Characteristics of regional myocardial stunning after exercise in dogs with chronic coronary stenosis

1989 ◽  
Vol 257 (1) ◽  
pp. H113-H119 ◽  
Author(s):  
E. Thaulow ◽  
B. D. Guth ◽  
G. Heusch ◽  
E. Gilpin ◽  
R. Schulz ◽  
...  
Keyword(s):  
Blood Flow ◽  
Coronary Stenosis ◽  
Myocardial Stunning ◽  
Wall Thickening ◽  
Regional Ischemia ◽  
Ischemic Region ◽  
Regional Dysfunction ◽  
Exercise Induced ◽  
Systolic Wall Thickening ◽  
Chronically Instrumented Dogs

Persistent impairment of regional contraction of the left ventricle after restoration of blood flow following transient coronary occlusion has been termed “stunning,” and reversible regional dysfunction has also been observed during recovery from exercise-induced regional ischemia. To determine whether limitation of subendocardial blood flow after exercise is a determinant of such dysfunction in the presence of chronic coronary stenosis, nine conscious chronically instrumented dogs having an Ameroid constrictor were studied before, during, and after treadmill runs that induced regional ischemia. During exercise, systolic wall thickening (%WTh, sonomicrometers) in the ischemic region decreased from a normal level of 22.1 +/- 9.1% at rest to 8.8 +/- 5.2% (+/- SD, P less than 0.01), whereas subendocardial blood flow (microspheres) in the ischemic region decreased from 0.75 +/- 0.25 to 0.45 +/- 0.27 ml.min-1.g-1 (P less than 0.05). %WTh in the ischemic region gradually improved after exercise but remained depressed (75% of control) at 30 min after the run (P less than 0.05). Postexercise dysfunction was not related to simultaneous regional hypoperfusion, since at 5 and 10 min after running there was a tendency toward subendocardial hyperemia (control 0.75 vs. 1.33 and 1.30 ml.min-1.g-1, NS) with a return to control by 30 min. Thus persistent regional dysfunction after exercise-induced regional ischemia in the conscious dog is not due to sustained subendocardial ischemia in the presence of chronic coronary stenosis and represents an example of myocardial stunning.

Cumulative deterioration of myocardial function after repeated episodes of exercise-induced ischemia

1989 ◽  
Vol 256 (5) ◽  
pp. H1462-H1471 ◽  
Author(s):  
D. C. Homans ◽  
D. D. Laxson ◽  
E. Sublett ◽  
P. Lindstrom ◽  
R. J. Bache
Keyword(s):  
Blood Flow ◽  
Coronary Artery ◽  
Coronary Stenosis ◽  
Myocardial Dysfunction ◽  
Wall Thickening ◽  
The Third ◽  
Single Period ◽  
Exercise Period ◽  
Exercise Induced ◽  
Systolic Wall Thickening

To determine whether progressive regional myocardial dysfunction occurs after repetitive episodes of exercise-induced ischemia, 10 dogs were instrumented with ultrasonic microcrystals for determination of regional myocardial wall thickening, circumflex artery electromagnetic flow probes, and hydraulic coronary artery occluders. Dogs performed treadmill exercise in the presence of a coronary artery stenosis, which limited coronary blood flow to control levels. Dogs performed a single 10-min exercise period one day and three identical runs separated by 1-h rest periods on the alternate day. At rest before the first exercise period, circumflex wall thickening was 18.8 +/- 6.7% and increased to 25.5 +/- 10.6% during exercise before the application of coronary stenosis. On the day that three exercise trials were performed, circumflex systolic wall thickening at rest before the third exercise period (9.7 +/- 4.0%) and during exercise without coronary stenosis (17.3 +/- 7.3%) were both significantly lower than during the first exercise period (P less than 0.0125). During exercise with stenosis, circumflex systolic wall thickening fell to 4.6 +/- 4.7% during a single run, and 5.0 +/- 2.0% during the third of three consecutive runs. Wall thickening was significantly lower 2 h after the third consecutive run (9.1 +/- 2.4%) than 2 h after a single period of exercise-induced ischemia (14.8 +/- 7.6%; P 0.0125). Transmural myocardial blood flow to circumflex myocardium during the third period of exercise-induced ischemia (0.93 +/- 0.47 ml.min-1.g-1) was not different than during the single period of exercise (0.84 +/- 0.47 ml.min-1.g-1). It is concluded that repetitive episodes of exercise-induced ischemia result in cumulative postexercise regional myocardial dysfunction.

