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PubMed1993

Elevated plasma lipoprotein(a) associated with abnormal stress thallium scans in children with familial hypercholesterolemia.

Plasma lipoprotein(a) (Lp(a)) concentrations are associated with an increased risk of coronary artery disease in adults with familial hypercholesterolemia (FH). We hypothesized that Lp(a) concentrations in children with FH were higher among those with myocardial ischemia on stress thallium scans and among those with a family history of premature coronary artery disease. Twenty-nine asymptomatic heterozygotes with FH (range 9 to 23 years) and 7 homozygotes (range 4 to 13 years) were evaluated with clinical assessment, lipoprotein measurement and stress thallium scans. Compared with subjects with normal stress thallium scans, mean Lp(a) was significantly higher in homozygotes with stress thallium abnormalities (79 +/- 18 vs 15 +/- 5.5 mg/dl, p = 0.03), and tended to be higher in heterozygotes with stress thallium abnormalities (39 +/- 12 vs 20 +/- 4.2 mg/dl, p = 0.10). Lp(a) tended to be higher in heterozygotes with a family history of premature coronary artery disease (30 +/- 6.4 vs 14 +/- 4.1 mg/dl, p = 0.12). It is concluded that Lp(a) is higher in hypercholesterolemic children who have abnormal stress thallium scans. Lp(a) may be useful in assessing coronary artery disease risk in children with FH.

Adolescent↗
PubMed1994

Prognostic significance of a fixed thallium defect one to six months after onset of acute myocardial infarction or unstable angina. Multicenter Myocardial Ischemia Research Group.

In a large prospective study of myocardial ischemia, exercise thallium studies were performed in 896 patients 1 to 6 months after an acute coronary event (acute myocardial infarction, 70%; unstable angina, 30%). Thallium images were analyzed quantitatively and classified as normal or demonstrating either a reversible defect after 2 to 4 hours or having only a fixed defect. The effect of the thallium findings on the time to end point (cardiac death, nonfatal infarction, or unstable angina) were examined by Kaplan-Meier curves and compared using the log-rank statistic. Follow-up averaged 23 months. The likelihood of cardiac death, nonfatal infarction, and unstable angina was similar in patients who had a normal exercise thallium test result or showed only a fixed defect. Moreover, cardiac events were not related to the size of a fixed defect. In contrast, both cardiac death and nonfatal infarction were increased in patients with the largest areas of reversible defects, although the sensitivity for nonfatal myocardial infarction was suboptimal. The presence of a fixed defect on exercise thallium in patients who are stable an average of 2.6 months after an acute cardiac event is associated with a prognosis similar to that of a normal exercise thallium test.

Angina, Unstable↗
PubMed1994

Influence of exercise-induced coronary artery spasm on thallium-201 initial distribution and washout kinetics in patients with variant and classic angina pectoris.

Thallium-201 single-photon emission computed tomography was performed immediately, and 2 and 4 hours after exercise-induced anginal attack in 2 groups of patients with either exercise-induced coronary spasm or severe fixed stenosis on the isolated proximal left anterior descending coronary artery. All patients with variant angina had transient ST-segment elevation during the exercise-induced attack for thallium-201 scintigraphic study. Both perfusion defects and 4-hour washout abnormalities were significantly greater in patients with variant angina than in those with stable effort angina (p < 0.01). In patients with stable effort angina, thallium-201 activity in ischemic regions (as a percentage of initial count in the normal region) progressively decreased, whereas in patients with variant angina it increased from 38% (initial) to 48% (2 hours), and then declined to 42% (4 hours). The initial normalized thallium-201 activity in the ischemic regions was significantly lower in patients with variant angina than in those with stable effort angina (p < 0.001). In conclusion, perfusion and washout abnormalities during exercise-induced angina are greater in patients with variant angina than in those with stable effort angina. Exercise-induced coronary spasm seems to contribute to the profound reduction in initial thallium-201 distribution and delayed thallium-201 accumulation in the ischemic region.

Adult↗
PubMed1983

Predictive value of thallium stress testing for coronary and cardiovascular events in uremic diabetic patients before renal transplantation.

