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Arterial waves
ARTERIAL WAVES G. F. MAYALL, M.A., M.B., B.CH., F.F.R., D.M.R.D.
Department of Radiology, Radcliffe Infirmary, Oxford T~E contrast medium in an artery during arteriography sometimes shows a pattern of regular transverse striations which give it the appearance of a bamboo or a string of pearls. A bamboo pattern was seen by Wickbom and Bartley (1957) during femoral arteriography after a catheter had been passed down this artery and the pattern disappeared after an intra-arterial injection of Priscol. They attributed it to circular contractions in the wall of the artery. Theander (1960) described four cases in which this pattern was seen during femoral arteriography and he discussed the cause under the title of 'Stationary Arterial Waves'. He observed that the waves occurred proximal to some vascular lesion which impeded the blood flow in the artery and that they did not occur when there was a good collateral circulation. He suggested that longitudinal pressure waves are reflected at a site of obstruction and produce standing waves which become amplified by resonance as in the experiment with Kundt's tube. These pressure waves then deform the wall of the artery producing alternate wide and narrow segments in the lumen. Theander (1963) has since seen waves in several more femoral arteriograms, all but one showing arterial block peripherally and in the iliac arteries proximal to the arterial compression used for pelvic arteriography by Fernstr6m's method (1955).
Sutton (1962) has seen these waves in about a dozen femoral arteriograms, a third of which were in patients with Buergers disease. He reports single examples of waves in the iliac and internal carotid arteries and in the renal artery (Sutton 1963) and more recently has seen a further example in the iliac arteries and two examples in the superior mesenteric artery (Sutton 1964). A similar pattern of waves in a renal artery was interpreted as an early form of fibromuscular hypertrophy by Wylie et al (1962). They also illustrated a case in which waves were seen in a branch of the superior mesenteric artery following the injection of a large bolus of concentrated contrast but were not present later when more dilute contrast was used. At the same meeting, Szilagyi (1962) showed slides of two femoral arteriograms on patients with Buergers disease which showed changes described as resembling a corrugated synthetic graft which were probably due to wave formation. Schechter (1963) saw waves in an internal carotid artery and concluded that they were not due to organic changes in the artery owing to their changing pattern.
TABLE I OLIN (1963), WINTRO~E (1951), LErIMAN ANn DE~BAS (1961) AND MANUFACTURER'S LITERATURE Dynamic Dynamic Viscosity Viscosity Centipoises Centipoises 20 ° C. 37 ° C.
Density gm./cm) at 37 ° C.
H y p a q u e 45 per cent
2.8
1.94
1.29
H y p a q u e 50 per cent Sodium diatrizoate 50 per cent
4
2.3
1 "32
Urografin 60 per cent
7
4
1"33
Urografin 76 per cent
18
8.5
1.41
Blood
--
1.7-3.7
1.052-1.063
water
1
0'695
0.99
FIG. 1 A r t e r i a l waves resembling a string of p e a r l s in two branches of the superior mesenteric artery d u r i n g aortography. 355
356
CLINICAL
Waves occurring in several branches of the superior mesenteric artery during arteriography are illustrated (Fig. 1). It is difficult to accept that an artery, especially when stiffened by degenerative disease, can suffer such extensive and regular deformation by pressure changes within its lumen. Peripheral arteries do not show changes in their lumen due to the pulse wave (Reynolds et al 1952). This is confirmed by an experiment in which the lumen of a freshly excised femoral artery was filled with contrast. The artery was first radiographed with the contrast under a pressure of 100 mm. per Hg. and again when the pressure was raised to 300 mm. per Hg. and no measurable increase was found in the lumen. The pulse pressure wave has a wavelength which is large in relation to the length of the arterial system, and is reflected where an artery is suddenly widened by branching or where its elasticity suddenly decreases (Hamilton and Dow 1939), as at the site of an embolus or atheromatous