- Email: [email protected]
A new symbol for the equilateral tetrahedral reference frame
Annotations
A new
symbol
reference
for
the equilateral
frame
Those writing about spatial vectorcardiography encounter difficulty with the need to write terms repeatedly, many of them being long. The field is new and, of course, still unsettled. With experience and time, improvements will develop, including simplifications. The symbol v has been employed in electrocardiography to indicate the “equilateral triangle of Einthoven.” This symbol certainly simplifies discussions of Einthoven’s triangle a great deal.
Total
body
prolonged
tetrahedral
potassium diuretic
We suggest that a dot ‘be placed within this same sy.mbol located just, above the center thus, v, to represent the “equilateral tetrahedron.”
Tulane
changes
G. E. Burch, M.D. Department of Medicine University School of Medicine 1430 Tulane Ave. New Orleans, La. 70112
with
therapy
A normal healthy man of 70 kilograms body weight has a potassium content of about 140 Gm. (3,500 mEq.), most of the potassium being intracellular with less than 3 per cent in the extracellular fluid. Continuous treatment with diuretics may produce a considerable fall in the plasma potassium concentration, but since so much of body potassium is intracellular there is a question as to whether this change is accompanied by potassium depletion. Measurements of exchangeable potassium using potassium-42 and a dilution method have usually,‘-3 though not invariably,’ shown some reduction of body potassium. Such studies are, however, much limited by the undesirability of repeatedly administering radioactive substances so that usually one or two measurements are all that is possible. The use of highly sensitive whole body counters to measure the body’s content of the naturally-occurring radioisotope, potassium-40, obviates the difficulty as a radioisotope does not have to be given and so repeated estimations can be made. Potassium-40 emits y radiations and occurs naturally in constant proportion (0.0118 per cent) to stable potassium so that by determining the amount of potassium-40 present, the potassium content can be immediately
calculated. The amount of potassium-40 in a normal man is only a few thousandths of a microcurie and so rather elaborate apparatus is needed to measure it accurately. Since radionuclides do not have to be given and the procedure is completed in about twenty minutes, potassium-40 counting is potentially of considerable clinical value, though unfortunately the expensive equipment needed at present precludes its extensive use except as a research tool. As part of a research project, we have been making periodic measurements of total body potassium over several years in a group of normal individuals and in patients on treatment with diuretics, most of the latter being hypertensive patients 1,who were taking diuretics (usually a thiazide drug) as part of their hypotensive regime. A convenient way of expressing the results is to state the observed value of total body potassium (K& at any time as a proportion of the untreated or expected value for the individual (Kexp), the latter being usually obtained from measurements made before the individual commences treatment. With normal untreated individuals on a normal diet, we have observed only small fluctuations in total 569
A new
symbol
reference
for
the equilateral
frame
Those writing about spatial vectorcardiography encounter difficulty with the need to write terms repeatedly, many of them being long. The field is new and, of course, still unsettled. With experience and time, improvements will develop, including simplifications. The symbol v has been employed in electrocardiography to indicate the “equilateral triangle of Einthoven.” This symbol certainly simplifies discussions of Einthoven’s triangle a great deal.
Total
body
prolonged
tetrahedral
potassium diuretic
We suggest that a dot ‘be placed within this same sy.mbol located just, above the center thus, v, to represent the “equilateral tetrahedron.”
Tulane
changes
G. E. Burch, M.D. Department of Medicine University School of Medicine 1430 Tulane Ave. New Orleans, La. 70112
with
therapy
A normal healthy man of 70 kilograms body weight has a potassium content of about 140 Gm. (3,500 mEq.), most of the potassium being intracellular with less than 3 per cent in the extracellular fluid. Continuous treatment with diuretics may produce a considerable fall in the plasma potassium concentration, but since so much of body potassium is intracellular there is a question as to whether this change is accompanied by potassium depletion. Measurements of exchangeable potassium using potassium-42 and a dilution method have usually,‘-3 though not invariably,’ shown some reduction of body potassium. Such studies are, however, much limited by the undesirability of repeatedly administering radioactive substances so that usually one or two measurements are all that is possible. The use of highly sensitive whole body counters to measure the body’s content of the naturally-occurring radioisotope, potassium-40, obviates the difficulty as a radioisotope does not have to be given and so repeated estimations can be made. Potassium-40 emits y radiations and occurs naturally in constant proportion (0.0118 per cent) to stable potassium so that by determining the amount of potassium-40 present, the potassium content can be immediately
calculated. The amount of potassium-40 in a normal man is only a few thousandths of a microcurie and so rather elaborate apparatus is needed to measure it accurately. Since radionuclides do not have to be given and the procedure is completed in about twenty minutes, potassium-40 counting is potentially of considerable clinical value, though unfortunately the expensive equipment needed at present precludes its extensive use except as a research tool. As part of a research project, we have been making periodic measurements of total body potassium over several years in a group of normal individuals and in patients on treatment with diuretics, most of the latter being hypertensive patients 1,who were taking diuretics (usually a thiazide drug) as part of their hypotensive regime. A convenient way of expressing the results is to state the observed value of total body potassium (K& at any time as a proportion of the untreated or expected value for the individual (Kexp), the latter being usually obtained from measurements made before the individual commences treatment. With normal untreated individuals on a normal diet, we have observed only small fluctuations in total 569