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Biomedical subjects

A Nir

Publications and source records attributed to A Nir.

At least 19 recordsLinked to original sources
PubMed2002

Use of tissue velocity imaging in the diagnosis of fetal cardiac arrhythmias.

BACKGROUND: Precise diagnosis of cardiac arrhythmias in the fetus is crucial for a managed therapeutic approach. However, many technical, positional, and gestational age-related limitations may render conventional methods, such as M-mode and Doppler flow methodologies, or newer techniques, such as fetal electrocardiography or magnetocardiography, difficult to apply, or these techniques may be unsuitable for the diagnosis of fetal arrhythmias. METHODS AND RESULTS: In this prospective study, we describe a novel method based on raw scan-line tissue velocity data acquisition and analysis. The raw data are available from high-frame-rate 2D tissue velocity images and allow simultaneous sampling of right and left atrial and ventricular wall velocities to yield precise temporal analysis of atrial and ventricular events. Using this timing data, a ladder diagram-like "fetal kinetocardiogram" was developed to diagram and diagnose arrhythmias and to provide true intervals. This technique was feasible and fast, yielding diagnostic results in all 31 fetuses from 18 to 38 weeks of gestation. Analysis of various supraventricular and ventricular arrhythmias was readily obtained, including arrhythmias that conventional methods fail to diagnose. CONCLUSIONS: The fetal kinetocardiogram opens a new window to aid in the diagnosis and understanding of fetal arrhythmias, and it provides a tool for studying the action of antiarrhythmic drugs and their effects on electrophysiological conduction in the fetal heart.

Arrhythmias, Cardiac↗
PubMed2001

Propofol does not modify the hemodynamic status of children with intracardiac shunts undergoing cardiac catheterization.

Immobility and cardiovascular stability are required for cardiac catheterization. Pediatric patients need a type of sedation that also allows spontaneous ventilation without supplemental oxygen. Propofol has been adequate in hemodynamically stable patients with congenital heart disease undergoing cardiac catheterization. However, mild systemic hypotension caused by propofol may increase a preexisting right-to-left shunt. The aim of this study is to evaluate, in pediatric patients scheduled for cardiac catheterization, the effects of propofol on systemic and pulmonic circulations. Fifteen patients aged 18 months to 9 years were studied. After a fast of 4-6 hours for solid food, the patient arrived at the cardiac catheterization suite, where an IV catheter was placed. Usual monitoring was used. For sedation, without supplemental oxygen, patients received 1 mg/kg of fentanyl followed by propofol (1-2 mg/kg) titrated to immobility during preparation of the groin. A continuous infusion of propofol (100 mg/kg/min) was also started to obtain immobility during the procedure. Hemodynamic data, including systemic venous, pulmonary artery and vein, aortic saturations, and pressures, were recorded; Qp and Qs were calculated. The same set of data was re-corded 4 minutes after discontinuation of propofol and when the patient was responding to tactile stimuli. Despite lower pressures during propofol infusion, as compared with those pressures measured after discontinuation of propofol, the extent of the intracardiac shunt remained unchanged. Propofol seems to be an adequate sedative agent for pediatric patients undergoing cardiac catheterization, including those with intracardiac shunts.

Anesthetics, Intravenous↗
PubMed2001

Rhabdomyoma in the fetus: illustration of tumor growth during the second half of gestation.

Rhabdomyomata are the most common cardiac tumors in childhood and are associated with tuberous sclerosis. These tumors tend to regress in the first years of life. Little is known about their intrauterine growth pattern. We describe three fetuses with cardiac rhabdomyomata and illustrate the tumor growth by serial echocardiographic views during the second half of gestation. Tumor growth is proportional to cardiac growth and tends to be somewhat slower toward the end of pregnancy.

Adult↗
PubMed2001

Opposing effects of endothelin-1 on C-type natriuretic peptide actions in rat cardiomyocytes.

