Implantation In Infants Research Articles

Research progress on auditory neuropathy spectrum disorder and cochlear implantation in infants and young children

Auditory neuropathy is a disorder characterized by absent or severely abnormal auditory brainstem response (ABR) with intact outer hair cell function, as evidenced by the presence of evoked otoacoustic emissions and/or cochlear microphonics. Unlike patients with sensory hearing loss who show clinical evidence of impaired outer hair cell function. For ANSD patients, clinical rehabilitation is mainly limited to hearing aid wearing and cochlear implantation. However, the effect of cochlear implantation for ANSD patients may be difference. The outcome of cochlear implantation is related to the lesion location, the age of implantation and the diameter of cochlear nerve.

First follow-up of a breakable stent for implantation in infants dedicated for a life-long stay.

The use of conventional metal stents in infants is severely limited by subsequent somatic growth. The use of a breakable balloon expandable stent (BS) designed for initial implant at small diameters but with properties that allow unlimited dilation in line with growth has potential advantages in this patient group. This study reports our experience with this stent between 2010 and 2014. A total of 17 BS were implanted in 14 infants (mean age 4.8 months). All but one stent was placed into the aorta to treat coarctation. All implantations were successful and initial gradients dropped from a mean of 25-6 mm Hg (range from 1-50 down to 0-24 mm Hg). Mean follow-up was 3.3 years (range 5 days to 7 years) with a total cumulative follow-up of 46.7 patient years. Stent redilation was performed a median of 2.5 times (range 0-5). Sixteen stents in 13 patients remain in place. Following redilation beyond 10 mm, circumferential integrity of the BS was lost in 10 patients. No further stent implantation or related surgery was necessary. A 3 mm dissection occurred in one patient after redilation. The BS performed well in terms of relief of stenosis and could be successfully dilated during the phase of the infants' most rapid growth. Mild intimal proliferation occurred in some patients early after implantation. In the course of the stepwise redilations and growth adjustments, both, planned longitudinal and transverse fractures occurred without allowing a collapse of the stented area.

Initial in vitro testing of a paediatric continuous-flow total artificial heart.

Mechanical circulatory support has become standard therapy for adult patients with end-stage heart failure; however, in paediatric patients with congenital heart disease, the options for chronic mechanical circulatory support are limited to paracorporeal devices or off-label use of devices intended for implantation in adults. Congenital heart disease and cardiomyopathy often involve both the left and right ventricles; in such cases, heart transplantation, a biventricular assist device or a total artificial heart is needed to adequately sustain both pulmonary and systemic circulations. We aimed to evaluate the in vitro performance of the initial prototype of our paediatric continuous-flow total artificial heart. The paediatric continuous-flow total artificial heart pump was downsized from the adult continuous-flow total artificial heart configuration by a scale factor of 0.70 (1/3 of total volume) to enable implantation in infants. System performance of this prototype was evaluated using the continuous-flow total artificial heart mock loop set to mimic paediatric circulation. We generated maps of pump performance and atrial pressure differences over a wide range of systemic vascular resistance/pulmonary vascular resistance and pump speeds. Performance data indicated left pump flow range of 0.4-4.7 l/min at 100 mmHg delta pressure. The left/right atrial pressure difference was maintained within ±5 mmHg with systemic vascular resistance/pulmonary vascular resistance ratios between 1.4 and 35, with/without pump speed modulation, verifying expected passive self-regulation of atrial pressure balance. The paediatric continuous-flow total artificial heart prototype met design requirements for self-regulation and performance; in vivo pump performance studies are ongoing.

