Clean Air and Noise Abatement Branch, Public Health Department, Western Australia

Whole blood lead levels, free erythrocyte protoporphyrin (FEP) concentrations, and hair lead levels were measured in 181 schoolchildren resident in and around the town of Northampton, Western Australia, where tailings from a lead mine have been used extensively for ground surfacing and other purposes. Mean blood lead levels were 0.68 mumol/L (14.0 micrograms/100 mL) in boys and 0.5 mumol/L (10.4 micrograms/100 mL) in girls, the highest being 2.27 mumol/L (47 micrograms/100 mL). Nine children (5%) had blood lead levels above 1.21 mumol/L (25 micrograms/100 mL) and four had levels above 1.21 mumol/L (25 micrograms/100 mL) and four had levels above 1.45 mumol/L (30 micrograms/100 mL). Four of these children had FEP levels above 2.0 mumol/L. There was a statistically significant difference between the mean blood lead levels of children resident in the town (man blood lead level, 0.63 mumol/L (13.1 micrograms/100 mL)) compared with those resident out of the town 0.55 mumol/L (11.3 micrograms/100 mL). The presence of lead tailings in the town may account for the small difference.

Ventricular tachycardia in children

Thirty-eight patients aged 1 to 20 years (mean 11.2) were evaluated because of recurrent ventricular tachycardia. The follow-up period ranged from 0.5 to 12 years (mean 6). The patients were separated into two groups according to the presence or absence of known structural heart disease. Seventeen of the 21 patients with known heart disease were symptomatic (cardiac arrest in 5, syncope in 5, dizziness in 7) compared with only 6 of the 17 patients without heart disease (syncope in 3 and dizziness in 3) (p less than 0.01). All symptomatic patients had ventricular tachycardia with rates of more than 150 beats/min, whereas all but one of the asymptomatic patients had rates of less than 150 beats/min (p less than 0.01). Graded treadmill exercise testing was performed in 21 of the 38 patients. Exercise increased the degree of ventricular arrhythmia in 8 of the 11 symptomatic patients but decreased or abolished the arrhythmia in 9 of the 10 asymptomatic patients (p less than 0.01). Antiarrhythmic therapy was used in 28 of the 38 patients. Effectiveness of therapy was assessed with both 24 hour Holter monitoring and graded treadmill exercise testing. Therapy effectively abolished ventricular tachycardia and greatly decreased the number of premature ventricular complexes in the symptomatic patients but was less effective in the asymptomatic patients. Thus, this study suggests that the presence of underlying heart disease, the rate of ventricular tachycardia and the results of graded treadmill exercise tests are important in predicting the prognosis of children with ventricular tachycardia.

Electrophysiologic delineation of the intraventricular His bundle in two patients with endocardial cushion type of ventricular septal defect

Two patients who had an endocardial cushion type of ventricular septal defect underwent electrophysiologic studies for detection of specialized conduction tissue during operative repair. In one patient, with an inferior leftward frontal plane QRS axis on the ECG, we recorded an intraventricular His bundle electrograms from both the anterosuperior and posteroinferior margins of the defect, suggesting dual atrioventricular conduction tracts (branching intraventricular His bundle). These anatomic and electrophysiologic findings may account for the more normally oriented QRS frontal plane axis on the surface ECG of both of these patients and support the hypothesis that the changes observed on the ECGs of patients with the various forms of endocardial cushion defect can be explained by alterations in the anatomic configuration of the specialized atrioventricular conduction tissue.

Distribution and inheritance of low serum thyroxine-binding globulin levels in Australian Aborigines: a new genetic variation

Evidence is presented that low serum thyroxine-binding globulin (TBG) levels in Aborigines are widely distributed throughout Australia, and that these are inherited rather than acquired. Levels of TBG in children, and lack of any correlation of low TBG levels with alcohol consumption or liver dysfunction, suggest that the low levels are not acquired in adult life. Genetic studies in eight families indicate (with one exception) an autosomal dominant pattern of inheritance with direct male-to-male transmission. These findings are in marked contrast to the much rarer X-linked pattern of inheritance of low TBG levels in Caucasians. This type of prevalent and inherited low level of TBG in serum appears so far to be unique to the Aboriginal race. The synthesis (or degradation) of TBG may be controlled by an autosomal gene in Aborigines.

