[Sympathetic reinnervation of the transplanted heart. Study using iodine-123 labeled meta-iodobenzylguanidine]. / Reinervación simpática del corazón trasplantado. Estudio realizado con metayodobenzilguanidina marcada con yodo-123.

INTRODUCTION AND OBJECTIVES: Metaiodobenzylguanidine (MIBG) is an analogue of norepinephrine and its cardiac uptake shows sympathetic innervation. During the heart transplantation the allograft becomes completely denervated. The present study was conducted to assess the evolution of sympathetic re-innervation after transplantation, and to related re-innervation with functional status. PATIENTS AND METHODS: We studied 31 patients from 6 months to 12 years after transplantation by 123I-MIBG studies to evaluate re-innervation and by rest/exercise radionuclide ventriculography to evaluate cardiac function. Myocardial MIBG uptake was quantified by calculating a heart-to-mediastinum ratio (HMR). An HMR > 1.8 was considered normal, moderate between 1.8 and 1.6, mild between 1.6 and 1.3, and absent < 1.3. RESULTS: HMR correlated with time after transplantation (r = 0.607; p < 0.001). HMR of patients studied after 2 years of transplantation was significantly higher (1.62 +/- 0.2 vs 1.34 +/- 0.2; p < 0.05). MIBG uptake was in the anterior region in 3 patients, in the antero-lateral region in 25, and in the antero-lateral and septal regions in 3. From a functional point of view, peak filling rate at exercise was higher in patients studied 2 years after the transplantation (2.7 +/- 0.8 edv/s vs 2.16 +/- 0.5 edv/s; p = 0.02). These patients also showed a higher increase of heart rate with exercise (p < 0.005 vs p < 0.01). CONCLUSIONS: Sympathetic re-innervation increase with time after heart transplantation, and is more frequently seen 2 years after transplantation. Sympathetic re-innervation first appears in the anterior or the antero-lateral regions. A complete re-innervation of the transplanted heart does not occur 12 years after transplantation.

[Chronic total occlusion of the left main coronary artery]. / Oclusión crónica total del tronco común de la coronaria izquierda.

Total chronic occlusion of the left main coronary artery is a rare angiographic finding in a catheterization laboratory. After reviewing the coronary angiographies performed in our laboratory between 1986 to 1995, we found a prevalence of 0.04%. These patients presented unspecific symptoms similar to other kinds of coronary artery disease. In all cases, the right coronary artery was dominant with extensive collateral circulation to the left coronary artery. Ventricular function was normal in 50% of the cases. Probably, in these unusual cases, the best therapeutic approach is surgical revascularization.