C-type natriuretic peptide (CNP) and Endothelin-1 are paracrine peptides with opposing vascular and mitogenic actions. In cardiac myocytes, CNP reduced contractility and induced accumulation of cyclic guanosine monophosphate (cGMP). Endothelin-1 caused an increase in contractile amplitude, abolished the negative inotropic effect of CNP, reduced the negative inotropic effect of a membrane permeable cGMP, and inhibited cGMP accumulation induced by CNP. We conclude that endothelin-1 abolishes the negative inotropic effect of CNP. This effect may be mediated by inhibition of the negative inotropic actions of cGMP as well as by reduction of cGMP levels.

Animals↗
PubMed2001

C-type natriuretic peptide has a negative inotropic effect on cardiac myocytes.

C-type natriuretic peptide (CNP) has vasodilatory and antimitogenic actions, but its role in the control of cardiac function is unclear. We studied the effect of CNP on cultured, beating neonatal rat cardiac myocytes. CNP caused a significant reduction in the amplitude of contraction and a significant accumulation of intracellular cyclic GMP. The effect of a membrane permeable cyclic GMP on cell contraction was similar to that of CNP. CNP caused no change in Ca2+ transients. Blockade of natriuretic peptide receptors abolished the effects of CNP on contraction and accumulation of intracellular cyclic GMP. Blockade of cyclic GMP-dependent protein kinase abolished the effect of CNP on myocyte contraction. We conclude that CNP has a negative inotropic effect on neonatal rat cardiac myocytes. The effect of CNP is mediated via natriuretic peptide receptor(s) causing elevation of intracellular cyclic GMP which possibly activates protein kinase and causes attenuation of myofilament sensitivity to Ca2+.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed2001

Association between increased central venous pressure and hydrocephalus in children undergoing cardiac catheterization. A prospective study.

OBJECTS: The relationship between increased central venous pressure (CVP) and development of hydrocephalus has been extensively discussed in the neuropediatric literature. However, the possibility of a direct connection has not been systematically examined. The purpose of this prospective study was to examine whether there was a correlation between elevated CVP and hydrocephalus in children undergoing cardiac catheterization. METHODS: We used cardiac catheterization to measure the right atrial and superior vena caval pressure in 37 children (mean age 30 months) with congenital heart malformations. The children had CVP higher than normal (mean 10.2+/-3.1 mmHg, range 4-18). To evaluate the size of the lateral and fourth ventricles, we performed CT scans of the brain on each child. Abnormal scans were found in 15/37 children, showing brain atrophy (12/37), ventriculomegaly (3/37), and focal infarction (1/37). Cerebral atrophy was more likely to occur in young children (P<0.001). The average head circumference among these children was less than 2SD below the mean for healthy children of comparable ages. Using a correlation coefficient regression model, no relationship was found between CVP and ventricular diameters or head circumference. CONCLUSIONS: These results argue against the hypothesis that mild to moderately elevated venous pressure is involved in the mechanism and development of pediatric hydrocephalus.

Cardiac Catheterization↗
PubMed2001

Use of high-frame rate imaging and doppler tissue echocardiography in the diagnosis of fetal ventricular tachycardia.

Ventricular tachycardia has rarely been diagnosed in the fetus. We describe a 31-week-old fetus with ventricular tachycardia and severely depressed ventricular function. M-mode and 2-dimensional Doppler tissue echocardiography were used in this study to assess the nature of the arrhythmia. The complete atrioventricular dissociation inherent to the diagnosis of ventricular tachycardia was particularly easy to detect with M-mode Doppler tissue echocardiography. Moreover, the onset and the pattern of propagation of the ventricular arrhythmia could be easily identified with 2-dimensional Doppler tissue echocardiography. Doppler tissue echocardiography facilitates the diagnosis of ventricular tachycardia and adds new information that is not available by other techniques.

Adult↗
PubMed2001

Parental knowledge and views of pediatric congenital heart disease.

