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Biomedical subjects

G V Heller

Publications and source records attributed to G V Heller.

At least 19 recordsLinked to original sources
PubMed1998

Influence of race on the prediction of cardiac events with stress technetium-99m sestamibi tomographic imaging in patients with stable angina pectoris.

The prognostic value of myocardial perfusion imaging in African-Americans is unknown. This study compared the prediction of cardiac events of stress technetium-99m (Tc-99m) sestamibi single-photon emission computed tomography (SPECT) imaging in symptomatic Caucasian and African-American patients. Prospectively collected stress Tc-99m sestamibi tomographic imaging data from 4 medical centers, with follow-up information in 1,086 Caucasian and African-American patients, were analyzed in a core statistical laboratory. Primary events of cardiac death and nonfatal myocardial infarction and secondary events of all-cause mortality were analyzed using Kaplan-Meier survival analysis and Cox proportional-hazards multivariable model. Normal images in both African-Americans and Caucasians were associated with a low-annual cardiac event rate, whereas abnormal images were significantly associated with a higher cardiac event rate. The highest predictor of cardiac events was multivessel abnormality in both races. Use of this technique could identify patients at high risk and potentially reduce the high-cardiac event rate in African-Americans by utilizing appropriate therapies.

Aged↗
PubMed1997

Direct comparison of arbutamine and dobutamine stress testing with myocardial perfusion imaging and echocardiography in patients with coronary artery disease.

Arbutamine, a new sympathomimetic compound, appears to elicit a more balanced inotropic and chronotropic response than dobutamine, currently used as a pharmacologic stress agent. The present study was performed to compare standard dobutamine stress testing with arbutamine for the detection of myocardial ischemia with technetium (Tc)-99m sestamibi tomographic imaging and 2-dimensional echocardiography in patients with coronary artery disease. Twenty-six patients with evidence of coronary artery disease underwent dobutamine infusion of 5 to 40 microg/kg/min in 3-minute stages. On a separate day, arbutamine was administered by an automated, computerized, closed-loop device monitoring both heart rate and blood pressure. Both infusions were terminated upon achievement of target heart rate, completion of maximal infusion dose (dobutamine), heart rate saturation (arbutamine), or standard clinical end points. Tc-99m sestamibi was injected before termination of both infusions followed by tomographic myocardial perfusion imaging, whereas echocardiography was performed at baseline and throughout the infusions. There were no significant differences in maximal heart rate, blood pressure, and rate-pressure product as well as in the development of anginal symptoms or electrocardiographic changes during both infusions. The location and severity of myocardial perfusion defects and echocardiographic wall motion abnormalities were similar between both agents. It is concluded that arbutamine produces similar imaging results compared with standard dobutamine stress with both Tc-99m sestamibi single-photon emission computed tomographic myocardial perfusion imaging and 2-dimensional echocardiography.

Adult↗
PubMed1997

Impact of acute propranolol administration on dobutamine-induced myocardial ischemia as evaluated by myocardial perfusion imaging and echocardiography.

Beta-blocker therapy may delay or completely prevent myocardial ischemia during exercise testing, as assessed by ST-segment shifts, myocardial perfusion defects, or echocardiographic wall motion abnormalities. However, the impact of beta-blocker therapy on these end points during dobutamine stress testing has not been well established. The purpose of this study was to determine the impact of propranolol on dobutamine stress testing with ST-segment monitoring, technetium-99m (Tc-99m) sestamibi single-photon emission computed tomography (SPECT) imaging, and echocardiography. In 17 patients with known reversible perfusion defects, dobutamine stress tests with and without propranolol were performed in randomized order and on separate days, following discontinuation of oral beta blockers and calcium antagonists. Propronolol was administered intravenously to a cumulative dose of 8 mg or to a maximum heart rate reduction of 25% and dobutamine was infused in graded doses in 3 minute stages until a standard clinical end point or the maximum dose of 40 microg/kg/min was achieved. The dobutamine stress test after propranolol was associated with a lower maximum heart rate (83 +/- 18 vs 125 +/- 17, p <0.001) and rate pressure product (14,169 +/- 4,248 vs 19,894 +/- 3,985, p <0.001) despite a higher infusion dose. The SPECT myocardial ischemia score was also lower (6.9 +/- 5.8 vs 10.1 +/- 7.1, p = 0.047) and fewer echocardiographic segments were abnormal (3.4 +/- 3.0 vs 4.6 +/- 3.4, p = 0.042). In 4 of 17 patients, reversible perfusion defects and echocardiographic wall motion abnormalities were detected during the control but not during the propranolol test. Thus, during dobutamine stress testing, beta-blocker therapy attenuates, and in some cases eliminates, evidence of myocardial ischemia.

