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Biomedical subjects

S D Colan

Publications and source records attributed to S D Colan.

At least 19 recordsLinked to original sources
PubMed2003

Growth of the aorta in children with Williams syndrome: does surgery make a difference?

Supravalve aortic stenosis (SAS) and arch hypoplasia are features of Williams syndrome. The effect of aortoplasty on growth of the aorta is not established. We hypothesize that growth of the aorta remains deficient whether or not aortoplasty has been performed. Review of the Children's Hospital of Pittsburgh database revealed 18 patients with Williams syndrome and SAS. Fourteen had sufficient data for inclusion. Patients were divided into two groups based on whether or not they had undergone aortoplasty (groups 1 and 2, respectively). Echocardiographic velocity estimates of the aorta were made at two time points in all patients and one additional time point postoperatively for group 1. Measurements were converted to zeta scores and compared. Peak pulsed echo Doppler velocity (m/sec) in the ascending aorta was higher in patients who underwent aortoplasty. This decreased significantly after surgery. Preoperatively, there was no difference between the groups' annulus, ascending aorta, transverse aorta, and isthmus measurements. At a mean of 43 months postoperatively, there was no significant change in size of the ascending aorta, transverse aorta, and isthmus. Children with Williams syndrome have hypoplasia of the aortic arch that remains constant. Aortoplasty decreases the aortic gradient but has no effect on the size of the ascending aorta, transverse aorta, and aortic isthmus over the short-term.

Analysis of Variance↗
PubMed2001

Reliability of multicenter pediatric echocardiographic measurements of left ventricular structure and function: the prospective P(2)C(2) HIV study.

BACKGROUND: To assess the reliability of pediatric echocardiographic measurements, we compared local measurements with those made at a central facility. METHODS AND RESULTS: The comparison was based on the first echocardiographic recording obtained on 735 children of HIV-infected mothers at 10 clinical sites focusing on measurements of left ventricular (LV) dimension, wall thicknesses, and fractional shortening. The recordings were measured locally and then remeasured at a central facility. The highest agreement expressed as an intraclass correlation coefficient (ICC=0.97) was noted for LV dimension, with much lower agreement for posterior wall thickness (ICC=0.65), fractional shortening (ICC=0.64), and septal wall thickness (ICC=0.50). The mean dimension was 0.03 cm smaller in central measurements (95% prediction interval [PI], -0.32 to 0.25 cm) for which 95% PI reflects the magnitude of differences between local and central measurements. Mean posterior wall thickness was 0.02 cm larger in central measurements (95% PI, -0.18 to 0.22 cm). Mean fractional shortening was 1% smaller in central measurements. However, the 95% PI was -10% to 8%, indicating that a fractional shortening of 32% measured centrally could be anywhere between 22% and 40% when measured locally. Central measurements of mean septal thickness were approximately 0.1 cm thicker than local ones (95% PI, -0.18 to 0.34 cm). Centrally measured wall thickness was more closely related to mortality and possibly was more valid than local measurements. CONCLUSIONS: Although LV dimension was reliably measured, local measurements of LV wall thickness and fractional shortening differed from central measurements.

Cardiac Volume↗
PubMed2001

Left ventricular mechanics during and after acute rheumatic fever: contractile dysfunction is closely related to valve regurgitation.