BACKGROUND: Parental knowledge of their child's heart disease, while often overlooked, contributes to compliance and reduces anxiety. Prior studies have shown that 36% of parental diagnostic descriptions are incorrect. OBJECTIVES: To assess parental knowledge and attitudes among outpatients at a hospital pediatric cardiology clinic. METHODS: Seventy-four families completed a questionnaire in which they described their child's condition and stated their attitude towards dental hygiene and future prenatal diagnosis. RESULTS: Eighteen percent of the parents failed to describe their child's malformation correctly. We found that parental understanding of the heart defect correlated with parental education. Future prenatal diagnosis was considered by 88% of families, and termination of pregnancy by 40%. Only 40% of children were aware of their heart problem. Children of parents who were ignorant about the condition tended to lack knowledge themselves. An additional finding was that 68% of Jewish families turn to non-medical personnel for medical advice--an interesting finding not hitherto addressed. CONCLUSIONS: Ignorance of their child's problem did not correlate with its severity or complexity but rather with parental background: the less educated the parent, the more likely was the problem perceived incorrectly.

Abortion, Therapeutic↗
PubMed2000

The coronary sinus in the fetus.

INTRODUCTION: The normal coronary sinus drains venous blood from the cardiac veins to the right atrium. In some instances, the coronary sinus may be dilated due to volume or more rarely pressure overload. AIMS: To assess the feasibility of detecting the coronary sinus in the fetus and to establish the normal values of the coronary sinus dimensions throughout gestation. SUBJECTS AND METHODS: Fetal echocardiography was performed in 78 normal fetuses from the 16th to the 40th week of gestation (median 25 week). The coronary sinus was measured in four-chamber view (87% of cases) or in parasternal short axis view equivalent (13%). A second group of nine fetuses with a dilated coronary sinus was compared to the normal group. RESULTS: Adequate imaging of coronary sinus was obtained in 97.4% of the normal fetuses. The diameter of the coronary sinus ranged from 1 to 3.2 mm (2 mm +/- 0.13 mm, mean +/- 5% confidence interval) and correlated well with the age of pregnancy (r = 0.86). The length-to-diameter ratio of 24% (+/- 6%) did not vary throughout pregnancy. All nine fetuses with a dilated coronary sinus had a persistent left superior vena cava which drained into it. The diameter of the coronary sinus was approximately three times larger in the abnormal group with a diameter-to-length ratio of approximately 83% (P < 0.0001). CONCLUSION: The coronary sinus is readily identified in the fetus. It gradually increases during pregnancy. An abnormal coronary sinus is easily diagnosed and should prompt the sonographer to look for a persistent left superior vena cava.

Coronary Vessels↗
PubMed2000

Significance of a cardiac murmur as the sole clinical sign in the newborn.

A cardiac murmur is a very common finding in the first few days of life. It is traditionally believed that lesions creating left-to-right shunts do not present so early. This study was aimed to define and to classify the causes of a murmur in a newborn with an otherwise normal examination. All echocardiograms performed on newborns aged 1-5 days who were referred for evaluation of a murmur in a 3-year period were reviewed. Newborns with additional clinical signs or antenatal diagnosis of a cardiac disease were excluded. Of 20,323 live births, there were 170 newborns referred for echocardiogram solely because of a murmur. Of these, 147 (86%) were found to have structural heart defects. The most common lesions found were those creating left-to-right shunts (66%). Ventricular septal defect was the most common single lesion (54/147, 37%), followed by patent ductus arteriosus (34 newborns, 23%). The combination of both was found in 10 newborns (7%). Six newborns (4%) had pulmonary valve stenosis and three (2%) aortic valve stenosis. Seven newborns (5%) had unforeseen complex heart disease. For five of them, delayed diagnosis would have resulted in potentially life-threatening conditions. There was no correlation between the category of lesion and the age of presentation. The audible threshold of a murmur correlated with a maximum instantaneous gradient of 25 mm Hg (range 11-46 mm Hg). Thirteen percent of newborns with isolated heart murmur had no identifiable structural heart disease. These data suggest that most asymptomatic newborns presenting with a murmur in the first days of life have structural heart disease. Some of the more serious defects would not have been diagnosed without early echocardiography. A left-to-right shunt, particularly a ventricular septal defect, may cause a murmur even the first day of life and is probably more common that has been acknowledged.

