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Henry Gewirtz, MD (1945-2021). J Nucl Cardiol 2021. [PMID: 33982203 DOI: 10.1007/s12350-021-02657-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Dilsizian V. Interpretation and clinical management of patients with "Fixed" myocardial perfusion defects : A call for quantifying endocardial-to-epicardial distribution of blood flow. J Nucl Cardiol 2021; 28:723-728. [PMID: 33415645 DOI: 10.1007/s12350-020-02492-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Accepted: 12/10/2020] [Indexed: 11/24/2022]
Affiliation(s)
- Vasken Dilsizian
- Department of Diagnostic Radiology and Nuclear Medicine, University of Maryland School of Medicine, 22 South Greene Street, Baltimore, MD, 21201, USA.
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From Physiology of the Coronary Circulation to Myocardial Perfusion Imaging. CURRENT CARDIOVASCULAR IMAGING REPORTS 2015. [DOI: 10.1007/s12410-014-9313-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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The in-situ pig heart with regional ischemia/reperfusion — Ready for translation. J Mol Cell Cardiol 2011; 50:951-63. [DOI: 10.1016/j.yjmcc.2011.02.016] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2011] [Revised: 02/22/2011] [Accepted: 02/23/2011] [Indexed: 11/18/2022]
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Cardiac PET: A Versatile, Quantitative Measurement Tool for Heart Failure Management. JACC Cardiovasc Imaging 2011; 4:292-302. [DOI: 10.1016/j.jcmg.2010.12.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Revised: 12/20/2010] [Accepted: 12/23/2010] [Indexed: 11/21/2022]
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Dünser MW, Hasibeder WR. Sympathetic overstimulation during critical illness: adverse effects of adrenergic stress. J Intensive Care Med 2009; 24:293-316. [PMID: 19703817 DOI: 10.1177/0885066609340519] [Citation(s) in RCA: 315] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The term ''adrenergic'' originates from ''adrenaline'' and describes hormones or drugs whose effects are similar to those of epinephrine. Adrenergic stress is mediated by stimulation of adrenergic receptors and activation of post-receptor pathways. Critical illness is a potent stimulus of the sympathetic nervous system. It is undisputable that the adrenergic-driven ''fight-flight response'' is a physiologically meaningful reaction allowing humans to survive during evolution. However, in critical illness an overshooting stimulation of the sympathetic nervous system may well exceed in time and scope its beneficial effects. Comparable to the overwhelming immune response during sepsis, adrenergic stress in critical illness may get out of control and cause adverse effects. Several organ systems may be affected. The heart seems to be most susceptible to sympathetic overstimulation. Detrimental effects include impaired diastolic function, tachycardia and tachyarrhythmia, myocardial ischemia, stunning, apoptosis and necrosis. Adverse catecholamine effects have been observed in other organs such as the lungs (pulmonary edema, elevated pulmonary arterial pressures), the coagulation (hypercoagulability, thrombus formation), gastrointestinal (hypoperfusion, inhibition of peristalsis), endocrinologic (decreased prolactin, thyroid and growth hormone secretion) and immune systems (immunomodulation, stimulation of bacterial growth), and metabolism (increase in cell energy expenditure, hyperglycemia, catabolism, lipolysis, hyperlactatemia, electrolyte changes), bone marrow (anemia), and skeletal muscles (apoptosis). Potential therapeutic options to reduce excessive adrenergic stress comprise temperature and heart rate control, adequate use of sedative/analgesic drugs, and aiming for reasonable cardiovascular targets, adequate fluid therapy, use of levosimendan, hydrocortisone or supplementary arginine vasopressin.
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Affiliation(s)
- Martin W Dünser
- Department of Anaesthesiology and Critical Care Medicine, Innsbruck Medical University, Anichstrasse, Innsbruck, Austria.
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Gewirtz H, Tawakol A, Bacharach SL. Heterogeneity of myocardial blood flow and metabolism: review of physiologic principles and implications for radionuclide imaging of the heart. J Nucl Cardiol 2002; 9:534-41. [PMID: 12360134 DOI: 10.1067/mnc.2002.125916] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Henry Gewirtz
- Department of Medicine, Cardiac Unit, Massachusetts General Hospital, Boston 02114, USA.