Prevalent low serum thyroxine-binding globulin level in Western Australian aborigines: its effect on thyroid function tests

The first major variation from the normal human levels of thyroxine-binding globulin (TBG) in a racial group is reported in full-blood Aborigines of Western Australia. This finding has not only biochemical and anthropological interest, but also medical significance in that many common laboratory tests of thyroid function in this group are very liable to misinterpretation because of low TBG levels. In Aborigines in the Halls Creek area of Western Australia, 40% have TBG levels below the lower reference limit for Caucasians, and 18% have levels between half and one-third of the lower limit. Such subjects have low thyroxine levels by Caucasian standards, and frequently the results of triiodothyronine uptake (T3U) tests lend support to the false suggestion of hypothyroidism. Caucasian reference ranges are not valid in this large proportion of the Aboriginal population. It is not yet clear whether the low TBG levels are a normal feature in this racial population, or whether there is some other cause. The subjects of the study were not acutely ill and Aborigines with low TBG are well distributed throughout the State.

Intraoperative recording of specialized atrioventricular conduction tissue electrograms in 47 patients

Intraoperative mapping of the specialized atrioventricular conduction system was performed in 47 patients during cardiac surgery. Specialized conduction tissue electrograms were identified in 37, and atrioventricular conduction preserved in 92%. Specialized conduction tissue was identified in 27 patients with atrioventricular canal defect: complete heart block was avoided in 25. Conduction tissue was located in six of 12 patients with complex transpositions; atrioventricular conduction was preserved in all six. Other lesions in which the technique was useful were Ebstein's anomaly and single atrium. Limitations to the technique are 1) deep hypothermia and circulatory arrest; 2) interruption in atrioventricular conduction during mapping; 3) inadequate exposure and access to probable sites of conduction tissue; 4) variation of size and spatial relations of individual malformations; and 5) limited time for identification of unusually located conduction tissue. Indications for use of this technique include patients with both forms of atrioventricular canal, complex transpositions, atrioventricular discordance, single ventricle and single atrium.

Early and late results with the Mustard operation in infancy

Eighty-one patients, ranging in age from 36 hours to 24 months and in weight from 2.5 to 12 kg had a Mustard operation for D-transposition of the great arteries (D-TGA) (20 with complex D-TGA) using either deep hypothermic circulatory arrest (68 patients) or conventional cardiopulmonary bypass (13 patients). A Dacron patch was used for the intraatrial baffle and pericardium for augmentation of the pulmonary atrium. Ten patients died following operation. Thirty-two patients had cardiac catheterization 1 year after operation. Of 24 patients with D-TGA and intact ventricular septum, 23 had normal pulmonary artery pressures. In 20 patients left ventricular outflow tract gradients decreased from a mean of 32 mm Hg to a mean of 18 mm Hg after operation. Five patients who had D-TGA and ventricular septal defect and systemic pressures in the left ventricle before operation, had a notable decrease in left ventricular pressures after the procedure. Seven patients required reoperation for baffle obstruction. Mortality following Mustard repair was primarily related to the complexity of the lesion, maturity of the infant, and degree of pulmonary vascular changes. Caval obstruction was related to the configuration of the baffle used in the early part of this series.

His bundle electrogram after intracardiac repair of tetralogy of Fallot. Analysis of data in 59 patients

His bundle electrograms were recorded in 59 patients after intracardiac repair of tetralogy of Fallot and were correlated with the postoperative electrocardiogram. Except for five patients with first degree atrioventricular block postoperatively all patients in Group A (those with either a normal electrocardiogram or solitary right bundle branch block) had a normal A-H interval (77.7 +/- 21.6 msec) (mean +/- standard deviation); all had a normal H-V interval (39.5 +/- 7.2 msec). Patients in Group B (bifascicular block) tended to have a normal A-H interval (97.2 +/- 26.2 msec) with a prolonged H-V interval (48.8 +/- 10.7 msec). Patients in Group C (trifascicular block) had prolongation of both the A-H (160.0 +/- 32.4 msec) and the H-V interval (58.8 +/- 10.6 msec) by comparison with control values. Patients in Group D (transient complete heart block) had a normal A-H interval (79.5 +/- 28.2 msec) but a prolonged H-V interval (57.8 +/- 16.4 msec), similar to that in Group C. A good hemodynamic result was associated with a normal H-V interval; a prolonged interval accompanied a poor result.

