No abstract available.
Myocardial Stunning*

BACKGROUND: Myocardial contractile dysfunction is often noticed without myocardial infarction, it may be due to myocardial stunning or hibernation. There are several case reports of myocardial stunning in patients with variant angina, but effect of recurrent myocardial spasm on myocardial contratile function in human is not well established. METHODS: To evaluate the effect of recurrent spasm-induced myocardial ischemia on myocardial contractile function, we analyzed the ejection fraction(by area-length method) and regional wall motion(by centerline method) at before and after intracoronary nitroglycerin in variant angina group and control group. Variant angina group consisted of 15 patients(LAD ; 10 patients, RCA ; 5 patients) and normal control group consisted of 6 patients. RESULTS: Ejection fraction increment after nitroglycerin infusion was not significant in normal control group, but that in variant angina group was significant(p<0.05). Pre-NG shortening fraction of LAD territory on both RAO and LAO view in patients with spasm in LAD was significantly lower than that in patients without spasm in LAD(RAO ; p<0.05, LAO ; p<0.01). On LAO view pre-NG shortening fraction of LAD territory in 6 patients with spasm and without significant fixed lesion was lower than that in patients without spasm in LAD(p<0.05). Shortening fraction increment after nitroglycerin infusion in LAD territory on both RAO and LAO view was significant in patients with spasm in LAD(RAO ; 0.05, LAO ; p<0.01), but that in LCX or RCA territory and that in LAD territory of patients without spasm in LAD was not significant. Shortening fraction increment after nitroglycerin infusion in RCA territory on LAO view was significant in patients with spasm in RCA(p<0.05), but that in LAD or LCX territory and that RCA territory of patients without spasm in RCA and was not significant. CONCLUSION: These observations suggest that recurrent coronary artery spasm results in reversible dysfunction of the ventricular global and regional contractility, and myocardial stunning may be the cause of this phenmenon.
Coronary Vessels* ; Hibernation ; Humans ; Myocardial Infarction ; Myocardial Ischemia ; Myocardial Stunning ; Nitroglycerin ; Spasm*

BACKGROUND: Myocardial calcium overload during reperfusion may contribute to myocardial stunning. The protective effect of nicardipine against post-ischemic myocardial dysfunction was investigated. METHODS: Twenty-two halothane-anesthetized dogs were subjected to 15 minutes of left anterior descending coronary artery (LAD) occlusion and subsequent 3 hour reperfusion. One group of dogs (n=11) received nicardipine (1 microgram/kg/min) and another group (n=11) received saline (0.5 ml/kg/h) through intracoronary catheter for 1 hour beginning 15 minutes before LAD occlusion. Systolic shortening (%SS) and preload recruitable stroke work slope (Mw), as an index of regional myocardial contractility, and IMP-tau (time constant of myocardial relaxation based on intramyocardial pressure (IMP)) and post-systolic shortening (%PSS), as an index of regional diastolic function, were evaluated. LAD blood flow was measured by Doppler flowmeters as well. RESULTS: Regional systolic as well as diastolic functions during acute myocardial ischemia were similar between the two groups. However, Mw recovered to the baseline value with the onset of reperfusion in the nicardipine group but was significantly decreased throughout the reperfusion period in the controls. After 3 hours of reperfusion, the nicardipine group had recovered 67% of %SS, compared with 20% of the control group. IMP-tau was restored to the baseline value by 60 min of reperfusion in the control group but was significantly prolonged in the nicardipine group throughout the reperfusion period. CONCLUSIONS: Intracoronary nicardipine enhances the recovery of regional contractile function but prolongs myocardial relaxation in the canine model of myocardial stunning.
Animals ; Calcium ; Catheters ; Coronary Vessels ; Dogs* ; Flowmeters ; Myocardial Ischemia ; Myocardial Stunning* ; Nicardipine* ; Relaxation ; Reperfusion ; Stroke