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Pelberg RA, Spotnitz WD, Bin JP, Le E, Goodman NC, Kaul S. Mechanism of myocardial dysfunction in the presence of chronic coronary stenosis and normal resting myocardial blood flow: clinical implications. J Am Soc Echocardiogr 2001; 14:1047-56. [PMID: 11696827 DOI: 10.1067/mje.2001.113232] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In chronic coronary artery disease, resting myocardial dysfunction can exist despite normal resting transmural myocardial blood flow (MBF). We hypothesized that this phenomenon occurs because of diminished endocardial MBF reserve. MBF (measured with radiolabeled microspheres) and wall thickening (WT) (measured with echocardiography) were assessed in 7 dogs after the development of severe left ventricular dysfunction caused by placement of ameroid constrictors on the left anterior descending (LAD) and left circumflex arteries and 3 weeks after selective bypass surgery to the LAD. Before surgery, the mean transmural MBF at rest and at peak dobutamine dose in the LAD bed were 1.1 +/- 0.5 and 3.0 +/- 1.5 mL/min per gram, respectively, and were not significantly changed after LAD bypass. The resting endocardial-to-epicardial MBF ratio (EER) was also normal before bypass (1.5 +/- 0.6) and remained unchanged after surgery. The prebypass EER at peak dobutamine dose, however, was markedly diminished in the LAD bed (0.7 +/- 0.3) and improved significantly (1.3 +/- 0.8, P <.01) after surgery. Resting WT in the LAD bed also improved to normal levels (36% +/- 4% versus 13% +/- 6%, P =.0001) and no longer demonstrated a biphasic response to dobutamine. In comparison, the nonbypassed left circumflex bed continued to show reduced resting WT (12% +/- 6%), a biphasic response to dobutamine, and abnormal EER during rest and dobutamine (0.7 +/- 0.3). We conclude that persistent myocardial dysfunction in the presence of normal resting transmural MBF can occur as a result of diminished endocardial MBF reserve, with transmural MBF reserve remaining normal.
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Affiliation(s)
- R A Pelberg
- Cardiac Imaging Center, Cardiovascular Division, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
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Landesberg G, Mosseri M, Zahger D, Wolf Y, Perouansky M, Anner H, Drenger B, Hasin Y, Berlatzky Y, Weissman C. Myocardial infarction after vascular surgery: the role of prolonged stress-induced, ST depression-type ischemia. J Am Coll Cardiol 2001; 37:1839-45. [PMID: 11401120 DOI: 10.1016/s0735-1097(01)01265-7] [Citation(s) in RCA: 183] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
OBJECTIVES The goal of this study was to investigate the nature of the association between silent ischemia and postoperative myocardial infarction (PMI). BACKGROUND Silent ischemia predicts cardiac morbidity and mortality in both ambulatory and postoperative patients. Whether silent stress-induced ischemia is merely a marker of extensive coronary artery disease or has a closer association with infarction has not been determined. METHODS In 185 consecutive patients undergoing vascular surgery, we correlated ischemia duration, as detected on a continuous 12-lead ST-trend monitoring during the period 48 h to 72 h after surgery, with cardiac troponin-I (cTn-I) measured in the first three postoperative days and with postoperative cardiac outcome. Postoperative myocardial infarction was defined as cTn-I >3.1 ng/ml accompanied by either typical symptoms or new ischemic electrocardiogram (ECG) findings. RESULTS During 11,132 patient-hours of monitoring, 38 patients (20.5%) had 66 transient ischemic events, all but one denoted by ST-segment depression. Twelve patients (6.5%) sustained PMI; one of those patients died. All infarctions were non-Q-wave and were detected by a rise in cTn-I during or immediately after prolonged, ST depression-type ischemia. The average duration ofischemia in patients with PMI was 226+/-164 min (range: 29 to 625), compared with 38+/-26 min (p = 0.0000) in 26 patients with ischemia but not infarction. Peak cTn-I strongly correlated with the longest, as well as cumulative, ischemia duration (r = 0.83 and r = 0.78, respectively). Ischemic ECG changes were completely reversible in all but one patient who had persistent new T wave inversion. All ischemic events culminating in PMI were preceded by an increase in heart rate (delta heart rate = 32+/-15 beats/min), and most (67%) of them began at the end of surgery and emergence from anesthesia. CONCLUSIONS Prolonged, ST depression-type ischemia progresses to MI and is strongly associated with the majority of cardiac complications after vascular surgery.
