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Biomedical subjects

J Liebman

Publications and source records attributed to J Liebman.

At least 55 records · Page 3Linked to original sources
PubMed1983

Surgical therapy for congenital aortic valvular stenosis. A 23 year experience.

This is a review of 70 consecutive patients (2 to 20 years old) who underwent valvotomy for congenital aortic valvular stenosis from 1958 through 1980. A tricuspid valve was created in 36, a bicuspid valve in 33, and a valve prosthesis was inserted in one, with two operative deaths (2.8%). There were four late deaths, three due to noncardiac causes. Eleven patients required reoperation from 2 to 21 years (mean 11.3 years) after valvotomy, with two deaths. Seven patients underwent valve replacement. One patient died 9 years after a second valvotomy. The overall survival rate including reoperation was 92.6% for 10 years and 86% for 15 years. Of 53 surviving patients free of reoperation, 49 are in New York Heart Association Class I and four are in Class II. One of the patients in Class II is a candidate for reoperation. The other 52 patients are well. Twenty-three have normal stress tests, and only one of 24 studied has a pressure gradient greater than 50 mm Hg. We concluded from this experience that valvotomy effectively and safely relieves left ventricular outflow tract (LVOT) obstruction produced by congenital aortic valvular stenosis. It delays the time when a prosthetic device will be required to relieve LVOT obstruction.

Adolescent↗
PubMed1982

The effect of high lung conductivity on electrocardiographic potentials. Results from human subjects undergoing bronchopulmonary lavage.

The effect of increased lung conductivity on ECG potentials was studied in human subjects undergoing pulmonary lavage of a whole lung. In this procedure, the air in the lung is replaced by physiologic saline solution, which is a highly conductive fluid. The same situation was simulated theoretically with an eccentric spherical model of the heart and torso. Both the experimental results and theoretical simulations show a decrease in body-surface potentials as the lung conductivity increases. In particular, a large decrease was observed in the posterior vector and the scalar Z lead both experimentally and theoretically. The model simulation shows that the scalar Z lead is maximal at a conductivity value that is very close to the typical normal lung conductivity, so that low voltages are predicted for low lung conductivities as well.

Cystic Fibrosis↗
PubMed1981

Delayed emergence of antidepressant efficacy following withdrawal in olfactory bulbectomized rats.

Repeated antidepressant treatment attenuates the step-down passive avoidance deficit which is induced by olfactory bulbectomy in rats. Using a shuttlebox passive avoidance procedure, the effects of antidepressants were investigated after various drug withdrawal intervals. Imipramine, amitriptyline, doxepin, bupropion and mianserin were effective at 48 and usually 72 hours after withdrawal, but no significant attenuation of the deficit was seen 4 hours after withdrawal from any antidepressant tested. At least 4 to 7 days of imipramine treatment were required for efficacy. A high dose of d-amphetamine (5 mg/kg) produced similar results while tranylcypromine and haloperidol were inactive at all withdrawal intervals tested. The olfactory bulbectomy syndrome may reflect functional serotonin deficiency, which would be ameliorated through antidepressant-induced alterations in serotonin receptor sensitivity.

Animals↗
PubMed1981

Respiratory variation in Frank vectorcardiography and echocardiography in children.

Forty pediatric patients underwent echocardiographic and Frank vectorcardiographic studies during normal respiration. The right ventricular minor axis (RVEDD) increased significantly with inspiration (p less than 0.005), while the left ventricular minor axis did not significantly change. The distance from the anterior chest wall to the center of the left ventricle did significantly increase with inspiration (p less than 0.005). Some vectorcardiographic parameters changed with inspiration, also. Both the maximal spatial vector to the left (MSVL) and the X to the left (X-L) significantly decreased with inspiration. Although the average magnitude of these changes was small (10-15%), there was wide variation. Five of twenty-one patients with left ventricular hypertrophy during expiration had a clearly normal Frank VCG during inspiration. It is suggested that phases of respiration should be monitored when evaluating the Frank VCG in pediatric patients.

