Blood flow diversion using the microvascular plug to avoid non target delivery of radioactive microspheres

1. Total renal blood flow and its distribution within the renal cortex of the conscious rabbit were studied with radioactive microspheres of 15 and 25 μm diameter. 2. The reliability of the microsphere technique was influenced by microsphere diameter and number (dose). The optimum microsphere diameter for determination of flow distribution in the rabbit kidney was 15 μm and dose 100–150 000 spheres. 3. Spheres of 15 μm nominal diameter were randomly distributed within the renal cortex of adult rabbits. The larger spheres in batches nominally 15 μm in diameter in young rabbits and 25 μm diameter in adult rabbits were preferentially distributed to the superficial cortex. 4. In adult rabbits 15 μm diameter spheres lodged in glomerular capillaries. Larger spheres occasionally lodged in interlobular arteries causing intrarenal haemorrhage. 5. Microspheres of 15 μm caused a decrease in renal clearance of creatinine and of p-aminohippurate when the total injection dose was about 200 000 spheres. These effects were greater when the injection dose was increased to 500 000 spheres. 6. The reduction in total renal blood flow observed with large doses of spheres largely reflected decreased outer cortical flow, as measured by a second injection of spheres, and confirmed by a decrease in p-aminohippurate extraction. 7. The reproducibility of multiple injection studies was limited by these intrarenal effects of microspheres. 8. Total renal blood flow measured in six rabbits in acute experiments by the microsphere technique was 107 ± 12 (mean±sd) ml/min and by p-aminohippurate clearance was 100 ± 10 ml/min. 9. Total renal blood flow in twelve conscious, chronically instrumented rabbits was 125 ± 11 ml/min, of which 92 ± 6 ml/min was distributed to the superficial cortex and 33 ± 4 ml/min to the deep cortex.

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Testicular Blood Flow in Monkeys as Measured by Xenon Clearance and Radioactive Microspheres

Journal of Medical Primatology ◽

10.1111/j.1600-0684.1985.tb00170.x ◽

1985 ◽

Vol 14 (1) ◽

pp. 49-55

Author(s):

Richard M. Harrison ◽

Ronald W. Lewis ◽

James A. Roberts

Keyword(s):

Blood Flow ◽

Radioactive Microspheres ◽

Testicular Blood Flow ◽

Xenon Clearance

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Microsphere Determination of Cochlear Blood Flow in Chickens

Otolaryngology ◽

10.1177/019459988709600407 ◽

1987 ◽

Vol 96 (4) ◽

pp. 341-348 ◽

Cited By ~ 1

Author(s):

Daniel Zaluzec ◽

Joseph Ramzy ◽

Robert Wotring ◽

Lincoln Gray

Keyword(s):

Blood Flow ◽

Inverse Relationship ◽

External Auditory Meatus ◽

Blood Gas ◽

Radioactive Microspheres ◽

Cochlear Blood Flow ◽

Camera Lucida ◽

Micron Diameter ◽

The Brain

Chickens were injected with 9-micron-diameter radioactive microspheres. Cochleas were removed through the external auditory meatus, and the positions of all embedded microspheres were drawn under camera-lucida. Constant measurements of arterial pressures and postinjection blood-gas determinations confirmed that injections were made into normal circulatory systems. The averaged estimate of cochlear blood flow in chickens is 0.75 μl/min. Variability in these data from chickens is similar to that reported from mammals. A potentially important but puzzling observation is an inverse relationship between blood flow to the cochlea and to the brain. The ease of cochlear extraction makes chickens ideal models for study of cochlear blood flow.

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Fluorescent microspheres are superior to radioactive microspheres in chronic blood flow measurements

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1998.275.1.h110 ◽

1998 ◽

Vol 275 (1) ◽

pp. H110-H115 ◽

Cited By ~ 18

Author(s):

Matthijs F. M. Van Oosterhout ◽

Frits W. Prinzen ◽

S. Sakurada ◽

Robb W. Glenny ◽

J. Robert S. Hales

Keyword(s):

Blood Flow ◽

Liver Blood Flow ◽

Mean Difference ◽

Radioactive Microspheres ◽

Fluorescent Microspheres ◽

Flow Measurements ◽

Change Over Time ◽

Radioactive Microsphere ◽

Blood Flow Measurements ◽

Over Time

The accuracy of the fluorescent (FM) and radioactive microsphere (RM) techniques is similar in acute experiments but has not been established in chronic experiments. In the present study various combinations (at least pairs) of FM and/or RM labels were injected simultaneously between 2 mo and 5 min before each animal was killed. Blood flow was determined in many organs. Intramethod mean difference and variation did not change over time for FM but increased significantly for RM (from 1.8 ± 1.4 to 25.6 ± 21.8% and from 4.4 ± 3.2 to 32.4 ± 23.0% at 5 min and 2 mo, respectively). Also the FM-RM intermethod mean difference and variation increased (from −0.5 ± 8.5 to 40.8 ± 23.8% and from 23.6 ± 4.6 to 71.8 ± 34.3%, respectively). After 2 mo, blood flow estimations were 20–50% lower with the various RM, whereas brain and liver blood flow values varied even more between isotopes. Underestimation started within 1 day for51Cr and within 2 wk for141Ce,95Nb, and85Sr. We conclude that FM are superior to RM for blood flow determination in experiments lasting longer than 1 day, presumably because of leaching of isotopes from RM.