Aged↗
PubMed1997

Prognostic importance of scintigraphic left ventricular cavity dilation during intravenous dipyridamole technetium-99m sestamibi myocardial tomographic imaging in predicting coronary events.

Left ventricular (LV) cavity dilation during stress myocardial perfusion imaging has been associated with multivessel disease, and may be an independent prognostic marker in addition to perfusion defects. The present study examines the predictive value for future cardiac events of transient or fixed LV dilation during dipyridamole technetium-99m (Tc-99m) sestamibi single-photon emission computed tomography (SPECT) imaging. The study included 512 consecutive patients who underwent SPECT imaging with Tc-99m sestamibi after dipyridamole infusion. Transient LV dilation was seen in 70 patients (14%) and 74 had fixed cavity dilation (14%); cavity size was normal in 368 patients (72%). Each perfusion scan was classified as normal or abnormal, and if abnormal, defects were categorized as transient or fixed, and as small, medium, or large (depending upon the number of abnormal vascular territories). Events during a mean follow-up of 12.8 +/- 6.8 months were tabulated by direct review of hospital charts and death certificates. The cardiac event rate (cardiac death or nonfatal infarction) was 1.9% in patients with normal cavity size, 11.4% with transient LV dilation, and 13.5% with fixed LV dilation (p < 0.01). Compared with patients with normal cavity size, those with transient LV dilation were more likely to sustain a myocardial infarction (p < 0.01) and those with fixed dilation more frequently suffered cardiac death (p < 0.01) and hospitalization for heart failure (p < 0.01). The group with the highest risk had both a large perfusion defect and cavity dilation. By Cox proportional hazard regression analysis, both transient and fixed LV dilation were strong independent predictors of cardiac events. Transient or fixed LV dilation are commonly seen during dipyridamole Tc-99m sestamibi SPECT imaging (14% incidence for each) and are useful predictors of cardiac events.

Aged↗
PubMed1997

Relation of gender to physician use of test results and to the prognostic value of stress technetium 99m sestamibi myocardial single-photon emission computed tomography scintigraphy.

We analyzed potential gender differences in the use and prognostic value of stress technetium 99m sestamibi tomography, image results, and cardiac event rates over a period of 15 +/- 8 months in 1226 men and 1151 women. Men had more abnormal tomographic images, but referral for catheterization and revascularization similarly increased in relation to the number of defects. Men and women with abnormal images had similar event rates, 19.6% and 18.2%, respectively, although men more often had myocardial infarction or cardiac death (7.6% vs 4.1 %, p < 0.05), whereas women had an increased likelihood of unstable angina or congestive heart failure (11.5% vs 7.6%, p < 0.05). Normal images predicted a low yearly rate of myocardial infarction or death: 1.7% for men and 0.8% for women. Image findings, particularly defect extent, were independent predictors of events in both groups. Thus, after stress Tc-99m sestamibi single-photon emission computed tomography perfusion imaging, there was no gender bias in referral for invasive procedures, and for both men and women image findings were strongly associated with prognostic outcome.

Angina Pectoris↗
PubMed1997

Safety of early intravenous dipyridamole technetium 99m sestamibi SPECT myocardial perfusion imaging after uncomplicated first myocardial infarction. Early Post MI IV Dipyridamole Study (EPIDS).

