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Biomedical subjects

G R Cumming

Publications and source records attributed to G R Cumming.

At least 19 recordsLinked to original sources
PubMed1984

Maximal treadmill tests five years apart in asymptomatic men aged 45-72 years.

169 asymptomatic male volunteers aged 45-72 years not taking part in any fitness or intervention program performed two maximal treadmill tets (Bruce protocol) five years apart. Treadmill endurance time declined 4 to 8 seconds per year; 72% of subjects had changes in endurance time of less than one minute. Maximal heart rate declined about 1 beat/min-1 per year. Horizontal or downsloping ST segment depressions of 0.1 mv or more or slowly upsloping ST depressions of 0.2 mv or more occurred in 26% of subjects at test 1, 38% of subjects at test 2. 25% of subjects with ST abnormality at test 1 were normal at test 2, and 26% of subjects with a normal ST segment at test 1 were classified as abnormal at test 2. Ventricular ectopic beats during or after exercise occurred in 22% of subjects at test 1 and in 37% of subjects at test 2, and the frequency of complex ventricular ectopic activity increased from 2% at test 1 to 9% at test 2. There is a high frequency of exercise induced ventricular extrasystoles, and ST depression in a normal population of older men and it is not known whether there is any need for intervention.

Adult↗
PubMed1982

Cardiac catheterization in infants and children can be an outpatient procedure.

Many cardiac catheterization procedures in infants and children can be performed on an outpatient basis. This has been the practice in a pediatric hospital for 18 years. Over the last 12 years 1,355 of 2,133 catheterization procedures were performed on an outpatient basis. Excluding newborns, 45 percent of infants under 1 year of age having catheterization procedures were studied as outpatients. After age 1 year, 83 percent of the patients were studied as outpatients. Many of the patients admitted to the hospital would have been suitable for outpatient study. There were no significant complications related to the outpatient program. The main advantage would seem to be a reduction in anxiety concerning the test for children and their parents.

Ambulatory Care↗
PubMed1981

Influence of spinal curvature on exercise capacity.

It is well recognized that scoliosis in excess of 65 degrees results in cardiorespiratory impairment. Lesser degrees of spinal curvature have been noted to have near normal respiratory function studies at rest. Because of the great cardiorespiratory reserve, decreases in function secondary to scoliosis may be masked in studies conducted at rest. To study this concept, an investigation of the work capacity of 38 adolescent children with varying degrees of adolescent idiopathic scoliosis was undertaken. The maximal oxygen capacity and endurance time was measured and compared with a group of normal controls. A significant negative correlation between percentile endurance time and degree of spinal curvature was found showing a reduction in endurance time with every 20 degrees increase in spinal curvature (p less than 0.006). The application of "the exercise capacity test" as an investigative tool for scoliosis was found to be practical, since endurance time is a reliable index of the cardio-pulmonary status.

Adolescent↗
PubMed1980

Circulation in neonates with intracranial arteriovenous fistula and cardiac failure.

Two newborn infants with severe cardiac failure caused by a large cerebral arteriovenous communication were studied with complete cardiac catheterization, indicator-dilution curves and angiography. In one infant, studied at age 10 hours, a large right to left shunt through the patent ductus was seen with retrograde aortic flow into the left carotid artery. The entire flow in the descending aorta was supplied from the ductus. The second infant, studied at age 5 days, had a 20 percent right to left shunt through the foramen ovale and the ductus was closed. Hypoxia was caused by inadequate oxygenation of pulmonary venous blood, atrial right to left shunting and possibly ductal right to left shunting. The hemodynamic findings in cases of cerebral arteriovenous fistula would seem to depend on the patient's age at the time the studies are carried out and the severity of the lesion. Cardiac output was more than twice the normal value and blood flow through the arteriovenous fistula was probably greater than 4 liters/min per m2.

Arteriovenous Fistula↗
PubMed1979

Maximal supine exercise haemodynamics after open heart surgery for Fallot's tetralogy.

