Continuous assessment of regional myocardial perfusion in dogs using krypton-81m.

Selwyn, Andrew P.; Jones, Terry; Turner, Jennifer; Pratt, Tim; Clark, John C.; Lavender, Peter

doi:10.1161/01.res.42.6.771

Cited by 36 publications

(11 citation statements)

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“…The systematic and random errors showed adequate agreement between measured and calculated perfusion. These experiments suggested that the delivered arterial concentration and mixing of 81m Kr were stable over a wide range for heart rate, blood pressure, and cardiac output (Selwyn et al, 1978). This may be explained in part by the particular vortex pattern of blood flow in the aortic sinuses (Bellhouse et al, 1968;Bellhouse and Bellhouse, 1969).…”

Section: Discussionmentioning

confidence: 95%

“…A constant infusion of 81m Kr into the aortic sinuses will result in the accumulation of this tracer in the myocardial water space and an equilibrium of activity within the heart (Selwyn et al, 1978;Kaplan and Mayron, 1976). This inert, freely diffusing radionuclide has been developed for the continuous assessment of changes in regional myocardial perfusion in dogs.…”

Section: Discussionmentioning

confidence: 99%

“…A modified Paulin catheter was introduced via a right femoral arteriotomy and seated in the aortic sinuses (Paulin, 1964 Rb generator and infused into the aortic sinuses of each dog as a constant infusion at between 5 and 10 ml/min (Watson-Marlow MH-RE200, roller pump) (Clark et al, 1976;Turner et al, 1976;Selwyn et al, 1978). Each dog's chest was positioned under a widefiled gamma camera (Toshiba GCA 202) and images were recorded on Polaroid or 35-mm film.…”

Section: Methodsmentioning

confidence: 99%

“…The tracings obtained were reproducible throughout the 5-hour experiments. Epicardial electrograms were recorded through a single saline-soaked cotton electrode held over the myocardium to include the area affected by the snared LAD (Selwyn et al, 1978). The calibration was 1 mm-1 mV.…”

Section: Methodsmentioning

confidence: 99%

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The effects of nifedipine on acute experimental myocardial ischemia and infarction in dogs.

Selwyn¹,

Welman²,

Fox³

et al. 1979

Circulation Research

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SUMMARY We studied 25 anesthetized and thoracotamized dogs before and during 5 hours of acute regional myocardial ischemia. Krypton-81m ( 8Xm Kr) was infused constantly into the aortic sinuses. The myocardial equilibrium of this tracer was used to image and assess the distribution of regional myocardial perfusion using a gamma camera and digital computer. The epicardial ECG was recorded, S-T segment elevation and the loss of R and appearance of Q waves were measured, and the plasma activity of creatine kinase (CK) was determined in aortic and coronary venous blood throughout these experiments. Ten dogs underwent left anterior descending coronary artery (LAD) narrowing for 5 hours and received no drugs. Five dogs received nifedipine 13 fig/kg, and another five received 1.0 /ig/kg intravenously 30 minutes after LAD narrowing. Those dogs receiving nifedipine, 13 fig/kg, showed a 30% fall in aortic pressure, a 12% rise in heart rate, and an extension of regional ischemia. The ECG showed an extension of infarct size, and CK release into the coronary vein appeared earlier than in the controls. Dogs receiving nifedipine, 1 /ig/kg, showed a 12% fall in blood pressure, no rise in heart rate, an improvement in regional perfusion, and ECG signs that suggested limitation of infarct size. There also was delayed release of coronary venous CK. The effects of nifedipine on the natural history of regional myocardial perfusion, the electrocardiogram, and enzyme release from the heart were dose related and cannot be generalized. These observations warrant further clinical investigation to improve the use of this agent in man. Circ Res 44: 16-23, 1979 THE extent of ischemic myocardial damage during acute myocardial infarction is one of the important determinants of morbidity and mortality. Recent studies have encouraged a search for interventions that can affect the balance between energy supply and demand during acute infarction of the heart (Maroko et al., 1971; Braunwald andMaroko, 1974). Nifedipine (4-(2'-nitrophenyl)-2,6-dimethyl-l,4-dihydropyridine-3,5-dicarboxylic acid dimethyl ester) has been shown to retard the transmembrane influx of calcium into ischemic myocardial cells, increase coronary blood flow, delay ischemic contracture, and preserve myocardial creatine kinase activity (Henry, 1975;Fleckenstein, 1975;Vater, 1975;Schmier et al., 1975). These combined pharmacological properties suggest that a favorable effect on acutely ischemic myocardium may be possible.The purpose of this study was to observe the changes of regional myocardial perfusion, the epicardial ECG, and the appearance of creatine kinase activity in coronary venous blood in dogs during the 5 hours following occlusion of the left anterior descending coronary artery (LAD). The dose-related effects of nifedipine on these parameters were measured, and the use of this drug to protect the ischemic myocardium is discussed. MethodsTwenty-five mongrel dogs weighing 30-55 kg were anesthetized with intravenous sodium thiopental (Pentothal, 12 mg/kg). Respiration ...

