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Biomedical subjects

B G Baylen

Publications and source records attributed to B G Baylen.

At least 19 recordsLinked to original sources
PubMed1996

Association of a mosaic chromosomal 22q11 deletion with hypoplastic left heart syndrome.

The atypical presentation of CATCH 22 raises several important concerns. First, in this patient, as in others, the heart defects were found in association with subtle facial abnormalities but with few of the other criteria normally seen in CATCH 22. This association alone may be sufficient to raise suspicion that an interstitial 22q11 deletion may be present. Second, the incidence of chromosome 22 deletions in parents of children with a 22q11 deletion (25%) suggests that siblings or subsequent fetuses may also be at risk. Parents with subtle or unusual manifestations of CATCH 22 may be unaware of their potential carrier status. Finally, the recognition of chromosomal mosaicism in this patient may have been fortuitous, as cytogenetic studies of leukocytes from other individuals with a mosaic karyotype may sometimes fail to reveal a 22q11 deletion that is present in cardiac tissues. Molecular cytogenetic analysis of cardiac specimens that are removed during routine surgical procedures may be warranted in appropriate clinical situations.

Chromosome Deletion↗
PubMed1996

Transvascular catheter infiltration of the ductus arteriosus with formalin in the newborn lamb: a novel method of establishing and maintaining ductal patency.

OBJECTIVES: This study sought to establish and maintain patency of the ductus arteriosus by a new method of transvascular formalin infiltration of the ductus arteriosus wall. BACKGROUND: Maintaining patency of the ductus arteriosus postnatally is necessary with many forms of congenital heart disease to ensure survival until definitive surgical repair. A variety of approaches have to date met with variable success. METHODS: Seven newborn lambs underwent catheterization at 1 to 5 days of age. A functionally closed ductus arteriosus was traversed with a specially designed porous balloon catheter, and the wall was infiltrated with 10% formalin. The ductus was then further dilated with either a 7- or 8-mm diameter balloon. RESULTS: The ductus arteriosus wall was successfully infiltrated and dilated in all animals. Two lambs were euthanized within 24 h with congestive heart failure from a large ductus, and one lamb was electively euthanized 5 days after transvascular infiltration. Four lambs underwent serial follow-up catheterizations, one of which required repeat balloon dilation 47 days after infiltration. At latest follow-up (mean age [+/- 1 SD] 83 +/- 34 days, range 33 to 108), the pulmonary/systemic flow ratio (2.7 +/- 1.2) was unchanged from immediately after infiltration (1.9 +/- 0.5, p > 0.1). The narrowest diameter of the ductus arteriosus (4.3 +/- 0.4 mm vs. 6.9 +/- 2.6 mm, p > 0.1) and its ratio to that of the adjacent descending aorta (0.5 +/- 0.1 vs 0.4 +/- 0.1, p > 0.1) were also unchanged at latest follow-up. No systemic toxicity was observed. At postmortem study, the ductus was patent, and histologic analysis showed variable intimal and medial destruction, endothelial regeneration, loss of elastic tissue and calcification. Adjacent pulmonary artery and aorta were normal. Based on the small sample size and the observed maximal effect size of 70%, the power of the study is at most 40% to detect significant differences. CONCLUSIONS: To our knowledge, this is the first time that transvascular formalin infiltration of the ductus arteriosus wall has been applied successfully to maintain ductal patency in the newborn lamb. This method may provide a means of palliation for neonates with certain forms of congenital heart disease.

Animals↗
PubMed1996

Outcome after open-heart surgery in infants and children.

We have studied the neurodevelopmental outcome of 104 consecutive unselected children who underwent open-heart surgery from 1987 through 1989. Survivors had formal neurologic and psychometric examinations after 2 years of age. Mean IQ was 90, and 78% had scores above 70. Cerebral palsy occurred in 22%. Deep hypothermia for longer than 45 minutes was associated with IQ less than 85 (P < .001) and later cerebral palsy (P = .02). Those less than 1 month old at operation had a median IQ of 96, and 25% had cerebral palsy. Median IQ for survivors of hypoplastic left heart syndrome was 66, only one had an IQ above 70, and 57% had cerebral palsy. Median IQ for transposition of great arteries was 109, only one was less than 85, and all had normal neurologic examinations. Those between 1 and 6 months of age at operation had a median IQ of 93, with 64% above 85, and 5% had cerebral palsy. Those older than 6 months had a median IQ of 99, with 70% above 85, and 13% had cerebral palsy. For infants less than 1 month old at operation, a strong association existed between outcome, type of lesion, and duration of deep hypothermia (P < .01), although not in all cases. In those older than 1 month at operation, no association existed between outcome and any study variable. Although the majority of children have an uneventful outcome after open-heart surgery, a significant morbidity exists. This is related to several factors, including type of lesion and duration of hypothermia, particularly in neonates; preoperative congenital and acquired lesions; and possible perioperative cerebrovascular events.

