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Biomedical subjects

Younes Boudjemline

Publications and source records attributed to Younes Boudjemline.

At least 19 recordsLinked to original sources
PubMed2006

Development of a device for transcatheter pulmonary artery banding: evaluation in animals.

AIMS: Pulmonary artery banding (PAB) is the first palliation in infants with complex congenital heart disease and elevated pulmonary blood flow. In older patients with corrected transposition of the great arteries, it may be used to re-train the left ventricle. To date, the only option is surgical. We report the development and the evaluation of a device for transcatheter PAB. METHODS AND RESULTS: We intended to implant a pulmonary artery (PA) reducer percutaneously between the native pulmonic valve and the pulmonary bifurcation. Immediately following its insertion, we planned to implant a balloon expandable stent inside the restriction to calibrate the banding. Sheep were sacrificed acutely (group 1, n=6) and after 1 month of follow-up (group 2, n=6), the reducer was implanted successfully in all animals. It allowed the PA diameter to be reduced from 25 to 10.5 mm. Bare stents were successfully delivered inside the reducer. No paraprosthetic leak was found by injecting contrast dye. After the insertion procedure, signs of intolerance to obstruction were present in all animals and prompted us to dilate the stents from 12 to 16 mm. One animal from group 1 died before a balloon dilatation could be achieved. In the animals from group 2, the mean systolic gradient was 19 and 34.8 mmHg, respectively, at early and late evaluation. CONCLUSION: Implantation of a PA reducer is possible in sheep, through a transcatheter approach allowing intravascular PAB. Miniaturization of the device is necessary to enlarge its use from adulthood to childhood.

Animals↗
PubMed2006

Presentation and prognosis of complete atrioventricular block in childhood, according to maternal antibody status.

OBJECTIVES: We sought to determine whether the presentation and prognosis of children with complete atrioventricular block (CAVB) were related to maternal antibody status. BACKGROUND: Comparative studies related to the presence or absence of maternal antibodies anti-SSB/La and anti-SSA/Ro are lacking in children with isolated complete CAVB. METHODS: From 1980 to 2004, we screened for maternal antibodies in 111 children <15 years old with CAVB. According to the presence (Ab+) or absence (Ab-) of antibodies, 2 groups of patients were retrospectively compared. RESULTS: The study group included 56 Ab+ and 55 Ab- patients with equal gender distribution. A total of 96% Ab+ patients were diagnosed in utero or within the first month, compared with 24% Ab- patients. Progression from incomplete to complete block was shown in 23 Ab- and 2 Ab+ patients. Echocardiography showed normal heart structures in Ab- patients, but 8 Ab+ patients had ostium secundum or ductus arteriosus. Pacemaker implantation was performed in 105 patients, and age at implantation was younger in the Ab+ group. At follow-up (age 9.7 +/- 6 years), all Ab- patients were alive with normal left ventricular function; dilated cardiomyopathy was diagnosed at diagnosis or during follow-up in 16 Ab+ patients, and 6 of 16 have died. CONCLUSIONS: Patients with antibody-mediated CAVB were diagnosed and underwent pacing earlier in life and had a more severe prognosis than Ab- patients because of a high risk of dilated cardiomyopathy. The absence of antibody suggests a different pathologic mechanism than autoimmunity, and the term congenital may be not appropriate in these cases.

Antibodies↗
PubMed2006

Expandable right ventricular-to-pulmonary artery conduit: an animal study.

This study was performed to assess a new vascular stent graft as an expandable valved conduit for right ventricular outflow tract (RVOT) reconstruction in sheep. Conduits were constructed by sewing an 18-mm valved conduit inside a stent. Crimped to 16 mm, they were implanted either under or without extracorporeal circulation in seven (group A) and in five (group B) sheep, respectively. Six weeks and 3 mo after their insertion, conduits were dilated intraluminally. A valved stent was implanted percutaneously into conduits before they were killed. Two animals from group A recovered normally, whereas five animals had a complicated postoperative course. In group B, one died acutely due to kinking of the conduit. Balloon dilatations were performed in all surviving animals. First dilatations had a slight impact on valvular function in all animals but one, whereas second dilatations led to significant PR in all. Transcatheter valve implantation was performed successfully. When animals were killed, no bleeding was found around the surgically implanted device. In conclusion, we designed a biologic valved conduit for RVOT reconstruction that can be dilated sequentially to follow animal growth. This new device can have tremendous applications in children with congenital heart diseases involving the RVOT.