An improved screening method for 3-methoxy-4-hydroxy mandelic acid excretion in urine

A screening method is described for urinary 3-methoxy-4-hydroxy mandelic acid using an initial ion exchange procedure, vanillin formation and extraction into toluene. The technique, is simple, rapid and specific, with a reference value up to 35 mumol (7.0 mg)/day established on 92 normal human subjects. Over 200 patients' urines were analysed by the method of which 18 gave values above the reference range. The majority of these increased excretions are attributed to the metabolic effects of drugs, one patient suffered from phaeochromocytoma and only 2 results remaining unexplained.

Electrophysiologic delineation of the specialized atrioventricular conduction system in two patients with corrected transposition of the great arteries in situs inversus (I,D,D)

Electrophysiologic delineation of the atrioventricular conduction system at surgery is described in two patients with corrected transpostion of the great arteries in situs inversus. Intra-atrial electrograms were recorded in one patient from sites immediately adjacent to the coronary sinus located in the left-sided right atrium. The intraventricular portion of the atrioventricular conduction system was identified in both patients along the posterior and inferior margin of the ventricular septal defect, in contrast to the superior and anterior location found in corrected transposition of the great arteries in situs solitus. In contrast to the superior and anterior location found in corrected transposition of the great arteries in situs solitus. The course of the conduction system in the hearts of these two patients and a possible relationship to the cardiac loop and dual origin of the atrioventricular node is discussed. These cases illustrate the usefulness of segmental diagnosis of congenital heart disease and of electrophysiologic identification of the specialized atrioventricular conduction system at surgery.

The palliative Mustard operation for double outlet right ventricle or transposition of the great arteries associated with ventricular septal defect, pulmonary arterial hypertension, and pulmonary vascular obstructive disease. A report of eight patients

Five patients with double outlet right ventricle, ventricular septal defect, pulmonary arterial hypertension and pulmonary vascular obstructive disease and three patients with complete d-transposition of the great arteries, ventricular septal defect, pulonary arterial hypertension and pulmonary vascular obstructive disease underwent an elective Mustard baffle operation. The ventricular septal defect was not closed. A large patent ductus arteriosus was divided in three patients. Seven of the eight patients are alive five to 32 months after surgery; one patient died 11 months after surgery. Cyanosis, dyspnea on exertion, and exercise limitation improved initially in all and has persisted in the survivors. In pre and postoperative hemodynamic studies in four patients, systemic arterial oxygen saturation and effective pulmonary blood flow increased from mean values of 70% to 90% and 1.7/min/m2 to 3.3 L/mon/m2, respectively. Absolute systemic and pulmonary flows, and pressures and resistances, were not significantly altered. Criteria for selection of patients with transposition of the great arteries of double outlet right ventricle who would benefit from a palliative Mustard procedure (Mustard atrial baffle without closure of the ventricular spetal defect) are: 1) severe symptoms; 2) pulmonary arteiral hypertension (75% systemic) with pulmonary vascular obstructive disease; and 3) pulmonary artieral oxygen saturation greater than systemic (ascending aorta) arterial oxygen saturation by approximately 10%.

Interrupted aortic arch in infancy

Data from 30 infants with interrupted aortic arch in the New England Regional Infant Cardiac Program, 1968 to 1974, were reviewed. All patients had major associated cardiac abnormalities: approximately one third had ventricular septal defect with patent ductus arteriosus, one third had complex ventricular septal defect with left ventricular outflow obstruction, and one third had complex intracardiac lesions incompatible with survival. Twenty-one of the patients had either palliative or reconstructive surgery, with a hospital mortality rate of 76%. Nine patients did not have surgery; eight of them died at a median age of four days. One-stage primary repair of interrupted aortic arch including the associated cardiac defects, using deep hypothermia and circulatory arrest, is proposed as the current method of treatment in such infants.