We assessed the safety of early (2 to 4 days) intravenous dipyridamole infusion in conjunction with technetium 99m sestamibi tomographic myocardial perfusion imaging in patients with first myocardial infarction (MI). Early risk stratification with myocardial perfusion imaging of patients after acute MI may be useful to identify patients who either require further evaluation or may be safely discharged. Because of minimal hemodynamic effects, intravenous dipyridamole may be a safe means of producing hyperemia for myocardial perfusion imaging. Stable patients with first acute MI who met entry criteria were randomized (3:1) to either intravenous dipyridamole infusion (0.56 mg/kg over a 4-minute period) 48 to 96 hours after onset of symptoms or a control (no test) group. Adverse cardiac events (unstable angina, recurrent MI, or cardiac death) were evaluated during and 24 hours after the dipyridamole infusion and during the corresponding 24 hours for the control group. Two hundred eighty-four patients received dipyridamole infusion a mean time of 3.3 +/- 0.7 days after MI. There were no adverse clinical events either during or immediately after the infusion. During the 24 hours after infusion, three patients had symptoms of unstable angina pectoris, one patient had a recurrent MI, and no patients died. The earliest event occurred 4.2 hours after the dipyridamole infusion. Three patients had unstable angina pectoris, whereas no patients had either recurrent MI or died in the control group. There were no statistically significant differences between the two groups. In a multicenter trial, dipyridamole infusion administered early after the first acute MI resulted in no increased evidence of cardiac events either immediately or 24 hours after the procedure compared with a control group. Therefore intravenous dipyridamole can be safely used as a pharmacologic vasodilator for myocardial perfusion imaging soon after uncomplicated MI.

Angina, Unstable↗
PubMed1997

Recent developments in the prognostic use of myocardial perfusion imaging.

Stress myocardial perfusion imaging has become a mainstay in the noninvasive assessment of patients with known or suspected coronary artery disease for several compelling reasons. Radionuclide myocardial perfusion imaging can be performed using a variety of stressors, including exercise, pharmacologic stress (including dipyridamole, adenosine, dobutamine, and arbutamine), or a combination of exercise and pharmacologic stress. The combination of exercise and pharmacologic stress allows an assessment of the patient's exercise tolerance, to be performed while adequately stressing him or her pharmacologically. Radiopharmaceutical choice has been expanded to include not only thallium-201 but also technetium-based imaging agents such as sestamibi and tetrofosmin. The use of technetium imaging agents has recently been enhanced by the ability to assess ventricular function using gated single-photon emission computed tomography (SPECT) imaging techniques. Finally, the ability to provide prognostic information in the same patients has led to incremental clinical use.

Clinical Trials as Topic↗
PubMed1997

Clinical comparison of circular versus noncircular acquisition using technetium-99m myocardial perfusion SPECT imaging.

UNLABELLED: The optimal orbit for myocardial SPECT imaging has not yet been determined. In order to evaluate differences in image quality and reader interpretation between orbiting methods, 50 patients scheduled for routine stress/rest 99mTc-sestamibi imaging had both a circular and a noncircular study using an ADAC Vertex dual-head imaging system. METHODS: Each study was acquired using a 64 x 64 matrix, 64 stops at 25 sec per stop. Images were processed using a Butterworth filter with a frequency cutoff of 0.6 and an order of 5.0. Studies were interpreted by three experienced readers without knowledge of patient name or orbiting technique for normal and abnormal segments and overall image quality. RESULTS: There was no significant difference in the semi-quantitative assessment of either defect extent or reversibility or in the quantitative assessment of defect size between the two types of orbits. However, while all 50 noncircular studies were read as good or fair quality, 23 circular studies were read as fair or poor (p = < 0.0002). CONCLUSION: Qualitative and quantitative analysis revealed similar size and extent of perfusion defects using either circular or noncircular orbit, but images with the noncircular orbit were of significantly better image quality and may be preferable to a circular orbit with 99mTc-sestamibi.

Adrenergic beta-Agonists↗
PubMed1996

Relation between perfusion defects on stress technetium-99m sestamibi SPECT scintigraphy and the location of a subsequent acute myocardial infarction.

Although the presence of perfusion defects on stress myocardial perfusion imaging has been shown to correlate with future cardiac events, including acute myocardial infarction (AMI), it is unknown whether the location of the AMI can be predicted. Therefore, for 25 patients who had an AMI following a stress technetium-99m sestamibi single-photon emission computed tomographic (SPECT) imaging study and whose infarct location could be determined, the territory of infarction was correlated with the location of previous myocardial perfusion defects. A SPECT perfusion defect had been present in 24 patients (96%). The AMI occurred in territories that showed a reversible defect in 14 patients (56%), whereas 3 infarctions (12%) were in territories that revealed a fixed defect, and 8 infarctions (32%) were in territories that had not shown a defect on prior SPECT imaging. Whereas the incidence of infarction in territories with a reversible defect was highest at 14 of 26 (54%), the incidence of infarction in territories with a fixed defect was 3 of 7 (43%), and in territories with no defect was 8 of 42 (19%) (p = 0.011). Neither the time interval between SPECT imaging and infarction, nor the perfusion defect severity, was related to the correlation between perfusion defect and infarct location. Thus, although AMI occurs most often at the site of previous perfusion defects, reversible or fixed, a substantial percentage occur in territories without a perfusion defect. These findings suggest that abnormalities on SPECT perfusion imaging, although they serve as markers of significant coronary disease and increase the likelihood of infarction, do not always predict the exact location of infarction.