Coronary artery disease and the ability of noninvasive exercise perfusion imaging with thallium-201 to predict future coronary and cardiovascular events was prospectively evaluated in a group of 85 insulin-dependent diabetic renal transplantation candidates. Sixty patients received renal allografts (36 living related donors, 24 cadaver donors) after a thallium stress test; the actuarial 2 year patient survival rate after transplantation was 84 percent. Twenty-five patients remained on dialysis, and the 2 year actuarial survival rate from onset of dialysis was 41 percent, significantly lower than the actuarial survival rate of transplanted patients (p less than 0.01). Thirteen transplanted patients had positive thallium stress test results, and 6 (46 percent) had cardiovascular events (two fatal). In contrast, of 47 transplant patients with negative thallium stress test results, only 13 (28 percent) had cardiovascular events (four fatal). Five patients treated by hemodialysis only had positive test results and three (60 percent) had cardiovascular events (two fatal), whereas of 20 hemodialysis patients with negative test results, 9 (45 percent) suffered cardiovascular events (four fatal). In this study, cardiovascular events included arrhythmia, stroke, and pulmonary embolism. Within the total group, 4 of 18 patients (22 percent) with a positive test result (22 percent) had a fatal myocardial infarction, whereas only 3 of 67 patients (4 percent) with a negative result had a fatal myocardial infarction (p less than 0.05). In comparison, 24 of 85 patients had a history or electrocardiographic evidence of preexisting cardiovascular disease, and 13 (54 percent) had subsequent cardiovascular events (5 of 11 patients with positive test results and 8 of 13 patients with negative results). In summary, renal transplant candidates with positive thallium stress test results appear to be at increased risk compared with those with negative results for the development of fatal myocardial infarction, but thallium stress testing is no more predictive for future coronary and cardiovascular events than is a history or an abnormal electrocardiogram.

Adult↗
PubMed1986

Alteration of hepatocellular structure and function by thallium chloride: ultrastructural, morphometric, and biochemical studies.

The effects of thallium chloride (TlCl3.4H2O) on hepatocyte structure and function were studied in male rats at 16 hr following treatment by ip injection with doses of 0, 50, 100, and 200 mg/kg. Ultrastructural examination of hepatocytes from thallium-treated rats showed a dose-related loss of ribosomes from the endoplasmic reticulum and proliferation of the rough endoplasmic reticulum segment. Generalized mitochondrial swelling and increased numbers of electron-dense autophagic lysosomes were also observed. Morphometric analysis of hepatocytes from thallium-treated rats disclosed a 3-fold increase in the volume density of the lysosomal compartment and a 1.3-fold increase in the volume density of mitochondrial. Surface density measurements of mitochondrial and endoplasmic reticulum membranes showed dose-related increases in the surface density of both inner and outer mitochondrial membranes as well as of the rough endoplasmic reticulum. These structural changes were associated with pronounced increases in the specific activities of the mitochondrial membrane-associated enzymes monoamine oxidase and ferrochelatase to 145 and 144% of control values, respectively, and a 42% decrease in the activity of aminolevulinic acid (ALA) synthetase. Similarly, structural alteration of the endoplasmic reticulum in thallium-treated rats was associated with concomitant impairment of the microsomal enzymes NADPH cytochrome c (P-450) reductase, aniline hydroxylase, and aminopyrene demethylase to a maximum of 49, 43, and 77% of activities seen in untreated controls, respectively. In contrast, the non-membrane-bound enzymes malate dehydrogenase, ALA dehydratase, and uroporphyrinogen I synthetase were unaltered in vivo following thallium treatment at any doses. These results indicate that thallium-induced alteration of hepatic biochemical processes may arise from physical disruption of the membranal integrity of subcellular organelles with which those processes are functionally associated. These findings are consistent with those from previous studies in demonstrating a positive quantitative correlation between metal-induced subcellular organelle membrane structural injury and impairment of associated biological functions in vivo.

5-Aminolevulinate Synthetase↗
PubMed1988

Environmental exposure to thallium.

This paper reviews recent data and findings concerning the sources of thallium in the environment and its current environmental levels and exposures, particularly with respect to human exposure. Special emphasis is given to some recent cases of environmental thallium pollution that were recognized around several cement factories in the Federal Republic of Germany. Contaminated food grown in these areas gave rise to a significantly increased thallium exposure of the population living there. Recent studies show that the thallium level in human urine normally is below 1 micrograms/g creatinine and that the normal concentration range of thallium in human air is approximately 5-10 ng/g. These data allow to recognize even minor undue exposure to thallium in the work and general environment.