Age Factors↗
PubMed1995

Postoperative neurologic complications after open heart surgery on young infants.

OBJECTIVE: To ascertain the relation between postoperative neurologic complications and variables occurring before, during, and after hypothermic cardiopulmonary bypass surgery to correct congenital heart disease in young infants. DESIGN: Prospective analysis of mortality and neurologic morbidity before hospital discharge; systematic comparison with patient characteristics, metabolic status, surgery variables; and preoperative neurologic findings of the patients. SETTING: Intensive care unit in tertiary care center. PATIENTS: Consecutive sample of 91 full-term infants who underwent 100 operations between January 1989 through December 1992. Nine infants had more than one operation during the study period. MAIN OUTCOME MEASURES: Levels of alertness, tone, focal signs, dyskinesia, pyramidal signs, seizures, and death. RESULTS: Reduced level of alertness at discharge from the hospital in 19% of patients; seizures in 15% (70% focal); severe hypotonia in 11% before surgery, and in 7% at discharge from hospital; generalized pyramidal findings in six (7%); asymmetry of tone in 5%; and chorea that did not persist in 11%. Results of cranial ultrasound tests were abnormal in 20% of patients. Of these those with abnormal cranial ultrasound examinations 55% were abnormal before surgery. Overall mortality was 18%. Of the patients who died, 59% had interrupted aortic arch or hypoplastic left heart syndrome. Mortality for patients with these lesions was 40%. Alertness (P = .005), chorea (P = .03), and hypotonia (P = .02) were associated with duration of deep hypothermia longer than 60 minutes. No association was found among other outcomes and study variables, except the relation between severe left-sided heart lesions and mortality. CONCLUSIONS: Mortality and neurologic morbidity after open heart surgery on young infants may be due to several factors, including type of lesion, preexisting brain abnormalities, duration of deep hypothermia, and strokes.

Brain↗
PubMed1995

The Norwood operation and subsequent Fontan operation in infants with complex congenital heart disease.

From April 1987 to September 1993, 60 infants underwent a Norwood operation for complex congenital heart disease including hypoplastic left heart syndrome (n = 41), ventricular septal defect and subaortic stenosis with aortic arch interruption/severe coarctation (n = 7), complex single right ventricle with subaortic stenosis (n = 8), critical aortic stenosis with endocardial fibroelastosis (n = 2), and malaligned primum atrial septal defect with coarctation (n = 2). Age at operation ranged from 1 day to 3.9 months (mean 9 days, median 3.5 days). The operative mortality (< 30 days) was 33% (20 patients). Late mortality was 17% (10 patients). Nine of the 20 (45%) operative deaths occurred during the first 2 days after the operation as a result of sudden hemodynamic instability. All four infants with premature closure of the foramen ovale had pulmonary lymphangiectasia and died of pulmonary failure. Seven operative deaths have occurred in 36 patients since 1990 (19%); in the past 2 years, no operative deaths have occurred in 22 patients. Overall, there are 30 long-term survivors (50%). Twenty-one of these 30 infants have undergone a two-stage repair with a modified Fontan operation at 7.3 to 27.6 months of age (mean 18.1 months) with no mortality. Six patients have entered a three-stage repair strategy by undergoing a hemi-Fontan procedure at 6.8 to 23.0 months (mean 8.8 months) with no mortality, and two of these patients have now had their modified Fontan operation at 23.0 to 46.7 months of age with no mortality (four are still awaiting surgery). Two patients have undergone a two-ventricle repair with a Rastelli procedure, with no mortality at 7.4 and 14.1 months of age. Early in our experience, infants undergoing the Norwood operation had a high early mortality most often related to sudden hemodynamic instability. After we instituted a protocol that adds carbon dioxide to the inspired gas during postoperative mechanical ventilation, the postoperative course became more stable and there have been no operative deaths. In summary, the operative mortality for the Norwood operation continues to improve. A subsequent Fontan operation can be performed with excellent clinical results.

