Molecular and Cellular Mechanisms of Myocardial Stunning

1999 ◽  
Vol 79 (2) ◽  
pp. 609-634 ◽  
Author(s):  
Roberto Bolli ◽  
Eduardo Marbán
Keyword(s):  
Free Radical ◽  
Myocardial Stunning ◽  
Recovery Of Function ◽  
Myocardial Dysfunction ◽  
Calcium Overload ◽  
Global Ischemia ◽  
Stunned Myocardium ◽  
Common Mechanism ◽  
Regional Ischemia

The past two decades have witnessed an explosive growth of knowledge regarding postischemic myocardial dysfunction or myocardial “stunning.” The purpose of this review is to summarize current information regarding the pathophysiology and pathogenesis of this phenomenon. Myocardial stunning should not be regarded as a single entity but rather as a “syndrome” that has been observed in a wide variety of experimental settings, which include the following: 1) stunning after a single, completely reversible episode of regional ischemia in vivo; 2) stunning after multiple, completely reversible episodes of regional ischemia in vivo; 3) stunning after a partly reversible episode of regional ischemia in vivo (subendocardial infarction); 4) stunning after global ischemia in vitro; 5) stunning after global ischemia in vivo; and 6) stunning after exercise-induced ischemia (high-flow ischemia). Whether these settings share a common mechanism is unknown. Although the pathogenesis of myocardial stunning has not been definitively established, the two major hypotheses are that it is caused by the generation of oxygen-derived free radicals (oxyradical hypothesis) and by a transient calcium overload (calcium hypothesis) on reperfusion. The final lesion responsible for the contractile depression appears to be a decreased responsiveness of contractile filaments to calcium. Recent evidence suggests that calcium overload may activate calpains, resulting in selective proteolysis of myofibrils; the time required for resynthesis of damaged proteins would explain in part the delayed recovery of function in stunned myocardium. The oxyradical and calcium hypotheses are not mutually exclusive and are likely to represent different facets of the same pathophysiological cascade. For example, increased free radical formation could cause cellular calcium overload, which would damage the contractile apparatus of the myocytes. Free radical generation could also directly alter contractile filaments in a manner that renders them less responsive to calcium (e.g., oxidation of critical thiol groups). However, it remains unknown whether oxyradicals play a role in all forms of stunning and whether the calcium hypothesis is applicable to stunning in vivo. Nevertheless, it is clear that the lesion responsible for myocardial stunning occurs, at least in part, after reperfusion so that this contractile dysfunction can be viewed, in part, as a form of “reperfusion injury.” An important implication of the phenomenon of myocardial stunning is that so-called chronic hibernation may in fact be the result of repetitive episodes of stunning, which have a cumulative effect and cause protracted postischemic dysfunction. A better understanding of myocardial stunning will expand our knowledge of the pathophysiology of myocardial ischemia and provide a rationale for developing new therapeutic strategies designed to prevent postischemic dysfunction in patients.

Iron-mediated radical reactions upon reperfusion contribute to myocardial "stunning"

1990 ◽  
Vol 259 (6) ◽  
pp. H1901-H1911 ◽  
Author(s):  
R. Bolli ◽  
B. S. Patel ◽  
M. O. Jeroudi ◽  
X. Y. Li ◽  
J. F. Triana ◽  
...  
Keyword(s):  
Free Radical ◽  
Myocardial Stunning ◽  
Time Window ◽  
Contractile Function ◽  
Myocardial Dysfunction ◽  
Venous Blood ◽  
Radical Reactions ◽  
Free Radical Reactions ◽  
Group I

Recent evidence suggests that postischemic myocardial dysfunction ("stunning") is mediated by iron-catalyzed free radical reactions, but the exact time window during which the critical iron-mediated damage develops remains unknown. Furthermore, the evidence that iron promotes free radical reactions in vivo is indirect. Thus open-chest dogs undergoing a 15-min coronary occlusion and 4 h of reperfusion were given one of the following intracoronary infusions: desferrioxamine (DF) beginning 2 min before reperfusion (group I), DF beginning 1 min after reperfusion (group II), iron-loaded DF in dosage identical to group I (group III), or vehicle (controls, group IV). Recovery of contractile function was substantially greater in group I than in controls, whereas in groups II and III it was indistinguishable from controls. To determine whether the protection afforded by DF was due to inhibition of free radical reactions, myocardial production of free radicals was directly assessed by intracoronary infusion of the spin trap alpha-phenyl N-tert-butyl nitrone (PBN). In controls (group VI), radical adducts of PBN were released in the coronary venous blood after reperfusion. DF given as in group I (group V) markedly suppressed myocardial production of PBN adducts. These results strongly suggest that a substantial portion of the damage responsible for myocardial stunning is caused by iron-catalyzed free radical reactions that develop in the initial seconds of reperfusion and can be prevented by administration of iron chelators started just before reflow. Furthermore, the results demonstrate that attenuation of postischemic dysfunction by DF is associated with attenuation of free radical reactions in vivo, thereby providing direct evidence for a pathogenetic role of iron-catalyzed free radical reactions in myocardial stunning in the intact animal.

