Effects of exercise on collateral development in myocardial ischemia in pigs

1984 ◽  
Vol 56 (3) ◽  
pp. 656-665 ◽  
Author(s):  
C. M. Bloor ◽  
F. C. White ◽  
T. M. Sanders
Keyword(s):  
Coronary Artery ◽  
Myocardial Ischemia ◽  
Exercise Training ◽  
Collateral Circulation ◽  
Coronary Artery Stenosis ◽  
Arterial Stenosis ◽  
Collateral Flow ◽  
Circumflex Coronary Artery ◽  
Complete Occlusion ◽  
Collateral Development

To study the effects of exercise on collateral development in myocardial ischemia, we induced coronary arterial stenosis of the left circumflex coronary artery (LCCA) in 18 of 30 pigs. During that surgery, we identified the coronary bed at risk. Nine of these pigs were then subjected to 5 mo of exercise training on a treadmill. After exercise training, we determined regional collateral and myocardial blood flow using radiolabeled microspheres. At autopsy, all animals had complete occlusion of the LCCA. Infarct size in the exercise-trained pigs was significantly less than in the sedentary pigs (5.9 +/- 1.0 vs. 11.7 +/- 1.0% of the left ventricle). The exercise-trained animals had a greater increase in collateral flow, 35.1 +/- 3.0 vs. 28.7 +/- 4.1 ml X min-1 X 100 g-1, in the noninfarcted jeopardized zone of the LCCA bed. The major findings of the study were the following: 1) chronic coronary artery stenosis progressing to occlusion stimulated development of the collateral circulation and salvaged tissue in the jeopardized myocardium of an animal model with sparse collaterals; 2) development of the collateral circulation and tissue salvage is increased by exercise training; 3) collaterals develop primarily in or near the ischemic zone; and 4) all collateral beds develop a circumferential flow gradient following occlusion.

Collateral circulation after coronary artery constriction

1965 ◽  
Vol 208 (1) ◽  
pp. 144-148 ◽  
Author(s):  
Matthew N. Levy ◽  
Moris Chansky
Keyword(s):  
Coronary Artery ◽  
Collateral Circulation ◽  
Ventricular Myocardium ◽  
Collateral Flow ◽  
Vascular Tree ◽  
Circumflex Coronary Artery ◽  
Ischemic Region ◽  
Threefold Increase ◽  
Collateral Vessels ◽  
Marginal Zones

The extent and distribution of the collateral circulation to the ventricular myocardium which develops after partial constriction of the left circumflex coronary artery for 1 week were investigated by means of the Rb86-clearance technic. Interarterial communications were distinguished from anastomoses occurring at lower levels of the vascular tree by comparing the Rb86 clearances obtained while the retrograde-flow tubing was clamped with clearances obtained while the tubing was patent. In the central region of the ischemic myocardium, there was a two- to threefold increase in the total collateral flow after coronary artery narrowing. The collateral vessels to this region were predominantly interarterial communications. The data suggested, however, that non-interarterial anastomoses to the central zones must also have proliferated. In the marginal zones of the ischemic region, the predominant communications were non-interarterial.

Abstract 2941: Combined Assessment of Coronary Artery Stenosis and Myocardial Ischemia by Rest-Dipyridamole Stress Multidetector Computed Tomography

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Patricia M Carrascosa ◽  
Carlos Capuñay ◽  
Jorge Carrascosa ◽  
Alejandro Deviggiano ◽  
Alejandro Goldsmit ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Coronary Artery Disease ◽  
Coronary Artery ◽  
Myocardial Ischemia ◽  
Contrast Enhancement ◽  
Coronary Artery Stenosis ◽  
Artery Stenosis ◽  
Artery Disease ◽  
Mdct Coronary Angiography ◽  
Dipyridamole Stress