Long-term outcomes following primary intraocular lens implantation in infants younger than 6 months

Purpose:To study the long-term safety profile and visual outcomes of primary intraocular lens (IOL) implantation in infants <6 months of age.Methods:This was a retrospective observational study conducted at a tertiary eye care center in South India. Infants under 6 months meeting the selection criteria who underwent cataract surgery (lens aspiration, primary posterior capsulorhexis, and anterior vitrectomy) with primary IOL implantation between January 2008 and December 2011 and minimum 3-year follow-up were included. Patient demographics, serial refractions, visual acuity, complications, and associated amblyopia/strabismus were reviewed. Visual acuity, myopic shift, and complications were the outcome measures.Results:Sixty-nine eyes of 38 infants (31 bilateral; mean age: 4.6 months) were reviewed. Mean follow-up was 51 months (range: 36–84). Median logMAR best-corrected visual acuity at the final visit was 0.74 (interquartile range [IQR]: 0.50–0.98) in eyes with bilateral cataracts and 0.87 (IQR: 0.60–1.14) in eyes with unilateral cataracts with an average myopic shift of 6.7 diopters over 4.2 years. Most common postoperative complication was visual axis opacification (VAO) (13 eyes, 18%), necessitating membranectomy followed by pigmentary IOL deposits (11 eyes, 15%), and IOL decentration and glaucoma in four eyes each (5.6%). Mixed linear effect model found no significant association of age, gender, laterality, and postoperative complications with final visual acuity (P ≥ 0.05). Eyes with unilateral cataracts had a greater myopic shift than bilateral cases (P = 0.03).Conclusion:Primary IOL implantation in infants <6 months is reasonably safe in appropriately selected infants. VAO was the most common postoperative complication, and a large myopic shift was observed.

Long-term results of primary intraocular lens implantation in infants: Our experience

Objective: The main objective of this study is to analyze the long-term outcome in children who underwent cataract surgery for congenital cataract with intraocular lens (IOL) implantation

Cochlear implantation in infants below 12 months of age.

ObjectivesTo provide safety and efficacy data on infants implanted below 12 months of age.MethodsWith the wide application of newborn hearing screening programs, infants with deafness are being identified at birth. When a hearing aid trial fails, cochlear implantation is the only option to restore hearing. Mounting evidence suggests that age at implantation is a strong predictor of language outcomes. Using the minimally invasive surgical technique we have employed for nearly two decades, a limited clinical trial was initiated in the year 2000 because this age limitation fell outside of FDA guidelines. The infants were initially assessed using the preferential listening paradigm to confirm that they could learn associations between speech sounds and objects. Sufficient time was allowed to pass to administer more traditional language measures.ResultsNo surgical or anesthetic complications occurred in this group of infants. The pattern of listening skill development mirrored that seen in normal hearing infants. Long-term language assessments using the Peabody Picture Vocabulary Test (PPVT) and other measures have demonstrated that many of infants achieved age appropriate language skills.ConclusionCochlear implantation in children less than 12 months of age is safe and efficacious as demonstrated by long-term PPVT language data.

Primary intraocular lens implantation in infants less than 6 months: a long term outcome

Intraocular lens (IOL) implantation in infants still remains challenging despite advances in pediatric cataract surgery. We aimed to study the long-term safety profile and visual outcomes of primary IOL implantation in infants less than 6 months of age.

Anisometropia at Age 5 Years After Unilateral Intraocular Lens Implantation During Infancy in the Infant Aphakia Treatment Study

To report the prevalence of anisometropia at age 5 years after unilateral intraocular lens (IOL) implantation in infants. Prospective randomized clinical trial. Fifty-seven infants in the Infant Aphakia Treatment Study (IATS) with a unilateral cataract were randomized to IOL implantation with an initial targeted postoperative refractive error of either+8 diopters (D) (infants 28 to <48days of age) or+6 D (infants 48-210days of age). Anisometropia was calculated at age 5 years. Six patients were excluded from the analyses. Median age at cataract surgery was 2.2months (interquartile range [IQR], 1.2, 3.5months). The mean age at the age 5 years follow-up visit was 5.0 ± 0.1 years (range, 4.9-5.4 years). The median refractive error at the age 5 years visit of the treated eyes was-2.25 D (IQR-5.13,+0.88 D) and of the fellow eyes+1.50 D (IQR+0.88,+2.25). Median anisometropia was-3.50 D (IQR-8.25,-0.88 D); range-19.63 to+2.75 D. Patients with glaucoma in the treated eye (n= 9) had greater anisometropia (glaucoma, median-8.25 D; IQR-11.38,-5.25 D vs no glaucoma median-2.75; IQR-6.38,-0.75 D; P=.005). The majority of pseudophakic eyes had significant anisometropia at age 5 years. Anisometropia was greater in patients that developed glaucoma. Variability in eye growth and myopic shift continue to make refractive outcomes challenging for IOL implantation during infancy.