OBJECTIVES: The purpose of this study was to characterize left ventricular (LV) mechanics during acute rheumatic fever (ARF) and to define factors influencing remodeling after the acute event. BACKGROUND: Acute rheumatic fever is associated with varying degrees of valvulitis and myocarditis, but the impact of these factors on LV mechanics is poorly defined. METHODS: Echocardiograms and clinical data were reviewed in 55 patients aged 11.2 +/- 2.6 years during ARF. Valve regurgitation was absent or mild in 33 (group I) and moderate or severe in 22 (group II). Forty-two children (75%) underwent a further examination after ARF. RESULTS: Group I patients demonstrated a mildly elevated LV size during ARF and had normal indexes at follow-up. Group II patients demonstrated a markedly elevated LV size (end-diastolic dimension z-score 3.6 +/- 1.8, p < 0.01 compared with the normal population) and decreased shortening fraction (z-score -0.8 +/- 1.4, p < 0.05). The stress-velocity index, a z-score describing the velocity of shortening-afterload relationship, was normal in group II patients with mitral regurgitation (-0.2 +/- 1.2, p = NS) but was depressed in those with aortic regurgitation or both (- 1.4 +/- 1.4, p < 0.01). At follow-up the stress-velocity index remained depressed (-1.2 +/- 1.0, p < 0.01) and had deteriorated in those treated nonsurgically compared with those treated surgically (interval change nonsurgical -0.7 +/- 1.2 vs. surgical 1.3 +/- 1.3, p = 0.005). CONCLUSIONS: The evolution of contractile dysfunction during and after ARF is dependent on the degree and type of valve regurgitation and may be influenced by surgical intervention. These findings suggest that mechanical factors are the most important contributors to myocardial damage during and after ARF.

Adolescent↗
PubMed2001

The risk of having additional obstructive lesions in neonatal coarctation of the aorta.

Infants with coarctation of the aorta may have obstructions at other sites within the left heart which are not always apparent on the initial echocardiogram. The magnitude of the risk of having the additional obstructions is not well described, with few reliable quantitative criterions for identifying patients at the highest risk. We determined the frequency of additional, late appearing, stenotic lesions within the left heart, and the predictive morphologic features on the initial cross-sectional echocardiogram. We identified all patients with coarctation of the aorta diagnosed by 3 months of age, excluding those with complex cardiac disease or definite additional stenotic lesions at presentation, leaving 101 patients for study. At follow-up, 31 stenotic lesions were diagnosed in 23 patients, 15 of whom had at least 1 intervention. Mitral stenosis was diagnosed in 11 patients, aortic stenosis in 10, subaortic stenosis in 8, and supravalvar aortic stenosis in 2. The probability for freedom from obstructive lesions was 81% at 1 year, 74% at 3 years, and 70% at 5 years. Echocardiographic predictors of mitral stenosis included smaller mitral valvar annuluses, presence of a mean transmitral gradient between 2.5 and 5.0 mmHg, and elongation of the area of intervalvar fibrous continuity. Predictors of aortic stenosis were smaller mitral valvar annuluses, an initial aortic valvar gradient between 15 and 20 mmHg, and obliteration of the commissure between the right and non-coronary leaflets of the aortic valve. Predictors of subaortic stenosis were smaller mitral valvar annuluses and elongation of the area of intervalvar fibrous continuity. Patients with Z-scores for the diameter of the mitral valve of less than -1 were at the highest risk for manifesting obstructive lesions at any level. Associated stenoses in the left heart are common in the setting of aortic coarctation. When Doppler data is equivocal, features of the cross-sectional echocardiogram can identify the sub-group of infants at increased risk.

Aortic Coarctation↗
PubMed2001

Dilation of the aortic root in children infected with human immunodeficiency virus type 1: The Prospective P2C2 HIV Multicenter Study.

BACKGROUND: Vascular lesions have become more evident in human immunodeficiency virus type 1 (HIV)-infected patients as the result of earlier diagnosis, improved treatment, and longer survival. Aortic root dilation in HIV-infected children has not previously been described. This study was undertaken to determine the prevalence of aortic root dilation in HIV-infected children and to evaluate some of the potential pathogenic mechanisms. METHODS: Aortic root measurements were incorporated into the routine echocardiographic surveillance of 280 children of HIV-infected women: an older cohort of 86 HIV-infected children and a neonatal cohort of 50 HIV-infected and 144 HIV-uninfected children. RESULTS: By repeated-measures analyses, mean aortic root measurements were significantly increased in HIV-infected children versus HIV-uninfected children (P values of < or =.04 and < or =.005 at 2 and 5 years of age, respectively, for aortic annulus diameter, sinuses of Valsalva, and sinotubular junction). Heart rate, systolic blood pressure, stroke volume, hemoglobin, and hematocrit were not significantly associated with aortic root size. Left ventricular dilation, increased serum HIV RNA levels, and lower CD4 cell count measurements were associated with aortic root dilation at baseline. CONCLUSIONS: Mild and nonprogressive aortic root dilation was seen in children with vertically transmitted HIV infection from 2 to 9 years of age. Aortic root size was not significantly associated with markers for stress-modulated growth; however, aortic root dilation was associated with left ventricular dilation, increased viral load, and lower CD4 cell count in HIV-infected children. As prolonged survival of HIV-infected patients becomes more prevalent, some patients may require long-term follow-up of aortic root size.

