Spatial-temporal clusters of host-seeking Aedes albopictus, Aedes japonicus, and Aedes triseriatus collections in a La Crosse virus endemic county (Knox County, Tennessee, USA).

A bite from a La Crosse virus (LACV) infected Aedes mosquito can cause La Crosse encephalitis (LACE), which is a neuro-invasive disease that disproportionately affects children under the age of 16 in Southern Appalachia. The three vectors for LACV are Aedes albopictus (Skuse), Ae. japonicus (Theobald), and Ae. triseriatus (Say). Localized maps of the geographic distribution of vectors are practical tools for mosquito management personnel to target areas with high mosquito abundance. This study hypothesized that LACV vectors have unique species-specific spatial and temporal clusters. To test this, 44 sites were identified in Knox County, Tennessee for their land use/type. At each site, host-seeking mosquitoes were collected approximately every other week from May-October 2018. Spatial clusters of host-seeking mosquito collections for each of the three mosquito species were investigated using Kulldorff's spatial scan statistic, specifying a retrospective space-time Bernoulli model. Most vector clusters were identified in south-central Knox County while the seasonality of clusters varied by mosquito species. Clusters of Ae. albopictus were observed throughout the entire study period while clusters of Ae. japonicus and Ae. triseriatus only occurred May-June. The findings indicate that the relative abundance of LACV vectors were more abundant in south-central Knox County compared to the rest of the county. Of interest, these clusters spatially overlapped with previous LACE diagnosed cases. These findings are useful in guiding decisions on targeted mosquito control in Knox County and may be applied to other counties within Southern Appalachia.

Aedes albopictus oviposits with other Aedes species in artificial oviposition cups: a case study in Knox County, Tennessee, U.S.A.

Interspecific associations between two mosquito species can lead to effects such as competition, species displacement, and species stability. To better understand Aedes albopictus (Skuse) and other Aedes species, we monitored eggs in artificial oviposition cups (ovitraps) within Knox County, TN, U.S.A., during the 2016 and 2017 mosquito seasons. In 2016, one black and one white ovitrap were placed at 18 sites for 21 weeks, while in 2017 black and white ovitraps baited with grass-infused or deionized water were placed at 11 sites for nine weeks. Eggs were identified to species and resulting counts were used to determine the degree of interspecific association using Cole's coefficients (C7 ) and the degree of heterogeneity across space and time using generalized linear mixed models (GLMM). Here, Aedes mosquitoes are generally ovipositing in black cups with grass-infused water, and Ae. albopictus eggs co-occurred with other Aedes species more often than would be expected. Finding a positive significant interspecific association between Ae. albopictus and other Aedes eggs suggests that methods used to control Ae. albopictus may also control other Aedes mosquitoes. Finding that Ae. albopictus co-occurs with other Aedes mosquitoes warrants additional research to evaluate outcomes associated with co-occurrence within the study area.

Measuring heart patients' willingness to pay for changes in angina symptoms.

Willingness-to-pay (WTP) measures of the effects of changes in health on a person's welfare are more comprehensive than traditional cost-of-illness (COI) measures, but they are sometimes difficult to obtain. The authors investigated two approaches for measuring heart patients' WTP for changes in their angina symptoms. First, actual expenditures and perceived angina episodes avoided were used to infer an averting-behavior measurement of WTP. Second, a contingent-valuation approach was used to ask direct WTP questions regarding a hypothetical medical treatment that could be purchased to avoid additional angina episodes. The results indicated that although negligible COI changes were expected with small changes in angina frequency, the subjects had significant WTP to avoid increases in angina. The average WTP to avoid additional angina episodes revealed by the averting-behavior questions was comparable to the directly-elicited WTP, providing a test of the validity of the contingent-valuation approach.

An increased incidence of total anomalous pulmonary venous drainage among aboriginal Canadians.