Visual outcomes and complications of cataract surgery with primary implantation in infants

To describe the visual results and postoperative complications of cataract surgery with primary intraocular lens (IOL) implantation performed in infants and to determine possible predictive factors related to poor visual outcome. A retrospective consecutive case series of cataract surgeries with primary IOL implantation in infants was performed. Visual outcome and postoperative complications were recorded. A final visual acuity>0.5 logMAR was considered as a poor visual outcome. Sixty-one consecutive procedures were evaluated in 43infants. Eighteen infants (42%) had bilateral cataract surgery and 25(58%) had monocular surgery. The median age at primary surgery was 5.7months (range: 4weeks-24months). The median follow-up was 47months (range: 14-60months). The median best-corrected visual acuity in logarithm of the minimum angle of resolution (logMAR) at the last follow-up examination was 1.00 in the case of unilateral surgery and 0.40 in the case of bilateral surgery. The overall visual result in all eyes was 0.50logMAR. A better visual result was achieved when the infants were younger than 6months or older than 12months of age when surgery was performed. Opacification in the visual axis requiring secondary surgery occurred in 54% of the eyes (33/61). Postoperative inflammation occurred in 41% of the eyes (25/61) but was not associated with poor visual outcome (P=0.39). Glaucoma affected 11.5% of the eyes (7/61) and was significantly associated with poorer visual function (OR: 15.36, 95% CI 1.02-230.35, P=0.05). Compared with the unilateral cataract group, the OR of poor visual acuity was 0.06 (95% CI 0.01-0.35, P<0.01) in the bilateral cataract group. No statistical association was observed between final visual acuity>0.5 logMAR and leukocoria at time of diagnosis, IOL-related complications and postoperative strabismus. Primary IOL implantation is associated with an overall satisfactory visual outcome, especially when surgery is performed before 6months or after 12months of age and in bilateral cases. Glaucoma is the main complication associated with poor visual outcome.

Concept of an expandable cardiac valve for surgical implantation in infants and children

BackgroundOptions for cardiac valve replacement in children are limited to fixed-diameter prostheses that do not accommodate for somatic growth. An externally stented bovine jugular vein graft has been modified for surgical valve replacement in pediatric patients, with the intention of subsequent valve expansion in the catheterization laboratory as the child grows. MethodsPediatric patients at a single institution who underwent surgical implantation of an expandable bovine jugular vein valve between 2010 and 2014 were reviewed retrospectively. Forty-two patients underwent implantation at median age of 10 months (range, 3 weeks to 5.8 years) in aortic, mitral, pulmonary, or tricuspid positions. Numerous techniques for valve modification and implantation were used. ResultsThe valve was competent with low gradient acutely postoperatively in all patients. Eight patients experienced central or paravalvular deterioration, and 7 required reoperation for valve-related adverse outcomes. Twenty patients underwent at least one previous valve repair or replacement. Twenty patients underwent 32 episodes of catheter-based balloon expansion of the valve, exhibiting a significant decrease in median gradient from 12 mm Hg to 8 mm Hg (P < .001) with no significant increase in grade of regurgitation. At 12 months after implantation, Kaplan-Meier analysis indicated that 88% would be expected to be free from reoperation (95% confidence interval, 78%-98%). A total of 6 deaths occurred, 3 before discharge and 3 late. ConclusionsA surgically implanted externally reinforced bovine jugular vein demonstrates acceptable short-term function and is amenable to catheter-based enlargement as the child grows. Modification of valve design and implantation techniques are necessary to reduce perivalvular complications.