Aorta↗
PubMed2001

A pituitary tumor in a patient with thyroid hormone resistance: a diagnostic dilemma.

Resistance to thyroid hormone (RTH) is due to mutations in the beta-isoform of the thyroid hormone receptor (TR-beta). RTH patients display inappropriate secretion of thyrotropin-releasing hormone (TRH) from the hypothalamus and thyrotropin (TSH) from the anterior pituitary, despite elevated levels of thyroid hormone thyroxine (T4) and triiodothyronine (T3). Thyrotropin-secreting tumors are presumed to represent clonal expansion of abnormal cells. Because the diagnosis of TSH-secreting tumors tends to be delayed and curative surgical resection remains under 50%, early diagnosis is paramount. Current diagnostic strategies suggest that RTH patients are distinguishable from patients with TSH-secreting pituitary tumors by the use of standard laboratory tests and imaging. Here, we present a woman in whom the standard evaluation for inappropriate TSH secretion was insufficient to distinguish these entities. The patient had a low-normal TRH stimulation test and an unmeasurable alpha-glycoprotein subunit level; however, a pituitary magnetic resonance imaging (MRI) revealed an adenoma. More testing using a T3 suppression test supported a RTH diagnosis and a R438H mutation was found in the TR-beta gene. To our knowledge, this represents the first report of an apparently incidental pituitary adenoma in the setting of documented resistance to thyroid hormone. As such, it raises the question of whether RTH predisposes to pituitary hyperplasia and adenoma development.

Adenoma↗
PubMed2000

Cardiac dysfunction and mortality in HIV-infected children: The Prospective P2C2 HIV Multicenter Study. Pediatric Pulmonary and Cardiac Complications of Vertically Transmitted HIV Infection (P2C2 HIV) Study Group.

BACKGROUND: Left ventricular (LV) dysfunction is common in children infected with the human immunodeficiency virus (HIV), but its clinical importance is unclear. Our objective was to determine whether abnormalities of LV structure and function independently predict all-cause mortality in HIV-infected children. METHODS AND RESULTS: Baseline echocardiograms were obtained on 193 children with vertically transmitted HIV infection (median age, 2.1 years). Children were followed up for a median of 5 years. Cox regression was used to identify measures of LV structure and function predictive of mortality after adjustment for other important demographic and baseline clinical risk factors. The time course of cardiac variables before mortality was also examined. The 5-year cumulative survival was 64%. Mortality was higher in children who, at baseline, had depressed LV fractional shortening (FS) or contractility; increased LV dimension, thickness, mass, or wall stress; or increased heart rate or blood pressure (P0.02 for each). Decreased LV FS (P<0.001) and increased wall thickness (P=0.004) were also predictive of increased mortality after adjustment for CD4 count (P<0.001), clinical center (P<0.001), and encephalopathy (P<0.001). FS showed abnormalities for up to 3 years before death, whereas wall thickness identified a population at risk only 18 to 24 months before death. CONCLUSIONS: Depressed LV FS and increased wall thickness are risk factors for mortality in HIV-infected children independent of depressed CD4 cell count and neurological disease. FS may be useful as a long-term predictor and wall thickness as a short-term predictor of mortality.

Cardiovascular Diseases↗
PubMed2000

Absence of cardiac toxicity of zidovudine in infants. Pediatric Pulmonary and Cardiac Complications of Vertically Transmitted HIV Infection Study Group.

