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Colin J McMahon

Publications and source records attributed to Colin J McMahon.

At least 19 recordsLinked to original sources
PubMed2006

Left ventricular non-compaction cardiomyopathy in children: characterisation of clinical status using tissue Doppler-derived indices of left ventricular diastolic relaxation.

BACKGROUND: Left ventricular non-compaction (LVNC) may manifest an undulating phenotype ranging from dilated to hypertrophic appearance. It is unknown whether tissue Doppler (TD) velocities can predict adverse clinical outcomes including death and need for transplantation in children with LVNC. METHODS AND RESULTS: 56 children (median age 4.5 years, median follow-up 26 months) with LVNC evaluated at one hospital from January 1999 to May 2004 were compared with 56 age/sex-matched controls. Children with LVNC had significantly decreased early diastolic TD velocities (Ea) at the lateral mitral (11.0 vs 17.0 cm/s) and septal (8.9 vs 11.0 cm/s) annuli compared with normal controls (p<0.001 for each comparison). Using receiver operator characteristic curves, the lateral mitral Ea velocity proved the most sensitive and specific predictor for meeting the primary end point (PEP) at 1 year after diagnosis (area under the curve = 0.888, SE = 0.048, 95% CI 0.775 to 0.956). A lateral mitral Ea cut-off velocity of 7.8 cm/s had a sensitivity of 87% and a specificity of 79% for the PEP. Freedom from death or transplantation was 85% at 1 year and 77% at 2 years. CONCLUSIONS: TD velocities are significantly reduced in patients with LVNC compared with normal controls. Reduced lateral mitral Ea velocity helps predict children with LVNC who are at risk of adverse clinical outcomes including death and need for cardiac transplantation.

Adolescent↗
PubMed2006

Failure of cutting balloon angioplasty to prevent restenosis in childhood pulmonary venous stenosis.

We describe bilateral pulmonary vein stenosis in a 5-year-old boy. He initially presented with haemoptysis secondary to left upper lobe pulmonary vein atresia and left lower lobe stenosis and subsequently he underwent left-sided pneumonectomy. He underwent repeat cardiac catheterizations with repeated balloon angioplasty of the right-sided venous stenoses using a cutting balloon. Despite satisfactory initial results the pulmonary venous stenosis reoccurred as early as 2 months following balloon angioplasty. Although cutting balloon angioplasty has demonstrated effective immediate alleviation of pulmonary venous stenosis its utility in providing sustained improvement in pulmonary vein stenosis is limited.

Angioplasty, Balloon↗
PubMed2006

Successful surgical resection of intrapericardial extralobar pulmonary sequestration with congenital pulmonary adenomatoid malformation type II.

We report a 7-day-old boy referred to our institution with tachypnea and cardiomegaly who was discovered to have an intrapericardial extra-lobar pulmonary sequestration containing a cystic pulmonary adenomatoid malformation type II. He underwent successful surgical resection of the intrapericardial mass, which we believe represents the first reported case of this rare entity.

Bronchopulmonary Sequestration↗
PubMed2006

Rapid ventricular remodeling with left ventricular unloading postventricular assist device placement: new insights with strain imaging.

We report the case of a 6-year old girl who presented with severe dilated cardiomyopathy. Cross-sectional echocardiography demonstrated a severely dilated hypokinetic left ventricle with an ejection fraction less than 10%. She developed intractable ventricular tachyarrhythmias and subsequently had a left ventricular assist device implanted. Within 1 week of mechanical support, echocardiography demonstrated dramatic reverse remodeling of the left ventricle with marked improvement in myocardial deformation using strain rate imaging. This report further highlights the potential for rapid remodeling after mechanical support of the failing myocardium.

Cardiomyopathy, Dilated↗
PubMed2006

The spectrum of congenital cardiac malformations encountered in six children with Kabuki syndrome.