Animals↗
PubMed2006

Neonatal surgical aortic commissurotomy: predictors of outcome and long-term results.

BACKGROUND: The objective of this study was to review our institutional experience concerning neonatal aortic commissurotomy and to identify predictors of outcome. METHODS: From January 1, 1990, to January 1, 2005, 65 neonates were referred for critical aortic stenosis. Among these 36 consecutive patients underwent surgical valvotomy by the same surgeon and 16 patients had balloon valvotomy. We examined clinical records to establish determinants of outcome and illustrate long-term results. RESULTS: In the surgical group 6 patients had nonstenotic parachute mitral valve, 6 had aortic coarctation, 13 had endocardial fibroelastosis; and 15 had depressed fractional shortening. In the balloon valvotomy group most infants had associated mitral stenosis (n = 7), small aortic annulus (n = 5), multiple anomalies (n = 2), endocardial fibroelastosis (n = 9), and depressed fractional shortening (n = 13). In the surgical group global mortality was 19%; 47% in infants with depressed fractional shortening and 0% in infants with normal fractional shortening. Mortality in the balloon valvotomy group was 56%. Low fractional shortening, low mean aortic gradient, endocardial fibroelastosis, and small aortic annulus were associated with fatal outcome. In the surgical group 6 patients needed Ross operation at a median interval of 4 years from commissurotomy. In the balloon valvotomy group 3 patients needed early mitral replacement and 5 aortic valve surgery. At a median follow-up of 6 years, all children are in New York Heart Association class I, all have a normal ventricular function, 2 have aortic restenosis, and 5 have at least moderate aortic incompetence. CONCLUSIONS: In a selected population of neonates with isolated aortic stenosis, surgical valvotomy offers an excellent long-term outcome to patients with a normokinetic left ventricle, while patients with a hypokinetic left ventricle have a poor outcome. Balloon valvotomy offers poor results when performed in patients with complex anomalies.

Aortic Valve Stenosis↗
PubMed2006

Off-label use of an adjustable gastric banding system for pulmonary artery banding.

BACKGROUND: Pulmonary artery banding is proposed as a first palliation in infants with complex congenital heart disease and high pulmonary blood flow. In addition, it may be used to retrain the left ventricle. Optimal tightening may be difficult to obtain, leading to reoperation. An implantable device for pulmonary artery banding with telemetric control was recently developed allowing for repeated adjustments, but it is presently limited to patients weighing less than 20 kg. In large animals, we tested an off-label adjustable gastric banding system for pulmonary artery banding. METHODS AND RESULTS: Fourteen ewes weighing 50 to 75 kg underwent implantation of the Lap-Band device (BioEnterics Corp, Santa Barbara, Calif) around the main pulmonary artery through a left thoracotomy. All had functional evaluation with progressive occlusion and opening of the device at implantation and every 2 weeks until sacrifice immediately after implantation (group 1, n = 8), at 1 month (group 2, n = 3), at 3 months (group 3, n = 3), or death. Invasive pressure measurements in the right ventricle and aorta were carried out each time. Devices were easily implanted in all animals. Progressive occlusion and reopening were possible in all animals during each time point. Two animals died of right heart failure related to excessive tightening of the band. Retrieval of the device without any major damage was possible in 12 of 14 animals. CONCLUSION: With this implantable device, we were able to adjust the pulmonary artery diameter in animals. Patients requiring left ventricle retraining and weighing more than 30 kg would benefit from the device's use in humans.