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Affiliation(s)
- G Landesberg
- Department of Anesthesiology and Critical Care Medicine, Hadassah University Hospital, Ein-Kerem, Jerusalem, Israel.
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Ohtsuka S, Suzuki S, Ishikawa K, Uchida W, Yatsu T, Yamaguchi I. Norepinephrine release is increased in the hibernating heart, studied in a chronic canine model of myocardial hibernation. J Cardiovasc Pharmacol 2001; 36 Suppl 2:S35-41. [PMID: 11206718 DOI: 10.1097/00005344-200000006-00009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
We examined the change in cardiac sympathetic function in the hibernating heart. To induce hibernating hearts in dogs, we placed a nylon tube via the carotid artery in the left circumflex artery (LCx) and obstructed the LCx flow. The plasma norepinephrine (NE) and epinephrine (E) concentrations in the coronary sinus and the aorta were measured before and 1 week after the tube placement to evaluate the catecholamine release from the heart. The wall motion was followed by echocardiography and. 1 week after the tube placement, regional myocardial blood flow (RBF) was measured using colored microspheres. Also. the restorability of myocardial dysfunction was examined in other dogs by extracting the LCx tube 1 week after the placement. Finally, the heart was removed for pathological observation and dogs showing myocardial infarction were excluded. One week after placing the tube, wall thickening was reduced in the LCx area, but was not in the left anterior descending (LAD) area. Compared with the LAD area, RBF in the LCx area was decreased in the endocardium (p < 0.05), but was not in the epicardium. In other dogs, the reduced wall thickening in the LCx area was restored to normal levels 1 or 2 weeks after the tube extraction. Thereby, our dogs with the tube placed were considered to be models of myocardial hibernation. The plasma NE and E concentrations were not significantly changed by placing the tube, but NE release from the heart was increased after the tube placement (p < 0.05). E uptake from the heart did not differ. Therefore, it is suggested that NE release is increased in the hibernating heart and may contribute to its mechanism.
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Affiliation(s)
- S Ohtsuka
- Department of Internal Medicine, Institute of Clinical Medicine, University of Tsukuba, Ibaraki-ken, Japan.
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Vanoverschelde JL, Melin JA. The pathophysiology of myocardial hibernation: current controversies and future directions. Prog Cardiovasc Dis 2001; 43:387-98. [PMID: 11251126 DOI: 10.1053/pcad.2001.20655] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
It is now widely accepted that patients with chronic coronary artery disease can experience prolonged regional ischemic dysfunction that does not necessarily arise from irreversible tissue damage and, to some extent, can be reversed by restoration of blood flow. Recent clinical and experimental data suggest that this form of chronic but reversible left ventricular dysfunction represents a complex, progressive, and dynamic phenomenon. The initial stages of dysfunction are probably caused by chronic stunning. They are characterized by normal resting perfusion but reduced flow reserve, mild myocyte alterations, maintained membrane integrity (allowing the transport of both thallium and glucose), preserved capacity to respond to an inotropic stimulus, and no or little tissue fibrosis. After revascularization, functional recovery will probably be rapid and complete. On the other hand, the more advanced stages of dysfunction likely correspond to chronic hibernation. They usually are associated with reduced rest perfusion; increased tissue fibrosis; more severe myocyte alterations (degeneration[?], apoptosis); and a decreased ability to respond to inotropic stimuli. Nonetheless, membrane function and glucose metabolism may long remain preserved. After revascularization, functional recovery, if any, will probably be quite delayed and mostly incomplete.
