage approach. Early mortality was 12.5% (9 patients). There were no deaths in the isolated CMS and single-stage repair groups. Logistic regression revealed that early mortality was influenced by association with left ventricular outflow tract obstruction (P:<0.001) and by use of a staged approach (P:<0.01). There was no late mortality in isolated CMS; there were 2 late deaths in the group of single-stage repair and 6 late deaths in the staged approach group (P:<0.01). Reoperation was required in 24 patients, mainly for residual mitral valve dysfunction or residual left ventricular outflow tract obstruction. Including the reoperations, 10 patients received a prosthetic mitral valve. At 15 years after surgery, survival was 69.6+/-7.5%, freedom from reoperation was 70.8+/-6.3%, and freedom from mitral valve replacement was 69+/-6%. CONCLUSIONS: Surgery for isolated CMS gives excellent early and long-term results. In patients with associated heart defects, a single-stage operation seems superior to a staged approach. Mitral valve replacement in this category of patients should be reserved as a salvage procedure.

Surgical management of progressive pulmonary venous obstruction after repair of total anomalous pulmonary venous connection.

BACKGROUND: The occurrence of a progressive pulmonary venous obstruction after the repair of the total anomalous pulmonary venous connection is a severe complication. OBJECTIVES: The objectives of this study were to retrospectively review the patients with this condition and to report our experience with a new surgical technique with a sutureless in situ pericardium repair. METHODS: Of 178 patients who underwent correction of total anomalous pulmonary venous connection, 16 patients (9%) experienced the development of a progressive pulmonary venous obstruction in a median interval of 4 months (5 weeks-12 years). Three patients had isolated anastomotic stenosis, 4 patients had isolated pulmonary venous ostial stenosis, and 9 patients had both. Pulmonary venous obstruction was bilateral in 7 patients. The surgical procedures used at reoperation included 8 patch enlargements, 5 ostial endarterectomies, 1 intraoperative stenting, and 7 sutureless in situ pericardium repairs. RESULTS: There were 4 deaths after reoperation (4 of 15 patients; 27%). The only significant mortality risk factor was the bilateral location of the pulmonary venous obstruction (P =.045). In patients with isolated anastomotic stenosis or with only 1 pulmonary venous ostial stenosis (n = 5), there was no death, except the patient presenting with a single ventricle. In patients with 2 or more pulmonary venous ostial stenoses (n = 10), there were 3 deaths; 5 of the 7 survivors were successfully treated with the in situ pericardial technique, with normalized pulmonary artery pressure at a mean follow-up of 26 months. CONCLUSION: Progressive pulmonary venous stenosis after repair of total anomalous pulmonary venous connection remains a severe complication when bilateral. The sutureless in situ pericardial repair offers a satisfactory solution, particularly on the right side.

[Value of the spiral angio-scanner with three-dimensional reconstruction in the surgical strategy of unifocalization. Apropos of a case]. / Apport de l'angioscanner hélicoïdal avec reconstruction tridimensionnelle dans la stratégie opératoire des unifocalisations. A propos d'une observation.

One of the difficulties of surgical treatment of pulmonary atresia with patent septum by unifocalisation resides in the accurate diagnosis of the different collateral vessels to the lung in order to optimise the surgical approach: anterior or posterolateral thoracotomy, and to determine the type of operation: one or two stages repair. Conventional angiography, even using different views, cannot always give an accurate representation of the anatomy of the different collateral vessels, especially their relationship to the bronchial structures. The authors report the contribution of spiral angioscanner with three dimensional reconstruction in the determination of the operative strategy of a case of pulmonary atresia with patent septum.