Dependency of Contractile Reserve on Myocardial Blood Flow

Lee, Hans H.; Dávila‐Román, Víctor G.; Ludbrook, Philip A.; Courtois, Michael; Walsh, John F.; Delano, Deborah A.; Rubin, Patricia J.; Gropler, Robert J.

doi:10.1161/01.cir.96.9.2884

Cited by 61 publications

(9 citation statements)

References 40 publications

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“…19,20 Thus, the test simulates effects of revascularization. The myofiber shortening and wall thickening induced by dobutamine predominantly affect the inner layers of segments with subendocardial infarcts, 21 but midwall and subepicardial inotropic reserve had a prognostic impact on RECOVERY.…”

Section: Dsmrmentioning

confidence: 99%

Magnetic Resonance Low-Dose Dobutamine Test Is Superior to Scar Quantification for the Prediction of Functional Recovery

Wellnhofer¹,

Olariu²,

Klein³

et al. 2004

Circulation

288

145

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Background-Low-dose dobutamine challenge (DSMR) by MRI was compared with delayed enhancement imaging with Gd-DTPA (SCAR) as a predictor of improvement of wall motion after revascularization (RECOVERY). Methods and Results-In 29 patients with coronary artery disease (68Ϯ7 years of age, 2 women, 32Ϯ8% ejection fraction), wall motion was evaluated semiquantitatively by MRI before and 3 months after revascularization. SCAR and DSMR were performed before revascularization. The transmural extent of scar was assessed semiquantitatively.

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Section: Dsmrmentioning

confidence: 99%

Magnetic Resonance Low-Dose Dobutamine Test Is Superior to Scar Quantification for the Prediction of Functional Recovery

Wellnhofer¹,

Olariu²,

Klein³

et al. 2004

Circulation

288

145

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“…Despite the recognized complexity of the issue, however, it is generally agreed that dysfunctional regions displaying contractile reserve can increase perfusion during stimulation, whereas those without contractile reserve cannot (61,99). Thus it is usually accepted that most regions showing inotropic reserve (before reperfusion) could benefit from reperfusion in terms of mechanical performance because of regionally enhanced perfusion.…”

Section: Working Hypothesismentioning

confidence: 99%

Mechanisms leading to reversible mechanical dysfunction in severe CAD: alternatives to myocardial stunning

Mazzadi

André‐Fouët²,

Costes³

et al. 2006

American Journal of Physiology-Heart and Circulatory Physiology

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Croisille, Didier Revel, and Marc F. Janier. Mechanisms leading to reversible mechanical dysfunction in severe CAD: alternatives to myocardial stunning. Am J Physiol Heart Circ Physiol 291: H2570 -H2582, 2006. First published July 21, 2006 doi:10.1152/ajpheart.01249.2005.-Patients with severe chronic coronary artery disease (CAD) exhibit a highly altered myocardial pattern of perfusion, metabolism, and mechanical performance. In this context, the diagnosis of stunning remains elusive not only because of methodological and logistic considerations, but also because of the pathophysiological characteristics of the myocardium of these patients. In addition, a number of alternative pathophysiological mechanisms may act by mimicking the functional manifestations usually attributed to stunning. The present review describes three mechanisms that could theoretically lead to reversible mechanical dysfunction in these patients: myocardial wall stress, the tethering effect, and myocardial expression and release of auto-and paracrine agents. Attention is focused on the role of these mechanisms in scintigraphically "normal" regions (i.e., regions usually showing normal perfusion, glucose metabolism, and cellular integrity as assessed by nuclear imaging techniques), in which stunning is usually considered, but these mechanisms could also operate throughout the viable myocardium. We hypothesize that reversion of these three mechanisms could partially explain the unexpected functional benefit after reperfusion recently highlighted by high-spatial-resolution imaging techniques. stunned myocardium; hibernating myocardium; inotropic reserve; cardiac imaging; myocardial wall stress; ventricular remodeling SUMMARY OF CLINICAL PROBLEMIN RECENT YEARS, WIDESPREAD utilization of noninvasive cardiac imaging methods has greatly improved the synergy between clinical and basic investigation of cardiac ischemic pathophysiology. Thus imaging methods have shown that the reversible left ventricular (LV) dysfunction arising from brief coronary occlusion and reflow (myocardial stunning), first described in animal models (80), occurs in humans. Two major hypotheses explain this phenomenon: 1) the oxyradical hypothesis, which proposes that oxidant stress impairs LV function (18), and 2) the calcium hypothesis, which postulates that stunning results from disturbed myocyte calcium homeostasis (98). On the other hand, the hibernating myocardium (136, 137) was first discovered by imaging methods in humans, and it was originally defined as "resting LV dysfunction due to reduced coronary blood flow that can be partially or completely reversed by myocardial revascularization and/or by reducing myocardial oxygen demand" (136). The concept was refined when ultrastructural investigations showed a distinctive morphology for hibernating myocardium, generally without necrosis, but with loss of sarcomeres and myofibrils (suggesting a "dedifferentiation" process toward an embryonic phenotype), with loss of mitochondria and increased glycogen storage (9,19,27,162)...