Refractive error and anisometropia after unilateral intraocular lens implantation in infants under 7 months of age—results at 5 years of age from the Infant Aphakia Treatment Study (IATS)

Refractive error and anisometropia after unilateral intraocular lens implantation in infants under 7 months of age—results at 5 years of age from the Infant Aphakia Treatment Study (IATS)

Outcome of primary intraocular lens implantation in infants: Complications and rates of additional surgery

To study the requirement of additional surgery and adverse events in infants having primary intraocular lens (IOL) implantation. Tertiary care institute, Chandigarh, India. Prospective observational noncomparative case series. Infants who had phacoaspiration, primary posterior capsulotomy, anterior vitrectomy, and primary IOL implantation were evaluated for complications and the need for additional surgery over a 3-year period. The main outcome measures were the rate of complications, adverse events, and need for additional surgery. Sixty infants (100 eyes) with a mean age of 7.13months±2.32 (SD) (range 3 to 12months) were studied. The mean follow-up was 41.2±3.5months. Indication of additional surgery included visual axis opacification in 13 eyes, pupillary membrane/IOL decentration in 4eyes, and iris prolapse in 4 eyes. Adverse events included pigment on the IOL in 14 eyes and iridolenticular adhesions in 9 eyes. Ocular hypertension was observed in 2 eyes. The IOL was placed in sulcus or by optic capture in 14 eyes. There was no difference in additional surgery and adverse events between infants aged 6months or younger versus those older than 6months (P=.734). There was a low incidence of adverse events and additional surgery requirement in infants who had cataract surgery with primary IOL implantation. None of the authors has a financial or proprietary interest in any material or method mentioned.

Contemporary surgical issues in paediatric cochlear implantation

Objective: To review the contemporary surgical issues in paediatric cochlear implantation (CI) based on published evidence. Design: Narrative literature review. Results: Surgical challenges in paediatric CI are discussed, with respect to post meningitic labyrinthitis ossificans; cochlear malformation; cochlear implantation in infants; auditory neuropathy and cochlear nerve deficiency; bilateral cochlear implantation; hearing preservation; otitis media; and device failure. Conclusion: Early CI is recommended if bacterial meningitis causes profound sensorineural hearing loss (SNHL). CI in cochleovestibular malformation requires pre-operative imaging to plan surgical technique, choice of electrode, and to anticipate complication. Children with congenital severe to profound SNHL should undergo early bilateral simultaneous implantation, preferably before 12 months of age, except those with auditory neuropathy spectrum disorder who should be implanted after one year. Soft surgical technique should be deployed in an attempt to preserve any residual hearing. Otitis media with effusion is not a contraindication to cochlear implantation, but active or recurrent acute otitis media requires resolution of infection with grommet insertion pre-operatively. Device failure in CI recipients requires a stepwise audiological, medical, radiological, and device integrity assessment to determine the need for reimplantation.

Long-term outcome of transvenous pacemaker implantation in infants: a retrospective cohort study.

Evaluation of long-term outcome of transvenous pacemaker (PM) implantation in infants. A retrospective analysis of all transvenous PM implantations in infants <10 kg between September 1997 and October 2001 was made. Indications for PM implantation, age at implantation, and determinants of long-term outcome including cardiac function, PM function, and PM (system) complications were noted. Seven patients underwent transvenous VVI(R) PM implantation. Median age at implantation was 3 days (range: 1 day to 14 months), median weight 3.5 kg (range: 2.3-8.7 kg), and median follow-up 14 years (range: 12.3-16.3 years). Pacemaker indications were congenital complete atrioventricular block (n = 4), long QT syndrome with heart block (n = 2), and post-operative complete atrioventricular block with sinus node dysfunction (n = 1). No procedural complications were noted. Today all patients are alive and symptom free with good PM and cardiac function. Two patients underwent PM generator relocation for imminent skin necrosis and skin traction. Two patients suffered from asymptomatic left subclavian vein occlusion and developed thrombosis on the PM electrode. Three patients were converted to an epicardial PM system, due to atrial perforation after upgrading procedure (n = 1), syncope with need for implantable cardioverter defibrillator implantation (n = 1), and systolic dysfunction with development of dilated cardiomyopathy, which normalized under cardiac resynchronization therapy pacing (n = 1). Two patients needed atrioventricular (AV) valve repair for severe insufficiency. Two patients underwent repositioning of dysfunctional PM leads. In five patients, transvenous leads were removed. Indications were elective lead replacement (n = 1), atrial perforation (n = 1), and switch to an epicardial system (n = 3). Transvenous PM implantation in infants (<10 kg) is associated with a high incidence of vascular occlusion, thrombosis, and severe atrioventricular valve regurgitation during long-term follow-up. We advocate an epicardial approach for PM implantation in small children.

