sodium-pertechnetate-tc-99m and Myocardial-Ischemia

Eighteen patients with chronic renal failure had their cardiac status monitored during hemodialysis (HD). Ten studies were carried out using an ambulatory nuclear vest to assess ejection fraction (EF), heart rate (HR), relative end-systolic (ESV) and end-diastolic (EDV) volumes every 60 s. A total of 36 episodes of EF falls occurred in 9 patients, all asymptomatic. These EF falls were associated with a rise in ESV, while HR, BP, and EDV remained unchanged. The EF falls correlated best with the volume of ultrafiltrate removed. Ten patients had on-line ST-segment monitoring with sestamibi injection either at the time of ST depression (STD) or at the end of dialysis, if no STD occurred, in order to detect the presence of transient ischemia. Seven of ten patients had perfusion defects after dialysis, with STD occurring in 3 of 10 patients. Predialysis imaging was available in only 8 of 10 patients, and 6 of these patients had perfusion defects. Changes in perfusion defects were not significantly different in the 3 patients with STD compared with those without STD. EF falls and perfusion defects are common in HD patients even in the absence of known coronary artery disease; however, ST segment monitoring is not a sensitive tool for its detection. These changes in function and perfusion may represent myocardial ischemia and contribute to the high incidence of cardiovascular morbidity and mortality in this patient population.

Topics: Electrocardiography; Female; Heart; Humans; Kidney Failure, Chronic; Male; Middle Aged; Monitoring, Physiologic; Myocardial Ischemia; Radionuclide Ventriculography; Renal Dialysis; Signal Processing, Computer-Assisted; Sodium Pertechnetate Tc 99m; Technetium Tc 99m Sestamibi; Tomography, Emission-Computed, Single-Photon; Ventricular Function, Left

To understand the effect of hyperventilation (HV) stress in patients with spastic angina, left ventricular (LV) contraction was analyzed by quantitative phase analysis. The study was performed on 36 patients with spastic angina pectoris, including vasospastic angina pectoris (VspAP: 16 patients) and variant angina pectoris (VAP: 20 patients). First-pass radionuclide ventriculography (first-pass RNV) was performed at rest and after HV stress, and standard deviation of the LV phase distribution (SD) was analyzed. The SD was lower in patients with VspAP than in VAP (12.8+/-1.4 degrees vs. 14.6+/-2.2 degrees, p < 0.005) at rest. After HV stress, the SD (HVSD) tended to increase in VspAP patients (62.5%), whereas the SD decreased in VAP patients (70%). Due to HV stress, the percentage change in SD (%SD) in VspAP patients was 8.9+/-23.7% whereas that in VAP patients was -9.1+/-17.3% (p < 0.01). Moreover, phase histograms were divided into HVSD increase and HVSD decrease groups. The HVSD increase group had a decrease of HVEF, but the HVSD decrease group tended to have more decreased HVEF than the HVSD increase group. These results indicate that spastic angina pectoris patients show various responses to HV stress. The HVSD increase group might have additional myocardial ischemia due to regional coronary spasm. In contrast, in the HVSD decrease group severe LV dysfunction or diffuse wall motion abnormality might have been generated, and this caused a reduction in the SD value. Phase analysis would therefore add new information regarding electrocardiographically silent myocardial ischemia due to coronary spasm, and HV stress might increase sensitivity for the detection of abnormalities in quantitative phase analysis, especially in VspAP patients.

Topics: Adult; Aged; Angina Pectoris, Variant; Exercise Test; Female; Heart; Humans; Hyperventilation; Male; Middle Aged; Myocardial Ischemia; Sodium Pertechnetate Tc 99m; Ventricular Function; Ventriculography, First-Pass

The aim of this study was to compare three automatic programs (P1, P2, P3) for evaluating radionuclide left ventricular ejection fraction (LVEF) and to emphasize the clinical consequences. Gated radionuclide ventriculography was performed in 73 subjects, 15 of whom were healthy and 58 of whom had experienced heart failure. All scintigraphic data were processed with the three programs. Good inter-observer, intra-observer and automatic-manual reproducibility were observed using each of the three programs. On the other hand, in the normal subjects, the three mean normal LVEF values were significantly different from each other (P1 = 77 +/- 5%, P2 = 63 +/- 7%, P3 = 68 +/- 8%; P < 0.0001) In the pathological patients, the values obtained with P2 were significantly different from those obtained using P1 and P3 (P1= 32 +/- 15%, P2 = 26 +/- 13%; P < 0.0001), Moreover, the linear regression studies between the three automatic programs were always significantly different from the identity line equation (y = x). This study shows that LVEF criteria for normality depend on the program used, and inter-program measurement of LVEF is poorly reproducible. Caution is recommended when comparing data obtained from different centres (or different computers), either in the follow-up of a given patient or in gathering results from patient groups.

