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Biomedical subjects

B Marcus

Publications and source records attributed to B Marcus.

27 records · Page 2Linked to original sources
PubMed1991

Normal thymus simulating pericardial disease: diagnostic value of magnetic resonance imaging.

Normal enlargement of the thymus in infancy can often lead to erroneous clinical suspicion of cardiomegaly. Roentgenographic differentiation is not always definitive but echocardiography is generally effective in differentiating cardiac pathology from an enlarged thymus. In this patient, magnetic resonance imaging was necessary to differentiate benign thymic hyperplasia from pericardial or mediastinal pathology. Thymic involution with a severe neonatal illness, followed by thymic rebound, which later subsided, added to the interest and initial confusion in this patient.

Cardiomegaly↗
PubMed1990

Intrinsic heart rate in children and young adults: an index of sinus node function isolated from autonomic control.

Standard evaluation of children with sinus node (SN) dysfunction cannot distinguish abnormal autonomic tone from intrinsic SN disease. This distinction has potentially important therapeutic and prognostic implications. Intrinsic heart rate (IHR)--the peak heart rate (HR) measured during pharmacologic combined autonomic blockade--reflects intrinsic SN function. The purpose of this study was to evaluate the use of IHR--and its relationship with resting heart rate (RHR)--in distinguishing autonomic influence from intrinsic SN disease among children with SN dysfunction. IHR was determined in the electrophysiology laboratory using intravenous propranolol, 0.2 mg/kg, followed by intravenous atropine, 0.04 mg/kg; the peak HR recorded was the IHR. IHR was measured in two groups. Seven control subjects, defined as patients with normal noninvasive SN testing, had IHR mean of 128 +/- 24 beats/min; this was greater than RHR mean of 89 +/- 16 beats/min (p less than 0.01). Eight patients with abnormal noninvasive SN testing had IHR mean of 103 +/- 6 beats/min; this was greater than RHR mean of 71 +/- 9 beats/min (p less than 0.01). We therefore reached the following conclusions. (1) Among this particular group of patients with abnormal noninvasive SN testing, IHR was consistently in the normal range for age and greater than RHR, suggesting that excess vagal tone can play a significant role in the expression of SN dysfunction. (2) Among normal individuals, IHR is age-related, decreasing with advancing age. IHR greater than RHR suggests that vagal tone predominates in the normal resting state as the net increase in HR during combined autonomic blockade is due to blockade of vagally mediated chronotropic inhibition.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

Utility of Doppler echocardiography in the evaluation of aortic homograft valved conduit function in children: need for segmental conduit interrogation.

To assess the utility of Doppler echocardiography in evaluation of aortic homograft valved conduit function, 10 consecutive pediatric patients had Doppler examination of aortic homograft valved conduits associated with follow-up cardiac catheterization. General correlation was found between the Doppler-derived peak systolic pressure gradient across the aortic homograft valved conduit and cardiac catheterization (r = 0.65, P less than 0.05, SEE = 20.5). One patient with multilevel obstruction had significant underestimation of gradient by Doppler due to incomplete segmental interrogation of the aortic homograft valved conduit. For the other nine patients with complete segmental conduit interrogation, correlation between Doppler and cardiac catheterization was excellent (r = 0.93, P less than 0.01, SEE = 10). Conduit insufficiency in nine out of ten patients was graded qualitatively using Doppler color flow mapping with excellent correlation between color flow mapping and cardiac catheterization (r s = 98). Aortic homograft valved conduit function can be accurately noninvasively assessed by Doppler but proximal, valve, and distal conduit segmental interrogation is necessary to localize site of obstruction if present, rule out multilevel obstruction, and avoid underestimation of systolic gradient.

Adolescent↗
PubMed1990

Comparison between bronchial response to inhaled hypoosmolar and isoosmolar solutions of sodium cromoglycate after exercise challenge.

