Transmural changes in porcine and canine hearts after circumflex artery occlusion

1984 ◽  
Vol 246 (4) ◽  
pp. H601-H607
Author(s):  
K. H. McDonough ◽  
R. B. Dunn ◽  
D. M. Griggs
Keyword(s):  
Blood Flow ◽  
Coronary Artery ◽  
Tissue Sample ◽  
Outer Wall ◽  
Coronary Artery Occlusion ◽  
High Energy ◽  
Artery Occlusion ◽  
Ventricular Wall ◽  
High Energy Phosphates ◽  
Circumflex Artery

The distribution of the coronary collateral circulation is an important determinant of the myocardial response to acute coronary artery occlusion. The dog shows an unequal response across the ventricular wall, whereas the pig seems to have more uniform transmural changes. This study was undertaken to compare the metabolic and blood flow response in pigs and dogs to acute occlusion of the circumflex artery. Microspheres (8-10 micron) were used to determine control blood flow and flow 5 min after occlusion. A transmural tissue sample from the center of the ischemic zone was taken at 8 min after occlusion, and inner, middle, and outer layers were analyzed for high-energy phosphates and lactate. The remainder of the heart was analyzed for microsphere distribution. The epicardium in the dog showed less severe damage than the subendocardium. High-energy phosphates were higher and lactate lower in this region. In the pig high-energy phosphates and lactate were the same in the subepicardium and subendocardium. Blood flow to regions surrounding the central ischemic zone in pigs was generally uniform across the ventricular wall or greater in the inner wall than in the outer wall. These results verify that dogs as a group have a greater subepicardial protection during coronary artery occlusion. Pigs, however, demonstrate uniform ischemia or even slightly less severe ischemia in the subendocardium in regions of restricted blood flow.

Early changes in collateral blood flow during myocardial infarction in conscious dogs

1979 ◽  
Vol 237 (3) ◽  
pp. H371-H380
Author(s):  
B. I. Jugdutt ◽  
L. C. Becker ◽  
G. M. Hutchins
Keyword(s):  
Myocardial Infarction ◽  
Blood Flow ◽  
Coronary Artery ◽  
Coronary Artery Occlusion ◽  
Artery Occlusion ◽  
Conscious Dogs ◽  
Collateral Blood Flow ◽  
Radioactive Microspheres ◽  
Circumflex Artery ◽  
Over Time

We studied the early changes in collateral blood flow (CBF) after acute coronary artery occlusion and the relation of these changes to subsequent necrosis. We measured CBF with 7--9 microns radioactive microspheres before and at various times after circumflex artery occlusion in 42 conscious dogs that were killed 48 h later. CBF increased from 20 s postocclusion to later measurements (5 min, 15 min, 1 h, or 6 h) and did so in both necrotic and nonnecrotic areas of the occluded bed. However, the increase in CBF over time was not gradual, but appeared to occur between 20 s and 5 min, with no further changes for up to 6 h. There was a gradation of CBF in the occluded bed, from periphery to center and subepicardium to subendocardium. Central and subendocardial regions with CBF less than 0.40 ml-min-1-g-1 at 5--15 min postocclusion subsequently showed necrosis whereas epicardial and lateral regions with CBF greater than 0.50 ml/min did not. Thus CBF increases very early throughout the occluded coronary bed, and the level of CBF by 5 min appears to determine whether necrosis ultimately occurs.

Effect of ethyl adenosine on myocardial flow after coronary artery occlusion

1976 ◽  
Vol 231 (5) ◽  
pp. 1495-1500 ◽  
Author(s):  
DB Hellmann ◽  
B Pitt
Keyword(s):  
Blood Flow ◽  
Coronary Artery ◽  
Myocardial Blood Flow ◽  
Coronary Artery Occlusion ◽  
Artery Occlusion ◽  
Circumflex Artery ◽  
Collateral Development ◽  
Left Circumflex Artery ◽  
And Control ◽  
Myocardial Flow

The effect of ethyl adenosine-5'-carboxylate hydrochloride (EA) was determined in 17 dogs by the radioactive microsphere technique. In both experimental and control animals, microspheres were injected 5 min before (preocclusion period), 60 min after (occlusion period), and 75 min after (saline or vasodilation period) ligation of the left anterior descending coronary artery (LAD). Ten seconds prior to the third microsphere injection, saline was administered to five control animals, and saline with 0.5 mg/kg of EA was given to 12 experimental animals. There was no significant change in myocardial blood flow after saline injection. After EA, mean arterial pressure fell 10% (P less than .001); myocardial blood flow increased 275% (P less than .001) in the nonischemic left circumflex artery (CIRC) area and increased 82% (P less than .01) in the occluded LAD area. In addition, those animals with extensive collateral development showed a significantly greater increase in collateral blood flow than those with minimal collateral development (P less than .05). Thus, EA may increase flow to ischemic areas of myocardium dependent upon the extent of preexistent collateral supply.

