Assessment of myocardial viability in patients with chronic coronary artery disease. Rest-4-hour-24-hour 201Tl tomography versus dobutamine echocardiography.

Background: To date, late redistribution after resting 201Tl injection has not been evaluated. In addition, the concordance between resting 201Tl imaging and dobutamine echocardiography in identifying viable myocardium has not been assessed.

Methods And Results: Forty patients with coronary artery disease underwent rest-4-hour-24-hour 201Tl tomography and dobutamine echocardiography (5 to 10 micrograms.

Prolonged impairment of regional contractile function after resolution of exercise-induced angina. Evidence of myocardial stunning in patients with coronary artery disease.

Background: Delayed recovery of contractile function in spite of normal perfusion (ie, "stunning") has been described in animal models of exercise-induced myocardial ischemia. Therefore, we investigated whether stunning may result from effort angina in patients.

Methods And Results: Patients with coronary artery disease underwent exercise testing combined with quantitative measurements of contractile function for up to 240 minutes after exercise determined by either measurement of regional ejection fraction (99mTc radionuclide angiography; n = 17, group A) or computer-assisted measurement of systolic wall thickening (n = 14, group B).

Inotropic stimulation by dobutamine increases left ventricular regional function at the expense of metabolism in hibernating myocardium.

The mechanism by which dobutamine increases the contraction of chronically dysfunctional myocardium and its effects on metabolism are still unknown. The aim of this study was to assess regional myocardial metabolism at rest and during an intracoronary dobutamine infusion in patients with hibernating myocardium. Eleven asymptomatic patients with single proximal stenosis of the left anterior descending coronary artery and persistent left ventricular dysfunction at rest (undergoing percutaneous transluminal coronary angioplasty [PTCA]) were studied prospectively.

Effects of diltiazem on left ventricular systolic and diastolic function in hypertrophic cardiomyopathy.

Hypertrophic cardiomyopathy (HC) is characterized by impaired diastolic function, and left ventricular (LV) outflow tract obstruction in about one-fourth of patients. Verapamil improves diastolic properties, but may have dangerous adverse effects. This study investigates the effects of diltiazem on hemodynamics and LV function in 16 patients with HC who were studied with cardiac catheterization and simultaneous radionuclide angiography.

Left ventricular systolic and diastolic function in severe obesity: a radionuclide study.

To verify the impact of sever obesity (defined as body mass index > 31 kg/m2) on left ventricular (LV) function, 32 asymptomatic obese but otherwise healthy subjects (16 men; age 38 +/- 11 years) voluntarily underwent first-pass and equilibrium 99mTc radionuclide angiography at rest and, in 22 of them, during bicycle supine exercise. Data were compared to those obtained from 10 normal volunteers (age 48 +/- 13; p < 0.05, vs.

Effects of dual-chamber pacing in hypertrophic cardiomyopathy on left ventricular outflow tract obstruction and on diastolic function.

Hypertrophic cardiomyopathy (HC) is characterized by impaired diastolic function and, in about 1/4 of patients, left ventricular (LV) outflow tract obstruction. Atrioventricular (AV) pacing diminishes LV outflow tract gradient in HC, but impairs diastolic function in the experimental animal and in different categories of patients. To investigate the effects of AV pacing on hemodynamics and LV function in obstructive HC, 16 patients with HC were studied by cardiac catheterization and simultaneous radionuclide angiography during atrial and AV pacing.

Dobutamine echocardiography predicts improvement of hypoperfused dysfunctional myocardium after revascularization in patients with coronary artery disease.

Background: In patients with coronary artery disease, dysfunctional hypoperfused myocardium at rest may represent either necrotic or viable hibernating myocardium. The accuracy of inotropic stimulation in identifying hypoperfused, reversibly dysfunctional myocardium has not been extensively investigated.

Methods And Results: Eighteen patients with stable chronic coronary artery disease underwent, while off drugs, quantitative 201Tl single-photon emission computed tomography after rest injection (2 to 3 mCi), two-dimensional echocardiography at rest and during dobutamine (5 to 10 micrograms/kg per minute i.

[Coronary angioplasty for the recovery of myocardial function after acute myocardial infarction: mid- and long-term results].

Sixty-three patients with previous myocardial infarction and documented hypoperfused reversibly dysfunctional myocardium after 201thallium tomography and/or echo-dobutamine were candidates to coronary angioplasty. Patients were enrolled at four hospitals (Naples, Milan, Pisa and Varese) and evaluated by different study protocols, while endpoint (presence of myocardial viability and efficacy of coronary angioplasty to improve dysfunctional myocardium) was similar. Sixty-two patients underwent successful angioplasty, and early evaluation (between 1 and 3 months after procedure) showed the ability of either 201thallium tomography and/or dobutamine echocardiography, to identify hypoperfused reversibly dysfunctional myocardium.