Aortic Valve Stenosis↗
PubMed1999

Agenesis of tibia with ectrodactyly/Gollop-Wolfgang complex associated with congenital heart malformations and additional skeletal abnormalities.

We report on a child with bifid femur, absent tibiae, hypoplastic hallux, bilateral club feet, congenital heart defects, and segmentation anomalies of the spine and ribs. Parents are consanguineous, from a region where other consanguineous families with similarly affected individuals have been reported. Clinical and genetic controversies of the tibial aplasia-ectrodactyly syndrome/Gollop-Wolfgang complex are discussed.

Femur↗
PubMed1997

Echocardiographic sign for cerebral ischemia.

We describe a newborn who underwent balloon dilatation of critical aortic stenosis and surgical correction of coarctation of the aorta. Postoperative Doppler echocardiogram revealed diastolic retrograde flow in the distal aortic arch and increased systolic flow as well as diastolic forward flow in the left common carotid artery. Cranial computed tomography suggested increased left middle cerebral artery flow and a subacute infarction with luxury perfusion and damage to the blood brain barrier. Therefore, in the absence of another reason for diastolic "run-off" in the distal aortic arch, this flow pattern may represent the echocardiographic sign for cerebral hyperemia associated with subacute ischemia.

Aortic Coarctation↗
PubMed1997

Emotion regulation in mother-child narrative co-construction: associations with children's narratives and adaptation.

The associations were studied between early mother-child co-construction of a separation-reunion narrative and children's concurrent and later (a) emotion narratives and (b) behavior problems. Fifty-one children and their mothers were observed during a co-construction task when the children were age 4 1/2. At ages 4 1/2 and 5 1/2, children's narratives were elicited using the MacArthur Story-Stem Battery (MSSB), and mothers completed the Child Behavior Checklist. Results showed that children who were more emotionally coherent during the co-constructions had MSSB narratives that were more coherent, had more prosocial themes, and had fewer aggressive themes at ages 4 1/2 and 5 1/2. Moreover, such children had fewer behavior problems at both ages. The relations between narrative processes and emotion regulation are discussed.

Adult↗
PubMed1996

Angiotensin converting enzyme inhibition modulates endogenous endothelin in chronic canine thoracic inferior vena caval constriction.

Endothelin (ET) is a potent vasoconstrictor peptide which is elevated in plasma in congestive heart failure. Recent studies suggest an important role for angiotensin II (AII) in the activation of ET in cultured cardiomyocytes. Chronic thoracic inferior vena caval constriction (TIVCC) is a model of reduced cardiac output that mimics the neurohumoral activation observed in congestive heart failure. We hypothesized that activation of the renin-angiotensin system in TIVCC plays a role in the activation of ET and that the elevation of endogenous ET contributes to the systemic and renal vasoconstriction that characterizes this model of venous congestion. We studied conscious dogs after 7 d of TIVCC in the presence or absence of chronic angiotensin converting enzyme inhibition with enalapril. TIVCC resulted in marked activation of plasma AII and ET in plasma, right atrium, lung, and renal medulla which was further localized to cardiomyocytes, pulmonary, and renal epithelial cells. Chronic angiotensin converting enzyme inhibition abolished the increases in plasma AII and ET during TIVCC. Acute endothelin A receptor blockade with FR-139317 resulted in significant decreases in mean arterial pressure and systemic vascular resistance in TIVCC. We conclude that activation of the renin-angiotensin system contributes to the activation of circulating and local ET in TIVCC and that this activation plays an important role in the regulation of arterial pressure and systemic vascular resistance in this model of congestive failure.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1995

Tuberous sclerosis and cardiac rhabdomyoma.

We conclude that echocardiographically detected cardiac rhabdomyomata are common in patients with tuberous sclerosis complex, and are more prevalent and prominent in the younger patient. Tumors regress in size or number, or both, in most patients aged < 4 years, and less so in older patients. Cardiac rhabdomyomata are associated with a higher incidence of preexcitation and may increase the risk for arrhythmia.

Adolescent↗