OBJECTIVE: To determine whether Aboriginal Canadians from Manitoba and Ontario have an increased incidence of isolated total anomalous pulmonary venous drainage (TAPVD) and to compare results obtained from two different data sources and time periods. DESIGN: A nonconcurrent cohort study was undertaken. Incidence rates and relative risk from 'traditional' data sources (cases from medical records data; births from Census, Vital Statistics and Native Registry data for Manitoba and Ontario) from 1972-84 were derived and compared with those from computerized hospital abstract data from Manitoba for 1987-91. RESULTS: Using traditional data sources an incidence of 0.282/1000 live births was noted in Aboriginals versus 0.062 in non-Aboriginals for a relative risk of 4.6 (95% CI = 2.7-7.7). For Manitoba only the relative risk was 5.8 (95% CI = 2.6-12.8). Using computerized administrative data from Manitoba the relative risk was 5.8 (95% CI = 1.3-25.8). CONCLUSION: There is an increased incidence of isolated TAPVD in Aboriginal peoples from Manitoba and Ontario. Further epidemiological investigation is necessary to determine the nature of this association.

Results from an international survey of Kawasaki disease in 1979-82.

Kawasaki disease is a febrile illness of unknown etiology affecting mainly children younger than five years, 20% of whom develop coronary artery aneurysms. The disease was first reported in Japan, but case reports have come from several countries; epidemics apparently occur every two to three years. A committee of the International Society and Federation of Cardiology (ISFC) collaborated on an international, retrospective survey in mid-1983 through 1984, asking about Kawasaki disease cases seen in 1979-82 and their outcomes. Responses were received from 53 countries; reports from 20 countries indicated that no cases were seen in the years surveyed. Kawasaki disease did not always follow the Japanese pattern. An indication of 'epidemic' increases was found in some years in some countries. Recognition of Kawasaki disease varies considerably, but further educational efforts are likely to uncover additional cases, and intensive epidemiological efforts would be possible in a number of countries.

Determination of left ventricular volumes by Simpson's rule in infants and children with congenital heart disease.

Regression equations were developed from left ventricular casts of known volumes to calculate left ventricular volumes from biplane cineangiography obtained in non-standard views. Volumes were calculated by Simpson's rule from casts of postmortem specimens from patients with congenital heart disease. The casts were divided into two groups: those that came from patients with abnormal right ventricular haemodynamic function (group 1, n = 11) and those that came from patients in which it was normal (group 2, n = 9). Biplane cinegrams were taken in conventional (anteroposterior/lateral, right anterior oblique/left anterior oblique) and non-conventional (long axis oblique, hepatoclavicular, and sitting up) projections. The true volume of each cast was determined from its weight and specific gravity. Correlations between measured and true volumes (r = 0.96 to 0.99) were excellent in all projections, although each projection overestimated the true volumes (slope = 0.72 to 0.94). The regression equations obtained from conventional views were significantly different from those from the non-conventional views; however, the regression slopes in group 1 were not different from those in group 2 in any view. Regression equations obtained by Simpson's rule do not seem to be affected by the haemodynamic state of the right ventricle. Different regression equations are required to measure left ventricular volumes from non-conventional angiograms.

Persistence of atrioventricular valve regurgitation and electrocardiographic abnormalities following transient myocardial ischemia of the newborn.

To determine the sequelae of transient myocardial ischemia (TMI) in term infants, we reviewed clinical and investigative data in 59 infants (37 male, 22 female) with structurally normal hearts admitted over the 2-year period of 1983-1985. Twenty-three were diagnosed prior to admission as cases of birth asphyxia (5-min Apgar score less than 6), and 36 had signs of persistent fetal circulation with electrocardiographic (ECG) changes of ischemia greater than 24 h after birth. Murmurs of atrioventricular valve regurgitation (AVVR), detected in 28 patients, were confirmed in 23 of the 24 patients investigated. The murmurs resolved over a 2-day to 6-month period (median 6 days). In three patients, AVVR, left ventricular dyskinesia, and ECG anomalies persisted for 2 months (until death), 4 months, and 48 months. Initial ECGs were abnormal in 57 patients, and (of those reviewed) 60% returned to normal over a 6-day to 7-month period (median 2 months). Residual ECG anomalies included second-degree AV block and persistent ST-T wave changes. Ten patients died from noncardiac causes. Neither the presence nor resolution of AVVR correlated significantly with the severity of birth asphyxia using the Apgar score, nor with the severity of the ischemic changes on the ECG. Although the cardiovascular sequelae of myocardial ischemia are usually transient, the data should prompt the need for careful review after the initial admission.