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“…Furthermore, the response to positive inotropic stimulation requires a substantial amount of functional myocytes in a given segment [24] , although viability may be detected in small areas when function is precluded by histopathological remodelling. A positive response to an inotropic stimulation also requires some coronary flow reserve [25][26][27] . Our data show that assessment of diastolic wall thickness by echocardiography as a single observation provides important clinical information.…”

Section: Baseline Echocardiography and Dobutamine Echocardiographymentioning

confidence: 99%

Sensitivity, specificity, and predictive accuracies of non-invasive tests, singly and in combination, for diagnosis of hibernating myocardium

LaCanna

Rahimtoola

Visioli

et al. 2000

European Heart Journal

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Objective To determine the best test(s) for predicting functional recovery of hibernating myocardium after reperfusion.Methods A prospective study to compare echocardiographic left ventricular diastolic wall thickness (d5 mm), low-dose dobutamine echocardiography and restredistribution thallium-201 scintigraphy, alone and in combination, for predicting recovery of left ventricular akinesis after surgical revascularization.Results Twenty-eight consecutive patients aged 58 9 years were studied. Of the 448 left ventricular segments, 263 were akinetic at rest; 230/263 (87%) had wall thickness d5 mm, 135 (51%) had a positive response and 175 (66·5%) were graded viable on thallium. Of akinetic segments 61% improved after surgery. Left ventricular score decreased from 2·3 0·4 to 1·8 0·4 (P<0·01) and ejection fraction increased from 27 10 to 37 14% (P<0·01). For predicting results at 1 year, diastolic wall thickness had a sensitivity and a predictive accuracy of a negative test of 100% but a specificity of 28% and predictive accuracy of a positive test of 61%. The addition of dobutamine echocardiography or thallium-201 improved the predictive accuracy of a positive test to 76% and 69%, respectively; the addition of both tests was not of greater benefit than that of a single test.Conclusions Diastolic wall thickness <5 mm on echocardiography was the best simple and single predictor of non-recovery of left ventricular dysfunction. The addition of dobutamine echocardiography or thallium-201, but not both, was the best solution for predicting recovery of left ventricular dysfunction. In times of limited resources, these findings are important from a clinical point of view.

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Dependency of Contractile Reserve on Myocardial Blood Flow

Abstract: Contractile reserve depends, in part, on the level of myocardial blood flow at rest and during inotropic stimulation.

Cited by 61 publications

References 40 publications

Magnetic Resonance Low-Dose Dobutamine Test Is Superior to Scar Quantification for the Prediction of Functional Recovery

Magnetic Resonance Low-Dose Dobutamine Test Is Superior to Scar Quantification for the Prediction of Functional Recovery

Mechanisms leading to reversible mechanical dysfunction in severe CAD: alternatives to myocardial stunning

Sensitivity, specificity, and predictive accuracies of non-invasive tests, singly and in combination, for diagnosis of hibernating myocardium

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