Topics: Adult; Aged; Aged, 80 and over; Analysis of Variance; Automation; Cardiomyopathies; Case-Control Studies; Heart Failure; Humans; Middle Aged; Myocardial Ischemia; Observer Variation; Regression Analysis; Reproducibility of Results; Sodium Pertechnetate Tc 99m; Stroke Volume; Tomography, Emission-Computed; Ventricular Function, Left

The purpose of this study was to determine the correspondence of mental stress-induced ischemia in the laboratory with ambulatory ischemia and to assess the relationship between hemodynamic responses to mental stress and the occurrence of ischemia. Although exercise testing is usually used to elicit myocardial ischemia, ischemia during daily life usually occurs at relatively low heart rates and in the absence of strenuous physical exercise. Mental stress has been shown to trigger ischemic events in the laboratory at lower heart rates but at blood pressures comparable to exercise. We therefore compared the extent to which mental stress and exercise testing identify patients who develop ischemia out of hospital.. One hundred thirty-two patients with documented coronary disease and recent evidence of exercise-induced myocardial ischemia underwent 48-hour ambulatory monitoring and radionuclide ventriculography during exercise and mental stress testing. Patients who displayed mental stress-induced ischemia in the laboratory were more likely to exhibit ischemia during daily life (P < .021). Furthermore, patients who exhibited ischemia during ambulatory monitoring displayed larger diastolic blood pressure (P < .006), heart rate (P < .039), and rate-pressure product responses (P < .018) during mental stress.. Among patients with prior positive exercise stress tests, mental stress-induced ischemia, defined by new wall motion abnormalities, predicts daily ischemia independent of exercise-induced ischemia. Exaggerated hemodynamic responses during mental stress testing also identify individuals who are more likely to exhibit myocardial ischemia during daily life and mental stress.

Topics: Activities of Daily Living; Coronary Disease; Electrocardiography, Ambulatory; Erythrocytes; Exercise Test; Female; Gated Blood-Pool Imaging; Hemodynamics; Humans; Male; Middle Aged; Myocardial Ischemia; Sodium Pertechnetate Tc 99m; Stress, Psychological

Experimental data have indicated that [99mTc]-nitroimidazole (BMS-181321) is preferentially taken up in hypoxic tissue; its kinetics, however, has not been fully investigated. The purpose of this study was to address the relation between perfusate oxygen level and myocardial retention of [99mTc]nitroimidazole.. Bolus injection and constant infusion experiments were performed in Langendorff buffer-perfused rat hearts in normoxic and hypoxic conditions. Data were acquired with a pair of NaI detectors. The initial clearance rate of [99mTc]nitroimidazole was approximately 20 seconds and independent of perfusate oxygen level. The slow clearance rate was greater than 3 hours in all perfusion conditions. The tissue retention of [99mTc]nitroimidazole varied from 0.61 +/- 0.14% in normoxic conditions to 5.94 +/- 1.16% in the most severe hypoxic conditions. In addition, tissue retention was inversely proportional to perfusate oxygen level in a sigmoidal manner. The constant infusion experiments established that the binding rate at 25% oxygen level (1.94 +/- 0.38 mL of perfusate/min-g dry wt) was twofold of that at 40% and sevenfold at 100%. The binding rate of [99mTc]nitroimidazole was independent of the perfusion sequence, suggesting irreversible binding.. These data indicate that [99mTc]nitroimidazole may be a useful tracer for the identification of myocardial hypoxia. A sigmoidal relation was demonstrated for the uptake of the tracer, which suggests that a threshold level of hypoxia is necessary for the uptake of the tracer.

Topics: Animals; Cell Hypoxia; Heart; Male; Myocardial Ischemia; Myocardium; Nitroimidazoles; Organotechnetium Compounds; Oxygen Consumption; Perfusion; Radionuclide Imaging; Rats; Rats, Sprague-Dawley; Sodium Pertechnetate Tc 99m; Technetium Tc 99m Pentetate; Time Factors

Topics: Adult; Angina Pectoris; Coronary Artery Bypass; Dose-Response Relationship, Drug; Exercise Test; Hemodynamics; Humans; Male; Middle Aged; Myocardial Ischemia; Nifedipine; Postoperative Complications; Radionuclide Ventriculography; Sodium Pertechnetate Tc 99m; Verapamil