Catheter occlusion of the persistently patent ductus arteriosus.

Catheter occlusion of a persistently patent ductus arteriosus was attempted in 40 patients (11 men and 29 women, mean age 7.2 +/- 8.3 years, range 244 days to 40 years), using a transvenously placed Rashkind umbrella occluder (USCI). Thirty-one 12-mm and six 17-mm diameter devices were successfully placed in the ductus (internal diameter average 3.9 mm, range 2 to 9 mm). One procedure was abandoned when fluoroscopy failed to visualize the device. There were 2 immediate embolizations subjected to surgical recovery. A residual shunt was present on the immediate postocclusion ventriculogram in 12 of 37 procedures (32%). Twenty-eight patients (75%) have had at least a follow-up at 3 months with Doppler study and 6 (21%) continued to have shunting into the pulmonary artery. Three of 4 patients have undergone successful placement of a second device and 1 patient's shunting spontaneously resolved at 1 year postimplant, leaving only 2 patients (7%) with persistent shunts. There has been 1 episode of probable prosthetic endarteritis and 1 patient has developed mild narrowing of the left pulmonary artery related to device placement. Catheter occlusion of the patent ductus arteriosus using the Rashkind umbrella appears to be a safe and effective method of non-surgical management.

Natural history and prognostic risk factors in endocardial fibroelastosis.

A retrospective study was made of 52 patients (16 men, 36 women) with endocardial fibroelastosis diagnosed by strict clinical criteria and confirmed histologically in 18 (35%). Clinical and hemodynamic manifestations at presentation were reviewed from the clinical record. The follow-up period averaged 47 months (range 1 day to 228 months). Actuarial survival rates were 93% at 6 months, 83% at 1 year and 77% at 4 years. Clinical and hemodynamic manifestation included onset at less than 1 year of age (89%), respiratory distress (71%), cardiomegaly on chest roentgenogram (99%), left ventricular hypertrophy with ST-T-wave changes on the electrocardiogram (97%) and reduced contractility with dilatation of the left ventricle (100%). Prognostic risk factors were evaluated comparing 13 patients who died (group 1) with 16 patients who survived greater than 4 years (group 2). Only cardiac index (2.8 +/- 0.8 vs 3.5 +/- 0.5 liter/min/m2) and ejection fraction (18 +/- 12 vs 33 +/- 21%) measured at catheterization were significantly reduced in group 1 compared with group 2 (p less than 0.005 and p less than 0.01, respectively). Careful observation and appropriate management are recommended in all patients, although low ejection fraction and cardiac output at presentation are predictive of poor outcome and support other therapeutic alternatives.

Cardiac manifestations in disorders of fat and carnitine metabolism in infancy.

The prognosis of patients with cardiomyopathy associated with hypocarnitinemia is uncertain. Cardiac hemodynamics, histologic findings and response to oral L-carnitine therapy were retrospectively evaluated in 11 children with cardiomyopathy associated with abnormal carnitine metabolism. Three had systemic carnitine deficiency, two familial hypocarnitinemia with neutropenia, three transient neonatal hypocarnitinemia and three a carnitine insufficiency syndrome. Six had a hypertrophic and five a dilated cardiomyopathy. Hypotonia was present in seven (64%). The cardiothoracic ratio was greater than 0.60 in eight (73%). The most frequent abnormality on the electrocardiogram was ST-T wave inversion in the left precordial leads with various degrees of left ventricular hypertrophy. Echocardiographically, two patients with hypertrophic cardiomyopathy had decreased left ventricular function and two patients with dilated cardiomyopathy had increased thickness of the left ventricular wall. Histologic evaluation (two autopsies and one endomyocardial biopsy) revealed striking lipid accumulation within hypertrophied myocytes. Six of eight patients on carnitine replacement therapy had improvement echocardiographically during a 3 month to 2 year follow-up period. In summary, both hypertrophic and dilated cardiomyopathy can result from abnormal carnitine metabolism. The determination of plasma carnitine concentrations and fatty acid metabolism by-products should be performed in all patients with either form of cardiomyopathy of unknown etiology because carnitine supplementation may lead to improvement.