BACKGROUND: Perinatal exposure to zidovudine may cause cardiac abnormalities in infants. We prospectively studied left ventricular structure and function in infants born to mothers infected with the human immunodeficiency virus (HIV) in order to determine whether there was evidence of zidovudine cardiac toxicity after perinatal exposure. METHODS: We followed a group of infants born to HIV-infected women from birth to five years of age with echocardiographic studies every four to six months. Serial echocardiograms were obtained for 382 infants without HIV infection (36 with zidovudine exposure) and HIV-58 infected infants (12 with zidovudine exposure). Repeated-measures analysis was used to examine four measures of left ventricular structure and function during the first 14 months of life in relation to zidovudine exposure. RESULTS: Zidovudine exposure was not associated with significant abnormalities in mean left ventricular fractional shortening, end-diastolic dimension, contractility, or mass in either non-HIV-infected or HIV-infected infants. Among infants without HIV infection, the mean fractional shortening at 10 to 14 months was 38.1 percent for those never exposed to zidovudine and 39.0 percent for those exposed to zidovudine (mean difference, -0.9 percent; 95 percent confidence interval, -3.1 percent to 1.3 percent; P=0.43). Among HIV-infected infants, the mean fractional shortening at 10 to 14 months was similar in those never exposed to zidovudine (35.4 percent) and those exposed to the drug (35.3 percent) (mean difference, 0.1 percent; 95 percent confidence interval, -3.7 percent to 3.9 percent; P=0.95). Zidovudine exposure was not significantly related to depressed fractional shortening (shortening of 25 percent or loss) during the first 14 months of life. No child over the age of 10 months had depressed fractional shortening. CONCLUSIONS: Zidovudine was not associated with acute or chronic abnormalities in left ventricular structure or function in infants exposed to the drug in the perinatal period.

Anti-HIV Agents↗
PubMed2000

Non-invasive assessment of rejection in pediatric transplant patients: serologic and echocardiographic prediction of biopsy-proven myocardial rejection.

BACKGROUND: Cardiac allograft rejection is a multifocal immune process that is currently assessed using biopsy-guided histologic classification systems (International Society for Heart and Lung Transplantation). Cardiac troponin T and I are established serologic markers of global myocyte damage. The use of load-independent measures of contractility have also been shown to accurately assess the presence of ventricular dysfunction. Little is known about their utility in accurately predicting rejection in the pediatric age group. We undertook the present study to compare rejection grade with echocardiographic and serologic estimates of transplant rejection-related myocardial damage. METHODS: We compared histologic rejection grades (0 to 4) with patient characteristics, echocardiographic measurements, catheterization measurements, and biochemical markers for 86 evaluations in 37 transplant recipients at Children's Hospital. RESULTS: In univariate analyses, biopsy scores correlated (p < 0.05) inversely with left ventricular systolic function (shortening fraction) and contractility (stress velocity index, SVI), and directly with mitral E-wave amplitude. In multivariate analyses, lower contractility and higher mitral E-wave amplitude remained significantly (p < or = 0.01) associated with rejection (SVI, p = 0.002, odds ratio = 0.393; E wave, p = 0.0002, odds ratio = 228). Most rejection episodes were associated with elevation of biochemical markers of myocardial injury. Although troponin I was weakly associated with differences between rejection grades (p = 0.034), troponin T, creatine kinase-MB fraction, and C-reactive protein did not differ with biopsy-rejection scores. Serum markers had a poor predictive capacity for biopsy-detected rejection. Troponin T and I did correlate with increased left ventricular wall thickness and mass. CONCLUSION: Progressively depressed left ventricular contractility and diastolic function are found with worsening pediatric heart transplant rejection-biopsy score; however, sensitive and specific serum markers do not correspond to the degree of active myocardial injury. The use of echocardiographic measures of contractility is associated with a specificity of 91.8% but low sensitivity of 66.7%. Overall we found poor concordance between serum markers and grade of rejection. It is unclear whether myocardial injury as assessed by serum markers, echocardiography, or histologic scoring is more important for assessment of acute rejection or long-term outcome, but it does not appear that serum and tissue markers of rejection can be used interchangeably.