Improvement of the age-related impairment in left ventricular diastolic filling with verapamil in the normal human heart.

Background: Left ventricular (LV) diastolic function declines with the normal aging process. Because these changes are related to impaired active LV relaxation as well as to structural alterations, we hypothesized that verapamil might improve LV filling in elderly normal subjects compared with young normal subjects.

Methods And Results: We studied 27 normal volunteers (between 20 and 71 years old), with normal exercise tests and echocardiograms, by radionuclide angiography before and after 3 to 4 days of oral verapamil therapy.

Clinical significance of reduced regional myocardial glucose uptake in regions with normal blood flow in patients with chronic coronary artery disease.

Objectives: The objective of this study was to assess the clinical significance of reduced regional fluorine-18 (18F) fluorodeoxyglucose uptake with normal flow in patients with chronic coronary artery disease.

Background: In patients with ischemic left ventricular dysfunction, 18F-fluorodeoxyglucose uptake may be reduced in some myocardial regions despite normal flow. The significance of this finding is unclear and has not been investigated systematically.

Thallium reinjection demonstrates viable myocardium in regions with reverse redistribution.

Background: The clinical significance and pathophysiological mechanisms of reverse redistribution on stress-redistribution thallium-201 myocardial scintigraphy in patients with chronic coronary artery disease are unclear. Recent studies have shown that thallium-201 reinjection is a useful technique for the detection of myocardial viability in chronic coronary artery disease. In this investigation we determined whether thallium reinjection distinguishes viable from nonviable myocardium in regions with reverse redistribution.

Concordance and discordance between stress-redistribution-reinjection and rest-redistribution thallium imaging for assessing viable myocardium. Comparison with metabolic activity by positron emission tomography.

Background: Stress thallium scintigraphy provides important diagnostic and prognostic information in patients with coronary artery disease by demonstrating regional myocardial ischemia. However, if the clinical question being addressed is whether a region is viable and not whether there is inducible ischemia, then it may be more reasonable to perform rest-redistribution imaging rather than stress-redistribution imaging followed by either reinjection or late redistribution. Therefore, we determined whether stress-redistribution-reinjection and rest-redistribution imaging provide the same information regarding myocardial viability.

Regional systolic function, myocardial blood flow and glucose uptake at rest in hypertrophic cardiomyopathy.

Decreased 18fluorodeoxyglucose (FDG) uptake and blood flow at rest in the ventricular septum, as compared with the lateral wall, have been reported in mildly symptomatic patients with hypertrophic cardiomyopathy (HC). To assess whether regional metabolic heterogeneity in patients with HC is related to heterogeneous regional systolic function, 10 symptomatic patients (mean age 36 +/- 17 years) with HC and no coronary artery disease underwent positron emission tomography with oxygen-15-water and FDG, and nuclear magnetic resonance imaging at rest to assess regional anatomy and systolic function. Regional absolute blood flow was similar between the ventricular septum and lateral wall.

Hibernating and stunned myocardium.

The term "hibernating" myocardium has been introduced to indicate the presence of regional asynergy due to persistent hypoperfusion, which can be reversed after revascularization. The mechanisms underlying the prolonged functional adaptation of myocardial cells to hypoperfusion are still not clear, although preliminary experimental data indicate that a reduced availability of intracellular Ca++ may play an important role. The identification of hibernating myocardium may have therapeutic implications, since it has been demonstrated that the revascularization of hibernating myocardial territories may lead to regional and global improvement of systolic left ventricular function.

Effects of induced asynchrony on left ventricular diastolic function in patients with coronary artery disease.

Objectives: This study was designed to increase asynchrony with sequential atrioventricular (AV) pacing and to study its effects on left ventricular isovolumetric relaxation, rapid filling and stiffness.

Background: Left ventricular nonuniformity is a major determinant of diastolic function.

Methods: Thirteen patients with coronary artery disease were studied by simultaneous equilibrium radionuclide angiography and cardiac catheterization during atrial and AV pacing.

Comparison of left ventricular function in insulin- and non-insulin-dependent diabetes mellitus.

Diabetes mellitus has been reported to have controversial effects on left ventricular (LV) function in patients with no evidence of coronary artery disease. In this study, LV function at rest was evaluated in 2 groups of diabetic patients, with insulin-dependent (IDD; n = 16) and non-insulin-dependent (NIDD; n = 23) diabetes mellitus, with no evidence of coronary artery disease. All patients underwent an electrocardiographic stress test, and first-pass and equilibrium radionuclide angiography at rest and during supine exercise.

Three-dimensional registration of cardiac positron emission tomography attenuation scans.