Differences in myocardial stunning following coronary artery occlusion in conscious dogs, pigs, and baboons

1996 ◽  
Vol 270 (4) ◽  
pp. H1312-H1322 ◽  
Author(s):  
Y. T. Shen ◽  
S. F. Vatner
Keyword(s):  
Blood Flow ◽  
Coronary Artery ◽  
Myocardial Stunning ◽  
Coronary Artery Occlusion ◽  
Artery Occlusion ◽  
Conscious Dogs ◽  
Wall Thickening ◽  
Systolic Wall Thickening

To determine whether myocardial stunning differs among dogs, pigs, and baboons and is reproducible within species, we examined the effects of 10-min coronary artery (CA) occlusion (CAO) on 9 conscious dogs, 12 minipigs, and 6 baboons. During 10-min CAO, systolic wall thickening in the ischemic zone fell similarly in dogs (-108 +/- 5.6%), pigs (-102 +/- 1.8%), and baboons (-107 +/- 5.7%), but blood flow fell more (P < 0.05) in the subepicardium in pigs (0.07 +/- 0.01 ml.min-1.g-1) and baboons (0.07 +/- 0.02 ml.min-1.g-1) than in dogs (0.18 +/- 0.03 ml.min-1.g-1). At 1 h after CA reperfusion (CAR), wall thickening was reduced more (P < 0.05) in dogs (-40 +/- 4.2%) than in pigs (-22 +/- 2.1%) and baboons (-4 +/- 2.4%). In five dogs and five pigs, three separate 10-min CAO, each 2 days apart, were also examined. In dogs, reductions in wall thickening after CAR were significantly less following the second (-26 +/- 4.2%) or third (-30 +/- 3.2%) CAO, compared with the first CAO (-47 +/- 4.9%). In contrast, repetitive CAO did not induce differences in recovery of wall thickening in pigs. These results indicate that myocardial stunning is less severe in conscious pigs and baboons, compared with conscious dogs, despite more intense transmural ischemia. The dogs demonstrated a "preconditioning-like effect" with serial brief CAO, which was not exhibited in pigs.

Myocardial stunning in exercise-induced ischemia in dogs: lack of late preconditioning

2001 ◽  
Vol 280 (1) ◽  
pp. H302-H310 ◽  
Author(s):  
Olivier Parent De Curzon ◽  
Bijan Ghaleh ◽  
Renaud Tissier ◽  
Jean-François Giudicelli ◽  
Luc Hittinger ◽  
...  
Keyword(s):  
Blood Flow ◽  
Coronary Artery ◽  
Myocardial Stunning ◽  
Time Course ◽  
Reactive Hyperemia ◽  
Coronary Artery Occlusion ◽  
Left Ventricular ◽  
Wall Thickening ◽  
Late Preconditioning ◽  
Exercise Induced

