Metabolic and functional recovery of ischemic human myocardium after coronary angioplasty

Abstract

Although revascularization of hypoperfused but metabolically active human myocardium improves segmental function, the temporal relations among restoration of blood flow, normalization of tissue metabolism and recovery of segmental function have not been determined. To examine the effects of coronary angioplasty on 13 asynergic vascular territories in 12 patients, positron emission tomography and two-dimensional echocardiography were performed before and within 72 h of revascularization. Ten patients underwent late echocardiography (67 +/- 19 days) and eight underwent a late positron emission tomographic study (68 +/- 19 days). The extent and severity of abnormalities of wall motion, perfusion and glucose metabolism were expressed as wall motion scores, perfusion defect scores and perfusion-metabolism mismatch scores. Angioplasty significantly increased mean stenosis cross-sectional area (from 0.95 +/- 0.9 to 2.7 +/- 1.4 mm2) and mean cross-sectional luminal diameter (from 0.9 +/- 0.6 to 1.9 +/- 0.5 mm) (both p less than 0.001). Perfusion defect scores in dependent vascular territories improved early after angioplasty (from 116 +/- 166 to 31 +/- 51, p less than 0.002) with no further improvement on the late follow-up study. The mean perfusion-metabolism mismatch score decreased from 159 +/- 175 to 65 +/- 117 early after angioplasty (p less than 0.01) and to 26 +/- 29 at late follow-up (p less than 0.001 vs. before angioplasty; p = NS vs. early after angioplasty). However, absolute rates of glucose utilization remained elevated early after revascularization, normalizing only at late follow-up.(ABSTRACT TRUNCATED AT 250 WORDS)

Medical and Cellular Implications of Stunning, Hibernation, and Preconditioning

“…Nienaber et al 117 observed improvements in left ventricular function after PTCA. They studied the effect of PTCA using PET scanning and two-dimensional echocardiography before PTCA, within 72 hours of revascularization, and late (67 to 68 days) after PTCA.…”

“…105,106 More recently, the variable chronicity of hibernation has been highlighted, 117,122 leading to the hypothesis that the longer the ischemia, the slower the subsequent recovery. 155 Virtually all the animal models of hibernation have investigated the myocardial response to acute, low-grade ischemia, 105,156,157 a situation that may or may not have common clinical correlates.…”

Characterization of Dysfunctional Myocardium by Positron Emission Tomography and Magnetic Resonance

“…In this class of segments, a high portion of mismatch segments was found that are generally associated with a high likelihood of functional recovery. 2,6,7 However, only one third of these segments improved in postoperative function. This finding of metabolically viable myocardium that does not recover function after revascularization might be explained by a loss of contractile material in these segments to an extent that precludes contractile recovery.…”

“…[2][3][4][5][6][7] Up to 83% to 95% [7][8][9] of segments with inotropic reserve on ␤ 1 -adrenergic stimulation recover function after revascularization. Although scintigraphic techniques appear more sensitive for detection of viability, their specificity to predict functional recovery is in general somewhat lower, ranging from 48% to 82%.…”

Downregulation of Immunodetectable Connexin43 and Decreased Gap Junction Size in the Pathogenesis of Chronic Hibernation in the Human Left Ventricle

“…Histological and electron microscopic examination of biopsy material obtained from hibernating regions reveal a variable degree of fibrous tissue replacement, with a proportion of the myocytes showing depleted contractile material, numerous and small mitochondria, and irregular nuclear envelopes. 3,4 Although early studies suggested that such altered myocytes characterized the hibernating state 3 and could explain the delay in recovery in contractile function after successful revascularization, 5 more recent reports have described them in equal frequency in both hibernating and nonhibernating ventricular segments. 4,6 Similar cellular features have also been described in ventricular specimens from patients with dilated, nonischemic cardiomyopathy 7 as well as in rat cardiac myocytes after a short period of unloading.…”