BACKGROUND: It was reported that N,N,N'N'-tetrakis-[2-pyridylmethyl]-ethylenediamine (TPEN), a transition metal chelator, confers cardioprotection against myocardial ischemic injury. In this study, we investigated the effect of TPEN targeting reperfusion period in isolated rat hearts. METHODS: Langendorff perfused rat hearts were subjected to 30 min of regional ischemia and 2 h of reperfusion. Hearts were randomly assigned to either control (n = 9) or 10 micrometer of TPEN (n = 8) groups. TPEN was perfused for a period of 5 min before and 30 min after reperfusion. RESULTS: The ratio of infarct area/ischemic area (AN/AR) was significantly reduced in TPEN treated hearts (6.9 +/- 1.7%, P < 0.001) compared to control hearts (29.5 +/- 3.2%). Recovery of left ventricular developed pressure (LVDP), rate-pressure product (RPP), +dP/dt(max), and -dP/dt(min) in the control group after reperfusion were 53.8 +/- 6.2%, 51.0 +/- 6.3%, 51.9 +/- 5.7%, and 51.4 +/- 5.7%, respectively, of the baseline levels. In the TPEN group, LVDP, RPP, +dP/dt(max), and -dP/dt(min) returned to 58.5 +/- 4.6%, 54.8 +/- 6.4%, 61.7 +/- 4.9%, and 53.4 +/- 3.9%, respectively, of the baseline levels. There were no significant differences in the cardiodynamic variables between the two groups (P > 0.05). CONCLUSIONS: Pharmacological postconditioning with TPEN reduces myocardial infarction however, TPEN does not modify post-ischemic systolic dysfunction in isolated rat hearts.
Animals ; Ethylenediamines ; Heart ; Ischemia ; Myocardial Infarction ; Myocardial Stunning ; Rats ; Reperfusion ; Reperfusion Injury

BACKGROUND: Incidence of diastolic dyssynchrony (DD) and its impact on functional recovery of left ventricle (LV) after ST segment elevation myocardial infarction (STEMI) is not known. METHODS: Consecutive patients with STEMI who underwent successful revascularization were prospectively enrolled. Echocardiography with tissue Doppler imaging was performed within 48 hours of admission and at 6 months. LV end-diastolic volume index (EDVI), end-systolic volume index (ESVI), ejection fraction (EF), and left atrial volume index (LAVI) were calculated. Diastolic delay was calculated from onset of QRS complex to peak of E wave in tissue Doppler image and presented as maximal temporal difference between peak early diastolic velocity of 6 basal segments of LV (TeDiff). Study patients were compared with demographically matched control group. RESULTS: Forty eight consecutive patients (55 ± 10 years, 88% male) and 24 controls (56 ± 6 years, 88% male) were included. TeDiff was higher in STEMI than in controls (35.9 ± 19.9 ms vs. 26.3 ± 6.8 ms, p = 0.025). Presence of DD was higher in STEMI than controls (58% vs. 33%, p = 0.046) according to calculated cut-off value (≥ 29 ms). There was no correlation between TeDiff and change in EDVI, ESVI, and LAVI at 6 months, however TeDiff and change in EF at 6 months was positively correlated (r = 0.328, p = 0.023). Patients with baseline DD experienced remodeling less frequently compared to patients without baseline DD (11% vs. 38%, p = 0.040) during follow-up. CONCLUSION: STEMI disrupts diastolic synchronicity of LV. However, DD during acute phase of STEMI is associated with better recovery of LV thereafter. This suggests that DD is associated with peri-infarct stunned myocardium that is salvaged with primary intervention as well as infarct size.
Echocardiography ; Follow-Up Studies ; Heart Ventricles* ; Humans ; Incidence ; Myocardial Infarction* ; Myocardial Stunning ; Prospective Studies