Late preconditioning (PC) against myocardial stunning develops after coronary artery occlusion (CAO) at rest and subsequent reperfusion. We investigated whether late PC occurs after exercise-induced ischemia (high-flow ischemia) in dogs. A circumflex coronary artery stenosis (by using occluders) was set up before the onset of treadmill exercise in nine chronically instrumented dogs to suppress exercise-induced increase in mean coronary blood flow velocity (CBFV, Doppler) without simultaneously affecting left ventricular (LV) wall thickening (Wth) at rest. Two similar exercises were performed 24 h apart. On day 1, LV Wth was reduced by 84 ± 5% ( P < 0.01), and exercise-induced increases in transmural myocardial blood flow (MBF, fluorescent microspheres) in the ischemic zone were blunted. LV Wth was depressed throughout the first 10 h and returned to its baseline value after 24 h. On day 2, changes in LV Wth and MBF were similar as was the time course for LV Wth recovery, indicating lack of late PC. Also, CBFV responses to acetylcholine, nitroglycerin, and reactive hyperemia (20-s CAO) were not significantly different on days 1 and 2. Similar results were obtained in a subgroup of four additional dogs with more severe stenosis during exercise. Late PC against myocardial stunning was confirmed to occur in a model of 10-min CAO followed by coronary artery reperfusion (CAR) in another four dogs. Thus in contrast with CAO at rest followed by CAR, severe myocardial ischemia in coronary flow-limited exercising dogs does not induce late PC against myocardial stunning.

Effects of beta-blockade on regional myocardial flow and function during exercise

1984 ◽  
Vol 247 (1) ◽  
pp. H52-H60 ◽  
Author(s):  
M. Matsuzaki ◽  
J. Patritti ◽  
T. Tajimi ◽  
M. Miller ◽  
W. S. Kemper ◽  
...  
Keyword(s):  
Coronary Artery ◽  
Myocardial Dysfunction ◽  
Left Ventricular Pressure ◽  
Left Ventricular ◽  
Beta Blockade ◽  
Wall Thickening ◽  
Ischemic Area ◽  
Ischemic Region ◽  
Exercise Induced ◽  
Control Exercise

We examined the effects of a cardioselective beta-blocking drug on exercise-induced regional myocardial ischemia in 10 conscious dogs with chronic coronary artery stenosis. An ameroid constrictor, Doppler flowprobe, and hydraulic cuff were placed around the left circumflex coronary artery, and left ventricular pressure (LVP), systolic wall thickening (% delta WT; by sonomicrometry), and myocardial blood flow (MBF; microspheres) were measured during control standing, control treadmill exercise, and identical exercise after atenolol (1 mg/kg po). Prior to study, in every dog % delta WT and MBF in the ischemic area were normal at rest, indicating collateral development. During control exercise, % delta WT in the ischemic region markedly decreased from 27 to 4%, and transmural ischemia was evident in that region. Heart rate, systolic LVP, and LV (+)dP/dt were significantly lower during exercise after atenolol than during control exercise. % delta WT in the normal area was only 81% of that during control exercise, but dysfunction in the ischemic area was improved (77% increase compared with control exercise). Accompanying the improved function was a significant increase of MBF/beat and relative MBF in the ischemic zone; the endocardial-to-epicardial ratio increased from 0.27 to 0.47. Thus atenolol improved regional MBF distribution, thereby diminishing exercise-induced regional myocardial dysfunction and accelerating its recovery.

Myocardial blood flow and function with critical coronary stenosis in exercising dogs

1982 ◽  
Vol 243 (5) ◽  
pp. H698-H707 ◽  
Author(s):  
K. P. Gallagher ◽  
G. Osakada ◽  
M. Matsuzaki ◽  
W. S. Kemper ◽  
J. Ross
Keyword(s):  
Blood Flow ◽  
Myocardial Blood Flow ◽  
Wall Thickening ◽  
Critical Stenosis ◽  
Vasodilator Reserve ◽  
Primary Determinant ◽  
And Function ◽  
Systolic Wall Thickening ◽  
Coronary Blood Flow Velocity ◽  
Contractile Performance