Complications in the First 5 Years Following Cataract Surgery in Infants With and Without Intraocular Lens Implantation in the Infant Aphakia Treatment Study

To compare rates and severity of complications between infants undergoing cataract surgery with and without intraocular lens (IOL) implantation. Prospective randomized clinical trial. A total of 114 infants were enrolled in the Infant Aphakia Treatment Study, a randomized, multi-center (12) clinical trial comparing the treatment of unilateral aphakia in patients under 7 months of age with a primary IOL implant or contact lens. The rate, character, and severity of intraoperative complications, adverse events, and additional intraocular surgeries during the first 5 postoperative years in the 2 groups were examined. There were more patients with intraoperative complications (28% vs 11%, P = .031), adverse events (81% vs 56%, P = .008), and more additional intraocular surgeries (72% vs 16%, P < .0001) in the IOL group than in the contact lens group. However, the number of patients with adverse events in the contact lens group increased (15 to 24) in postoperative years 2-5 compared to the first postoperative year, while it decreased (44 to 14) in years 2-5 compared to the first postoperative year in the IOL group. If only one half of the patients in the contact lens (aphakic) group eventually undergo secondary IOL implantation, the number of additional intraocular surgeries in the 2 groups will be approximately equal. The increased rate of complications, adverse events, and additional intraocular surgeries associated with IOL implantation in infants <7 months of age militates toward leaving babies aphakic if it is considered likely that the family will be successful with contact lens correction.

Speech-evoked cortical auditory responses in children with normal hearing

Cortical auditory-evoked potentials (CAEPs), an objective measure of human speech encoding in individuals with normal or impaired auditory systems, can be used to assess the outcomes of hearing aids and cochlear implants in infants, or in young children who cannot co-operate for behavioural speech discrimination testing. The current study aimed to determine whether naturally produced speech stimuli /m/, /g/ and /t/ evoke distinct CAEP response patterns that can be reliably recorded and differentiated, based on their spectral information and whether the CAEP could be an electrophysiological measure to differentiate between these speech sounds. CAEPs were recorded from 18 school-aged children with normal hearing, tested in two groups: younger (5 - 7 years) and older children (8 - 12 years). Cortical responses differed in their P1 and N2 latencies and amplitudes in response to /m/, /g/ and /t/ sounds (from low-, mid- and high-frequency regions, respectively). The largest amplitude of the P1 and N2 component was for /g/ and the smallest was for /t/. The P1 latency in both age groups did not show any significant difference between these speech sounds. The N2 latency showed a significant change in the younger group but not in the older group. The N2 latency of the speech sound /g/ was always noted earlier in both groups. This study demonstrates that spectrally different speech sounds are encoded differentially at the cortical level, and evoke distinct CAEP response patterns. CAEP latencies and amplitudes may provide an objective indication that spectrally different speech sounds are encoded differently at the cortical level.