The potential for recovery of left ventricular dysfunction after myocardial revascularization represents a practical clinical definition for myocardial viability. The evaluation of viable myocardium in patients with severe global left ventricular dysfunction due to coronary artery disease and with regional dysfunction after acute myocardial infarction is an important issue whether left ventricular dysfunction may be reversible or irreversible after therapy. If the dysfunction is due to stunning or hibernation, functional improvement is observed. but stunned myocardium may recover of dysfunction with no revascularization. Hibernation is chronic process due to chronic reduction in the resting myocardial blood flow. There are two types of myocardial hibernation: "functional hibernation" with preserved contractile reserve and "structural hibernation" without contractile reserve in segments with preserved glucose metabolism. This review focus on the application of F-18 FDG and other radionuclides to evaluate myocardial viability. In addition the factors influencing predictive value of FDG imaging for evaluating viability and the different criteria for viability are also reviewed.
Coronary Artery Disease ; Glucose ; Hibernation ; Humans ; Metabolism ; Myocardial Infarction ; Myocardial Revascularization ; Myocardial Stunning ; Myocardium ; Radioisotopes ; Ventricular Dysfunction, Left

BACKGROUND AND OBJECTIVES: Doppler myocardial imaging (DMI) has been suggested as a method of quantifying inducible ischemia during dobutamine stress echocardiography (DSE). Post-systolic motion (PSM) detected by DMI is related to peri-infarct ischemia during DSE. We hypothesized that PSM during DSE would predict recovery of dysfunctional myocardium after successful percutaneous coronary intervention (PCI). SUBJECTS AND METHODS: Thirty patients with dysfunctional myocardium in the left anterior descending coronary artery (LAD) territory were divided into two groups according to improvement of wall motion score index (WMSI) in the LAD territory at 6 months after successful PCI of the LAD. DMI was evaluated in the LAD territory during DSE. Fifteen patients showed improved WMSI (1.42+/-0.39) while the other 15 had unchanged WMSI (1.75+/-0.46) 1 month after PCI. Myocardial velocity was measured in the mid-septal, apico-septal, and basal anterior segments of the LAD artery territory. PSM was defined as a positive wave appearing after the curve of systolic ejection had reached the zero line. RESULTS: Although there was no difference between resting PSMs in both groups, PSM during DSE was significantly higher in the improved WMSI group than in the WMSI group where it was unchanged. CONCLUSION: PSM during DSE predicts recovery of dysfunctional myocardium after successful PCI.
Arteries ; Coronary Vessels ; Dobutamine ; Echocardiography, Stress ; Humans ; Ischemia ; Myocardial Stunning ; Myocardium ; Percutaneous Coronary Intervention

We performed 1st day Tc-99m-sestamibi gated SPECT with dipyridamole/rest T1-201 SPECT and 2nd day 24 hour delay T1-201 SPECT/rest Tc-99m-sestamibi gated SPECT in 27 patients with coronary artery disease(24) or having chest pain(3). Stress and rest Tc-99m- sestamibi gated SPECT was acquired at 60min post-injection. A 4-point scoring system(0 to 3 for normal to absent tracer uptake) for 17 segments was used. Wall motion was scored on another 4 point scale(0 to 3 for normal to dyskinesia) in the lst day post-stress gated and the 2nd day rest gated SPECT. Post-stress gated SPECT showed wall motion abnormality in 94 segments(20%). Fifty-five segments among these 94 showed the same wall motion between post-stress and rest gated SPECT:i.e. 1-1: 23 segments, 2-2: 29 segments, 3-3: 3 segments. Re-maining 39 segments (41.5%) showed different wall motion between post-stress and rest Tc-99m-sestamibi gated SFECT. Twenty one segments with wall motion abnormality had normal perfusion(rest:15 segments, 24 hour delay: 6 segments) at either rest or 24 hour delay. Fifteen among these 21 segments showed persistent post-stress and the 2nd day rest wall motion abnormality(persistent stunning). However, in 6 segments with prolonged (1 hour after stress) stunning, abnormal wall motion did improve in the 2nd day rest Tc-99m-sestamibi gated SPECT(transient prolonged stunning). These 6 segments had normal perfusion at rest(n=4) or at 24 hour delay(n=2). Post stress wall motions showed significantly higher scores in persistent stunning than in prolonged transient stunning(P value<0.05). It was concluded that we could find stunned myocardium with gated Tc-99m-sestamibi SPECT at either post-stress or rest and that some myocardial walls of post-stress 1 hour gated SPECT did not show truly rest wall motion. So, we should be cautious if we use post-stress Tc-99m-sestamibi wall motion to assess rest wall motion.
Coronary Vessels ; Dipyridamole* ; Humans ; Myocardial Stunning ; Perfusion ; Thorax ; Tomography, Emission-Computed, Single-Photon*