Introduction: MDCT coronary angiography has been evolving as a noninvasive method for the assessment of coronary artery disease (CAD). More recently, It has been demonstrated that MDCT identifies reduced contrast enhancement in ischemic and/or scarred myocardial segments. Objective: to determine the ability of rest-stress multidetector computed tomography (RS-MDCT) to detect myocardial ischemia and to assess the relationship between MDCT myocardial perfusion abnormalities and coronary artery stenosis. Methods: Forty seven patients underwent stress/rest 99mTc sestamibi SPECT and RS-MDCT, using a 16-row detector scanner (Philips Brilliance-16). Myocardial segments were classified by SPECT as normal, ischemic or scarred. SPECT results were then compared with MDCT regional myocardial contrast enhancement. The results of MDCT coronary angiography were also analyzed in 20 patients who underwent invasive catheterization. Results: The presence of a reduction in contrast enhancement at rest by MDCT identified scar by SPECT with 96% sensitivity and 98% specificity. A stress-induced reduction in contrast enhancement by MDCT identified ischemia by SPECT with 77% sensitivity and 99% specificity. The segment-based sensitivity and specificity for the detection of significant stenosis by MDCT were 92% and 98%, respectively. Conclusion: Our results showed that a rest-dipyridamole stress MDCT protocol can identify the presence of myocardial ischemia as well as the severity of coronary artery stenosis in patients with suspected coronary artery disease.

Functional anatomical site of intramural collaterals in dogs

1990 ◽  
Vol 259 (3) ◽  
pp. H706-H711 ◽  
Author(s):  
K. W. Scheel ◽  
G. Daulat ◽  
S. E. Williams
Keyword(s):  
Coronary Artery ◽  
Flow Measurement ◽  
Isolated Heart ◽  
Anatomical Site ◽  
Collateral Flow ◽  
Retrograde Flow ◽  
Circumflex Coronary Artery ◽  
Dog Heart ◽  
Before And After ◽  
Collateral Vessels

The objectives of the present study were to determine quantitatively whether the retrograde flow measurement reflects the total flow from collateral vessels or overestimates or underestimates collateral flow, and to determine the functional anatomical origin of intramural collaterals in the native dog heart. In an isolated heart preparation, three experimental procedures were used. 1) The left circumflex coronary artery was embolized with microspheres of different sizes; then retrograde flows and the peripheral coronary pressures were measured. 2) Epicardial collaterals were cauterized, and retrograde flows were measured before and after cautery. 3) Epicardial collaterals were cauterized followed by embolization of the circumflex coronary artery with different size spheres. We found that 1) the retrograde flow measurement underestimates the total collateral flow to the circumflex coronary artery by approximately 25%, 2) intramural collateral flow constitutes 58 +/- 3.5% of the retrograde flow measurement, 3) the antegrade component of blood flow that is not measured during a retrograde flow measurement is from the intramural collateral circulation, and 4) the functional site of origin of intramural collaterals is greater than 25 microns but less than 80 microns in diameter. We conclude that, in our preparation, retrograde flow underestimates total collateral flow, and that intramural collateral flow is a major component of retrograde flow in the native dog heart.

Inhibition of adenosine-mediated coronary vasodilation exacerbates myocardial ischemia during exercise

1993 ◽  
Vol 265 (5) ◽  
pp. H1471-H1477 ◽  
Author(s):  
D. D. Laxson ◽  
D. C. Homans ◽  
R. J. Bache
Keyword(s):  
Blood Flow ◽  
Coronary Artery ◽  
Myocardial Ischemia ◽  
Myocardial Blood Flow ◽  
Coronary Perfusion Pressure ◽  
Coronary Perfusion ◽  
Coronary Vasodilation ◽  
Circumflex Coronary Artery ◽  
Left Circumflex Coronary Artery ◽  
Transmural Flow

