[The use of positron emission tomography for noninvasive diagnosis of mitochondrial dysfunction and assessment of myocardial compensatory reserve in children with cardiomyopathies]. / Neinvazivnaia diagnostika mitokhondrial'noi disfunktsii i otsenka kompensatornykh vozmozhnostei miokarda u detei s kardiomiopatiiami s pomoshch'iu pozitronnoi émissionnoi tomografii.

BACKGROUND: Recent experimental and clinical studies have shown that cardiomyopathy (CMP) can be associated with disorders of oxidative metabolism in cardiomyocyte mitochondria. These disorders are connected with deficit of enzymes and complexes of electron transfer chain, and can constitute pathogenetic base of the disease. AIM. To study myocardial metabolism in children with cardiomyopathies using positron emission tomography (PET). METHODS: PET studies were carried out in 17 patients (pts.) aged 3-13 years (mean age 7,5-/+3,1) with CMP: hypertrophic (HCMP, n=4), dilated (DCMP, n=9), after radical correction of tetralogy of Fallot (TF, n=4). The dynamic study with [1-11C]-acetate was performed for evaluation of Krebs cycle activity. Rate constant (kmono) and [11C]-activity elimination half-time (T1/2) were calculated using myocardial time-activity curve. Myocardial perfusion was assessed with [13N]-ammonia, glucose metabolism - with [18F]-fluorodeoxyglucose. RESULTS: Patients with HCMP: left ventricular (LV) perfusion was normal, Krebs cycle activity - decreased; glucose utilization was increased in comparison with normal level in 2, and was normal in 2 other children. Patients with DCMP: LV perfusion was normal; Krebs cycle activity in LV was decreased in 6 and normal - in 3 pts. Overall 2 pts. with CMP had focal perfusion defects. More pronounced decrease of Krebs cycle activity in these regions compared with other LV parts implied development of ischemic injuries. Decrease of glucose utilization in these fields indicated that the injuries were irreversible. Patients with TF: 3 pts. had normal perfusion and Krebs cycle activity; 1 patient with severe hemodynamic disorders had decreased perfusion, glycolysis and Krebs cycle activity in both ventricles indicative of the presence of myocardial dystrophic changes. CONCLUSION: Despite normal perfusion children with cardiomyopathy had decreased Krebs cycle activity (mitochondrial dysfunction). Decrease in oxidative metabolism could be compensated by increased glycolysis.