Environmental Exposure↗
PubMed1989

Evaluation of myocardial thallium tomography in patients with chest pain.

Thirty-seven patients with chest pain have been studied by exercise thallium tomography and coronary arteriography to assess the accuracy of thallium tomography in the identification of patients with coronary artery disease and to evaluate whether knowledge of clinical data improves this accuracy. Thallium tomography was also used to identify which coronary arteries were stenosed. Thallium tomography when compared with coronary arteriography has a sensitivity of 97%, a specificity of 75%, and an overall accuracy of 92% for the detection of coronary artery disease. When clinical information was made available, these results improved to a sensitivity of 100%, a specificity of 75%, and an overall accuracy of 95%. In the identification of which coronary arteries were stenosed, thallium tomography had a sensitivity of 85%, a specificity of 89%, and an overall accuracy of 86%. These results show that exercise thallium tomography can be an accurate non-invasive screening test in patients with chest pain thought to be angina.

Angina Pectoris↗
PubMed1990

Exercise myocardial perfusion scintigraphy with technetium-99m methoxy isobutylisonitrile: a comparative study with thallium-201.

The evaluation of technetium-99m methoxy isobutylisonitrile for the diagnosis of coronary artery disease requires comparative validation against thallium-201, the established perfusion imaging agent. We have compared myocardial and lung uptake of both radiotracers following maximal exercise in 52 patients: 40 with angiographically proven coronary disease. Qualitative and quantitative image analysis showed the diagnostic sensitivity of technetium-99m methoxy isobutylisonitrile to compare favourably with that of thallium-201 as reflected by the mean number of ischaemic segments identified: 5.6 +/- 2.5 vs 4.8 +/- 2.1 by qualitative analysis, and 5.7 +/- 3.2 vs 5.0 +/- 2.6 segments by quantitative analysis. More reversibly ischaemic segments per patient were identified with technetium-99m methoxy isobutylisonitrile than with thallium-201: 3.6 +/- 2.3 vs 1.8 +/- 1.9. There was a higher exercise myocardial to background count ratio with technetium-99m methoxy isobutylisonitrile: 3.16:1 vs 2.58:1, and the mean exercise lung uptake normalised to left ventricular uptake ('lung index'), was lower for technetium-99m methoxy isobutylisonitrile than for thallium-201 (36 +/- 8% vs 40 +/- 10%). Five of the six patients with abnormal elevation of the thallium-201 exercise lung index also had elevation of the technetium-99m methoxy isobutylisonitrile exercise lung index, and all had extensive coronary artery disease. These results indicate that technetium-99m methoxy isobutylisonitrile is at least as effective as thallium-201 for detecting exercise induced myocardial ischaemia. However, technetium-99m methoxy isobutylisonitrile provides a better image quality and may be a more sensitive marker of defect reversibility. For both radiotracers lung uptake is increased with extensive coronary artery disease and measurement of this variable provides prognostic information.

Coronary Disease↗
PubMed1994

Thallium distribution in organs and brain regions of developing rats.

The concentration of thallium in body organs and brain regions was studied in rats as a function of the animals age from newborn to 20-days old. Thallium was analyzed at different times after a single sublethal i.p. injection of the metal (16 mg/kg). The results indicate that the brain is less permeable to thallium in the older animals, suggesting that reduced thallium transport into the brain is related to the establishment of the blood-brain barrier in the rats. Differences between weanling and newborn rats were also found in regard to regional distribution of thallium in the brain as the older animals showed a region-dependent distribution while newborn rats presented an homogeneous content of thallium among all regions.

Aging↗
PubMed1982

Placental transfer and retention of 201Ti-thallium in the rat.

Placental transfer of thallium was evidenced in rats treated with a single intraperitoneal dose of 2 micrograms 201T1-labelled thallium/rat on the 13th day of pregnancy. Both maternal and fetal organs showed remarkable thallium retention, approx. 10% of the dose being unexcreted 8 days after injection. The highest thallium accumulation was found in maternal muscle and brain tissues. Fetal brain exhibits higher thallium uptake and faster decay rate of thallium levels than maternal brain. It is suggested that the reduced activity of the mechanisms regulating ion movements and composition of nervous tissue and the immaturity of the blood-brain barrier play a role in the peculiar pattern of thallium kinetics in the developing rat brain.