Maximal supine exercise studies at the time of heart catheterisation were performed one to five years after open heart surgery for Fallot's tetralogy on 29 subjects 6 to 16 years of age. During exercise right ventricular systolic pressure exceeded 50 mmHg in all but 2 subjects, and end-diastolic pressure increased to over 15 mmHg in 10 subjects. Pulmonary artery peak systolic pressure was abnormal in 5 patients. Maximal exercise cardiac index was below the normal range in only 2 subjects, but below the mean for normals in 80 per cent of the patients. Only 3 patients had clinical exercise performances below the 3rd centile of normal subjects using a maximal upright bicycle exercise test, and only 1 subject was below the normal range for endurance time on the Bruce treadmill test. The patients in this series performed better than those in other series, possibly because of their younger age at operation, the use of a large control series of normal subjects taken from a clinic population, the willingness of the patients to work to near exhaustion, and previous encouragement of the patients to become normally active children.

Adolescent↗
PubMed1978

Bruce treadmill test in children: normal values in a clinic population.

The Bruce treadmill protocol is suitable for children as young as age 4 years. Maximal endurance time may be used as the sole criterion of exercise capacity, and normal values were established with 327 children having an innocent heart murmur. Mean endurance time in boys increased from 10.4 minutes at age 4 to 5 years, to 14.1 minutes at age 13 to 15 years. Mean endurance time in girls increased from 9.5 minutes at age 4 to 5 years to 12.3 minutes at age 10 to 12 years. Mean maximal heart rate ranged from 193 to 206 beats/min. Age differences in mean maximal and submaximal heart rates were small. There were negative correlations between endurance time and the ratio of weight to height. There were negative correlations between heart rates at treadmill stages 1 to 3 and the endurance times. The correlation coefficient of endurance time with maximal oxygen uptake was 0.88, but for clinical purposes endurance time alone is a satisfactory indicator of exercise performance.

Adolescent↗
PubMed1978

Maximal exercise capacity of children with heart defects.

Maximal treadmill tests following the Bruce protocol were performed by 830 children with heart defects and the endurance times compared with normal values from 327 children seen in the same clinic because of normal murmurs and from 388 normal children randomly selected and tested in the schools. When values in the normal clinic children were used as the reference, only 21 percent of the patients with heart defects had endurance times below the 10th percentile line. This line was 14 percent higher in the normal school children, and 47 percent of the patient group had values below the 10th percentile when values in the school children were used as the reference. Maximal heart rate in children with heart defects was almost always in the normal range (180 to 210 beats/min) except in patients with cyanosis or severe valve disease and, when encouraged to continue exercising, even these children had a mean maximal heart rate of 175 beats/min. When comparing the exercise capacity of children with heart defects with that of normal children, the source of the normal children is important; body build needs to be considered, as well as physical activity habits. Clinic patients without heart defects probably serve as a better normal control group than children obtained from the school system. Maximal exercise tests do not necessarily distinguish between children with mild or severe heart disease. Only children with lesions causing cyanosis or children with obviously severe disease have consistent reductions in exercise capacity.

Adolescent↗
PubMed1978

Recirculation times in exercising children.

Recirculation times were measured with indicator-dilution methods in 19 subjects, aged 5--14 yr, during near-maximal supine bicycle exercise. Recirculation times were as short as 4.5 s and peak recirculation occurred within 10 s. When rebreathing methods are used to measure exercise cardiac output in children, their very rapid recirculation needs to be considered.

Adolescent↗
PubMed1977

Evaluation of the Canadian Home Fitness Test in middle-aged men.

The Canadian Home Fitness Test (CHFT) and the Bruce treadmill test were performed by 230 men aged 45 to 69 years. Because of inaccuracies in the counting of heart rates, less was known about the fitness of the men after testing than before. In addition, inaccuracies in the test record and design were uncovered. A more accurate estimate of fitness could be obtained when the subjects' own rating of exertional intensity was substituted for heart rate counting. The CHFT is a marketing tool of Health and Welfare Canada that may be useful in selling fitness, but as a measure of fitness in Canadian homes it is likely to be misleading.