plaque. The amplitude of the reflected wave is rapidly attenuated by damping. This combination of long wavelength, partial reflection and marked damping makes it impossible for a series of standing pressure waves to occur. The blood flow in arteries, with the exception of the aorta, is laminar (Green 1950) and a stream of dye and a stream of blood remain separate as shown by McDonald and Potter (1951) in the basilar artery of a rabbit and by Potter (1957) in vertebral arteriograms in patients. Schechter and Milton (1963), demonstrated in a glass model that an iodine-containing contrast media tends to form a layer in the most dependant part of the stream because of its high density. Fox and Hugh (1964) found conditions disposing to layering were slowing of the circulation, a heavy contrast medium and the effect of centrifugal force where the stream described a curve. The rate of blood flow in the femoral artery varies considerably during the cardiac cycle (McDonald 1960). There is a rapid acceleration
A
RADIOLOGY
of the flow in systole resulting in a high rate of forward flow. This is followed by an equally rapid deceleration which results in reversal of the flow for a short period at the end of the systole. During diastole forward flow again occurs rising to a much lower peak in mid-diastole. A series of experiments were performed in which a non-turbulent stream of water flowed through a transparent horizontal tube. Urografin 60 per cent, coloured to make it more easily seen, was injected into the stream of water where it formed a separate layer flowing in the lower part of the tube. When the rate of flow of the stream of water was suddenly increased or decreased, ripples were produced in the horizontal interface between the two layers. This occurred because the two fluids differed in viscosity and density and changed speed at different rates. Slipping occurred between the two layers at the interface with the production of ripples in a similar way to that of the wind blowing over water. Such horizontal waves at the surface of a layer of contrast medium when radiographed from above are projected as a series of transverse striations (Figs. 2A and 2B) and variations in the height of the wave produce corresponding variations in width owing to the sloping walls of the tube. It seems probable that waves are generated at the interface between blood and contrast during arteriography in a similar way. Favourable factors for the formation of waves would include a length of artery without branches to disturb the flow; enough contrast of high concentration to form a discrete layer only partly filling the artery, and a slow rate of forward flow and relatively large backflow due to partial occlusion of the artery distally. Vasodilatation results in a reduction of the backflow phase in the femoral artery (McDonald 1960) and this is consistent with the finding that waves often disappeared after an interarterial injection of Priscol. Arterial waves can thus be explained by the interaction of two streams of different density and viscosity undergoing oscillating flow in a horizontal tube. In arteriograms these waves can be recognised
B Fro. 2 A - - F r a m e f r o m a cin6 film t a k e n w i t h a h o r i z o n t a l b e a m s h o w i n g w a v e f o r m a t i o n in the c o n t r a s t in the l o w e r layer. B - - S i m i l a r w a v e s t a k e n w i t h a vertical b e a m s h o w i n g t h e s t r i a t e d effect.
A R T E R I A L WAVES by their regularity and their transient appearance. They should not be confused with fibromuscular h y p e r p l a s i a , a t h e r o m a o r s p a s m o f t h e a r t e r i a l wall. SUMMARY S t a n d i n g a r t e r i a l w a v e s are d i s c u s s e d a n d a n e x p l a n a t i o n w i t h s o m e e x p e r i m e n t a l e v i d e n c e is offered. REFERENCES FERNSTROM,I. (1955). Acta Radiol. Suppl. No. 122. Fox, J. A. & HUGH, A. E. (1964). J. Fac. Radiol. (Lond.), 15, 183. GREEN, H. D. (1950). In Glasser, 0 MedicaIPhysics, Vol. I1, p. 288. Chicago: Year Book Publishers. HAMILTON, W. F. & DOW, P. (1939). Amer. J. Physiol. 125, 48. LEHMAN, J. S. & DEan&S, J. N. (1961). Radiology, 76, 548. McDONALD, D. A. & POTTER, J. M. (1951). J. Physiol. (Lond.), 114, 356.