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Affiliation(s)
- J L Vanoverschelde
- Divisions of Cardiology, Université Catholique de Louvain, Brussels, Belgium
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Affiliation(s)
- R Schulz
- Department of Pathophysiology, Centre of Internal Medicine, University of Essen, School of Medicine, Hufelandstrasse 55, 45122 Essen, Germany
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Schwarz ER, Reffelmann T, Schoendube F, Hermanns B, Chakupurakal R, Doerge H, Schuetz T, Foresti M, Messmer BJ, Radke PW, Hanrath P. Hypoxic Hypoperfusion Fails to Induce Myocardial Hibernation in Anesthetized Swine. J Cardiovasc Pharmacol Ther 1999; 4:235-247. [PMID: 10684545 DOI: 10.1177/107424849900400405] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND: Congenital origin of the left coronary artery from the pulmonary artery (ALCAPA) results in chronically dysfunctional myocardium with the partial ability to recover after revascularization. We attempted to establish an ALCAPA syndrome in anesthetized pigs for 24 hours and to compare it with stunned and infarcted myocardium. METHODS AND RESULTS: In group 1 (n = 12), a bypass graft was interposed between the pulmonary artery and the left anterior descending coronary artery (LAD). Reduction of flow in the LAD with gradual increases in flow from the pulmonary artery resulted in an incremental reduction of segment shortening (8.9 +/- 5.3% at 24 hours vs 26.6 +/- 10% at baseline, P <.005). In group 3 (n = 5), 2 cycles of 10-minute LAD occlusion resulted in decreased segment shortening with slow recovery (at 24 hours 18.7 +/- 1.3% vs 24.2 +/- 4% at baseline, segment shortening with slow recovery (at 24 hours 18.7 +/- 1.3% vs 24.2 +/- 4% at baseline, P <.05). In group 3 (n = 6), 1-hour LAD occlusion reduced segment shortening at 24 hours to 4.7 +/- 5.2% (P <.005 vs baseline). Histological analysis of the LAD territory revealed severe degeneration, myolysis, and alteration of the chromatin structure in group 1 comparable to ischemic cell death in group 3, whereas control areas and the LAD area in group 2 showed only minor structural alterations. Infarct size/risk area, as measured by tetrazolium staining, was 49.8 +/- 11.2% in group 1, 9.3 +/- 8.1% in group 2 (P <.005), and 60.3 +/- 9% in group 3. CONCLUSION: Hypoxic myocardial hypoperfusion from the pulmonary artery results in myocardial necrosis in anesthetized pigs. These findings are in contrast to the concept of myocardial hibernation in the ALCAPA syndrome because in this model, hypoxic hypoperfusion failed to induce adaptation to preserve myocardial structure.
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Affiliation(s)
- ER Schwarz
- Medical Clinic I, Institute of Pathology, Germany
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Firoozan S, Wei K, Linka A, Skyba D, Goodman NC, Kaul S. A canine model of chronic ischemic cardiomyopathy: characterization of regional flow-function relations. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 276:H446-55. [PMID: 9950844 DOI: 10.1152/ajpheart.1999.276.2.h446] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The controversy regarding the mechanism(s) of left ventricular (LV) dysfunction in chronic coronary artery disease is, in part, related to the lack of an appropriate animal model for this condition. We have developed such a model by placing Ameroid constrictors on proximal portions of coronary arteries in dogs who were euthanized (mean of 6 wk) after the development of severe global LV dysfunction noted on two-dimensional echocardiography. The LV end-systolic size nearly doubled (P < 0.001) over the observation period, and the percent change in LV size from end diastole to end systole decreased by >50% (P < 0.001). Regional dysfunction was noted in 23 of 24 myocardial beds analyzed within regions showing no gross evidence of infarction. In 10 of these beds, severe dysfunction was noted without a decrease in radiolabeled microsphere-derived myocardial blood flow (MBF). In 13 myocardial beds, decrease in function was associated with a decrease in MBF (P < 0.001), with close coupling noted between percent wall thickening and MBF. In the beds that exhibited an ultimate decrease in MBF, the decrease in function preceded the decrease in MBF. In conclusion, we describe chronic LV dysfunction in a canine model of multivessel stenosis that closely mimics chronic ischemic LV dysfunction in humans. Whereas regional function is severely reduced in this model, MBF is varied in different segments and at different times during the observation period. These results provide new insights regarding flow-function relations in chronic ischemic LV dysfunction.