Animals↗
PubMed2006

Neonatal transcatheter closure of a large pulmonary arteriovenous fistula.

A congenital fistulous connection between the right pulmonary artery and the left atrium is a rare condition, resulting in early cyanosis and cardiac failure. These patients usually required urgent surgery. We present a neonate in whom we successfully closed such a large fistula via catheterization with an Amplatzer Duct Occluder, resulting in rapid clinical improvement, and obviating the need for surgical repair.

Arteriovenous Fistula↗
PubMed2005

Percutaneous pulmonary valve implantation in humans: results in 59 consecutive patients.

BACKGROUND: Right ventricular outflow tract (RVOT) reconstruction with valved conduits in infancy and childhood leads to reintervention for pulmonary regurgitation and stenosis in later life. METHODS AND RESULTS: Patients with pulmonary regurgitation with or without stenosis after repair of congenital heart disease had percutaneous pulmonary valve implantation (PPVI). Mortality, hemodynamic improvement, freedom from explantation, and subjective and objective changes in exercise tolerance were end points. PPVI was performed successfully in 58 patients, 32 male, with a median age of 16 years and median weight of 56 kg. The majority had a variant of tetralogy of Fallot (n=36), or transposition of the great arteries, ventricular septal defect with pulmonary stenosis (n=8). The right ventricular (RV) pressure (64.4+/-17.2 to 50.4+/-14 mm Hg, P<0.001), RVOT gradient (33+/-24.6 to 19.5+/-15.3, P<0.001), and pulmonary regurgitation (PR) (grade 2 of greater before, none greater than grade 2 after, P<0.001) decreased significantly after PPVI. MRI showed significant reduction in PR fraction (21+/-13% versus 3+/-4%, P<0.001) and in RV end-diastolic volume (EDV) (94+/-28 versus 82+/-24 mL.beat(-1).m(-2), P<0.001) and a significant increase in left ventricular EDV (64+/-12 versus 71+/-13 mL.beat(-1).m(-2), P=0.005) and effective RV stroke volume (37+/-7 versus 42+/-9 mL.beat(-1).m(-2), P=0.006) in 28 patients (age 19+/-8 years). A further 16 subjects, on metabolic exercise testing, showed significant improvement in VO2max (26+/-7 versus 29+/-6 mL.kg(-1).min(-1), P<0.001). There was no mortality. CONCLUSIONS: PPVI is feasible at low risk, with quantifiable improvement in MRI-defined ventricular parameters and pulmonary regurgitation, and results in subjective and objective improvement in exercise capacity.

Adolescent↗
PubMed2005

Steps toward the percutaneous replacement of atrioventricular valves an experimental study.

OBJECTIVES: The goal of this study was to develop a device for percutaneous replacement of the tricuspid valve in animals. BACKGROUND: Percutaneous valve replacement has recently been introduced, and early clinical experience has been reported. To date, this technique is limited to the replacement of pulmonary and aortic valves in selected patients. METHODS: A newly designed nitinol stent, forming two large disks separated by a cylinder with a diameter of 18 mm, was specially designed for the purpose of this study. An 18-mm bovine valve was mounted in the central part of the stent, and a polytetrafluoroethylene membrane was sutured onto the ventricular disk. Eight ewes were equally divided into two groups (group 1, acute study; group 2, killed at one month). RESULTS: Seven of eight devices were successfully delivered in the desired position. In one animal, the device was trapped in tricuspid cordae, leading to its incomplete opening. A significant paravalvular leak was noticed in one animal of group 2. Mean right atrial pressure increased from 5 to 7 mm Hg and did not change during the follow-up. At autopsy, examination confirmed the good position of devices in successfully implanted animals. CONCLUSIONS: Implantation of a semi-lunar valve in the tricuspid position is possible in ewes through a transcatheter approach. A disk-based nitinol stent is needed to allow valve implantation in the atrioventricular position. These studies open new perspectives into tricuspid as well as mitral valve replacement.