Animals↗
PubMedDate not supplied

Quantitative thallium-201 myocardial exercise scintigraphy in normal subjects and patients with normal coronary arteries.

Quantitative thallium-201 myocardial exercise scintigraphy was tested in two patient populations representing alternative standards for cardiac normality: group I comprised 18 male uncatheterized patients with a low likelihood of coronary artery disease (CAD); group II contained 41 patients with normal coronary arteriograms. Group I patients were younger, they achieved a higher rate-pressure product than group II patients; all had normal findings by physical examination and electrocardiography at rest and exercise. Group II patients comprised 21 females, 11 patients showed abnormal electrocardiography at rest, and five patients showed ischemic ST depression during exercise. Twelve patients had signs of minimal CAD. Twelve patients revealed abnormal visual and quantitative thallium findings, three of these patients had minimal CAD. Profiles of uptake and washout of thallium-201 were derived from both patient groups, and compared with normal limits developed by Maddahi et al. Furthermore, low likelihood and angiographically normal patients may differ substantially, and both sets of normal patients should be considered when establishing criteria for abnormality in exercise thallium imaging. When commercial software containing normal limits for quantitative analysis of exercise thallium-201 imaging is used in clinical practice, it is mandatory to compare these with normal limits of uptake and washout of thallium-201, derived from the less heterogeneous group of low-likelihood subjects, which should be used in selecting a normal population to define normality.

Adult↗
PubMed1989

Relation between myocardial thallium-201 kinetics during exercise and quantitative coronary angiography in patients with one vessel coronary artery disease.

This study examined the relation between the kinetics of thallium-201 and coronary stenosis in 30 patients with one vessel coronary artery disease; 25 patients had no visible collateral vessels. The myocardial thallium concentration in the postexercise images and percent washout were determined in the distribution of the diseased vessel and a normal vessel, and each was expressed as a ratio. Coronary stenosis was assessed as minimal diameter stenosis, minimal area stenosis and percent diameter stenosis. The correlations between the myocardial concentration ratio or washout ratio and the descriptors of coronary stenosis improved when the patients with collateral vessels were excluded. There were significant correlations between the myocardial thallium concentration ratio and minimal diameter stenosis (r = 0.73, p less than 0.001), minimal area stenosis (r = 0.72, p less than 0.001) and, to a lesser degree, percent diameter stenosis (r = -0.51, p less than 0.01). Similarly, there were significant correlations between washout ratio and minimal diameter stenosis (r = 0.50, p less than 0.01) and minimal area stenosis (r = 0.45, p less than 0.02) but not percent diameter stenosis (r = 0.37, p = 0.06). Thus, variation in thallium kinetics in relation to the severity of coronary stenosis can be demonstrated with conventional imaging in patients with one vessel disease. The myocardial thallium concentration and washout are physiologic expressions of the severity of perfusion deficit and are dependent on collateral flow. The myocardial thallium concentration ratio and washout ratio correlate better with minimal diameter and area stenosis than with percent diameter stenosis.

Aged↗
PubMed1990

Prognostic value of dipyridamole thallium scintigraphy for evaluation of ischemic heart disease.

Exercise testing alone or in combination with thallium scintigraphy has significant prognostic value. In contrast, dipyridamole thallium imaging is not dependent on patients achieving adequate levels of exercise, but no long-term prognostic studies have been reported. Accordingly, imaging results of 516 consecutive patients referred for dipyridamole thallium studies were correlated with subsequent cardiac events, death (n = 23) and myocardial infarction (n = 43) over a mean follow-up period of 21 months. Patients with a history of congestive heart failure, prior myocardial infarction, diabetes mellitus or abnormal scans were significantly more likely to have a cardiac event (p less than 0.03). With use of logistic regression analysis, an abnormal scan was an independent and significant predictor of subsequent myocardial infarction or cardiac death and increased the relative risk of any event more than threefold. The presence of redistribution on thallium scanning further increased the risk of a cardiac event. Survival analysis demonstrated a significant difference between patients with an abnormal or normal thallium scan over a 30 month period. In conclusion, dipyridamole thallium scintigraphy demonstrates prognostic value in a large unselected population and may be an adequate clinical alternative to physiologic exercise testing in the evaluation of coronary heart disease.

