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Arteriosclerosis in high-pressure and low-pressure coronary arteries
Annotations
Arteriosclerosis high-pressure
in and luw-pressure
In spite of recent emphasis on the role of lipids in the pathogenesis of arteriosclerosis, an increase in arterial pressure is one factor which is concerned with the pathogenesis of arteriosclerosis. Many examples of the etiological relationship of hypertension to the development of arteriosclerotic lesions have been cited.’ We wish to describe an interesting and almost ideal “experiment” performed by nature which lends further support to the importance of intravascular pressure in the pathogenesis of arteriosclerosis. Occasionally, one coronary artery arises from the pulmonary artery, while the other coronary artery arises in a normal manner from the aorta. Usually, it is the left coronary artery which arises from the pulmonary artery. This anomaly is rarely compatible with more than a few months of life. However, we are aware of 17 instances in which patients with this defect survived until adulthood.* On the other hand, the opposite situation, in which the right coronary artery arises from the pulmonary artery, is compatible with normal life expectancy. This defect is exceedingly rare; only 5 cases have been reported.* Obviously, the coronary artery which arises from the aorta is subjected to much higher intravascular pressures than the one which arises from the pulmonary artery. However, the lipid content of the blood which flows through the two vessels will be identical. Thus, nature has established a wellcontrolled “experiment” which consists of a coronary artery that contains blood at low pressure and, in the same heart, a coronary artery in which the intravascular pressure is high. Fortunately, this important experimental preparation has been allowed to go on for many years of life in a small group of people. Furthermore, nature has varied the “experiment” so that in some instances the right coronary artery is the high-pressure artery, whereas in other instances the left coronary artery is the high-pressure one. A study of the necropsy material from patients with these anomalies was all that was needed to reap the fruit of the “experiment.” When the left coronary artery originates from the pulmonary artery, the vessel is arterial in nature but thin walled and in some respects vein-like, whereas the right coronary artery is thick walled, tortuous, and has the usual histologic characteristics of a coronary artery. The left anomalous coronary artery may show intimal hyperplasia, thickening of
720
coronary
arteries
the internal elastic membrane, and thinning of the media due to loss of smooth muscle, but atheroma are not seen. However, in the same patient the right coronary artery, which arises from the aorta, may show streaks and spots of atheroma*e* or even marked arteriosclerosis.6 When the right coronary artery arises from the pulmonary artery, then this vessel is thin walled and free of atheroma, whereas the left coronary artery, which arises from the aorta, is thick walled and has arteriosclerotic changes6 The degree of coronary arteriosclerosis was greatest in those instances in which the left coronary artery originated from the aorta. This is probably due to the fact that the patients with this lesion survived longer (average, 62 years) than did the 17 patients in whom the right coronary artery arose from the aorta, who attained an average adulthood of 35 years. In fact, one patient in whom the left coronary artery arose from the aorta and the right coronary artery arose from the pulmonary artery survived to 90 years of age. The left coronary artery of this patient was markedly arteriosclerotic, whereas the right coronary artery was completely free of arteriosclerosis6 in spite of his extreme age. These observations show that intravascular pressure is of paramount importance in the formation of arteriosclerotic lesions. The severity of the lesions is also shown by these “experiments” of nature to be directly related to the duration of time over which the pressure acts. Certainly, the lipid state must have been the same for the coronary vessel with anomalous origin as for the vessel with the normal origin. It is unlikely that differences in oxygen content between the two arteries was a significant factor, since atheroma form in the pulmonary arteries when pulmonary hypertension develops. The thickened intima of the anomalous artery should tend to encourage rather than discourage the formation of atheroma. Thus, one is led to the logical conclusion that the low intravascular pressure in the coronary artery which originated from the pulmonary artery “protected” the vessel from arteriosclerosis, the lipid content of the blood circulating within the vessel notwithstanding. George E. Burch, M.D. Nicholas P. DePasquale, M.D. Tulane University School of Medicine New Orleans, La.