Angiographic features associated with percutaneous balloon valvotomy for pulmonary valve stenosis.

Changes in the mobility of the pulmonary valve were determined by a retrospective review of right ventricular cineangiograms from 25 balloon pulmonary valvotomy (BV) procedures in 23 infants and children. The angiographic changes were compared with the post-BV catheter and Doppler pressure gradients across the right ventricular outflow tract. Angiographic features felt to indicate valve tearing were present following 17 of 25 procedures and included increased excursion or straightening of leaflets, localized change in leaflet motion (flail leaflet), and the presence of an additional contrast jet through the valve. There was no statistically significant relationship between any of the angiographic parameters and the pressure data. Most patients with marked increase in angiographic valve mobility had low residual right ventricular to pulmonary artery gradients. However, the absence of angiographic change was not always associated with a high residual gradient.

Ventricular tachycardia related to transcutaneous pacing.

A 3-year-old child with Haemophilus influenzae endocarditis and aortic route abscesses presented with sudden cardiovascular collapse. During resuscitation, the child was noted to be in complete heart block. Transcutaneous pacing was instituted three times, and ventricular dysrhythmias were associated with each pacing attempt. When pacing was discontinued, the patient spontaneously reverted to complete heart block without ventricular ectopy. An emergency thoracotomy revealed rupture of the aortic route, and the patient died during surgery. Transcutaneous pacing may precipitate serious dysrhythmias; appropriate precautions are recommended.

Thrombolytic therapy for femoral artery thrombosis after pediatric cardiac catheterization.

Femoral artery thrombosis remains a well-known complication after cardiac catheterization. A study was undertaken to assess the efficacy of thrombolytic therapy for this complication. A total of 526 consecutive infants and children were prospectively evaluated after cardiac catheterization, and the medical charts of 42 patients who required femoral artery thrombectomy between 1975 and 1985 were reviewed. In the prospective study, patients were given a bolus injection of heparin, 150 U/kg, at the time the artery was entered. Patients with persistently absent or diminished pulse 2 hours after catheterization received a second bolus injection of 50 U/kg followed by an infusion of 20 U/kg/hr heparin for a maximum of 48 hours. If the affected leg pulse was absent or reduced and the systolic Doppler blood pressure was less than two thirds that of the unaffected leg, thrombolytic therapy was begun. In the 42 patients with surgical thrombectomy, there were no serious complications of surgery. Forty-five of the 526 patients (8.6%) had a decreased or absent pulse after catheterization. Of these 45 patients, 32 (71.1%) improved with systemic heparinization only. Thirteen patients (28.9%) had a persistently absent pedal pulse suggesting femoral artery thrombosis, despite continuous heparinization. Eleven patients were successfully treated with thrombolytic therapy and two required surgical thrombectomy. Intraarterial balloon dilatation procedures were performed in 8 of these 13 patients. Prothrombin time was prolonged (11.5 +/- 1.06 to 52.3 +/- 40.4 seconds; p less than 0.025) and fibrinogen levels were significantly reduced (2.25 +/- 0.79 to 1.52 +/- 0.52 gm/dl; p less than 0.01) during therapy. There were no serious complications, although four patients bled from the groin entry site.(ABSTRACT TRUNCATED AT 250 WORDS)

Correlation of left ventricular angiographic casts and biplane left ventricular volumetry in infants and children.