We investigated the prevalence and forms of congenital cardiac malformations in six children with Kabuki syndrome. There were three girls and three boys, diagnosed at a median age of 1.7 years, with a range from 0.7 to 11.1 years. Cardiac lesions were present in five children (83%), specifically complete transposition, tetralogy of Fallot, coarctation of the aorta, ventricular septal defect, and patency of the arterial duct. Characteristic dysmorphic findings were noted in all patients, as well as a strong predisposition to severe problems with feeding in the neonatal period, and developmental delay. Cardiologists should be alert to this syndrome in children who present with the aforementioned constellation of findings, as patients with mild expression of Kabuki syndrome may go unrecognized for a considerable time.

Abnormalities, Multiple↗
PubMed2006

Incidental detection of parvovirus myocarditis at time of resection of discrete subaortic stenosis.

We report an asymptomatic 18-month-old boy who underwent surgical resection of the discrete subaortic stenosis. Histopathologic examination of the muscle demonstrated diffuse lymphocytic infiltration of the myocardium. Polymerase chain reaction analysis of blood demonstrated parvovirus. This report highlights that asymptomatic myocarditis may be more prevalent than we realise, and that involvement of the myocardium by parvovirus may be entirely asymptomatic.

Aortic Valve Stenosis↗
PubMed2005

Danon disease as an underrecognized cause of hypertrophic cardiomyopathy in children.

BACKGROUND: Some patients with hypertrophic cardiomyopathy (HCM) or left ventricular hypertrophy also present with skeletal myopathy and Wolff-Parkinson-White (WPW) syndrome; mutations in the gene encoding the lysosome-associated protein-2 (LAMP-2) have been identified in these patients, suggesting that some of these patients have Danon disease. In this study we investigated the frequency of LAMP2 mutations in an unselected pediatric HCM population. METHODS AND RESULTS: LAMP2 was amplified from genomic DNA isolated from peripheral lymphocytes of 50 patients diagnosed with HCM and analyzed by direct DNA sequencing. In 2 of the 50 probands (4%), nonsense mutations were identified. In 1 family the proband initially presented with HCM as a teenager, which progressed to dilated cardiomyopathy (DCM) and heart failure. Skeletal myopathy and WPW were also noted. The teenage sister of the proband is a carrier of the same LAMP2 mutation and has HCM without skeletal myopathy or WPW. The other proband presented with HCM, WPW, and skeletal myopathy as a teenager, whereas his carrier mother developed DCM during her 40s. Skeletal and cardiac muscle sections revealed the absence of LAMP-2 on immunohistochemical staining. CONCLUSIONS: LAMP2 mutations may account for a significant proportion of cases of HCM in children, especially when skeletal myopathy and/or WPW is present, suggesting that Danon disease is an underrecognized entity in the pediatric cardiology community.

Adolescent↗
PubMed2005

Characteristics and outcomes of fetuses with pericardial effusions.

Little is known about the characteristics and outcomes of fetuses with pericardial effusions (PEs); therefore, this study sought to identify factors associated with fetal PEs and the natural histories and outcomes of fetuses with PEs. Large PEs are associated with a greater likelihood of structural heart disease, impaired cardiac function, and chromosomal abnormalities, and PEs with hydrops or extracardiac malformations are associated with death. Most fetal PEs resolve, and fetuses with isolated PEs have a very good prognosis.

Adolescent↗
PubMed2005

Impact of chronic left ventricular preload and afterload on Doppler tissue imaging velocities: a study in congenital heart disease.