Volume Number
63 5
Annotations
REFERENCES
4.
1.
Burch, G. E., and Phillips, J. H.: Hypertension and arteriosclerosis, AM. HEART J. 60:163, 1960. 2. Burch, G. E., and DePasquaIe, N. P.: Anomalous coronary arteries. (To be published.) 3. Dietrich, W.: Ursprung der vorderen Kranzarterie aus der Lungenschlagader mit ungewbhnlichen Versnderungen des Herzmuskels und der Gefbswlnde, Arch. path. Anat. 303:436, 1938.
More
efficient
It has tions stances storage. bond tissue implies and in
and
become apparent from the that the physiologic activity is modified by the process Binding is conceived of as between the active substance constituent, usually a protein, cellular participation in the subsequent release of the
George, J. M., and Knowlan, D. M.: Anomalous origin of the left coronary artery from the pulmonary artery in an adult, New England J. Med. 261:993, 1959. 5. Gouley, B. A.: Anomalous left coronary artery arising from pulmonary artery (adult type), AM. HEART J. 40:630, 1950. 6. Cronk, E. S., Sinclair, J, G., and Rigdon, R. H.: Anomalous coronary artery arising from pulmonary artery, AM. HEART J. 42:906. 1951.
dialysis
Hemodialysis is now generally accepted as an integral part of the treatment of the more severe forms of acute renal failure, but a healthy interest in developing improved apparatus remains. The efficiency of a new rotating-drum artificial kidney,’ with a surface area of cellophane of 3.2 square meters, has been assessed* in 10 patients undergoing dialysis for the treatment of acute renal failure of various etiologies. Efficiency was assessed on the basis of percentage fall in the levels of plasma urea, total urea removed from the rinsing fluid, and clearance of urea. This was supplemented by studies on the removal of three other, more slowly diffusible metabolites-creatinine, uric acid, and inorganic phosphate-which are perhaps of more importance than urea in the complex biochemical disorder of uremia. The studies clearly show that significantly larger amounts of diffusible metabolites can be removed by this new apparatus in 4% hours of dialysis than by the twin-coil disposable artificial kidney in 6 hours, and as much in 3 hours. Increased efficiency has been achieved without prolonging the time required to assemble the machine, and without increasing the amount of priming blood required (1,080 ml.). The initial cost of the machine is higher than for the twin-coil apparatus but is soon offset by the much lower running
Binding
721
costs (about one tenth) for the disposable parts. Short, effective dialyses are less fatiguing for the patient and less time-consuming for the staff, and dialysis has to be performed less often. These considerations are particularly cogent in cases in which catabolism is intense. In addition to these immediate considerations, it is hoped that the use of a more efficient dialyzer may lead to a further reduction in the mortality due to acute tubular necrosis, especially that of surgical origin, the variety which currently has the worst prognosis. A. C. Kennedy, M.b.,F.R.C.P.Ed. Uniersity Department of Medicine and Artificial Kidney Unit, Royal Injirmary Glasgow, Scotland REFERENCES Parsons, F. M., Hobson, S. M., Blagg, C. R., and McCracken, B. H.: Ootimum time for dialysis in acute’ reversible renal failure. Description and value of an improved dialyzer wifh large surface area, Lanc& 1:129, 1961. Kennedv. _ A. C.. Grav. < M. T. B.. Dinwoodie. A., and Linton, A. L.: RemoGal oi urea, creati: nine, uric acid, and inorganic phosphate by a rotating-drum artificial kidney, Lancet 2:996, 1961.
storage
recent investigaof many subof binding and a loose chemical and a blood or whereas storage the inactivation active substance.