Adolescent↗
PubMed1981

Aromatic L-amino acid decarboxylase in rat corpus striatum: implications for action of L-dopa in parkinsonism.

We studied the distribution of aromatic L-amino acid decarboxylase (AAAD) activity in striatal compartments of rats. After near-total destruction of nigrostriatal dopaminergic neurons, 15 to 20% of the initial enzyme activity remained. Striatal enzyme activity remained unchanged after destruction of serotoninergic terminals by electrolytic raphe lesions. Combined raphe-nigrostriatal lesions or nigrostriatal lesions alone produced similar decreases in striatal decarboxylase. Intrastriatal injection of kainic acid (which selectively destroys striatal interneurons and efferent neurons and also induces marked glial proliferation) reduced activity by 20%. Only 7% of initial striatal activity (perhaps localized in capillaries) remained after combined nigrostriatal-kainic acid lesions. These findings indicate that after degeneration of dopaminergic terminals, striatal interneurons and efferent neurons, but not serotonergic terminals of glia, contain an important fraction of the residual AAAD. This compartment may be the site of enzymatic conversion of exogenous L-dopa to dopamine in the parkinsonian striatum.

Animals↗
PubMed1981

Ventricular interdependence in severe cystic fibrosis. A two-dimensional echocardiographic study.

A variety of mechanisms have been implicated in the development of left ventricular dysfunction in patients with chronic cor pulmonale. A two-dimensional echocardiographic study of cystic fibrosis (CF) patients with severe cor pulmonale was undertaken to evaluate the effects of long-term pulmonary abnormalities on right and left ventricular geometry. Ten patients with severe obstructive pulmonary disease secondary to CF underwent evaluation by a mechanical sector scanner from the long axis, short axis, and four chambered views. All patients manifested right heart failure. Eight had clinical scores less than 40 and died within six months of the initial examination. All patients were receiving diuretics, and six were taking digoxin at the time of the study. The most striking echographic feature was flattening or compression of the left ventricle along its minor dimension by a massively dilated right ventricle. Compression of the left ventricle and additional abnormalities of interventricular septal motion resulted in dyskinetic contraction and relaxation that could contribute to a diminished stroke volume. Massive right ventricular enlargement appears to be a major factor producing left ventricular dysfunction in chronic cor pulmonale.

Adolescent↗
PubMed1980

Heart failure in cystic fibrosis. Treatment and prognosis of cor pulmonale with failure of the right side of the heart.

Failure of the right side of the heart with cardiac dilation and fluid retention occurred in 55 of 170 patients who died of cystic fibrosis; six patients survive. All had severe hypoxia, but 24% had normal PaCO2. Cardiac catheterization showed high mean pulmonary artery pressure and resistance. Pulmonary artery wedge pressure was greater than 12 mm Hg in 40% of the patients. Mean survival was eight months. Male survival was significantly better than female survival. Digitalis treatment was of no clear benefit. Tolazoline hydrochloride was also ineffective. Recent medical advances have not substantially affected prognosis.

Adolescent↗
PubMed1980

Neuroleptic-induced acute dyskinesias in squirrel monkeys: correlation with propensity to cause extrapyramidal side effects.

In squirrel monkeys that had undergone repeated treatment with haloperidol at intervals of 7--14 days, subsequent acute administration of haloperidol induced dystonia and dyskinesias. This acute effect of haloperidol was dose-related and occurred at the same doses that impaired Sidman avoidance performance. Chlorpromazine, fluphenazine, metoclopramide, tetrabenazine, and Su-23397, all of which have been associated with extrapyramidal side effects, reliably elicited dyskinesias in these monkeys. Dyskinesias were less mared after thioridazine and absent after clozapine, corresponding to the reported lower incidence of extrapyramidal side effects in the clinic. The non-neuroleptics, baclofen, and diazepam, failed to elicit dyskinesias. In contrast to the dyskinetic syndrome, the incidence of catalepsy or tremor did not accurately predict propensity to elicit extrapyramidal symptomatology. The acute dyskinetic syndrome in squirrel monkeys may therefore serve as an animal model for predicting the ability of antipsychotics to cause extrapyramidal dysfunction, and may yield insight into the mechanisms of these drug-induced motor disorders.