Cardiac Surgical Procedures↗
PubMed1994

EEG changes during open heart surgery on infants aged 6 months or less: relationship to early neurologic morbidity.

In a prospective study, we analyzed the intraoperative electroencephalographic (EEG) changes during open heart surgery with deep hypothermia in 66 infants aged 6 months or younger, 70% of whom were neonates. Suppression of amplitude and continuity at the nadir of temperature reduction and following rewarming, and the appearance of periodic paroxysmal activity, was compared with neurologic abnormalities before and following operation, patient characteristics, and operation variables. EEG changes disclosed no relationship to abnormal neurologic findings, age at operation, type of anesthetic, duration of cardiopulmonary bypass (CPB), duration of low-flow CPB or cooling, temperature at circulatory arrest (HCA) or low flow, or nasopharyngeal-venous return temperature differences. EEG suppression following rewarming was associated with the use of thiopentone and duration of HCA. Use of thiopentone was also related to decreased levels of alertness at the end of the first postoperative week. We could not demonstrate any association between operation variables, including duration of HCA, and postoperative neurologic findings which include abnormalities of tone, alertness, seizures, generalized pyramidal signs, choreoathetosis, and hemiparesis. Severe hypotonia before operation was associated with continuing severe hypotonia during the postoperative period. EEG changes during cooling for open heart surgery on infants appear to be physiologic, and these plus EEG suppression following HCA or low-flow CPB are not useful predictors of early neurologic morbidity.

Brain Damage, Chronic↗
PubMed1994

Long-term MRI changes in brain after pediatric open heart surgery.

We performed magnetic resonance imaging (MRI) on the brain and neurologic examinations on 23 children after open heart surgery for congenital heart disease. Twenty children also had psychometric assessments. Examinations were performed at a mean age of 66 months (range, 26 to 180 months). Age at operation was less than 1 month in 43% and more than 6 months in 45%. Abnormal scans were found in 17 (74%) and showed diffuse findings consistent with hypoxic-ischemic encephalopathy, with or without areas of cortical infarction; focal cortical infarction alone; and (in one patient) callosal agenesis and abnormal neuronal migration. Normal IQ and neurologic examinations were found in all six of those who had a normal MRI, and five of six children with changes consistent with focal cortical infarction without diffuse change had a normal neurologic examination. Cerebral palsy and mental retardation was common in the group with diffuse abnormality (in eight of nine children), and this was more likely to occur in those who underwent prolonged (> 45 minutes) hypothermic circulatory arrest and operation during early infancy (P = .004). Focal cortical findings without diffuse changes were more likely in those who underwent open heart surgery without hypothermic circulatory arrest and were older than 6 months at operation, and these children were less likely to have frank neurodevelopmental sequelae. Thus, in our population, focal cortical lesions were common after open heart surgery, and, in addition, diffuse brain abnormality on MRI plus neurologic sequelae were common after prolonged hypothermic circulatory arrest.

Adolescent↗
PubMed1993

Aortic "recoarctation" at rest versus at exercise in children as evaluated by stress Doppler echocardiography after a "good" operative result.

The mechanism for exercise systolic hypertension after a "good" operative repair of coarctation of the aorta remains speculative. Twenty-four children (mean age +/- SD 10.3 +/- 3.8 years) were studied with continuous-wave Doppler echocardiography while they performed continuous, graded, maximal treadmill exercise. Patients were free of "recoarctation" based on conventional resting echocardiography. Measurements of ascending and descending aortic peak instantaneous systolic velocity were obtained at rest, throughout exercise and during recovery. Results were compared with 24 age- and gender-matched control subjects. Fifteen patients were normotensive (group 1) (peak systolic blood pressure, 147 +/- 21 mm Hg) and 9 developed systolic hypertension during exercise (group 2) (196 +/- 32 mm Hg) (p < 0.05) (control subjects, 143 +/- 21 mm Hg). Descending aortic peak systolic velocity at rest ranged from 1.50 +/- 0.27 m/s in the control group to 2.57 +/- 0.57 m/s (group 1) and 2.93 +/- 0.43 m/s (group 2) (p < 0.05, group 2 vs control). Differences were amplified at peak exercise with systolic velocity increasing to 4.26 +/- 0.61 m/s in group 2 but only to 3.61 +/- 0.70 m/s in group 1 and 2.26 +/- 0.38 m/s in control subjects (p < 0.05, group 2 vs group 1 and control). Seven patients developed a descending aortic diastolic velocity during exercise. Stepwise linear regression analysis identified 2 variables to be significant determinants of peak exercise systolic blood pressure in the "total" patient group: (1) age at exercise testing, and (2) descending aortic peak systolic velocity at peak exercise (r2 = 0.88, p < 0.001) (group 2, alone - r2 = 0.98, p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Discrepancies in aortic growth explain aortic arch gradients during exercise.