To calculate left ventricular (LV) volumes from biplane cineangiography obtained in nonstandard views, regression equations were developed from LV casts of known volume. Volumes were calculated by the area-length method from casts ranging from 1.4 to 48.9 ml obtained from 30 postmortem cases with heart disease. The casts were divided into 2 groups: group I (n = 17) with abnormal and group II (n = 13) with normal right ventricular hemodynamics. Biplane cinegrams were taken in the anterolateral, anterior and long axial oblique, hepatoclavicular and sitting-up projections. The true volume of each cast was determined from its weight and specific gravity. In both groups, excellent correlations were obtained between measured and true volumes (r = 0.92 to 0.99) in all projections, although each projection overestimated the true volume (slope value less than 1). The regression equations obtained from group I were significantly different from those in group II in all views (p less than 0.025 to 0.05), with smaller mean differences and standard errors of the estimate. These data support the concept that right ventricular hemodynamics influence ventricular septal position and, therefore, LV geometry and measured volumes. Appropriate regression equations are required to allow volume calculation from multiple projections.

Correlation of right ventricular volume using axial angulated ventriculography to known right ventricular cast volumes in infants and children with congenital heart disease.

To calculate right ventricular (RV) volumes from biplane cineangiography obtained in nonstandard views, regression equations were developed from RV casts of known volume. Volumes were calculated using Simpson's rule from casts ranging from 2 to 42 ml from 25 postmortem specimens with various congenital heart diseases. The casts were divided into 2 groups: group 1 (n = 15) with abnormal or group 2 (n = 10) with normal RV hemodynamic measurements. Biplane cinegrams were taken in the anterolateral, anterior and long axis oblique, hepatoclavicular and sitting up projections. The true volume of each cast was determined from its weight and specific gravity. Excellent correlations were obtained between measured and true volumes (r = 0.92 to 0.96) in all projections, although each projection overestimated the true volume (slope value less than 1). The regression equations obtained from group 1 were not statistically different from those in group 2 in any view. Although the application of different regression equations is required in measuring RV volumes by multiple angulated angiography, these regression equations appear not to be affected by the hemodynamic state of the ventricle. These results are important in assessing RV volume in pediatric patients with congenital heart disease using axial angulated ventriculography.

Noninvasive transcutaneous cardiac pacing in children.

Noninvasive transcutaneous cardiac pacing is an emergency pacing modality with proven benefits for adult patients. During induction of anesthesia for heart surgery, we externally paced 22 children (aged 0.9-17.9 years and weighing 6.96 to 51 kg) using a commercially available device to pace approximately 10 beats per minute faster than the spontaneous heart rate. Three pacing electrode sizes were used (the standard adult size and two specially manufactured smaller sizes). A total of 56 pacing trials were conducted, 53 of which were successful in obtaining capture. A mean output of 63 +/- 14 mA (range, 42-98) at threshold using the large electrodes was comparable to published adult requirements. Lower current outputs were needed with the medium (53 +/- 12 mA; range, 36-92) and small electrodes (51 +/- 11 mA; range, 29-82). In any given patient, the large electrodes required more current (p less than 0.01) to obtain capture, but delivered less current density (p less than 0.01) and exhibited less impedance (p less than 0.01) than the smaller electrodes. The mean threshold energy requirement was 0.12 +/- 0.01 joules/beat regardless of pad size. Output, current density, impedance and energy requirements did not vary with age, weight or chest size. No complications of external pacing were noted. We conclude that noninvasive transcutaneous pacing can be used safely and effectively in children, and that chest size might necessitate the use of smaller electrodes in children weighing less than 15 kilograms.

Abnormal endothelial factor VIII associated with pulmonary hypertension and congenital heart defects.