The distinction is largely a semantic one since the process of storage always requires binding and merely implies more elaborate chemical processes, which are usually intracellular. Both words imply that the substances bound or stored will be available for subsequent release chemically intact. The tissue specificity of this binding or storage with reference to certain chemical substances is
Arteriosclerosis high-pressure
in and luw-pressure
In spite of recent emphasis on the role of lipids in the pathogenesis of arteriosclerosis, an increase in arterial pressure is one factor which is concerned with the pathogenesis of arteriosclerosis. Many examples of the etiological relationship of hypertension to the development of arteriosclerotic lesions have been cited.’ We wish to describe an interesting and almost ideal “experiment” performed by nature which lends further support to the importance of intravascular pressure in the pathogenesis of arteriosclerosis. Occasionally, one coronary artery arises from the pulmonary artery, while the other coronary artery arises in a normal manner from the aorta. Usually, it is the left coronary artery which arises from the pulmonary artery. This anomaly is rarely compatible with more than a few months of life. However, we are aware of 17 instances in which patients with this defect survived until adulthood.* On the other hand, the opposite situation, in which the right coronary artery arises from the pulmonary artery, is compatible with normal life expectancy. This defect is exceedingly rare; only 5 cases have been reported.* Obviously, the coronary artery which arises from the aorta is subjected to much higher intravascular pressures than the one which arises from the pulmonary artery. However, the lipid content of the blood which flows through the two vessels will be identical. Thus, nature has established a wellcontrolled “experiment” which consists of a coronary artery that contains blood at low pressure and, in the same heart, a coronary artery in which the intravascular pressure is high. Fortunately, this important experimental preparation has been allowed to go on for many years of life in a small group of people. Furthermore, nature has varied the “experiment” so that in some instances the right coronary artery is the high-pressure artery, whereas in other instances the left coronary artery is the high-pressure one. A study of the necropsy material from patients with these anomalies was all that was needed to reap the fruit of the “experiment.” When the left coronary artery originates from the pulmonary artery, the vessel is arterial in nature but thin walled and in some respects vein-like, whereas the right coronary artery is thick walled, tortuous, and has the usual histologic characteristics of a coronary artery. The left anomalous coronary artery may show intimal hyperplasia, thickening of
720
coronary
arteries
the internal elastic membrane, and thinning of the media due to loss of smooth muscle, but atheroma are not seen. However, in the same patient the right coronary artery, which arises from the aorta, may show streaks and spots of atheroma*e* or even marked arteriosclerosis.6 When the right coronary artery arises from the pulmonary artery, then this vessel is thin walled and free of atheroma, whereas the left coronary artery, which arises from the aorta, is thick walled and has arteriosclerotic changes6 The degree of coronary arteriosclerosis was greatest in those instances in which the left coronary artery originated from the aorta. This is probably due to the fact that the patients with this lesion survived longer (average, 62 years) than did the 17 patients in whom the right coronary artery arose from the aorta, who attained an average adulthood of 35 years. In fact, one patient in whom the left coronary artery arose from the aorta and the right coronary artery arose from the pulmonary artery survived to 90 years of age. The left coronary artery of this patient was markedly arteriosclerotic, whereas the right coronary artery was completely free of arteriosclerosis6 in spite of his extreme age. These observations show that intravascular pressure is of paramount importance in the formation of arteriosclerotic lesions. The severity of the lesions is also shown by these “experiments” of nature to be directly related to the duration of time over which the pressure acts. Certainly, the lipid state must have been the same for the coronary vessel with anomalous origin as for the vessel with the normal origin. It is unlikely that differences in oxygen content between the two arteries was a significant factor, since atheroma form in the pulmonary arteries when pulmonary hypertension develops. The thickened intima of the anomalous artery should tend to encourage rather than discourage the formation of atheroma. Thus, one is led to the logical conclusion that the low intravascular pressure in the coronary artery which originated from the pulmonary artery “protected” the vessel from arteriosclerosis, the lipid content of the blood circulating within the vessel notwithstanding. George E. Burch, M.D. Nicholas P. DePasquale, M.D. Tulane University School of Medicine New Orleans, La.
