Radiofrequency Modification for Inducible and Suspected Pediatric Atrioventricular Nodal Reentry Tachycardia

Introduction: AV Node Reentry Tachycardia (AVNRT) is the second most common supraventricular tachycardia (SVT) undergoing pediatric radiofrequency ablation behind accessory pathway reentry tachycardias. AVNRT can be difficult to induce during electrophysiology study (EPS) and dual atrioventricular nodal (AVN) pathways physiology may not be demonstrated in young patients.Purpose: This report is the largest single center long term pediatric experience of radiofrequency modification of slow AVN input fibers for inducible or suspected (non-inducible) AVNRT.Results: One hundred thirty-two patients underwent slow input AVN modification from 1993 to 2002. The mean patient age was 13.7 years (4–20 yrs) with 62M/70F. Outpatient tachycardia was documented by ambulatory monitoring in all patients. AVNRT was induced in 98/132 patients during EPS (group A) with mean SVT cycle length of 324 msec (230–570 msec). Initial AVN modification (group A) was successful in 97/98 patients (99%). During 34/132 EPS, AVNRT was non-inducible; dual AVN physiology was present in 19/34 (group B), and 15/34 did not show evidence for dual AVN physiology (group C). These 34 patients underwent empiric AVN modification following discussion with patients’ families. Freedom of recurrence from SVT at 1 year was 96% for group A (94/98), 89% (17/19) for group B and 93% (14/15) for group C. 1 major and 6 minor complications occurred.Conclusions: AVN modification for AVNRT can be performed safely and effectively in pediatric patients with good long-term results. Empiric slow pathway AVN modification for non-inducible SVT results in a high rate of freedom from recurrence of tachycardia.     

Exogenous trauma simulating perifollicular fibromas

The patient is a 63-year-old woman who presented to her dermatologist for the removal of two nevi near her mouth. Histologic examination revealed melanocytic nevi showing maturation with dermal descent. Within the dermis, adjacent to these nevoid cells, were multiple large hair follicles that were surrounded by dense fibrosis. The fibrous sheaths contained thickened, dense collagen bundles and were well circumscribed, resembling perifollicular fibromas. Further discussion with the patient and the dermatologist revealed that the patient had "plucked" hair from these nevi. We, therefore, believe that the perifollicular fibrosis that we observed is secondary to trauma. We present this case to remind all that post-traumatic events can simulate perifollicular fibromas and that the erroneous diagnosis of such could lead to the erroneous diagnosis of Birt-Hoggs Dubé syndrome.     

Socioeconomic gradients in health status over 29 years of follow-up after midlife: the Alameda county study

Socioeconomic status is well known to be associated with inverse gradients in a wide range of health outcomes. Very little is known about the precise shape of these relationships and how they evolve through the life-course, although recent work has suggested steep non-linearities for mortality in samples of the entire population that include the very poor. We investigate the shape of gradients, against baseline family income, in gender-specific prevalence rates for seven self-reported health outcomes commonly used on surveys, in a cohort of 1190 men and 1302 women representative of Alameda County, California, aged 40-59 in 1965. Over 29 years of follow-up, four different prevalence-income gradients among surviving subjects are examined as this cohort has aged, in 1965, 1974, 1983 and 1994. Virtually all the gradients are inverse, although there is no simple pattern of shape, or evolution of shape over time, across health outcomes. However, there is a consistent trend for male gradients to be distinctly more non-linear than female gradients, such that the poorest men show disproportionately higher rates of ill health, based on generalized linear piecewise regression models, comparing the low versus high-income slopes of the gradients. However, sub-analyses of only those long-lived cohort members, who survived through all follow-ups, largely abolished the non-linearities in the male prevalence curves (except for "self-assessed health status" and "depression"), making them much more like female curves. This suggests that for all of these common forms of morbidity, the excess prevalence among very low income males was associated with elevated mortality. Confirmation of this observation must await richer data on other aspects of socioeconomic status in comparable cohorts, analyzed with similar methods.     

Cytomegalovirus infection in infancy: virological and immunological studies

Immunological and virological studies on 18 infants with cytomegalovirus (CMV) infection were performed. Eleven of these infants were studied on multiple occasions over a period of 1 year. The patients were divided into three clinical groups based on the probable time of infection and the resulting variation in clinical presentation. General parameters of cell-mediated immunity as determined by E-rosette formation and lymphocyte proliferative responses to mitogens and antigens were found to be normal. Quantitation of CMV excretion in urine, CMV-specific immunofluorescent (IF) and complement-fixing (CF) antibody titres and CMV-specific cell-mediated immune responses were done on all patients at approximately monthly intervals. Throughout the study period all patients continued to excrete CMV despite the presence of high antibody titres to the virus. CMV-specific lymphocyte proliferative responses were absent or diminished in 15 of the 18 patients. The immunological and virological status of all patients was similar regardless of the clinical manifestation of infection.     

