Redistribution of thallium at rest in patients with stable and unstable angina and the effect of coronary artery bypass surgery.

Berger, Bruce C.; Watson, Denny D.; Burwell, Lawrence R.; Crosby, Ivan K.; Wellons, HA; Teates, Charles D.; Beller, George A.

doi:10.1161/01.cir.60.5.1114

Cited by 192 publications

(25 citation statements)

References 23 publications

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“…201 Tl] perfusion images could improve after revascularization 2 or with restredistribution 3 or reinjection. 4 To date, the molecular mechanisms underlying myocardial hibernation have remained elusive.…”

mentioning

confidence: 99%

Myocardial Hibernation

Sawyer

Loscalzo

2002

Circulation

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mentioning

confidence: 99%

Myocardial Hibernation

Sawyer

Loscalzo

2002

Circulation

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“…' 2 The delayed or equilibrium distribution, particularly under conditions of altered perfusion, is less well understood. The determination of relative myocardial thallium concentration as a function of time in sequential imaging studies is being used increasingly to detect and evaluate coronary artery disease.1' [3][4][5][6][7][8][9] The clinical use of delayed thallium redistribution imaging has brought about an acute need for an improved understanding of the mechanism of thallium kinetic exchange and redistribution. Many groups are now using delayed redistribution approach in exercise scintigraphy as a means to improve sensitivity and specificity in the detection of coronary artery disease and suggesting that there is a relationship between thallium redistribution patterns on delayed images and the functional severity of myocardial perfusion abnormalities.…”

mentioning

confidence: 99%

Myocardial thallium-201 kinetics in normal and ischemic myocardium.

Grunwald¹,

Watson

Holzgrefe³

et al. 1981

Circulation

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136

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SUMMARY The initial myocardial uptake of thallium-201 depends on myocardial blood flow distribution. The phenomenon of delayed thallium redistribution after transiently or chronically altered myocardial perfusion has been described. The net myocardial accumulation of thallium-201 after injection depends upon the net balance between continuing myocardial extraction from low levels of recirculating thallium in the blood compartment and the net rate of efflux of thallium from the myocardium into the extracardiac blood pool. These experiments were designed to measure separately the myocardial extraction and intrinsic myocardial efflux of thallium-201 at normal and at reduced rates of myocardial blood flow. The average myocardial extraction fraction at normal blood flow in 10 anesthetized dogs was 82 ± 6% (±SD) at normal coronary arterial perfusion pressures and increased insignificantly, to 85 ± 7%, at coronary perfusion pressures of 10-35 mm Hg. At normal coronary arterial perfusion pressures in 12 additional dogs, the intrinsic thallium washout in the absence of systemic recirculation had a half-time (T½h) of 54 ± 7 minutes. The intrinsic cellular washout rate began to increase as distal perfusion pressures fell below 60 mm Hg and increased markedly to a T½ of 300 minutes at perfusion pressures of 25-30 mm Hg. A second, more rapid component of intrinsic thallium washout (T' 2.5 minutes) representing approximately 7% of the total initially extracted myocardial thallium was observed. The faster washout component is presumed to be due to washout of interstitial thallium unextracted by myocardial cells, whereas the slower component is presumed due to intracellular washout. The net clearance time of thallium measured after 'Lv. injection is much longer than the intrinsic myocardial cellular washout rate because of continuous replacement of myocardial thallium from systemic recirculation. Myocardial redistribution of thallium-201 in states of chronically reduced perfusion cannot be the result of increased myocardial extraction efficiency, but rather, is the result of the slower intrinsic cellular washout rate at reduced perfusion levels.DESPITE the widespread use of thallium-201 perfusion scintigraphy in clinical situations, there remain significant gaps in our knowledge concerning the kinetics of the radionuclide in normal and ischemic myocardium. The initial distribution of thallium in the myocardium immediately after i.v. injection is the result of both blood flow delivery of the tracer to the heart and the extraction of the tracer by the myocardium. ' 2 The delayed or equilibrium distribution, particularly under conditions of altered perfusion, is less well understood. The determination of relative myocardial thallium concentration as a function of time in sequential imaging studies is being used increasingly to detect and evaluate coronary artery disease.1' 3-9 The clinical use of delayed thallium redistribution imaging has brought about an acute need for an improved understanding of the mechanism of thallium kinet...