BACKGROUND: Brief episodic ischemias prior to subsequent prolonged ischemia limit infarct size and attenuate the reperfusion arrythmia. But the effect of ischemic preconditioning on post-ischemic myocardial dysfunction, coronary flow and nitric oxide (NO) remains unclear. METHODS: To investigate the effect of ischemic preconditioning on myocardial function and coronary flow during reperfusion after 15 minutes of global myocardial ischemia, 30 isolated hearts of Sprague-Dowley rats were perfused under constant pressure. Two episodes of three minutes global ischemia followed by 12 minutes of reflow were employed to precondition the hearts. The hearts were randomized to one of three groups : group I had no preconditioning, group II had preconditioning, group III had preconditioning as well as L-arginine pretreatment. Left ventricular developed pressure (LVDP), LV dp/dt, perfused coronary flow, concentration of NO and heart rate were continuously measured. RESULTS: In preconditioning groups (Group II, Group III), LVDP decreased during reflow and was lower than that of the control group. LV dp/dt decreased after reflow and gradually recovered with time but recovered was less in preconditioning groups. Coronary flow increased in the first few minutes after reflow in all groups, but decreased gradually. The decrease of coronary flow was greater in preconditioning groups. NO increased during the first 10 minutes after reflow and then decreased. In preconditioning groups, NO tends to be lower than that in the non-preconditioning group. CONCLUSION: Ischemic preconditioning was not beneficial to post-ischemic myocardial dysfunction, coronary flow and NO concentration in the flow. Cummulative effect of stunning due to repetitive ischemia for preconditioning may be an explanation for worse post-ischemic myocardial dysfunction and coronary flow in preconditioning groups.
Animals ; Arginine ; Arrhythmias, Cardiac ; Heart Rate ; Heart* ; Ischemia ; Ischemic Preconditioning* ; Myocardial Ischemia ; Myocardial Stunning ; Nitric Oxide ; Rats* ; Reperfusion

BACKGROUND AND OBJECTIVES: An abnormal Q wave, after an acute myocardial infarction, has been considered an indicator of myocardial necrosis. However, in some cases this Q wave partially or completely disappears during the evolution of the myocardial infarction. The clinical significance of Q wave regression remains to be established. Accordingly, this study was conducted to evaluate the relationship between Q wave regression, after an anterior wall acute myocardial infarction, and the improvements of the regional wall motion abnormality and left ventricular ejection fraction in echocardiography. SUBJCETS AND METHODS: A total of 80 patients, who presented with a first anterior wall acute myocardial infarction, managed successfully with direct intervention, were divided into two groups according to the regression (group A) or presence (group B) of abnormal Q waves. Regression of an abnormal Q wave was defined as the disappearance of the Q wave and reappearance of the R wave > or =0.1 mV, in at least two of the I, aVL, and V1 to V6 leads. RESULTS: Of the 80 patients, 26 (32.5 %) had an abnormal Q wave regression within 12 months. The peak creatine kinase-MB activity was lower in group A than B (277.3+/-202.6 vs. 521.3+/-284.4 ng/dL, pc<0.01). Group A had better left ventricular regional wall motion than group B in the initial echocardiograms. The degree of improvement of the left ventricular ejection fraction and regional wall motion between the initial and follow-up echocardiographies were significantly greater in group A than B. CONCLUSION: Patients with an anterior wall acute myocardial infarction, showing Q wave regression, tended towards a smaller amount of necrotic myocardium and a significantly larger amount of stunned myocardium.
Creatine ; Echocardiography ; Follow-Up Studies ; Humans ; Myocardial Infarction* ; Myocardial Stunning ; Myocardium ; Necrosis ; Stroke Volume ; Ventricular Function, Left