BACKGROUND: Doppler tissue imaging (DTI) velocities have been reported to be relatively independent of changes in ventricular loading conditions in adult studies. The clinical impact of altered left ventricular (LV) preload and afterload on DTI velocities in children with congenital heart disease has not been adequately evaluated. The purpose of this study was to evaluate the impact of chronic LV preload and afterload on DTI velocities in children with isolated ventricular septal defect and aortic valve stenosis compared with age-matched normal and abnormal (dilated cardiomyopathy) control groups. METHODS: From an apical 4-chamber view, DTI velocities were obtained at the cardiac base at the lateral mitral annulus, lateral tricuspid annulus, and interventricular septum in early diastole, late diastole, and ventricular systole. RESULTS: The majority of DTI velocities did not change significantly in patients with increased LV preload. Patients with increased LV afterload had significantly decreased systolic and early diastolic DTI velocities at both the lateral mitral annulus and ventricular septum compared with control subjects. Children with dilated cardiomyopathy had significantly decreased DTI velocities at all myocardial annular locations. CONCLUSIONS: We conclude that increases in chronic LV preload do not significantly affect the majority of DTI velocities in children with ventricular septal defects. In addition, significantly increased chronic LV afterload in children with aortic valve stenosis is associated with decreased DTI velocities in the absence of other identifiable abnormalities of LV function. Decreased DTI velocity may be secondary to increased afterload or may alternatively be an early marker of subclinical LV longitudinal dysfunction.

Adolescent↗
PubMed2005

Altered expression of dystrophin within the thoracic aorta in coarctation.

Although persisting endothelial dysfunction has been established in the vasculature of patients following surgical repair of coarctation, it is unknown whether there are alterations in the cytoskeleton of the aorta in such patients. We compared staining of N-terminus dystrophin in the smooth muscle of the aortic wall of a patient with coarctation to that in a patient without coarctation, the latter undergoing surgical treatment of a double aortic arch. There was a marked difference in the pattern of expression of dystrophin between the two, with the coarcted specimen demonstrating marked fragmentation but normal intensity of staining. As far as we are aware, ours is the first report to demonstrate the presence of dystrophin in the smooth muscle of the aorta. Alterations in the cytoskeletal structure may account for underlying aberrations in endothelial function in such patients, and is a topic that warrants further investigation.

Aorta, Thoracic↗
PubMed2005

Preterm infants with congenital heart disease and bronchopulmonary dysplasia: postoperative course and outcome after cardiac surgery.

OBJECTIVE: Success in treatment of premature infants has resulted in increased numbers of neonates who have bronchopulmonary dysplasia (BPD) and require surgical palliation or repair of congenital heart disease (CHD). We sought to investigate the impact of BPD on children with CHD after heart surgery. METHODS: This was a retrospective, multicenter study of patients who had BPD, defined as being oxygen dependent at 28 days of age with radiographic changes, and CHD and had cardiac surgery (excluding arterial duct ligation) between January 1991 and January 2002. Forty-three infants underwent a total of 52 cardiac operations. The median gestational age at birth was 28 weeks (range: 23-35 weeks), birth weight was 1460 g (range: 431-2500 g), and age at surgery was 2.7 months (range: 1.0-11.6 months). Diagnoses included left-to-right shunts (n = 15), conotruncal abnormalities (n = 13), arch obstruction (n = 6), univentricular hearts (n = 4), semilunar valve obstruction (n = 3), Shone syndrome (n = 1), and cor triatriatum (n = 1). RESULTS: Thirty-day survival was 84% with 6 early and 6 late postoperative deaths. Survival to hospital discharge was 68%. There was 50% mortality for patients with univentricular hearts and severe BPD. The median duration of preoperative ventilation was 76 days (range: 2-244 days) and of postoperative ventilation was 15 days (range: 1-141 days). The median duration of cardiac ICU stay was 7.5 days (range: 1-30 days) and of hospital stay was 115 days (range: 35-475 days). Current pulmonary status includes on room air (n = 14), O2 at home (n = 4), and ventilated at home (n = 4) or in hospital (n = 4), and 5 patients were lost to follow-up. CONCLUSIONS: BPD has significant implications for children who have CHD and undergo cardiac surgery, leading to prolonged ICU and hospital stays, although most survivors are not O2 dependent. Postoperative mortality was highest among patients with univentricular hearts and severe BPD. Optimal timing of surgery and strategies to improve outcome remains to be delineated.

Bronchopulmonary Dysplasia↗
PubMed2004

Risk factors for aortic valve dysfunction in children with discrete subvalvar aortic stenosis.