Alloys↗
PubMed2005

New insights in minimally invasive valve replacement: description of a cooperative approach for the off-pump replacement of mitral valves.

AIMS: The aim of the present study was to evaluate whether off-pump mini-invasive mitral valve replacement is possible after prior bioprosthetic mitral valve replacement in animals. METHODS AND RESULTS: To validate this concept for off-pump redo mitral valve insertion, we first replaced surgically mitral valves of six sheep under extracorporeal circulation using a Mosaïc valve. Prior to its insertion, we added a radio-opaque ring on its base to enhance its visualization under fluoroscopy. A bovine jugular valve mounted into a stent was then inserted off-pump through an opening of the atrial wall. Mitral valves were replaced successfully in all animals. Following the surgical valve insertion, mean left atrium and left ventricular end-diastolic pressures were 38 (22-42) and 18.8 mmHg (13-22), respectively. Angiography showed perfectly functioning valves, no subaortic valve obstruction, and a mild paravalvular leak in one animal. In one animal, we were unable to control the bleeding from the atrial opening. In this case, trans-atrial valvulation was not attempted. The off-pump valvular implantation was successful in the other five sheep. Haemodynamic data did not change after the insertion of valved stents. Implanted valves were all competent. The animal with the better haemodynamics was kept alive and is still alive 3 months after implantation. CONCLUSION: Surgically implanted bioprosthetic valves provide excellent support for off-pump insertion of a valved stent. Further experiments are necessary, in particular with appropriate valve size, before considering this approach for percutaneous mitral valvular replacement in patients with a dysfunctional bioprosthesis.

Animals↗
PubMed2005

Transhepatic ultrasound-guided cardiac catheterization in the fetal lamb: a new approach for cardiac interventions in fetuses.

BACKGROUND: Percutaneous transventricular and fetoscopic umbilical catheterization have been applied to animal and human fetuses. These methods have a high rate of failure and complications. Here, we propose an alternative route for anterograde echocardiography-guided cardiac catheterization through a transhepatic approach of the intra-abdominal vessels in the fetal lamb. METHODS AND RESULTS: After exteriorization of the uterus in 12 pregnant ewes between 118 to 122 days' gestation, a 4F sheath mounted over a 1.2-mm needle was placed into the intra-abdominal portion of the umbilical vein (n=2) and into the subdiaphragmatic portion of the inferior vena cava via a transhepatic approach (n=10) under ultrasound guidance. In the first 2 animals using a transumbilical approach, it was impossible to reach the heart through the ductus venosus. In the next 10 animals, using a conventional technique, echocardiography-guided catheterization of the 4 chambers was performed in the all fetuses, atrial or ventricular pacing in 6 fetuses, and ballooning of the pulmonary valve in 9 of 10 fetuses. Among the 10 fetuses catheterized through the transhepatic approach, 2 were euthanized immediately after the procedure to evaluate intraperitoneal bleeding (23 and 29 mL, respectively), and 3 died after the procedure (1 of major bleeding and 2 deaths related to balloon catheter manipulation). Finally, 5 were delivered vaginally after an uneventful pregnancy, and autopsy at day 5 did not show significant liver, vascular, or cardiac injury. CONCLUSIONS: Echocardiography-guided fetal cardiac catheterization through a transhepatic approach is feasible and provides an interesting alternative approach for human fetal cardiac interventions.

Animals↗
PubMed2005

Off-pump replacement of the pulmonary valve in large right ventricular outflow tracts: a hybrid approach.