Aged↗
PubMed1992

Comparison of technetium-99m sestamibi and thallium-201 retention characteristics in canine myocardium.

OBJECTIVES: The aim of this study was to compare the myocardial retention of technetium-99m (Tc-99m) sestamibi and thallium-201 over a wide range of blood flow at different time points after tracer injection. BACKGROUND: Technetium-99m sestamibi has been proposed as a new perfusion tracer with better physical characteristics than those of thallium-201 for scintigraphic imaging. However, no studies have simultaneously compared the ability of both tracers to assess myocardial blood flow during pharmacologic vasodilation. METHODS: The myocardial retention of Tc-99m sestamibi and thallium-201 were compared over a wide range of blood flow induced by regional coronary occlusion and dipyridamole infusion in an open chest dog model. Myocardial retention of both tracers was determined by in vitro tissue counting at 2, 5, and 20 min after tracer injection and was correlated with microsphere-determined blood flow. RESULTS: Thallium-201 demonstrated greater absolute tissue retention than did Tc-99m sestamibi. At 2 min after tracer injection, there was an almost linear relation between the retention of both tracers and myocardial blood flow over a wide flow range. However, this relation was not maintained over time. At 20 min after injection, the retention of both tracers underestimated myocardial blood flow at higher flow rates. At 2, 5 and 20 min after injection, increments of relative tracer retention between the different levels of flow were always greater for thallium-201 than for Tc-99m sestamibi. CONCLUSIONS: Thallium-201 displays more suitable physiologic characteristics as a flow tracer and may allow better differentiation of myocardial regions with different levels of coronary flow reserve. For both tracers, early cardiac imaging may minimize underestimation of blood flow at higher flow rates.

Animals↗
PubMed1993

Independent and incremental prognostic value of exercise single-photon emission computed tomographic (SPECT) thallium imaging in coronary artery disease.

OBJECTIVES: The objective of this study was to examine the independent and incremental prognostic value of exercise single-photon emission computed tomographic (SPECT) thallium imaging in patients with angiographically defined coronary artery disease. BACKGROUND: Previous studies showed the importance of exercise thallium-201 in risk stratification. However, most of these studies used planar imaging techniques. METHODS: Follow-up data were obtained in 316 medically treated patients with coronary artery disease. Cox proportional hazards regression models were used to examine the independent and incremental prognostic values of clinical, exercise, thallium and cardiac catheterization data. RESULTS: There were 35 events (cardiac death or nonfatal myocardial infarction) at a mean follow-up time of 28 months. Univariate analysis showed that gender (chi-square = 5.1), exercise work load (chi-square = 3.1), extent of coronary artery disease and left ventricular ejection fraction (chi-square = 14.8) and thallium variables (chi-square = 22.7) were prognostically important. The thallium data provided incremental prognostic value to catheterization data (chi-square = 33.7, p < 0.01). The extent of the perfusion abnormality was the single best predictor of prognosis (chi-square = 14). Patients with a large perfusion abnormality had a worse prognosis than that of patients with a mild or no abnormality (Mantel-Cox statistics = 10.6, p < 0.001). CONCLUSIONS: In medically treated patients with coronary artery disease, exercise SPECT thallium imaging provides independent and incremental prognostic information even when catheterization data are available. The extent of the perfusion abnormality is the single most important prognostic predictor.

Aged↗
PubMed1996

Prediction of recovery of myocardial dysfunction after revascularization. Comparison of fluorine-18 fluorodeoxyglucose/thallium-201 SPECT, thallium-201 stress-reinjection SPECT and dobutamine echocardiography.