Persisting coronary vasoconstrictor tone that is responsive to exogenous adenosine administration has been demonstrated during myocardial ischemia. Therefore, the role and extent of endogenous adenosine-mediated coronary vasodilation in opposing coronary vasoconstriction within regions of ischemic myocardium was investigated in 10 chronically instrumented exercising dogs. Studies were performed on dogs with left circumflex coronary artery stenosis during treadmill exercise (6.5 km/h, 6% grade), while myocardial blood flow was measured with radioactive microspheres. Blood flow was measured before and again after inhibition of the effects of endogenously produced adenosine through combined inactivation of adenosine and adenosine receptor antagonism by the administration of intracoronary adenosine deaminase (ADA) (5 micrograms.kg-1 x min-1 x 10 min) plus 8-phenyltheophylline (8-PT) (5 mg/kg i.v.), respectively. Coronary perfusion pressure was held equal during both conditions at approximately 41 mmHg with a hydraulic occluder. During exercise in the presence of a coronary stenosis, blood flow was reduced in all layers of myocardium in regions supplied by the stenosed left circumflex coronary artery compared with blood flow in regions of myocardium supplied by the nonstenotic left anterior descending coronary artery. After ADA plus 8-PT, myocardial blood flow (in ml.min-1 x g-1) was further reduced in all layers of myocardium in regions supplied by the stenotic left circumflex coronary artery compared with baseline (subendocardial layer 0.44 +/- 0.09 vs. 0.67 +/- 0.13 ml.min-1 x g-1, mean transmural flow 0.92 +/- 0.13 vs. 1.25 +/- 0.2 ml.min-1 x g-1, both P < 0.05). Blood flow in regions of myocardium supplied by the nonstenotic left anterior descending coronary artery were unchanged following ADA plus 8-PT.(ABSTRACT TRUNCATED AT 250 WORDS)

Exercise training restores adenosine-induced relaxation in coronary arteries distal to chronic occlusion

2000 ◽  
Vol 278 (6) ◽  
pp. H1984-H1992 ◽  
Author(s):  
Cristine L. Heaps ◽  
Michael Sturek ◽  
Julie A. Rapps ◽  
M. Harold Laughlin ◽  
Janet L. Parker
Keyword(s):  
Coronary Artery ◽  
Exercise Training ◽  
Sodium Nitroprusside ◽  
Coronary Arteries ◽  
Coronary Occlusion ◽  
Circumflex Coronary Artery ◽  
Miniature Swine ◽  
Chronic Occlusion ◽  
Chronic Coronary Occlusion ◽  
Camp And Cgmp

We previously reported that canine collateral-dependent coronary arteries exhibit impaired relaxation to adenosine but not sodium nitroprusside. In contrast, exercise training enhances adenosine sensitivity of normal porcine coronary arteries. These results stimulated the hypothesis that chronic coronary occlusion and exercise training produce differential effects on cAMP- versus cGMP-mediated relaxation. To test this hypothesis, Ameroid occluders were surgically placed around the proximal left circumflex coronary artery (LCx) of female Yucatan miniature swine 8 wk before initiating sedentary or exercise training (treadmill run, 16 wk) protocols. Relaxation to the cAMP-dependent vasodilators adenosine (10− 7 to 10− 3 M) and isoproterenol (3 × 10− 8 to 3 × 10− 5 M) were impaired in collateral-dependent LCx versus nonoccluded left anterior descending (LAD) arterial rings isolated from sedentary but not exercise-trained pigs. Furthermore, adenosine-mediated reductions in simultaneous tension and myoplasmic free Ca2+ were impaired in LCx versus LAD arteries isolated from sedentary but not exercise-trained pigs. In contrast, relaxation in response to the cAMP-dependent vasodilator forskolin (10− 9 to 10− 5 M) and the cGMP-dependent vasodilator sodium nitroprusside (10− 9 to 10− 4 M) was not different in LCx versus LAD arteries of sedentary or exercise-trained animals. These data suggest that chronic occlusion impairs receptor-dependent, cAMP-mediated relaxation; receptor-independent cAMP- and cGMP-mediated relaxation were unimpaired. Importantly, exercise training restores cAMP-mediated relaxation of collateral-dependent coronary arteries.

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