BACKGROUND: Percutaneous pulmonary valve replacement has recently been introduced and is under investigation in humans. This technique is, however, limited to patients with a right ventricular outflow tract that does not exceed 22 mm in diameter. We report our experience of off-pump pulmonary valve replacement using a hybrid approach in animals with large right ventricular outflow tracts. METHODS: Eight ewes were included in the protocol and were equally divided into 2 groups. A left thoracotomy was first performed, and the main pulmonary artery was banded by using 2 radiopaque rings with a diameter of 18 mm that allowed for further pulmonary valve replacement. We then intended to implant a valved stent either percutaneously (group 1) or through a transventricular approach (group 2). All animals were killed after valve implantation. The operation allowed the pulmonary diameter to be reduced from 30 to 17.6 mm. RESULTS: The right ventricular pressure did not significantly increase after reduction of the pulmonary artery diameter (25 vs 36 mm Hg). Subsequent pulmonary valve replacement through a percutaneous or a transventricular approach was always possible without any requirement for extracorporeal circulation. All devices were successfully delivered inside the pulmonary artery banding and were functioning perfectly at early evaluation. CONCLUSIONS: Implantation of a pulmonary valve is possible in ewes through a hybrid approach when the right ventricular outflow tract exceeds 22 mm in diameter. This involves both surgeons and interventionists and allows for a staged procedure in which the valvulation is performed percutaneously or, for a combined hybrid approach, in which the valve is implanted off pump transventricularly during the same operation.

Animals↗
PubMed2005

Complications of paediatric interventional catheterisation: an analysis of risk factors.

OBJECTIVES: To identify predictive factors of complications occurring during paediatric interventional catheterisation. BACKGROUND: Interventional paediatric catheterisation is still burdened by a substantial risk. Risk factors, however, have rarely been investigated. METHODS: We analysed prospectively 1,022 interventional procedures performed over a period of 8 years, excluding 260 procedures for atrial septostomy. We considered several patient-related variables, specifically age, weight, and gender, type of procedure, times required for fluoroscopy and the overall procedure, technical challenge, and the severity of the clinical condition. We also analysed variables linked to the environment, specifically the date of the examination, whether the operator remained in training, the novelty of the material, any breakdown in the installation, and errors made by the operator. We classified complications as those without clinical consequence, those which proved lethal, those requiring cardiopulmonary resuscitation, elective or emergency surgery, hospitalisation in the intensive care unit, and those leading to recatheterisation. RESULTS: Our average incidence of complications was 4.1 per cent, which did not change significantly during the period of study. Of the patients, 4 died, 7 needed urgent surgery, 5 elective surgery, 3 hospitalisation in intensive care unit, and 8 recatheterisation. Independent risk factors for complications were technical challenge, critical clinical condition, operator in training, operator error, and breakdown of the installation. Young age was not associated with a higher risk of complications. Patients in whom no cause for complication could be found, either related to their own features or the environment, had a risk of complication of 1.4 per cent (95 per cent confidence intervals from 0.7 to 2.5 per cent). CONCLUSIONS: Our data show that variables relating either to the patient or the environment of catheterisation are associated with an increased risk of procedural complications. Knowledge of the risk factors can improve the odds of paediatric interventional catheterisation.

Adolescent↗
PubMed2004

Surgical reconstruction of occluded pulmonary arteries in patients with congenital heart disease: effects on pulmonary artery growth.

BACKGROUND: This study was undertaken to determine outcomes and best strategies for treatment of occluded pulmonary arteries in patients with congenital heart disease. METHODS AND RESULTS: Between 1998 and 2002, occlusion of a previously patent pulmonary artery was established in 23 patients. Data were obtained retrospectively. Diagnoses were pulmonary atresia and ventricular septal defect in 11, tetralogy of Fallot in 6, and other forms of pulmonary stenosis or atresia in 6. Median age and weight at diagnosis were 9 years (range, 6 days to 43 years) and 24 kg (range, 2.6 to 60 kg). Fourteen patients had had a previous surgery. The occluded pulmonary artery was visualized at angiography by wedge injection or injection into the collateral circulation. The left pulmonary artery was occluded in 20 patients and the right pulmonary artery in 3. Criteria for reconstruction were estimated duration of occlusion <6 months and ratio of occluded to contralateral artery >0.2. Twelve patients fulfilled these criteria and underwent pulmonary artery reconstruction at a mean interval of 2 months (range, 6 days to 6 months) from evidence of occlusion. Six patients had pericardial patch reconstruction, 3 terminoterminal anastomosis, 2 thrombectomy, and 1 a Blalock-Taussig shunt. There was 1 late death. At a median follow-up of 4 years (2 months to 5 years), all patients underwent cardiac catheterization: in 8 patients the reconstructed artery was patent, in 3 reoccluded. Hypoplasia of the occluded artery was reversed in 6 patients. CONCLUSIONS: Our data show that in selected patients, reconstruction of an occluded pulmonary artery can restore pulmonary vascularization and reverse hypoplasia. Strict surveillance is mandatory to prevent pulmonary artery loss.