Animals↗
PubMed1979

Echocardiographic assessment of the adequacy of pulmonary arterial banding.

Thirty-one echocardiograms of 21 patients who had pumonary arterial banding were analyzed to assess the aequacy of surgery. In 5 patients the echocardiograms were obtained before and after banding and in 16 patients only after surgery. Right and left ventricular systolic time intervals were measured echographically. The ratios of the right ventricular preejection period to right ventricular ejection time (RPEP/RVET) were correlated with both diastolic (r = 0.94) and systolic (r = 0.86) pulmonary arterial pressures distal to the band. The analysis of right ventriclar systolic time intervals, especially the RPEP/RVET ratio, clearly differentiated patients with an adequate band (distal pulmonary arterial diastolic pressure less than 15 mm Hg) from patients with an inadequate band (distal pulmonary arterial diastolic pressure equal to or greater than 30 mm Hg). The results indicate that echocardiography is a useful noninvasive tool in evaluating the adequacy of the pulmonary arterial band and facilitates the follow-up of patients after banding.

Blood Pressure↗
PubMed1979

Quantification of the Frank and McFee-Parungao orthogonal electrocardiogram in valvular pulmonic stenosis. Correlations with hemodynamic measurement.

In 66 patients with congenital valvular pulmonic stenosis and intact ventricular septum, correlations were obtined among various multiple hemodynamic and orthogonal vectorcardiographic parameters. The Frank and McFee-parungao lead systems were used. The most important hemodynamic parameter evaluated was right ventricular pressure (RVP). RVP correlated best with X terminal to the right (XTR) in both Frank (R = 0.68) and McFee (R = 0.61) systems. The correlation between RVP and Z anterior was poor. The direction of the initial QRS vector on the X axis was helpful in predicting severity. With X initial to the right, especially in McFee, the RVP is most likely to be systemic or less, while with X initial to the left, the RVP is frequently but not necessarily suprasystemic. T vector spatial orientation is not helpful in the assessment of severity.

Adolescent↗
PubMed1979

Ventricular septal defect in infancy: a combined vectorgraphic and echocardiographic study.

Echocardiograms (echo) and vectorcardiograms (VCG) from 40 infants with ventricular septal defects (VSD) were compared with cardiac catheterization data to assess noninvasively the hemodynamics of VSD. The specific aim was to use VCG parameters of right ventricular hypertrophy and echo parameters which reflect pulmonary artery pressure to identify all patients with a nonrestrictive VSD. The configuration of the QRS vector in the horizontal plane was more reliable than individual voltages in assessing right ventricular systolic pressure. Among patients older than 2 months with a clockwise or anterior two-main-vector horizontal loop, 73% (eight of 11) had a nonrestrictive VSD. However, a counterclockwise or posterior two-main-vector loop was also frequently found (43%, six of 14) in infants with a nonrestrictive VSD. The most useful echo parameter was the ratio of right ventricular preejection period-to-right ventricular ejection time (RPEP/RVET), which closely (r = 0.74) reflected the pulmonary artery diastolic pressure. An elevated RPEP/RVET to greater than 0.30 was always associated with a nonrestrictive VSD, although many patients (36%, five of 14) with a nonrestrictive VSD had a normal ratio. By combining both echo and VCG parameters, a nonrestrictive VSD was correctly identified in all patients, while a restrictive VSD was correctly identified in 81% (21 of 26).

Cardiac Catheterization↗
PubMed1979

Echocardiographic estimation of ventricular hypoplasia in complete atrioventricular canal.

Echocardiograms from 10 patients with complete atrioventricular canal (CAVC) were compared with autopsy specimens to determine the capabilities of echocardiography in identifying patients with ventricular hypoplasia. On the basis of echographic ventricular size, patients could be divided into three groups: 1) "balanced" CAVC patients had both increased right and left ventricular end-diastolic dimensions (RVED and LVED) and an increased RVED/LVED ratio; 2) "dominant left ventricular" CAVC patients had an increased LVED and small or normal RVED and a diminished RVED/LVED ratio; 3) "dominant right ventricular" CAVC patients had an increased RVED, but small LVED, and increased RVED/LVED. There was complete agreement between echographic ventricular dominance and pathologic findings. This study demonstrates that echocardiography may be valuable in assessing ventricular dominance in the presence of CAVC.