Volume Number
63 5
Annotations
REFERENCES
4.
1.
Burch, G. E., and Phillips, J. H.: Hypertension and arteriosclerosis, AM. HEART J. 60:163, 1960. 2. Burch, G. E., and DePasquaIe, N. P.: Anomalous coronary arteries. (To be published.) 3. Dietrich, W.: Ursprung der vorderen Kranzarterie aus der Lungenschlagader mit ungewbhnlichen Versnderungen des Herzmuskels und der Gefbswlnde, Arch. path. Anat. 303:436, 1938.
More
efficient
It has tions stances storage. bond tissue implies and in
and
become apparent from the that the physiologic activity is modified by the process Binding is conceived of as between the active substance constituent, usually a protein, cellular participation in the subsequent release of the
George, J. M., and Knowlan, D. M.: Anomalous origin of the left coronary artery from the pulmonary artery in an adult, New England J. Med. 261:993, 1959. 5. Gouley, B. A.: Anomalous left coronary artery arising from pulmonary artery (adult type), AM. HEART J. 40:630, 1950. 6. Cronk, E. S., Sinclair, J, G., and Rigdon, R. H.: Anomalous coronary artery arising from pulmonary artery, AM. HEART J. 42:906. 1951.
dialysis
Hemodialysis is now generally accepted as an integral part of the treatment of the more severe forms of acute renal failure, but a healthy interest in developing improved apparatus remains. The efficiency of a new rotating-drum artificial kidney,’ with a surface area of cellophane of 3.2 square meters, has been assessed* in 10 patients undergoing dialysis for the treatment of acute renal failure of various etiologies. Efficiency was assessed on the basis of percentage fall in the levels of plasma urea, total urea removed from the rinsing fluid, and clearance of urea. This was supplemented by studies on the removal of three other, more slowly diffusible metabolites-creatinine, uric acid, and inorganic phosphate-which are perhaps of more importance than urea in the complex biochemical disorder of uremia. The studies clearly show that significantly larger amounts of diffusible metabolites can be removed by this new apparatus in 4% hours of dialysis than by the twin-coil disposable artificial kidney in 6 hours, and as much in 3 hours. Increased efficiency has been achieved without prolonging the time required to assemble the machine, and without increasing the amount of priming blood required (1,080 ml.). The initial cost of the machine is higher than for the twin-coil apparatus but is soon offset by the much lower running
Binding
721
costs (about one tenth) for the disposable parts. Short, effective dialyses are less fatiguing for the patient and less time-consuming for the staff, and dialysis has to be performed less often. These considerations are particularly cogent in cases in which catabolism is intense. In addition to these immediate considerations, it is hoped that the use of a more efficient dialyzer may lead to a further reduction in the mortality due to acute tubular necrosis, especially that of surgical origin, the variety which currently has the worst prognosis. A. C. Kennedy, M.b.,F.R.C.P.Ed. Uniersity Department of Medicine and Artificial Kidney Unit, Royal Injirmary Glasgow, Scotland REFERENCES Parsons, F. M., Hobson, S. M., Blagg, C. R., and McCracken, B. H.: Ootimum time for dialysis in acute’ reversible renal failure. Description and value of an improved dialyzer wifh large surface area, Lanc& 1:129, 1961. Kennedv. _ A. C.. Grav. < M. T. B.. Dinwoodie. A., and Linton, A. L.: RemoGal oi urea, creati: nine, uric acid, and inorganic phosphate by a rotating-drum artificial kidney, Lancet 2:996, 1961.
storage
recent investigaof many subof binding and a loose chemical and a blood or whereas storage the inactivation active substance.
The distinction is largely a semantic one since the process of storage always requires binding and merely implies more elaborate chemical processes, which are usually intracellular. Both words imply that the substances bound or stored will be available for subsequent release chemically intact. The tissue specificity of this binding or storage with reference to certain chemical substances is