[Distribution of myocardial damage in patients with hypertrophic cardiomyopathy: evaluation by exercise thallium-201 scintigraphy].

The characteristic of myocardial damage in hypertrophic cardiomyopathy (HCM) was evaluated as to whether the damage is limited to the hypertrophied wall or extends throughout the entire wall. The myocardial damage was detected by exercise thallium-201 (Tl-201) scintigraphy and was evaluated using circumferential profile analysis, calculation of initial uptake and washout rate. Eleven patients with asymmetrical hypertrophy (ASH), whose septal and posterior wall thickness ratio exceeded 1.3 on left ventriculography and biventriculography, and 13 age-matched control subjects without heart disease were studied. The mean values of initial uptake in both groups did not differ significantly, but the washout rate for the entire heart was significantly decreased only in the HCM group (p < 0.05). All of the regional washout rates (antero-septal, apical and postero-lateral) were significantly decreased in the HCM group (p < 0.05), without any difference between the hypertrophied wall and the non-thickened free wall being noted. These results demonstrated that the analysis of myocardial damage by exercise Tl-201 scintigraphy using calculation of the washout rate is a very sensitive means of detecting myocardial damage in HCM, and that such myocardial damage is not restricted to the hypertrophied wall, but rather extends to the entire wall, including the free wall which is not thickened.

[Separate evaluation of beta-methyl fatty acid uptake and perfusion in rat myocardium].

The kinetics and distribution of I-125 beta-methyl iodophenyl pentadecanoic acid (BMIPP) in rat's heart were studied for separate evaluation of perfusion and metabolism. Tl-201 and BMIPP were simultaneously injected. The experimental groups consisted of control (C), glucose (G) and sodium lactate loaded group (L). In C, myocardial uptake at 5 minutes after BMIPP injection was 3.60% ID/g and remained constant up to 60 minutes. The myocardium/lung ratio (2.44) and the myocardium/muscle ratio (4.55) of BMIPP were almost equal to those of Tl-201. But myocardium/liver ratio was low (1.31). In G, myocardial uptake of BMIPP (1.94 +/- 0.36% ID/g) and g-BMIPP/Tl (0.31 +/- 0.03) at 15 minutes after injection were significantly decreased (p less than 0.001) than those of C (3.16 +/- 0.18% ID/g and 0.48 +/- 0.05). In L. myocardial perfusion was decreased and g-BMIPP/Tl (0.73 +/- 0.14) was significantly higher (p less than 0.01) than those of C. Coefficient of variance of the density within a myocardium, and the ratio of inner to outer layer of myocardium (I/O ratio) were calculated from autoradiogram by videodensitometry. The myocardial distribution of BMIPP was more inhomogeneous, and the I/O ratio was lower than that of Tl-201, although these were not specific for metabolic interventions. In conclusion BMIPP is suitable for SPECT imaging and dual nuclide imaging by BMIPP and Tl-201 will provide informations about myocardial fatty acid metabolism and perfusion.

[Dipyridamole-loading scintigraphy in patients with subendocardial infarction using single photon emission computed tomography].

To detect myocardial lesions in patients with subendocardial (nontransmural) infarction, myocardial perfusion images of thallium-201 (T1-201), using single photon emission computed tomography, were obtained in 17 patients during and three hours after coronary vasodilatation induced by the administration of dipyridamole. Controls consisted of 28 patients with transmural infarction and 11 with angina pectoris. Dipyridamole was infused intravenously at a rate of 0.142 mg/kg per min for four min, and the washout rate of T1-201 was calculated by the segmental ROI method. The results were as follows: 1. Many patients with nontransmural infarction exhibited various T1-201 myocardial perfusion images. 2. The prevalence of redistribution among patients with nontransmural infarction was 88.2% (15 of 17), and its reverse redistribution was 64.7% (11 of 17). Every subject exhibited a number of abnormal T1-201 myocardial perfusion images. 3. In patients with nontransmural infarction the occurrence of reverse redistribution images was significantly higher (64.7%) compared to those with transmural infarction (10.7%), and the occurrence of redistribution images was significantly higher (88.2%) compared to those with angina pectoris (45.5%). 4. The abnormal perfusion images most frequently present in the areas corresponding to the sites of ST-T changes on ECG were reverse redistribution (26.7%), redistribution (17.3%), and fixed defect (6.7%) in order. 5. The phenomenon of reverse distribution images was found irrespective of stenotic coronary artery lesions on selective coronary angiography. Most areas corresponding to the sites of reverse redistribution showed ST-T changes on ECG and high washout rates of T1-201. In conclusion, these findings suggest reflections of uneven coronary blood flow and the mixed normal and scarred myocardium in patients with nontransmural infarction.