Evidence for a pathogenetic role of xanthine oxidase in the "stunned" myocardium

1987 ◽  
Vol 252 (3) ◽  
pp. H566-H577 ◽  
Author(s):  
M. I. Charlat ◽  
P. G. O'Neill ◽  
J. M. Egan ◽  
D. R. Abernethy ◽  
L. H. Michael ◽  
...  
Keyword(s):  
Free Radicals ◽  
Xanthine Oxidase ◽  
Myocardial Stunning ◽  
Oxygen Free Radicals ◽  
Contractile Function ◽  
Myocardial Dysfunction ◽  
Stunned Myocardium ◽  
Base Line ◽  
Collateral Flow

Recent evidence suggests that postischemic myocardial dysfunction (or myocardial “stunning”) may be mediated by oxygen free radicals, but the mechanism for their production remains unknown. To explore the role of xanthine oxidase as a potential source of free radicals, open-chest dogs undergoing a 15-min occlusion of the left anterior descending coronary artery (LAD) followed by 4 h of reperfusion (REP) received intravenously either allopurinol (50 mg/kg 48 h, 20 h, and 30 min before occlusion, 10 mg/kg 1 min before REP, and 6.25 mg X kg-1 X h-1 throughout REP, n = 13) or saline (n = 14). The two groups were similar with respect to occluded bed size (postmortem perfusion) and collateral flow (radioactive microspheres). In controls, the transcardiac difference in plasma uric acid (great cardiac vein - arterial concentration) increased 199 +/- 70% (means +/- SE) during ischemia (P less than 0.02) and remained elevated for 5 min after REP; no increase was observed in treated dogs. Regional myocardial function was assessed by measuring systolic wall thickening with an epicardial Doppler probe. The two groups exhibited comparable systolic thickening under base-line conditions and similar degrees of dyskinesis during ischemia. Following REP, however, recovery of contractile function (expressed as percent of preocclusion values) was considerably greater in allopurinol-treated as compared with control dogs: 57 +/- 14 vs. -22 +/- 16 (P less than 0.01) at 1 h, 70 +/- 13 vs. -15 +/- 15 (P less than 0.001) at 2 h, 65 +/- 14 vs. -28 +/- 13 (P less than 0.001) at 3 h, and 68 +/- 13 vs. -17 +/- 14 (P less than 0.001) at 4 h. These differences could not be ascribed to hemodynamic factors. The results suggest that xanthine oxidase is a source of the oxygen free radicals responsible for myocardial stunning following a brief episode of reversible regional ischemia.

Myocardial response to regional ischemia and reperfusion in vivo in rat heart

1993 ◽  
Vol 71 (10-11) ◽  
pp. 811-817 ◽  
Author(s):  
L. L. Ji ◽  
R. G. Fu ◽  
T. G. Waldrop ◽  
K. J. Liu ◽  
H. M. Swartz
Keyword(s):  
Free Radical ◽  
Degradation Products ◽  
Electron Paramagnetic Resonance Spectroscopy ◽  
Ischemia Reperfusion ◽  
High Energy ◽  
Left Ventricular ◽  
Resonance Spectroscopy ◽  
Regional Ischemia ◽  
Nucleotide Degradation

Ischemia–reperfusion-induced myocardial oxidative changes were investigated in open-chest hearts of anesthetized rats. Surgical occlusion of the left anterior descending coronary artery for 30 min followed by 15 min reperfusion resulted in a significant decrease of reduced glutathione, an increase in glutathione disulfide, and an enhanced lipid peroxidation in rapidly frozen left ventricular tissues. Direct electron paramagnetic resonance spectroscopy revealed an increase in free radical concentration in ischemic cardiac tissues reperfused for 45 s, but the increase diminished at 15 min. These alterations were associated with decreased activities of myocardial glutathione peroxidase, glutathione reductase, and catalase. Ischemia resulted in a significant reduction of high-energy phosphate compounds and an accumulation of nucleotide degradation products, particularly adenosine, in the myocardium. Deterioration of cardiovascular function in reperfused animals was also evident. It is concluded that regional ischemia followed by reperfusion in situ can produce biochemical and physiological alterations consistent with free radical injury in rat hearts, and that an increased purine nucleotide degradation and a decreased antioxidant defense may be responsible for the observed changes.Key words: ischemia–reperfusion, myocardium, oxidative damage, glutathione, antioxidant enzyme.

