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Biomedical subjects

J G Shakibi

Publications and source records attributed to J G Shakibi.

At least 37 records · Page 2Linked to original sources
PubMed1979

Electrophysiologic effects of verapamil in children.

The electrophysiologic effects of verapamil, a slow channel blocker, were investigated during diagnostic cardiac catheterization in 24 children premedicated with lytic cocktail. The ages ranged from 50 days to 12 years. Twenty had congenital and 4 had rheumatic heart disease. Surface EKG, high intra-atrial and His bundle electrograms were obtained in all before and 5 min after a single dose of verapamil (0.15 mg/Kg, max 5 mg iv). In 14 cases complete electropysiologic studies were performed using the atrial pacing and extrastimulus technique. Due to variability of the resting heart rates and the effect of cycle length on refractory periods each paced with identical S1-S1 interval before and after verapamil, thus allowing each case to serve as his own control. Verapamil prolonged the corrected AH interval in all (mean +/- SD; from 116 +/- 37 to 152 +/- 41 msec, p less than 0.01) and shortened the HV interval in 15/24 (mean +/- SD: from 55 +/- 13 to 47 +/- 9.9 msec, p less than 0.05). The effective and functional refractory periods of the total conduction system, the AV node (ERPAVN) and atrium (ERPA) increased significantly in 10/14. The most profound effect was on ERPAVN and ERPA (25.54 +/- 29 and 19.27 +/- 21.81 percent mean percent increase +/- SD respectively, p less than 0.01 and p less than 0.02). Our findings show that verapamil prolongs the effective and functional refractory periods of the cardiac conduction system with maximal effects on the AV node, thus suggesting the mechanism of its effectiveness in the treatment of reentrant supraventricular arrhythmias.

Adolescent↗
PubMed1978

Quantitative angiocardiographic recognition of atypical form of tetralogy of Fallot with absent pulmonic valve.

A 9-year-old boy is reported who had tetralogy of Fallot, rudimentary pulmonic valve, and supravalvar pulmonic stenosis. The patient lacked almost all of the clinical findings commonly encountered in this syndrome. Thus he never had signs of a large left-to-right shunt, or congestive heart failure. He had no murmur of pulmonic regurgitation and his pulmonary artery was not large on chest roentgenogram. Angiocardiography revealed moderate main pulmonary arterial dilation. The lack of the usual manifestations of tetralogy of Fallot with absent pulmonic valve was due to supravalvar pulmonic stenosis, acting as a natural pulmonary artery band. A quantitative angiocardiographic study was undertaken in order to find a clue for the diagnosis of these atypical cases. The ratio of the transverse diameters of the main pulmonary artery and the aortic root as measured on lateral angiocardiograms in 31 children with uncomplicated tetralogy of Fallot was 0.70 +/- 0.22, whereas this ratio was 1.70 in this particular patient (p less than 0.001). It is concluded that a quantitative evaluation of the ratio of the transverse diameter of the main pulmonary artery to the aortic root on lateral angiocardiogram allows differentiation of tetralogy of Fallot with absent pulmonic valve associated with supravalvular pulmonic stenosis from uncomplicated forms of tetralogy of Fallot.

Angiocardiography↗
PubMed1978

Association of atrioventricular valve atresia with single ventricle, truncus arteriosus communis and transposition. A basic reorientation in the approach to the definition of congenital heart defects.

A heart specimen is presented which showed a rare combination of atrioventricular valve atresia with single ventricle, truncus arteriosus communis with an anteriorly placed trunk, ie transposition. Because of the problems involved in the classification of this heart, the types of single ventricle are revised with particular attention to the rare cases of atrioventricular valve atresia and single ventricle reported in the literature. Also the rare type of truncus arteriosus communis with truncoatrioventricular valve discontinuity is excluded from the so-called transposition complexes, and properly classified as a form of truncus. The literal meaning of transposition is stressed and it is urged to approach congenital heart defects in a purely anatomic sense with definition of each segment as accurately as possible. Thus the present confusion in terminology and further plethora of new terms are avoided.

Child↗
PubMed1978

Isolated unilateral absence of the pulmonary artery. Review of the world literature and guidelines for surgical repair.

