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Biomedical subjects

S M Yabek

Publications and source records attributed to S M Yabek.

At least 55 records · Page 3Linked to original sources
PubMed1979

Effects of prostaglandin E1 and indomethacin on fetal and neonatal lamb mesenteric artery responses to norepinephrine.

The effects of prostaglandin E1 (PGE1) and indomethacin on isolated fetal and neonatal lamb mesenteric artery responses to norepinephrine were investigated. PGE1 (1.5 micrometer) significantly reduced vasoconstriction responses to 0.5 to 5 micrometer norepinephrine. Indomethacin (1 micrometer) markedly potentiated the constrictor effects of 0.5 to 10 micrometer norepinephrine. PGE1 prevented the potentiating effect of indomethacin. Neither PGE1 nor indomethacin altered basal muscle tension. These results suggest that endogenous PGs modify adrenergic responses in the isolated mesenteric arteries of preterm and newborn lambs.

Animals↗
PubMed1979

Prostaglandin E1 infusion in the hypoplastic left heart syndrome.

Aortic infusion of prostaglandin E1 in a moribund infant resulted in marked clinical improvement. Appropriate studies were conducted and the diagnosis of hypoplastic left heart syndrome was made. Although the outcome was unaltered, the improved clinical condition allowed us to exclude potentially curable defects such as aortic coarctation and interruption.

Aorta↗
PubMed1979

Partial anomalous pulmonary venous connection to the azygous vein with intact atrial septum.

A five-year-old girl with partial anomalous pulmonary venous connection to the azygous vein with intact atrial septum is reported. The clinical and roentgenographic features suggested the correct diagnosis. Surgical correction of this previously unreported defect was accomplished by creating an atrial septal defect and constructing a baffle to direct the blood flow from the azygous vein to the left atrium.

Azygos Vein↗
PubMed1978

Accuracy of echocardiography in assessing left ventricular dimensions and volume.

The accuracy of determining left ventricular function from echocardiography was assessed in 26 children (group I) with cineangiographically-determined normal left ventricular volume (LVV) and 28 children (group II) with large left ventricular volumes. Conventional LV echo dimensions were compared to the cineangiographic LV anterior-posterior minor axis (LVmA) and LVV. Very good correlations were found in group I between LV end-diastolic echo dimensions (LVEDD) and cine LVmA (r = 0.91) and between LVEDD and LV end-diastolic volume (LVEDV) by cine in group I (r = 0.86). In group II correlations were less accurate between LVEDD and diastolic LVmA and between LVEDD and LVEDV. There was poor correlation between the cine and echo percent of shortening (r = 0.41) and velocity of circumferential fiber shortening (VCF) (r = 0.51). This study demonstrates that M-mode echocardiography is a very useful method for determining LV dimensions in children with normal LV volume, but is less accurate in children with left ventricular volume overload or with abnormal septal orientation or postoperative status after ventriculotomy.

Adolescent↗
PubMed1978

Sinus node dysfunction in children, adolescents, and young adults.

Thirty children and young adults with electrocardiographic and clinical evidence of sinus node dysfunction (SND) are described. Ages ranged from 3 days to 25 years. Of these, 10 patients had inappropriate sinus bradycardia, 16 had periods of sinus arrest, and 9 had sinoatrial exit block. A total of 22 patients had significant heart disease and SND developed in 13 after cardiac surgery. Eight patients with SND had no obvious heart disease. Seven patients were symptomatic, having either syncopal (three) or near-syncopal episodes (four). The three with syncope have received permanent demand pacemakers. Although significant SND occurs most frequently in children with congenital heart disease, particularly following corrective cardiac surgery, it may occur in otherwise normal individuals.

Adolescent↗
PubMed1977

Total anomalous pulmonary venous connection. Report of ten cases and review of the literature.

Ten cases of total anomalous pulmonary venous connection, all presenting at or below the age of eight weeks, are presented: three below the diaphragm, two to the coronary sinus, one to the right atrium, three to the left vertical vein, and one to the right superior vena cava. Six patients had other cardiac anomalies, and surgical mortality represented 75%. A review of the subject is presented.

Cardiac Catheterization↗
PubMed1977

Diagnosis of trifasicular damage following tetralogy of fallot and ventricular septal defect repair.

We evaluated the usefulness of the surface electrocardiogram to predict the presence of postoperative trifascicular damage. We used the pre and postoperative electrocardiograms and postoperative His bundle electrograms from 50 patients an average of 3.8 years following tetralogy of Fallot (TF) and ventricular septal defect (VSD) repair. Right bundle branch block (RBBB) and RBBB with left anterior hemiblock (LAH) developed in 88% and 18% respectively, and 22% had transient postoperative complete heart block (CHB). Mean P-A and A-H conduction times were 16.6 and 84.9 msec and were not different from 37 are-matched normal patients and 61 patients with unoperated TF and VSD. The mean H-V conduction time of 48.5 msec was significantly increased compared to the other two groups. Ten postoperative patients had H-V times of 55 msec or greater, indicating trifasicular damage. Of these, five had electrocardiographic bifascicular block (RBBB with LAH) with or without additional 1 degrees A-V block. The remaining five patients' electrocardiograms did not suggest trifascicular damage. Since postsurgical trifascicular damage may progress to late onset CHB, conduction studies are indicated to identify patients at risk, despite surface electrocardiographic findings.