OBJECTIVES: We compared three techniques to predict functional recovery after revascularization. BACKGROUND: Recently, fluorine-18 (F-18) fluorodeoxyglucose in combination with single-photon emission computed tomography (SPECT) has been proposed to identify viable myocardium, Thallium-201 reinjection and low dose dobutamine echocardiography are used routinely for this purpose. METHODS: Seventeen patients (mean [+/- SD] left ventricular ejection fraction 36 +/- 11%) were studied. Regional and global ventricular function were evaluated before and 3 months after revascularization by echocardiography and radionuclide ventriculography, respectively. Myocardial F-18 fluorodeoxyglucose uptake (during hyperinsulinemic glucose clamping) was compared with rest perfusion assessed with early thallium-201 SPECT. On a separate day, low dose dobutamine echocardiography and post-stress thallium-201 reinjection SPECT were simultaneously performed. RESULTS: The sensitivities for F-18 fluorodeoxyglucose/thallium-201, thallium-201 reinjection and low dose dobutamine echocardiography to assess recovery were 89%, 93% and 85%, respectively; specificities were 77%, 43% and 63%, respectively. Stepwise logistic regression indicated that F-18 fluorodeoxyglucose/ thallium-201 was the best predictor. In hypokinetic segments, the combination of F-18 fluorodeoxyglucose/thallium-201 and low dose dobutamine echocardiography was the best predictor. Global function improved (left ventricular ejection fraction increased > 5%) in 6 patients and remained unchanged in 11. All three techniques correctly identified five of six patients with improvement. Fluorine-18 fluorodeoxyglucose/thallium-201 identified all patients without improvement; low dose dobutamine echocardiography identified 9 of 11 without improvement; and thallium-201 reinjection identified 6 of 11 patients without improvement. CONCLUSIONS: Fluorine-18 fluorodeoxyglucose/thallium-201 SPECT was superior to the other techniques in assessing functional recovery. Integration of metabolic and functional data is necessary, particularly in hypokinesia, for optimal prediction of improvement of regional function.

Adult↗
PubMed1998

Prognostic value of exercise thallium-201 imaging in a community population.

BACKGROUND: The prognostic value of exercise thallium-201 imaging has been well established in referral patient populations at tertiary care centers, but these results may be influenced by referral bias. METHODS: This study was performed to evaluate the prognostic value of thallium imaging in a community-based population of 446 residents of Olmsted County, Minn. Eleven variables were prospectively selected and tested for their associations with outcome end points. RESULTS: Four variables (age, history of myocardial infarction, number of abnormal thallium segments on the postexercise images, and increased thallium lung uptake) contained the most independent prognostic information. For the end point overall mortality rate, the multivariate chi-square values were 17.2 (p < 0.0001) for age and 20.9 (p < 0.0001) for the number of abnormal thallium segments on the postexercise images. Five-year survival rate for patients older than the median age of 59 years with an abnormal scan was 84% versus 97% for patients < or = 59 years of age with a normal scan. CONCLUSION: Exercise thallium imaging was useful for prognostic purposes in this relatively low-risk community population, confirming the findings of referral population studies.

Adult↗
PubMed1996

Relation between contractile response of akinetic segments during dobutamine stress echocardiography and myocardial ischemia assessed by simultaneous thallium-201 single-photon emission computed tomography.

There are no standard criteria for the diagnosis of myocardial ischemia in akinetic segments during dobutamine stress echocardiography (DSE). The aim of the study was to assess the relation between different responses of akinetic segments during DSE and ischemia assessed by thallium-201 single-photon emission computed tomography (SPECT). Dobutamine-atropine stress echocardiography with simultaneous stress-reinjection thallium-201 SPECT was performed in 67 patients with old myocardial infarction significant and coronary artery stenosis. Fourteen myocardial segments were matched for both DSE and SPECT. Ischemia on SPECT was defined as reversible thallium defects. In 257 akinetic segments, 4 patterns during DSE were identified: (1) biphasic response in 41 segments (16%), defined as improvement at low dose (5 to 10 microgram/kg/min) followed by worsening at high dose; (2) persistent akinesia in 155 segments (60%); (3) akinesia becoming dyskinesia in 39 segments (15%); and (4) sustained improvement in 22 segments (9%). Reversible thallium defects were detected in 21 segments (51%) in group 1, in 20 segments (13%) in group 2, none in group 3, and in 2 segments in group 4 (9%). The prevalence of reversible defects in biphasic segments was higher compared with other patterns (p <0.00001 vs groups 2 and 3, p <0.005 vs group 4). The ischemic perfusion defect score was significantly higher in group 1 than group 2. The positive predictive value of biphasic response for reversible thallium defects was similar to that of stress-induced dyssynergia in normal segments at rest (51% vs 58%). It is concluded that of the various responses of akinetic segments to dobutamine infusion, the biphasic response is associated with the highest prevalence and greatest severity of ischemic on thallium SPECT. Observation of contractile response at both low- and high-dose DSE is a valuable approach for the diagnosis of myocardial ischemia in akinetic segments.

Aged↗