McDONALD, D. A. (1960). Blood Flow in Arteries. London: Arnold. OLIN, T. (1963). Studies in Angiographie Technique. Lund: Ohlssons. POTTER, J. M. (1957). Proc. R. Soc. Med. 50, 661. REYNOLDS, S. R. M., LIGHT, F. W., AI~a)RAN, G. M. & PRICHARD, M. M. L. (1952). Johns Hopk. Hosp. Bull. 91, 83. SCHECHTER, M. M. & MILTON, E. (1963). Acta Radiol. 1, 427 (New Series). SCHECHTER,M. M. (1963). Acta Radiol. 1,417 (New Series). SUTTON, D. (1962). Arteriography. Edinburgh: Livingstone. SUTTON, D. (1964). Personal communication. SUTTON, D., BRUNTON, F. J., FOOT, E. C. & GUTHRIE, J. (1963). Clin. Radiol. 14~ 381. SZILAGY, D. E. (1962). Ann. Surg. 156, 592. THEANDER, G. (1960). Acta Radiol. 53, 417 THEANDER, G. (1963). Personal communication. WICKBOM, I. & BARTLEY, O. (1957). Acta Radiol. 47, 453. WINTROBE, M. M. (1951). Clinical Haernatology. London: Kimpton. WYLIE, E. J., PERLOFF,D. & WELLINGTON,J. S. (1962). Ann. Surg. 156, 592.
NOTICE FIRST CARIBBEAN CONGRESS OF RADIOLOGY
University of the West Indies, Kingston, Jamaica A CONGRESSfor Radiologists working in the Caribbean area is being organised by the Department of Radiology at the University of the West Indies in conjunction with the Committee on Post-Graduate Studies of the Faculty of Medicine, from the 23rd to the 27th March 1965. Individual morning and afternoon sessions will each be devoted to a particular aspect of radiology. The introductory theme will place emphasis on Geographical Pathology and some comparative aspects of African and Caribbean pathology will be discussed. Outside contributions are planned and eminent speakers from Africa, Canada, the United States and the United Kingdom are expected. This time has been selected towards the end of the tourist season as the climate may be expected to be pleasant. The Committee will be glad to give details of travel and accommodation, and facilities will be provided through the Tourist Board for delegates or their families to visit other parts of the island or to enjoy the sporting activities available in Jamaica. Consideration is now being given to papers for inclusion in the programme. A summary of any contributions that are offered should be received by the Committee not later than December of this year. A fee of £5 5s. ($15 U.S.) will be payable on registration before the opening ceremony. Further information may be obtained from the Secretary, B. Tomlinson, Department of Radiology, University of the West Indies.
E(16)
357
Department of Radiology, Radcliffe Infirmary, Oxford T~E contrast medium in an artery during arteriography sometimes shows a pattern of regular transverse striations which give it the appearance of a bamboo or a string of pearls. A bamboo pattern was seen by Wickbom and Bartley (1957) during femoral arteriography after a catheter had been passed down this artery and the pattern disappeared after an intra-arterial injection of Priscol. They attributed it to circular contractions in the wall of the artery. Theander (1960) described four cases in which this pattern was seen during femoral arteriography and he discussed the cause under the title of 'Stationary Arterial Waves'. He observed that the waves occurred proximal to some vascular lesion which impeded the blood flow in the artery and that they did not occur when there was a good collateral circulation. He suggested that longitudinal pressure waves are reflected at a site of obstruction and produce standing waves which become amplified by resonance as in the experiment with Kundt's tube. These pressure waves then deform the wall of the artery producing alternate wide and narrow segments in the lumen. Theander (1963) has since seen waves in several more femoral arteriograms, all but one showing arterial block peripherally and in the iliac arteries proximal to the arterial compression used for pelvic arteriography by Fernstr6m's method (1955).
Sutton (1962) has seen these waves in about a dozen femoral arteriograms, a third of which were in patients with Buergers disease. He reports single examples of waves in the iliac and internal carotid arteries and in the renal artery (Sutton 1963) and more recently has seen a further example in the iliac arteries and two examples in the superior mesenteric artery (Sutton 1964). A similar pattern of waves in a renal artery was interpreted as an early form of fibromuscular hypertrophy by Wylie et al (1962). They also illustrated a case in which waves were seen in a branch of the superior mesenteric artery following the injection of a large bolus of concentrated contrast but were not present later when more dilute contrast was used. At the same meeting, Szilagyi (1962) showed slides of two femoral arteriograms on patients with Buergers disease which showed changes described as resembling a corrugated synthetic graft which were probably due to wave formation. Schechter (1963) saw waves in an internal carotid artery and concluded that they were not due to organic changes in the artery owing to their changing pattern.