Critical stenosis of coronary arteries does not alter myocardial blood flow (MBF) at rest, but eliminates hyperemia and corresponds to a degree of arterial narrowing that expends subendocardial vasodilator reserve. Because subepicardial vasodilator reserve remains with critical stenosis at rest, we tested the significance of this reserve in six exercising dogs chronically instrumented to measure MBF (microspheres), regional function (systolic wall thickening with sonomicrometers), and coronary blood flow velocity (CBFV, pulsed Doppler). Critical stenosis produced with a hydraulic occluder limited CBFV and mean MBF to the resting level during treadmill exercise, but MBF was maldistributed. Subendocardial MBF decreased 50% (P less than 0.05) and subepicardial MBF increased 104% (P less than 0.01) compared with resting control conditions, suggesting that a transmural "steal" phenomenon had occurred, with augmented MBF in the subepicardial region at the expense of subendocardial MBF. Systolic wall thickening decreased markedly from 31.5 +/- 6.8 to 9.4 +/- 2.0% (P less than 0.01) during exercise, indicating that use of subepicardial vasodilator reserve with critical stenosis had little sustaining effect on regional contractile performance. Rather, subepicardial vasodilator reserve is potentially deleterious, inasmuch as a steal effect could contribute to reduced subendocardial perfusion, the primary determinant of systolic wall thickening.

Placental growth factor increases regional myocardial blood flow and contractile function in chronic myocardial ischemia

2013 ◽  
Vol 304 (6) ◽  
pp. H885-H894 ◽  
Author(s):  
Xiaoshun Liu ◽  
Piet Claus ◽  
Ming Wu ◽  
Geert Reyns ◽  
Peter Verhamme ◽  
...  
Keyword(s):  
Blood Flow ◽  
Growth Factor ◽  
Myocardial Perfusion ◽  
Contractile Function ◽  
Placental Growth Factor ◽  
Regional Myocardial Blood Flow ◽  
Wall Thickening ◽  
Systolic Wall Thickening ◽  
Regional Myocardial Blood ◽  
Chronic Myocardial Ischemia

Placental growth factor (PlGF) has a distinct biological phenotype with a predominant proangiogenic role in disease without affecting quiescent vessels in healthy organs. We tested whether systemic administration of recombinant human (rh)PlGF improves regional myocardial blood flow (MBF) and systolic function recovery in a porcine chronic myocardial ischemia model. We implanted a flow-limiting stent in the proximal left anterior descending coronary artery and measured systemic hemodynamics, regional myocardial function using MRI, and blood flow using colored microspheres 4 wk later. Animals were then randomized in a blinded way to receive an infusion of rhPlGF (15 μg·kg−1·day−1, n = 9) or PBS (control; n = 10) for 2 wk. At 8 wk, myocardial perfusion and function were reassessed. Infusion of rhPlGF transiently increased PlGF serum levels >30-fold (1,153 ± 180 vs. 33 ± 18 pg/ml at baseline, P < 0.001) without affecting systemic hemodynamics. From 4 to 8 wk, rhPlGF increased regional MBF from 0.46 ± 0.11 to 0.85 ± 0.16 ml·min−1·g−1, with a concomitant increase in systolic wall thickening from 11 ± 3% to 26 ± 5% in the ischemic area. In control animals, no significant changes from 4 to 8 wk were observed (MBF: 0.45 ± 0.07 to 0.49 ± 0.08 ml·min−1·g−1 and systolic wall thickening: 14 ± 4% to 18 ± 1%). rhPlGF-induced functional improvement was accompanied by increased myocardial neovascularization, enhanced glycogen utilization, and reduced oxidative stress and cardiomyocyte apoptosis in the ischemic zone. In conclusion, systemic rhPlGF infusion significantly enhances regional blood flow and contractile function of the chronic ischemic myocardium without adverse effects. PlGF protein infusion may represent an attractive therapeutic strategy to increase myocardial perfusion and energetics in chronic ischemic cardiomyopathy.