OBJECTIVES: This study was conducted to evaluate the incidence and etiology of hypertension and aortic arch gradients during exercise in patients who have apparent good coarctation repair assessed at rest. BACKGROUND: The reported incidence of recurrent aortic arch obstruction (rest gradient > 20 mm Hg) after previous successful surgical repair varies from 0% to 60% and usually is associated with recurrent stenosis at the site of surgical repair. METHODS: Maximal treadmill exercise with Doppler echocardiographic gradient estimation was performed in 28 patients with a good coarctation repair at rest (normal blood pressure and arch gradient < 20 mm Hg) who had isolated coarctation repair a mean of 7.8 years previously. RESULTS: Eight (29%) developed systolic hypertension for age and a mean Doppler gradient of 45 +/- 13 mm Hg. At cardiac catheterization, the rest peak to peak systolic gradient (6 +/- 6 to 28 +/- 7 mm Hg, p < 0.001), peak systolic instantaneous gradient (16 +/- 11 to 48 +/- 9 mm Hg, p < 0.01) and cardiac index (3.5 +/- 0.7 to 5.9 +/- 1.1 liters/m per m2, p < 0.001) all increased during isoproterenol infusion. Angiographic systolic aortic arch measurements proximal to the innominate artery, left common carotid artery, left subclavian artery and the narrowest dimension at the coarctation repair site demonstrated hypoplasia at the left common carotid artery (11.8 +/- 1.7 vs. 16.7 +/- 2.9 mm/m2, p < 0.01) and left subclavian artery (11.6 +/- 1.7 vs. 15.4 +/- 3.1 mm/m2, p < 0.05) compared with findings in 10 patients with normal aortograms. Transverse aortic arch ratios were also smaller in the eight patients with abnormal findings. Preoperative angiographic ratios were not predictive of late postoperative findings. CONCLUSIONS: Exercise testing detects hypertension and arch gradients in patients with a good coarctation repair as assessed at rest. The hypertension and arch "obstruction" appear to be related to discrepancies in the growth of the transverse aortic arch proximal to the repair site, rather than a "recoarctation" of the aorta.

Adolescent↗
PubMed1993

Captopril-induced bone marrow suppression in two cardiac patients with trisomy 21.

Neutropenia is an infrequent complication following administration of the angiotensin-converting enzyme (ACE) inhibitor, captopril. Most reports have been in adult patients, with rare reports in the pediatric population. We report two cases of neutropenia following captopril use in cardiac patients with trisomy 21. As this was not seen in patients without Down's syndrome, we postulate that patients with trisomy 21 have bone marrow which is "at risk" for suppression, and, thus warrant close evaluation while on such medications.

Bone Marrow↗
PubMed1993

Developmental differences in cardiac myocyte calcium homeostasis after steady-state potassium depolarization: mechanisms and implications for cardioplegia.

We previously reported developmental differences in the response of cytosolic free calcium ([Cai]) to extracellular potassium ([Kex]) depolarization (cardioplegia) in juvenile (4 weeks post partum) and mature (12 to 18 months post partum) cardiac myocytes (rabbit). Our present study explored the physiologic basis for these observations. Single calcium-tolerant cardiac myocytes were isolated by sequential exposure to proteolytic agents, loaded with a fluorescent probe for calcium (fura-2) and [Cai] measured by standard fluorescence techniques. The response of [Cai] to [Kex] depolarization (30 mmol/L) was determined in the presence of varying levels of extracellular calcium [Caex], verapamil, ouabain, and amiloride. At nominal levels of [Caex] (0 mmol/L), no significant increases in [Cai] from the juvenile (2.1% +/- 3.3%) or mature (8.5% +/- 3.1%) myocytes were seen. At increasing [Caex], there was a progressive increase in the response of [Cai] to [Kex] depolarization in mature animals' cells (191.8% +/- 40.7%) but not in the juveniles' cells (28.0% +/- 11.5%). Exposure to verapamil resulted in an approximate 80% reduction in relative increase in [Cai] in the mature compared with 60% in the juvenile myocytes. Finally, ouabain exposure resulted in a significant increase in the relative change of [Cai] in juvenile cells (30% to 126.4% +/- 39.4%) but not in the adults' cells. This increase in the juvenile myocytes was blocked by amiloride. We conclude that increases in cardiac myocyte [Cai] after [Kex] depolarization occur predominantly through the calcium channel in the mature animal and through sodium-calcium exchange in the juvenile.

