Effect of heart rate on coronary blood flow distribution in dogs

Neill, William A.; Phelps, Nancy C.; Oxendine, John; Mahler, Delmar J.; Sim, David N.

doi:10.1016/s0002-9149(73)80138-9

Cited by 72 publications

(11 citation statements)

References 21 publications

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“…It has been shown previously that distribution of 8-15 /Am radioactively labeled carbonized microspheres around the circumference of the normal canine left ventricle is homogeneous, and that there is a small but significant preferential deposition of these particles in endocardial regions of nonischemic myocardium (29)(30)(31)(32)(33)(34)(35)(36)(37). The findings of the present study are similar in this regard.…”

Section: Discussionsupporting

confidence: 89%

Ischemia-induced alterations in myocardial (Na+ + K+)-ATPase and cardiac glycoside binding.

Conroy¹,

Smith²

1976

J. Clin. Invest.

100

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Section: Discussionsupporting

confidence: 89%

Ischemia-induced alterations in myocardial (Na+ + K+)-ATPase and cardiac glycoside binding.

Conroy¹,

Smith²

1976

J. Clin. Invest.

100

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“…The higher ENDO/EPI ratios observed by Neill and associates, compared with those of the present and previous studies in which microspheres 7-10 /xm in diameter were used, 3i!v~7 -9 may relate to the known property of the larger microspheres to stream toward the subendocardium. 13 ' l4 Nevertheless, both in the study of Neill and associates 12 and in the present study, subendocardial perfusion was maintained equal to or greater than subepicardial perfusion at all heart rates. In addition, as shown in the present study, at every heart rate the flow to layer 4 was significantly higher in dogs receiving adenosine than in the control dogs, indicating that the ability to further increase subendocardial flow by coronary vasodilation had not been exhausted.…”

Section: Discussionsupporting

confidence: 43%

Effect of maximal coronary vasodilation on transmural myocardial perfusion during tachycardia in the awake dog.

Bache

Cobb

1977

Circulation Research

181

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We studied the influence of active coronary vasomotion on transmural myocardial perfusion during tachycardia. Regional myocardial blood flow was estimated in chronically prepared awake dogs by injecting radioactive microspheres (7-10 /xm in diameter) into the left atrium. Studies were performed during ventricular pacing at 100, 150, 200, and 250 beats/min under control conditions with intact coronary vasomotor tone, and during maximal coronary vasodilation induced by intravenous infusion of adenosine. During control conditions, mean myocardial blood flow was 1.27 ± 0.12 ml/min per g of myocardium at a heart rate of 100 beats/min, and increased regularly with increasing heart rates. Transmural myocardial perfusion remained essentially uniform as heart rates were increased from 100 to 250 beats/min. During administration of adenosine, mean myocardial blood flow increased to 5.49 ± 0.39 ml/min per g at a heart rate of 100 beats/min, and transmural myocardial perfusion was uniform. As heart rates were increased, flow to the subendocardium decreased as a linear function of heart rate while subepicardial flow was maintained so that the ratio of subendocardial-subepicardial flow fell from 1.00 at a heart rate of 100 beats/min to 0.40 at a heart rate of 250 beats/min. The reduction of subendocardial perfusion with increasing heart rate was most marked in the deepest myocardial layers. This rate-dependent decrease in subendocardial blood flow resulted in a decrease in mean myocardial blood flow with increasing heart rates (mean change at 250 beats/min = -18%; P < 0.05). These data indicate that active coronary vasomotion is necessary for maintenance of uniform transmural myocardial perfusion during tachycardia.

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“…However, Buckberg and associates, 15 using radionuclide-labeled microspheres 8-10/im in diameter to measure blood flow in open-chest dogs, found that although the mean rate of myocardial blood now increased during pacing-induced tachycardia, uniform transmural distribution of myocardial blood flow was generally maintained at paced rates up to 275 beats/min. Similarly, Neill and associates, 16 using microspheres 15 ± 5 fim in diameter in closed-chest dogs, found only a modest redistribution of transmural flow away from the endocardium during tachycardia. Thus, at a heart rate of 71 beats/min, the endo/epi flow ratio was 1.32; this ratio fell to 1.11 during atrial pacing at 193 beats/min.…”

Section: Discussionmentioning

confidence: 76%

Distribution of myocardial blood flow in the exercising dog with restricted coronary artery inflow.

Ball¹,

Bache²

1976

Circulation Research

106

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SUMMARY The effect of a proximal coronary artery stenosis on transmural myocardial blood flow during exercise was studied in nine dogs with electromagnetic flowmeter probes and hydraulic occluders on the left circumflex coronary artery. Regional myocardial blood flow at rest and during treadmill exercise was estimated with radioactive microspheres 7-10 j»m in diameter. Exercise studies were performed during unrestricted coronary artery inflow (control exercise) and during partial inflation of the occluder to a level which did not reduce flow at rest but which limited the increase in flow during exercise to 66 ± 6% (mild restriction) or 44 ± 3% (severe restriction) of the value during control exercise. Mean myocardial blood flow at rest was 0.94 ± 0.06 rnl/min per g of myocardium and increased to 2.45 ± 0.15 ml/min per g during control exercise, with uniform distribution across the wall of the left ventricle. Flow to the subepicardial myocardium was significantly greater during exercise in the presence of a mild restriction than during control exercise, whereas flow to deeper layers of myocardium was progressively decreased below the control level. A similar pattern of redistribution of flow occurred during exercise in the presence of a severe restriction, but flow to all transmural layers was below that during mild restriction, resulting in more marked subendocardial underperfusion. Thus, exercise in the presence of stenosis resulted in transmural redistribution of myocardial blood flow with subendocardial underperfusion in proportion to the degree of restriction of coronary artery inflow.IN THE presence of occlusive coronary artery disease patients who have normal electrocardiograms at rest may develop S-T segment depression during exercise, often in association with chest pain. This electrocardiographic change suggests that in these patients exercise may result in selective ischemia of the subendocardial myocardium.1 Previous experimental studies in animals have demonstrated that in contrast to the uniform left ventricular perfusion that exists during unimpeded coronary artery inflow, transmural redistribution of flow may occur during restricted inflow. Thus, in open-chest dogs reduction of coronary inflow below the metabolic requirements of the myocardium resulted in transmural redistribution of myocardial blood flow with preferential underperfusion of the subendocardial myocardium.2 " 6In patients with occlusive coronary artery disease, arterial inflow at rest may be adequate and transmural distribution uniform, but because arterial inflow is unable to increase adequately during exercise a similar redistribution of myocardial blood flow may occur with preferential underperfusion of the subendocardial myocardium. The present study was an attempt to determine whether, in an experimental model with a flow-limiting proximal coronary artery stenosis, exercise could result in the proposed redistribution of myocardial blood flow. MethodsNine adult mongrel dogs weighing 22-34 kg were anesthetized with sodium thiamyl...

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Effect of heart rate on coronary blood flow distribution in dogs

Cited by 72 publications

References 21 publications

Ischemia-induced alterations in myocardial (Na+ + K+)-ATPase and cardiac glycoside binding.

Ischemia-induced alterations in myocardial (Na+ + K+)-ATPase and cardiac glycoside binding.

Effect of maximal coronary vasodilation on transmural myocardial perfusion during tachycardia in the awake dog.

Distribution of myocardial blood flow in the exercising dog with restricted coronary artery inflow.

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