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Affiliation(s)
- S Firoozan
- Cardiovascular Division, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA
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Abstract
Decreased myocardial contraction occurs as a consequence of a reduction in blood flow. The concept of hibernation implies a downregulation of contractile function as an adaptation to a reduction in myocardial blood flow that serves to maintain myocardial integrity and viability during persistent ischemia. Unequivocal evidence for this concept exists in scenarios of myocardial ischemia that lasts for several hours, and sustained perfusion-contraction matching, recovery of energy and substrate metabolism, the potential for recruitment of inotropic reserve at the expense of metabolic recovery, and lack of necrosis are established criteria of short-term hibernation. The mechanisms of short-term hibernation, apart from reduced calcium responsiveness, are not clear at present. Experimental studies with chronic coronary stenosis lasting more than several hours have failed to continuously monitor flow and function. Nevertheless, a number of studies in chronic animal models and patients have demonstrated regional myocardial dysfunction at reduced resting blood flow that recovered upon reperfusion, consistent with chronic hibernation. Further studies are required to distinguish chronic hibernation from cumulative stunning. With a better understanding of the mechanisms underlying short-term hibernation, it is hoped that these adaptive responses can be recruited and reinforced to minimize the consequences of acute myocardial ischemia and delay impending infarction. Patients with chronic hibernation must be identified and undergo adequate reperfusion therapy.
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Affiliation(s)
- G Heusch
- Department of Pathophysiology, Centre of Internal Medicine, University of Essen, School of Medicine, Germany
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Rahimtoola SH. Hibernating myocardium is hypoperfused. Basic Res Cardiol 1998; 92 Suppl 2:9-11. [PMID: 9457360 DOI: 10.1007/bf00797196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- S H Rahimtoola
- Division of Cardiology, University of Southern California, Los Angeles 90033, USA
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Sherman AJ, Harris KR, Hedjbeli S, Yaroshenko Y, Schafer D, Shroff S, Sung J, Klocke FJ. Proportionate reversible decreases in systolic function and myocardial oxygen consumption after modest reductions in coronary flow: hibernation versus stunning. J Am Coll Cardiol 1997; 29:1623-31. [PMID: 9180128 DOI: 10.1016/s0735-1097(97)00085-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
OBJECTIVES This study sought to determine whether modest short-term reductions in coronary flow can produce subsequent proportionate reductions in myocardial function and O2 consumption compatible with myocardial hibernation. BACKGROUND Acute studies indicate that myocardial energy utilization can be downregulated during moderate flow reduction. Whether this apparently beneficial adjustment persists into the reperfusion period is unsettled because most postischemic contractile dysfunction has been presumed to represent stunned or irreversibly injured myocardium. METHODS Responses of regional myocardial function and O2 consumption were assessed in chronically instrumented dogs after approximately 50% reductions in flow for 2 h (n = 8) or repeated 2-min total coronary occlusions (n = 6). RESULTS When unrestricted perfusion was restored after sustained partial occlusions, regional function and O2 consumption stabilized at proportionate, systematically decreased levels ([mean +/- SEM] 80 +/- 3.1% and 81 +/- 5.1% of control values, both p < 0.05) and then returned to control values within 24 h. Similar proportionate reductions occurred after as few as five cycles of brief total occlusion (79 +/- 5.1% and 83 +/- 1.6% of control values, both again p < 0.05); these persisted with additional occlusions and then returned to baseline values within 3 h. The absence of irreversible injury was documented histologically in both series. Sham animals (n = 5) showed no changes in regional function or O2 consumption throughout similar experimental periods. CONCLUSIONS Moderate decreases in coronary flow or repeated brief coronary occlusions can be followed by proportionate reversible reductions in regional systolic function and O2 consumption compatible with the traditional definition of myocardial hibernation. These findings emphasize the complexity of myocardial responses to flow restriction and call attention to limitations in characterizing reversibly hypocontractile myocardium as simply hibernating or stunned.
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Affiliation(s)
- A J Sherman
- Feinberg Cardiovascular Research Institute and Department of Medicine, Northwestern University Medical School, Chicago, Illinois 60611-3008, USA
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