Coronary hyperperfusion augments myocardial oxygen consumption

1996 ◽  
Vol 271 (4) ◽  
pp. H1384-H1393 ◽  
Author(s):  
Y. Ishibashi ◽  
J. Zhang ◽  
D. J. Duncker ◽  
C. Klassen ◽  
T. Pavek ◽  
...  
Keyword(s):  
Blood Flow ◽  
Oxygen Consumption ◽  
Coronary Blood Flow ◽  
Myocardial Oxygen Consumption ◽  
Contractile Function ◽  
Left Ventricular ◽  
Wall Thickening ◽  
Systolic Thickening ◽  
Subepicardial Layer ◽  
Systolic Wall Thickening

This study was performed to test the hypothesis that increases in myocardial oxygen consumption (MVo2) and myocardial contractile function during exercise are flow limited. Studies were performed in 15 chronically instrumented normal dogs. MVo2 and regional percent systolic wall thickening were measured during control conditions and during maximal vasodilation produced by infusion of adenosine (20-75 micrograms.kg-1.min-1) or adenosine combined with nitroglycerin (0.4 micrograms.kg-1.min-1; TNG) into the left anterior descending coronary artery during a three-stage graded treadmill exercise protocol. Adenosine and adenosine plus TNG significantly increased coronary blood flow by 298 +/- 26 and 306 +/- 24%, respectively, at rest and by 134 +/- 7 and 145 +/- 9%, respectively, during the heaviest level of exercise (each P < 0.01). Adenosine and adenosine plus TNG increased MVo2 at rest, but this was associated with a parallel increase in heart rate, so that MVo2 per beat was not significantly changed. Systolic wall thickening was also not changed by hyperperfusion during resting conditions. However, MVo2 per beat was increased by 12 +/- 4% with adenosine and by 13 +/- 5% with adenosine plus TNG during moderate exercise and by 23 +/- 5% with adenosine and by 27 +/- 4% with adenosine plus TNG during the heaviest level of exercise (each P < 0.05). Systolic thickening of the full left ventricular wall did not change during hyperperfusion, but thickening in the subepicardial layer was increased by 14 +/- 3% with adenosine and 18 +/- 3% with adenosine plus TNG during the heaviest level of exercise (each P < 0.05). There was no difference in wall thickening between adenosine and adenosine plus TNG. These findings imply that the increases in MVo2 which occur during exercise are limited by coronary blood flow.

Depression of regional blood flow and wall thickening after brief coronary occlusions

1978 ◽  
Vol 234 (6) ◽  
pp. H653-H659 ◽  
Author(s):  
G. R. Heyndrickx ◽  
H. Baig ◽  
P. Nellens ◽  
I. Leusen ◽  
M. C. Fishbein ◽  
...  
Keyword(s):  
Blood Flow ◽  
Myocardial Blood Flow ◽  
Coronary Occlusion ◽  
Reactive Hyperemia ◽  
Left Ventricular ◽  
Regional Myocardial Blood Flow ◽  
Wall Thickening ◽  
Flow Ratio ◽  
Systolic Wall Thickening ◽  
Regional Myocardial Blood

The effects of a 15-min coronary occlusion and subsequent reperfusion were investigated in conscious dogs previously instrumented for measurement of left ventricular pressure, dP/dt, regional wall thickening, electrograms, and myocardial blood flow. Coronary occlussion reduced overall left ventricular function only slightly but eliminated systolic wall thickening in the ischemic zone and reduced regional myocardial blood flow in the ischemic zone from 1.04 +/- 0.04 to 0.27 +/- 0.02 ml/min per g and the endo/epi flow ratio from 1.23 +/- 0.04 to 0.44 +/- 0.04, while S-T segment elevation increased from 1.1 +/- 0.3 to 8.2 +/- 0.9 mV. After release of the occlusion, S-T segment elevation disappeared within 1 min while reactive hyperemia in the previously occluded artery and a transient increase in cardiac diastolic wall thickness occurred and then subsided by 15 min. In contrast, systolic wall thickening and the endo/epi flow ratio remained significantly depressed for more than 3 h. Thus reperfusion after a 15 minute coronary occlusion results in a prolonged period of reduced regional myocardial blood flow, particularly in the endocardial layers, which correlates with the prolonged depression of regional myocardial shortening and wall thickening.

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