In patients with pulmonary hypertension associated with congenital heart defects, ultrastructural abnormalities are observed in endothelial cells, which suggest heightened metabolic function. If endothelial production of the von Willebrand factor (vWF) is increased, this may be associated with abnormal interactions with platelets leading to worsening of the pulmonary hypertension. We therefore evaluated vWF in 30 patients with pulmonary hypertension (25 with congenital heart defects) and in 30 individuals with normal pulmonary arterial pressure (12 with congenital heart defects). We measured the antigenic (vWF: Ag) and biologic (VWF: rist) activity of vWF in plasma and assessed endothelial vWF: Ag directly by an immunoperoxidase stain applied to lung biopsy tissue. Because of considerable variance and small size, the group of five patients with pulmonary hypertension and without congenital heart defects were excluded from statistical analyses. Patients with pulmonary hypertension and congenital heart defects had significant higher vWF: Ag levels than individuals with normal pulmonary arterial pressure without congenital heart defects (p less than .05), whereas values in those with normal pressure and congenital heart defects were intermediate. In lung biopsy tissue available from 29 patients in this study and from 11 others we previously reported, immunostain of pulmonary arterial endothelium for vWF was intense (suggesting increased production) in 29 of 32 with pulmonary hypertension and congenital heart defects and in only one of eight with normal pulmonary arterial pressure and congenital heart defects (p less than .01). Only three patients with congenital heart defects and pulmonary hypertension and increased vWF: Ag, however, had increased vWF: rist. Compatible with this discrepancy was a loss of vWF high-molecular weight forms as determined by both crossed immunoelectrophoresis and multimeric analysis. Our results suggest that increased vWF in most patients with congenital heart defects and pulmonary hypertension is associated with increased production of a biologically deficient molecule lacking high-molecular weight forms.

Critical aortic stenosis. Survival and management.

The factors associated with survival in 40 neonates (age less than 28 days) with critical aortic stenosis undergoing either open (22 patients) or closed (18 patients) transventricular aortic valvotomy were reviewed. Significant adverse correlates with survival included evidence of poor perfusion preoperatively (low pH, greater than Grade 2/6 soft ejection systolic murmur) and marked congestive heart failure (hepatomegaly, cardiomegaly, elevated left atrial pressure). Congenital mitral stenosis (anulus less than 11 mm), a small aortic anulus (less than 6.5 mm), and failure to achieve an adequate aortic orifice (greater than 6 mm), at operation were identified as factors associated with increased mortality. Initial perioperative survival was better with closed aortic valvotomy. However, there was no significant difference in overall operative survival between closed (9/18, 50%) and open (8/22, 36%) aortic valvotomy (p = 0.26). The incidence of early reoperation (less than 1 year of age) was greater in perioperative survivors undergoing closed valvotomy (7/13, 54%) rather than open valvotomy (1/10, 10%) (p less than 0.05). In conclusion, long-term survival among patients with critical neonatal aortic valve stenosis remains disturbingly low (13/40, 32%) and has not significantly improved over the past 20 years.

The morphology of the right ventricular outflow tract after percutaneous pulmonary valvotomy: long term follow up.

Twenty nine patients (19 male, mean (SD) age 6.25 (0.5) years (range 0.16-15 years] with typical pulmonary valve stenosis were treated by balloon dilatation of the pulmonary valve. They were studied by echocardiography before the procedure, immediately after it, and at follow up (mean (SD) 10.2 (5.6) months, n = 18). The morphology of the pulmonary valve, the right ventricular-pulmonary artery gradient, and ratio of the systolic to diastolic endocardial dimensions (infundibular ratio) were examined. No patient had pulmonary regurgitation before the study. The valve gradient was significantly reduced (47%) from a mean (SD) of 72 (31) to 37 (23) mm Hg with no short term change in cardiac index after dilatation with a balloon with a mean (SD) diameter that was 118 (10.8)% of the valve annulus. The infundibular ratio was unchanged by the procedure (0.49 (0.11) (n = 21) before dilatation and 0.47 (0.14) (n = 16) after dilatation). In twenty seven patients the commissure of the pulmonary valve was seen to be torn after dilatation. Two patients with bicuspid valves had flail leaflets. Doppler examination at follow up showed mild pulmonary insufficiency in all 29 patients; the mean (SD) valve gradient (31 (+/- 21) mm Hg) at follow up was no different from the gradient found immediately after the procedure and infundibular ratio (0.58 (0.15) was not abnormal. These data indicate that commissural tears are the primary mechanism of valve disruption and demonstrate that the dynamic right ventricular outflow tract obstruction relaxes and gradient reduction persists at follow up.