Effect of regional myocardial ischemia on sympathetic nervous system as assessed by fluorine-18-metaraminol.

With the introduction of radiolabeled catecholamine analogues, the noninvasive evaluation of the cardiac sympathetic nervous system has become possible. This study evaluated the effect of regional ischemia on myocardial retention of the new norepinephrine analogue 6-[18F] fluorometaraminol (FMR) in the open chest dog model. Six dogs were injected intravenously with FMR following 30-min occlusion of the left anterior descending artery. Six sham animals served as control group. Regional myocardial blood flow as determined by microspheres decreased 87% during ischemia (p less than 0.01), but was not significantly different from control myocardium following reperfusion. Regional myocardial 18F activity as determined postmortem was significantly reduced in reperfused myocardium (-34%), which paralleled an 18% reduction of tissue norepinephrine concentration. Thus, short time periods of coronary occlusion affect neuronal function indicating the sensitivity of the sympathetic nerve terminals to ischemia. FMR provides a new tracer approach for the characterization of neuronal integrity in postischemic myocardium.

Exercise testing and thallium-201 myocardial perfusion scintigraphy in the clinical evaluation of patients with Wolff Parkinson White syndrome.

In 58 patients with Wolff Parkinson White syndrome (WPW), we performed exercise stress testing in order to investigate the incidence of normalization of the auriculo-ventricular conduction and the ST-segment changes. For a more accurate evaluation of the latter, exercise and redistribution radionuclide images with Thallium-201 were obtained in 18 cases. Forty-nine had type A and nine had type B of WPW. Forty-eight had permanent, four had alternant and six had no pre-excitation (PE) when they started the test. Mean maximal functional capacity, mean maximal heart rate and mean maximal double product were not different when compared to an age-matched control group. Of the 48 patients who began the test with PE, in 23 (48%) it disappeared while PE persisted in 25 (52%). In 16 cases the disappearance of the PE was sudden and in seven it was progressive. Pre-excitation persisted in 39.5% of patients with type A and in 88.8% with type B (p less than 0.01). ST-segment depression was observed in 76.6% of patients with PE and in 28.6% of cases without PE (p less than 0.01). ST-segment depression occurred in 44.8% of patients with type A and in 100% of cases with type B (p less than 0.05). Transient abnormal Thallium-201 scans were observed in 62.5% of patients without PE and in 20% with PE. No patients showed exertional arrhythmias. This study suggests the possibility of measuring the duration of the refractory period of the accessory pathway in those patients in which the PE disappears suddenly, at a given heart rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Método modificado para la marcación de glóbulos rojos con 99mTc / Modified method for labelling red blood cells with 99mTc

Se presenta un método simple de marcación in vivo/in vitro de glóbulos rojos con 99mTc. La sangre preestañada del paciente se incuba con el radiotrazador previo agregado de soluciones de hipoclorito de sodio y EDTA sal de sodio, según la técnica descripta por Srivastava y col. El método in vivo/in vitro fue ensayado en 18 pacientes que concurrieron para una evaluación de la fracción de eyección del ventrículo izquierdo. Se hizo un estudio comparativo con otro grupo de 11 pacientes a los cuales se aplicó el método convencional de marcación in vivo. Las imágenes obtenidas con el método in vivo/in vitro, de acuerdo con la evaluación subjetiva de 3 observadores independientes, fueron de mejor calidad y los índices de contraste presentaron menor dispersión de acuerdo al análisis estadístico (p < 0,025)

Método modificado para la marcación de glóbulos rojos con 99mTc / Modified method for labelling red blood cells with 99mTc

Se presenta un método simple de marcación in vivo/in vitro de glóbulos rojos con 99mTc. La sangre preestañada del paciente se incuba con el radiotrazador previo agregado de soluciones de hipoclorito de sodio y EDTA sal de sodio, según la técnica descripta por Srivastava y col. El método in vivo/in vitro fue ensayado en 18 pacientes que concurrieron para una evaluación de la fracción de eyección del ventrículo izquierdo. Se hizo un estudio comparativo con otro grupo de 11 pacientes a los cuales se aplicó el método convencional de marcación in vivo. Las imágenes obtenidas con el método in vivo/in vitro, de acuerdo con la evaluación subjetiva de 3 observadores independientes, fueron de mejor calidad y los índices de contraste presentaron menor dispersión de acuerdo al análisis estadístico (p < 0,025) (AU)