Intraoperative recording of the His bundle electrogram in man. An assessment of its precision

To estimate the effect of distance between the electrode and the signal source on the amplitude of the His bundle electrogram (HBE) recorded during open heart surgery, a specially designed probe, containing six pairs of closely spaced (1 mm) electrodes was placed on the endocardial surface of the right atrium such that each electrode pair was parallel to the course of the His bundle. The amplitude of the HBE recorded through electrodes closest to the His bundle ranged from 0.76 to 2.44 mV, at 1mm from 0.38 to 1.13 mV, at 2mm from 0.27 to 0.86 mV, and at 3 mm from 0.2 to 0.44 mV. Maximal amplitude of HBE decreased by 57% at 1mm, 73% at 2 mm, and 82% at 3mm. The percent decrease was initially rapid, then declined more slowly at distances greater than 1 mm, resembling in form data obtained previously in animal studies by different techniques. Since the maximum HBE was greater than 1.0 mV in nine of 11 patients, and equal to or greater than 1.0 mV in only two of 11 patients at 1 mm, and less than 1.0 mV in all patients 2.0 mm from the maximal HBE, the anatomic location of the His bundle can be estimated from HBE amplitude. Intracardiac electrograms, recorded through closely spaced bipolar electrodes during open heart surgery, afford clinically useful precision in locating the specialized conduction tissue of the heart.

Left ventricular function in tricuspid atresia. Angiographic analysis in 28 patients

Thirty-one left ventricular (LV) biplane angiograms were performed in 28 patients with tricuspid atresia. Measurements of left ventricular end-diastolic volume (LVEDV) and left ventricular end-systolic volume were obtained by the modified Simpson's rule and systolic ejection fraction (EF) calculated. Left ventricular volumes and ejection fractions were also obtained in 19 control patients with no significant heart disease. The patients with tricuspid atresia were classified according to the appearance of the pulmonary vascularity on initial radiologic examination: Group A, decreased pulmonary vascularity; Group B, increased pulmonary vascularity. In the 13 group A infants who were unoperated, LVEDV was increased and EF mildly diminished. In the group B patients LVEDV was increased and EF normal. In the 12 group A patients with surgical shunts LVEDV was elevated. The five group A patients with long-standing systemic artery to pulmonary artery anastomoses (greater than 10 years) showed the largest LVEDV and the poorest EF. The angiographic data indicate that patients with tricuspid atresia experience significant LV dysfunction as a consequence of longstanding LV volume overload. The early detection of LV dysfunction may be an indication for a right ventricular bypass procedure in these patients.

Repair of tetralogy of Fallot after catheterization-induced complete heart block

The case of a four-year-old boy with tetralogy of Fallot who developed complete heart block during cardiac catheterization and subsequently underwent surgical repair in the presence of heart block is presented. Return to normal sinus rhythm occurred on the 11th postoperative day, and the manner in which increased atrioventricular conduction appeared was documented with the use of a continuous Holter monitor. Placement of a temporary transvenous pacemaker, systemic heparinization in the preoperative period, and the insertion of a permanent epicardial wire during surgery were performed.

Tricuspid atresia: clinical course in 101 patients

The clinical profile and course of 101 patients with tricuspid atresia seen at the Children's Hospital Medical Center, Boston, were reviewed; the electrocardiograms, hemodynamic data, associated anomalies, complications of the malformation and surgical results were outlined and a definition of anatomic types and radiologic groups formed in order to facilitate therapeutic decisions. Overall survival to 15 years of age was approximately 50 percent. Tricuspid atresia type 1 (normally related great arteries), group A (decreased pulmonary vascularity) was the most frequent category (54 percent); without surgery, these patients had only a 10 percent chance of survival beyond the 1st year of life. Surgical intervention improved chance of survival to 15 years of age to 50 percent. Overall surgical mortality was 23 percent. The Waterston shunt is the procedure of choice in symptomatic small infants with diminished pulmonary flow (group A). Type II patients with increased pulmonary blood flow (group B) would benefit from a pulmonary arterial band. In contrast, patients with group B, type I atresia would rarely need a pulmonary arterial band. Patients with spontaneously changing hemodynamics (group C) usually require a shunt later in life than those in group A, with more favorable operative results. Our experience indicates the continued need of early surgical palliation. New surgical approaches, such as the right atrial-pulmonary arterial anastomosis, may result in a more prolonged survival.