The effectiveness of a sodium cromoglycate isoosmolar solution (288 mOsmol/L) versus hypoosmolar commercial solution (40 mOsmol/L) was studied in 14 asthmatic children with exercise-induced asthma. The mean FEV1 after exercise in patients pretreated with a sodium cromoglycate hypotonic solution compared with FEV1 at rest was -2% +/- 10%. The mean FEV1 after exercise in patients pretreated with an isotonic solution compared with FEV1 at rest was 3% +/- 6%. This statistically significant difference (P less than .01) proves that the effectiveness of sodium cromoglycate can be improved by raising the osmolarity to isotonic levels.

Administration, Inhalation↗
PubMed1985

Effects of atenolol on exercise capacity in patients with mitral stenosis with sinus rhythm.

Exercise capacity is frequently impaired in patients with mitral stenosis (MS) and sinus rhythm (SR). The resulting increased heart rate, which shortens the diastolic filling period, and the increased cardiac output lead to further elevations of left atrial pressure and subsequent pulmonary congestion. The effect of the beta-receptor blocking agent atenolol, 100 mg/day, was assessed in 13 patients with MS and SR. Exercise performance was assessed using a modified multistage Bruce protocol after 2 weeks of placebo and after 2 weeks therapy with atenolol in a single-blind, crossover, placebo-controlled, randomized study. Atenolol resulted in significant decreases in mean heart rates at rest and during exercise (p = 0.0015) and a significant increase in total exercise time (p = 0.0015). Maximal exercise capacity was also significantly improved (p = 0.0015). All patients were both objectively and subjectively improved by atenolol. Thus, beta-blockade with atenolol improves exercise capacity in patients with MS and SR and may be of benefit to most such patients. The improved effort tolerance is attributed to reduction of the exercise-associated sinus tachycardia by beta-blockade, allowing a longer diastolic filling period and better left atrial decompression.

Adolescent↗
PubMedDate not supplied

Echocardiographic detection of left circumflex coronary artery to left superior vena cava fistula by use of Doppler color flow mapping.

We report the two-dimensional and Doppler color flow mapping echocardiographic findings in a neonate with left circumflex coronary arteriovenous fistula to a left superior vena cava. Doppler color flow mapping, in concert with detailed imaging, was essential to identify this rare fistula and to prepare for therapeutic intervention at initial cardiac catheterization.

Arteriovenous Fistula↗
PubMedDate not supplied

Outpatient transesophageal echocardiography with intravenous propofol anesthesia in children and adolescents.

Outpatient transesophageal echocardiography (TEE) was performed in 10 children and adolescents (aged 3 to 19.5 years, mean 13.5 years; weight 12 to 91 kg, mean 49 kg), including two with Down's syndrome and one with autism, for diagnostic evaluation of issues unresolved by transthoracic echo examination (TTE). Issues for TEE: evaluation for atrial septal defect (two patients); anatomy of left ventricular outflow tract obstruction (one patient); aortic valve anatomy before valvuloplasty for insufficiency (one patient); evaluation for cause of cyanosis after Fontan operation (one patient); determination of source of high-velocity intracardiac turbulence after atrioventricular septal defect repair (one patient); rule out cardiac embolic source in patient with stroke (one patient); evaluate prosthetic valve function and rule out thrombus (one patient); determination of anatomic relationship of mitral valve to a ventricular septal defect before surgery for complex cyanotic heart disease (one patient); and evaluation for aortic dissection in Marfan's syndrome (one patient). Intravenous propofol anesthesia administered without endotracheal intubation by an anesthesiologist allowed successful outpatient TEE in nine patients; midazolam-conscious sedation was used in one. Outpatient TEE resolved diagnostic issues in all patients without complication, thereby avoiding cardiac catheterization in six patients and supplementing catheterization for preoperative planning in four patients. TEE can be performed safely and effectively with propofol anesthesia in the outpatient setting in carefully selected children and adolescents to provide vital diagnostic information. However, given the invasive nature of the procedure and the use of anesthesia, outpatient pediatric TEE should be used judiciously.

Adolescent↗