TABLE I OLIN (1963), WINTRO~E (1951), LErIMAN ANn DE~BAS (1961) AND MANUFACTURER'S LITERATURE Dynamic Dynamic Viscosity Viscosity Centipoises Centipoises 20 ° C. 37 ° C.
Density gm./cm) at 37 ° C.
H y p a q u e 45 per cent
2.8
1.94
1.29
H y p a q u e 50 per cent Sodium diatrizoate 50 per cent
4
2.3
1 "32
Urografin 60 per cent
7
4
1"33
Urografin 76 per cent
18
8.5
1.41
Blood
--
1.7-3.7
1.052-1.063
water
1
0'695
0.99
FIG. 1 A r t e r i a l waves resembling a string of p e a r l s in two branches of the superior mesenteric artery d u r i n g aortography. 355
356
CLINICAL
Waves occurring in several branches of the superior mesenteric artery during arteriography are illustrated (Fig. 1). It is difficult to accept that an artery, especially when stiffened by degenerative disease, can suffer such extensive and regular deformation by pressure changes within its lumen. Peripheral arteries do not show changes in their lumen due to the pulse wave (Reynolds et al 1952). This is confirmed by an experiment in which the lumen of a freshly excised femoral artery was filled with contrast. The artery was first radiographed with the contrast under a pressure of 100 mm. per Hg. and again when the pressure was raised to 300 mm. per Hg. and no measurable increase was found in the lumen. The pulse pressure wave has a wavelength which is large in relation to the length of the arterial system, and is reflected where an artery is suddenly widened by branching or where its elasticity suddenly decreases (Hamilton and Dow 1939), as at the site of an embolus or atheromatous plaque. The amplitude of the reflected wave is rapidly attenuated by damping. This combination of long wavelength, partial reflection and marked damping makes it impossible for a series of standing pressure waves to occur. The blood flow in arteries, with the exception of the aorta, is laminar (Green 1950) and a stream of dye and a stream of blood remain separate as shown by McDonald and Potter (1951) in the basilar artery of a rabbit and by Potter (1957) in vertebral arteriograms in patients. Schechter and Milton (1963), demonstrated in a glass model that an iodine-containing contrast media tends to form a layer in the most dependant part of the stream because of its high density. Fox and Hugh (1964) found conditions disposing to layering were slowing of the circulation, a heavy contrast medium and the effect of centrifugal force where the stream described a curve. The rate of blood flow in the femoral artery varies considerably during the cardiac cycle (McDonald 1960). There is a rapid acceleration
A
RADIOLOGY
of the flow in systole resulting in a high rate of forward flow. This is followed by an equally rapid deceleration which results in reversal of the flow for a short period at the end of the systole. During diastole forward flow again occurs rising to a much lower peak in mid-diastole. A series of experiments were performed in which a non-turbulent stream of water flowed through a transparent horizontal tube. Urografin 60 per cent, coloured to make it more easily seen, was injected into the stream of water where it formed a separate layer flowing in the lower part of the tube. When the rate of flow of the stream of water was suddenly increased or decreased, ripples were produced in the horizontal interface between the two layers. This occurred because the two fluids differed in viscosity and density and changed speed at different rates. Slipping occurred between the two layers at the interface with the production of ripples in a similar way to that of the wind blowing over water. Such horizontal waves at the surface of a layer of contrast medium when radiographed from above are projected as a series of transverse striations (Figs. 2A and 2B) and variations in the height of the wave produce corresponding variations in width owing to the sloping walls of the tube. It seems probable that waves are generated at the interface between blood and contrast during arteriography in a similar way. Favourable factors for the formation of waves would include a length of artery without branches to disturb the flow; enough contrast of high concentration to form a discrete layer only partly filling the artery, and a slow rate of forward flow and relatively large backflow due to partial occlusion of the artery distally. Vasodilatation results in a reduction of the backflow phase in the femoral artery (McDonald 1960) and this is consistent with the finding that waves often disappeared after an interarterial injection of Priscol. Arterial waves can thus be explained by the interaction of two streams of different density and viscosity undergoing oscillating flow in a horizontal tube. In arteriograms these waves can be recognised
B Fro. 2 A - - F r a m e f r o m a cin6 film t a k e n w i t h a h o r i z o n t a l b e a m s h o w i n g w a v e f o r m a t i o n in the c o n t r a s t in the l o w e r layer. B - - S i m i l a r w a v e s t a k e n w i t h a vertical b e a m s h o w i n g t h e s t r i a t e d effect.