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Discrepancy between microsphere and diffusible tracer estimates of perfusion to ischemic myocardium

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1985.249.2.h255 ◽

1985 ◽

Vol 249 (2) ◽

pp. H255-H264 ◽

Cited By ~ 6

Author(s):

S. Yoshida ◽

S. Akizuki ◽

D. Gowski ◽

J. M. Downey

Keyword(s):

Blood Flow ◽

Coronary Artery ◽

Regional Blood Flow ◽

Distal Segment ◽

Ischemic Myocardium ◽

Flow Diversion ◽

Retrograde Flow ◽

Arterial Blood ◽

Zero Flow ◽

133Xe Washout

This study critically tests the ability of microspheres to accurately measure perfusion to ischemic myocardium. The left anterior descending coronary artery was cannulated and perfused with arterial blood. The perfusion line was clamped, and a sidearm between the clamp and the cannula was opened to the atmosphere, allowing blood to flow retrograde from the distal segment of the artery. Measurement of regional blood flow during retrograde flow diversion with 15-micron microspheres revealed essentially zero flow to the perfused segment (0.005 ml X min-1 X g-1). Measurements under the same conditions by either 86Rb uptake or 133Xe washout revealed that an appreciable perfusion of the tissue persisted during retrograde flow diversion (0.043 and 0.11 ml X min-1 X g-1, respectively, for the 2 methods). Thus we have identified a condition during which microspheres indicate zero flow to the tissue but diffusible tracers can both be washed in and washed out at a brisk rate. We conclude that with simple occlusion there is a hidden component of perfusion to an ischemic zone that cannot be measured by microspheres, causing them to underestimate flow by about 25% in that condition.

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Flow diversion treatment: intra-aneurismal blood flow velocity and WSS reduction are parameters to predict aneurysm thrombosis

Acta Neurochirurgica ◽

10.1007/s00701-012-1482-2 ◽

2012 ◽

Vol 154 (10) ◽

pp. 1827-1834 ◽

Cited By ~ 65

Author(s):

Zsolt Kulcsár ◽

Luca Augsburger ◽

Philippe Reymond ◽

Vitor M. Pereira ◽

Sven Hirsch ◽

...

Keyword(s):

Blood Flow ◽

Flow Velocity ◽

Blood Flow Velocity ◽

Flow Diversion ◽

Aneurysm Thrombosis

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Fetal sheep adrenal blood flow responses to hypoxemia after splanchnicotomy using fluorescent microspheres

Journal of Applied Physiology ◽

10.1152/jappl.1998.84.1.82 ◽

1998 ◽

Vol 84 (1) ◽

pp. 82-89 ◽

Cited By ~ 10

Author(s):

Lynn F. Buchwalder ◽

Michelle Lin ◽

Thomas J. McDonald ◽

Peter W. Nathanielsz

Keyword(s):

Blood Flow ◽

Splanchnic Nerve ◽

Radioactive Microspheres ◽

Fluorescent Microspheres ◽

Nerve Section ◽

Fetal Sheep ◽

Blood Samples ◽

Fluorescent Microsphere ◽

Cont Group ◽

And Control

Buchwalder, Lynn F., Michelle Lin, Thomas J. McDonald, and Peter W. Nathanielsz. Fetal sheep adrenal blood flow responses to hypoxemia after splanchnicotomy using fluorescent microspheres. J. Appl. Physiol. 84(1): 82–89, 1998.—Adrenal gland blood flow (ABF) increases during hypoxemia in fetal sheep, but regulation of ABF is poorly understood. The purpose of this study was to determine the effects of splanchnic nerve section on fetal ABF responses to hypoxemia using the fluorescent microsphere (FM) technique. At 125 days of gestation, 14 unanesthetized fetal sheep [bilateral splanchnicotomy (Splx, n = 6) and control (Cont, n = 8)] were injected with FM before and at 60 min of N2-induced hypoxemia (∼40% decrease in fetal arterial [Formula: see text]). Adrenal tissue and reference blood samples were digested and filtered, and FM dye was extracted for spectrometer analysis. Baseline whole, medullary, and cortical ABF for the Cont group were similar to published values using radioactive microspheres and did not differ from Splx values. Hypoxemia increased whole, medullary, and cortical ABF (mean ± SE) from baseline for the Cont group by 281 ± 35, 258 ± 31, and 496 ± 81% ( P < 0.05). The increase for the Splx group was attenuated compared with the Cont group ( P < 0.05) for whole and medullary ABF (139 ± 27 and 43 ± 27%) but not cortical ABF (326 ± 91%). We conclude that 1) the FM technique is valid for measuring fetal ABF and 2) in fetal sheep the splanchnic nerve is not necessary to maintain basal ABF but plays an important role in regulating the hypoxemia-induced increase in ABF through the medullary, but not cortical, ABF response.