Tyrosine hydroxylase and choline acetyltransferase activities in ischemic canine heart

1982 ◽  
Vol 243 (5) ◽  
pp. H788-H795 ◽  
Author(s):  
P. G. Schmid ◽  
B. J. Greif ◽  
D. D. Lund ◽  
R. Roskoski
Keyword(s):  
Blood Flow ◽  
Coronary Artery ◽  
Tyrosine Hydroxylase ◽  
Choline Acetyltransferase ◽  
Coronary Artery Occlusion ◽  
Artery Occlusion ◽  
Canine Heart ◽  
Parasympathetic Innervation ◽  
Ischemic Tissue ◽  
Biochemical Indices

After coronary artery occlusion, enzymes involved in the synthesis of sympathetic and parasympathetic neurotransmitters may change disparately. We investigated this in the canine heart by measuring the activity of tyrosine hydroxylase (TH) and choline acetyltransferase (CAT) in normal and ischemic tissue. Myocardial blood flow in selected regions was measured by the microsphere technique. Dogs had either ligation of the anterior descending coronary artery (LAD) or sham ligation (S). In the ischemic zone 5 h after LAD ligation, TH activity was lower than in corresponding anterior apical zones of S dogs (5.1 +/- 1.7 vs. 13.5 +/- 2.3 nmol.g-1.h-1) (P less than 0.05) with a tendency for greater decreases in endocardium than in epicardium. In contrast, there were insignificant changes in CAT activity 2.5 and 5 h after LAD ligation. Thereafter, progressive and significant (P less than 0.05) decreases occurred in CAT activity at 25 and 170 h after LAD ligation. Thus there are early heterogeneous decreases in TH activity that correlate directly with heterogeneous deficits in blood flow. Although decreases in CAT are also heterogeneous and correlate with deficits in perfusion, these changes occur later. These results indicate differences in the effects of infarction on these biochemical indices of sympathetic and parasympathetic innervation in canine heart.

A new thermal sensor for surface-based measurement of local myocardial perfusion

1983 ◽  
Vol 244 (3) ◽  
pp. H449-H453
Author(s):  
F. S. Castellana ◽  
R. B. Case ◽  
R. Skalak ◽  
J. M. Cho
Keyword(s):  
Blood Flow ◽  
Coronary Artery ◽  
Reactive Hyperemia ◽  
Coronary Artery Occlusion ◽  
Artery Occlusion ◽  
Tissue Blood Flow ◽  
Thermal Sensor ◽  
Epicardial Surface ◽  
Continuous Surface ◽  
Flow Changes

The transient response of a new thermal sensor for continuous surface-based measurement of local tissue blood flow was evaluated in the beating dog heart. The sensor is 2.5 mm square, tests on the heart, and responds to flow changes only within a region of tissue 3-4 mm below its location on the epicardial surface. Initial studies demonstrate excellent sensitivity, good frequency response with a time constant of the order of 10-11 s, and an ability to continuously monitor changes in local myocardial blood flow during a variety of well-understood interventions, including coronary artery occlusion, reactive hyperemia, and intravenous administration of nitroglycerin and dipyridamole.

Responses to coronary artery occlusion in conscious dogs with selective cardiac denervation

1988 ◽  
Vol 255 (3) ◽  
pp. H525-H533 ◽  
Author(s):  
Y. T. Shen ◽  
D. R. Knight ◽  
S. F. Vatner ◽  
W. C. Randall ◽  
J. X. Thomas
Keyword(s):  
At Risk ◽  
Blood Flow ◽  
Coronary Artery ◽  
Infarct Size ◽  
Coronary Artery Occlusion ◽  
Artery Occlusion ◽  
Conscious Dogs ◽  
Wall Thickening ◽  
Area At Risk ◽  
Cardiac Denervation

The extent to which cardiac denervation alters responses to myocardial ischemia remains controversial. This study compared responses to 24-h coronary artery occlusion (CAO) on measurements of wall thickness (ultrasonic crystals), regional myocardial blood flow (microspheres), and infarct size (triphenyltetrazolium chloride technique) in three groups of conscious dogs with 1) selective posterior left ventricular (LV) wall denervation, 2) selective ventricular denervation, or in 3) intact dogs. After CAO, hemodynamic changes were not different among the three groups. Wall thickening in the ischemic zone became akinetic or paradoxical early after CAO and did not recover in any group over the 24-h monitoring period. Blood flow in the area at risk fell similarly in all groups. Infarct size, as a percentage of the area at risk, was 45 +/- 7% in intact, 48 +/- 6% in posterior LV wall-denervated, and 48 +/- 8% in ventricular-denervated group. There was, however, a lower (P less than 0.05) frequency of arrhythmic beats per minute after 3 h of CAO in the ventricular-denervated group (3.2 +/- 1.4) compared with the intact (11.3 +/- 4.1) or posterior wall-denervated (12.6 +/- 3.2) group. An additional group of ventricular-denervated dogs was studied to determine the effects of sequential, brief 2-min CAO at 2, 4, and 8 wk after denervation. Responses of regional wall thickening to CAO were not affected significantly even after 8 wk following ventricular denervation. Thus, in conscious dogs, neither selective ventricular denervation nor selective denervation of the posterior LV wall improved collateral blood flow, affected regional function favorably, or reduced infarct size after CAO.

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