Aortic regurgitation (AR) is a known complication of discrete subvalvar aortic stenosis (DSS), and its detection often triggers referral for surgery. However, risk factors for aortic valve dysfunction in children with DSS remain incompletely defined. The primary goal of this study was to determine independent risk factors for moderate or severe AR at mid-term follow-up in patients with DSS. Clinical records and echocardiograms of 220 patients with DSS (109 patients had DSS resection and 111 had no surgery) were analyzed. The primary outcome variable was AR grade (based on the width of the vena contracta) at latest follow-up. Age at diagnosis, gender, and duration of follow-up (median 7.2 years, range 1 to 20.4) did not differ significantly between medical and surgical patients. By multivariate analysis, independent risk factors for moderate to severe AR (n = 30) were older age at diagnosis of DSS (odds ratio [OR] for age > or =17 years 5.13, p = 0.024), previous balloon or surgical aortic valvuloplasty (OR 19.6, p <0.001), and a longer follow-up period (OR for 1-year increase 1.15, p = 0.032). Excluding patients with previous surgical or balloon aortic valvuloplasty, a higher maximal Doppler gradient was an independent risk factor for moderate to severe AR (OR for peak gradient > or =50 mm Hg 10.8, p = 0.001). Independent predictors of low-risk patients (none or trivial AR and peak gradient < or =30 mm Hg) included thin and mobile aortic valve leaflets (OR 7.86, p = 0.006) and an associated ventricular septal defect (OR 2.18, p = 0.019). These clinical and echocardiographic variables can be used to stratify risk of aortic valve dysfunction in patients with DSS and aid in timing of surgical resection.

Adolescent↗
PubMed2004

Arginine vasopressin levels are elevated and correlate with functional status in infants and children with congestive heart failure.

BACKGROUND: Arginine vasopressin (AVP) is a vasoactive hormone that acts on the kidney to conserve solute-free water and produces a potent vasoconstrictive effect during hypovolemic states. AVP levels are elevated in adults with congestive heart failure (CHF), and early clinical trials using AVP antagonists are being conducted. The purpose of this study was to determine if AVP levels (1) are elevated in children with CHF attributable to left ventricular dysfunction or pulmonary overcirculation attributable to large left-to-right shunts and (2) can predict functional clinical status. METHODS AND RESULTS: AVP levels were measured in patients with dilated cardiomyopathy (DCM) and CHF and in patients with large left-to-right intracardiac shunts. Each patient with DCM (ejection fraction percent <40%) was classified as NYHA functional class I through IV when the AVP level was drawn. Serum sodium was measured, serum osmolality was calculated, and echocardiograms and chest radiographs were performed on all study patients. AVP levels were also measured in age-matched controls. Mean AVP level in children with DCM (n=27) was 10.3 pg/mL (+/-12.8) versus 3.7 pg/mL (+/-2.4) in controls (n=15) (P<0.01). Mean AVP level in children with left-to-right shunts (n=14) was 13.9 pg/mL (+/-17.3) versus 3.5 pg/mL (+/-1.3) in controls (n=8) (P<0.04). In patients with DCM, AVP levels correlated directly with NYHA functional class (r2=0.73, P<0.001). CONCLUSIONS: Arginine vasopressin levels are elevated in infants and children with CHF attributable to left ventricular dysfunction and in infants with large left-to-right intracardiac shunts. Furthermore, there is a direct relationship between AVP level and the severity of heart failure in patients with DCM.

Arginine Vasopressin↗
PubMed2004

Characterization of left ventricular diastolic function by tissue Doppler imaging and clinical status in children with hypertrophic cardiomyopathy.