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Distribution of internal carotid artery blood flow in the pony

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1983.244.1.h142 ◽

1983 ◽

Vol 244 (1) ◽

pp. H142-H149 ◽

Cited By ~ 2

Author(s):

J. A. Orr ◽

L. C. Wagerle ◽

A. L. Kiorpes ◽

H. W. Shirer ◽

B. S. Friesen

Keyword(s):

Blood Flow ◽

Carotid Artery ◽

Internal Carotid Artery ◽

Internal Carotid ◽

Electromagnetic Flowmeter ◽

Circle Of Willis ◽

Relative Distribution ◽

Brain Blood Flow ◽

Radioactive Microspheres ◽

Total Brain

This study determined whether blood flow through the internal carotid artery (ICA) could be used to sample total cerebral blood flow in the pony. To answer this question we considered both the anatomic arrangement of the ICA in cadavers and the relative distribution of ICA blood flow to cerebral and extracerebral tissue using radioactive microspheres. Acrylic corrosion casts of the ICA indicated that this vessel traveled directly to the base of the brain, contributing to the formation of the circle of Willis, and did not send any significant branches to other tissues. Two vessels (internal ethmoidal artery and internal ophthalamic artery) did arise anteriorly from the circle of Willis and were, therefore, indirectly supplied by the ICA. Injection of radioactive microspheres of 15 microns diameter indicated that blood flow to extracerebral structures supplied by the internal ethmoidal and internal ophthalamic arteries was less than 5% of total ICA blood flow. Increases in ICA blood flow as measured with an electromagnetic flowmeter during isocapnic hypoxia (arterial PO2 near 40 Torr) in the awake pony (n = 6) were compared with increases in total brain flow as measured with radioactive microspheres (n = 6). ICA blood flow increased 40% compared with a 38% increase in total brain blood flow as measured with microspheres. We conclude that the ICA supplies predominantly brain tissue (approximately 95%) and that changes in ICA blood flow are representative of changes in total brain blood flow in the awake pony.

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Augmenting Regional Cerebral Blood Flow Using External-to-Internal Carotid Artery Flow Diversion Method

Annals of Biomedical Engineering ◽

10.1007/s10439-009-9782-2 ◽

2009 ◽

Vol 37 (12) ◽

pp. 2428-2435 ◽

Cited By ~ 6

Author(s):

Afshin A. Divani ◽

Tamara L. Berezina ◽

Gabriela Vazquez ◽

Sergey B. Zaets ◽

Ramachandra Tummala ◽

...

Keyword(s):

Blood Flow ◽

Cerebral Blood Flow ◽

Carotid Artery ◽

Internal Carotid Artery ◽

Regional Cerebral Blood Flow ◽

Internal Carotid ◽

Flow Diversion ◽

Regional Cerebral Blood ◽

Artery Flow

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Circulatory responses of the near-term sheep fetus to prostaglandin E2

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1976.231.3.760 ◽

1976 ◽

Vol 231 (3) ◽

pp. 760-765 ◽

Cited By ~ 22

Author(s):

JH Rankin ◽

TM Phernetton

Keyword(s):

Blood Flow ◽

Prostaglandin E2 ◽

Time Course ◽

Pressor Response ◽

Radioactive Microspheres ◽

Membrane Flow ◽

Fetal Circulation ◽

Near Term ◽

Hypotensive Response ◽

Sheep Fetus

The effect of prostaglandin E2 (PGE2) on the fetal circulation was measured in chronically catheterized ewes using radioactive microspheres. The injection of 10 mug/kg PGE2 into six fetuses resulted in a biphasic pressor response with a hypotensive period followed by a prolonged period of hypertension. The fetal arterial pressure rose from 45 to 63 mmHg (P less than 0.002). The placental membrane flow changed from 36 to 16 ml/min (P less than 0.004), the fetal renal blood flow changed from 8.6 to 7.1 ml/min per kg of fetus (P less than 0.001). It was postulated that the hypotensive response was due to a direct effect of PGE2 on the heart and the hypertensive response was due to PGE2 releasing a vasoconstricting agent into the fetal circulation. In nine experiments the PGE2 was administered to the maternal lcirculation. This caused a fetal hypertension and a vasoconstriction of the fetal renal, placental membrane, and umbilical circulations. These changes were similar in time course and magnitude to those described above. It is postulated that PGE2 crosses the placenta and that the fetal responses seen in this series are similar to those seen when PGE2 is administered to the fetal circulation.

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