The use of contact lenses following intra-ocular lens (IOL) implantation in infants born with congenital cataracts

Purpose: Congenital cataracts are a major cause of childhood blindness due to deprivation amblyopia leading to loss of visual function and lifelong visual impairment. Advances in surgical techniques mean that infants can be fitted with an IOL at the time of cataract removal, ideally less than 10 weeks of age. They tend to be left hypermetropic to allow for axial elongation. This residual hypermetropia can be managed successfully with contact lenses, particularly useful in unilateral cataract. This retrospective audit aimed to determine the type and parameters of contact lenses used to achieve optimum fitting together with the length of time lenses were required dependent upon the rate of myopic shift.

Surgical techniques for implanting implantable cardioverter defibrillators in children and infants

Implantable cardioverter defibrillators (ICDs) are now being used in children. ICDs can be used to prevent sudden cardiac death caused by not only congenital heart defects, but also various non-structural diseases, such as long QT syndrome. However, a standard implantation technique for children, especially infants, has not yet been established. As the surgical implantation in infants is not amenable to transvenous lead placement, it was necessary to choose from epicardial, subcutaneous and pericardial ICD systems. However, many of these systems are associated with high rates of late complications. Lead fracture, insulation breakage, migration, buckling or crinkling of the patch lead and constrictive pericarditis have been reported as the most common lead-related complications. An increase in the defibrillation threshold is another issue that must be considered when using an ICD in a child or infant. Further studies on the outcomes, psychosomatic impact and other specific complications in the pediatric population need to be considered. The clinical use of ICDs in infants is still limited. Therefore, it is important to have many surgical options available so that the treatment can be custom-tailored to suit individual patients.

Results of congenital cataract surgery with and without intraocular lens implantation in infants and children

Operations for congenital cataract in children in the past had resulted in aphakia. Improvement in surgical tools and techniques as well as in intraocular lens (IOL) implantation has led to correction of the aphakia by IOL implantation. We report the outcome of cataract surgery with and without IOL on these children in our institution between 1991-2008. In this retrospective cohort study, the medical records of all children who underwent surgery for congenital cataract were reviewed. The final study group included 144 children (218 eyes). Postoperative visual acuity (VA) was tested either by Teller Acuity Cards (in preverbal children) or by the Snellen chart. Data on VA status and postoperative complications were retrieved. Patients with bilateral cataract had better postoperative VA than patients with unilateral cataract (logMAR 0.559 ± 0.455 vs. 0.919 ± 0.685, respectively, P < 0.001). Children who underwent IOL implantation had better postoperative VA than those who did not, but the type of surgery had no significant effect after correction for the child's age at surgery (P = 0.346). Secondary cataract occurred more frequently in the extra-capsular cataract extraction (ECCE) + IOL implantation group than in the ECCE only group (20.6 % vs. 8.3 %, respectively, P = 0.018). Patients with bilateral cataract had better postoperative VA compared with those with unilateral cataract. The type of surgery had no effect on final VA, but there was a higher rate of secondary cataract in the ECCE + IOL patients compared to the ECCE only patients.

Educational paper

Congenital cataract is the commonest worldwide cause of lifelong visual loss in children. Although congenital cataracts have a diverse aetiology, in many children, a cause is not identified; however, autosomal dominant inheritance is commonly seen. Early diagnosis either on the post-natal ward or in the community is important because appropriate intervention can result in good levels of visual function. However, visual outcome is largely dependent on the timing of surgery when dense cataracts are present. Good outcomes have been reported in children undergoing surgery before 6 weeks of age in children with unilateral cataract and before 10 weeks of age in bilateral cases. Placement of an artificial intraocular lens implant after removal of the cataract has become established practice in children over 2 years of age. There remains debate over the safety and predictability of intraocular lens implantation in infants. Despite early surgery and aggressive optical rehabilitation, children may still develop deprivation amblyopia, nystagmus, strabismus, and glaucoma. The diagnosis and management of congenital cataracts has improved substantially over the past 30 years with a concurrent improvement in outcomes for affected children. Many aspects of the pre-, intra-, and postoperative management of these patients continue to be refined, highlighting the need for good quality data and prospective collaborative studies in this field.