Aged↗
PubMed1996

The role of cardiac imaging and biochemical markers in patients with acute chest pain.

Acute chest pain syndromes are common, with over 6 million patients in the United States presenting to emergency departments with suggestive symptoms. This review concentrates on the previous models and new diagnostic testing procedures. The different modalities emphasized are computer-generated models, serum markers, echocardiography, and nuclear imaging in the emergency department. The use of new markers and imaging may help to risk-stratify patients earlier for potential treatment and triage decisions.

Biomarkers↗
PubMed1996

Pharmacological stress testing with technetium-99m single-photon emission computerized tomography imaging in the preoperative assessment of patients undergoing noncardiac surgery.

Pharmacological stress testing with Tc-99m sestamibi is being used extensively for the diagnosis of coronary disease. Although there are no randomized and prospective studies using this technique for preoperative evaluation of patients undergoing noncardiac surgery, there are several studies that indicate that it is equivalent to exercise perfusion imaging and can be used for evaluating the prognosis of patients with coronary artery disease (CAD). This review will discuss these studies.

Coronary Disease↗
PubMed1996

Myocardial perfusion imaging during chest pain: a useful clinical tool.

A 72-year old man was injected with Tc 99m tetrofosmin during acute chest pain, in the presence of a nondiagnostic electrocardiogram (ECG). Myocardial perfusion imaging revealed a large anteroseptal defect. Subsequent catheterization confirmed left anterior descending artery disease. Acute imaging may be useful in the identification of critical disease in patients with chest pain and nondiagnostic ECG.

Aged↗
PubMed1995

Independent prognostic value of intravenous dipyridamole with technetium-99m sestamibi tomographic imaging in predicting cardiac events and cardiac-related hospital admissions.

OBJECTIVES: This study sought to establish the prognostic value of intravenous dipyridamole technetium-99m (Tc-99m) sestamibi single-photon emission computed tomographic (SPECT) myocardial perfusion imaging. BACKGROUND: Optimal management of patients with coronary artery disease involves strategies designed to reduce the risk of myocardial infarction and cardiac death. The role of myocardial perfusion imaging using newer clinical techniques to determine risk and possible benefit from therapy has not been evaluated. METHODS: Myocardial imaging results were classified as normal or abnormal (fixed or reversible defects; small, moderate or large). Follow-up evaluation of all patients included the occurrence of cardiac death or nonfatal myocardial infarction and other cardiac-related hospital admissions. RESULTS: During a mean (+/- SD) follow-up period of 12.8 +/- 6.8 months in 512 patients, 25 had a cardiac event. Patients with abnormal perfusion had significantly more cardiac events than those with normal perfusion (22 vs. 3, p < 0.01). Patients with reversible defects had the highest event rates (8.6%), and those with normal study results had a very low event rate (1.4%). Large defects were strongly associated with more cardiac events and hospital admissions than either normal scan results or abnormal results showing small defects. CONCLUSIONS: Patients with normal study results or a small defect after intravenous dipyridamole Tc-99m sestamibi SPECT imaging had an excellent short-term prognosis. Those with abnormal results (reversible or large defect) had an increased risk of subsequent cardiac death, nonfatal myocardial infarction and other cardiac-related hospital admissions.

Adult↗
PubMed1995

Use of exercise technetium-99m sestamibi SPECT imaging to detect residual ischemia and for risk stratification after acute myocardial infarction.