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“…[1][2][3] Quantitative analysis of the scans in.these patients suggested that 201Tl uptake in hypoperfused, but presumably viable, regions played the dominant role in 201Tl redistribution. 3 4 If correct, the concept of delayed uptake of 201Tl into myocardial regions with subnormal coronary flow is important for two reasons. First, it would aid in identifying ischemic zones in patients with qualitatively normal scans"' and help separate infarct from ischemia.…”

mentioning

confidence: 91%

Gamma camera quantitation of thallium-210 redistribution at rest in a dog model.

Steingart¹,

Bontemps²,

Scheuer³

et al. 1982

Circulation

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tion in a dog model of sustained regional myocardial flow reduction at rest. Materials and MethodsMongrel dogs (average weight 22.5 kg) were premedicated with i.m. morphine sulfate (2 mg/kg), anesthetized with sodium pentobarbital (20 mg/kg) and mechanically ventilated through an endotracheal tube. Additional barbiturates were given whenever necessary. After a left thoracotomy, the proximal left circumflex coronary artery was dissected free (in the first two dogs) to allow placement of a circumferential flow probe, an occluder to produce intermittent zero flow and a distal constrictor. The purpose of this constrictor was to produce a sustained reduction of resting blood flow. In the next five dogs studied, the left anterior descending coronary artery was cannulated distal to its second major branch with an extracorporeal flow probe system connected to the right carotid artery. Flow reduction was adjusted by a screw clamp applied over the Silastic tubing just distal to its exit from the carotid artery. Such a system also allows pressure monitoring of the perfused coronary artery.'0 Intravascular catheters were then placed into the left atrium through its appendage for microsphere injection; into the right atrium for injection of indocyanine green dye (ICG); into the right femoral artery for recording ICG dilution curves (Gilford IR 103) and collecting arterial reference blood during the injection of microspheres; and into the descending thoracic aortic through the left femoral artery for pressure monitoring and collecting duplicate arterial reference blood during microsphere injection. A catheter in the femoral vein allowed infusion of fluid and injection of 201TI.After baseline coronary flow was recorded with the flowmeter, the left circumflex (first two dogs) or the extracorporeal line to the anterior descending coronary artery (next five dogs) was constricted so that resting flow was reduced and held steady. With the thoracotomy left open, the left lung pushed away from the heart and the heart suspended in a pericardial cradle. A gamma camera (Picker Nuclear) with an all-purpose collimator was positioned approximately 6 inches from the lateral surface of the heart and fixed there for the duration of the experiment.Two to three ICG dilution cardiac outputs were then determined. Two million to 4 million microspheres, 15 Am in diameter and labeled with 4"Sc diluted in 10 ml of 6% dextran and 2 drops of Tween, were ultrasonicated to ensure proper mixing. These were slowly injected (15 seconds) into the left atrium while dual reference arterial blood samples were collected (at 10 ml/min for 2 minutes) from the femoral artery and the descending thoracic aorta. Within 5 minutes of the microsphere injection, 1.5 mCi of 201T1 were flushed rapidly (1-2 seconds) into the femoral vein and continuous recording of gamma camera images was begun on a PDP 1134 computer (Digital Equipment Corporation). The computer was programmed to store the gamma camera data in a 64 X 64 pixel matrix in 30-second frames starting 1 minute afte...

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Redistribution of thallium at rest in patients with stable and unstable angina and the effect of coronary artery bypass surgery.

Cited by 192 publications

References 23 publications

Myocardial Hibernation

Myocardial Hibernation

Myocardial thallium-201 kinetics in normal and ischemic myocardium.

Gamma camera quantitation of thallium-210 redistribution at rest in a dog model.

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