A 10-month-old boy is presented who had isolated unilateral absence of the right pulmonary artery. He suffered from hemoptysis and severe congestive heart failure. The patient underwent prosthetic anastomosis of the right to the main pulmonary artery. Although the hemodynamic response was favorable, his oxygenation did not improve due to diffuse pulmonary arteriovenous fistulae of the affected lung. The patient succumbed 3 months after operation due to massive uncontrollable hemoptysis from the right lung. Isolated unilateral absence of the pulmonary artery is a rare lesion. In our review of the world literature as of November 1976, 47 cases (including this report) of the unilateral absence of the pulmonary artery have been reported. Of these 25.5% had pulmonary hypertension and only 4 cases underwent successful repair of the lesion. Though repair of this defect can be carried out, the result may not be always gratifying. Our experience with this case has led us to consider a lung biopsy before proceeding to the surgical repair of the lesion. If the affected lung shows arteriovenous abnormalities the operation should not be recommended.

Blood Vessel Prosthesis↗
PubMed1978

Cardiovascular emergencies in pediatrics.

This article dicusses emergencies of cardiovascular origin in infants and children. Particular attention is given to congestive heart failure, hypoxic states, arrhythmias, cardiac tamponade, perinatal cardaic emergencies and conditions simulating cardiac crises. An outline of etiologic and therapeutic approach is included, and guidelines are provided for the practitioner who is called to care for such emergency situations.

Arrhythmias, Cardiac↗
PubMed1977

The vectorcardiogram as an aid to diagnosis in left ventricular-right atrial communication.

Frank vectorcardiograms (VCGs) in four patients with left ventricular-right atrial (LV-RA) communication were analyzed and compared with published values of VCGs of normal individuals and those from a group of patients with membranous ventricular septal defect. It was observed that the QRS-loops in the frontal and sagittal planes of the patients with LV-RA communication are shifted more superiorly than usual. Thus, almost 50% of the QRS-loop area was superior to the X- and Z-coordinates in the frontal and sagittal planes, whereas in the controls less than 10% of the frontal and sagittal plane QRS-loops were superior to the horizontal axes. The QRS-loops of patients with LV-RA communication thus seem to be halfway between normal and endocardial cushion defect loops. An unusual degree of superior orientation of the QRS-loop in a patient with clinical findings of a ventricular septal defect should arouse suspicion of a LV-RA communication. Also in patients with an isolated ventricular septal defect but with an exaggerated superior orientation of the QRS-loop in the frontal and sagittal planes, the interatrial septum should be examined at the time of operation to exclude the possibility of an associated LV-RA communication.

Child↗
PubMed1977

Regression of pulmonary hypertension after mitral valve surgery in children. Operative management of rheumatic mitral valve disease.

Forty-one children with advanced chronic rheumatic disease of the mitral valve had preoperative and postoperative hemodynamic studies. Twenty-three cases had open mitral commissurotomy, and 20 had mitral valvular replacement. After surgery the average pulmonary arterial systolic pressure in the group with valve replacement decreased from 78 to 42 mm Hg, the pulmonary vascular resistance decreased from 974 to 313 dynes sec cm 5, and the cardiac index rose from 2.29 to 4.15 L/min sq m. In the group with mitral commissurotomy, the average pulmonary arterial systolic pressure decreased from 90 to 63 mm Hg, the pulmonary vascular resistance decreased from 1,201 to 616 dynes sec cm-5, and the cardiac index rose from 2.5 to 3.5 L/min sq m. While all patients with mitral valve replacement showed a drop in pulmonary arterial pressure, the postoperative pressures were higher after commissurotomy in four patients, two of whom required a second operation of valve replacement. The study shows that in children, even severe degrees of pulmonary hypertension secondary to mitral valve abnormality is corrected.

Adolescent↗
PubMed1977

A morphometric study of the aortomitral valve apparatus in the embryonic and adult chicken heart. Implications on the developmental hypotheses of the transposition of the great arteries.

A comparative morphometric study was performed on the aortomitral valve apparatus of the embryonic and adult chicken hearts. It was found that the thickness of the aortic and mitral valve cusps diminishes dramatically as the embryo matures, however the relative length of the aortic valve, mitral valve and subaortic conus remains constant. A comparison of the aortomitral valve apparatus in chicken and man revealed that the subaortic conus is not completely resorbed in the fowl, whereas this process is well documented in the mammalian hearts. The implications of this observation on "the differential conal growth hypothesis" of transposition of the great arteries are discussed.

Animals↗
PubMed1977

Surgical treatment of echinococcal cyst of the heart. Report of two cases and review of the world literature.