Adolescent↗
PubMed2004

Percutaneous pulmonary valve replacement in a large right ventricular outflow tract: an experimental study.

OBJECTIVES: We report our initial experience with percutaneous pulmonary valve replacement in animals with large pulmonary trunks, using a modified percutaneous approach. BACKGROUND: Percutaneous pulmonary valve replacement has recently been introduced, and early clinical experience has been reported. This technique is presently limited to patients with a right ventricular outflow tract no bigger than 22 mm in diameter. METHODS: In seven animals (groups 1 and 3), we implanted a newly designed nitinol stent in the shape of a conduit with a central restriction of its diameter, containing an 18-mm bovine valve, as a one-step procedure. The animals in groups 1 and 3 were sacrificed after valve implantation and after two-month follow-up, respectively. In the second group (n = 3), we expected to percutaneously reduce the diameter of the pulmonary artery. Eight weeks later, we implanted an 18-mm valve mounted in a balloon-expandable stent. These animals were sacrificed after valve implantation. RESULTS: Eight of 10 devices were successfully delivered and were functioning perfectly at the initial evaluation and after two months. We failed to cross the tricuspid valve in two cases. The downsize mechanism allowed the pulmonary diameter to be reduced from 30 to 18 mm, without an impact on right ventricular function in any of the animals. CONCLUSIONS: Non-surgical implantation of a pulmonary valve is possible in ewes with all types of pulmonary trunk, regardless of its size. A "downsize" stent is needed to allow valve implantation in a large trunk. Further refinements will make this technique feasible in humans.

Animals↗
PubMed2004

Is percutaneous implantation of a bovine venous valve in the inferior vena cava a reliable technique to treat chronic venous insufficiency syndrome?

BACKGROUND: To evaluate the feasibility and safety of percutaneous implantation of a balloon-expandable valved stent in the inferior vena cava. MATERIAL/METHODS: A valve harvested from a bovine jugular vein, preserved in glutaraldehyde and mounted in a stent, was evaluated in animals. Six lambs, weighing 30 to 40 kg, were included in the study. Under general anesthesia, a valved stent with its 18-Fr delivery system was inserted through the right jugular vein, advanced, and delivered in the inferior vena cava. Hemodynamic and angiographic evaluations were performed prior to, immediately after, and two months after implantation. RESULTS: All valved stents were successfully implanted in the desired position. No early or late migration of the stent was noted in any animal. All valves were perfectly competent at the time of implantation. At 2 months, none of the valves were functional. The inferior vena cava was occluded at the site of valve insertion and collateral circulation was present in all animals. At autopsy, the valved stent was completely occluded. CONCLUSIONS: Valve implantation is feasible in the venous system through a percutaneous approach. The function of this valve in that position is limited by the absence of a high pressure gradient. Animal models and improvements in the device are mandatory before considering this technique as a reliable procedure to treat chronic venous insufficiency syndrome in humans.

Angiography↗
PubMed2004

Emergency trans-oesophageal ventricular pacing in a child.

We report our experience with an 8-year-old boy with complete atrioventricular block and syncopal bradycardia who required urgent pacing. Each attempt to cross the tricuspid valve with a femoral lead triggered ventricular standstill, followed by fibrillation, and pacing through the coronary sinus failed. Successful ventricular pacing was finally achieved through the oesophagus, allowing subsequent implantation of a transvenous pacemaker.

Bradycardia↗