Adolescent↗
PubMed2000

Abnormal myocardial mechanics in Kawasaki disease: rapid response to gamma-globulin.

BACKGROUND: The time course and rate of recovery of myocardial dysfunction in association with Kawasaki disease in response to intravenous gamma-globulin is unknown and may provide mechanistic clues. METHODS AND RESULTS: The acute changes in myocardial contractility in 25 patients with Kawasaki disease were evaluated by noninvasive stress-shortening and stress-velocity analysis. Echocardiograms were performed before and then daily for 4 days during which the patients received gamma-globulin 1.6 to 2 g/kg. Before treatment, contractility was abnormally low (<2 SD) in 14 patients (56%). Contractility increased significantly (2 SD increase) in 17 (68%), including 13 of 14 with depressed contractility and 4 whose initial contractility fell within normal limits. Of the 14 patients with depressed contractility, 8 (57%) normalized within 24 hours and a further 5 (35.7%) normalized within 6 months. A clinical response to treatment (fall in C-reactive protein by 50% and/or resolution of fever within 4 days) was seen in 22 patients (88%). Contractility increased in 17 of the 22 clinical responders and was normal before therapy in the other 5. The 3 patients who did not respond clinically also had no change in contractility with gamma-globulin therapy. Long-term (more than 12 months) follow-up was available in 19 patients. All patients had normal contractility at late follow-up. CONCLUSIONS: More than half the patients with Kawasaki disease have abnormal contractility at presentation. Myocardial response to gamma-globulin therapy is associated with rapid improvement in myocardial mechanics, with a high concordance between the clinical and myocardial response to therapy. The speed of recovery suggests that depressed contractility in patients with Kawasaki disease is caused by a rapidly reversible process such as circulating toxins or activated cytokines. Long-term outcome is good even in those patients with slow recovery of myocardial function.

Child, Preschool↗
PubMed2000

Design and implementation of the North American Pediatric Cardiomyopathy Registry.

The Pediatric Cardiomyopathy Registry (PCMR) was established to describe the epidemiologic features and clinical course of selected cardiomyopathies in patients aged 18 years or younger and to promote the development of etiology-specific treatments. Sixty-one private and institutional pediatric cardiomyopathy practices in the United States and Canada were recruited to participate in the PCMR. The registry consists of a prospective, population-based cohort of patients in 2 regions (New England and the Central Southwestern United States) and a retrospective cohort of patients diagnosed between 1991 and 1996. Annual follow-up data are collected on all patients. As of June 1999, the PCMR consisted of 337 prospectively identified and 990 retrospectively identified patients. The PCMR has demonstrated the feasibility of establishing a large database of sociodemographic and clinical information on children with pediatric cardiomyopathy. Through this cooperative effort, the PCMR will obtain precise estimates of the incidence of pediatric cardiomyopathy and a better understanding of the natural history of this disease.

Adolescent↗
PubMed2000

Misrepresentation of left ventricular contractile function by endocardial indexes: clinical implications after coarctation repair.

BACKGROUND: Endocardial function indexes overestimate myocardial fiber shortening, a geometric effect proportional to wall thickness. We hypothesized that elevated endocardial indexes of left ventricular contractile function after repair of isolated coarctation of the aorta could be related to this effect. METHODS: Chamber dimensions and wall thickness were measured from 59 echocardiograms in 57 patients aged 1.2 to 32 years, 8.5 +/- 5.6 years after coarctation repair, and in 305 normal controls aged 1 to 35 years. Midwall and endocardial shortening indexes and end-systolic fiber stress were calculated. The stress-velocity index (SVI), a load-independent index of contractility, was derived from these variables. All values were expressed as z scores. RESULTS: After coarctation repair, the midwall-derived SVI was elevated, but significantly less so than the endocardial-derived SVI (0.6 +/- 1.6 vs 1.3 +/- 2.6; P =.01). The endocardial-derived SVI correlated with the end-systolic thickness/dimension ratio (P <.0001), but the midwall-derived SVI did not. There was no linear relation between the midwall-derived SVI and the residual blood pressure gradient. The mean midwall-derived SVI was higher compared with the normal population in those with a minor residual blood pressure gradient (</=15 mm Hg) and in those with more significant obstruction (>15 mm Hg), but this achieved statistical significance only in the latter group (0.5 +/- 1.6, P =.08; and 0.8 +/- 1.7, P =.03, respectively). CONCLUSIONS: Endocardial indexes of function and contractility overestimate fiber shortening after coarctation repair. Nevertheless, midwall shortening indexes demonstrate enhanced contractility, particularly in those with residual coarctation.