The clinical presentation, electrocardiographic findings, and technetium-99m sestamibi single-photon emission computed tomography (SPECT) imaging results of 134 consecutive patients who underwent nuclear exercise testing within 14 days of an acute myocardial infarction (AMI) were correlated with cardiac events over a 15 +/- 10-month follow-up. Whereas only 23 patients (17%) had chest pain and 31 (23%) had ischemic ST-segment depression during exercise, 94 (70%) had ischemia on SPECT (p < 0.001). On follow-up, 13 patients experienced a cardiac event: 7 were rehospitalized for unstable angina, 3 had recurrent AMI, and 3 died of cardiac causes. Ischemia on the sestamibi images identified 11 of these patients (85%), whereas chest pain identified only 3 (23%, p = 0.006), and electrocardiographic ischemia identified only 4 (31%, p = 0.017). The presence of either ischemia as seen on SPECT or defects in multiple vascular territories identified 12 patients (92%) with an event, including all who had cardiac death. By Cox regression analysis of clinical, stress, and image parameters, the number of ischemic defects on SPECT was the only significant correlate of a future event (chi-square = 4.62, p = 0.03), and patients with > or = 3 reversible sestamibi defects had an event rate of 38%. The extent of ischemia as seen on nuclear imaging remained a strong correlate (p = 0.008) of an event in the 54 patients (40%) who had received thrombolytic therapy. Thus, exercise technetium-99m sestamibi SPECT after AMI frequently reveals residual ischemia, and is better than clinical data, symptoms, and stress electrocardiographic data in identifying patients who will have a subsequent cardiac event.

Aged↗
PubMed1994

Comparison of dobutamine and exercise using technetium-99m sestamibi imaging for the evaluation of coronary artery disease.

Studies using dobutamine thallium-201 myocardial perfusion imaging have suggested a high sensitivity and specificity for the detection of coronary artery disease. However, few data are available comparing dobutamine with exercise stress for the detection and localization of perfusion defects. This study compared the effects of dobutamine and exercise stress using technetium-99m sestamibi single-photon emission computed tomographic imaging in the same patients in a prospective crossover trial. Twenty-four patients with a high likelihood of coronary artery disease underwent tomographic myocardial imaging at rest, after symptom-limited treadmill exercise, and after intravenous dobutamine (maximum 30 micrograms/kg/min). Tomograms of the left ventricle were divided into 20 segments and were interpreted without knowledge of patient identity or stress protocol. Dobutamine was well tolerated by all patients. Segment-by-segment concordance between exercise and dobutamine images was highly significant (kappa = 0.56, p < 0.0001). Global first-order agreement (normal vs abnormal) between exercise and dobutamine studies was 96% (kappa = 0.65, p = 0.02); global second-order agreement (normal vs fixed vs ischemic defect) was 88% (kappa = 0.45, p = 0.02). Regional first- and second-order agreement were 96 and 93%, respectively (p < 0.001 for both). Twenty patients underwent coronary angiography. Comparisons between exercise and angiography and between dobutamine and angiography were similar for both global agreement (95 vs 100%, p = NS) and regional agreement (77 vs 72%, p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists↗
PubMed1994

Prevalence of right ventricular perfusion defects after inferior myocardial infarction assessed by low-level exercise with technetium 99m sestamibi tomographic myocardial imaging.

To assess the prevalence of right ventricular perfusion defects after a recent inferior wall myocardial infarction, 33 patients were studied 6 to 14 days after infarction with low-level exercise testing and technetium 99m (99mTc) sestamibi (SPECT) imaging. Twenty-two control subjects with a < 5% likelihood of coronary artery disease undergoing exercise 99mTc sestamibi imaging were also studied. For each image the right ventricle was computer isolated from reconstructed transverse cardiac slices, followed by reorientation into oblique slices. Both right and left ventricular images were visually assessed for defects. A quantitative method of defect detection was also applied to the right ventricle. For the right ventricle, 100% of the stress images and 96% of the rest images were adequate for interpretation. Right ventricular stress perfusion defects were identified in 10 (30%) of 33 patients with recent inferior infarction, with 50% completely or partially normalizing on rest images, consistent with ischemia. Of 14 patients with left ventricular inferoseptal defects, eight (57%) had right ventricular defects compared with 2 (11%) of 19 without inferoseptal defects (p < 0.005). We concluded that the right ventricle can be adequately assessed for perfusion defects by means of exercise with 99mTc sestamibi SPECT imaging. Defects of the right ventricle after inferior myocardial infarction occur frequently, and many have evidence of ischemia. Right ventricular perfusion defects are closely associated with left ventricular inferoseptal defects.

Case-Control Studies↗