A R T E R I A L WAVES by their regularity and their transient appearance. They should not be confused with fibromuscular h y p e r p l a s i a , a t h e r o m a o r s p a s m o f t h e a r t e r i a l wall. SUMMARY S t a n d i n g a r t e r i a l w a v e s are d i s c u s s e d a n d a n e x p l a n a t i o n w i t h s o m e e x p e r i m e n t a l e v i d e n c e is offered. REFERENCES FERNSTROM,I. (1955). Acta Radiol. Suppl. No. 122. Fox, J. A. & HUGH, A. E. (1964). J. Fac. Radiol. (Lond.), 15, 183. GREEN, H. D. (1950). In Glasser, 0 MedicaIPhysics, Vol. I1, p. 288. Chicago: Year Book Publishers. HAMILTON, W. F. & DOW, P. (1939). Amer. J. Physiol. 125, 48. LEHMAN, J. S. & DEan&S, J. N. (1961). Radiology, 76, 548. McDONALD, D. A. & POTTER, J. M. (1951). J. Physiol. (Lond.), 114, 356.
McDONALD, D. A. (1960). Blood Flow in Arteries. London: Arnold. OLIN, T. (1963). Studies in Angiographie Technique. Lund: Ohlssons. POTTER, J. M. (1957). Proc. R. Soc. Med. 50, 661. REYNOLDS, S. R. M., LIGHT, F. W., AI~a)RAN, G. M. & PRICHARD, M. M. L. (1952). Johns Hopk. Hosp. Bull. 91, 83. SCHECHTER, M. M. & MILTON, E. (1963). Acta Radiol. 1, 427 (New Series). SCHECHTER,M. M. (1963). Acta Radiol. 1,417 (New Series). SUTTON, D. (1962). Arteriography. Edinburgh: Livingstone. SUTTON, D. (1964). Personal communication. SUTTON, D., BRUNTON, F. J., FOOT, E. C. & GUTHRIE, J. (1963). Clin. Radiol. 14~ 381. SZILAGY, D. E. (1962). Ann. Surg. 156, 592. THEANDER, G. (1960). Acta Radiol. 53, 417 THEANDER, G. (1963). Personal communication. WICKBOM, I. & BARTLEY, O. (1957). Acta Radiol. 47, 453. WINTROBE, M. M. (1951). Clinical Haernatology. London: Kimpton. WYLIE, E. J., PERLOFF,D. & WELLINGTON,J. S. (1962). Ann. Surg. 156, 592.
NOTICE FIRST CARIBBEAN CONGRESS OF RADIOLOGY
University of the West Indies, Kingston, Jamaica A CONGRESSfor Radiologists working in the Caribbean area is being organised by the Department of Radiology at the University of the West Indies in conjunction with the Committee on Post-Graduate Studies of the Faculty of Medicine, from the 23rd to the 27th March 1965. Individual morning and afternoon sessions will each be devoted to a particular aspect of radiology. The introductory theme will place emphasis on Geographical Pathology and some comparative aspects of African and Caribbean pathology will be discussed. Outside contributions are planned and eminent speakers from Africa, Canada, the United States and the United Kingdom are expected. This time has been selected towards the end of the tourist season as the climate may be expected to be pleasant. The Committee will be glad to give details of travel and accommodation, and facilities will be provided through the Tourist Board for delegates or their families to visit other parts of the island or to enjoy the sporting activities available in Jamaica. Consideration is now being given to papers for inclusion in the programme. A summary of any contributions that are offered should be received by the Committee not later than December of this year. A fee of £5 5s. ($15 U.S.) will be payable on registration before the opening ceremony. Further information may be obtained from the Secretary, B. Tomlinson, Department of Radiology, University of the West Indies.
E(16)
357