Adolescent↗
PubMed2000

Cardiac structure and function in fetuses of mothers infected with HIV: the prospective PCHIV multicenter study.

BACKGROUND: This study was designed to determine if vertically transmitted HIV infection and maternal infection with HIV are associated with altered cardiovascular structure and function in utero. METHODS: Fetal echocardiography was performed in 173 fetuses of 169 HIV-infected mothers (mean gestational age, 33.0 weeks; SD = 3.7 weeks) at 5 centers. Biparietal diameter, femur length, cardiovascular dimensions, and Doppler velocities through atrioventricular and semilunar valves and the umbilical artery were measured. Measurements were converted to z scores based on published normal data. RESULTS: Fetuses determined after birth to be HIV-infected had similar echocardiographic findings as fetuses later determined to be HIV-uninfected except for slightly smaller left ventricular diastolic dimensions (P =.01). The femur length (P =.03) was also smaller in the fetuses postnatally identified as HIV-infected. Differences in cardiovascular dimensions and Doppler velocities were identified between fetuses of HIV-infected women and previously published normal fetal data. The reason for the differences may be a result of maternal HIV infection, maternal risk factors, or selection bias in the external control data. CONCLUSIONS: Vertically transmitted HIV infection may be associated with reduced left ventricular size but not with altered cardiac function in utero. Fetuses of HIV-infected mothers may have abnormal cardiovascular structure and function and increased placental vascular resistance, regardless of whether the fetuses are subsequently found to be infected with HIV.

Adult↗
PubMed2000

Reconstruction of 3-dimensional right ventricular shape and volume from 3 orthogonal planes.

This study validates a reconstructive technique that describes 3-dimensional right ventricular (RV) shape and volume with the use of 3 standard echocardiographic planes. The volume of 24 cast models of lamb right ventricles (12 normal, 12 hypertensive) was determined by water displacement. Reconstruction of the cast shapes was calculated from 2 sets of digitized data: cast cross-sectional digitized tracings and echocardiographic cross-sectional tracings. Regional volume ratios from both data sets were assessed to quantitatively specify RV regional volume differences between normotensive and hypertensive right ventricles. This method described the 3-dimensional RV shape with no differences between reconstructed volumes and true volumes for either normotensive or hypertensive casts. Between hypertensive and normal groups, regional volume ratios yielded a difference in free wall ratios that was observed to be greater in the hypertensive cast group (P =.007).

Animals↗
PubMed2000

A new quantitative method for the diagnosis of right ventricular hypertensive disorders in 3 dimensions.

UNLABELLED: A new 3-dimensional (3D) method is described for the diagnosis of normal and hypertensive right ventricular (RV) conditions on the basis of similarity of RV structure to models of normal average shape or hypertensive average shape. Right ventricular quantification in multiple views (coronal, sagittal, and transverse) was obtained by measuring tangent angle differences (TADs) between RV tracings and average shapes at 128 points around the ventricular contour in each view. The TAD measurements of all views were then combined to quantify the closest 3D fit of the ventricle to a normal or hypertensive model. RESULTS: In 24 lamb casts measured in vitro, an accurate diagnosis was obtained in 11 of 12 normotensive casts (specificity 92%) and 11 of 12 hypertensive casts (sensitivity 92%). CONCLUSION: Accurate 3D diagnosis of in vitro normotensive and hypertensive RV conditions can be realized by measuring the TADs between the ventricle and average-shaped models.

Animals↗