Aged↗
PubMed1977

Hemodynamics of supine bicycle exercise in "normal" children.

Sixty children age 5 to 16 years with normal or nearly normal hearts performed submaximal and maximal supine bicycle exercise. Submaximal cardiac output was linearly correlated with work load (r = 0.80). After 2 minutes' exercise cardiac output was over 90 per cent of the value for 6 minutes' exercise. Maximal cardiac index was 10.1 +/- 1.8 for boys and 8.6 +/- 1.8 L. per minute per square meter for girls. Stroke volume was highest during the recovery period after maximal exercise. Pulmonary artery PO2 fell to 24 mm. Hg, oxygen saturation to 33 per cent, and pH to 7.21. During maximal exercise mean pulmonary artery pressure was 24 +/- 5 mm. Hg and mean brachial artery pressure was 113 +/- 8. There were no major differences between children aged 5 to 9 years of age and those 10 to 16 years, except for higher hemoglobin values in postpubertal children.

Adolescent↗
PubMed1976

Constrictive pericarditis with dwarfism in two siblings (mulibrey nanism).

Two siblings with marked dwarfism, now 11 and 19 years of age, have been followed from infancy. The girl had frequent episodes of pneumonitis and presented at age 4 years with hepatic enlargement and ascites which proved to be due to constrictive pericarditis. The boy presented with growth failure and pseudohydrocephalus. He had fibrous dysplasia of the tibia and a pathologic fracture; acute hepatic congestion followed physical activity at age 13 years and led to the diagnosis of constrictive pericarditis. Muscle function was normal, there was no evidence for a primary liver disorder, and mental development was normal so that the coined word "mulibray" seemed inappropriate. Pericardiectomy produced only partial improvement; both patients have hepatic enlargement and continue to need diuretics. A third patient with dwarfism, frequent respiratory infections, and pericardial calcification has certain features of the syndrome.

Adolescent↗
PubMed1976

Second heart sound after pulmonary arterial banding operation.

After a pulmonary arterial banding procedure the phonocardiograms of 38 patients were correlated with haemodynamic and angiographic findings. Twenty-four patients had uncomplicated ventricular septal defect, 2 had single ventricle, 5 had transposition of the great arteries, 5 had atrioventricular canal defects, and 2 had coarctation of the aorta and ventricular septal defect. P2 was separated from A2 by less than 40 ms in 10 of the 11 patients with high pulmonary vascular resistance. Of 27 patients with nearly normal pulmonary vascular resistances and distal pulmonary artery pressures less than 50/20 mmHg (6-7/2-7 kPa), 24 had A2-P2 intervals of over 40 ms. A narrow A2-P2 interval with a satisfactory band was found in 2 patients with large right-to-left shunts. A2-P2 interval did not change appreciably with age, and this measurement is a useful guide as to the effectiveness of pulmonary artery banding by one year after operation. If this interval is less than 40 ms, repeat catheterization should be carried out as such patients may have persisting pulmonary hypertension and an increased pulmonary vascular resistance.

Age Factors↗
PubMed1975

Electrocardiographic changes during exercise in asymptomatic men: 3-year follow-up.

Electrocardiographic (ECG) changes during maximal bicycle exercise and risk factors for coronary heart disease (CHD) were studied in 510 male civic employees who were followed for 3 years. Clinical CHD developed in 15 (24.6 percent) of the 61 men with an ischemic exercise ECG on the initial examination and in 11 (2.4 percent) of the 449 subjects with a normal initial exercise ECG. A normal maximal exercise ECG is no guarantee that severe CHD does not exist and that a subject will not soon sustain major myocardial damage; and an ischemic exercise ECG does not necessarily indicate underlying CHD. In the former group angina was the most frequent clinical CHD episode; in the latter group, infarction. Among those with an abnormal initial exercise ECG, CHD was most likely to develop in association with a poor exercise capacity. Subjects with subsequent clinical CHD and those with abnormal ECGs after 3 years tended to have a higher frequency of risk factors; subjects whose abnormal ECGs reverted to normal after 3 years tended to have a lower frequency of risk factors.

Adult↗