Haruhiko Adachi

Early and delayed Tc-99m-tetrofosmin myocardial SPECT in patients with left bundle branch block

To determine the utility of the myocardial tracer Tc-99m-tetrofosmin in the examination of patients with left bundle branch block (LBBB) and to investigate Tc-99m-tetrofosmin uptake and retention in the myocardium, early and delayed Tc-99m-tetrofosmin SPECT was performed in 10 patients having LBBB without coronary stenosis.Methods: After 740 MBq of Tc-99m-tetrofosmin injection in the resting state, the early and delayed SPECT imaging was done at 30 min and 180 min, respectively.Results: Decreased Tc-99m-tetrofosmin uptake in the septal segments was observed in 4 patients (40%) at 30 min and in 9 (90%) at 180 min. Reverse redistribution was seen in 9 of 10 patients. In patients with LBBB, the septal-to-lateral uptake ratio was lower in the delayed images than in the early images (0.80 ± 0.09 vs. 0.89 ± 0.09, p < 0.001). In patients with LBBB, the washout rate of Tc-99m-tetrofosmin was higher in the septal segments than in the lateral segments (28.3 ±4.3% vs. 22.8 ± 3.3%, p < 0.001).Conclusion: The SPECT data indicate that in LBBB without coronary stenosis, the uptake of Tc-99m-tetrofosmin is decreased in the septal wall, and that reverse redistribution occurs frequently. Our results contribute to the elucidation of both the cellular biokinetics of Tc-99m-tetrofosmin in the myocardium and the hemodynamics of the septum in LBBB, and indicate the possible clinical utility of Tc-99m-tetrofosmin.

Correlation of heart rate and radionuclide index of left ventricular contraction and relaxation.

Since the cardiac function indices derived from radionuclide ventriculography (RNV) are considered to depend on the heart rate, we studied the relationship between systolic or diastolic indices and heart rates in patients with normal RNV and devised a method of correcting these indices according to the heart rate.For the systolic indices, the heart rate showed significant correlation with ET (r= − 0.640), PER (r = 0.791) and TPE (r = − 0.401) but not with EF, 1/3 EF, MNSER or 1/3 MNSER. For the diastolic indices, the heart rate correlated well with FT (r = − 0.938), RFT (r = − 0.736), SFT (r = − 0.803), 1/3 FF (r = − 0.758), PFR (r = 0.759), 1/3 PFR (r= 0.742) and TPF (r= − 0.389) but not with AFT, 1/3 MNDFR or AFF.These results indicate that many systolic and diastolic indices derived from RNV are affected by the heart rate, So when cardiac function is evaluated with the use of radionuclide indices, those which are independent of the heart rate should be used, or they should be corrected for the heart rate.As a method of correction, we proposed a rotating method obtained by manipulation of the regression equation of heart rates and indices. This new method is certain and easier to use when the correcting equations are set into a computer program.

Arrhythmogenic right ventricular dysplasia. Delineation of myopathic site by intracoronary thallium-201.

Arrhythmogenic right ventricular dysplasia (ARVD) is characterized by right ventricular (RV) myopathic changes and ventricular tachycardia (VT). Myocardial scintigrams obtained by intracoronary injection of Tl- 201 chloride were useful in the diagnosis of the location and extent of dysplasia in a 23-year-old man.