A method is described and tested which allows three-dimensional registration of two cardiac PET attenuation scans of the same subject acquired at different times. The alignment method is based on maximizing the correlation coefficient between the stacks of slices obtained during each of the two imaging sessions. The method appears accurate to better than 1 mm in x, y and z, and better than 1.

Regional left ventricular wall thickening. Relation to regional uptake of 18fluorodeoxyglucose and 201Tl in patients with chronic coronary artery disease and left ventricular dysfunction.

Background: In previous studies comparing regional 201Tl (201Tl) and 18fluorodeoxyglucose (FDG) activity in patients with chronic coronary artery disease and left ventricular dysfunction, we hypothesized that regions with mild-to-moderate reduction in FDG activity and regions with mild-to-moderate irreversible 201Tl defects after 3- to 4-hour redistribution represent viable myocardium. In the present study, regional FDG and 201Tl activities were compared with regional systolic wall thickening by gated magnetic resonance imaging (MRI) to confirm the presence of viable myocardium in these territories.

Methods And Results: Twenty-five patients with chronic stable coronary artery disease and left ventricular dysfunction (ejection fraction, 28 +/- 10) underwent exercise 201Tl tomographic imaging (SPECT), using a reinjection protocol, positron emission tomography (PET) with FDG and H2(15)O, and gated MRI.

Metabolic evidence of viable myocardium in regions with reduced wall thickness and absent wall thickening in patients with chronic ischemic left ventricular dysfunction.

Reduced end-diastolic wall thickness with absent systolic wall thickening has been reported to represent nonviable myocardium in patients with chronic coronary artery disease. To assess whether reduced regional end-diastolic wall thickness and absent wall thickening accurately identify nonviable myocardium, 25 patients with ischemic left ventricular dysfunction (ejection fraction at rest 27 +/- 10%) underwent positron emission tomography with oxygen-15-labeled water and 18fluorodeoxyglucose to assess metabolic activity and spin-echo gated nuclear magnetic resonance imaging to measure regional end-diastolic wall thickness and wall thickening. The presence of metabolic activity was defined as 18fluorodeoxyglucose uptake (corrected for partial volume) greater than 50% of that in normal regions.

Effects of regional systolic asynchrony on left ventricular global diastolic function in patients with coronary artery disease.

Patients with coronary artery disease often have impaired left ventricular diastolic filling despite normal global systolic function. The influence of regional systolic asynchrony on diastolic function was assessed by radionuclide angiography in 60 patients with coronary artery disease and normal ejection fraction at rest: group 1 (n = 30) with normal wall motion at rest and group 2 (n = 30) with abnormal wall motion. Data were compared with those obtained from 19 normal volunteers.

Regional thallium uptake in irreversible defects. Magnitude of change in thallium activity after reinjection distinguishes viable from nonviable myocardium.

Background: Thallium reinjection immediately after stress-redistribution imaging identifies ischemic but viable myocardium in as many as 50% of the regions characterized by conventional redistribution imaging as irreversibly injured. However, we have previously shown that some regions in which irreversible defects persist despite reinjection are metabolically active, and hence viable, by positron emission tomography. In the current study, we determined whether the severity of reduction in thallium activity within irreversible defects on redistribution images and the magnitude of change in regional thallium activity after reinjection can further discriminate viable from nonviable myocardium in such defects.

Comparison of exercise radionuclide angiography with thallium SPECT imaging for detection of significant narrowing of the left circumflex coronary artery.

Although quantitation of exercise thallium tomograms has enhanced the noninvasive diagnosis and localization of coronary artery disease, the detection of stenosis of the left circumflex coronary artery remains suboptimal. Because posterolateral regional wall motion during exercise is well assessed by radionuclide angiography, this study determined whether regional dysfunction of the posterolateral wall during exercise radionuclide angiography is more sensitive in identifying left circumflex disease than thallium perfusion abnormalities assessed by single-photon emission computed tomography (SPECT). One hundred ten consecutive patients with CAD were studied, of whom 70 had a significant stenosis of the left circumflex coronary artery or a major obtuse marginal branch.

[Identification of viable myocardium in patients with chronic ischemic disease and left ventricular dysfunction: correlations between blood flow, metabolic activity and regional function].

To identify the presence of viable myocardium in areas of severe systolic dysfunction, we studied 22 patients (age 45 to 78 years) with chronic coronary artery disease and left ventricular dysfunction (mean ejection fraction 29 +/- 9%). All subjects underwent thallium-201 single photon emission computed tomography (SPECT), using the reinjection technique, positron emission tomography (PET) with H2(15)O and 18-fluorodeoxyglucose (FDG) to measure regional blood flow and exogenous glucose uptake, respectively, and nuclear magnetic resonance imaging (MRI). From matched transaxial PET, SPECT and MRI tomograms, a total of 290 left ventricular myocardial regions were analyzed.