Child, Preschool↗
PubMed1979

The effects of variations in conductivity and geometrical parameters on the electrocardiogram, using an eccentric spheres model.

The effects of variations in the volume conductor properties of the torso on the electrocardiogram were studied by means of a theoretical eccentric spheres model. The model includes a blood cavity, cardiac muscle layer, pericardium, lung region, skeletal muscle layer, and subcutaneous fat. The source of the field is a double-layer spherical cap located within the myocardium. The following effects regarding the electrocardiogram (ECG) potentials were determined: (1) blood augments the potential, but less than predicted by simpler published models; (2) in anemia, high potentials are expected, whereas in polycythemia, voltages are reduced; (3) abnormally low lung conductivity (emphysema) causes low surface potentials whose magnitude is controlled by the low conductivity skeletal muscle layer; (4) low voltages result both from low and high pericardial conductivities; (5) the surface potential increases with increasing myocardial conductivity; (6) low skeletal muscle conductivity (Pompe's disease) causes high surface potentials; (7) obesity lowers the potential only slightly; (8) a thick myocardium, protruding into the lung region, slightly augments the potential; (9) an increase in the thickness of the myocardium at the expense of the blood cavity causes a decrease in potential; (10) the potential increases with increasing heart size; and (11) the location of the heart within the torso has a very significant effect on the surface potential distribution.

Action Potentials↗
PubMed1979

Echocardiographic abnormalities in patients with cystic fibrosis.

An echographic study was undertaken to evaluate left (LV) and right ventricular (RV) function in 30 patients with cystic fibrosis. Echographic recording of the pulmonary and aortic valve echogram permitted measurement of the phases of right and left ventricular systole. The ratio of the LV preejection period/LV ejection time (LPEP/LVET) and shortening of the LV internal dimension %SID was employed to reflect LV function, while RV preejection period/RV ejection time (RPEP/RVET) has excellent correlation with pulmonary artery diastolic pressure. RPEP/RVET and two other echographic measurements, right ventricular wall (RVW) and internal dimension (RVD) were compared with pulmonary function tests and clinical scores. RPEP/RVET correlated well with percent vital capacity(%VC), r = -0.73, percent residual volume (%RVol) r = +0.72, and clinical score, r = -0.77. Multilinear regression of RPEP/RVET, RVD, and RVW improved correlation for %VC (r = -0.80), %RVol, r = +0.82, and clinical score, r = -0.84. Patients in overt right heart failure exhibited elevated RPEP/RVET (mean = 0.48) when compared to patients not in right heart failure (mean = .33). Marked diminution of LV function was present in two patients. A variety of cardiovascular abnormalities were demonstrated echographically and were valuable in assessing the degree of cardiac involvement in patients with cystic fibrosis.

Adolescent↗
PubMed1978

Differential behavioral effects of sulpiride in the rat and squirrel monkey.

Despite its clinical efficacy as an antipsychotic agent, sulpiride differs from other neuroleptics in that it has been reported to exert erratic effects in several animal models. The effects of sulpiride were investigated on Sidman avoidance responding by the rat and squirrel monkey. At 100 mg/kg i. p. or orally, sulpiride failed to impair rat Sidman avoidance responding appreciably while exerting marginally toxic effects, but at 30 mg/kg orally, this drug strongly impaired Sidman avoidance responding by the squirrel monkey. This effect, which manifested delayed onset, was reversed by benztropine, indicating that dopamine receptor blockade was most likely responsible for the impairment of responding. The gross behavioral effects of sulpiride in the squirrel monkey resembled those of haloperidol, and dyskinetic postures induced by haloperidol could be mimicked by sulpiride in some instances. It is concluded that the behavioral effects of sulpiride in the rat may not be representative of its action in primates or in the clinic.

Animals↗