PubMed · 7094283
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J M Loeb. 1982. Sinus node in SIDS.. https://pubmed.ncbi.nlm.nih.gov/7094283/
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The Smye method has been proposed to estimate the equilibrated post-dialysis BUN based on an additional intradialytic sample obtained approximately one hour into dialysis. However, the effects of access recirculation (AR) and cardiopulmonary recirculation (CPR) on the Smye computation and the corresponding details of how blood is sampled have not been studied. We examined the accuracy of two variations of the Smye technique. In one method, the intradialytic and postdialysis blood samples were obtained at full blood flow. In the other, the samples were obtained after two minutes of slow flow, to obviate the effects of both AR and CPR. Seventeen patients undergoing high efficiency dialysis and three- to four-hour treatment times were studied, in whom substantial AR was excluded based on two-minute slow flow urea rebound measurements during and just after dialysis. In this group equilibrated Kt/V (eKt/V) values computed using the Smye-derived equilibrated postBUN estimates (full flow samples, 1.22 +/- 0.058 SEM, slow flow samples, 1.23 +/- 0.064) were similar to eKt/V calculated from the 30-minute postdialysis BUN specimen (1.23 +/- 0.049, P = NS). In eight other patients with severe AR (mean 35% +/- 4.5), the accuracy of the full flow Smye estimates was poor when the degree of AR was not constant throughout the dialysis session. Accuracy of the slow flow Smye estimates of eKt/V was unaffected by the presence of severe AR. One advantage of using the full flow Smye method, however, was that a large delta Kt/V value ( < -0.40) was highly suggestive of severe AR.(ABSTRACT TRUNCATED AT 250 WORDS)
BACKGROUND: The objective of this study was to determine if dual-tracer protocol using thallium-201 (201TI) chloride for rest and technetium-99m (99mTc)-sestamibi for stress images (TI-MIBI) detects ischemia better than single-tracer protocol using 99mTc-sestamibi for both rest and stress (MIBI) myocardial perfusion images. METHODS AND RESULTS: A total of 460 patients with suspected or known coronary artery disease (CAD) were included in the study, with 230 (50%) undergoing single-tracer MIBI protocol and 230 (50%) undergoing dual-tracer TI-MIBI protocol. Patient demographics were matched, and the proportion of patients having treadmill stress or dipyridamole stress was similar between the two groups. Stress and rest single photon emission computed tomographic images were recorded in all patients and dual-tracer 201TI and 99mTc-sestamibi (TI-MIBI) perfusion images were acquired separately. The scintigraphic images were analyzed visually, and a semiquantitative method of scoring reversible ischemia was used. Patients' reversibility scores in each group were compiled (ischemia index) and compared to determine the relative ability of each protocol in identifying ischemia. CONCLUSION: The frequency of ischemia and ischemia index was found to be significantly (P < 0.05) higher in the TI-MIBI group compared with the MIBI group. For detecting myocardial ischemia or viability, the dual-tracer TI-MIBI acquisition technique appears superior to the single-tracer MIBI protocol.
UNLABELLED: The aim of this study was to assess whether nitrate administration improves the imaging capabilities of 99mTc-MIBI tomography in detecting viable myocardium in coronary artery disease (CAD). METHODS: Thirty-one patients with angiographically proven CAD and chronic LV dysfunction (ejection fraction 39% +/- 9%) underwent two 99mTc-MIBI studies on separate days: one under rest conditions and the other after nitroglycerine (0.005 mg/kg per os) administration. Within 1 wk, all patients also underwent rest-redistribution 201Tl imaging. Eight patients were also studied by echocardiography before and 5 +/- 3 mo after coronary revascularization. RESULTS: On resting 99mTc-MIBI images, 302 segments had normal uptake, 183 segments had moderately reduced uptake and 197 had severely reduced uptake. Of the segments with severely reduced uptake, 54 (27%) had increased uptake after nitroglycerine and were viable on 201Tl images. Of the 143 (73%) segments with severely reduced 99mTc-MIBI uptake and no change after nitroglycerine, 81% were nonviable on 201Tl images. In the eight patients studied before and after revascularization, 87% of segments with reversible 99mTc-MIBI defects and abnormal LV function demonstrated functional recovery after revascularization, whereas 89% of segments with irreversible 99mTc-MIBI defects did not. CONCLUSION: In patients with chronic ischemic LV dysfunction, nitrate administration improved the detection of severely hypoperfused but still viable myocardium on 99mTc-MIBI images.