The case histories of two children with echinococcal cysts of the left ventricular myocardium are reported. Both patients underwent successful enucleation of the cysts, after initial local treatment with 0.5 percent silver nitrate solution. A previous review of the world literature on the surgical treatment of echinococcal cyst of the heart, published in 1971, is brought up to date by the addition of 60 new cases to the 118 cases then described. Instillation of 0.5 percent silver nitrate solution into the cyst cavity is now a routine procedure in our institution to sterilize the cyst and to kill the scolices. This substance is preferable to formalin and hypertonic sodium chloride solution, because it acts rapidly and is nontoxic and nonabsorbable. The two children in this report are the first in whom silver nitrate solution was used to sterilize the myocardial cysts.

Adolescent↗
PubMed1976

Prediction of pulmonary arterial pressures from electrovectorcardiographic data in pediatric patients with rheumatic mitral valve disease.

The Frank vectorcardiogram (VCG) and the electrocardiogram (ECG) were used to predict pulmonary arterial pressures in 30 pediatric patients with rheumatic mitral valve disease. The patients' ages ranged from eight to 14 1/2 years. Eleven were male and 19 were female. Sixteen had mitral stenosis, eight had mitral regurgitation and six had mitral stenosis and regurgitation. Mean pulmonary arterial wedge pressure ranged from 5-32 mmHg. All patients underwent complete catheterization and angiocardiographic study. None had significant gradient across the right ventricular outflow tract. Right maximum spatial vector (Rmsv) was calculated using Frank VCG.R in V1 and S in V5 of ECG were also measured. Rmsv, RV1, and SV5 were correlated with pulmonary arterial pressures (systolic, diastolic and mean). Pulmonary artery systolic pressure and Rmsv bear the best correlation (r=0.773). The correlation coefficient for pulmonary artery diastolic pressure and Rmsv was 0.698. Rmsv as calculated from Frank VCG is useful in prediction of pulmonary arterial pressures (systolic and diastolic) in pediatric patients with rheumatic mitral valve disease.

Adolescent↗
PubMed1976

Antiarrhythmic effect of hypertonic sodium bicarbonate and sodium chloride in ouabain-induced arrhythmias.

Ouabain-induced tachyarrhythmias in cats can be abolished by bolus injection of NaHCO3 solution. This effect is consistent, rapid and of short duration. The antiarrhythmic effect appears to be due to high sodium concentration of this solution, as hypertonic NaCl solution with equal concentration of sodium exerts the same effect. Alkalinity and hyper-osmolality cannot account for the antiarrhythmic effect of NaHCO3 as respiratory alkalosis and mannitol solution with equal osmolality did not relieve the arrhythmias. Overdrive suppression is not responsible for this effect as the heart rate slows down during normalization of the cardiac rhythm. It is postulated that high Na+ concentration abolished ouabain-induced arrhythmias by competition with calcium ion in the myocardial cell sarcotubular system thus replacing it. This hypothesis is supported by the known effect of other agents such as sodium-EDTA and magnesium chloride, in digitalis-induced arrhythmias, which exert their antiarrhythmic properties by removal or displacement of calcium in the myocardial cells.

Animals↗
PubMed1976

Simplified vectorcardiographic method for assessment of pulmonary arterial pressure in children with chronic rheumatic mitral valve disease.

We previously reported that pulmonary artery pressures can be assessed in children with chronic rheumatic mitral valve disease by measuring right maximum spatial vector from Frank vectorcardiogram. To simplify the calculation, pulmonary artery systolic pressure was correlated with maximum negative deflection on Frank scalar X-lead (SX), maximum negative deflection on scalar Z lead (SZ), sum total of SX and SZ (SX+SZ) and combined SX and SZ. The patient material consisted of 30 children with chronic rheumatic mitral valve disease, aged 8-14 1/2 years. Eleven were male and 19 were female. Sixteen had mitral stenosis, 8 had mitral regurgitation, and 6 had combined mitral regurgitation and stenosis, documented by cardiac catheterization and angiocardiographic study. The results showed a significant correlation between pulmonary artery systolic pressure and SX (r=0.782). As calculation of SX is considerably easier and less time consuming than that of right maximum spatial vector, this simplified method is preferable to right maximum spatial vector for prediction of the pulmonary artery systolic pressure of children with pulmonary hypertension due to chronic rheumatic mitral valve disease.

Adolescent↗