BACKGROUND: Conventional transmitral Doppler indices are unreliable in assessing clinical status in patients with hypertrophic cardiomyopathy (HCM) because they are affected by loading conditions. This study sought to determine whether tissue Doppler velocities are predictive of adverse clinical outcomes including death, cardiac arrest, ventricular tachycardia (VT), significant cardiac symptoms, and exercise capacity in children with HCM. METHODS AND RESULTS: We studied 80 consecutive children (median age 12 years, median follow-up 26 months) evaluated at 1 hospital from January 1999 to August 2003 compared with 80 age- and gender-matched controls. Patients underwent echocardiography, ambulatory Holter monitoring, and upright exercise testing. Children with HCM had significantly decreased early diastolic tissue Doppler velocities at the lateral mitral (13.2 versus 19.3 cm/s), tricuspid (13.3 versus 16.3 cm/s), and septal (9.4 versus 13.5 cm/s) annuli compared with controls (P<0.001 for each comparison). By forward stepwise regression analysis, early transmitral left ventricular filling velocity (E)/septal Ea ratio predicted death, cardiac arrest, or VT (r=0.610, R2=0.37, P<0.001). Peak oxygen consumption (VO2) was most predictive of children who developed symptoms (r=0.427, R2=0.182, P<0.001). Peak VO2 correlated inversely with E/Ea septal ratio (r=-0.740, P<0.01). CONCLUSIONS: Transmitral E/septal Ea ratio predicts children with HCM who are at risk of adverse clinical outcomes including death, cardiac arrest, VT, and significant cardiac symptoms. Peak VO2 correlated with peak exercise capacity in HCM patients.

Adolescent↗
PubMed2004

Impact of cardiac growth on Doppler tissue imaging velocities: a study in healthy children.

BACKGROUND: Doppler tissue imaging (DTI) is a useful modality to quantitatively assess regional myocardial function. Studies attempting to establish reference values for DTI velocities in healthy children have been limited by small sample sizes and limited age distribution. In addition, the clinical effect of cardiac growth and other demographic and echocardiographic parameters on DTI velocities during childhood has not been adequately evaluated. METHODS: Pulsed wave DTI velocities were obtained in 325 healthy children at the lateral mitral annulus, interventricular septum, and lateral tricuspid annulus during early diastole, late diastole, and ventricular systole and were compared with demographic and echocardiographic study variables. RESULTS: In healthy children, parameters of cardiac growth, most notably left ventricular end-diastolic dimension, have the most significant correlation with the majority of DTI velocities. Age was also significantly correlated with most DTI velocities whereas sex, heart rate, and other echocardiographic parameters demonstrated minimal or no correlation. CONCLUSIONS: This study establishes reference values for DTI velocities and demonstrates the important clinical effects of cardiac growth and age on DTI velocities in neonates and children.

Adolescent↗
PubMed2003

Clinical characterization of left ventricular noncompaction in children: a relatively common form of cardiomyopathy.

BACKGROUND: Left ventricular noncompaction (LVNC) is a reportedly uncommon genetic disorder of endocardial morphogenesis with a reportedly high mortality rate. The purpose of this study was to identify the clinical characteristics of children with LVNC. METHODS AND RESULTS: We retrospectively reviewed 36 children with LVNC evaluated at Texas Children's Hospital (TCH) from January 1997 to December 2002. Five children had associated cardiac lesions. There were 16 girls and 20 boys. The median age at presentation was 90 days (range, 1 day to 17 years). The median duration of follow-up was 3.2 years (range, 0.5 to 12 years). Twenty-seven patients (75%) had ECG abnormalities, most commonly biventricular hypertrophy (10 patients, 28%). Both ventricles were involved in 8 patients (22%) and only the left ventricle in 28 patients (78%). Left ventricular systolic function was depressed in 30 patients (83%), with a median ejection fraction of 30% (range, 15% to 66%) at diagnosis. Nine patients presenting in the first year of life with depressed left ventricular contractility had a transient recovery of function; however, ejection fraction deteriorated later in life, at a median interval of 6.3years (range, 3 to 12 years). Two patients had an "undulating" phenotype from dilated to hypertrophic cardiomyopathy. Two patients (6%) were identified with an underlying G4.5 gene mutation. Five patients (14%) died during the study. CONCLUSIONS: LVNC does not have an invariably fatal course when diagnosed in the neonatal period. A significant number of patients have transient recovery of function followed by later deterioration, which may account for many patients presenting as adults, some manifesting an "undulating" phenotype.

Acyltransferases↗