Adolescent↗
PubMed1977

Pre and postoperative ventricular function in infants and children with right ventricular volume overload.

Hemodynamic and ventricular volume parameters were evaluated in 21 patients (24 studies) with total anomalous pulmonary venous return (TAPVR), 11 patients with secundum atrial septal defect (ASD), and eight patients who had complete correction of TAPVR or ASD. Right and left ventricular (RV and LV) volume parameters were calculated according to Simpson's rule and the area length methods, respectively. In infants with TAPVR, RV end-diastolic volume was larger than normal, but RV ejection fraction was significantly less than normal. LV end-diastolic volume and LV ejection fraction were all less than normal in infants with or without pulmonary hypertension, and the values did not correlate with the cardiorespiratory symptoms. In children with TAPVR or ASD, RV end-diastolic volume and output were higher than normal preoperatively and decreased to normal or near normal values postoperatively. The data suggest that pulmonary venous obstruction and/or RV failure are responsible for cardiorespiratory symptoms in infants with TAPVR and early surgical intervention is recommended in these patients.

Blood Volume↗
PubMed1977

Electrocardiographic recognition of sinus node dysfunction in children and young adults.

Twenty-four children and young adults with electrocardiographic evidence of sinus node dysfunction (SND) are described. The patients, whose ages ranged from three days to 25 years, were divided into three groups based on the type of SND. Ten patients had persistent and inappropriate sinus bradycardia (group I): twelve patients had episodes of prolonged sinus arrest (group II); and seven patients had repeated episodes of Mobitz type I or II sinoatrial exit block (group III). Eighteeen patients had significant heart disease and in 11 of these the SND followed corrective cardiac surgery. Seven were operations for atrial septal defect and transposition repair. Seven patients with SND were symptomatic, having either syncopal (3) or near syncopal episodes (4). All three with syncope have received permanent demand pacemakers. These data show that sinotrial exit block occurs in many young patients with SND (29% in this series). Its recognition, however, requires careful electrocardiographic analysis in order to differentiate sinus bradycardia and sinus arrhythmia. Although SND most commonly occurs in children with congenital or acquired heart disease, particularly following corrective cardiac surgery, it may occur in the absence of other cardiac abnormalities.

Adolescent↗
PubMed1976

Sinus node function in children. Factors influencing its evaluation.

Overdrive atrial stimulation was performed in 20 electrophysiologically normal children at the time of routine diagnostic cardiac catheterization, for the determination of the sinus node recovery time (SNRT). Measurements were made at pacing rates of 120, 150, 180, and 200 beats/min. The absolute recovery times demonstrated wide range of values (420-1280 msec). Expressed as a percent of the resting P-P interval, values at pacing rates of 120 and 150 beats/min were 109-166%, with significantly less overdrive suppression (P less than 0.001) occurring at the two faster pacing rates. Atropine diminished the maximum SNRT in all patients tested. This study reports normal values for the SNRT in children. Factors which influence the SNRT are the resting heart rate, the rate of overdrive, and the autonomic tone. In children, the sinus node recovery time should be expressed in terms of the resting sinus interval.

Adolescent↗
PubMed1976

Echocardiographic determination of left atrial volumes in children with congenital heart disease.

The feasibility of determining left atrial volumes (LAV) from LA echo dimensions was assessed in 36 children (group I) with normal cineangiographically determined LAV and 16 children (group II) with LAV overload. Conventional LA echo dimensions, obtained within 24 hours of cardiac catheterization, were compared to the angiographic LA anterior-posterior minor axes (LAmA) and LAV. There was excellent correlation betweeh the LA echo dimensions and the LAmA. In all patients, the LA echo less than LAmA, the differences being more pronounced in group II. Good correlations were found between the LAV and the LA echo, and were expressed by the equations LAV = 7.5 LA echo1.8 (r = .85) and LAV = 8.1 LA echo2.1 (r = .86) for groups I and II, respectively. Changes in LA configuration with volume overload were shown to cause a disproportionate increase in LAmA compared to the other LA dimensions and the LA echo dimension, thus necessitating the separate regression equations. Echo LA to aortic ratios were 0.86 +/- 0.11 and 1.21 +/- 0.23 (mean +/- SD) for groups I and II, respectively. This method of estimating LAV can be useful in the management of left-to-right intracardiac shunts and mitral regurgitation in infants and children.

Adolescent↗
PubMed1976

Postoperative trifascicular block complicating tetralogy of fallot repair.

Transient and residual conduction defects, including early and late complete heart block, are not uncommon in children following the intracardiac repair of tetralogy of Fallot. The case of a young girl is described, in whom early, transient complete heart block was found to be due to trifascicular damage. Through serial electrophysiological studies, gradual improvement in the conducting system was documented, although residual trifascicular damage remained. It is believed that all children with evidence of residual trifascicular damage are subject to possibly fatal bradyarrhythmias due to late postoperative complete heart block.

Bundle-Branch Block↗