Aging↗
PubMed1993

Results of surgical repair of congenital supravalvular aortic stenosis.

Our experience with congenital supravalvular aortic stenosis dates from 1977 to 1991. Thirteen patients, aged 2 days to 38 years (mean 7.6 years, median 3.8 years), had surgical repair of the lesion. The preoperative peak-to-peak systolic gradients ranged from 25 to 110 mm Hg (mean 64 mm Hg). Four patients had trace to mild aortic insufficiency. Surgical repair was accomplished by several techniques that have evolved over time. There was one death in a 2-day-old neonate who also had severe hypertrophic cardiomyopathy. The 12 survivors had postoperative gradients of 0 to 30 mm Hg (mean 10 mm Hg) in the supravalvular region. The mean reduction in gradient was 48 mm Hg. A new technique employing all autologous aortic tissue is described.

Adolescent↗
PubMed1992

The Fontan operation in infants less than 2 years of age.

Young age remains a reported risk factor for a successful Fontan operation despite improved survival rates. Since March 1978, the Fontan operation has been performed in 47 patients. To avoid a primary or secondary palliative shunt, an early Fontan procedure (Group 1: mean age 1.5 +/- 0.5 years, range 0.6 to 2) has been performed in 17 children with the outcome similar to that of the remaining 30 older patients (Group 2: mean age 7.5 +/- 5 years, range 2.4 to 23 years). Preoperatively both groups had acceptable hemodynamic status for a successful Fontan result. Operative variables including cardiopulmonary bypass time, aortic cross-clamp time and core temperature were similar between groups and did not affect mortality. The postoperative mortality rate including early surgical (0% vs. 13%, respectively), late (18% vs. 12%) and total (18% vs. 23%) was similar between Groups 1 and 2 (p greater than 0.05). Immediate postoperative arrhythmias were more frequent in Group 1 (71% vs. 25%, p less than 0.01) with no related mortality, while late arrhythmias occurred with equal frequency (29% vs. 39%, p greater than 0.05). Group 1 infants required a longer hospital stay (22 +/- 9 vs. 14 +/- 5 days, p less than 0.01). Thus, young age is not a risk factor for successful outcome of the Fontan operation in patients with acceptable preoperative hemodynamic status. An early Fontan operation may also avoid prolonged palliative procedures and their potential deleterious effects.

Age Factors↗
PubMed1992

Developmental differences in the response of cytosolic free calcium to potassium depolarization and cardioplegia in cardiac myocytes.

Several biochemical and functional characteristics of immature myocardium suggest a diminished capacity to regulate intracellular Ca2+ during stress. In particular, cellular calcium overload has been postulated as an important pathogenetic mechanism accounting for suboptimal functional recovery following cardioplegia in immature myocardium. Using intracellular Fura-2 fluorescence as Ca2+ indicator, we measured cytosolic free calcium ([Cai]) in single myocytes and cell suspensions derived from both juvenile (4 weeks post-partum) and mature (6-12 months post-partum) New Zealand white rabbits. Resting [Cai] in juvenile heart cells (26 +/- 3 nM) were approximately 50% of that found in adult myocytes (55 +/- 5 nM). In addition, on exposure to increasing concentrations of extracellular potassium ([Kex]), adult but not juvenile myocytes exhibited increases in [Cai]. These two observations underscore developmental differences in intracellular Ca2+ homeostasis. Of particular clinical relevance is the [Cai] response to cardioplegia containing 16 mM [Kex]: neither group demonstrated the expected [Cai] increase in response to potassium depolarization. The lack of [Cai] response to cardioplegia was most likely due to the high levels of Mg2+ (32 mM) contained in cardioplegic solutions. We conclude that cellular calcium overload does not occur following exposure to cardioplegia alone. Accordingly, these findings do not account for recognized developmental differences in functional recovery from "myocardial protection".

Age Factors↗