Does Mycobacterium avium subspecies paratuberculosis cause Crohn's disease?

Reassessing this persistent theory in light of advances in molecular microbial detection and genetic pathogenesis of disease.     

Population pharmacokinetics of valganciclovir prophylaxis in paediatric and adult solid organ transplant recipients

Aim

Our aims were to quantify ganciclovir pharmacokinetics in paediatric and adult kidney, liver and lung transplant patients taking a range of valganciclovir doses to prevent herpes virus infections, including a 450 mg regimen, and to identify sources of pharmacokinetic variability.

Method

Plasma samples were collected at 2, 4, 8 and 12 weeks post-transplant and at 4, 6, 8 and 12 months post-transplant in subjects prescribed longer courses. Ganciclovir was measured by liquid chromatography/ultraviolet detection. Non-linear mixed effects modelling was used to analyze the concentration–time data and evaluate demographic and transplant-related covariates.

Results

A two compartment model with first order absorption best described the data. Given the range of body sizes, clearance and volume of distribution terms were scaled using standard weight-based allometric exponents. Creatinine clearance was included on apparent oral clearance. Final estimates in a standard 70 kg individual for apparent oral clearance, central volume of distribution, intercompartmental clearance and peripheral volume of distribution were 14.5 l h⁻¹, 87.5 l, 4.80 l h⁻¹ and 42.6 l, respectively. The median terminal half-life for kidney, liver and lung transplant recipients was 9.4, 9.5 and 8.2 h, respectively. Median exposure (i.e. AUC(0,∞) in subjects taking valganciclovir 900 mg or 450 mg once daily was 57.4 and 34.3 μg ml⁻¹ h, respectively.

Conclusion

Allometric scaling allowed simultaneous analysis of data from children and adults. Ganciclovir pharmacokinetics were similar among kidney, liver and lung transplant recipients. Ganciclovir exposure after valganciclovir 450 mg once daily may be suboptimal in some individuals and requires evaluation along with virologic outcomes data.     

HIV Knowledge Among Canadian-Born and Sub-Saharan African-Born Patients Living with HIV

Research has revealed differences on scales measuring HIV knowledge between individuals from various ethnic backgrounds and cultures. Few studies have examined this knowledge with immigrant populations and persons living with HIV. This study examined HIV knowledge among persons living with HIV who were either born in Canada or in sub-Saharan Africa and, for comparison, in a sample of college students. All participants were residing in Canada. Participants completed questionnaires measuring demographic variables, sexual health behaviour, and HIV status, treatment, and knowledge. Canadian-born patients living with HIV were more likely to be older and male than the other groups. On average, patients living with HIV were diagnosed 6.4 years ago, and 80% reported having current or previous experience taking HIV medications. After adjusting for age and gender, significant differences were found between the groups on the Brief HIV Knowledge Questionnaire. Canadian-born persons living with HIV (n = 110) scored higher than sub-Saharan African-born patients (n = 23) and college students (n = 81); mean percentage correct was 86, 70, and 62%, respectively (P < .01). These results suggested that ongoing HIV education is needed for all groups, and that additional tailored and targeted educational interventions are needed to address important gaps in knowledge among persons living with HIV patients originating from Africa and among college students.     

Chilaiditi Syndrome Precipitated by Colonoscopy: A Case Report and Review of the Literature

Chilaiditi syndrome is a rare condition defined by the presence of gastrointestinal symptoms associated with the radiological finding of segmental interposition of the bowel between the liver and the diaphragm. While it is infrequently indentified as a source of abdominal pain, Chilaiditi syndrome carries clinical significance as it can lead to a number of serious complications including intestinal obstruction, perforation, and ischemia. A 58-year-old woman presented with Chilaiditi syndrome immediately following colonoscopic evaluation. Conservative measures failed to alleviate the patient''s symptoms, and the patient ultimately elected to have operative management. Pexy of the cecum and ascending colon led to full resolution of her symptoms. To our knowledge, this is the first documented case of Chilaiditi syndrome iatrogenically induced by colonoscopy. Identification of this syndrome as a complication of colonoscopy and a source of post-procedural pain bears significance for providers involved in the peri-operative care of patients with factors predisposing them to the development of this condition.