In vivo thiyl free radical formation from hemoglobin following administration of hydroperoxides

1990 ◽  
Vol 277 (2) ◽  
pp. 402-409 ◽  
Author(s):  
Kirk R. Maples ◽  
Christopher H. Kennedy ◽  
Sandra J. Jordan ◽  
Ronald P. Mason
Keyword(s):  
Free Radical ◽  
Radical Formation ◽  
Free Radical Formation

Further studies on free-radical pathology in the major central nervous system disorders: effect of very high doses of methylprednisolone on the functional outcome, morphology, and chemistry of experimental spinal cord impact injury

1982 ◽  
Vol 60 (11) ◽  
pp. 1415-1424 ◽  
Author(s):  
H. B. Demopoulos ◽  
E. S. Flamm ◽  
M. L. Seligman ◽  
D. D. Pietronigro ◽  
J. Tomasula ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Central Nervous System ◽  
Nervous System ◽  
Free Radical ◽  
Tissue Injury ◽  
Functional Restoration ◽  
Radical Reactions ◽  
Free Radical Reactions ◽  
Cord Injury

The hypothesis that pathologic free-radical reactions are initiated and catalyzed in the major central nervous system (CNS) disorders has been further supported by the current acute spinal cord injury work that has demonstrated the appearance of specific, cholesterol free-radical oxidation products. The significance of these products is suggested by the fact that: (i) they increase with time after injury; (ii) their production is curtailed with a steroidal antioxidant; (iii) high antioxidant doses of the steroidal antioxidant which curtail the development of free-radical product prevent tissue degeneration and permit functional restoration. The role of pathologic free-radical reactions is also inferred from the loss of ascorbic acid, a principal CNS antioxidant, and of extractable cholesterol. These losses are also prevented by the steroidal antioxidant. This model system is among others in the CNS which offer distinctive opportunities to study, in vivo, the onset and progression of membrane damaging free-radical reactions within well-defined parameters of time, extent of tissue injury, correlation with changes in membrane enzymes, and correlation with readily measurable in vivo functions.

scholarly journals Free radical-induced generation of isoprostanes in vivo. Evidence for the formation of D-ring and E-ring isoprostanes.

1994 ◽  
Vol 269 (6) ◽  
pp. 4317-4326
Author(s):  
J.D. Morrow ◽  
T.A. Minton ◽  
C.R. Mukundan ◽  
M.D. Campbell ◽  
W.E. Zackert ◽  
...  
Keyword(s):  
Free Radical

Mechanical Unloading Properties of Axial Flow Pumps and their Effect on Myocardial Stunning

1995 ◽  
Vol 18 (12) ◽  
pp. 766-771 ◽  
Author(s):  
F. R. Waldenberger ◽  
B. Meyns ◽  
P. Wouters ◽  
E. De Ruyter ◽  
E. Pongo ◽  
...  
Keyword(s):  
Coronary Artery ◽  
Myocardial Stunning ◽  
Myocardial Dysfunction ◽  
Axial Flow ◽  
Coronary Artery Occlusion ◽  
Artery Occlusion ◽  
Wall Thickening ◽  
Myocardial Wall Motion ◽  
Mechanical Unloading ◽  
Artery Disease

Postischemic myocardial dysfunction affects morbidity and mortality in patients with coronary artery disease. It is known that mechanical unloading of the left heart ventricle can positively influence postischemic myocardial dysfunction. In this respect we tested two miniaturised axial flow pumps, i.e. the 14-F and the 21-F Hemopump®. An experimental study was carried out on 30 open chest sheep where regional myocardial wall motion was followed using sonomicrometry in a preparation of transient coronary artery occlusion. Only the larger 21-F Hemopump® showed hemodynamically significant unloading of the left ventricle. Furthermore, as far as stunning is concerned, systolic wall thickening recovered better when this type of pump was used during reperfusion. Also postejection thickening, which is an indication of diastolic postischemic dysfunction, is reduced significantly in the postischemic area (ANOVA, p<0.05). Thus, the 21F Hemopump®, but not the 14F Hemopump®, provides adequate mechanical unloading in order to beneficially influence myocardial stunning.

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