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Section: Discussionmentioning

confidence: 95%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

The effects of nifedipine on acute experimental myocardial ischemia and infarction in dogs.

Selwyn¹,

Welman²,

Fox³

et al. 1979

Circulation Research

Self Cite

111

View full text Add to dashboard Cite

show abstract

“…Time-activity graphs were calculated by a Deltron-Nova 1220 digital computer and corrected for the decay of rubidium-81 (half-life 4.56 hours). [8][9][10][11][12] A Wilcoxon test for paired differences was used to test changes in end-diastolic pressure, blood pressure and heart rate. An analysis of variance was used to examine the significance of changes in the regional myocardial activity of krypton-81m.…”

Section: Methodsmentioning

confidence: 99%

The effect of acute regional myocardial ischemia on the angiographic anatomy of coronary arteries.

Selwyn¹,

Fox²,

Clay³

1979

Circulation

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SUMMARY Twenty-eight anesthetized dogs were studied to investigate the effects of regional myocardial ischemia on the angiographic appearance of large coronary arteries. Left ventricular (LV) and left coronary angiograms were recorded before and after the diameter of the left anterior descending coronary artery (LAD) was reduced by 60-70%. The left ventricular end-diastolic pressure (LVEDP) and the epicardial ECG showed no regional dyskinesia or ischemia. After the LAD was narrowed, we produced regional ischemia with atrial pacing in eight dogs and with 0.4 mg of ergonovine maleate i.v. in five dogs. Repeat angiograms during each episode of ischemia showed that the LAD associated with the dyskinetic segment transiently failed to opacify. This was reversed by intravenous nitroglycerin. In another five dogs, we produced regional ischemia by injecting microspheres into the LAD. Repeat angiograms showed narrowed vessels and impaired opacification of the associated segment of the LAD. This was partially reversed by intravenous nitroglycerin. A dynamic assessment of changes in regional myocardial perfusion was recorded in 10 more dogs using krypton-81m. Stenosis (60-70%) of the LAD produced no changes in regional perfusion. Atrial pacing produced an immediate redistribution with increases in perfusion (112 ± 14% [mean + SD]) to remote myocardium and decreases (78 ± 9.0%) in the affected segment. These experiments showed that when several interventions are used to produce acute regional myocardial ischemia, the angiographic appearance of the coronary arteries changes. This change consisted of a transient failure to opacify the length of the artery associated with the ischemic segment. This suggests that the reversible disappearance of a large coronary artery during an episode of myocardial ischemia may not necessarily be due to coronary spasm. THE NEED to rationalize the treatment of angina pectoris has encouraged research into the pathophysiology of this condition.' Atherosclerotic narrowing of coronary arteries is thought to limit appropriate changes in regional blood flow needed to meet myocardial metabolism, but this theory does not explain spontaneous angina. Fleckenstein has shown some of the biochemical pathways and responses that influence the tone of coronary artery strips in vitro.

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Myocardial imaging with extractable cations and inert tracers: The effects of flow and metabolism

Selwyn¹,

Fox²,

Shillingford³

1978

Clinical Cardiology

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The physical and biological properties of 201thallium (Tl) have been investigated and are discussed in this review. A new technique using the ultra-short lived 81mkrypton (81mKr) as a continuous infusion into the aortic root in dogs and man is described. This provides a dynamic assessment of changes in regional myocardial perfusion. Experiments using 201Tl and 81mKr in dogs have shown that regional decreases in myocardial perfusion alone cannot be detected in images of the heart using 201Tl. The effects of perfusion and a variety of factors on the energy dependent cellular uptake of 201Tl are discussed as being of primary importance in changing the regional myocardial distribution of this tracer. The constant infusion of 81mKr in patients with anginal chest pain provides continuous measurement of regional myocardial perfusion in high spatial resolution images. This dynamic method provides a physiological assessment of stenosed coronary arteries at rest and during stress.

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Continuous assessment of regional myocardial perfusion in dogs using krypton-81m.

Cited by 36 publications

References 3 publications

The effects of nifedipine on acute experimental myocardial ischemia and infarction in dogs.

The effects of nifedipine on acute experimental myocardial ischemia and infarction in dogs.

The effect of acute regional myocardial ischemia on the angiographic anatomy of coronary arteries.

Myocardial imaging with extractable cations and inert tracers: The effects of flow and metabolism

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